Cell-type specificity of β-actin expression and its clinicopathological correlation in gastric adenocarcinoma

AIM:To investigate cell type specific distribution ofβ-actin expression in gastric adenocarcinoma and its correlation with clinicopathological parameters.METHODS:β-actin is a housekeeping gene,frequently used as loading control,but,differentially expresses in cancer.In gastric cancer,an overall increased expression ofβ-actin has been reported using tissue disruptive techniques.At present,no histological data is available to indicate its cell type-specific expression and distribution pattern.In the present study,we analyzedβ-actin expression and distribution in paired normal and tumor tissue samples of gastric adenocarcinoma patients using immunohistochemistry(IHC),a tissue non-disruptive technique as well as tissue disruptive techniques like reverse transcriptase-polymerase chain reaction(RT-PCR)and western blotting.Correlation ofβ-actin level with clinicopathological parameters was done using univariate analysis.RESULTS:The results of this study showed significant overexpression,at both mRNA and protein level in tumor tissues as confirmed by RT-PCR(1.47±0.13 vs2.36±0.16;P<0.001)and western blotting(1.92±0.26 vs 2.88±0.32;P<0.01).IHC revealed thatβ-actin expression is majorly distributed between epithelial and inflammatory cells of the tissues.Inflammatory cells showed a significantly higher expression compared to epithelial cells in normal(2.46±0.13 vs 5.92±0.23,P<0.001),as well as,in tumor tissues(2.79±0.24 vs6.71±0.14,P<0.001).Further,comparison of immunostaining between normal and tumor tissues revealed that both epithelial and inflammatory cells overexpressβ-actin in tumor tissues,however,significant difference was observed only in inflammatory cells(5.92±0.23vs 6.71±0.14,P<0.01).Moreover,combined expression in epithelial and inflammatory cells also showed significant increase(4.19±0.15 vs 4.75±0.14,P<0.05)in tumor tissues.In addition,univariate analysis showed a positive correlation ofβ-actin level of inflammatory cells with tumor grade(P<0.05)while epithelial cells