BACKGROUNDLivin is a novel inhibitor of apoptosis protein(IAP),recent studies showed that it overexpressed in many carcinomas including lung cancer and contributed much to the cancerous development.The objective of this study is to explore the expression of the two isoforms of livin in lung cancer tissues and their relationship with histological types and chemotherapy,and to explore their relationship to the expression of caspase-3 as well.

METHODSExpression of livin α,livin β and caspase-3 mRNAs were detected by reverse transcription polymerase chain reaction(RT-PCR) assay in lung cancer tissues as well as in controls.

RESULTSLivin α and livin β were expressed in 12 of 27 and 19 of 27 lung cancer tissues respectively,much higher than those in lung para-cancerous(0/6,0/6) or benign disease lung tissues(0/12,1/12)(both P < 0.01).Moreover,the positive rate was 7/14 and 9/14 in lung adenocarcinoma and 4/12 and 9/12 in squamous and large cell carcinoma respectively,and both of them were detected in one small cell carcinoma.The levels of these two isoforms in lung cancer were significantly higher than those in controls by Gel Imaging System(both P < 0.05),the level of livin α was remarkably higher in adenocarcinoma than that in squamous cell carcinoma(P < 0.05),while the level of livin β was similar in both carcinomas(P > 0.05).Meanwhile,the level of caspase-3 in lung cancer was significantly lower than that in controls,the levels of either each of two isoforms or their sum were negatively associated with that of caspase-3(P < 0.05,P < 0.01,P < 0.01).Two isoforms of livin mRNA expression seemed to increase after chemotherapy but not related to clinical stages(P > 0.05).

CONCLUSIONSTwo isoforms of livin are differently expressed in different histological types of lung cancer and may contribute to corresponding cancerous development;the levels of livin are negatively associated with those of caspase-3,this may due to the fact that livin could resist against apoptosis;high expression of livin seems to be related to chemotherapy but not clinical stage.