Effect of Conjugated Linoleic Acid (CLA) Supplementation on Expression of B-Cell Lymphoma-2 (Bcl-2) in the Bladder Epithelium of Wistar (Rattus norvegicus) Rats Exposed to Cigarette Smoke

Abstract

Background: Bladder carcinoma is the 10^th most common cancer in the world with an incidence about 3% of all cancers. The risk factor for smoking is found in 81% of all cases of bladder carcinoma. One of the protein groups associated with bladder urothelial carcinoma is B-Cell Lymphoma-2 (Bcl-2). Nicotine-derived nitrosamine ketone (NNK) contained in cigarette smoke would increase the proliferation of cancer cells through increased the expression of Bcl-2. The expression of Bcl-2 could be suppressed in the presence of Conjugated Linoleic Acid (CLA), a polyunsaturated fatty acid that has role in reducing the risk of cancer development which is reported in several studies, and then stimulate cell apoptosis.

Objective: To determine the effect of CLA supplementation on Bcl-2 expression in the bladder of rats which is exposed to cigarette smoke.

Methods: The study is an experimental study with true experimental posttest only control group design on Wistar rats. Sample was divided into 2 case groups: 0.5% of diet (125 mg) CLA supplementation in group A, 1% of diet (250 mg) CLA in group B; and 2 control groups: group without CLA supplementation (group C) as positive control and without cigarette smoke exposure (group D) as negative control. The study takes 60 days of exposure and then Bcl-2 expression on bladder epithelial was evaluated by immunohistochemistry staining.

Results: The results descriptively showed that rats in group C has an average Bcl-2 expression of 25.8±7.33%, while rats in group D has an average Bcl-2 expression 14.1±7.73% which means cigarette smoke exposure has been shown to increase the expression of Bcl-2 by 45.35% (p=0.019) in the bladder mucosa of experimental animals. Group B obtained an average Bcl-2 expression was 14.2±9.6% and has a significant difference when compared to group C, it shows that the addition of 1% CLA would reduce the expression of Bcl-2 by 44.96% (p=0.032). However, for group A, group with 0.5% diet of CLA supplementation did not showed decrease of Bcl-2 expression when compared to the group C (p=0.37).

Conclusion: Conjugated Linoleic Acid (CLA) supplementation 1% of diet can reduce Bcl-2 expression in bladder epithelium of wistar rats (Rattus norvegicus) exposed to cigarette smoke.

Keywords: Bcl-2; CLA; Cigarette smoke.