Modulation of K-Ras-Dependent Lung Tumorigenesis by MicroRNA-21

In the paper

“Recently, miR-21 expression levels have proven useful prognostic markers in non-small cell lung cancer (Markou et al., 2008; Yanaihara et al., 2006).”

What the sources say

• Supported

  The discussion reports that mature miR-21 overexpression in NSCLC was associated with lung-cancer death and was an independent prognostic factor in multivariate analysis. The authors caution that the small number of events requires further confirmation, so the finding should not be read as a validated clinical test. (LLM, conf=0.88)

  cites Markou et al., 2008 source
• Partly supported

  The Results report that high hsa-mir-21 expression was associated with significantly worse survival in lung adenocarcinoma patients. They do not establish miR-21 as a validated prognostic marker across non-small cell lung cancer: the reported prognostic validation focused on other miRNAs. (LLM, conf=0.88)

  cites Yanaihara et al., 2006 sourceExperimental — accuracy not yet measured

In the paper

“The level of miR-21 expression in sputum distinguishes NSCLC patients from cancer-free controls with a greater sensitivity than conventional cytology (Xie et al., 2009).”

What the sources say

• Supported

  The Results section, under “Comparison of cytology and measurement of altered miRNA expression in sputum,” reports 69.66% sensitivity for sputum miR-21 measurement versus 47.82% for conventional sputum cytology. The study examined sputum from 23 NSCLC patients and 17 cancer-free subjects, matching the claimed comparison. (LLM, conf=0.95)

  cites Xie et al., 2009 source

In the paper

“Several components of the PI3K pathway, including PTEN and PIK3R1, have been suggested as miR-21 target genes (Meng et al., 2007); however, miR-21 over-expression did not alter PTEN and PIK3R1 protein expression or Akt phosphorylation (Figure S3B).”

What the sources say

• Partly supported

  The Results identify PTEN as a miR-21 target, and the Discussion places PTEN in the PI3K pathway. The passages do not identify PIK3R1 as a miR-21 target. The statement that over-expression did not alter protein expression or Akt phosphorylation is attributed to the citing paper’s Figure S3B, not to Meng et al. (LLM, conf=0.87)

  cites Meng et al., 2007 sourceExperimental — accuracy not yet measured

In the paper

“Targeted deletion of miR-21 in RKO and DLD1 colon cancer cells revealed miR-21 contributes to tumorigenesis through compromising cell cycle progression and DNA damage-induced checkpoint function through the Cdc25a target gene (Wang et al., 2009).”

What the sources say

• Partly supported

  The Results report targeted miR-21 deletion in RKO and DLD1 cells, and the Discussion links miR-21, Cdc25A, cell-cycle progression, and checkpoint activation. However, the Discussion describes a contribution to tumorigenesis as a possibility, not a demonstrated outcome; the claim's “revealed” overstates that conclusion. (LLM, conf=0.88)

  cites Wang et al., 2009 sourceExperimental — accuracy not yet measured

In the paper

“As well, epidermal growth factor receptor (EGFR) and HER2/neu signaling positively regulates miR-21 expression in human lung and breast carcinoma cell lines, respectively (Huang et al., 2009; Seike et al., 2009).”

What the sources say

• Supported

  The paired citations and “respectively” attribute the HER2/neu finding in breast carcinoma cells to Huang et al. In “Ectopic Expression of HER2/neu Induces miR-21 Upregulation” (Fig. 1A; page not provided), the paper reports that HER2/neu expression increased miR-21 in a human breast cancer cell line. The EGFR finding in lung cells is not attributed to this source. (LLM, conf=0.94)

  cites Huang et al., 2009 source
• ?Not checked — no full text of the sourcecites Seike et al., 2009 source

In the paper

“Zhang et al. showed in a human gastric cancer cell line that forced over-expression of miR-21 enhanced tumor proliferation and invasion”

What the sources say

• Supported

  In the Results sections on proliferation and invasion (page numbers not provided), the paper reports that transfecting AGS human gastric cancer cells with a miR-21 expression construct significantly increased proliferation and strengthened invasion. This matches the claim about forced over-expression in a human gastric cancer cell line. (LLM, conf=0.94)

  cites Zhang et al., 2008 source

In the paper

“SPRY2, in turn, negatively regulates Ras/MEK/ERK signaling and is a tumor suppressor in NSCLC in both mice (Minowada and Miller, 2004; Minowada and Miller, 2009; Shaw et al., 2007) and humans (Sutterluty et al., 2007).”

