Exogenous p53 and ASPP2 expression enhances rAdV-TK/ GCV-induced death in hepatocellular carcinoma cells lacking functional p53
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Xiuhong Liu1,2,*, Shuang Wang1,2,*, Xianghua Guo2, Feili Wei2, Jiming Yin2, Yunjin Zang1, Ning Li1, Dexi Chen1,2
1Beijing You’an Hospital Affiliated with Capital Medical University, Beijing 100069, China
2Beijing Institute of Hepatology, Capital Medical University, Beijing 100069, China
*These authors have contributed equally to this work
Dexi Chen, e-mail: firstname.lastname@example.org
Ning Li, e-mail: email@example.com
Keywords: gene therapy, p53, ASPP2, ganciclovir, hepatocellular carcinoma
Received: May 12, 2015 Accepted: January 13, 2016 Published: February 26, 2016
Suicide gene therapy using herpes simplex virus-1 thymidine kinase (HSV-TK) in combination with ganciclovir (GCV) has emerged as a potential new method for treating cancer. We hypothesize that the efficacy of HSV-TK/GCV therapy is at least partially dependent on p53 status in hepatocellular carcinoma (HCC) patients. Using recombinant adenoviral vectors (rAdV), TK, p53, and ASPP2 were overexpressed individually and in combination in Hep3B (p53 null) and HepG2 (p53 wild-type) cell lines and in primary HCC tumor cells. p53 overexpression induced death in Hep3B cells, but not HepG2 cells. ASPP2 overexpression increased rAdV-TK/GCV-induced HepG2 cell death by interacting with endogenous p53. Similarly, ASPP2 reduced survival in rAdV-TK/GCV-treated primary HCC cells expressing p53 wild-type but not a p53 R249S mutant. Mutated p53 was unable to bind to ASPP2, suggesting that the increase in rAdV-TK/GCV-induced cell death resulting from ASPP2 overexpression was dependent on its interaction with p53. Additionally, γ-H2AX foci, ATM phosphorylation, Bax, and p21 expression increased in rAdV-TK/GCV-treated HepG2 cells as compared to Hep3B cells. This suggests that the combined use of HSV-TK, GCV, rAdV-p53 and rAdV-ASPP2 may improve therapeutic efficacy in HCC patients lacking functional p53.
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