Increased Farnesyltransferase Activity in Human Colorectal Cancer: Relationship with Clinicopathological Features and K-ras Mutation

Abstract

The enzyme farnesyltransferase has emerged as an important target for anti-cancer therapies. Farnesyltransferase inhibitors have been introduced in clinical trials of subjects with colorectal cancer. We investigated Farnesyltransferase activity, beta-subunit Farnesyltransferase protein expression and its mRNA in patients with colorectal cancer and its relationship with clinicopathological features and K-ras mutation. Farnesyltransferase activity was determined by Farnesyltransferase [3H] SPA enzyme assay. Beta-subunit Farnesyltransferase protein expression was investigated by Western blotting and its mRNA by reverse transcriptase-polymerase chain reaction. K-ras mutation was detected by polymerase chain reaction amplification and restriction enzyme analysis. Multiple linear regression analysis was used to analyse relationships among age, sex, site of tumour, Dukes' stage, histological differentiation, K-ras mutation and Farnesyltransferase activity in normal mucosa and cancer. The levels of Farnesyltransferase activity and beta-subunit Farnesyltransferase protein expression were significantly higher in cancer than in normal mucosa. Moreover, tumours located on the right side, with mucinous histological differentiation and with K-ras mutation showed higher levels of Farnesyltransferase activity. Our findings suggest that Farnesyltransferase activity may be a potential marker of tumourigenicity. The differences in Farnesyltransferase activity in relation to histological grading, tumour location and K-ras mutation described here may constitute a starting point for investigating the causes of this variation within the large bowel.