Published in Cancer Detection and Prevention 2001; 25(5):414-419.

Reduced Expression of p16 and p27 Proteins in Nasopharyngeal Carcinoma

Yuh Baba, MD, PhD,a Mamoru Tsukuda, MD, PhD,a Izumi Mochimatsu, MD,PhD,a Shigeru Furukawa, MD, PhD,a Hiroko Kagata, MD,a Shinri Koshika,DDS, PhD,b Yukio Nakatani, MD, PhD,c Masamichi Hara, MD, PhD,c Yasumasa Kato, PhD,a,b and Yoji Nagashima, MD, PhDc

Departments of aOtolaryngology and cpathology, Yokohama City University School of Medicine, Yokohama, and bDepartment of Biochemistry and Molecular Biology, Kanagawa Dental College, Yokosuka, Japan

Address all correspondence and reprint requests to Yuh Baba, MD. PhD. Department of Otolaryngology. Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa-ku. Yokohama 236-0004, Japan.

ABSTRACT Nasopharyngeal carcinoma (NPC) is a malignant tumor with a high incidence in east Asian countries. Inactivation of cyclin-dependent kinase (CDK) inhibitors (CKIs) and overexpression of G1 cyclin has been thought to be important for tumor development. To determine whether reduction of CKI (p16 and p27) expression was associated with NPC development, we performed immunohistochemical staining of NPC specimens from 20 patients. We found that p16 and p27 proteins were negative in 8 of 20 and 16 of 20 cases, respectively; that either p16 or p27 proteins were negative in 17 of 20; and that both p16 and p27 were negative in 7 of 20. Excepting the cases in which both CKIs were negative, negativity of p27 alone was statistically higher than that of p16 (9/20 versus 1/20, P = .022), suggesting that the reduction of p27 protein is an important event for the multi-step process of NPC development.

KEY WORDS: p27, p16, nasopharyngeal carcinoma.