OBJECTIVETo investigate the expression of connexin 43 and E-cadherin in lung cancer and to study the interaction between the two molecules.

METHODSThe expression and correlation of connexin 43 and E-cadherin were evaluated by immunohistochemistry (S-P method) in 85 samples of primary squamous cell carcinoma and adenocarcinoma of the lung. In addition, connexin 43 expression vector was transfected into the lung giant cell carcinoma cell line LH(7) followed by analyses of connexin 43 and E-cadherin expressions, the growth rates and cell cycle profiles of the transfected cells.

RESULTSComparing with the adjacent non-neoplastic lung tissue, expression of connexin 43 and E-cadherin was decreased in a correlative fashion in both squamous cell carcinomas and adenocarcinomas. Their expression reversely correlated to the degree of tumor cell differentiation, P-TNM stage, and status of lymph note metastasis. The expression of connexin 43 and E-cadherin increased significantly after transfection of connexin 43 expression vector into the LH(7) cells (P < 0.05). Both expressions were limited in the cytoplasm before or after the transfection. The proliferation rate of LH(7) cells was significantly decreased by connexin43 expression (P < 0.05), along with an increase of cell population at G(1) phase and a decrease of percentage of cells in S and G(2) phases (P < 0.05).

CONCLUSIONSSquamous cell carcinoma and adenocarcinoma of lung have a low level of connexin 43 and E-cadherin expression, which are correlated with the clinicopathologic features of the tumors. Transfection expression of connexin 43 gene induces an E-cadherin overexpression and an inhibition of LH(7) cell proliferation indicating the significant role of onnexin 43 in the regulation of cell proliferation.