Dual effect of metformin on growth inhibition and oestradiol production in breast cancer cells

  • Authors:
    • S. Rice
    • L. Pellat
    • A. Ahmetaga
    • G. Bano
    • H. D. Mason
    • S. A. Whitehead
  • View Affiliations

  • Published online on: February 25, 2015     https://doi.org/10.3892/ijmm.2015.2108
  • Pages: 1088-1094
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Abstract

Evidence has been accumulating for a role for metformin in reducing breast cancer risk in post-menopausal women. It inhibits growth of breast cancer cells via several mechanisms, primarily the AMPK/mTOR signalling pathway. Another possible protective mechanism may be the ability of metformin to inhibit aromatase activity. In the present study, we investigated the effects of metformin on the basal growth of MCF-7 cells, after oestradiol (E2) stimulation and after the inhibition of mTOR by rapamycin. Secondly, we investigated the effects of metformin on the activity of a number of steroidogenic enzymes and the mRNA expression of aromatase and steroid sulphatase (STS). High doses of metformin significantly inhibited both basal and oestrogen‑stimulated cell division. Low-dose rapamycin (10-10 M) did not inhibit growth, but the addition of metformin induced a significant reduction in growth. High-dose rapamycin (10-8 M) inhibited growth, and this was further attenuated by the addition of metformin. Exposure to low (10-7 M) and high (10-4 M) doses of metformin for 7-10 days significantly reduced the conversion of androstenedione (ANDRO) and testosterone (TESTO) (both requiring aromatase), but not the conversion of oestrone or oestrone sulphate (ES) via 17β-hydroxysteroid dehydrogenase/sulphatase to E2. This attenuation was via a downregulation in the expression of total aromatase mRNA and promoter II, whilst the expression of sulphatase was unaffected by metformin. In conclusion, plasma levels of metformin have a dual therapeutic action, first by directly inhibiting cell proliferation which can be augmented by rapamycin analogues, and secondly, by inhibiting aromatase activity and reducing the local conversion of androgens to E2.
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April-2015
Volume 35 Issue 4

Print ISSN: 1107-3756
Online ISSN:1791-244X

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Spandidos Publications style
Rice S, Pellat L, Ahmetaga A, Bano G, Mason HD and Whitehead SA: Dual effect of metformin on growth inhibition and oestradiol production in breast cancer cells. Int J Mol Med 35: 1088-1094, 2015
APA
Rice, S., Pellat, L., Ahmetaga, A., Bano, G., Mason, H.D., & Whitehead, S.A. (2015). Dual effect of metformin on growth inhibition and oestradiol production in breast cancer cells. International Journal of Molecular Medicine, 35, 1088-1094. https://doi.org/10.3892/ijmm.2015.2108
MLA
Rice, S., Pellat, L., Ahmetaga, A., Bano, G., Mason, H. D., Whitehead, S. A."Dual effect of metformin on growth inhibition and oestradiol production in breast cancer cells". International Journal of Molecular Medicine 35.4 (2015): 1088-1094.
Chicago
Rice, S., Pellat, L., Ahmetaga, A., Bano, G., Mason, H. D., Whitehead, S. A."Dual effect of metformin on growth inhibition and oestradiol production in breast cancer cells". International Journal of Molecular Medicine 35, no. 4 (2015): 1088-1094. https://doi.org/10.3892/ijmm.2015.2108