OBJECTIVETo study the expression of caveolin-1 in primary lung cancer and its relationship with microvessel density and clinicopathologic parameters.

METHODSImmunohistochemical study for caveolin-1 and CD34 was performed on paraffin sections of 154 cases of primary lung cancer and adjacent non-neoplastic lung parenchymal tissue, as well as 36 cases with nodal metastasis. Microvessel density was analyzed by CD34 immunostaining. Western blot assay was also employed in tumor and non-neoplastic lung tissues of the 50 cases (25 cases of pulmonary squamous cell carcinoma and 25 cases of pulmonary adenocarcinoma) with fresh specimens available.

RESULTSImmunohistochemical study showed that non-neoplastic bronchial and alveolar epithelium was positive for caveolin-1 (membranous and cytoplasmic). The expression rate of caveolin-1 in lung cancer was 59.1%, which was significantly lower than that in normal lung tissues (P < 0.01). Western blot assay confirmed that the expression of caveolin-1 in pulmonary squamous cell carcinoma and adenocarcinoma was lower than in surrounding non-neoplastic lung tissues (P < 0.01). Caveolin-1 expression in pulmonary small cell carcinoma (7.1%) was significantly lower than that in non-small cell carcinoma (64.3%) (P < 0.01). Within the group of non-small cell carcinoma, the expression of caveolin-1 was much higher in patients with lymph node metastasis (P = 0.005). The expression was also higher in stage III and IV than in stage I and II disease (P = 0.042).

CONCLUSIONSThe expression of caveolin-1 is lower in lung cancer tissues than that in non-small cell carcinoma, it is also significantly correlated with tumor stage and lymph node metastasis. Caveolin-1 may play some role in the progression of pulmonary non-small cell carcinoma.