Apoptosis and gastric carcinogenesis: Immunohistochemical analysis of Bax and Bcl-2 proteins

Abstract

Aim: Our aim was to evaluate the role of Bax and Bcl-2 apoptosis-
related proteins in the carcinogenesis of the stomach.
Materials and Methods: 80 biopsy specimens and 50 surgical
specimens of chronic gastritis, atrophic gastritis, intestinal
metaplasia, gastric dysplasia and gastric cancer were studied.
Routine hematoxyline and eosin sections were evaluated
and classified according to the latest diagnostic criteria.
Immunohistochemical methods were used for detection of
Bax and Bcl-2. Results: The expression of Bax in precancerous
lesions and in gastric cancer was distributed as follows:
chronic gastritis 100% (80/80 cases), atrophic gastritis 60%
(39/65 cases), intestinal metaplasia 55% (28/50 cases), dysplasia
25% (10/40 cases), intestinal type adenocarcinoma 40%
(12/30 cases), and diffuse type adenocarcinoma 15% (3/20
cases). Bcl-2 expression was as follows: chronic gastritis 0%,
atrophic gastritis 35% (23/65 cases), intestinal metaplasia
90% (45/50 cases), dysplasia 100% (40/40 cases), intestinal
type adenocarcinoma 83.3% (25/30 cases), and diffuse type
adenocarcinoma 70% (14/20 cases). Conclusions: Our findings
demonstrate the high expression of Bcl-2 in precancerous
lesions (intestinal metaplasia, dysplasia) and in gastric
cancer; at the same time the suppression of Bax in these diseases
is evident. This highlights the major role of Bcl-2 and
the contradicting role of Bax in early carcinogenesis.
Key Words: apoptosis, gastric carcinogenesis, Bax, Bcl-2