RESUMO
<p><b>BACKGROUND</b>To study the expression of catalylic subunit of DNA-dependent protein kinase (DNA-PKcs) in non-small cell lung cancer (NSCLC) and its relationship with apoptosis.</p><p><b>METHODS</b>NSCLC tissues from 113 untreated patients were analyzed immnohistochemically with antibodies to DNA-PKcs, p53 and bcl-2.</p><p><b>RESULTS</b>There were expressions of DNA-PKcs, p53 and bcl-2 in NSCLC at different levels. The positive rate of DNA-PKcs, p53 and bcl-2 was 89.38%(101/113), 61.95%(70/113) and 59.29%(67/113) respectively. The expression of DNA-PKcs was significantly related with the histological types. Its expression in squamous carcinoma was significantly lower than that in adenocarcinoma and bronchioloalveolar carcinoma. The expression of DNA-PKcs increased with the increasing differentiated degree of NSCLC ( P < 0.05), but had no relationship with lymph node metastasis. There was no significant relation between the expression of p53 and the pathological type of NSCLC. A significant difference of bcl-2 expression existed in the histological types of lung cancer ( P < 0.01). Its expression in squamous carcinoma was significantly higher than that in adenocarcinoma, bronchioloalveolar carcinoma and adenosquamous carcinoma, but had no relationship with the differentiated degree of lung cancer and lymph node metastasis. The expressions were significantly related between DNA-PKcs and p53 ( P < 0.01), p53 and bcl-2 ( P < 0.05).</p><p><b>CONCLUSIONS</b>The expression of DNA-PKcs is fairly high in NSCLC. The high expression of DNA-PKcs and overexpressions of mutated p53 and bcl-2 may be important causes of radioresistance in NSCLC.</p>