The assessment of in vitro modulation of milk fat globule membrane expression by human breast carcinomas

MUC-1 mucin in normal human salivary glands detected by HMFG-1 and HMFG-2 monoclonal antibodies

The aim of this study was to determine the immunoexpression of normal salivary gland cells using two human milk fat globule membrane protein antibodies (HMFG-1 and HMFG-2). Paraffin-embedded, 5 microm-thick slides from parotid and submandibular gland tissues were cut and immunostained with monoclonal antibodies HMFG-1 and HMFG-2 against MUC1 protein. HMFG antigens were found in secretory epithelial cells and ductal cells lining the striated and intercalated ducts in the intraductal secretion material, and sometimes in the myoepithelial cells. Our results suggest that HMFG-1 and HMFG-2 proteins may play a role in normal salivary gland function, mainly in the manufacturing and secretion of saliva.

Modulation of cell surface components of human breast cancer cells by retinoic acid: enhanced HLA-DR expression

The effect of the differentiating agent all-trans-retinoic acid on the expression of components of the milk fat globule membrane and HLA-DR by breast cancer cell lines has been examined. Effects on proliferation were also considered, to determine whether any cell surface changes were related to or independent of proliferation effects. No significant differences were observed in the expression of components detected by the milk fat globule membrane antibodies HMFG1 and HMFG2 over 8 days culture with 10(-7)-10(-9)M retinoic acid for the cell lines MCF-7, T-47 D, ZR-75, MDA-MB-231, and BT-20. In contrast , there was enhanced expression of HLA-DR by two oestrogen receptor-positive cell lines T-47 D and ZR-75 and the oestrogen receptor-negative line MDA-MB-231, with differing sensitivities. These effects were independent of inhibition of proliferation, which was only observed for oestrogen receptor-positive cell lines and for different durations of exposure. The finding of enhanced HLA-DR expression after retinoic acid treatment has not previously been reported and is of interest regarding clinical potential for the induction of tumour immunity.

In vitro modulation of cellular localization of milk fat globule membrane antigens in human breast carcinomas

Alterations in the cellular localization of cell surface components such as the milk fat globule membrane are a common feature of breast carcinomas and relate to the differentiation of a tumour. This study has examined the potential modulation of such components. A group of carcinomas were cultured with and without insulin and/or hydrocortisone and the site of staining for milk fat globule membrane, as detected by the antibodies HMFG 1, HMFG 2, and NCRC 11, was assessed using light microscopic and electron microscopic immunohistochemistry. Modulation of localization, with a shift from cytoplasmic vesicle labelling to submembraneous vesicles/cell surface labelling and intracytoplasmic luminal labelling, was observed in 5 of 14 moderately differentiated and 8 of 11 poorly differentiated carcinomas. Two well differentiated carcinomas continued to show peripheral labelling; three poorly differentiated carcinomas showed no change from cytoplasmic labelling only; and the other carcinomas exhibited heterogeneous localization, making any change difficult to assess. Insulin was required for any change to be observed and it is suggested that this has an effect on the mechanisms for intracellular transport of membrane and secretory proteins.

Patterns of reactivity with the monoclonal antibodies HMFG1 and HMFG2 in normal endometrium, endometrial hyperplasia and adenocarcinoma

Using an indirect immunoperoxidase technique the expression of the epitopes in human milk fat globule (HMFG) membranes detected by the monoclonal antibodies HMFG1 and HMFG2 was studied in the normal endometrium and in cases of cystic glandular hyperplasia, glandular hyperplasia with architectural atypia (complex hyperplasia), glandular hyperplasia with cytological atypia (atypical hyperplasia) and invasive adenocarcinoma. Luminal reactivity with HMFG1 was seen in cases of normal endometrium, cystic glandular hyperplasia and glandular hyperplasia with architectural atypia. In contrast most cases of glandular hyperplasia with cytological atypia and invasive adenocarcinoma also showed areas of cytoplasmic reactivity. Reactivity with HMFG2 was scanty.