Expression of HO-1 in human lung cancer and its correlation with clinical data

Abstract

An increasing amount of evidence indicates that HO-1 activation may play a role in carcinogenesis, potently influencing the growth and metastasis of tumors. Although several reports show a role for HO-1 in lung cancer, little is known about enzyme expression in human lung cancer specimens. Therefore, the aim of this work was to sudy HO-1 expression in human lung carcinoma samples and its correlation with clinicopathological data. As a first approach we tested HO-1 expression in 16 paraffin embedded tumor specimens. Positive protein immunostaining was observed in 75% (12) of the samples analyzed and HO-1 was mainly expressed by carcinoma cells. In order to perform a wide screening of HO-1 expression in lung cancer we used a tissue microarray (TMA) consisting of 330 cores including non-malignant lung tissue, adenocarcinoma, squamous cell carcinoma, carcinoid tumors, small cell carcinoma and large cell carcinoma.92% of tumor samples were positive for HO-1 and protein expression correlated with advanced satges (p=0.021, X2), lymph node involvement (p=0.025), and gender (p=0.036). Additionally we performed RT-PCR in 19 samples of human lung carcinomas, detecting HO-1 mRNA in 84% of them. A significant correlation was observed between HO-1 mRNA levels and smoking habit (p=0.004) and T staging (TNM, p=0.001). In summary, these results present additional evidence of an important role for HO-1 in lung cancer.