A combination treatment with SAHA and ad-p63/p73 shows an enhanced anticancer effect in HNSCC

Suberoylanilide hydroxamic acid (SAHA) is one of the most widely used histone deacetylase inhibitors. However, the potential advantage of SAHA has not been sufficiently validated as an adjunct to gene therapy of head and neck squamous cell carcinoma (HNSCC). SAHA has been shown to boost the efficiency of gene transfer by upregulating the expression of coxsackie adenoviral receptor on treated cells. The p53 family genes, p63 and p73, have been shown to have characteristics similar to p53, and although they are not confirmed as tumor suppressors, DNA-damaging signals induce their overexpression. We previously reported that the adenovirus-mediated transfer of p63 or p73 showed an effective cancer-killing effect similar to that of p53. In this study, we combined SAHA with adenoviral delivery of p63 or p73 to enhance the efficiency of gene therapy. This combination resulted in a significantly enhanced cancer-killing effect in HNSCC cell lines but had no effect on normal human fibroblasts. SAHA treatment added to ad-p63/p73 gene delivery caused an increase in p21 expression and cleaved poly-ADP ribose polymerase. Our results indicate that adjuvant SAHA treatment could be developed as a therapeutic strategy to enhance the efficiency of adenoviral gene transfer in the treatment of cancer.