Chinese Journal of Lung Cancer (Oct 2008)
The expression of ABCG4, V-ATPase and clinic significance of their correlation with NSCLC
Abstract
Background and objective It has been proven that the multiple drug resistance is main reason for failure of chemotherapy in lung cancers and ABC transporter play a main role for chemoresistance in mediating drug efflux. So searching for new drug resistant protein of the ABC family and elucidating its resistant mechanism is very important. ABCG4 is one of ABC family and is expected to be candidate drug resistant protein; and the drug resistance probably correlated with pH value around cancer cell, while, V-ATPase play key role in modulating the pH. So our aim is to investigate the expressions of ABCG4, V-ATPase proteins in non small cell lung cancer (NSCLC), and analyze relationship of ABCG4, V-ATPase protein expressional rate in these cancers with the cancers' pathological grade and TNM stages. Methods To detect the expression rates of ABCG4, V-ATPase protein in NSCLC with immunohistochemical method and immuno- fluorescent method, and to observe the location, the collocation of the proteins under light microscope and confocal laser scanning microscope; the differences of the protein expression and their correlations wereanalyzed by statistics. Results ABCG4 protein was high expressed in squamous cell lung cancer, lung adenocarcinoma respectively, and between the two kinds of the cancers there was a significant difference (P =0.001) for their comparison;there were significant differences between pathological grade ⅡandⅡ-Ⅲ of squamous cell lung cancer, between different differentiated lung adenocarcinoma. V-ATPase protein were also high expressed in these two kinds of cancers, and there was significant difference for their comparison; there were significant differences between pathological grade ⅡandⅡ-Ⅲ of squamous cell lung cancer, between different differentiated lung adenocarcinoma; there were no significantdifferences among the squamous cell lung cancer and lung adenocarcinoma for TNM stages respectively. The P values of correlationship test of positive intensity between ABCG4 and V-ATPase expression in the total squamous cell lung cancer and lung adenocarcinoma, in the pathological grade Ⅱand Ⅱ-Ⅲ of the squamous cell lung cancer, in the moderately differentiated lung adenocarcinoma were all 0.000, while the correlation coefficients were 0.771, 0.765, 0.714, 0.777, 0.865 respectively; however, the P values of correlationship test of between ABCG4 and V-ATPase expression in the low differentiated lung adenocarcinoma was 0.048, and the correlation coefficient was 0.35. The ABCG4 and V-ATPase positive expression was mainly located in the plasma membrane and cytoplasm, and there was collocation among the ABCG4 and V-ATPase proteins. Conclusion The ABCG4 and V-ATPase proteins are highly expressed in the NSCLC,and the expression rates of ABCG4, V-ATPase proteins are correlated with the cancers' pathological grades and TNM stage; and there are all having correlationship between ABCG4 and V-ATPase proteins in the squamous cell lung cancer,in the lung adenocarcinoma, in all their pathological grades.
