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CFIm25 links alternative polyadenylation to glioblastoma tumour suppression.

Masamha CP, Xia Z, Yang J, Albrecht TR, Li M, Shyu AB, Li W, Wagner EJ - Nature (2014)

Bottom Line: Applying a regression model on standard RNA-sequencing data for novel APA events, we identified at least 1,450 genes with shortened 3' UTRs after CFIm25 knockdown, representing 11% of significantly expressed mRNAs in human cells.Marked increases in the expression of several known oncogenes, including cyclin D1, are observed as a consequence of CFIm25 depletion.Downregulation of CFIm25 expression in glioblastoma cells enhances their tumorigenic properties and increases tumour size, whereas CFIm25 overexpression reduces these properties and inhibits tumour growth.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, Texas 77030, USA [2].

ABSTRACT
The global shortening of messenger RNAs through alternative polyadenylation (APA) that occurs during enhanced cellular proliferation represents an important, yet poorly understood mechanism of regulated gene expression. The 3' untranslated region (UTR) truncation of growth-promoting mRNA transcripts that relieves intrinsic microRNA- and AU-rich-element-mediated repression has been observed to correlate with cellular transformation; however, the importance to tumorigenicity of RNA 3'-end-processing factors that potentially govern APA is unknown. Here we identify CFIm25 as a broad repressor of proximal poly(A) site usage that, when depleted, increases cell proliferation. Applying a regression model on standard RNA-sequencing data for novel APA events, we identified at least 1,450 genes with shortened 3' UTRs after CFIm25 knockdown, representing 11% of significantly expressed mRNAs in human cells. Marked increases in the expression of several known oncogenes, including cyclin D1, are observed as a consequence of CFIm25 depletion. Importantly, we identified a subset of CFIm25-regulated APA genes with shortened 3' UTRs in glioblastoma tumours that have reduced CFIm25 expression. Downregulation of CFIm25 expression in glioblastoma cells enhances their tumorigenic properties and increases tumour size, whereas CFIm25 overexpression reduces these properties and inhibits tumour growth. These findings identify a pivotal role of CFIm25 in governing APA and reveal a previously unknown connection between CFIm25 and glioblastoma tumorigenicity.

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Reduction in CFIm25 expression levels enhances LN229 tumor size and weightLN229 xenograft tumors were isolated from nude mice on day 40 post implantation and measured for volume (a) and weight (b) (n=10). LN-229-shCon. represents control lentiviral transduced cells while LN229-shCFIm25 represents cells transduced with a lentivirus that expresses shRNA targeting CFIm25.
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Figure 9: Reduction in CFIm25 expression levels enhances LN229 tumor size and weightLN229 xenograft tumors were isolated from nude mice on day 40 post implantation and measured for volume (a) and weight (b) (n=10). LN-229-shCon. represents control lentiviral transduced cells while LN229-shCFIm25 represents cells transduced with a lentivirus that expresses shRNA targeting CFIm25.

Mentions: To formally test if altering CFIm25 expression can modulate GBM tumorigenic properties, we screened a panel of GBM cell lines and observed that U251 cells naturally express lower levels of CFIm25 compared to LN229 cells, which express higher levels (Fig. 4c). To raise CFIm25 levels in U251 cells, we created cell lines stably expressing either myc-tagged CFIm25 or GFP as a control. In parallel, we used RNAi to reduce CFIm25 levels in LN229 cells (Fig. 4c). We observed a significant reduction in anchorage-dependent growth and cellular invasion in U251 cells overexpressing CFIm25 compared to the GFP control whereas reducing CFIm25 in LN229 cells caused an increase in both of these properties (Extended Data Fig. 7). To determine if the altered in vitro properties of GBM cells affected tumor growth kinetics in vivo, we utilized a subcutaneous xenograft model. Increased expression of CFIm25 in U251 resulted in a dramatic reduction in tumor growth and decreased tumor cell proliferation (Fig. 4d and Extended Data Fig. 8). In contrast, depletion of CFIm25 in LN229 cells caused a profound increase in tumor size (Fig. 4f and Extended Data Fig. 9). Collectively, these results uncover a tumor suppressive property of CFIm25 in GBM that is likely mediated through its broad repression of APA-dependent mRNA 3′UTR shortening.