What the sources say

• ?Not checked — no full text of the sourcecites Minowada and Miller, 2004 source
• Partly supported

  The study summary and Discussion (page unavailable) report fewer and smaller urethane-induced lung tumors in mice overexpressing Sprouty 2, supporting a tumor-suppressive effect in that mouse model. The Discussion says the findings are consistent with antagonism of Ras signaling, but the mechanism remains unclear; this paper does not demonstrate inhibition of MEK/ERK signaling. The citing sentence attributes the human NSCLC portion to a separate citation, not to this paper. (LLM, conf=0.83)

  cites Minowada and Miller, 2009 sourceExperimental — accuracy not yet measured
• Supported

  The Negative feedback signaling in development section reports that Spry-2 inhibits MAPK activation in K-ras G12D mouse lungs. The tumor-suppression section concludes that Spry-2 limits K-ras-driven mouse lung tumor development; a correction in Additional information says its revised results do not change that conclusion. The citing sentence attributes the human finding to Sutterluty et al., not to this paper. (LLM, conf=0.90)

  cites Shaw et al., 2007 source

In the paper

“All tumors from the survival cohort were analyzed on H&E sections and categorized as hyperplasia, atypical adenomatous hyperplasia, adenoma, adenoma with typia, and adenocarcinoma according to the Mouse Models of Human Cancer Consortium recommendations.(Nikitin et al., 2004)”

What the sources say

• Partly supported

  The Development of Recommendations section says the consortium prepared and reviewed H&E-stained sections, and the classification defines hyperplasia, atypical adenomatous hyperplasia, adenoma, and adenocarcinoma. The cited paper does not identify “adenoma with typia” as a recommended category. The survival-cohort analysis describes the citing authors’ own work, not an analysis reported by Nikitin et al. (LLM, conf=0.85)

  cites Nikitin et al., 2004 sourceExperimental — accuracy not yet measured

In the paper

“knock-down of miR-21 resulted in a marked reduction in proliferation and increase in apoptosis (Zhang et al., 2008).”

What the sources say

• Supported

  The Abstract states that inhibiting miR-21 in AGS human gastric cancer cells significantly reduced proliferation and increased apoptosis. The ‘miR-21 Increases Cell Proliferation and Inhibits Cell Apoptosis’ section reports both effects after transfection with an anti-miR-21 inhibitor. (LLM, conf=0.95)

  cites Zhang et al., 2008 source

In the paper

“Methods have been developed to manipulate miRNA function pharmacologically, facilitating the development of new cancer therapeutic strategies (Hutvagner et al., 2004; Krutzfeldt et al., 2005).”

What the sources say

• Partly supported

  The Results and Discussion report that 2′-O-methyl oligonucleotides inhibit specific miRNAs and can be used to study their function in C. elegans. The paper presents them as a research tool; it does not establish that they facilitate new cancer therapeutic strategies. (LLM, conf=0.87)

  cites Hutvagner et al., 2004 sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites Krutzfeldt et al., 2005 source

In the paper

“RECK, Cdc25a, Map2k3, NfiB, Trp63 and Ski have been shown to be miR-21 target genes in vitro, but only RECK showed decreased protein levels in the CAG-miR-21;K-rasLA2 tumors (Figure S3A).”

In the paper

“MiR21−/−;K-rasLA2 mice all develop lung tumors, but show an increased incidence of thymic lymphoma (Figure 2F).”

In the paper

“Caspase 3 and K-ras do not contain miR-21 sites in their 3′ UTR and the 3′ UTR luciferase reporter activity is not suppressed by miR-21 (Figure 3B).”

In the paper

“The decrease in Spry1, Spry2, and Btg2 in CAG-miR-21;K-rasLA2 tumors correlates with increased Ras pathway activity, shown by increased ERK phosphorylation (Figure 4C).”

