Expression of the Low Molecular Weight Cyclin E is Early Event in Colorectal Carcinogenesis.

Abstract

Cyclin E is essential for the transition from the G1 to S-phase of the cell cycle, and plays important roles in carcinogenesis in many cancers. Especially, low molecular weight cyclin E is overexpressed in breast cancer and its level of expression correlates well with the progression and prognosis. Although the cyclin E level is amplified, and overexpressed, in many cancers, including colorectal cancer, the role of low molecular weight cyclin E in colorectal cancer remains to be studied. Therefore, the expression of low molecular weight cyclin E in various stages of colorectal tumors was studied. The expression of low molecular weight cyclin E was analyzed in 45 tumors, and compared with paired normal mucosa from the same patients (6 adenomas, 11 stage A, 14 stage B and 14 stage C colorectal cancers) by Western blot analysis. The expres sion of low molecular weight cyclin E was also analyzed in normal colon mucosa from 12 healthy normal controls. The low molecular weight cyclin E was expressed exclusively in all stages of colon tumors, but not in the normal mucosa from the same patients or in the normal controls. However, there was no correlation between tumor progression and the degree of expression of low molecular weight cyclin E. The expression of low molecular weight cyclin E is suggested to be an early event in colorectal carcinogenesis.