Isolation and characterization of a new human breast cancer cell line, KPL-4, expressing the Erb B family receptors and interleukin-6

A new human breast cancer cell line, KPL-4, was recently isolated from the malignant pleural effusion of a breast cancer patient with an inflammatory skin metastasis. This cell line can be cultured under serum-free conditions and is tumorigenic in female athymic nude mice. Flow cytometric analysis r evealed the expression of Erb B-1, -2 and -3. Dot blot hybridization showed a 15-fold amplification of the erb B-2. Reverse transcription-polymerase c hain reaction analysis showed a detectable level of mRNA expression of all the Erb B family receptors. in addition, all the receptors were autophospho rylated under a serum-supplemented condition. Unexpectedly, transplanted KP L-4 tumours induced cachexia of recipient mice. A high concentration of int erleukin-6 (IL-6) was detected in both the culture medium and the serum of mice. The weight of tumours significantly correlated with the serum IL-6 le vel. The antiproliferative effect of a humanized anti-Erb B-2 monoclonal an tibody, rhuMAbHER2, was investigated. This antibody significantly inhibited the growth of KPL-4 cells in vitro but modestly in vivo. Loss of mouse bod y weight was partly reversed by rhuMAbHER2. These findings suggest that KPL -4 cells may be useful in the development of new strategies against breast cancer overexpressing the Erb B family receptors and against IL-6-induced c achexia.