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Cited by 10MicroRNA in disease regulationProstate Cancer Treatment and ResearchCancer-related molecular mechanisms research

miR-33b-3p Acts as a Tumor Suppressor by Targeting DOCK4 in Prostate Cancer

Open access
Mei, Yu, Li, Kai, Zhang, Zhicheng, Li, Mengmeng, Yang, Hong, Wang, Hui, Huang, Xuemei, Li, Xinyuan +2 more·2021·Frontiers in Oncology
DOI 10.3389/fonc.2021.740452PMC PMC8595470
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Abstract

Despite that androgen-deprivation therapy results in long-lasting responses, the disease inevitably progresses to metastatic castration-resistant prostate cancer. In this study, we identified miR-33b-3p as a tumor suppressor in prostate cancer. miR-33b-3p was significantly reduced in prostate cancer tissues, and the low expression of miR-33b-3p was correlated with poor overall survival of prostate cancer patients. Overexpression of miR-33b-3p inhibited both migration and invasion of highly metastatic prostate cancer cells whereas inhibition of miR-33b-3p promoted those processes in lowly metastatic cells. The in vivo results demonstrate that miR-33b-3p suppresses metastasis of tail vein inoculated prostate cancer cells to lung and lymph nodes in mice. DOCK4 was validated as the direct target of miR-33b-3p. miR-33b-3p decreased the expression of DOCK4 and restoration of DOCK4 could rescue miR-33b-3p inhibition on cell migration and invasion. Moreover, downregulation of miR-33b-3p was induced by bortezomib, the clinically used proteasome inhibitor, and overexpression of miR-33b-3p enhanced the insufficient inhibition of bortezomib on migration and invasion as well as metastasis of prostate cancer cells. In summary, our findings demonstrate that miR-33b-3p suppresses metastasis by targeting DOCK4 in prostate cancer. Our results suggest that enhancing miR-33b-3p expression may provide a promising therapeutic strategy for overcoming that proteasome inhibitor’s poor efficacy against metastatic prostate cancer.

AI snapshot

Written from the paper’s full text.

TL;DR

miR-33b-3p is downregulated in prostate cancer and acts as a metastasis suppressor by directly targeting DOCK4. Overexpressing miR-33b-3p inhibits migration, invasion, and in vivo metastasis, and enhances the limited anti-metastatic effect of bortezomib.

Key findings

  • miR-33b-3p was significantly reduced in prostate cancer tissues, and low expression correlated with poor overall survival (log-rank p=0.024414). In clinical samples, miR-33b-3p was the major mature isoform in normal prostate and tumor tissues (n=27).
  • Overexpression of miR-33b-3p inhibited migration and invasion in highly metastatic PC-3M-1E8 cells, whereas miR-33b-3p inhibition promoted these processes in lowly metastatic PC-3M-2B4 cells. In vivo, control mice showed lung metastasis and more lymph node metastases (7 luminescent lymph nodes in 3 mice) than the miR-33b-3p group (2 luminescent lymph nodes in 2 mice).
  • DOCK4 was validated as a direct target of miR-33b-3p; miR-33b-3p decreased DOCK4 mRNA and protein, and DOCK4 restoration rescued miR-33b-3p inhibition of migration and invasion. TCGA data showed DOCK4 was upregulated in primary prostate tumors versus normal tissues (median 7.73 vs 5.39; p=8.68E-11), and high DOCK4 was associated with shorter disease-free survival (p=0.032).
  • Bortezomib downregulated miR-33b-3p, and miR-33b-3p overexpression enhanced bortezomib suppression of migration and invasion. In vivo lung metastasis after treatment was: control PBS 4/4, control bortezomib 4/5, miR-33b-3p PBS 1/4, and miR-33b-3p plus bortezomib 2/5.

Methods

  • In vitro assays used prostate cancer cell lines (LNCaP, PC3, PC-3M-1E8, PC-3M-2B4) with RT-qPCR, MTT, Western blotting, wound healing, Transwell migration/invasion, and dual-luciferase reporter assays. RNA-seq was performed in PC-3M-1E8 cells after miR-33b-3p overexpression (GEO accession GSE183428).
  • In vivo metastasis studies used BALB/c nude mice injected via tail vein with PC-3M-1E8-luciferase cells (1.5 × 10^6); bortezomib was given at 0.5 mg/kg body weight intraperitoneally twice weekly for four weeks.
  • Statistical analysis used two-tailed Student’s t-test, Kaplan-Meier method with log-rank test for TCGA overall survival, DESeq2 for RNA-seq differential expression (adjusted P<0.05), and clusterProfiler for GO enrichment (corrected P<0.05).

