Yang Min, Cao Xin, Yu Ming Can, Gu Jin Fa, Shen Zong Hou, Ding Miao, Yu De Bing, Zheng Shu, Liu Xin yuan
Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Hum Gene Ther. 2008 Apr;19(4):343-53. doi: 10.1089/hum.2007.0137.
ST13 is a cofactor of heat shock protein 70 (Hsp70). To date, all data since the discovery of ST13 in 1993 until more recent studies in 2007 have proved that ST13 is downregulated in tumors and it was proposed to be a tumor suppressor gene, but no work reported its antitumor effect and apoptotic mechanism. In the work described in this paper, ST13 was inserted into ZD55, an oncolytic adenovirus with the E1B 55-kDa gene deleted, to form ZD55-ST13, which exerts an excellent antitumor effect in vitro and in an animal model of colorectal carcinoma SW620 xenograft. ZD55-ST13 inhibited tumor cells 100-fold more than Ad-ST13 and ZD55-EGFP in vitro. However, ZD55-ST13 showed no damage of normal fibroblast MRC5 cells. In exploring the mechanism of ZD55-ST13 in tumor cell killing, we found that ZD55-ST13-infected SW620 cells formed apoptotic bodies and presented obvious apoptosis phenomena. ZD55-ST13 induced the upregulation of Hsp70, the downregulation of antiapoptotic gene Bcl-2, and the release of cytochrome c. Cytochrome c triggered apoptosis by activating caspase-9 and caspase-3, which cleave the enzyme poly(ADP-ribose) polymerase in ZD55-ST13-infected SW620 cells. In summary, overexpressed ST13 as mediated by oncolytic adenovirus could exert potent antitumor activity via the intrinsic apoptotic pathway and has the potential to become a novel therapeutic for colorectal cancer gene therapy.
ST13是热休克蛋白70（Hsp70）的一种辅助因子。迄今为止，自1993年发现ST13至2007年的最新研究，所有数据均证明ST13在肿瘤中表达下调，并且它被认为是一种肿瘤抑制基因，但尚无研究报道其抗肿瘤作用及凋亡机制。在本文所述的研究中，将ST13插入ZD55（一种缺失E1B 55-kDa基因的溶瘤腺病毒）中，构建成ZD55-ST13，其在体外和结直肠癌SW620异种移植动物模型中均发挥出优异的抗肿瘤作用。在体外，ZD55-ST13抑制肿瘤细胞的能力比Ad-ST13和ZD55-EGFP强100倍。然而，ZD55-ST13对正常成纤维细胞MRC5无损伤作用。在探究ZD55-ST13杀伤肿瘤细胞的机制时，我们发现ZD55-ST13感染的SW620细胞形成凋亡小体并呈现明显的凋亡现象。ZD55-ST13可诱导Hsp70上调、抗凋亡基因Bcl-2下调以及细胞色素c释放。细胞色素c通过激活caspase-9和caspase-3触发凋亡，这两种酶可切割ZD55-ST13感染的SW620细胞中的聚（ADP-核糖）聚合酶。综上所述，溶瘤腺病毒介导的ST13过表达可通过内源性凋亡途径发挥强大的抗肿瘤活性，具有成为结直肠癌基因治疗新方法的潜力。
