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Cited by 30Cancer-related Molecular PathwaysThyroid Cancer Diagnosis and TreatmentCancer Mechanisms and Therapy

Restoration of p53 using the novel MDM2-p53 antagonist APG115 suppresses dedifferentiated papillary thyroid cancer cells

Open access
Chen, Haibo, Luo, Dingyuan, Zhang, Lin, Lin, Xiaofeng, Luo, Qiuyun, Yi, Hanjie, Wang, Jing, Yan, Xianglei +8 more·2017·Oncotarget
DOI 10.18632/oncotarget.17398PMC PMC5522123
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Abstract

// Haibo Chen 1, * , Dingyuan Luo 2, * , Lin Zhang 3, 4, * , Xiaofeng Lin 1 , Qiuyun Luo 3 , Hanjie Yi 3 , Jing Wang 5 , Xianglei Yan 3 , Baoxia Li 3 , Yuelei Chen 6 , Xingguang Liu 1 , Hong Zhang 1 , Sheng Liu 1 , Miaozhen Qiu 7 , Dajun Yang 3, 8 and Ningyi Jiang 1 1 Department of Nuclear Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China 2 Department of Vascular and Thyroid Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China 3 Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China 4 Department of Clinical Laboratory, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China 5 Department of Pharmacy, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, China 6 The State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China 7 Department of Medical Oncology, Sun Yat-Sen University Cancer Center, Guangzhou 510120, China 8 Suzhou Ascentage Pharma Inc., Jiangsu 215123, China * These authors have contributed equally to this work Correspondence to: Dajun Yang, email: yangdj@sysucc.org.cn Ningyi Jiang, email: ningyij0@163.com Keywords: dedifferentiated thyroid cancer, radioiodine, anti-tumor, MDM2-p53 interaction, apoptosis Received: February 10, 2017 Accepted: April 06, 2017 Published: April 24, 2017 ABSTRACT Dedifferentiated papillary thyroid cancer (DePTC) is characterized by aggressive growth, recurrence, distant metastasis, and resistance to radioactive iodine (RAI) therapy. DePTC is also accompanied by poor prognosis and high early-mortality. Nevertheless, most DePTC cells show intact p53 downstream functionality. In cells with wild-type p53, the murine double minute2 (MDM2) protein interacts with p53 and abrogates its activity. Inhibition of the MDM2-p53 interaction restores p53 activity and leads to cell cycle arrest and apoptosis. Restoring p53 function by inhibiting its interaction with p53 suppressors such as MDM2 is thus a promising therapeutic strategy for the treatment of DePTC. The novel MDM2-p53 interaction antagonist APG115 is an analogue of SAR405838, and is being tested in a phase I clinical trial. In this study, we evaluated the efficacy of APG115 as a single-agent to treat DePTC. APG115 diminished the viability of p53 wild-type DePTC cells and induced cell cycle arrest and apoptosis. In a human xenograft mouse model, APG115 elicited robust tumor regression and cell apoptosis. These data demonstrate that further research is warranted to determine whether APG115 can be used to effectively treat DePTC patients.

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Written from the paper’s full text.

TL;DR

APG115, a novel MDM2-p53 interaction antagonist, restored p53 signaling and suppressed p53 wild-type dedifferentiated papillary thyroid cancer (DePTC) cells in vitro and in TPC-1 xenografts. Its effects were p53-dependent and more potent than the analogue SAR405838, supporting further preclinical/clinical evaluation in DePTC.

Key findings

  • APG115 inhibited proliferation of wild-type p53 DePTC cell lines with nanomolar IC50 values: 133.4 ± 28.3 nM for TPC-1 and 94.8 ± 38.0 nM for KTC-1, versus 77.8 ± 22.5 μM in p53-mutated B-CPAP cells.
  • Stable p53 knockdown in TPC-1 shifted the IC50 from 158.2 ± 30.3 nM (sh-NC) to 445.6 ± 49.2 μM (sh-p53), and abrogated APG115-induced cell-cycle arrest and apoptosis.
  • APG115 induced G2/M arrest and reduced S-phase cells in wild-type p53 lines: TPC-1 S-phase fell from 35.4% to 2% and G2/M rose from 16.7% to 63.2%; KTC-1 S-phase fell from 31.7% to 0.6%.
  • In TPC-1 xenografts, daily oral APG115 for 15 days suppressed tumor growth by 35.4% at 25 mg/kg and 58.2% at 50 mg/kg; 100 mg/kg caused regression, with average tumor volume at day 46 still below the primary volume.

