Role ofBcl-2, Bax, andBak in spontaneous apoptosis and proliferation in neuroendocrine lung tumors: Immunohistochemical study

Abstract
Fifty-six primary neuroendocrine lung tumors were examined morphologically and histologically and their apoptosis level was determined. Malignant carcinomas were characterized by increased apoptotic index and enhanced expression ofBcl-2, Bak, p53, andKi-67 compared to typical carcinoid. However, apoptosis in these tumors was not completed. Proteins of theBcl family play an important role in the regulation of spontaneous apoptosis in neuroendocrine lung tumors.Bcl-2 accumulating in the nucleus is a morphological analogue of phosphorylated inactive form of this protein, which does not inhibit apoptosis. Expression ofBcl-2 andBax decreases in small-cell lung carcinoma (SCLC) with metastases indicating attenuation of apoptosis and development of metastatic clones resistant to apoptosis induces.