Florence Durieux

Methylglyoxal, a glycolysis side-product, induces Hsp90 glycation and YAP-mediated tumor growth and metastasis

Metabolic reprogramming toward aerobic glycolysis unavoidably induces methylglyoxal (MG) formation in cancer cells. MG mediates the glycation of proteins to form advanced glycation end products (AGEs). We have recently demonstrated that MG-induced AGEs are a common feature of breast cancer. Little is known regarding the impact of MG-mediated carbonyl stress on tumor progression. Breast tumors with MG stress presented with high nuclear YAP, a key transcriptional co-activator regulating tumor growth and invasion. Elevated MG levels resulted in sustained YAP nuclear localization/activity that could be reverted using Carnosine, a scavenger for MG. MG treatment affected Hsp90 chaperone activity and decreased its binding to LATS1, a key kinase of the Hippo pathway. Cancer cells with high MG stress showed enhanced growth and metastatic potential in vivo. These findings reinforce the cumulative evidence pointing to hyperglycemia as a risk factor for cancer incidence and bring renewed interest in MG scavengers for cancer treatment. DOI: http://dx.doi.org/10.7554/eLife.19375.001

Methylglyoxal-Mediated Stress Correlates with High Metabolic Activity and Promotes Tumor Growth in Colorectal Cancer

Cancer cells generally rely on aerobic glycolysis as a major source of energy. Methylglyoxal (MG), a dicarbonyl compound that is produced as a side product during glycolysis, is highly reactive and induces the formation of advanced glycation end-products that are implicated in several pathologies including cancer. All mammalian cells have an enzymatic defense against MG composed by glyoxalases GLO1 and GLO2 that converts MG to d-lactate. Colorectal cancer (CRC) is one of the most frequently occurring cancers with high morbidity and mortality. In this study, we used immunohistochemistry to examine the level of MG protein adducts, in a series of 102 CRC human tumors divided into four clinical stages. We consistently detected a high level of MG adducts and low GLO1 activity in high stage tumors compared to low stage ones suggesting a pro-tumor role for dicarbonyl stress. Accordingly, GLO1 depletion in CRC cells promoted tumor growth in vivo that was efficiently reversed using carnosine, a potent MG scavenger. Our study represents the first demonstration that MG adducts accumulation is a consistent feature of high stage CRC tumors. Our data point to MG production and detoxification levels as an important molecular link between exacerbated glycolytic activity and CRC progression.

Hormetic potential of methylglyoxal, a side-product of glycolysis, in switching tumours from growth to death

Metabolic reprogramming toward aerobic glycolysis unavoidably favours methylglyoxal (MG) and advanced glycation end products (AGEs) formation in cancer cells. MG was initially considered a highly cytotoxic molecule with potential anti-cancer value. However, we have recently demonstrated that MG enhanced tumour growth and metastasis. In an attempt to understand this dual role, we explored MG-mediated dicarbonyl stress status in four breast and glioblastoma cancer cell lines in relation with their glycolytic phenotype and MG detoxifying capacity. In glycolytic cancer cells cultured in high glucose, we observed a significant increase of the conversion of MG to D-lactate through the glyoxalase system. Moreover, upon exogenous MG challenge, glycolytic cells showed elevated amounts of intracellular MG and induced de novo GLO1 detoxifying enzyme and Nrf2 expression. Thus, supporting the adaptive nature of glycolytic cancer cells to MG dicarbonyl stress when compared to non-glycolytic ones. Finally and consistent with the pro-tumoural role of MG, we showed that low doses of MG induced AGEs formation and tumour growth in vivo, both of which can be reversed using a MG scavenger. Our study represents the first demonstration of a hormetic effect of MG defined by a low-dose stimulation and a high-dose inhibition of tumour growth.

Myoferlin controls mitochondrial structure and activity in pancreatic ductal adenocarcinoma, and affects tumor aggressiveness

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related death. Therapeutic options remain very limited and are based on classical chemotherapies. Energy metabolism reprogramming appears as an emerging hallmark of cancer and is considered a therapeutic target with considerable potential. Myoferlin, a ferlin family member protein overexpressed in PDAC, is involved in plasma membrane biology and has a tumor-promoting function. In the continuity of our previous studies, we investigated the role of myoferlin in the context of energy metabolism in PDAC. We used selected PDAC tumor samples and PDAC cell lines together with small interfering RNA technology to study the role of myoferlin in energetic metabolism. In PDAC patients, we showed that myoferlin expression is negatively correlated with overall survival and with glycolytic activity evaluated by 18F-deoxyglucose positron emission tomography. We found out that myoferlin is more abundant in lipogenic pancreatic cancer cell lines and is required to maintain a branched mitochondrial structure and a high oxidative phosphorylation activity. The observed mitochondrial fission induced by myoferlin depletion led to a decrease of cell proliferation, ATP production, and autophagy induction, thus indicating an essential role of myoferlin for PDAC cell fitness. The metabolic phenotype switch generated by myoferlin silencing could open up a new perspective in the development of therapeutic strategies, especially in the context of energy metabolism.