Methods

  • In vitro: DePTC cell lines TPC-1 and KTC-1 (wild-type p53) and B-CPAP (mutant p53) were treated with APG115 or SAR405838; assays included MTS viability, xCELLigence RTCA, flow cytometry for cell cycle/apoptosis, RT-qPCR, western blot, and stable shRNA p53 knockdown.
  • In vivo: female BALB/c nude mice bearing subcutaneous TPC-1 xenografts received vehicle or APG115 orally; efficacy used 25, 50, and 100 mg/kg daily for 15 days, with tumor volume/weight and mouse weight recorded. Pharmacodynamic, immunohistochemical Ki-67, TUNEL, immunofluorescence, and caspase-3/7 bioluminescence assays were also performed.
  • Statistics: data reported as mean ± SD; significance assessed by two-tailed paired or unpaired Student’s t test and ANOVA with Kruskal-Wallis test.

Limitations

  • Stated limitations: Not stated in the paper.
  • Evident from the text: the study is preclinical only, using DePTC cell lines and a TPC-1 xenograft model, with no patient-derived or clinical efficacy/safety data.
  • Evident from the text: APG115 activity required wild-type p53, so the approach may not apply to p53-mutated DePTC; in vivo efficacy was shown primarily in one xenograft model, and long-term toxicity was not comprehensively assessed beyond body-weight monitoring.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.18632/oncotarget.17398

Cites

53 of 53 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 42 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    APG115 led to only a 1.5-fold increase in apoptosis at 10 μM in B-CPAP.

    “However, APG115 led to only 1.5-fold increase in cell apoptosis at 10 μM in the B-CPAP cell line (Figure 2D).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: TPC-1 and KTC-1 have wild-type functional p53, and B-CPAP has mutated p53.
  • Findingown data

    APG115 induced apoptosis in p53 wild-type DePTC cells.

    “APG115 diminished the viability of p53 wild-type DePTC cells and induced cell cycle arrest and apoptosis.”
    Quote in the paperSubstantial claim
  • Findingown data

    APG115 was approximately three times more potent than SAR405838 in decreasing viability of TPC-1 and KTC-1 cells (P < 0.01).

    “In addition, APG115 was approximately three times more potent than SAR405838 in decreasing the viability of TCP-1 cells (P < 0.01) and KTC-1 cells (P < 0.01, Figure 1F).”
    Quote in the paperNot a substantial claim
  • Findingown data

    A similar increase of MDM2, p21, and PUMA was detected in KTC-1 cells in response to APG115.

    “A similar increase of the same genes was detected in response to APG115 treatment in KTC-1 cells.”
    Quote in the paperNot a substantial claim
  • Findingown data

    There was no upregulation of MDM2, p21, and PUMA in B-CPAP expressing mutant p53.

    “Nevertheless, there was no upregulation in cell line B-CPAP expressing mutant p53 (Figure 3A).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: TPC-1 and KTC-1 have wild-type functional p53, and B-CPAP has mutated p53.
  • May combine two claims. 37
  • Classified as probably not a substantial claim. 20

  • May combine two claims.

    Findingown data

    This effect was detected in two DePTC cell lines with wild-type p53, whereas there was no increase in p53 and its transcriptional targets in B-CPAP cells.

    “This effect was detected in two DePTC cell lines with wild type p53, whereas there was no increase in p53 and its transcriptional targets in B-CPAP cells (Figure 3B).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: TPC-1 and KTC-1 have wild-type functional p53, and B-CPAP has mutated p53.

  • May combine two claims.

    Findingown data

    Both APG115 and SAR405838 restored p53 activity in a dose-dependent manner.

    “Both of the two antagonist restored p53 activity in a dose-dependent manner.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The IC50 of SAR405838 was 576.3 ± 17.5 nM for TPC-1 and 276.6 ± 42.3 nM for KTC-1.

    “The IC50 values of SAR405838 were 576.3 ± 17.5 nM and 276.6 ± 42.3 nM (mean ± SD) for TPC-1cells and KTC-1 cells, respectively (Supplementary Table 1).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    APG115 induced a 5-fold increase in MDM2 (P=0.0165), 7-fold increase in p21 (P=0.0054), and 2-fold increase in PUMA (P=0.0342) in TPC-1 cells.

    “APG115 induced a 5-fold increase in MDM2 expression (P =0.0165), a 7-fold increase in p21 expression (P =0.0054), and a 2-fold increase in PUMA expression (P =0.0342) in TPC-1 cells.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In TPC-1, APG115 reduced S-phase population from 35.4% to 2% and increased G2/M from 16.7% to 63.2%.

