RESUMO
OBJECTIVE: Tuberculosis is one of the most infectious diseases worldwide and lung cancer is one of the leading causes of death. The major contagious agent for tuberculosis, Mycobacterium tuberculosis (M. tuberculosis), has been well studied for its pathogenicity. Even though there are studies showing that patients with a history of tuberculosis are more likely to develop lung cancer, the association between M. tuberculosis and lung cancer largely remains unknown. In this study, we used in situ hybridization to analyze lung tissues from patients who underwent surgical resection or bronchoscopy for the expression of M. tuberculosis-specific gene, mpb64, to provide evidence for the association of M. tuberculosis L-form to the occurrence of lung cancer. PATIENTS AND METHODS: Experiments were conducted in the lung cancer group (80 cases), pulmonary tuberculosis group (80 cases) and pulmonary tuberculosis plus lung cancer group (77 cases). For each group of tissue samples, in situ hybridization was used to detect the expression of mpb64 gene fragment in cell nuclei. RESULTS: Mpb64 gene was positively expressed in 45% (CI: 38.63-51.37) of the cancerous cell nuclei. When compared to the expression level of 66.25% (CI: 59.88-72.62) in the pulmonary tuberculosis cells, the difference was statistically significant (p=0.007). However, when compared to the expression of 49.35% (CI: 42.98-55.72) in pulmonary tuberculosis plus lung cancer cells, the difference was not statistically significant (p=0.585). Mpb64 gene expression level was independent from the different tissue types, pathological stages, or metastasis situations in the lung cancer group (p>0.05). CONCLUSIONS: The mpb64 gene fragment is highly expressed in the nucleus of pulmonary tuberculosis tissues. Its expression in the nucleus of pulmonary tuberculosis plus lung cancer tissue is significant and the expression in the nucleus of lung cancer tissue is also high. The expression of mpb64 is independent from the various pathological features of the cancerous tissues. Taken all together, we provided evidence for the correlation of M. tuberculosis L form and the occurrence of lung cancer. Thus, patients with a history of tuberculosis may be more likely to develop lung cancer than those without a history of tuberculosis.
