Alteration in key oncoprotein expression in gastric adenocarcinoma - An immunohistochemical study

This study was conducted to evaluate the frequency and clinicopathologic correlates of human epidermal growth factor receptor 2 (HER-2)/neu and betacatenin (BC) oncoproteins in gastric adenocarcinoma and to seek correlation if any between their expression status.

This cross-sectional analytical immunohistochemistry (IHC) study was performed on 50 cases of gastric adenocarcinoma. HER-2/neu immunoexpression was scored as per criteria by Ruschoff et al. as positive (3+), equivocal (2+), and negative (1+, 0). Aberrant BC expression was categorized as nuclear, cytoplasmic, and reduced membranous immunoexpression. Protein expression results of both oncoproteins were correlated with conventional clinicopathological parameters. Correlation between immunoexpression profiles of both proteins was also analyzed. P <0.05 was considered statistically significant.

HER-2/neu positivity (2 + and 3+) was seen in 94% of the cases; almost 60% had strong (3+) expression. All cases showed aberrant BC immunoexpression (any pattern) except 2 cases that revealed negative expression (a form of aberrant immunoexpression) and were removed from analysis due to a very small number. The pattern of BC expression was as follows: nuclear expression (38%), cytoplasmic expression (82%), reduced membranous expression (96%), no staining (4%) cases. HER-2/neu expression correlated with age. No significant correlation was found between any of the 2 oncoprotein immunoexpression and other clinicopathological parameters (P > 0.05). Concordance between protein expression of HER-2/neu and BC was seen in >93% cases, however, the correlation was not significant.

HER-2/neu and BC oncoprotein expression are frequently dysregulated in gastric adenocarcinomas. The significance of pathways involving HER-2/neu and BC in gastric carcinogenesis should be explored.