Cited by 46Metabolism, Diabetes, and CancerDrug Transport and Resistance MechanismsPI3K/AKT/mTOR signaling in cancer

Cation-selective transporters are critical to the AMPK-mediated antiproliferative effects of metformin in human breast cancer cells: Transporters in metformin effect against breast cancer cells

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Cai, Hao, Zhang, Yunhui, Han, Tianxiang Kevin, Everett, Ruth S., Thakker, Dhiren R.·2016·International Journal of Cancer

Abstract

The antidiabetic drug metformin exerts antineoplastic effects against breast cancer and other cancers. One mechanism by which metformin is believed to exert its anticancer effect involves activation of its intracellular target, adenosine monophosphate-activated protein kinase (AMPK), which is also implicated in the antidiabetic effect of metformin. It is proposed that in cancer cells, AMPK activation leads to inhibition of the mammalian target of rapamycin (mTOR) and the downstream pS6K that regulates cell proliferation. Due to its hydrophilic and cationic nature, metformin requires cation-selective transporters to enter cells and activate AMPK. This study demonstrates that expression levels of cation-selective transporters correlate with the antiproliferative and antitumor efficacy of metformin in breast cancer. Metformin uptake and antiproliferative activity were compared between a cation-selective transporter-deficient human breast cancer cell line, BT-20, and a BT-20 cell line that was engineered to overexpress organic cation transporter 3 (OCT3), a representative of cation-selective transporters and a predominant transporter in human breast tumors. Metformin uptake was minimal in BT-20 cells, but increased by >13-fold in OCT3-BT20 cells, and its antiproliferative potency was >4-fold in OCT3-BT20 versus BT-20 cells. This increase in antiproliferative activity was associated with greater AMPK phosphorylation and decreased pS6K phosphorylation in OCT3-BT20 cells. In vitro data were corroborated by in vivo observations of significantly greater antitumor efficacy of metformin in xenograft mice bearing OCT3-overexpressing tumors versus low transporter-expressing wildtype tumors. Collectively, these findings establish a clear relationship between cation-selective transporter expression, the AMPK-mTOR-pS6K signaling cascade, and the antiproliferative activity of metformin in breast cancer.

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  • [14C]-Metformin uptake was 13 times higher in OCT3-BT20 cells than in BT-20 cells, and associated with increased AMPK phosphorylation and decreased pS6K phosphorylation in OCT3-BT20 cells, and these results were substantiated in mice with OCT3 overexpressing tumors.

    “[14C]-Metformin uptake was 13 times higher in OCT3-BT20 cells than in BT-20 cells, and associated with increased AMPK phosphorylation and decreased pS6K phosphorylation in OCT3-BT20 cells and these results were substantiated in mice with OCT3 overexpressing tumors (241).”
  • A logical target whereby metformin could mediate its putative antiproliferative effects in cancer is via inhibition of mTOR and pS6K, either via activation of AMPK or via an AMPK-independent pathway.

    “A logical target whereby metformin could mediate its putative antiproliferative effects in cancer is via inhibition of mTOR and the serine-threonine kinase, ribosomal S6K (pS6K), either via activation of AMPK or via an AMPK-independent pathway (241, 242).”

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Research works printed but not linked: 4

  1. V C 2015 UICC 10970215, 2016, 9, Transporters in metformin effect against breast cancer cells Int. J. Cancer: 138, 2281-2292 (2016) · DOI
  2. V C 2015 UICC 10970215, 2016, 9, · DOI
  3. V C 2015 UICC 10970215, 2016, 9, uptake and accumulation of metformin in caco-2 cell monolayers. J Pharmacol Exp Ther 2015; 352: 519-28. · DOI
  4. Segal ED, Yasmeen A, Beauchamp MC, et al. Relevance of theOCT1 transporter to the antineo- plastic effect of biguanides. Biochem Biophys Res Commun 2011; 414:694-9.

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Authors
Cai, H., Zhang, Y., Han, T. K., Everett, R. S., & Thakker, D. R.
Affiliations
University of North Carolina at Chapel Hill (US)
Corresponding author
Thakker, Dhiren R.
Venue
International Journal of Cancer
Publisher
Wiley
Published
2016-01-08
Volume
138
Issue
9
Pages
2281-2292
ISSN
0020-7136 (ISSN-L)
OpenAlex
W2220293484
Cited by
46
References
47
Citations by year
2026: 1 · 2025: 2 · 2024: 4 · 2023: 1 · 2022: 5 · 2021: 8 · 2020: 6 · 2019: 10 · 2018: 2 · 2017: 6 · 2016: 1
FWCI
1.30
Type
journal article
Language
en
Open access
Locations
  • International Journal of Cancer (publishedVersion)
  • PubMed (publishedVersion)
Funders
North Carolina Translational Clinical Research Sciences Institute
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Metabolism, Diabetes, and Cancer
  • Health Sciences › Medicine › Oncology › Drug Transport and Resistance Mechanisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › PI3K/AKT/mTOR signaling in cancer
Keywords
metformin, OCT3, breast cancer, AMPK activation, mTOR signaling, drug uptake, antiproliferative activity, anticancer drug repurposing, tumor xenografts
MeSH terms
Organic Cation Transporter 3, Animals, Antineoplastic Agents, Breast Neoplasms, Female, Mammary Neoplasms, Experimental, Metformin, Mice, Nude, Signal Transduction, Xenograft Model Antitumor Assays, Organic Cation Transport Proteins, Ribosomal Protein S6 Kinases, 70-kDa, Cell Line, Tumor, Cell Proliferation, Mice, AMP-Activated Protein Kinases, TOR Serine-Threonine Kinases

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