Evaluation of the chemosensitivity of head and neck cancer cells based on the diverse function of mutated-p53.

Pre-therapeutic evaluation of p53 gene is very important for treating patients with head and neck cancer. However, the analysis for p53 gene has generally been done by immunohistochemistry, polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) and direct sequencing. Functional analysis system for p53 transcriptional activity in mammalian cells is now required. We developed a functional analysis system for p53 transcriptional activity in cancer cells. We used two human head and neck cancer cell lines harboring mutated p53 gene, HSG (Asn30Ser) and TYS (Asp281His), and a human osteosarcoma cell line, Saos-2 as a control. We transfected these cells with luciferase reporter plasmids containing promoter sequence of p53 target genes (p21waf1, BAX, MDM2, p53AIP1 or PUMA). After treating the cells with chemotherapeutic drugs, alteration of the luciferase activity was measured. In HSG cells, none of the target gene promoters was activated by treatment with chemotherapeutic drugs. In TYS cells, p21waf1 promoter was markedly activated by treatment with chemotherapeutic drugs, but Bax and p53AIP1 promoter was not activated. This type of mutated-p53 in TYS cells prevents cell death from DNA damage, and probably accumulates genetic alterations and accelerates the malignant progression of the cells by DNA damaging therapy. Thus, analysis for the diverse function of mutated-p53 may help to determine the therapeutic strategy, especially for chemotherapy and radiation in the individual patients with head and neck cancer.