Development of tumorigenicity and rearrangement of chromosome 1 correlates with down-regulation of cell-surface glycoproteins in human mammary carcinoma cell line.

In the current study, attempts were made to identify any products of normal breast cell genes, that may become inactivated in the malignant counterparts. Using an immune-tolerization/immunization procedure of generating antibody, two different cell-surface glycoproteins termed luminal epithelial antigen, LEA.92 and LEA.135 were identified. LEA.92 and LEA.135 expressions on MEC in a culture model-system, that reflect various steps of neoplastic transformation were detected on normal or immortalized MEC lines that were non-tumorigenic in nude mice. Furthermore, no rearrangement of chromosome 1 was observed in those cells. In contrast, both glycoproteins were undetectable on oncogenically transformed or established lines of mammary carcinoma cells that were tumorigenic. LEA.92 or LEA.135 negative cell lines exhibited a partial deletion of their chromosome 1. In tissue sections, LEA.92 expression was detected on the apical plasma membrane of normal and hyperplastic but not on the malignant mammary or extramammary epithelial cells (MEC). However, unlike LEA.92, LEA.135 was detected on certain cases of primary breast carcinoma cells, irrespective of morphological differentiation, in tissue sections.