In the paper

“We show miR-21 dependent repression of the mouse Apaf1 3′ UTR reporter; however, the miR-21 site in the human APAF1 3′ UTR is conserved in primates but not conserved in the mouse.”

In the paper

“adult male CAG-miR-21 mice showed no signs of heart failure compared to littermate controls (Figure S1E)(van Rooij et al., 2006; van Rooij et al., 2008).”

In the paper

“Apaf1, Pdcd4, Faslg, and RhoB were validated as direct miR-21 target genes by luciferase reporter assays; however, caspase 3 was not directly regulated by miR-21 (Figure 3B).”

In the paper

“MiR-21 over-expression increased the incidence of all tumor grades without increasing the rate of conversion to adenocarcinoma, suggesting that miR-21 participates in tumor promotion rather than progression and metastasis in this model (Figure 1J and 1K).”

In the paper

“Unlike K-rasLA1;p53−/− compound mutant mice (Johnson et al., 2001), we did not observe an increased tumor spectrum or increased metastasis in the CAG-miR-21;K-rasLA2 mutant mice.”

In the paper

“Although miR-21 function has been studied in vitro using cancer cell lines, the role of miR-21 in tumor development in vivo is unknown.”

In the paper

“MiR-21 drives tumorigenesis through inhibition of negative regulators of the Ras/MEK/ERK pathway and inhibition of apoptosis.”

In the paper

“A large scale survey to determine the miRNA signature of 540 tumor samples including lung, breast, stomach, prostate, colon, and pancreatic tumors and their respective normal adjacent tissue revealed miR-21 was the only miRNA up-regulated in all these tumors (Volinia et al., 2006).”

What the sources say

• ?Not checked — no full text of the sourcecites Volinia et al., 2006 source

In the paper

“Further miRNA profiling in tumor samples and cancer cell lines show increased miR-21 expression in glioblastoma (Chan et al., 2005; Ciafre et al., 2005), head and neck carcinomas (Tran et al., 2007), ovarian cancer (Iorio et al., 2007), B-cell lymphoma (Lawrie et al., 2007), hepatocellular (Meng et al., 2007), and cervical carcinoma (Lui et al., 2007).”

What the sources say

• ?Not checked — no full text of the sourcecites Chan et al., 2005 source
• ?Not checked — no full text of the sourcecites Ciafre et al., 2005 source
• ?Not checked — no full text of the sourcecites Tran et al., 2007 source

In the paper

“CAG-miR-21 transgenic mice were viable, fertile and born in expected Mendelian ratios.”

In the paper

“Knock-down of miR-21 in the metastatic breast cancer MD-MBA-231 cells reduced invasion and metastasis (Zhu et al., 2008).”

What the sources say

• ?Not checked — no full text of the sourcecites Zhu et al., 2008 source

In the paper

“Homozygous miR-21 knock-out mice are viable, fertile, and born in expected Mendelian ratios without any gross phenotypic differences compared to wild type or heterozygous littermates, and without a cardiac phenotype (D.P., E.V.R. and E.N.O., manuscript in preparation).”

In the paper

“These data illustrate that miR-21 over-expression decreases the protein expression of four miR-21 target genes that are involved in apoptosis thus promoting survival.”

In the paper

“miR-21 expression was induced by AP-1 in response to Ras activation, and miR-21 mediated Ras-dependent downregulation of Pdcd4 (Talotta et al., 2009)”

What the sources say

• ?Not checked — no full text of the sourcecites Talotta et al., 2009 source

In the paper

“Knockdown of miR-21 in cultured glioblastoma cells activates caspases leading to apoptotic cell death, suggesting miR-21 is an anti-apoptotic factor (Chan et al., 2005).”

What the sources say

• ?Not checked — no full text of the sourcecites Chan et al., 2005 source

In the paper

“K-rasLA2 mice develop multi-focal lung tumors with 100% penetrance, and less frequently develop thymic lymphomas and skin papillomas (Johnson et al., 2001).”

What the sources say

• ?Not checked — no full text of the sourcecites Johnson et al., 2001 source

In the paper

“These data suggest that miR-21 over-expression in human tumors does not simply reflect cancer pathology, but instead enhances aspects of the pathology of NSCLC.”