Limitations

  • The paper states that it cannot eliminate the influence of other biological processes, such as angiogenesis and endothelial cell migration identified by RNA-seq, on metastasis.
  • The paper notes it is unclear how prostate cancer cells select miR-33b-3p as the dominant mature form.
  • Evident from the text: the in vivo experiments used small groups (n=5 per group, n=4 for PBS; 2 mice died after two weeks of bortezomib treatment), and the clinical tissue comparison used a limited sample (n=27).

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

Integrity signals

Registry

Crossref · 10.3389/fonc.2021.740452

Cites

41 of 41 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

19 of 25 cited sources checked · 9 supported · 1 flagged · accuracy not yet measured

  • Premisecitation

    Decreased level of circulating miR-33b-3p was detected in patients with upper tract urothelial carcinoma in comparison with normal control group.

    “In addition, decreased level of circulating miR-33b-3p was detected in patients with upper tract urothelial carcinoma in comparison with normal control group (36), supporting the tumor suppressive role of miR-33b-3p.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [36] Tao, 2015, Identification of Circulating microRNA Signatures for Upper Tract Urothelial Carcinoma Detection, Mol Med Rep source

      The Discussion (page unavailable) states the opposite: serum miR-33b expression was enhanced in UTUC cases. It contrasts this with lower plasma miR-33b in bladder cancer cases, not UTUC cases. (LLM, conf=0.90)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
  • Premisecitation

    Bortezomib induces downregulation of miR-33b-3p.

    “downregulation of miR-33b-3p was induced by bortezomib, the clinically used proteasome inhibitor”
    • Also stated in: § Introduction · plain
      “Our previous studies showed that miR-33b-3p was downregulated in prostate cancer in response to proteasome inhibition (14).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [14] Wang, 2018, Sp1 Suppresses miR-3178 to Promote the Metastasis Invasion Cascade via Upregulation of TRIOBP, Mol Ther Nucleic Acids source

      The Materials and Methods (Microarray; page unavailable) describe bortezomib treatment, and the Results (Sp1 Is a Transcriptional Suppressor of miR-3178; page unavailable) report that treatment downregulated SP1 and upregulated miR-3178. Searches for miR-33b-3p and bortezomib-induced miRNA downregulation found no passage stating what happened to miR-33b-3p. (LLM, conf=0.76)

      Experimental — accuracy not yet measured
  • Premisecitation

    Proteasome inhibitors failed to benefit to patients with solid tumors for some reasons.

    “However, proteasome inhibitors failed to benefit to patients with solid tumors for some reasons (41).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [41] Manasanch, 2017, Proteasome Inhibitors in Cancer Therapy, Nat Rev Clin Oncol source
  • Findingown data

    miR-33b-5p is almost undetected in prostate cancer cell lines.

    “while miR-33b-5p was almost undetected ( Figure 1B ).”
    Quote in the paperSubstantial claim
  • Findingown data

    PC-3M-1E8 cells with low miR-33b-3p have higher DOCK4 protein than PC-3M-2B4 cells.

    “PC-3M-1E8 cells with low level of miR-33b-3p had high protein level of DOCK4 in relative to PC-3M-2B4 cells ( Figure 5D )”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 24
  • May combine two claims. 12
  • The quote only partly states this claim. 2

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

    Premisecitation

    Overexpression of DOCK4 in placental cytotrophoblasts increased the invasiveness of these cells.

    “Overexpression of DOCK4 in placental cytotrophoblasts increased the invasiveness of these cells (38).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [38] McNally, 2020, Up-Regulated Cytotrophoblast DOCK4 Contributes to Over-Invasion in Placenta Accreta Spectrum, Proc Natl Acad Sci USA source

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

    Premisecitation

    Downregulation of miR-33b-3p was found associated with aggressive phenotype of bladder cancer.

