TITLE:
Long-Term Metformin Effect on Endometrial Cancer Development Depending on Glucose Environment In Vitro
AUTHORS:
Amanda Machado Weber, Carsten Lange, Julia Jauckus, Thomas Strowitzki, Ariane Germeyer
KEYWORDS:
Metformin, Endometrial Cancer, Proliferation, Migration, Clonogenicity
JOURNAL NAME:
Open Journal of Obstetrics and Gynecology,
Vol.11 No.9,
September
16,
2021
ABSTRACT: Objectives:Hyperinsulinemia as well as prolonged and elevated estrogen exposure are
considered as risk factors for endometrial cancer (EC) development. Metformin, an anti-hyperglycemic and
insulin-sensitizing biguanide, displayed anti-proliferative effects in recent
studies. In the present study, the effects of long-term
exposure of endometrial cancer cells to low and moderate concentrations of
metformin on cell viability, proliferation, clonogenicity and migration were
investigated under different metabolic conditions. Study Design: EC cell lines HEC-1A and Ishikawa were cultured
under normo- (NG, 5.5
mM) or hyperglycemic (HG, 17.0 mM) conditions and treated with metformin (0.01 - 5.0 mM) in the presence of β-estradiol (E2) for 7 d. Results: A concentration-dependent decrease of cellular
viability was observed in the MTT and ATP assays after metformin treatment. IC50 values were between 0.7 - 3.7 mM (NG) and 3.0 - 18.3 mM (HG), respectively. A protective effect of glucose on cellular
viability was detected only in the ATP assay. Furthermore, metformin (0.5 - 5.0 mM) led to a significant decrease in
proliferation by 12% - 55% (NG). However, a decreased proliferation rate was only induced at 5.0
mM metformin (40%) in the presence of high glucose levels in HEC-1A cells,
indicating a glucose-related resistance to anti-proliferative metformin
effects, which—to a lesser extent—was also observed in Ishikawa cells.
Metformin treatment also caused concentration-dependent effects on
clonogenicity and decreased the number and size of colonies. In HEC-1A cells,
metformin (0.5 - 5.0 mM) reduced the colony formation by 44% - 80% (NG) and 29% - 81% (HG), respectively. Slightly higher metformin
concentrations (1.0 - 5.0 mM)
were necessary in Ishikawa cells to reduce clonogenicity by 36% - 86% independent of glucose levels. An investigation of migration in the
wound healing assay revealed that the % wound closure decreased with increasing
metformin concentrations, but independent of glucose levels. After treatment
with 5.0 mM metformin, migration was significantly reduced in both cell lines. Conclusion: Our in vitro findings support the
hypothesis that metformin has a direct effect on endometrial cancer cell lines
and reflects the importance of the local glucose environment, suggesting that
metformin may be considered as a potential adjuvant agent in endometrial cancer
therapy due to its direct and indirect effects on endometrial development. However,
further studies are necessary that confirm the relevance of our data for
clinical applications.