    “In response to increasing concentrations of APG115 (0-10 μM), the TPC-1 cell population in S-phase reduced from 35.4% to 2%, whereas accumulation of cells at G2/M phases increased from 16.7% to 63.2% (Figure 2A).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The IC50 of APG115 in TPC-1 sh-NC was 158.2 ± 30.3 nM, whereas in TPC-1 sh-p53 was 445.6 ± 49.2 μM.

    “The IC50 value for stably transfected negative control cell line TPC-1 sh-NC was 158.2 ± 30.3 nM (mean ± SD), whereas the IC50 value for stable p53 knockdown cell line TPC-1 sh-p53 was 445.6 ± 49.2 μM (mean ± SD) (Supplementary Table 1).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Immunofluorescence showed p53 and MDM2 levels increased 4 h after treatment, peaked at 8 h, and returned to basal levels at 24 h in response to APG115 100 mg/kg.

    “We also found by immunofluorescence that p53 and MDM2 levels increased 4 h after treatment, peaked at 8 h, and returned to basal levels at 24 h in response to APG115 treatment (100 mg/kg)(Figure 5B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    A large increase in TUNEL positive cells was seen in tumors after 100 mg/kg APG115, while only a mild increase was seen after 50 mg/kg, and the number after 25 mg/kg was similar to vehicle controls.

    “A large increase in TUNEL positive cells was seen in tumors after administration of 100 mg/kg APG115 while only a mild increase was seen after administration of 50 mg/kg. On the other hand, the number of TUNEL positive cells after administration of 25 mg/kg APG115 was similar to that of vehicle-treated controls (Figure 6A, right).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    At 100 mg/kg, a majority of TPC-1 xenograft tumors regressed and average tumor volume was below the primary average volume.

    “At the high dose of 100 mg/kg, a majority of TPC-1 xenograft tumors regressed and the average tumor volume was below the primary average volume.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Treatment of TPC-1 and KTC-1 with APG115 for 24 h led to concentration-dependent cell cycle arrest in G2/M phases and a decrease in S-phase.

    “Treatment of exponentially proliferating DePTC p53 wide-type cell lines (TPC-1, KTC-1) with APG115 for 24 h led to a concentration-dependent cell cycle arrest in G2/M phases and a decrease in the number of cells in S-phase.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: TPC-1 and KTC-1 have wild-type functional p53, and B-CPAP has mutated p53.

  • May combine two claims.

    Findingown data

    Efficient stable knockdown of p53 in TPC-1 effectively abrogated expression of p53, p21, MDM2, and PUMA in response to APG115, whereas TPC-1 sh-NC did not cause concentration-dependent upregulation of those proteins.

    “Furthermore, efficient stable knockdown of p53 in TPC-1 (TPC-1 sh-p53) cells effectively abrogated expression of p53, p21, MDM2, and PUMA (Figure 3C) in response to APG115 treatment, whereas stably transfected negative control shRNAi TPC-1 (TPC-1 sh-NC) cells did not cause concentration-dependent upregulation of those proteins.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Apoptosis was delayed, being minimal at less than 24 h, but prominent at the highest dose of APG115 after 48 h post treatment.

    “On the other hand, apoptosis was delayed, being minimal at less than 24 h, but prominent at the highest dose of APG115 after 48 h post treatment.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    APG115 inhibited cell proliferation in wild-type p53 DePTC cell lines TPC-1 and KTC-1 in a concentration-dependent manner over 72 hours, but to a much lesser extent in p53-mutated B-CPAP.

    “We found that APG115 inhibited cell proliferation in wild-type p53 DePTC cell lines (TPC-1 and KTC-1) in a concentration-dependent manner over a 72-hour period, but to a much lesser extent in the p53-mutated DePTC cell line (B-CPAP) (P < 0.0001).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: TPC-1 and KTC-1 have wild-type functional p53, and B-CPAP has mutated p53.

  • May combine two claims.

    Findingown data

    Increasing concentrations of APG115 resulted in concentration-dependent accumulation of p53 protein with subsequent restoration of transcriptional targets involved in cell-cycle arrest and apoptotic stress responses.

    “Increasing concentrations of APG115 resulted in a concentration-dependent accumulation of p53 protein with subsequent restoration of transcriptional targets involved in cell-cycle arrest and apoptotic stress responses.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The protein levels of p53, MDM2, and p21 were highest at 8 h after treatment and returned to primary levels at 24 h.

    “The protein levels of p53 and its interactional protein MDM2 and p21 were highest at 8 h after treatment and returned to primary levels at 24 h (Figure 5A).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The IC50 of APG115 in TPC-1 was 133.4 ± 28.3 nM, in KTC-1 was 94.8 ± 38.0 nM, and in B-CPAP was 77.8 ± 22.5 μM.

