Alterations found in pl6/Rb/cyclin D1 pathway in the dysplastic and malignant cervical epithelium.

Cervical cancer is the one of the most common cancers affecting the south Indian women. The objective of the present study was to analyze the pl6/Rb/cyclin D1 pathway in the normal (n=30), dysplastic (n=56), and malignant cervical epithelium (n=142) using immunohistochemistry. The positive immunoreactivity for p16 was as follows: CIN I--1/12 (8.3%), CIN II--2/8 (25%), CIN III--31/36 (86.1%), and in invasive tumors-121/142 (85.1%); for cyclin D1 it was CIN I--4/12 (66.6%), CIN II--5/8 (62.5%), CIN III--0%, and invasive tumors--5/142 (3.5%); and for pRb it was CIN I--9/12 (75%), CIN II--5/8(62.5%), CIN III--1/36 (97.2%), and in invasive tumors--41/142 (28.8%). Expression of cyclin D1 and p16 in the CINs were mutually exclusive and the correlation between the two biomarkers was found to be statistically significant (p = 0.0009). There was downregulation of pRb in invasive cancers, with only 32% (39/121) of the p16-positive tumors being positive for pRb (p = 0.032). Analysis of the pattern of expression of these biomolecules showed increased p16-positive phenotypes and decreased cyclin D1- and pRB-positive phenotype among the invasive tumors compared to low-grade CIN lesions.