    “On the other hand, downregulation of miR-33b-3p was found associated with aggressive phenotype of bladder cancer (22).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [22] Inamoto, 2018, A Panel of MicroRNA Signature as a Tool for Predicting Survival of Patients With Urothelial Carcinoma of the Bladder, Dis Markers source

      The Abstract Results report that miR-33b-3p was deregulated in aggressive versus nonaggressive bladder cancer and classify it as protective in the nine-miRNA signature. They do not specify that it was downregulated in aggressive tumors. The main Results section also says miR-33b had no significant individual association with the high-risk feature (page not given in our copy). (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim.

    Premisecitation

    miR-33b-5p is predominantly upregulated in multiple myeloma after proteasome inhibitor treatment.

    “It drew our attention that miR-33b-5p was predominantly upregulated in multiple myeloma post treatment with proteasome inhibitor (15, 16).”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [15] Hao, 2015, Low Serum miR-19a Expression as a Novel Poor Prognostic Indicator in Multiple Myeloma, Int J Cancer source

      The Results (Validation of candidate miRNAs using RT-qPCR; page unavailable) report increased serum miR-33b in newly diagnosed multiple myeloma patients compared with healthy donors. They do not identify the measured form as miR-33b-5p or show that it was upregulated after proteasome inhibitor treatment. The paper’s bortezomib-treatment analysis concerns miR-19a, not miR-33b. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [16] Tian, 2012, Investigational Agent MLN9708/2238 Targets Tumor-Suppressor Mir33b in MM Cells, Blood source

      The section “MLN2238 induces miR33b and MM patient tumor cells express low constitutive levels of miR33b” reports that miR33b was among the most upregulated miRNAs after MLN2238 treatment of multiple myeloma cell lines (page unavailable). The paper calls it miR33b, not specifically miR-33b-5p, and tests the proteasome inhibitor MLN2238 rather than proteasome inhibitors generally. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

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

    Premisecitation

    Overexpression of miR-33b-3p enhanced cell proliferation and colony formation in gastric cancer.

    “Overexpression of miR-33b-3p enhanced cell proliferation and colony formation in gastric cancer (35), indicating the oncomir function of miR-33b-3p.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [35] Sexton, 2019, Targeting Nuclear Exporter Protein XPO1/CRM1 in Gastric Cancer, Int J Mol Sci source

      Results §2.5 reports that a miR-33b-3p mimic significantly enhanced cellular growth in two gastric cancer cell lines and affected colony formation in NCI-N87 cells. The text says colony formation was “influenced,” but does not state that it increased, so that part of the claim is not fully supported. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

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

    Premisecitation

    Upregulation of DOCK4 was found associated with metastases of breast and lung cancer.

    “Upregulation of DOCK4 was found associated with metastases of breast and lung cancer (39, 40).”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [39] Yu, 2015, TGF-β/Smad Signaling Through DOCK4 Facilitates Lung Adenocarcinoma Metastasis, Genes Dev source

      The Results and Discussion support the lung-cancer portion: DOCK4 is upregulated by TGF-β in lung adenocarcinoma cells, and the paper reports a role for DOCK4 in lung adenocarcinoma metastasis. They do not support the breast-cancer portion; the paper reports no TGF-β-induced DOCK4 expression in breast cancer cells and no correlation between DOCK4 expression and breast-cancer relapse. No page numbers are available in our copy. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [40] Westbrook, 2019, Identification and Validation of DOCK4 as a Potential Biomarker for Risk of Bone Metastasis Development in Patients With Early Breast Cancer, J Pathol source

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

    Premisecitation

    Both arms of miR-33b can have similar or opposite functions.

    “In some cases, they have similar function while in some cases; they work opposite (19).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [19] Zhang, 2019, microRNA Arm-Imbalance in Part From Complementary Targets Mediated Decay Promotes Gastric Cancer Progression, Nat Commun source

      The Discussion says that the two arms of a miRNA can have similar or different functions, and the Results demonstrate opposite functions for the two arms of miR-574 in gastric cancer. The Results section on expression patterns mentions miR-33b but does not establish whether its two arms have similar or opposite functions; the miR-33b-specific claim is unsupported. (LLM, conf=0.87)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim.

    Premisecitation

    miR-33b-3p functions as a tumor suppressor in some types of cancers.