    “The DePTC cell lines with wild-type p53 had nanomolar IC50 values of 133.4 ± 28.3 nM (mean±standard deviation (SD)) for TPC-1, and 94.8 ± 38.0 nM (mean ± SD) for KTC-1). On the other hand, the p53-mutated DePTC cell line had an IC50 value of 77.8 ± 22.5 μM (mean ± SD) (Figure 1B) (Supplementary Table 1).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: TPC-1 and KTC-1 have wild-type functional p53, and B-CPAP has mutated p53.

  • May combine two claims.

    Findingown data

    The tumor regression at 100 mg/kg was long-lasting; at day 46, 13 days after last treatment, average tumor volume of all eight mice remained below primary volume.

    “The tumor regression obtained in response to APG115 treatment at 100 mg/kg was long-lasting; at day 46, 13 days after the last treatment, the average tumor volume of all eight mice remained below the primary volume.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    APG115 elicited both cell-cycle arrest and apoptosis in a concentration-dependent manner, with an early onset for cell-cycle blockage and a late onset for apoptosis in DePTC cells.

    “Our data here showed that APG115 elicited both cell-cycle arrest and apoptosis in a concentration-dependent manner but manifested different kinetics for these two cellular processes, with an early onset for cell-cycle blockage and a late onset for apoptosis.”
    • Also stated in: § DISCUSSION · plain
      “We also showed that cell-cycle blockage preceded apoptosis induction in vitro.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    APG115 inhibited proliferation and induced apoptosis in a dose-dependent manner in TPC-1 xenograft tumor tissues.

    “thereby inhibiting proliferation and inducing apoptosis in a dose-dependent manner”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    APG115 restored p53 and upregulated p53 transcriptional target genes in DePTC cells with wild-type p53.

    “It also restored p53 and upregulated p53 transcriptional target genes in DePTC cells with wild-type p53.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: TPC-1 and KTC-1 have wild-type functional p53, and B-CPAP has mutated p53.

  • May combine two claims.

    Findingown data

    APG115 achieved dose-dependent p53 restoration and upregulation of p53 downstream transcriptional targets in TPC-1 xenograft tumor tissues.

    “achieving dose-dependent p53 restoration and upregulation of p53 downstream transcriptional targets in TPC-1 xenograft tumor tissues”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    APG115 is an analogue of SAR405838 and is being tested in a phase I clinical trial.

    “The novel MDM2-p53 interaction antagonist APG115 is an analogue of SAR405838, and is being tested in a phase I clinical trial.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites NCT02935907

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    APG115 can effectively arrest the cell-cycle and tumor cell proliferation.

    “suggesting that APG115 can effectively arrest the cell-cycle and tumor cell proliferation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Cellular dedifferentiation in thyroid carcinoma is accompanied by more aggressive growth, recurrence, distant metastasis, and resistance to RAI.

    “Cellular dedifferentiation generally occurs in cases accompanied by more aggressive growth, recurrence, distant metastasis, and resistance to RAI [1, 8–10].”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [1] Antonelli, 2015, New therapies for dedifferentiated papillary thyroid cancer, Int J Mol Sci source

      Not checked in the free run.

    • cites [8] Patel, 2013, Genetic mutations, molecular markers and future directions in research, Oral Oncol source

      Not checked in the free run.

    • cites [9] Fontanini, 2011, Novel pyrazolopyrimidine derivatives as tyrosine kinase inhibitors with antitumoral activity in vitro and in vivo in papillary dedifferentiated thyroid cancer, J Clin Endocrinol Metab source

      Not checked in the free run.

    • cites [10] Tuttle, 2009, Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer, Thyroid source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Inhibition of the MDM2-p53 interaction restores p53 activity and leads to cell cycle arrest and apoptosis.

    “Inhibition of the MDM2-p53 interaction restores p53 activity and leads to cell cycle arrest and apoptosis.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [19] Shangary, 2014, SAR405838: an optimized inhibitor of MDM2-p53 interaction that induces complete and durable tumor regression, Cancer Res source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisenone given

    In cells with wild-type p53, MDM2 interacts with p53 and abrogates its activity.

    “In cells with wild-type p53, the murine double minute2 (MDM2) protein interacts with p53 and abrogates its activity.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Approximately 5-15% of PTC cases are DePTC, associated with poor prognosis and high early-mortality.

