The cancer testis antigen TDRD1 regulates prostate cancer proliferation by associating with the snRNP biogenesis machinery

Abstract

Prostate cancer is the most commonly diagnosed noncutaneous cancer in American men. TDRD1, a germ cell-speci c gene, is erroneously expressed in more than half of prostate tumors, but its role in prostate cancer development remains elusive. In this study, we identi ed a PRMT5-TDRD1 signaling axis that regulates the proliferation of prostate cancer cells. PRMT5 is a protein arginine methyltransferase essential for small nuclear ribonucleoprotein (snRNP) biogenesis. Methylation of Sm proteins by PRMT5 is a critical initiation step for assembling snRNPs in the cytoplasm, and the nal snRNP assembly takes place in Cajal bodies in the nucleus. By mass spectrum analysis, we found that TDRD1 interacts with multiple subunits of the snRNP biogenesis machinery. In the cytoplasm, TDRD1 interacts with methylated Sm proteins in a PRMT5-dependent manner. In the nucleus, TDRD1 interacts with Coilin, the scaffold protein of Cajal bodies. Ablation of TDRD1 in prostate cancer cells disrupted the integrity of Cajal bodies, affected the snRNP biogenesis, and reduced cell proliferation. Taken together, this study represents the rst characterization of TDRD1 functions in prostate cancer development and suggests TDRD1 as a potential therapeutic target for prostate cancer treatment.GCA ATA GT-5') and the non-targeting control vector(U-009501-01-02) were obtained from Dharmacon (CO, USA). The ERG lentiviral sgRNA vector was purchased from Sigma-Aldrich with the sgRNA sequence: 5'-CCG TGG AGA GTT TTG TAA GGC T-3'. VCaP cells were transduced with lentivirus expressing Cas9 and then selected with 5 µg/ml blasticidin (Sigma-Aldrich #15205), followed by transduction with lentiviruses containing TDRD1 and ERG sgRNAs and control, followed by a selection of 5 µg/ml puromycin (Sigma-Aldrich #P8833). Cell growth assayVCaP, 22Rv1, and LNCaP cells were seeded at a density of 1 × 10 4 cells per well in at-bottomed 96-well plates and grew for 3-11 days. CellTiter-Glo® Luminescent Cell Viability Assay (Promega, Madison, WI, USA) was used to measure cell viability every other day, and the luminescence was determined by Synergy™ neo2 multi-mode reader (BioTek, Winooski, VT, USA).