Identification of novel TMPRSS2:ERG mechanisms in prostate cancer metastasis: involvement of MMP9 and PLXNA2

International audienceProstate cancer (PCa) is one of the major public health problems in Western countries. Recently, the TMPRSS2:ERG gene fusion, which results in the aberrant expression of the transcription factor ERG, has been shown to be the most common gene rearrangement in PCa. Previous studies have determined the contributions of this fusion in PCa disease initiation and/or progression in vitro and in vivo. In this study on TMPRSS2:ERG regulation in PCa, we used an androgen receptor and TMPRSS2:ERG fusion double-negative PCa cell model: PC3c. In three cell clones with different TMPRSS2:ERG expression levels, ectopic expression of the fusion resulted in significant induction of cell migration and invasion in a dose-dependent manner. In agreement with this phenotype, high-throughput microarray analysis revealed that a set of genes, functionally associated with cell motility and invasiveness, were deregulated in a dose-dependent manner in TMPRSS2:ERG-expressing cells. Importantly, we identified increased MMP9 (Metalloproteinase 9) and PLXNA2 (Plexin A2) expression in TMPRSS2:ERG-positive PCa samples, and their expression levels were significantly correlated with ERG expression in a PCa cohort. In line with these findings, there was evidence that TMPRSS2:ERG directly and positively regulates MMP9 and PLXNA2 expression in PC3c cells. Moreover, PLXNA2 upregulation contributed to TMPRSS2:ERG-mediated enhancements of PC3c cell migration and invasion. Furthermore, and importantly, PLXNA2 expression was upregulated in metastatic PCa tumors compared with localized primary PCa tumors. This study provides novel insights into the role of the TMPRSS2:ERG fusion in PCa metastasis

YK-4-279 Inhibits ERG and ETV1 Mediated Prostate Cancer Cell Invasion

Background: Genomic rearrangements involving the ETS family of transcription factors occur in 40–70 % of prostate cancer cases. ERG and ETV1 are the most common ETS members observed in these genetic alterations. The high prevalence of these rearrangements and their biological significance represents a novel therapeutic target for the treatment of prostate cancer. Methods and Findings: We recently reported the development of YK-4-279, a small molecule inhibitor of EWS-FLI1 oncoprotein in Ewing’s Sarcoma. Since ERG and ETV1 belong to the same class of ETS factors as FLI1, we tested the ability of YK-4-279 to inhibit biological functions of ERG and ETV1 proteins in prostate cancer. YK-4-279 inhibited ERG and ETV1 mediated transcriptional activity in a luciferase assay. YK-4-279 also decreased ERG and ETV1 downstream target mRNA and protein expression in ETV1-fusion positive LNCaP and ERG fusion positive VCaP cells. YK-4-279 reduced the motility of LNCaP cells in a scratch assay and the invasive phenotype of both LNCaP and VCaP cells in a HUVEC invasion assay. Fusion-negative PC3 cells were unresponsive to YK-4-279. SiRNA mediated ERG knockdown in VCaP cells resulted in a loss of drug responsiveness. Concurrently, transient ERG expression in PC-3 cells resulted in increased invasive potential, which was reduced by YK-4-279. Conclusion: These data demonstrate that YK-4-279 inhibits ERG and ETV1 biological activity in fusion-positive prostat

Unique multifunctional HSD17B4 gene product: 17ß-hydroxysteroid dehydrogenase 4 and D-3- hydroxyacryl-coenzyme A dehydrogenase/hydratase involved in Zellweger syndrome.

Six types of human 17β-hydroxysteroid dehydrogenases catalyzing the conversion of estrogens and androgens at position C17 have been identified so far. The peroxisomal 17β-hydroxysteroid dehydrogenase type 4 (17β-HSD 4, gene name HSD17B4) catalyzes the oxidation of estradiol with high preference over the reduction of estrone. The highest levels of 17β-HSD 4 mRNA transcription and specific activity are found in liver and kidney followed by ovary and testes. A 3 kb mRNA codes for an 80 kDa (737 amino acids) protein featuring domains which are not present in the other 17β-HSDs. The N- terminal domain of 17β-HSD 4 reveals only 25% amino acid similarity with the other types of 17β-HSDs. The 80 kDa protein is N-terminally cleaved to a 32 kDa enzymatically active fragment. Both the 80 kDa and the N-terminal 32 kDa (amino acids 1-323) protein are able to perform the dehydrogenase reaction not only with steroids at the C17 position but also with D-3-hydroxyacyl- coenzyme A (CoA). The enzyme is not active with L-stereoisomers. The central part of the 80 kDa protein (amino acids 324-596) catalyzes the 2-enoyl-acyl- CoA hydratase reaction with high efficiency. The C-terminal part of the 80 kDa protein (amino acids 597-737) facilitates the transfer of 7- dehydrocholesterol and phosphatidyl-choline between membranes in vitro. The HSD17B4 gene is stimulated by progesterone, and ligands of PPARα (peroxisomal proliferator activated receptor alpha) such as clofibrate, and is down-regulated by phorbol esters. Mutations in the HSD17B4 lead to a fatal form of Zellweger syndrome.SCOPUS: re.jinfo:eu-repo/semantics/publishe

Viral oncoproteins target the DNA methyltransferases

International audienceSmall DNA tumour viruses have evolved a number of mechanisms to drive nondividing cells into S phase. Virally encoded oncoproteins such as adenovirus E1A and human papillomavirus (HPV) E7 can bind an array of cellular proteins to override proliferation arrest. The DNA methyltransferase Dnmt1 is the major mammalian enzyme responsible for maintaining CpG methylation patterns in the cell following replication. One of the hallmarks of tumour cells is disrupted DNA methylation patterns, highlighting the importance of the proper regulation of DNA methyltransferases in normal cell proliferation. Here, we show that adenovirus 5 E1A and HPV-16 E7 associate in vitro and in vivo with the DNA methyltransferase Dnmt1. Consistent with this interaction, we find that E1A and E7 can purify DNA methyltransferase activity from nuclear extracts. These associations are direct and mediated by the extreme N-terminus of E1A and the CR3 zinc-finger domain of E7. Furthermore, we find that a point mutant at leucine 20 of E1A, a residue known to be critical for its transformation functions, is unable to bind Dnmt1 and DNA methyltransferase activity. Finally, both E1A and E7 can stimulate the methyltransferase activity of Dnmt1 in vitro. Our results provide the first indication that viral oncoproteins bind and regulate Dnmt1 enzymatic activity. These observations open up the possibility that this association may be used to control cellular proliferation pathways and suggest a new mechanism by which small DNA tumour viruses can steer cells through the cell cycle