    “miR-33b-3p also functions as tumor suppressor in some type of cancers (21, 22).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [21] Gao, 2019, Identifying TF-miRNA-mRNA Regulatory Modules in Nitidine Chloride Treated HCC Xenograft of Nude Mice, Am J Transl Res
    • cites [22] Inamoto, 2018, A Panel of MicroRNA Signature as a Tool for Predicting Survival of Patients With Urothelial Carcinoma of the Bladder, Dis Markers source

      The Results section (page not provided) includes miR-33b-3p among nine miRNAs previously reported to have oncogenic or antioncogenic roles. It does not identify which role belongs to miR-33b-3p or show that it functions as a tumor suppressor in any cancer type; it also reports no significant individual association for miR-33b in the bladder-cancer analysis. (LLM, conf=0.77)

      Experimental — accuracy not yet measured

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

    Premisecitation

    DOCK4 was first identified as a Rap GTPase activator that can enhance the formation of adherent junctions between cells, mutations of which was found to confer the loss of cell junction and an invasive phenotype in cancer.

    “It was first identified as a Rap GTPase activator that can enhance the formation of adherent junctions between cells, mutations of which was found to confer the loss of cell junction and an invasive phenotype in cancer (37).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [37] Yajnik, 2003, DOCK4, a GTPase Activator, is Disrupted During Tumorigenesis, Cell source

  • Classified as probably not a substantial claim.

    Premisecitation

    Proteasome inhibitor treatment alters miRNAs.

    “Proteasome inhibitor leads to alteration in not only the proteins but also the miRNAs (12, 13).”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [12] Manier, 2017, Prognostic Role of Circulating Exosomal miRNAs in Multiple Myeloma, Blood source

      The ‘Exosomal miRNAs and survival in MM’ section says serum was collected before bortezomib-and-dexamethasone therapy and analyzes baseline miRNAs as prognostic markers. The ‘Statistical analysis’ section likewise describes newly diagnosed, untreated patients. Neither passage establishes that proteasome inhibitor treatment alters miRNAs; searches for treatment-related miRNA changes found no such result in our copy. (LLM, conf=0.77)

      Experimental — accuracy not yet measured
    • cites [13] Łuczkowska, 2020, Molecular Mechanisms of Bortezomib Action: Novel Evidence for the miRNA-mRNA Interaction Involvement, Int J Mol Sci source

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

    Premisecitation

    miR-33b-3p targets CDKN1A (p21) and contributes to cisplatin-resistance in lung cancer.

    “It targets the well-known tumor suppressor CDKN1A (p21) and contributes to cisplatin-resistance in lung cancer (34).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [34] Xu, 2016, DNA Damage Responsive miR-33b-3p Promoted Lung Cancer Cells Survival and Cisplatin Resistance by Targeting P21(WAF1/CIP1), Cell Cycle source

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

    Premisecitation

    Bortezomib demonstrates great success against multiple myeloma.

    “The first-in-class proteasome inhibitor bortezomib demonstrates great success against multiple myeloma (4).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [4] Yang, 2009, Clinical Development of Novel Proteasome Inhibitors for Cancer Treatment, Expert Opin Investig Drugs source

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

    Premisecitation

    Both arms of miRNAs can be expressed as mature forms in vivo.

    “Both arms of the miRNAs can be expressed as a mature form in vivo (17, 18).”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [17] Guo, 2015, Evolutionary and Expression Analysis of miR-#-5p and miR-#-3p at the miRNAs/isomiRs Levels, BioMed Res Int source
    • cites [18] Medley, 2021, microRNA Strand Selection: Unwinding the Rules, Wiley Interdiscip Rev RNA source

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

    Findingown data

    miR-33b-5p is the major form in breast and lung cancer cell lines.

    “miR-33b-5p was the major form in breast and lung cancer cell lines ( Figure 1C ).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    PC-3M-1E8 cells extensively metastasize to lymph nodes and liver in control mice, and this is suppressed by miR-33b-3p overexpression.

    “PC-3M-1E8 cells extensively metastasized to the lymph nodes and liver in the control group, whereas it was significantly suppressed in miR-33b-3p group ( Figure 4D ).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Tail vein injection of PC-3M-1E8 cells into nude mice is a valid model of prostate cancer metastasis to lung and lymph nodes.

  • The quote only partly states this claim.

    Findingown data

    Over-expression of miR-33b-3p enhanced bortezomib effects on suppression of lung metastasis (2/5).

    “and over-expression of miR-33b-3p could enhanced bortezomib effects on suppression of lung metastasis (2/5).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Control group receiving PBS all developed lung metastasis (4/4), while control group receiving bortezomib developed lung metastasis in 4/5.

