BACKGROUNDThe epidermal growth factor receptor tyrosine kinase inhibitor(EGFR-TKI) is playing an important role in the treatment of non-small cell lung cancer.The acquired resistance of EGFR-TKI has become a hot spot.This study aims to investigate VEGF-D expression level in lung adenocarcinoma with or without acquired resistance to gefitinib and in normal lung,so as to explore the role of VEGF-D in resistance of gefitinib.

METHODSLung adenocarcinoma,normal lung tissues adjacent to the carcinoma and adenocarcinoma with acquired resistance to gefitinib including some metastastic lymph nodes were obtained during operation.SYBR Green real-time PCR with beta actin gene as the endogenous control was performed to examine VEGF-D gene expression semi-quantitatively.After positive expression of VEGF-D was determined,the expression ratio and level in each group was analyzed qualitatively and quantitatively.

RESULTSExact significance was computed to compare VEGF-D expression ratios in groups of lung adenocarcinoma with acquired resistance to gefitinib(1/6,16.7%),lung adenocarcinoma(7/14,50.0%) and normal lung(16/16,100.0%) and the difference was significant(P=0.000 091 7).VEGF-D relative expression level in the seven lung adenocarcinoma cases was significantly lower than its corresponding normal lung tissue by analysis of nonparametric test(P < 0.01).

CONCLUSIONSVEGF-D has a high-level expression in normal lung tissues,while has a decreased expression in lung adenocarcinoma with or without acquired resistance to gefitinib,suggesting that VEGF-D functions in lung adenocarcinoma with or without acquired resistance to gefitinib in a way,which is different from in normal lung.