    “Nevertheless, approximately 5-15% of the cases are dedifferentiated papillary thyroid cancer (DePTC), which is associated with poor prognosis and high early-mortality [7–9].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [7] Ji, 2015, Sulforaphane inhibits thyroid cancer cell growth and invasiveness through the reactive oxygen species-dependent pathway, Oncotarget source

      Not checked in the free run.

    • cites [8] Patel, 2013, Genetic mutations, molecular markers and future directions in research, Oral Oncol source

      Not checked in the free run.

    • cites [9] Fontanini, 2011, Novel pyrazolopyrimidine derivatives as tyrosine kinase inhibitors with antitumoral activity in vitro and in vivo in papillary dedifferentiated thyroid cancer, J Clin Endocrinol Metab source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    DePTC accounts for approximately 5-10% of patients with PTC, leads to resistance to traditional therapeutic strategies and worsens prognosis.

    “DePTC, which accounts for approximately 5-10% of patients with PTC, leads to resistance to traditional therapeutic strategies and worsens prognosis [9, 10, 29].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [9] Fontanini, 2011, Novel pyrazolopyrimidine derivatives as tyrosine kinase inhibitors with antitumoral activity in vitro and in vivo in papillary dedifferentiated thyroid cancer, J Clin Endocrinol Metab source

      Not checked in the free run.

    • cites [10] Tuttle, 2009, Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer, Thyroid source

      Not checked in the free run.

    • cites [29] Schlumberger, 2007, New therapeutic approaches for metastatic thyroid carcinoma, Lancet Oncol source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Spiro-oxindoles induce an increase in transcription and protein levels of p53-target genes.

    “They induce an increase in transcription and protein levels of p53-target genes [41].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] Wang, 2009, Potent and orally active small-molecule inhibitors of the MDM2-p53 interaction, J Med Chem source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Dedifferentiation in thyroid carcinoma is characterized by loss of thyroid specific markers and gain of proliferative capacity.

    “Furthermore, dedifferentiation in thyroid carcinoma is characterized by a loss of thyroid specific markers and a subsequent gain of proliferative capacity [36, 37].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [36] Maenhaut, 2007, Human thyroid tumor cell lines derived from different tumor types present a common dedifferentiated phenotype, Cancer Res source

      Not checked in the free run.

    • cites [37] Sonoo, 2000, All-trans-retinoic acid modulates expression levels of thyroglobulin and cytokines in a new human poorly differentiated papillary thyroid carcinoma cell line, KTC-1, J Clin Endocrinol Metab

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Analysis of crystal structure of MDM2-p53 complex showed interaction primarily mediated by three hydrophobic residues Phe19, Trp23, Leu26 of p53 peptide and a small deep hydrophobic cleft in MDM2.

    “Analysis of the crystal structure of the MDM2-p53 complex showed that the interaction between MDM2 and its transcriptional factor p53 was primarily mediated by three hydrophobic residues, namely Phe19, Trp23, and Leu26 of a p53 peptide and a small deep hydrophobic cleft in MDM2 [38].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] Arya, 2014, Small molecule modulators of protein-protein interactions: selected case studies, Chem Rev source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Each sample and gene was conducted in triplicate.

    “Each sample and gene was conducted in triplicate.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    APG115 was shown to have very high affinity to MDM2 (Ki<1 nM) and potent cellular activity.

    “Meanwhile, it was shown a very high affinity to MDM2 (Ki<1 nM), and potent cellular activity [26].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [26] Wen, 2017, Discovery of 4-((3′R,4′S,5′R)-6″-Chloro-4′-(3- chloro-2-fluorophenyl)-1′-ethyl-2″-oxodispiro[cyclohexane-1,2′-pyrrolidine-3′,3″-indoline]-5′-carboxamido)bicyclo[2.2.2] octane-1-carboxylic Acid (AA-115/APG-115): A Potent and Orally Active Murine Double Minute 2 (MDM2) Inhibitor in Clinical Development, J Med Chem source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisenone given

    APG115 is derived from SAR405838 and is a new spiro-oxindole with two identical substituents at carbon-2 of the pyrrolidine core, with more chemical stability.

    “The novel MDM2-p53 antagonist, APG115, is derived from SAR405838. It is a new spiro-oxindole with two identical substituents at the carbon-2 of the pyrrolidine core, with more chemically stability.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All cell lines were passaged less than one month prior to banking and experimentation.

    “All cell lines were passaged less than one month prior to banking and experimentation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    PTC patients with RET/PTC rearrangements or BRAFV600E mutation exhibit cell dedifferentiation.

