Relationship between apoptosis and immunohistochemical staining for proliferating cell nuclear antigen and Ki-67 in non-small cell lung cancer

The relationship between apoptosis and cellular proliferative activity in human non-small cell lung cancer (25 cases) was investigated using the in situ DNA nick-end labeling method and immunohistochemistry for both proliferating cell nuclear antigen (PCNA) and Ki-67 antigen. Comparison of the distribution of Ki-67-positive cells to that of apoptotic cells shows an inverse correlation in semi-serial sections. The PCNA labeling rates were closely correlated with Ki-67 labeling rates in non-small cell lung cancer. It was concluded that the immunostainings of PCNA and Ki-67 were almost equally valuable for assessing the proliferative activity in paraffin-embedded tissue from non-small cell lung cancer and that apoptosis may be related with the cell cycle in this cancer.