Bcl-2 AND APOPTOSIS IN COLORECTAL CANCER: A MOLECULAR AND QUANTITATIVE ANALYSIS

Abstract

The importance of apoptosis in the pathology of disease, particularly cancer, has long been appreciated. It is well established that bcl-2 functions as a pro­ survival apoptosis regulator and has implications for anti-cancer therapy. Previous studies correlating apoptosis regulatory proteins with in situ apoptotic rates and with clinical outcome in colorectal carcinoma (CRC) have produced conflicting results.

In this study, clinical material and cell culture models were used. The quantitative assessment of apoptotic index (AI) and mitotic index (MI) and the

immunoreactivity of p53, bcl-2, p21wAF 1

1 and mdm2 were examined in

tumour and adjacent normal tissue samples from 30 patients with colonic and

22 with rectal adenocarcinoma. Individual features and combined profiles were correlated with clinicopathological parameters and patient survival data to assess their prognostic value. The induction of apoptosis and associated alterations in bcl-2, bax, p53, p21WAF 11c1 P 1 and mdm2 protein expression and distribution were examined pre- and post-H202 treatment in a panel of five human CRC cell culture models in vitro (HT115, LS174T, SW480, WiDr and CAC02). An accurate quantitative assessment of bcl-2 expression was performed using flow cytometric (FCM) analysis and the relationships between bcl-2 protein expression, apoptosis and cell cycle changes were investigated in the CRC cell lines pre- and post-H202 treatment. The subcellular localisation and distribution of bcl-2 and bax proteins throughout the CRC apoptotic cells were examined using confocal laser scanning