Objective: To observe the spontaneous apoptosis in human non- small cell lung cancer (NSCLC) tissues, and the impact of PCNA and microvessel density on it.
Methods: TDT in situ labeling and immunohistochemistry were used to display apoptotic cells, PCNA and microvessels.
Results: The total forty-six cases of NSCLC were observed. Apoptosis index (AI) was 2.8% +/- 2.3% on average, and higher in squamous carcinomas (3.4% +/- 1.7%) than in adenocarcinomas (1.2% +/- 2.0%). AI in the poorly differentiated carcinomas (3.9% +/- 2.7%) was significantly higher than in the middle- and well-differentiated carcinomas (2.8% +/- 2.0%, 0.5% +/- 0.2% respectively). AI was higher in NSCLC with PCNA-positive cell rate >or= 25% (3.4% +/- 2.2%) than with PCAN-positive cell rate < 25% (1.9% +/- 2.2%). Microvessel density was higher in NSCLC with AI < 2% ( 74.4 +/- 29.6 counts/200 field) than with AI >or= 2% (42.0 +/- 12.8 counts/200 field). Apoptotic cells were frequently seen in the regions with less microvessels and distal to microvessels.
Conclusions: Spontaneous apoptotic cells mainly occur in the tissues of squamous carcinomas and poorly-differentiated carcinomas and NSCLC with higher PCNA-positive cell rates. Hypoxia could induce apoptosis of lung cancer cells.