Differential expression of sonic hedgehog in lung adenocarcinoma and lung squamous cell carcinoma

Overexpression of Sonic hedgehog (Shh) is associated with progression of several cancers. The expression of Shh in non-small cell lung cancer (NSCLC) has been reported with inconsistent results. Lung adenocarcinoma (LAC) and lung squamous cell carcinoma (LSCC) are two major subtypes of NSCLC, which have different genetic genotypes and clinical therapeutic options. The expression of Shh in specimen of patients with NSCLC has yet to be comprehensively determined according to histological subtypes. Shh expression level was determined in 167 NSCLC patients (56 LAC patients and 111 LSCC patients) by immunohistochemical assay (IHC) and disease-free survival and overall survival of patients were analyzed using the Kaplan-Meier method. Shh protein level in pleural effusion from patients with pneumonia or pleural empyema, tuberculosis, LAC and LSCC was measured with enzyme-linked immunoassay (ELISA). We found that Shh expression is increased in tumor tissues from both LAC and LSCC patients compared with the paired adjacent tissues, while Shh level is negatively correlated with tumor differentiation only in LSCC, LSCC patients containing higher-Shh expression have a poorer prognosis. Furthermore, Shh level is elevated in pleural effusion from LSCC patients compared with that of parapneumonic and LAC pleural effusion. Shh expression in tumor tissues or pleural effusion may represent a potential diagnostic and prognostic marker of LSCC patients, pleural effusion Shh may assist to distinguish between LAC and LSCC.