GPR119 agonist enhances gefitinib responsiveness through lactate-mediated inhibition of autophagy

Ji Hye Im,Song-Yi Choi,Sun Young Kim,Byung Hwa Jeong,Jin-Sun Lee,Yoon Gyoon Kim,Yong Jin An,Keon Wook Kang,Sunghyouk Park

doi:10.1186/s13046-018-0949-2

Abstract

BackgroundLigand-dependent activation of the G-protein coupled receptor 119 (GPR119) lowers blood glucose via glucose-dependent insulin secretion and intestinal glucagon-like peptide-1 production. However, the function of GPR119 in cancer cells has not been studied.MethodsGPR119 expression was assessed by real-time qPCR and immunohistochemistry in human breast cancer cell lines and breast cancer tissues. Cell proliferation and cell cycle analyses were performed by Incucyte® live cell analysis system and flow cutometry, respectively. Autophagy activity was estimeated by western blottings and LC3-GFP transfection.ResultsmRNA or protein expression of GPR119 was detected in 9 cancer cell lines and 19 tissue samples. Cotreatment with GPR119 agonist (MBX-2982 or GSK1292263) significantly potentiated gefitinib-induced cell growth inhibition in gefitinib-insensitive MCF-7 and MDA-MB-231 breast cancer cells. We observed that caspase-3/7 activity was enhanced with the downregulation of Bcl-2 in MCF-7 cells exposed to MBX-2982. Gefitinib-induced autophagy is related with cancer cell survival and chemoresistance. GPR119 agonists inhibit gefitinib-induced autophagosome formation in MCF-7 and MDA-MB-231 cells. MBX-2982 also caused a metabolic shift to enhanced glycolysis accompanied by reduced mitochondrial oxidative phosphorylation. MBX-2982 increased intracellular (~ 2.5 mM) and extracellular lactate (~ 20 mM) content. Gefitinib-mediated autophagy was suppressed by 20 mM lactate in MCF-7 cells.ConclusionsGPR119 agonists reduced mitochondrial OXPHOS and stimulated glycolysis in breast cancer cells, with consequent overproduction of lactate that inhibited autophagosome formation. Because autophagy is crucial for the survival of cancer cells exposed to TKIs, GPR119 agonists potentiated the anticancer effects of TKIs.

Highlights

Ligand-dependent activation of the G-protein coupled receptor 119 (GPR119) lowers blood glucose via glucose-dependent insulin secretion and intestinal glucagon-like peptide-1 production
Compared to MCF-10A, GPR119 mRNA was amplified in seven breast cancer cell lines, and there were no correlation between existence of hormone receptors or Her2 and GPR119 exprtession (Fig. 1b)
Metabolic shift by MBX-2982 and inhibition of gefitinib-induced autophagy by lactate We previously reported that MBX-2982 activated AMP-activated protein kinase (AMPK), and pleiotrophic roles of AMPK have been investigated in many types of cancer [22, 29]

Summary

Introduction

Ligand-dependent activation of the G-protein coupled receptor 119 (GPR119) lowers blood glucose via glucose-dependent insulin secretion and intestinal glucagon-like peptide-1 production. The function of GPR119 in cancer cells has not been studied. EGFR-tyrosine kinase inhibitor (TKI) alone or in combination therapy with paclitaxel or docetaxel had been used for breast cancer patients in clinical trials, but both therapies failed [2]. It may be necessary to investigate the chemoresistance mechanism(s) to EGFR TKI for breast cancer patients. The effect of autophagy activation on a cancer cell survival is controversial. An mTOR inhibitor, induces autophagic cell death in MG63 osteosarcoma cells [6]. Autophagy is actively involved in cancer cell resistance to

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