Production of prostate-specific antigen [PSA] by a breast cancer cell line, SK-Br-3

PSA is a 33-KDa serine protease that is produced predominantly by prostate epithelium. However, it has been shown that about 30-40% of female breast tumors produce PSA and its production is associated with the presence of estrogen and progesterone receptors. We have now developed a new tissue culture system to study PSA production in breast cancer and its association with prognostic factors such as progesterone receptor and c-erbB- 2. For this purpose we investigated the ability of PSA production in five different cell lines, including two breast cancer cell lines, SK-Br-3 and MDA-MB-453. The PSA in tissue culture supernatant and cytoplasm of the Sk-Br-3 cell line was detected by western blotting and immunoperoxidase, respectively. Furthermore, we found lower expression of c-erbB-2 in Sk-Br-3 than non-PSA producer breast cancer cell line, MDA-MB453. Progesterone receptor was expressed by both PSA-positive and -negative cell lines and only the intensity of staining and the number of positive cells in SkBr-3 population was higher than MDA-MB-453. According to our findings PSA can be considered as a good prognostic factor in breast cancer and we suggest that these two cell lines are a good in vitro model to study the relationship of different breast cancer prognostic factors and their regulations

Total cellular ribose nucleic acid analysis of multi-drug resistant cancer cells

The present study is designed to elucidate the correlation between gene dosage and increased messenger ribose nucleic acid [RNA] level in multi-drug resistant cancer cells. The human lymphoblasts CCRF-CEM [CEM] and CEM-vinblastine [VBL] 10, CEM-VBL 20, CEM-VBL 40, CEM-VBL 60, cell line CEM-VBL 80, and CEM-VBL 100 were derived from CEM VBL 10 by single step selection technique. For the analysis of total RNA and deoxyribonucleic acid [DNA], both Northern-Southern blot analysis were carried out on all sensitive and resistant cell lines. Part of the study was conducted at the Immunology Laboratory, Higher Institute of Health, Rome and the other part was conducted at the Middle Euphrates Center for Cancer Researches, Kufa University, Iraq, between 1990 and 2000. Total cellular RNA was analyzed to quantitate the levels of expression of multi-drug resistant-one gene with extent of its amplification in CEM-sensitive and resistant cell lines. Only the CEM-VBL resistant over-expresion the multi-drug resistant-one gene but in CEM-sensitive cells do not. The over-expresses appears to correlate proportionally with the level of drug resistance. No such correlation has been detected with regard to the genomic DNA. It appears that the first step in the transition from drug sensitive to drug resistant is increasing levels of messenger RNA followed by gene amplification. Furthermore, once the gene is amplified, it remains at the same level of amplification regardless of the concentration of drug in which given cells have been selected