A new human breast cancer cell line, KPL-1 secretes tumour-associated antigens and grows rapidly in female athymic nude mice.

We recently established a new human breast cell line, designated KPL-1, which was derived from the malignant effusion of a patient with breast cancer. This cell line is highly tumorigenic and grows rapidly in female nude mice. Cytogenetic analysis indicated its human origin and revealed a hypertriploid modal number of chromosomes. Electron microscopic examination suggested that the KPL-1 cells are of epithelial origin. Immunohistochemical studies revealed that the cells express cytokeratin, carcinoembryonic antigen and CA 15-3. They also possess a large number of oestrogen receptors but not progesterone receptors. Interestingly, KPL-1 cells seem to grow oestrogen independently in vitro. No amplification of c-erbB-2, c-myc, H-ras and N-ras genes was detected. KPL-1 cells secrete a large amount of tissue polypeptide antigen (TPA). Although the secretion of CA 15-3 seemed to be constant throughout all cell growth phases, TPA secretion increased during the exponential growth phase and decreased during the plateau phase. Serum TPA levels significantly correlated with the volume of KPL-1 tumours transplanted into nude mice. These data suggest that this KPL-1 cell line may be useful for studying oestrogen-independent growth and the kinetics of tumour-associated antigens in vivo as well as in vitro.