Malignant transformation of Syrian hamster embryo (SHE) cells in culture by malachite green: an agent of environmental importance.

Malachite green (MG), consisting of green crystals with a metallic lustre, is very soluble in water and is highly cytotoxic to mammalian cells in culture and also acts as a liver tumour promoter. In view of its industrial importance and possible exposure to human beings, MG poses a potential environmental health hazard. Accordingly, we have studied the effect of MG on the formation of free radicals using Electron Spin Resonance (ESR) analysis with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent. ESR analysis showed formation of reactive free radicals during exposure of MG to Syrian hamster embryo (SHE) cells. As per mechanism-based toxicology in cancer risk assessment, the chemicals that have the potential to be metabolized to active free radical species could be human cancer hazards. So, we have investigated the effect of MG on the formation of Type II and Type III morphologically transformed foci using SHE cell transformation assay. MG induced dose related transformed foci. Some of these transformed foci were taken out using selective trypsinisation and established immortal cell lines. One of these immortal cell lines was characterized extensively. This immortal cell line showed enhanced DNA synthesis in the form of BrdU incorporation, increased presence of proliferating cell nuclear antigen (PCNA), bcl-2 and p53 proteins by immunohistochemistry. When these immortal cells were injected subcutaneously into nude mice, they developed tumors which were transplantable and histopathologically sarcomas. The present studies indicate that MG could be a potential candidate for two year chemical carcinogenesis rodent bioassays.

DNA analysis of breast cancer by flow cytometry & correlation with other prognostic parameters.

Flow cytometric estimation of DNA content (ploidy and S-phase fraction--SpF) was done on breast cancer tissues from 171 patients. Twenty eight per cent of the tumours were diploid and 72 per cent were aneuploid. SpF was measurable in 82 DNA histograms; of these 22.4 per cent had SpF less than 10 per cent, 34.1 per cent had SpF between 10-20 and 43.5 per cent had SpF greater than 20 per cent. The mean SpF of the measurable histograms was 19.01 per cent with a range 1.78 to 45.19 per cent. A significant correlation between DNA ploidy and SpF was observed (P less than 0.01). Eighty nine per cent of diploid tumours had SpF less than 10 per cent and 73 per cent of aneuploid tumours had SpF greater than 20 per cent. A significant correlation was also found between ploidy and SpF and oestrogen receptor (ER) status of the tumours (P less than 0.05) and between SpF and progesterone receptor (PgR) status of the tumours (P less than 0.05), but not between ploidy and PgR status of the tumours. A significant direct correlation was observed between SpF and tumour grade (P less than 0.05), but not between ploidy and tumour grade. No correlation was observed between DNA ploidy and SpF and tumour type, tumour size, axillary lymph node involvement, age and menopausal status of the patients. Although the incidence of breast cancer is one-third of that reported in the Western countries, there is apparently no biological difference between the various parameters studied.

Estrogen & progesterone receptors measurement in breast cancer with enzyme-immunoassay & correlation with other prognostic factors.

Estrogen and progesterone receptor (ER and PgR) estimation was carried out by an enzyme-immunoassay by a 'sandwich' technique using two different monoclonal antibodies against each receptor on 508 consecutive breast cancer samples. 43.9 per cent of the tumours were ER+ve and 26.6 per cent were PgR+ve; 23.8 per cent were both ER and PgR+ve, 53.3 per cent were both ER and PgR-ve, 20.0 per cent were ER+ve PgR-ve and 2.8 per cent were ER-ve PgR+ve. Both ER and PgR positivity was associated with increasing age, and this was seen within both pre and post-menopausal subgroups. Grades I and II tumours were more often ER and PgR+ve compared with grade III tumours, indicating that receptor positivity is a marker of a more well differentiated tumour phenotype. Receptor positivity was higher in primary tumours compared to that in metastatic tissues. The proportion of tumours that was ER+ve was found to vary among the four major religious communities, viz., Hindu, Muslim, Christian and Parsi, and this variation was significant in the overall analysis (P less than 0.01). The Christians had the highest rate of ER+ve tumours while the Muslims had the lowest rate. No correlation was observed between ER and PgR status and axillary nodal involvement or tumour size, suggesting that ER and PgR are independent prognostic factors in breast cancer. We found the EIA method to be an easy and rapid technique for ER and PgR analysis and which requires a small amount of tissue and does not involve the use of radioisotopes.

Differences in oestrogen receptor status and histological grade of breast cancer in different religious communities in Bombay.

The various religious communities in India viz.Hindu, Muslim, Christian, Parsi have different breast cancer incidence rate. It is not known whether there might also exist differences in biological properties of breast cancer between these communities. To investigate this possibility we have studied the distribution of oestrogen receptor (ER) status and histological grade of tumour in these four communities. Significant differences were observed in the overall distribution of ER positivity and histological grade between the communities P less than for both parameters). Christians had the highest incidence of ER +ve (65.2%) and grade I + II tumours (16.0%), while Muslims had the lowest incidence of ER +ve (35.8%) and Grade I + II tumours (4.7%). In general, we found a significant positive relationship between ER status and age of the patient (p less than 0.0.1). The mean age of the christians was slightly but significantly higher than that of the Hindus and Muslim. The difference ER positivity between the communities might, therefore, be partly (but probably not wholly) explained by difference in age of the patients. However, the difference with respect to grade of tumour cannot be explained as a function of age since no significant association was found between grade of the tumour and age of the patient. Further investigation with respect to difference in the biology of the breast cancer between the communities are warranted.

A comparative study of dextran coated charcoal (DCC) and enzyme immunoassay (EIA) methods for oestrogen receptor (ER) estimation in breast cancer.

Oestrogen receptor (ER) concentrations were measured in 100 breast cancer cytosols using both the dextran coated charcoal assay (DCC with 6--point scatchard plot) and a newly developed enzyme linked immunoassay (EIA) using a monoclonal antibody against ER. The efficiency of the two methods was compared. A highly significant correlation was observed between the ER levels determined by DCC and EIA methods (r = 0.94, p less than 0.001). The mean ER-EIA value (43.25 +/- 74.77) was, however, significantly higher than the mean ER-DCC value (18.00 + 37.27) (p less than 0.001); in both pre- menopausal (p less than 0.001) and post-menopausal (p less than 0.001) groups. Using a cut-off point at 10 fmo/mg protein for ER-EIA and 3 fmol/mg protein for ER-DCC/to distinguish ER +ve and -ve tumours, a 97% concordance between the two assays was achieved. The EIA method appears to be preferable to the DCC method because it is easy to perform, rapid, requires less tissue and does not involve the use of radioactive substances.