Identification of a genetic interaction between the tumor suppressor EAF2 and the retinoblastoma protein (Rb) signaling pathway in C. elegans and prostate cancer cells

Abstract

The tumor suppressor EAF2 is regulated by androgen signaling and associated with prostate cancer. While EAF2 and its partner ELL have been shown to be members of protein complexes involved in RNA polymerase II transcriptional elongation, the biologic roles for EAF2 especially with regards to the development of cancer remains poorly understood. We have previously identified the eaf-1 gene in C. elegans as the ortholog of EAF2, and shown that eaf-1 interacts with the ELL ortholog ell-1 to control development and fertility in worms. To identify genetic pathways that interact with eaf-1, we screened RNAi libraries consisting of transcription factors, phosphatases, and chromatin-modifying factors to identify genes which enhance the effects of eaf-1(tm3976) on fertility. From this screen, we identified lin-53, hmg-1.2, pha-4, ruvb-2 and set-6 as hits. LIN-53 is the C. elegans ortholog of human retinoblastoma binding protein 4/7 (RBBP 4/7), which binds to the retinoblastoma protein and inhibits the Ras signaling pathway. We find that lin-53 showed a synthetic interaction with eaf-1(tm3976) where knockdown of lin-53 in an eaf-1(tm3976) mutant resulted in sterile worms. This phenotype may be due to cell death as the treated worms contain degenerated embryos with increased expression of the ced-1:GFP cell death marker. Further we find that the interaction between eaf-1 and lin-53/RBBP4/7 also exists in vertebrates, which is reflected by the formation of a protein complex between EAF2 and RBBP4/7. Finally, overexpression of either human EAF2 or RBBP4 in LNCaP cells induced the cell death while knockdown of EAF2 in LNCaP enhanced cell proliferation, indicating an important role of EAF2 in controlling the growth and survival of prostate cancer cells. Together these findings identify a novel physical and functional interaction between EAF2 and the Rb pathway.

Concordant developmental expression profiles of orthologues in highly divergent Bilateria

“…In this study we performed a systematic approach to identify bilaterian-438 specific genes. Previous investigations concluded that essentially all impor-439 tant developmental regulators precede the origin of bilaterians, and that 440 rewiring of already existing factors was a hallmark of bilaterian evolution 441 [24,56,23,22,48] and our results enhanced by a second BLAST and phy-442 logeny based control step are in support of this. Future data from non-443 bilaterian species might in fact show that even the 35 groups of orthologues 444 we now identified to be conserved across the three model species but with-445 out credible non-bilaterian orthologues were present before the split from…”

Physical and Functional Interactions between ELL2 and RB in the Suppression of Prostate Cancer Cell Proliferation, Migration, and Invasion

“…EAF2 was also shown to act as a tumor suppressor in the murine prostate [17] . More recently, we identified genetic interactions between the EAF2 ortholog in C. elegan s and the retinoblastoma protein (RB) signaling pathway [20] . Thus, ELL2 may also suppress prostate cancer and interact with RB signaling.…”

Graded Proteasome Dysfunction in Caenorhabditis elegans Activates an Adaptive Response Involving the Conserved SKN-1 and ELT-2 Transcription Factors and the Autophagy-Lysosome Pathway

“…2 :: GFP; rol-6 (su1006)] ) [ 54 ], DA2123 ( adIs2122 [lgg-1p :: GFP :: lgg-1 + rol-6(su1006)] ) [ 110 ], HZ1688 ( atg-13(bp414) ) [ 88 ], MAH236 ( sqIs13 [lgg-1p :: GFP :: lgg-1 + odr-1p :: RFP] ) [ 86 ], SJ4001 ( zcIs1[aip-1 :: GFP] ) [ 37 ], and VC1369 ( rpn-10(ok1865) ) were obtained from the Caenorhabditis Genetics Center which is funded by NIH Office of Research Infrastructure Programs (P40 OD010440). The rrIs1[elt-2 :: lacZ :: GFP] transgene which expresses nuclear localized GFP in the intestine has been previously described [ 111 ]. The rpn-10(ok1865) mutant was outcrossed against N2 five times, and one resulting outcrossed homozygous line was used for all subsequent crosses and experiments.…”