PSMA5 Promotes The Tumorigenic Process Of Prostate Cancer And Is Related To Bortezomib Resistance

ObjectiveProstate cancer?PCa?is one of the most common urogenital tumors in men around the world,and its morbidity and mortality are increasing.Previous studies have found that the ubiquitin-proteasome pathway plays an important role in tumors.In this paper,we explored the mechanism of 26s proteasome?5 subunit?PSMA5?and proteasome inhibitor in the carcinogenesis and development of PCa by bioinformatics and related experimental studies,aiming to provide scientific basis for effective targeted diagnosis and treatment of PCa and related drug combination therapy.Methods1.We analyzed the PSMA5 by bioinformatics.First,the mRNA expression levels of PSMA5 gene in the normal and PCa tissues were analyzed by TCGA database.Second,we used the cBioportal website to test the expression of PSMA5 with different Gleason scores and in lymph node metastatic PCa.The last,the relationship between PSMA5 expression and the clinical prognosis of patients with PCa was predicted by GEPIA website,aiming to provide a basis for clinical trial research.2.We used immunohistochemical staining?IHC?and protein imprinting?western blot?to examine PSMA5 expression in PCa and benign prostatic hyperplasia.Furthermore,Western blot and RT-qPCR were used to detect the PSMA5 expression in PCa cell lines?PC3,LnCap,DU145,C4-2?and normal prostatic epithelial cell?RWPE-1?.3.We inhibited PSMA5 expression in PCa cell lines and the changes of epigenetic behavior of PCa cells were observed compared with the control group.The corresponding epigenetics included cell proliferation,migration and invasion ability and percentages of apoptosis.4.PC3 cells were treated with a proteasome inhibitor?bortezomib?,and the IC₅₀concentration of bortezomib was measured by drug concentration gradient method.We then examined the proliferation and apoptosis of PC3 compared between the treatment of bortezomib,PSMA5 inhibition alone or combination.5.The cell line?PC3-R?resistant to bortezomib was cultured by long-term stimulation of bortezomib on PC3 cells,and the expression of PSMA5 was detected in the resistant cell line.The recovery of bortezomib's sensitivity was observed after inhibiting PSMA5 expression in PC3-R cells.Results1.TCGA database analysis showed that PSMA5 expression was significantly upregulated in PCa tissues compared with normal prostate tissues?P<0.001?.Whilst PSMA5 expression was also significantly correlated with the Gleason score of PCa?P=0.027?and lymph node metastasis PCa?P<0.001?.For clinical prognosis,the expression of PSMA5 was significantly related with disease free survival?P=0.048?,but not with overall survival?P>0.05?.2.The results of immunohistochemistry and western blot showed that PSMA5expression in PCa was higher than that in benign prostatic hyperplasia?P<0.05?.The expression of PSMA5 in PCa cells was significantly higher than that in normal prostatic epithelial cells?P<0.05?,and the expression was the highest in PC3 and C4-2 cells.3.It was observed that the proliferation,migration and invasion ability of PC3,C4-2 was significantly weaken and apoptosis percentage increased after PSMA5inhibition,Meanwhile,the epithelial-mesenchymal transition?EMT?ability was decreased.4.Compared with the treatment of bortezomib,PSMA5 inhibition alone,Bortezomib combined with PSMA5 silencing significantly inhibited the proliferation and increase the apoptosis of PC3 cells.5.The expression of PSMA5 was increased in bortezomib resistant cells and cells resistant to bortezomib resumed sensitivity to bortezomib after knocking down PSMA5.ConclusionsPSMA5 expression was correlated with clinical tumor grade and prognosis.The progression of PCa was weaken after PSMA5 inhibition.Meanwhile,PSMA5 and bortezomib can act synergistically in the treatment of PCa and plays an important role in the mechanism of bortezomib resistance.Therefore,PSMA5 can be used as an important therapeutic target to control the progression of prostate cancer in the future.