We examined the susceptibility of five human bone and soft tissue sarcoma cell lines to transfection with recombinant p53 adenovirus vector (AxCA-p53). Transfection efficiency was more than 90% at 72 h with AxCA-lacZ at a multiplicity of infection (MOI) of 50 in all the cell lines, except for MG-63 (p53 gene mutated) cells. Western blot analysis showed overexpression of both P21/Waf1 and Bax protein in all the cell lines, implying sufficient and successful p53 gene transfection. AxCA-p53 transfection at MOI of 50 resulted in a significant decline of viable cells at 72 h, due to apoptosis, in NY (mutated) and Saos-2 (deletion), but not in the other three lines. The two apoptosis-induced cell lines showed a gradual increase in Bax expression up to 72 h and non-detectable expression of Bcl-XL from 48 h, suggesting the involvement of an apoptosis-inducing mechanism. Pre-treatment with cis-diamminedichloroplatinum (II) (CDDP) at 0.1 μg/ml significantly suppressed tumor cell viability in NY and HuO-3N1 (mutated), but not in the other three lines including HT-1080 carrying the wild-type p53 gene, implying the existence of different mechanisms for the tumor suppressive effect of p53 gene transfection and CDDP. These results indicate that wild-type p53 gene transfection with CDDP is a promising therapy for some, but not all, non-resectable bone-and soft tissue sarcomas, regardless of intrinsic p53 gene status.

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