The p53-induced Siva-1 plays a significant role in cisplatin-mediated apoptosis

Posted by Article Type, Issue, Original Article, Vol 8, Issue 1Posted on

John L Barkinge1, Radhika Gudi1, Hawkins Sarah1, Fei Chu2, Alip Borthakur3, Bellur S Prabhakar1, Kanteti V.S Prasad1
1 Department of Microbiology and Immunology, University of Illinois at Chicago, 835 S. Wolcott Ave., MC 790, Chicago, IL 60612, USA
2 Department of Microbiology and Immunology, Children’s Memorial Hospital, Northwestern University, Chicago, IL, 60614, USA
3 Department of Medicine, University of Illinois at Chicago, 60612, USA
DOI: 10.4103/1477-3163.45389

ABSTRACT

Background: The pro-apoptotic protein Siva-1 functions in both extrinsic and intrinsic cell death signaling; however, the exact contribution of the endogenous Siva-1 to DNA damage-induced apoptosis is unclear. Using cisplatin, a chemotherapeutic drug, to induce DNA damage and cell death, we determined the role of Siva-1. Methods: Cisplatin treated HCT116 colorectal carcinoma cells (p53+/+ and -/-) were used in the study. With the help of recombinant lentivirus that can express siSiva (siRNA that specifically targets Siva-1), we also generated Siva-1 knockdown HCT116 cells. Apoptosis was determined by tetramethyl rhodamine methyl ester (TMRM) staining and propidium iodide (PI) staining. Results: Treatment with cisplatin induced Siva-1 expression in a p53 dependent manner. In Siva-1 knockdown p53+/+ HCT116 colorectal carcinoma cells, loss of Siva-1 expression conferred significant resistance to cisplatin-induced apoptosis. Although Siva-1 levels were positively regulated by p53, Siva-1-induced apoptosis did not require p53. Despite the fact that Siva-1 lacks even a minimal BH3 domain, similar to other proapoptotic Bcl2 family members induced by p53, we showed that Siva-1 mediated apoptosis is characterized by Bax oligomerization and cytochrome c leakage from mitochondria. The putative amphipathic helical region in Siva-1 (SAH) appeared to function analogously to a BH3 domain. Conclusion: The p53 induced Siva-1 is one of the effector molecules, which plays a significant role in DNA damage-induced cell death.

Keywords: Apoptosis, Bcl-2 family, cisplatin, cytochrome c, p53, Siva-1