Tamoxifen in combination tranilast affects transforming growth factor-β ligands and its receptors in MCF-7 cells

Background: Worldwide, breast cancer is a major cancer leading in both incidence and mortality in women. The transforming growth factor-β (TGF-β) signaling network plays a complex role in regulating breast cancer. Tamoxifen is an anti-estrogen widely used for the treatment or prevention of breast cancer. TAM resistance is a problem in the management of breast cancer patients. Researches show that combination of tamoxifen with other substance that helps to overcome on resistance to tamoxifen. For this purpose, tranilast an anti-allergic compound that inhibits TGF-β and antagonizes the effects of its which has been reported to reduce the metastasis of some cancers applied.Since tranilast functions through TGF-β pathway, it seems also tamoxifen affects this signaling pathway, we hypothesize that combination of these drugs may a suitable option for breast cancer treatment. This study aimed to investigate the effect of tranilast and/or tamoxifen on TGF-β and metastasis resulting from TGF-β in breast cancer invitro. Methods: MCF-7 human breast cancer cell line were treated with different doses of tamoxifen and tranilast in combination or alone. Tamoxifen and tranilast was used in different concentrations (TAM: 1, 2, 5, 10 and 20 μM; tranilast: 10, 20, 50, 100 and 200 μM) as a single treatment and the combined treatments used were: 2 μM of tamoxifen with 5 different dose of tranilast for 48h. Proliferation inhibition was assessed by MTT assay. We examined the effects of tranilast and/or tamoxifen on TGF-β1, 2 and 3 or three surface receptors TGF-βRI, II and III mRNA expression as a potential targets for both tamoxifen and tranilast using real-time RT-PCR. Inhibitory effect of these drugs on invasion and metastasis were tested by matrigel invasion assay. Results: In the present study, we show that tamoxifen and tranilast as a single or in combination inhibit the growth and proliferation of MCF-7 human breast cancer cells in a dose-dependent manner. Tranilast as a single or in combination with tamoxifen can regulate TGF-β isoforms and receptors gene expression from human breast cancer cells. In addition, we demonstrate that tranilast and/or tamoxifen inhibit migration and invasion of MCF-7 cells and these results could explain the beneficial effects of combination tranilast and tamoxifen in management and treatment of breast cancer. We found that the inhibiting expression of TGF-β contributes to the loss ability of the breast tumor cells to invade in vitro. Conclusion: Tranilast induced synergistic effect with tamoxifen on breast cancer cells and could be a candidate drug for the treatment of breast cancer patients in all stages.

Keywords:

Breast cancer , Tamoxifen , Tranilast , Metastasis , Transforming growth factor-beta