Hyper-O-GlcNAcylation induces cisplatin resistance via regulation of p53 and c-Myc in human lung carcinoma

Sudjit Luanpitpong,Nawin Chanthra,Surapol Issaragrisil,Paweorn Angsutararux,Parinya Samart,Pithi Chanvorachote

doi:10.1038/s41598-017-10886-x

Abstract

Aberrant metabolism in hexosamine biosynthetic pathway (HBP) has been observed in several cancers, affecting cellular signaling and tumor progression. However, the role of O-GlcNAcylation, a post-translational modification through HBP flux, in apoptosis remains unclear. Here, we found that hyper-O-GlcNAcylation in lung carcinoma cells by O-GlcNAcase inhibition renders the cells to apoptosis resistance to cisplatin (CDDP). Profiling of various key regulatory proteins revealed an implication of either p53 or c-Myc in the apoptosis regulation by O-GlcNAcylation, independent of p53 status. Using co-immunoprecipitation and correlation analyses, we found that O-GlcNAcylation of p53 under certain cellular contexts, i.e. high p53 activation, promotes its ubiquitin-mediated proteasomal degradation, resulting in a gain of oncogenic and anti-apoptotic functions. By contrast, O-GlcNAcylation of c-Myc inhibits its ubiquitination and subsequent proteasomal degradation. Gene manipulation studies revealed that O-GlcNAcylation of p53/c-Myc is in part a regulator of CDDP-induced apoptosis. Accordingly, we classified CDDP resistance by hyper-O-GlcNAcylation in lung carcinoma cells as either p53 or c-Myc dependence based on their molecular targets. Together, our findings provide novel mechanisms for the regulation of lung cancer cell apoptosis that could be important in understanding clinical drug resistance and suggest O-GlcNAcylation as a potential target for cancer therapy.

Highlights

Cancer cells increase nutrient consumption leading to deregulating cellular metabolism, an emerging characteristic hallmark of cancer[1, 2]
The present study identifies the previously unknown role of hyper-O-GlcNAcylation in lung carcinoma cells in regulating a distinct set of target proteins that involve in apoptosis resistance to CDDP, the frontline chemotherapy for both non-small cell lung carcinoma (NSCLC) and small cell lung carcinoma (SCLC)[28, 29]
Reprogramming in glucose metabolism and energy production in cancers has been substantiated for decades, known as the Warburg effect, in which cancer cells increase glucose uptake and rely preferentially on aerobic glycolysis instead of oxidative phosphorylation for ATP production, even under normoxic conditions[30, 31]

Summary

Introduction

Cancer cells increase nutrient consumption leading to deregulating cellular metabolism, an emerging characteristic hallmark of cancer[1, 2]. O-linked-β-N-acetylglucosomaine (O-GlcNAc) is subsequently transferred from UDP-GlcNAc to serine (Ser) and/or threonine (Thr) residues in substrate proteins by the enzyme O-GlcNAc transferase (OGT) causing a post-translational modification (PTM) called O-GlcNAcylation. This PTM which can be removed by the enzyme O-GlcNAcase (OGA; encoded by MGEA5) can alter protein functions and stability directly and indirectly, e.g. by competing with phosphorylation sites. We present evidence that hyper-O-GlcNAcylation by OGA inhibitors renders human lung carcinoma cells to apoptosis resistance induced by cisplatin (CDDP) via two distinct pathways that are either p53- or c-Myc-dependent, depending on cellular context, independent of p53 status. Our findings unveil a previously unknown mechanism for the regulation of lung tumor cell apoptosis that could be important in understanding clinical drug resistance and may have clinical utility for targeted drug therapy of lung and other cancers whose etiology is dependent on O-GlcNAcylation

Methods

Results

Conclusion