ABSTRACT
OBJECTIVES AND BACKGROUND: In head and neck cancer including hypopharyngeal carcinoma, cisplatin and 5-fluorouracil usually have been used as neoadjuvant chemotherapeutic agents. We investigated the difference in the influences of cisplatin and 5-fluorouracil (5-FU) on the p53 protein expression and cell responses (cell cycle arrest and apoptosis) in the hypopharyngeal cell line (PHUH-12). METHOD: PNUH-12 with a mutant type p53 (one point mutation at the 78th base, C to G, in exon 7) was treated with cisplatin and 5-FU. Changes in the cell line were assessed by MTT assay, Western blotting (p53 and p21 protein), DNA fragmentation, PI stain, and DNA flow cytometry. RESULTS: The p53 protein expression was increased after the treatment with cisplatin and 5-FU. The expression of p21 protein was increased after the treatment with 5-FU, not cisplatin. With cisplatin, we observed apoptosis by DNA fragmentation and PI stain and the increased S phase on DNA flow cytometry. But, with 5-FU, we couldn't observe apoptosis by DNA fragmentation, PI, and flow cytometry and only the increased G1 phase on DNA flow cytometry. CONCLUSION: In hypopharyngeal cell line (PNUH-12), cisplatin induced p53 dependent apoptosis and 5-FU induced p53 and p21 dependent G0/G1 cell cycle arrest, but not apoptosis.