We previously identified TDRG1 (testis developmental related gene 1), a novel gene with exclusive expression in testis, promoted the proliferation and progression of cultured human seminoma cells through PI3K/Akt/mTOR signaling. As increasing evidence reveal that aberrant activation of this signaling is involved in cisplatin resistance. Then, in this study, we further explored whether TDRG1 regulated the chemosensitivity of seminoma TCam-2 cells to cisplatin. Our researches showed TDRG1 could regulate the viability of TCam-2 cells following cisplatin treatment in vitro through control of both cell apoptosis and cell cycle. Mechanistically, we observed TDRG1 positively regulated the expression levels of the key elements in PI3K/Akt/mTOR pathway including p-PI3K, p-Akt and p-mTOR and also affected the translocation of nuclear p-Akt in TCam-2 cells during cisplatin treatment. Meanwhile, the levels of Bad, cytochrome c, caspase-9 ratio (activated/total), caspase-3 ratio (activated/total) and cleaved-PARP were negatively modulated by TDRG1, which meant the involvement of mitochondria-mediated apoptotic pathway. Furthermore, we found the effect of TDRG1 knockdown or TDRG1 overexpression could be reversed by IGF-1, a PI3K signaling activator, or LY294002, a inhibitor of this pathway, respectively. Similar effects of TDRG1 on cisplatin chemosensitivity and associated molecular mechanism were also confirmed in vivo by employing xenograft assays. In addition, the positive correlation between TDRG1 and p-PI3K, or p-Akt, was found in tumor tissues from seminoma patients. In conclusion, we uncover that TDRG1 regulates chemosensitivity of TCam-2 cells to cisplatin through PI3K/Akt/mTOR signaling and mitochondria-mediated apoptotic pathway both in vitro and in vivo.
Cancer biology & therapy. 2016 Apr 22 [Epub ahead of print]
Yu Gan, Yong Wang, Zhengyu Tan, Jun Zhou, Riko Kitazawa, Xianzhen Jiang, Yuxin Tang, Jianfu Yang
a Department of Urology , The Third Xiangya Hospital of Central South University , Changsha , People's Republic of China., a Department of Urology , The Third Xiangya Hospital of Central South University , Changsha , People's Republic of China., a Department of Urology , The Third Xiangya Hospital of Central South University , Changsha , People's Republic of China., a Department of Urology , The Third Xiangya Hospital of Central South University , Changsha , People's Republic of China., b Department of Diagnostic Pathology , Ehime University Hospital , Shitsukawa, Tōon , Ehime Perfecture , Japan., a Department of Urology , The Third Xiangya Hospital of Central South University , Changsha , People's Republic of China., a Department of Urology , The Third Xiangya Hospital of Central South University , Changsha , People's Republic of China., a Department of Urology , The Third Xiangya Hospital of Central South University , Changsha , People's Republic of China.