PO-225 Dual role of methylglyoxal, a glycolysis side-product, in cancer

Introduction Methylglyoxal (MG) is spontaneously produced during glycolysis. MG reacts with proteins, lipids and DNA, thus inducing a dicarbonyl stress. Glyoxalase 1 (GLO1) detoxifies MG into D-Lactate. High MG is notably associated with diabetes and cancer as the latter presents a deregulated energy metabolism where tumour cells use glycolysis rather than mitochondrial respiration. The impact of MG on cancer is ambiguous as some studies reported an anti-tumour and others a pro-tumour effect upon GLO1 silencing. Material and methods In this study, we aimed to evaluate the effect of MG stress on a panel of cancer cell lines: MDA-MB-231 known to be glycolytic and MCF7 cells known to be more oxidative breast cancer cells and U87-MG and U251 glioblastoma cell lines. We characterised glycolysis, MG production and detoxification under different conditions in these cell lines. U87-MG tumour growth upon MG treatment was evaluated using the chick chorioallantoic membrane tumour model (CAM). Results and discussions We observed that only MDA-MB-231 and U87-MG cell lines are able to increase their glycolysis flux upon glucose stimulation. In these conditions, both cell lines increased their MG production and detoxification via the glyoxalase system. Under exogenous MG treatment, both glycolytic cell lines showed increased expression of both NRF2 and its target gene GLO1, whereas no ROS accumulation was detected. Upon GLO1 activity inhibition, an alternative MG detoxification system, the aldo-keto reductase (AKR) enzymes, is significantly increased at least in U87-MG cells. Finally, U87-MG cells xenografted on CAM and treated with MG showed an increased growth at low MG doses while high doses reduced tumour growth. Both effects could be reversed by co-treatment with a potent MG-scavenger, L-Carnosine. Conclusion Our data demonstrate for the first time that cancer cells are not equal when facing MG stress. Their response to MG is mainly dependent upon energy metabolism and detoxification capacity (including GLO1 and AKRs). Reduced glutathione level is also an important feature to consider. Ongoing studies will help identify the molecular mecanisms underlying MG dual effect in cancer.

PO-219 Methylglyoxal-induced dicarbonyl stress: role in melanoma progression and response to therapy

Introduction Methylglyoxal (MG) is an endogenous dicarbonyl spontaneously produced during glycolysis able to react with proteins, lipids and DNA, inducing a carbonyl stress. Glyoxalase 1 (GLO1) detoxifies MG into D-Lactate. High MG is notably associated with diabetes and cancer. Melanoma is the most deadly form of skin cancer. Therapy is notably based on the inhibition of the MAPK pathway, often over activated. Unfortunately, BRAF and MEK inhibitors are briefly efficient as tumours rapidly develop resistance mechanisms. Melanoma tumours are generally highly glycolytic and therefore inevitably produce high amounts of MG, accumulating Advanced Glycation End products (AGEs). Phenformin, a metformin analogue with MG-scavenging properties, improves the therapeutic effect of BRAF inhibition. This observation is in good accordance with our hypothesis that MG could be involved in progression and resistance of melanoma. Material and methods This study aims to assess the metabolic profile of various human melanoma cell lines comprising BRAF and/or MEK inhibitors sensitive and resistant cells. First, we plan to explore thoroughly dicarbonyl stress status in these cell lines and in patient tissues. Next, we will subject melanoma cells to anti-carbonyl stress agents such as l-carnosine and aminoguanidine alone or in combination with MAPK pathway inhibitors and assess their effect on tumour cell survival. Results and discussions IHC staining of argpyrimidines, MG-derived AGEs, in a collection of melanoma samples showed that MG carbonyl stress is a constant feature in melanoma. MG AGEs were detectable in both BRAF inhibitors sensitive and resistant cell lines: A375 and A2058, respectively. Interestingly, the treatment of these cells with exogenous MG induced different responses: A375 cells increased their MG detoxification system and their metabolic activity as assessed by their increased GLUT1 and GLUT3 glucose transporters and PGC1alpha mitochondrial regulator. Whereas, A2058 resistant melanoma cells showed a decrease of both GLO1 activity and the metabolic markers investigated. Conclusion Ongoing experiments will help to understand these phenotypes and to further characterise a serie of WT and BRAF mutated melanoma cells. We plan to assess carbonyl stress in a larger human melanoma collection to investigate the correlation with tumour stage, metastasis, overall survival and resistance to therapy. Finally, we will test the efficacy of a combined therapy using BRAF and/or MEK inhibitors and MG scavenger molecules such as carnosine.