In the paper

“Previously, an autoregulatory loop connecting miR-21 and Ras activation through AP-1 was illustrated in a rat thyroid cell system (Talotta et al., 2009).”

What the sources say

• ?Not checked — no full text of the sourcecites Talotta et al., 2009 source

In the paper

“These data show that miR-21 over-expression decreases the protein expression of four miR-21 target genes that are tumor suppressors and negative regulators of the Ras/MEK/ERK pathway resulting in a concomitant increased ERK activity.”

In the paper

“In breast cancer MCF-7 cells, miR-21 knock-down results in suppression of cell growth in vitro and tumor growth in xenografts (Si et al., 2007).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Si et al., 2007

In the paper

“All mice used in these studies were of mixed genetic backgrounds and all comparisons were performed on littermate controls.”

In the paper

“PDCD4 is a pro-apoptotic tumor suppressor gene and has been verified as a miR-21 target in human colorectal and breast cancer cell lines (Afonja et al., 2004; Asangani et al., 2007; Bitomsky et al., 2008; Frankel et al., 2007; Lu et al., 2008; Zhang et al., 2006).”

What the sources say

• ?Not checked — no full text of the sourcecites Afonja et al., 2004 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Asangani et al., 2007
• ?Not checked — no full text of the sourcecites Bitomsky et al., 2008 source

In the paper

“In laryngeal carcinoma, miR-21 targets BTG2 (Liu et al., 2009), a p53 target gene, recently shown to suppress oncogenic Ras activity by reducing the GTP bound, active state (Buganim et al., 2010).”

What the sources say

• ?Not checked — no full text of the sourcecites Liu et al., 2009 source
• ?Not checked — no full text of the sourcecites Buganim et al., 2010 source

In the paper

“Knock-down of miR-21 in glioblastoma cell lines triggers the activation of caspases and increases apoptosis (Chan et al., 2005).”

What the sources say

• ?Not checked — no full text of the sourcecites Chan et al., 2005 source

In the paper

“RhoB promotes growth inhibition and induces apoptosis in cancer cells (Kim et al., 2009)”

What the sources say

• ?Not checked — no full text of the sourcecites Kim et al., 2009 source

In the paper

“Although the reductions in protein levels of individual miR-21 targets appear modest with miR-21 over-expression, collectively this diminution of tumor suppressor activity allows for more robust tumor formation through relieving multiple nodes of inhibition of the Ras/MEK/ERK pathway, thus facilitating tumor proliferation.”

In the paper

“We show that Ras activation increases miR-21 expression and in turn decreasing the expression of Spry2.”

In the paper

“miR-21 modulates several components critical to NSCLC pathogenesis through both relieving antagonism of the Ras pathway and reducing apoptotic effectors (Figure 7).”

In the paper

“RhoB expression is down-regulated in human NSCLC suggesting a role as a tumor suppressor gene (Sato et al., 2007).”

What the sources say

• ?Not checked — no full text of the sourcecites Sato et al., 2007 source

In the paper

“Relieving miR-21 inhibition of pro-apoptotic genes could provide a means to augment the effect of current chemotherapy.”

In the paper

“MiR-21 targets SPRY2 in cardiomyocytes and SW480 colon cancer cells, enhancing cell migration (Sayed et al., 2008).”

What the sources say

• ?Not checked — no full text of the sourcecites Sayed et al., 2008 source

In the paper

“Our results show that miR-21 expression modulates tumor number, incidence and size in a mouse lung cancer model initiated by oncogenic K-rasG12D, consistent with miR-21 functioning as a tumor promoter.”

In the paper

“Pdcd4 functions both as an inducer of apoptosis and a suppressor of AP-1 activity (Hwang et al., 2007).”

What the sources say

• ?Not checked — no full text of the sourcecites Hwang et al., 2007 source

In the paper

“Loss of PDCD4 expression in human lung cancer correlates with higher grade and disease stage (Chen et al., 2003).”

What the sources say

• ?Not checked — no full text of the sourcecites Chen et al., 2003 source