EXPRESSION OF P16(INK4) AND RETINOBLASTOMA PROTEIN RB IN VULVAR LESIONS OF CHINESE WOMEN

The protein products of the two tumor suppressor genes located on 9p a nd 13p, p16(INK4) and Rb, respectively, play an important role in regu lation of the cell cycle and are implicated in tumorigenesis. We exami ned 49 cases of benign vulvar lesions, vulvar intraepithelial neoplasi a (VIN), and squamous cell carcinoma with immunohistochemical staining to determine expression of p16(INK4) and Rb. All and 86% of benign le sions expressed Rb and p16(INK4) respectively; 40% each of VIN I and V IN III expressed p16(INK4) and Rb, respectively; and 37 and 68% of squ amous cell carcinomas expressed p16(INK4) and Rb, respectively. The co mbination of the lack of p16(INK4) and/or Rb expression increased from benign lesions (14.3%), through VIN I (60%) and VIN III (60%), to inv asive squamous cell carcinoma (72%), thus supporting the postulation t hat alterations in p16(INK4) Or Rb could be significant events in prog ression of disease. The loss of Rb expression also increased from stag e I carcinoma (16.7%) through stage II (26.7%) and III (44.4%), to IV (50%), suggesting that Rb may play an important role in tumor progress ion. A larger study on VIN lesions and genetic coding is suggested to further investigate the role of p16(INK4) Rb, and other factors in tum origenesis and progression of vulvar cancers. (C) 1998 Academic Press.