The homologous ETV1, ETV4 and ETV5 proteins form the PEA3 subfamily of ETS transcription factors. In Ewing tumors, chromosomal translocations affecting ETV1 or ETV4 are an underlying cause of carcinogenesis. Likewise, chromosomal rearrangements of the ETV1, ETV4 or ETV5 gene occur in prostate tumors and are thought to be one of the major driving forces in the genesis of prostate cancer. In addition, these three ETS proteins are implicated in melanomas, breast and other types of cancer. Complex posttranslational modifications govern the activity of PEA3 factors, which can promote cell proliferation, motility and invasion. Here, we review evidence for a role of ETV1, 4 and 5 as oncoproteins and describe modes of their action. Modulation of their activation or interaction with cofactors as well as inhibiting crucial target gene products may ultimately be exploited to treat various cancers that are dependent on the PEA3 group of ETS transcription factors.
The homologous proteins p68 and p72 are members of the DEAD box family of RNA helicases. Here, we show that expression of both of these helicases strongly increases during the polyp!adenoma!adenocarcinoma transition in the colon. Furthermore, p68 and p72 form complexes with Bcatenin and promote the ability of B-catenin to activate gene transcription. Conversely, simultaneous knockdown of p68 and p72 leads to reduced expression of the B-cateninregulated genes, c-Myc, cyclin D1, c-jun, and fra-1, all of which are proto-oncogenes. Moreover, transcription of the cell cycle inhibitor p21 WAF1/CIP1 , whose expression is suppressed by c-Myc, is enhanced on p68/p72 knockdown. Thus, p68/p72 may contribute to colon cancer formation by directly upregulating proto-oncogenes and indirectly by down-regulating the growth suppressor p21 WAF1/CIP1 . Accordingly, knockdown of p68 and p72 in colon cancer cells inhibits their proliferation and diminishes their ability to form tumors in vivo . Altogether, these results suggest that p68/p72 overexpression is not only a potential marker of colon cancer but is also causally linked to this disease. Therefore, p68 and p72 may be novel targets in the combat against colon cancer. [Cancer Res 2007;67(16):7572-8]
Histone demethylase upregulation has been observed in human cancers, yet it is unknown whether this is a bystander event or a driver of tumorigenesis. We found that overexpression of lysine-specific demethylase 4A (KDM4A, also known as JMJD2A) was positively correlated with Gleason score and metastasis in human prostate tumors. Overexpression of JMJD2A resulted in the development of prostatic intraepithelial neoplasia in mice, demonstrating that JMJD2A can initiate prostate cancer development. Moreover, combined overexpression of JMJD2A and the ETS transcription factor ETV1, a JMJD2A-binding protein, resulted in prostate carcinoma formation in mice haplodeficient for the phosphatase and tensin homolog (Pten) tumor-suppressor gene. Additionally, JMJD2A cooperated with ETV1 to increase expression of yes associated protein 1 (YAP1), a Hippo pathway component that itself was associated with prostate tumor aggressiveness. ETV1 facilitated the recruitment of JMJD2A to the YAP1 promoter, leading to changes in histone lysine methylation in a human prostate cancer cell line. Further, YAP1 expression largely rescued the growth inhibitory effects of JMJD2A depletion in prostate cancer cells, indicating that YAP1 is a downstream effector of JMJD2A. Taken together, these data reveal a JMJD2A/ETV1/YAP1 axis that promotes prostate cancer initiation and that may be a suitable target for therapeutic inhibition.
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