Expression of Fatty Acid-binding Protein 5 and Cellular Retinoic Acid-binding Protein 2 in Gliomas

Objective To investigate the correlation between the expression of fatty acid-binding protein 5 (FABP5) cellular retinoic acid-binding protein 2 (CRABP2) and WHO grades as well as the retinoic acid resistance of glioma. Methods Immunohistochemistry staining was applied to detect FABP5 and CRABP2 protein expression in 125 brain astrocytoma samples. Brdu-ELISA was applied to detect the proliferation and real-time quantitative fluorescence PCR was performed to detect mRNA expression of the two proteins in glioma cell lines before and after all-trans retinoic acid (ATRA) treatment. Results The percentage of FABP5 positive cells was (16±9)% in glioma samples of WHO grade Ⅱ, (33±22)% in WHO grade Ⅲ and (50±29)% in WHO grade Ⅳ; FABP5 expression was positively correlated with WHO grades of glioma (P<0.05). The percentage of CRABP2 positive cells was (46±12)% in glioma samples of WHO grade Ⅱ, (30±15)% in WHO grade Ⅲ and (10±9)% in WHO grade Ⅳ; CRABP2 expression was negatively correlated with WHO grades of glioma (P<0.05). ATRA promoted the proliferation of glioma cell lines. Moreover, after ATRA treatment, FABP5 mRNA expression was increased while CRABP2 mRNA expression was decreased significantly. Conclusion The abnormal expression of FABP5 and CRABP2 are closely associated with glioma grades and may play roles in the retinoic acid resistance of glioma.