    “The summarize of H&E results showed that the control group receiving PBS all developed lung metastasis (4/4), while control group receiving bortezomib developed lung metastasis in 4/5.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Low expression level of miR-33b-3p was detected in patients with prostate cancer and associated with their shortened survival period.

    “Low expression level of miR-33b-3p was detected in patients with prostate cancer and associated with their shortened survival period.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Overexpression of wild type of DOCK4 promoted the migration and invasion of prostate cancer cells, supporting its function to mediate metastasis in prostate cancer.

    “In this study, overexpression of wild type of DOCK4 promoted the migration and invasion of prostate cancer cells, supporting its function to mediate metastasis in prostate cancer.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    miR-33b-3p suppressed the luciferase activity of the reporter containing the wild type 3' UTR of DOCK4 in PC-3M-1E8 cells, and this effect was abrogated with the mutated reporter.

    “Dual luciferase assays showed that miR-33b-3p suppressed the luciferase activity of the reporter containing the wild type 3’ UTR of DOCK4 in PC-3M-1E8 cells, and this effect was abrogated with the mutated reporter ( Figure 5F ).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Overexpression of miR-33b-3p suppressed whereas inhibition of miR-33b-3p promoted the migration and invasion abilities of cancer cells.

    “Overexpression of miR-33b-3p suppressed whereas inhibition of miR-33b-3p promoted the migration and invasion abilities of cancer cells.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    Under non-cytotoxic doses, bortezomib had no effect on inhibition of cell invasion, while overexpression of miR-33b-3p could improve bortezomib suppression on migration and invasion.

    “Under non-cytotoxic doses, bortezomib had no effect on inhibition of cell invasion, while overexpression of miR-33b-3p could improve bortezomib suppression on migration and invasion.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    miR-33b-3p is recognized as an oncogenic or tumor suppressive molecule depending on different cell context.

    “miR-33b-3p is recognized as an oncogenic or tumor suppressive molecule depending on different cell context.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    As a combination regimen, bortezomib did not improve prostate cancer patients' response to docetaxel.

    “As a combination regimen, bortezomib was found not able to improve prostate cancer patients’ response to docetaxel, a standard treatment for mCRPC (5, 6).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [5] Hainsworth, 2007, Weekly Docetaxel and Bortezomib as First-Line Treatment for Patients With Hormone-Refractory Prostate Cancer: A Minnie Pearl Cancer Research Network Phase II Trial, Clin Genitourin Cancer source
    • cites [6] Rescigno, 2012, New Perspectives in the Therapy of Castration Resistant Prostate Cancer, Curr Drug Targets source

  • Classified as probably not a substantial claim. The quote only partly states this claim.

    Study design and conductown data

    Data in Figures 1-3 are representative of at least three independent experiments.

    “Data (A–C) are representative of at least three independent experiments.”
    • Also stated in: § miR-33b-3p Inhibits Prostate Cancer Cells Proliferation · plain
      “Data are representative of three independent experiments.”
    • Also stated in: § miR-33b-3p Inhibits Prostate Cancer Cells Migration and Invasion · plain
      “Data are representative of at least three independent experiments.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    miR-33b-5p functions as a tumor suppressor in prostate cancer.

    “It has been shown that miR-33b-5p functions as tumor suppressor in prostate cancer (20).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [20] Zhao, 2019, CUL4B/miR-33b/C-MYC Axis Promotes Prostate Cancer Progression, Prostate source

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

    Interpretationcitation

    miR-33b-3p selection in prostate cancer might depend on the prostate cell type.

    “Given that miR-33b-5p could be detected as a major mature form in other type of cancer tissues (29, 30), we deduced that miR-33b-3p selection in prostate cancer might depend on the prostate cell type.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [29] Li, 2015, Downregulated miR-33b is a Novel Predictor Associated With Disease Progression and Poor Prognosis in Multiple Myeloma, Leuk Res source
    • cites [30] Wang, 2020, MicroRNA-33b Regulates Hepatocellular Carcinoma Cell Proliferation, Apoptosis, and Mobility via Targeting Fli-1-Mediated Notch1 Pathway, J Cell Physiol source

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

    Study design and conductnone given

    Animal studies were performed according to a protocol approved by the Animal Care and Use Committee of Harbin Institute of Technology.

