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World J Gastroenterol. Oct 21, 2006; 12(39): 6391-6396
Published online Oct 21, 2006. doi: 10.3748/wjg.v12.i39.6391
Aberrant cytological localization of p16 and CDK4 in colorectal epithelia in the normal adenoma carcinoma sequence
Po Zhao, Xin Mao, Ian C Talbot
Po Zhao, Department of Pathology, Chinese PLA General Hospital, Beijing 100853, China
Po Zhao, Academic Department of Pathology, St. Mark’s Hospital, Cancer Research UK, Colorectal Cancer Unit, Harrow, HA1 3UJ, London, United Kingdom
Xin Mao, Ian C Talbot, Academic Department of Pathology, St. Mark’s Hospital, Cancer Research UK, Colorectal Cancer Unit, Harrow, HA1 3UJ, London, United Kingdom
Correspondence to: Dr Po Zhao, Department of Pathology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China. zhaopo@plagh.com.cn
Telephone: +86-10-66937736 Fax: +86-10-68181689
Received: May 6, 2006
Revised: May 28, 2006
Accepted: June 14, 2006
Published online: October 21, 2006
Abstract

AIM: To study the correlation between the patterns of subcellular expression of p16 and CDK4 in colorectal epithelia in the normal-adenoma-carcinoma sequence.

METHODS: Paraffin sections of 43 cases of normal colorectal epithelia and corresponding adenomas as well as carcinomas were analysed immunocytochemically for subcellular expression of p16 and CDK4 proteins.

RESULTS: Most carcinomas showed more cytoplasmic overexpression for p16 and CDK4 than the adenomas from which they arised or the adjacent normal mucosa. Most normal or non-neoplastic epithelia showed more p16 and CDK4 expression in the nucleus than their adjacent adenomas and carcinomas. There was a significant difference between the subcellular expression pattern of p16 and CDK4 in normal-adenoma-carcinoma sequence epithelia (P < 0.001). Neither p16 nor CDK4 subcellular patterns correlated with histological grade or Dukes' stage.

CONCLUSION: Interaction of expression of p16 and CDK4 plays an important role in the Rb/p16 pathway. Overexpression of p16 and CDK4 in the cytoplasm, as well as loss expression of p16 in the nucleus might be important in the evolution of colorectal carcinoma from adenoma and, of adenoma from normal epithelia.

Keywords: Colorectal neoplasm; p16; CDK4; Immuno-cytochemistry