Synergistic antitumor effects of a combination of interferons and retinoic acid on human tumor cells in vitro and in vivo

Published on Monday, 16 May 2016


Solid tumors are relatively resistant to growth inhibition by IFNs. To enhance sensitivity, we assessed combinations of IFNs with all-trans-retinoic acid (RA).

Antiproliferative studies in vitro suggested that the growth of three human breast carcinomas (MCF-7, MDA-MB-231, and MDA-MB-468), an ovarian carcinoma (NIH-OVCAR-3), and a malignant melanoma (SK-MEL-1) was inhibited to a greater degree by combination treatment with human IFN-beta and RA compared to single agents.

Some of these cell lines were resistant to 10-100 IU/ml human IFN-alpha2b or IFN-beta or to 0.1-1.0 microM RA. Growth was inhibited significantly by combinations of IFNs and RA in all cell lines tested, and in some cases, cytotoxicity was observed.

Sequential treatment of MCF-7 cells with RA followed by IFN-beta was more effective at inhibiting growth than treatment with IFN-beta followed by RA, suggesting that RA modulated the anticellular response of IFN-beta rather than the converse.

In nude mice, the growth of MCF-7 and NIH-OVCAR-3 tumors was suppressed completely when combination treatment was started 2 days after tumor inoculation.

Established, 6-week-old NIH-OVCAR-3 tumors underwent regression when treated with the combination of IFN-beta and RA but not with single-agent therapy.

Together with our recent studies that demonstrated enhancement of IFN-stimulated gene expression by RA pretreatment in IFN-resistant cells, these data suggest that combination treatment with RA and IFNs may increase IFN-stimulated gene expression in IFN-resistant tumors, leading to augmented antitumor effects.



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See also:

- All-Trans-Retinoic Acid (ATRA - analogues and/or derivatives);

- Solution of retinoids in vitamin E in the Di Bella Method biological multitherapy;

- Evaluation of the safety and efficacy of the first-line treatment with somatostatin combined with melatonin, retinoids, vitamin D3, and low doses of cyclophosphamide in 20 cases of breast cancer: a preliminary report;

- The Di Bella Method (DBM) improved survival, objective response and performance status in a retrospective observational clinical study on 122 cases of breast cancer;

- Complete objective response to biological therapy of plurifocal breast carcinoma.