    “All studies in animals were performed according to protocol approved by the Animal Care and Use Committee of Harbin Institute of Technology.”
    Quote in the paperNot a substantial claim

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

    Study design and conductnone given

    Constructed plasmids were confirmed by sequencing.

    “All these constructed plasmids were confirmed by sequencing.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Bortezomib had limited effect on metastasis suppression in prostate cancer which can be enhanced by miR-33b-3p.

    “This result indicates that bortezomib had limited effect on metastasis suppression in prostate cancer which can be enhanced by miR-33b-3p.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Knockdown efficiency or overexpression level was confirmed by RT-qPCR.

    “The knockdown efficiency or overexpression level was confirmed by RT-qPCR.”
    Quote in the paperSubstantial claim

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

    Study design and conductnone given

    The animal study was reviewed and approved by Animal Care and Use Committee, Harbin Institute of Technology.

    “The animal study was reviewed and approved by Animal Care and Use Committee, Harbin Institute of Technology”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Proteasome inhibitor bortezomib leads to insufficient inhibition on cell invasion due to miR-33b-3p downregulation, which can be overcome by overexpression of miR-33b-3p.

    “Proteasome inhibitor bortezomib leads to insufficient inhibition on cell invasion due to miR-33b-3p downregulation, which can be overcome by overexpression of miR-33b-3p in prostate cancer.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Data (A-H) are representative of three independent experiments.

    “Data (A–H) are representative of three independent experiments.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Data (B, F-J) are representative of at least three independent experiments.

    “Data (B, F–J) are representative of at least three independent experiments.”
    Quote in the paperSubstantial claim
34 of 34

  • The paper relies on this without support.

    Bortezomib alone has limited efficacy in solid tumors including prostate cancer.

    “However, limited efficacy of bortezomib alone was observed in solid tumors including prostate cancer.”

  • The paper relies on this without support.

    Tail vein injection of PC-3M-1E8 cells into nude mice is a valid model of prostate cancer metastasis to lung and lymph nodes.

    “The mice were inoculated with PC-3M-1E8-luciferase cells (1.5 × 106) through tail vein, and luminescent signal was monitored every week.”

  • The paper relies on this without support.

    The TCGA prostate adenocarcinoma dataset is representative for overall survival analysis of prostate cancer patients.

    “The overall survival curves of patients from TCGA was plotted by Kaplan-Meier method and the log-rank test.”
3 of 3

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.

  • MTT-assay transfection duration differs

    Major

    The MTT methods say cells were transfected for 24 hours before plating, while the Figure 2 caption says transfection lasted 48 hours before the MTT assay.

  • Luciferase-assay transfection duration differs

    Minor

    The methods specify a 48-hour co-transfection, whereas the Figure 5 caption specifies 24 hours for the luciferase reporter assay.

2 of 2

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Related

Authors
Mei, Y., Li, K., Zhang, Z., Li, M., Yang, H., Wang, H., Huang, X., Li, X., Shi, S., & Yang, H.
Affiliations
  • Harbin Institute of Technology (CN)
  • Fourth Affiliated Hospital of Harbin Medical University (CN)
ORCID
Venue
Frontiers in Oncology
Publisher
Frontiers Media SA
Published
2021-11-03
Volume
11
Pages
740452-740452
ISSN
2234-943X (ISSN-L)
DOI
10.3389/fonc.2021.740452
PMC
PMC8595470
OpenAlex
W3210242492
Semantic Scholar
40e8072bea9a2168e171ad7765f64751262947ea
Cited by
10
References
41
Citations by year
2026: 1 · 2025: 2 · 2024: 1 · 2023: 6
FWCI
0.58
Type
journal article
Language
en
Open access
Licence
Locations
  • Frontiers in Oncology (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • PubMed Central (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • National Natural Science Foundation of China (81872439)
  • Natural Science Foundation of Heilongjiang Province (LH2020H072)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › MicroRNA in disease regulation
  • Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Prostate Cancer Treatment and Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Cancer-related molecular mechanisms research
Keywords
DOCK4, prostate cancer, metastasis, tumor suppressor microRNA, cell migration, cell invasion, bortezomib, proteasome inhibitor resistance, castration-resistant prostate cancer, overall survival, lung metastasis, lymph node metastasis

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 2026-10-19.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-19.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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