Interferon treatment of human stomach and breast carcinoma xenografts in nude mice

Antiproliferative effects of natural interferon beta alone and in combination with natural interferon gamma on human breast carcinomas in nude mice

Nude mice bearing bilateral xenografts of human breast carcinoma cells (MCF-7 and BT20) were treated with 2 or 45-day cycles of intralesional (i.l.) injections of human natural interferon beta (nIFN-beta) alone or in combination with human natural interferon gamma (nIFN-gamma). The injections were administered to only 1 of the 2 tumors in each animal, thus making it possible to assess at the same time local therapeutic effects in the injected tumors and systemic effects in the contralateral ones. When n-IFN-beta was used as a single agent only mild local antitumor effects and virtually no systemic effects were observed. In contrast, the combined administration of nIFN-beta/nIFN-gamma produced marked antiproliferative effects, presumably as a result of the synergistic action of type I and type II IFNs. These effects ranged from complete regression documented histologically in 2 MCF-7 tumors to varying degrees of growth inhibition with persistence of residual microscopic or grossly detectable tumor. Local effects were more pronounced than systemic effects. The therapeutic efficacy of nIFN-beta proved to be greater than that of recombinant interferon beta (rIFN-beta). In MCF-7 tumors nIFN-beta appeared to be less effective than nIFN-alpha, whereas the opposite was true for BT20 tumors.

Inhibition of hormone-dependent and independent breast cancer cell growth in vivo and in vitro with the antiestrogen toremifene and recombinant human interferon-alpha 2

The antiproliferative action of the antiestrogen toremifene and recombinant human interferon-alpha 2a (IFN-alpha 2a) were examined on human breast cancer cell lines grown in culture and in the athymic mouse. Solid tumors grew from an inoculation of a 99:1 ratio of hormone dependent (MCF-7) and hormone independent (MDA-MB-231) breast cancer cells without estrogen administration. However, estradiol supplementation significantly increased the rate of tumor growth. The daily administration of 1.35 x 10(6) U of recombinant human IFN-alpha 2a resulted in a marked rduction of tumor growth in both estradiol-treated and non-treated mice. Toremifene administration (130 micrograms/day from a sustained release preparation) markedly inhibited estradiol stimulation of mouse uterine weight and partially reduced estradiol-stimulated tumor growth. The combination of IFN-alpha 2a (1.35 x 10(6) u/day) with toremifene (130 micrograms/day) reduced estradiol-stimulated growth much below that of toremifene alone but not below that seen with interferon alone. Toremifene (10(-10)-10(-6) M) did not inhibit the growth of hormone-independent MDA-MB-231 breast cancer cells in vitro whereas it did inhibit the growth of hormone-dependent MCF-7 cells in phenol red containing media. IFN-alpha 2a (1-10,000 u) inhibited the growth of both MCF-7 and MDA-MB-231 cells in culture; however, MCF-7 cells were approximately 10-fold more sensitive to interferon inhibition. This was consistent with the MCF-7 cells showing a greater sensitivity to interferon than MDA-MB-231 cells in the induction of 2'5'-oligoadenylate synthetase.(ABSTRACT TRUNCATED AT 250 WORDS)