Binding of retinoids to human breast cancer cell lines and their effects on cell growth

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Published on Thursday, 06 April 2017

Abstract

Vitamin A and its analogues (retinoids) regulate the differentiation of epithelial tissues.

Retinoids inhibit the induction of rat mammary cancers by carcinogens in vivo, and cellular binding proteins for retinoids have been demonstrated in some human breast cancer samples.

In this study, we examined the model system of human breast cancer cell lines in long-term tissue culture for effects of retinoids on growth and for the presence of cellular retinoid binding proteins.

Retinoic acid and retinol inhibit the growth of of MCF-7, Hs578T, and ZR-75-B cell lines.

Retinoic acid is more potent than retinol in this regard: 50% growth inhibition is achieved by 6 nM retinoic acid in ZR-75-B and by 700 nM in MCF-7 and Hs578T, whereas 5-8 muM retinol is required in all three cell lines. The time to onset of growth inhibition varies markedly between cell lines and is not related to cell density or doubling time. Retinoic acid increases the doubling time of MCF-7 and ZR-75-B by two- to threefold, but causes cell death in Hs578T. The growth inhibition is reversible in every cell line by removal of retinoic acid.

Specific and distinct binding of [(3)H]retinoic acid and [(3)H]retinol is present in cytosols of MCF-7 and Hs578T cells as assessed by sucrose density gradient centrifugation. In ZR-75-B, [(3)H]retinoic acid binding was present, but no binding of [(3)H]retinol was detectable.

This study reveals that retinoids may play an important role in the regulation and treatment of human breast cancer and that human breast cancer cell lines represent a useful model to study this role.

 

 

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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 melatonisn, 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.