Expression of p27 is associated with Bax expression and spontaneous apoptosis in oral and oropharyngeal carcinoma

✍ Scribed by Shigeharu Fujieda; Manabu Inuzuka; Nobuyuki Tanaka; Hiroshi Sunaga; Guo-Kang Fan; Toshihisa Ito; Chizuru Sugimoto; Hideaki Tsuzuki; Hitoshi Saito

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: French
• Weight: 192 KB
• Volume: 84
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/(sici)1097-0215(19990621)84:3<315::aid-ijc20>3.0.co;2-u

✦ Synopsis

p27 Kip1 , a cyclin-dependent kinase inhibitor, is a negative regulator of the cell cycle, and apoptosis is a genetically encoded program of cell death. To clarify the relationship between the cell cycle and apoptosis, we investigated expression of p27, cyclin D1 and apoptosis-related proteins (p53, Bax, Bcl-2 and c-Myc) in 60 cases of oral and oropharyngeal squamous-cell carcinoma (SCC) using an immuno-histochemical approach, and evaluated spontaneous apoptosis in vivo. Our most notable finding was that spontaneous apoptosis in the p27-positive group was significantly higher than that in the p27-negative group (p ‫؍‬ 0.028). In addition, the percentage of p27-positive cells was clearly correlated with that of Bax-positive cells (␥ ‫؍‬ 0.288, p ‫؍‬ 0.028) and with that of cyclin D1-positive cells (␥ ‫؍‬ 0.416, p ‫؍‬ 0.002). Expression of p27 was inversely associated with the clinical stage of total tumor progression (p ‫؍‬ 0.027). However, no correlation was found between p27 expression and the following parameters: gender, tumor size, lymph node metastasis, overall survival and disease-free survival. Our results give evidence that the action of the cell-cycle regulator p27 is closely linked with apoptosis in clinical samples from patients and indicate that over-expression of p27 might induce apoptosis in cancer cells through elevation of Bax expression, thereby acting on tumor progression.