Cyclin D1, Retinoblastoma and p16 Protein Expression in Carcinoma of the Gallbladder

Background: Cancer of the gallbladder is a relatively rare neoplasm with a poor prognosis. The exactmechanisms of its genesis are not known and very little information is available on molecular events leading tolabeling this as an orphan cancer. Materials and
Methods: In this prospective case control study we evaluatedthe expression of p16, pRb and cyclin D1 by immunohistochemistry to study the G1-S cell-cycle check point andits possible role in gallbladder carcinogenesis. A total of 25 patients with gallbladder carcinoma (group I), 25with cholelithiasis (group II) and 10 normal controls. were enrolled
Results: Cyclin D1 expression was seen in10 (40%) patients each with carcinoma and cholelithiasis while only in 2 (20%) of the normal gallbladders butdifferences were not statistically significant (p value=0.488). p16 was expressed in 12% patients of carcinoma ofthe gallbladder and 28% of cholelithiasis, however this difference was not statistically significant (p value=0.095).Retinoblastoma protein was found to be expressed in 50% of normal gallbladders and 6 (24%) of carcinomaand 8 (32%) of gallstones. The present study failed to demonstrate any conclusive role of cyclin D1/RB/ p16pathway in carcinoma of the gallbladder.
Conclusions: The positive relation observed between tumor metastasisand cyclinD1 expression and p16 with nodal metastasis suggested that higher cyclin D1/p16 expression may actas a predictive biomarker for aggressive behavior of gallbladder malignancies.