Exogenous p53 and ASPP2 expression enhances rAdV-TK/GCV-induced death in hepatocellular carcinoma cells lacking functional p53

Abstract

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.

“Non-Essential” Proteins of HSV-1 with Essential Roles In Vivo: A Comprehensive Review

“…It was observed in breast cancer cells that the HSV-TK/GCV system induced p53-dependent DNA damage responses and cell cycle arrest, perturbing mitochondrial homeostasis through membrane potential dysfunction and release of cytochrome c into the cytoplasm in neuroblastoma cells [ 519 , 525 , 526 ]. Similar findings were reported in hepatocellular carcinoma cells using an adenovirus method of delivery for HSV-TK [ 527 ]. The HSV-TK/GCV system has also been seen to be effective in tumor models in mice [ 528 , 529 , 530 , 531 ].…”

Connexin 43 SUMOylation improves gap junction functions between liver cancer stem cells and enhances their sensitivity to HSVtk/GCV

“…The main obstacle is that these cancer stem cells are often in a state of dormancy which impairs the treatment effects of chemotherapeutic drugs (9). Some recent studies have shown that the herpes simplex virus thymidine kinase (HSVtk) gene and the complementary treatment with ganciclovir (GCV) exert marked antitumor effects against HCC by promoting apoptosis and inhibiting angiogenesis (10,11). However, it is still difficult to prevent the recurrence of liver tumors (10)(11)(12).…”

Ultrasound‐guided intertumoral injection of contrast agents combined with human p53 gene for the treatment of breast cancer

“…A study by Liu et al. further confirmed that exogenous p53 plays an important role in improving cell death in hepatocellular carcinomas (HCC), therefore enhancing therapeutic effects in HCC patients who lack normal p53 functions [32].…”

“…Honda and his colleagues reported that the transcriptional effects of exogenous p53 gene could be promoted by an upstream estrogen response, leading to lower transfection rates by inhibiting the cell cycle [31]. A study by Liu et al further confirmed that exogenous p53 plays an important role in improving cell death in hepatocellular carcinomas (HCC), therefore enhancing therapeutic effects in HCC patients who lack normal p53 functions [32].…”