Abstract
Immunohistochemical staining of bcl-2 and p53 proteins was compared with thymidine labelling index (TLI) and cell loss factor (O) in lung cancer. Neither bcl-2 nor p53 overexpression was associated with high cell loss but strong bcl-2 staining was associated with higher TLI. Concomitant strong p53 and bcl-2 expression, not the usual inverse relationship, plus high cell-loss factor was present in three neuroendocrine carcinomas. Other factors presumably have a role in controlling cell death in these tumours.
Highlights
Apoptosis is a major mechanism of tumour cell loss, itself a major determinant of tumour growth rate, and the protein products of both the p53 and bcl-2 genes have a role in this process
We investigate the relationship between the cell proliferation/loss data in these 17 human lung tumours and their expression of the p53 and bcl-2 genes assessed immunohistochemically
Of the differentiated primary lung carcinomas, excluding case 5, bcl-2 staining was negative or weak whereas p53 staining was recorded at all grades
Summary
The histological classification of the tumours required revision of the original (Kerr and Lamb, 1984). 'Large-cell carcinoma with stratification' is classified as poorly differentiated squamous carcinoma. Thought originally to be a metastatic deposit of large-cell carcinoma, with follow-up, fulfils criteria of a primary large-cell neuroendocrine cancer. Thirteen of the cases were typical bronchogenic carcinomas (six squamous, three adenocarcinoma, two small-cell undifferentiated, one largecell neuroendocrine and one large-cell undifferentiated carcinoma). Two were renal cell carcinoma metastases and one a primary clear cell carcinoma. Labelled cells were visualized and counted on autoradiographs of tissue sections (Kerr et al, 1983). Knowledge of the tumour cell population TLI allows the potential doubling time (DTpot) to be estimated. From DT and DTpot data, the cell loss factor (0) was calculated (Steel, 1967)
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