    “PTC patients with RET/PTC rearrangements [30–32] or the BRAFV600E mutation [33, 34] exhibit cell dedifferentiation.”
    Quote in the paperSubstantial claim0 of 5 sources checked
    • cites [30] Mesa, 2007, Clinical significance of RET/PTC and p53 protein expression in sporadic papillary thyroid carcinoma, Histopathology source

      Not checked in the free run.

    • cites [31] Vitale, 2012, Rethinking the role of oncogenes in papillary thyroid cancer initiation, Front Endocrinol (Lausanne) source

      Not checked in the free run.

    • cites [32] Fallahi, 2010, New targeted molecular therapies for dedifferentiated thyroid cancer, J Oncol

      Not checked in the free run.

    • cites [33] Santisteban, 2009, The BRAFV600E oncogene induces transforming growth factor beta secretion leading to sodium iodide symporter repression and increased malignancy in thyroid cancer, Cancer Res source

      Not checked in the free run.

    • cites [34] Fagin, 2005, Targeted expression of BRAFV600E in thyroid cells of transgenic mice results in papillary thyroid cancers that undergo dedifferentiation, Cancer Res source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    TPC-1 cells were stably transfected with shRNA-p53 or scrambled sequence control shRNA.

    “The DePTC cells (TPC-1) were stably transfected with lentiviral vectors expressing shRNA-p53 corresponding to p53 nucleotides 611-629 [52] or scrambled sequence control shRNA (GenePharma, 20 Suzhou, China) for 3 days and then selected with 1.0 μg/ml puromycin (sigma, Shanghai, China) for 2 weeks.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [52] Bradford, 2006, A novel BH3 mimetic reveals a mitogen-activated protein kinase-dependent mechanism of melanoma cell death controlled by p53 and reactive oxygen species, Cancer Res source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Restoration of p53 blocks cell-cycle progression and induces apoptosis in the presence of MDM2-p53 interaction antagonists.

    “Restoration of p53 is known to block cell-cycle progression and induces apoptosis in the presence of MDM2-p53 interaction antagonists [43–45].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [43] Vassilev, 2006, Small-molecule MDM2 antagonists reveal aberrant p53 signaling in cancer: implications for therapy, Proc Natl Acad Sci U S A source

      Not checked in the free run.

    • cites [44] Podlaski, 2013, MDM2 small-molecule antagonist RG7112 activates p53 signaling and regresses human tumors in preclinical cancer models, Cancer Res source

      Not checked in the free run.

    • cites [45] Vassilev, 2007, MDM2 inhibitors for cancer therapy, Trends Mol Med source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Each data point was determined by triplicate assays.

    “Each data point was determined by triplicate assays.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Thyroid carcinomas are more prevalent among women.

    “Thyroid carcinomas are more prevalent among women.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [4] He, 2016, Cancer statistics in China, 2015, CA Cancer J Clin source

      Not checked in the free run.

    • cites [5] Jemal, 2016, Cancer statistics, 2016, CA Cancer J Clin source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    p53 induces cell cycle arrest to protect cells from propagation of damaged DNA before it is repaired, whereas apoptosis eliminates cells with unrepairable damage.

    “Presumably, p53 induces cell cycle arrest to protect cells from propagation of damaged DNA before it is repaired, whereas apoptosis eliminates cells with unrepairable damage [44].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [44] Podlaski, 2013, MDM2 small-molecule antagonist RG7112 activates p53 signaling and regresses human tumors in preclinical cancer models, Cancer Res source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    APG115 is currently investigated in a phase I trial in patients with advanced solid tumor or lymphoma (NCT02935907).

    “This antagonist is currently investigated in a phase I trial in patients with advanced solid tumor or lymphoma (NCT02935907).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites NCT02935907

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    GAPDH or Actin was used as a loading control in Western blot analysis.

    “GAPDH or Actin (Beyotime, Shanghai, China) was used as a loading control.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Both KTC-1 and TPC-1 harbor mutations (RET/PTC1 and BRAFV600E, respectively) that upregulate MAPK/ERK signaling associated with promoting tumor migration and metastases.

    “Both the cell lines KTC-1 and TPC-1 harbor mutations (RET/PTC1 and BRAFV600E, respectively) that upregulate MAPK/ERK signaling transductions associated with promoting tumor migration and metastases [35].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [35] Henderson, 2015, LGR5 is associated with tumor aggressiveness in papillary thyroid cancer, Oncotarget source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    SAR405838 has demonstrated potent single-agent efficacy in various cell lines and xenograft tumor models and is being investigated in a Phase I clinical trial.

