Detection of group C adenovirus DNA in small-cell lung cancer with the nested polymerase chain reaction

Group C adenovirus is latent in human tissues and can malignantly transform cells. The purpose of this study was to investigate the association between this virus and lung cancer. We investigated latent adenoviral infection using the nested polymerase chain reaction and in situ hybridization in transbronchial biopsy specimens from patients with small-cell lung cancer and non-small-cell lung cancer. The polymerase chain reaction was performed on DNA extracts with two sets of primers directed at a 261-base-pair target sequence of the E1A region of the adenoviral genome. In situ hybridization was performed on histological sections using DNA representing the entire adenovirus type 5 genome. E1A target DNA was present in 11 (31%) of 35 cases of small-cell lung cancer but in none of the 40 cases of non-small-cell lung cancer (P < 0.01). Of the 11 cases found positive by PCR, 8 were positive for adenovirus DNA by in situ hybridization. Adenovirus was prominent in tumor cells in 5 of the 8 cases, and in normal epithelial cells in the 3 remaining cases. Adenovirus DNA was not detected by in situ hybridization in specimens in which E1A DNA was not detected by the polymerase chain reaction. Small-cell lung cancer has mutations or deletions in the p53 and retinoblastoma genes more frequently than are found in non-small-cell lung cancer. Therefore, we speculate that adenovirus infection might participate in the pathogenesis of SCLC by producing mutation in these genes, rather than by inhibiting the function of these proteins.