GABARAP is Overexpressed in Colorectal Carcinoma and Correlates with Shortened Patient Survival

Background/Aims: gamma-aminobutyric acid type A (GABAA) receptor associated protein (GABARAP), the mammalian homologue of yeast Atg8, is involved in autophagosome formation during autophagy. The aim of this study is to explore the expression and its prognostic significance in comparison with various clinicopathological predictors of survival. Methodology: GABARAP protein expression was determined by immunohistochemistry in 103 colorectal cancers. Cytoplasmic immunoreactivity was scored semiquantitatively. The results were analyzed in correlation with various clinicopathological variables, including patient survival. Chi-square test and Kaplan-Meier survival analysis were applied. Results: The expression of GABARAP was significantly higher in colorectal cancers than that in adjacent matched nontumor tissues (51.5% vs 33.0%, p<0.01). Increased expression of GABARAP expression in colorectal cancers was significantly correlated with a low grade of differentiation and shortened overall survival (p<0.05). There were no significant differences between the expression of GABARAP and age, gender, stage, tumor size, location of primary tumor, and lymph node invasion. Conclusions: Our data demonstrated that GABARAP is frequently expressed in colorectal cancer. Overexpression of GABARAP is a new independent prognostic marker, which is associated with poor differentiation as well as shortened overall survival.