Elsevier

Gynecologic Oncology

Volume 110, Issue 2, August 2008, Pages 246-250
Gynecologic Oncology

In vitro metformin anti-neoplastic activity in epithelial ovarian cancer

https://doi.org/10.1016/j.ygyno.2008.04.008 Get rights and content

Abstract

Objective

Metformin, a commonly used drug in the treatment of type II diabetes, may reduce cancer risk and improve cancer prognosis. We evaluated its effect on epithelial ovarian cancer cell lines.

Methods

The OVCAR-3 and OVCAR-4 cell lines were exposed to metformin with and without cisplatin. Cytotoxicity assays were performed in triplicates using the Alamar colorimetric assay. Levels of total and phosphorylated AMPK, p70S6K and S6K were evaluated by Western blotting following exposure to metformin.

Results

Metformin induces dose- and time-dependent growth inhibition of OVCAR-3 and OVCAR-4 cell lines. Metformin potentiated the effect of cisplatin in vitro. Metformin growth inhibition was partly abolished by the AMPK inhibitor, compound C. Western blotting demonstrated that metformin at cytotoxic concentrations, induced AMPK phosphorylation and decreased p70S6K and S6K phosphorylation, suggesting the mechanism for its anti-proliferative action.

Conclusion

Metformin significantly inhibits the growth of ovarian cancer cell lines and potentiates cisplatin. Further pre-clinical studies are being conducted to determine the applicability of metformin in the treatment of ovarian cancer.

Introduction

Ovarian cancer is the fifth most common cause of cancer related mortality in western countries [1]. The most common type is of epithelial origin. Although the majority of patients have a satisfactory initial clinical response, more than 70% will experience recurrences and ultimately die of the disease [2]. New therapeutic modalities are therefore necessary to overcome the high recurrence rate and to change response to treatment into cure.

Increasing basic science evidence and dietary findings suggests that insulin and insulin-like growth factors (IGFs) play a role in carcinogenesis and disease progression in epithelial ovarian cancer [reviewed in [3], [4], [5], [6]]. Therefore downregulation of the IGF signaling pathway attained by “caloric restriction” has been postulated as a therapeutic approach to prevent cancer development [7], [8]. Among other effects, “caloric restriction” leads to the activation of the AMP-activated protein kinase (AMPK) which is the primary activator of cellular response to lowered ATP levels [9], [10]. Activated AMPK has been associated with growth inhibition of human cancer cell lines [11], [12].

Upon activation, the phosphorylated AMPK suppresses the mammalian target of Rapamycin (mTOR) signaling pathway, which, via its downstream molecular effectors 4E-BP1 and p70S6, ultimately affects cellular transcription and translation [13], [14]. Several experimental approaches have demonstrated the therapeutic potential of mTOR inhibition, inducing drastic anti-proliferative and anti-angiogenic effects in pre-clinical models [14], [15], [16], [17].

Metformin, a commonly used oral anti-hyperglycemic agent of the biguanide family, also activates AMPK [18]. Taken together with recent population-based studies that suggested that metformin may reduce cancer risk and improve prognosis [19], [20], we evaluated the in vitro anti-neoplastic activity of metformin in epithelial ovarian cancer, and its relationship to AMPK activation and downstream pathway.

Section snippets

Cell lines and treatments

The human ovarian cancer cell lines OVCAR-3 (American tissue culture collection, Manassas, VA) and OVCAR-4 were grown in RMPI-1640 supplemented with 10% fetal bovine serum (FBS), 2 mM l-glutamine, and 10 μg/ml of garamycin at 37 °C in 5% CO2. The cell cultures were routinely passaged every 3–5 days. Assays were conducted under serum-free conditions as previously described [3]. Metformin was obtained from Sigma Laboratories (Oakville, Ontario). Cisplatin was obtained from Mayne Pharmaceuticals

Metformin inhibits the proliferation of OVCAR-3 and OVCAR-4 cells in a dose- and time-dependent manner

Metformin induced significant proliferation inhibition on both the OVCAR-3 and OVCAR-4 cells lines in a dose- (Fig. 1) and time-dependent manner (Fig. 2).

Metformin potentiates the effect of cisplatin

Cisplatin remains the most active treatment for epithelial ovarian carcinoma, however sensitivity of the tumor cells to cisplatin varies. Here we demonstrate that metformin could increase the cytotoxicity of cisplatin on OVCAR-3 cells (Fig. 3).

Compound C inhibits the anti-proliferative effect induced by metformin

Compound C is known to function as an ATP-competitive inhibitor of AMPK [21]. Here we demonstrate

Discussion

The potential link between Insulin/IGF-I signaling pathways and cancer has attracted substantial attention during the last years [22]. As a result there is a growing interest in targeting this pathway for cancer treatment. AMPK is a conserved serine/threonine protein kinase regulator of cellular metabolism that is activated in response to nutrient deprivation and pathological stresses [23]. Interestingly, several in vitro and in vivo studies show cancer growth inhibition following AMPK

Conflict of interest statement

The authors declare that there are no conflicts of interest.

Acknowledgments

This work was in part supported by grants from the Israel Cancer Research Foundation, the Canadian Foundation for Women's Health, the Gloria Shapiro Foundation, Génome Québec, the Fonds de recherche en santé du Québec, the Norych Career Scientist Award, and the Schouella Distinguished Scientist Award.

References (31)

  • M.H. Zou et al.

    Activation of the AMP-activated protein kinase by the anti-diabetic drug metformin in vivo. Role of mitochondrial reactive nitrogen species

    J Biol Chem

    (2004)
  • A. Jemal et al.

    Cancer statistics, 2008

    CA Cancer J Clin

    (2008)
  • J.H. Silber et al.

    Does ovarian cancer treatment and survival differ by the specialty providing chemotherapy?

    J Clin Oncol

    (2007)
  • L. Lu et al.

    The relationship of insulin-like growth factor-II, insulin-like growth factor binding protein-3, and estrogen receptor-∝ expression to disease progression in epithelial ovarian cancer

    Clin cancer res

    (2006)
  • D. Spentzos et al.

    IGF axis gene expression patterns are prognostic of survival in epithelial ovarian cancer

    Endocr Relat Cancer

    (2007)
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