    “SAR405838 has demonstrated potent single-agent efficacy in various cell lines and xenograft tumor models and is being investigated in a Phase I clinical trial [42].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [42] Nor, 2016, Therapeutic inhibition of the MDM2-p53 interaction prevents recurrence of adenoid cystic carcinomas, Clin Cancer Res source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Dedifferentiated thyroid cell lines usually overexpress genes involved in general metabolism, cell cycle, and proliferation.

    “Dedifferentiated thyroid cell lines usually overexpress genes involved in general metabolism, cell cycle, and proliferation [36].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [36] Maenhaut, 2007, Human thyroid tumor cell lines derived from different tumor types present a common dedifferentiated phenotype, Cancer Res source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Spiro-oxindoles invented by Wang's laboratory constitute a new class of MDM2-p53 interaction antagonists developed using structure-based de novo design.

    “Spiro-oxindoles invented by Wang's laboratory constitute is a new class of MDM2-p53 interaction antagonists that were developed using a structure-based de novo design strategy [39].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] Wang, 2005, Structure-based design of potent non-peptide MDM2 inhibitors, J Am Chem Soc source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    RET/PTC rearrangements are found in 30-40% of DePTC cases, whereas BRAF mutations are up to 70%.

    “RET/PTC rearrangements are found in 30-40% of cases, whereas a higher prevalence of BRAF mutations (up to 70%) has been observed in DePTC [9].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [9] Fontanini, 2011, Novel pyrazolopyrimidine derivatives as tyrosine kinase inhibitors with antitumoral activity in vitro and in vivo in papillary dedifferentiated thyroid cancer, J Clin Endocrinol Metab source

      Not checked in the free run.

48 of 48

  • The paper relies on this without support.

    MDM2-p53 interaction antagonist has not yet been investigated in thyroid carcinomas.

    “To our knowledge, MDM2-p53 interaction antagonist has not yet been investigated in thyroid carcinomas.”

  • The paper relies on this without support.

    TPC-1 and KTC-1 have wild-type functional p53, and B-CPAP has mutated p53.

    “cell lines KTC-1 and TPC-1 retaining intact p53 functions are ideal models”

  • The paper relies on this without support.

    Efficacy in TPC-1 xenograft mice predicts efficacy in human DePTC patients.

    “In a human xenograft mouse model, APG115 elicited robust tumor regression and cell apoptosis.”

  • The paper relies on this without support.

    Preclinical in vitro and mouse xenograft results with APG115 are predictive of clinical efficacy in DePTC patients.

    “The robust tumor regression we observed in xenograft models of DePTC with wild-type p53 after APG115 treatment suggests that this MDM2-p53 interaction antagonist may be used as a therapeutic alternative to treat DePTC patients.”

  • The paper relies on this without support.

    The DePTC cell lines used (KTC-1, TPC-1, B-CPAP) are representative models of human dedifferentiated papillary thyroid cancer.

    “Cell lines KTC-1 and TPC-1 (harboring BRAFV600E mutation and RET/PTC1 rearrangement, respectively) have wild type p53, whereas B-CPAP (harboring the BRAFV600E mutation) is a p53 mutant [46, 47].”

  • The paper relies on this without support.

    Maintenance of mouse body weight is a sufficient indicator that tumor regression is not accompanied by notable systemic toxicities.

    “As demonstrated by the maintenance of mice weight throughout the experimental period, the neoplasm regression was not accompanied by notable signs of systemic toxicities.”

  • The paper relies on this without support.

    A 2-week observation period after therapy withdrawal is sufficient to detect neoplasm regrowth.

    “Noticeably, no neoplasm regrowth was observed when the therapy was withdrawn and xenograft tumors were observed for another 2 weeks.”

  • The paper relies on this without support.

    APG115's oral pharmacokinetics in athymic nude mice are representative of its pharmacokinetics in humans.

    “APG115 demonstrated promising oral pharmacokinetics in athymic nude mice, achieving dose-dependent p53 restoration and upregulation of p53 downstream transcriptional targets in TPC-1 xenograft tumor tissues, thereby inhibiting proliferation and inducing apoptosis in a dose-dependent manner.”
8 of 8

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • In vivo experiments have demonstrated that when combined with radiotherapy, APG-115 can enhance the in vivo radioantitumor effect of gastric adenocarcinoma.

    “In vivo experiments have demonstrated that when combined with radiotherapy, APG-115 can enhance the in vivo radioantitumor effect of gastric adenocarcinoma.406”

    From Recent advances in targeting the “undruggable” proteins: from drug discovery to clinical trials (2023) · cites this paper as [406]

  • APG-115 has been found to activate p53, enhance the radiosensitivity of AGS and MKN45 cells, and induce concentration-dependent G2/M phase arrest and S phase reduction in wild-type p53 cell lines (TPC-1, KTC-1).

