5-Aza-2'-Deoxycytidine and CDDP Synergistically Induce Apoptosis in Renal Carcinoma Cells via Enhancing the APAF-1 Activity

Abstract

Background: It has been reported that the hypermethylation of APAF-1, DAPK-1 and other tumor suppressive genes (TSGs) correlates with progression of renal cell carcinoma and exerts prognostic and diagnostic relevance in renal cell carcinoma. A recent study has confirmed that demethylation regulates the TSGs expression and proliferation of various types of cancer cells. The present study was to recognize a potential anti-tumor effect of 5-aza-2'-deoxycytidine (DAC), a demethylation agent.

Methods: We evaluated the DNA demethylation by DAC in human renal carcinoma cells and determined the synergism of the demethylation with the toxicity of Cisplatin (CDDP), which is a commonly utilized anti-tumor agent for renal carcinoma.

Results: It was demonstrated that DAC promoted a significant global genomic demethylation and improved APAF-1 expression at both mRNA and protein levels. The DAC treatment deteriorated the CDDP-induced viability decreasing Caki or ACHN cells and synergized the apoptosis induction of CDDP in ACHN cells. The treatment with both DAC and CDDP promoted a significantly higher level of renal carcinoma cell apoptosis than singular DAC or CDDP treatment. The APAF-1 knockdown significantly inhibited the synergism of DAC with the CDDP-induced apoptosis in ACHN cells.

Conclusions: The present study confirmed that DAC demethylated the CpGs, particularly APAF-1 in renal carcinoma cells, and that the demethylation synergized the cytotoxity of CDDP in renal carcinoma cells via enhancing the CDDP-induced apoptosis.