Melatonin suppression of aerobic glycolysis (Warburg effect), survival signalling and metastasis in human leiomyosarcoma

J Pineal Res. 2016 Mar;60(2):167-77. doi: 10.1111/jpi.12298. Epub  2015 Dec 23.
Melatonin suppression of aerobic glycolysis (Warburg effect), survival signalling and metastasis in human leiomyosarcoma.

1Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA.
2Tulane Cancer Center and Louisiana Cancer Research Consortium, New Orleans, LA, USA.
3Tulane Center for Circadian Biology, Tulane University School of Medicine, New Orleans, LA, USA.
4Department of Surgery, Tulane University School of Medicine, New Orleans, LA, USA.

Abstract

Leiomyosarcoma (LMS) represents a highly malignant, rare soft tissue sarcoma with high rates of morbidity and mortality. Previously, we demonstrated that tissue-isolated human LMS xenografts perfused in situ are highly sensitive to the direct anticancer effects of physiological nocturnal blood levels of melatonin which inhibited tumour cell proliferative activity, linoleic acid (LA) uptake and metabolism to 13-hydroxyoctadecadienoic acid (13-HODE). Here, we show the effects of low pharmacological blood concentrations of melatonin following oral ingestion of a melatonin supplement by healthy adult human female subjects on tumour proliferative activity, aerobic glycolysis (Warburg effect) and LA metabolic signalling in tissue-isolated LMS xenografts perfused in situ with this blood. Melatonin markedly suppressed aerobic glycolysis and induced a complete inhibition of tumour LA uptake, 13-HODE release, as well as significant reductions in tumour cAMP levels, DNA content and [(3) H]-thymidine incorporation into DNA. Furthermore, melatonin completely suppressed the phospho-activation of ERK 1/2, AKT, GSK3β and NF-kB (p65). The addition of S20928, a nonselective melatonin antagonist, reversed these melatonin inhibitory effects. Moreover, in in vitro cell culture studies, physiological concentrations of melatonin repressed cell proliferation and cell invasion. These results demonstrate that nocturnal melatonin directly inhibited tumour growth and invasion of human LMS via suppression of the Warburg effect, LA uptake and other related signalling mechanisms. An understanding of these novel signalling pathway(s) and their association with aerobic glycolysis and LA metabolism in human LMS may lead to new circadian-based therapies for the prevention and treatment of LMS and potentially other mesenchymally derived solid tumours.
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

KEYWORDS:
Warburg effect; leiomyosarcoma; melatonin; metastasis; signalling pathways

PMID:

26607298

Metformin is synthetically lethal with glucose withdrawal in cancer cells

Cell Cycle. 2012 Aug 1;11(15):2782-92. doi: 10.4161/cc.20948. Epub  2012 Aug 1.
Metformin is synthetically lethal with glucose withdrawal in cancer cells.
Menendez JA1, Oliveras-Ferraros C, Cufí S, Corominas-Faja B, Joven J, Martin-Castillo B, Vazquez-Martin A.

Author information

1Translational Research Laboratory, Catalan Institute of Oncology, Girona, Catalonia, Spain. jmenendez@iconcologia.net

Abstract

Glucose deprivation is a distinctive feature of the tumor microecosystem caused by the imbalance between poor supply and an extraordinarily high consumption rate. The metabolic reprogramming from mitochondrial respiration to aerobic glycolysis in cancer cells (the “Warburg effect”) is linked to oncogenic transformation in a manner that frequently implies the inactivation of metabolic checkpoints such as the energy rheostat AMP-activated protein kinase (AMPK). Because the concept of synthetic lethality in oncology can be applied not only to genetic and epigenetic intrinsic differences between normal and cancer cells but also to extrinsic ones such as altered microenvironment, we recently hypothesized that stress-energy mimickers such as the AMPK agonist metformin should produce metabolic synthetic lethality in a glucose-starved cell culture milieu imitating the adverse tumor growth conditions in vivo. Under standard high-glucose conditions, metformin supplementation mostly caused cell cycle arrest without signs of apoptotic cell death. Under glucose withdrawal stress, metformin supplementation circumvented the ability of oncogenes (e.g., HER2) to protect breast cancer cells from glucose-deprivation apoptosis. Significantly, representative cell models of breast cancer heterogeneity underwent massive apoptosis (by >90% in some cases) when glucose-starved cell cultures were supplemented with metformin. Our current findings may uncover crucial issues regarding the cell-autonomous metformin’s anti-cancer actions: (1) The offently claimed clinically irrelevant, non-physiological concentrations needed to observe the metformin’s anti-cancer effects in vitro merely underlie the artifactual interference of erroneous glucose-rich experimental conditions that poorly reflect glucose-starved in vivo conditions; (2) the preferential killing of cancer stem cells (CSC) by metformin may simply expose the best-case scenario for its synthetically lethal activity because an increased dependency on Warburg-like aerobic glycolysis (hyperglycolytic phenotype) is critical to sustain CSC stemness and immortality; (3) the microenvironment-mediated contextual synthetic lethality of metformin should be expected to enormously potentiate the anti-cancer effect of anti-angiogenesis agents that promote severe oxygen and glucose deprivation in certain areas of the tumor tissues.

Comment in

Metformin is synthetically lethal with glucose withdrawal in cancer cells. [Cell Cycle.  2012]
“Double hit” makes the difference. [Cell Cycle.  2012]

PMID:

22809961

[PubMed – indexed for MEDLINE]