    “It has also been found to activate p53, enhance the radiosensitivity of AGS and MKN45 cells, and induce concentration-dependent G2/M phase arrest and S phase reduction in wild-type p53 cell lines (TPC-1, KTC-1).”

    From Recent advances in targeting the “undruggable” proteins: from drug discovery to clinical trials (2023) · cites this paper as [406]

  • In vitro studies have shown that APG-115 has an impact on disease progression by inducing AGS and MKN45 cells with wild-type p53 to be blocked in the G0/G1 phase.

    “In vitro studies have shown that APG-115 has an impact on disease progression by inducing AGS and MKN45 cells with wild-type p53 to be blocked in the G0/G1 phase.”

    From Recent advances in targeting the “undruggable” proteins: from drug discovery to clinical trials (2023) · cites this paper as [406]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Reported seven-fold difference between cell-cycle and apoptosis doses is too small

    Major

    The apoptosis EC50 is greater than 3 μM and the S-phase EC50 is 0.08 μM, so the apoptosis dose is more than 37.5 times higher, not approximately seven times higher.

    Reported 7 · recomputed 37.5

  • KTC-1 and TPC-1 mutations are assigned to opposite cell lines

    Minor

    The discussion assigns RET/PTC1 to KTC-1 and BRAFV600E to TPC-1, while the methods assign BRAFV600E to KTC-1 and RET/PTC1 to TPC-1.

  • Negative-control cells are described as unaffected by APG115

    Minor

    The results say cell-cycle arrest and apoptosis were unaffected in the negative-control shRNA cells, yet describe p53 knockdown as abrogating those APG115-induced effects. If the negative controls were unaffected too, that comparison does not show an effect of knocking down p53.

3 of 3

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Authors
Chen, H., Luo, D., Zhang, L., Lin, X., Luo, Q., Yi, H., Wang, J., Yan, X., Li, B., Chen, Y., Liu, X., Zhang, H., Liu, S., Qiu, M., Yang, D., & Jiang, N.
Affiliations
  • Sun Yat-sen University (CN)
  • Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China
  • The First Affiliated Hospital, Sun Yat-sen University (CN)
  • Chinese Academy of Sciences (CN)
  • Department of Medical Oncology, Sun Yat-Sen University Cancer Center, Guangzhou 510120, China
Corresponding author
  • Chen, Haibo
  • Luo, Dingyuan
  • Zhang, Lin
ORCID
Venue
Oncotarget
Publisher
Impact Journals, LLC
Published
2017-04-24
Volume
8
Issue
26
Pages
43008-43022
ISSN
1949-2553 (ISSN-L)
DOI
10.18632/oncotarget.17398
PMC
PMC5522123
OpenAlex
W2608088676
Semantic Scholar
12c85568a5b2041de56f51f6c9e362f84c1bef3b
Cited by
29
References
53
Citations by year
2026: 2 · 2025: 5 · 2024: 5 · 2023: 1 · 2022: 6 · 2021: 3 · 2020: 3 · 2019: 2 · 2018: 2
FWCI
0.84
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Oncotarget (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • National Natural Science Foundation of China (81071187, 81602066)
  • Sun Yat-sen University
  • Fundamental Research Funds for the Central Universities (16ykpy25)
  • Science and Technology Planning Project of Guangdong Province
  • Sun Yat-sen University Cancer Center
Topics
  • Health Sciences › Medicine › Oncology › Cancer-related Molecular Pathways
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Cancer Diagnosis and Treatment
  • Health Sciences › Medicine › Pathology and Forensic Medicine › Cancer Mechanisms and Therapy
Keywords
MDM2-p53 antagonist, p53 restoration, dedifferentiation, radioiodine resistance, apoptosis, cell cycle arrest, tumor growth inhibition, xenograft tumor model, metastasis, metastatic lung, liver metastasis, metastatic bone
MeSH terms
Animals, Carcinoma, Papillary, Cell Survival, Disease Models, Animal, Dose-Response Relationship, Drug, Female, Humans, Indoles, Mutation, Spiro Compounds, Thyroid Neoplasms, Gene Expression, Tumor Suppressor Protein p53, Apoptosis, Xenograft Model Antitumor Assays, Cell Line, Tumor, Cell Proliferation, Mice, Proto-Oncogene Proteins c-mdm2, Protein Stability, Cell Cycle Checkpoints, Neoplasm Grading

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-06.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-06.

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