CFIm25 links alternative polyadenylation to glioblastoma tumour suppression.

Masamha CP, Xia Z, Yang J, Albrecht TR, Li M, Shyu AB, Li W, Wagner EJ - Nature (2014)

Reduction in CFIm25 expression levels enhances LN229 tumor size and weightLN229 xenograft tumors were isolated from nude mice on day 40 post implantation and measured for volume (a) and weight (b) (n=10). LN-229-shCon. represents control lentiviral transduced cells while LN229-shCFIm25 represents cells transduced with a lentivirus that expresses shRNA targeting CFIm25.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128630&req=5

Figure 9: Reduction in CFIm25 expression levels enhances LN229 tumor size and weightLN229 xenograft tumors were isolated from nude mice on day 40 post implantation and measured for volume (a) and weight (b) (n=10). LN-229-shCon. represents control lentiviral transduced cells while LN229-shCFIm25 represents cells transduced with a lentivirus that expresses shRNA targeting CFIm25.
Mentions: To formally test if altering CFIm25 expression can modulate GBM tumorigenic properties, we screened a panel of GBM cell lines and observed that U251 cells naturally express lower levels of CFIm25 compared to LN229 cells, which express higher levels (Fig. 4c). To raise CFIm25 levels in U251 cells, we created cell lines stably expressing either myc-tagged CFIm25 or GFP as a control. In parallel, we used RNAi to reduce CFIm25 levels in LN229 cells (Fig. 4c). We observed a significant reduction in anchorage-dependent growth and cellular invasion in U251 cells overexpressing CFIm25 compared to the GFP control whereas reducing CFIm25 in LN229 cells caused an increase in both of these properties (Extended Data Fig. 7). To determine if the altered in vitro properties of GBM cells affected tumor growth kinetics in vivo, we utilized a subcutaneous xenograft model. Increased expression of CFIm25 in U251 resulted in a dramatic reduction in tumor growth and decreased tumor cell proliferation (Fig. 4d and Extended Data Fig. 8). In contrast, depletion of CFIm25 in LN229 cells caused a profound increase in tumor size (Fig. 4f and Extended Data Fig. 9). Collectively, these results uncover a tumor suppressive property of CFIm25 in GBM that is likely mediated through its broad repression of APA-dependent mRNA 3′UTR shortening.

Bottom Line: Applying a regression model on standard RNA-sequencing data for novel APA events, we identified at least 1,450 genes with shortened 3' UTRs after CFIm25 knockdown, representing 11% of significantly expressed mRNAs in human cells.Marked increases in the expression of several known oncogenes, including cyclin D1, are observed as a consequence of CFIm25 depletion.Downregulation of CFIm25 expression in glioblastoma cells enhances their tumorigenic properties and increases tumour size, whereas CFIm25 overexpression reduces these properties and inhibits tumour growth.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, Texas 77030, USA [2].

ABSTRACT
The global shortening of messenger RNAs through alternative polyadenylation (APA) that occurs during enhanced cellular proliferation represents an important, yet poorly understood mechanism of regulated gene expression. The 3' untranslated region (UTR) truncation of growth-promoting mRNA transcripts that relieves intrinsic microRNA- and AU-rich-element-mediated repression has been observed to correlate with cellular transformation; however, the importance to tumorigenicity of RNA 3'-end-processing factors that potentially govern APA is unknown. Here we identify CFIm25 as a broad repressor of proximal poly(A) site usage that, when depleted, increases cell proliferation. Applying a regression model on standard RNA-sequencing data for novel APA events, we identified at least 1,450 genes with shortened 3' UTRs after CFIm25 knockdown, representing 11% of significantly expressed mRNAs in human cells. Marked increases in the expression of several known oncogenes, including cyclin D1, are observed as a consequence of CFIm25 depletion. Importantly, we identified a subset of CFIm25-regulated APA genes with shortened 3' UTRs in glioblastoma tumours that have reduced CFIm25 expression. Downregulation of CFIm25 expression in glioblastoma cells enhances their tumorigenic properties and increases tumour size, whereas CFIm25 overexpression reduces these properties and inhibits tumour growth. These findings identify a pivotal role of CFIm25 in governing APA and reveal a previously unknown connection between CFIm25 and glioblastoma tumorigenicity.

Show MeSH
Related in: MedlinePlus