The Expression And Significance Of Retinoic Acid Binding Protein In Colorectal Cancers

Background and purpose Retinoic acid(RA)can perform the functions of adjusting cell differentiation,inhibiting cell growth and inducing cell apoptosis by combining with and activating retinoid X receptor(RXR).This process is regulated and controlled by the cellular retinoic acid binding protein Ⅱ,CRABP-Ⅱ.On the contrary,RA can also perform the functions of promoting cell cornification and proliferation,as well as resisting cell apoptosis,by combing with and activating peroxisome proliferator-activated receptor β/δ,PPARβ/δ.But this process is regulated and controlled by the fatty acid-binding protein,epidermal,FABP5.The purpose of this study is to explore the expression and significance of CRABP-II and FABP5 in the cancer tissues and pericarcinous tissues of colorectal cancers.Method Testing the expressions of CRABP-II and FABP5 in the cancer tissues and corresponding pericarcinous tissues of 35 colorectal cancer patients by means of tissue array and immunohistochemical staining technique.Results The expression of FABP5 in the primary cancer tissues of colorectal cancers is significantly higher than that of CRABP-Ⅱ(P<0.05),and the expression of FABP5 in the pericarcinous tissues of colorectal cancers is also higher than that of CRABP-II(P<0.05).The expression of CRABP-II in the primary cancer tissues of colorectal cancers does not seem to be significantly correlated with gender(P=0.677),age(P=0.370),diameter of cancer(P=0.928),depth of invastion(P=0.497),degree of differentiation(P=0.727),tumor type(P=0.491),occurrence/non-occurrence of metastasis(P=0.497),and TNM staging(P=0.677).However,at the site where the primary cancer tissues of a colorectal cancer exist,the positive expression rate of CRABP-II which occur in the colon cancer tissues is significantly higher then that occurring in the rectum and the ileocecal junction(P=0.041).The expression of CRABP-II and FABP5 in the pericarcinous tissues of colorectal cancers does not show any strong correlation with such clinicopathologic features as gender,age,degree of differentiation,occurrence/non-occurrence of metastasis,etc.In the primary cancer tissues and pericarcinous tissues of colorectal cancers,the distribution of(-),(+),(++)and(+++)expressed by CRABP-II and FABP5 differs from that of FABP5,whereas in both cases the positive expressions of FABP5 prevail.Conclusion CRABP-II and FABP5 play a very important role in the oncogenesis and development of tumors.In comparison with CRABP-II,FABP5 demonstrates a higher expression rate in the cancer tissues and pericarcinous tissues of colorectal cancers.It seems likely that the more prevailing the expressions of FABP5 are,the greater will be the size,scope and diameter of the tumor,and therefore there will be a higher probability for a tumor matastasis to take place.