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There is currently no consensus to determine which advanced melanoma patients will benefit from immunotherapy, highlighting the critical need to identify early-response biomarkers to immune checkpoint inhibitors. The aim of this work was to evaluate in vivo metabolic spectroscopy using hyperpolarized (HP) 13C-pyruvate and 13C-glucose to assess early response to anti-PD1 therapy in the YUMMER1.7 syngeneic melanoma model. The xenografts showed a significant tumor growth delay when treated with two cycles of an anti-PD1 antibody compared to an isotype control antibody. 13C-MRS was performed in vivo after the injection of hyperpolarized 13C-pyruvate, at baseline and after one cycle of immunotherapy, to evaluate early dynamic changes in 13C-pyruvate–13C-lactate exchange. Furthermore, ex vivo 13C-MRS metabolic tracing experiments were performed after U-13C-glucose injection following one cycle of immunotherapy. A significant decrease in the ratio of HP 13C-lactate to 13C-pyruvate was observed in vivo in comparison with the isotype control group, while there was a lack of change in the levels of 13C lactate and 13C alanine issued from 13C glucose infusion, following ex vivo assessment on resected tumors. Thus, these results suggest that hyperpolarized 13C-pyruvate could be used to assess early response to immune checkpoint inhibitors in melanoma patients.

Obesity is characterized by an excessive fat mass accumulation associated with multiple disorders, including impaired glucose homeostasis, altered adipokine levels, and hyperlipidemia. Despite clear associations between tumor progression and obesity, the effects of these disorders on tumor metabolism remain largely unknown. Thus, we studied the metabolic differences between tumors of obese and lean mice in murine models of triple-negative breast cancer (E0771 and PY8819). For this purpose, a real-time hyperpolarized 1-13C-pyruvate-to-lactate conversion was studied before and after glucose administration in fasting mice. This work was completed by U-13C glucose tracing experiments using nuclear magnetic resonance (NMR) spectroscopy, as well as mass spectrometry (MS). Ex vivo analyses included immunostainings of major lipid, glucose, and monocarboxylic acids transporters. On the one hand, we discovered that tumors of obese mice yield higher lactate/pyruvate ratios after glucose administration. On the other hand, we found that the same tumors produce higher levels of lactate and alanine from glucose than tumors from lean mice, while no differences on the expression of key transporters associated with glycolysis (i.e., GLUT1, MCT1, MCT4) have been observed. In conclusion, our data suggests that breast tumor metabolism is regulated by the host’s physiological status, such as obesity and diabetes.

In Oncology, chemoresistance is often responsible for therapeutic failure. In this work where we used human cancer models, we investigated whether precise metabolic changes could account for chemoresistance. Not only in cisplatin-resistant ovarian cancer but also in temozolomide-resistant glioblastoma, we evidenced highly oxidative chemoresistant phenotypes depending on mitophagy. Consequently, inhibiting either mitophagy by more largely blocking autophagy or cell respiration by targeting Complex I in the electron transport chain with olaparib allowed to resensitize cancer cells to cisplatin and/or to temozolomide. We propose that these two approaches used in combination therapies with selected forms of chemotherapy would be attractive for countering cancer chemoresistance., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Metabolic plasticity in cancer cells makes very challenging the use of metabolism-targeting agents as monotherapy due to resistance establishment. Moreover, the use of these drugs as anticancer treatments will not only affect cancer cells, but also immune cells in the tumor microenvironment and thereby might abrogate the beneficial effects of immunotherapy. In the first part of our work, we report that exposure to 3-bromopyruvate, a glycolysis inhibitor, renders cancer cells vulnerable to the blockade of monocarboxylate transporter 4 activity, which prevents resistant cells to growth. In the second part of this thesis, we show that acute treatment of activated T cells with fatty acid oxidation inhibitor leads to an increase of their proliferation in vitro, and to higher cytotoxic capacities towards melanoma cancer cells. Altogether our data offer metabolism-targeting therapeutic strategies to overcome resistance from plastic cancer cells and to potentiate benefits of immunotherapies., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Ovarian tissue cryopreservation and further transplantation has proved its effectiveness in restoring fertility after cancer, with over 200 live births worldwide to date. However, it is limited by massive ischemic damage that occurs shortly after transplantation, causing a significant decline in the ovarian reserve. This project aimed to develop a novel strategy using adipose tissue-derived stem cells (ASCs) for ovarian tissue transplantation, after our preliminary results revealed their impact on hypoxia and revascularization. ASCs are able to protect the ovarian reserve from hypoxic damage, thereby reducing follicle loss. Moreover, their secretome, rich in growth factors, is able to both enhance graft revascularization and reperfusion, and mitigate the primordial follicle burn-out due to abnormal activation soon after transplantation. The present work proved the effecicacy of ASC use in ovarian tissue transplantation, which is now one step closer to clinical application., (MED - Sciences médicales) -- UCL, 2022

A vast majority of BRAF V600E mutated melanoma patients will develop resistance to combined BRAF/MEK inhibition after initial clinical response. Resistance to targeted therapy is described to be accompanied by specific metabolic changes in melanoma. The aim of this work was to evaluate metabolic imaging using 13C-MRS (Magnetic Resonance Spectroscopy) as a marker of response to BRAF/MEK inhibition in a syngeneic melanoma model. Tumor growth was significantly delayed in mice bearing YUMM1.7 melanoma xenografts treated with the BRAF inhibitor vemurafenib, and/or with the MEK inhibitor trametinib, in comparison with the control group. 13C-MRS was performed in vivo after injection of hyperpolarized (HP) 13C-pyruvate, at baseline and 24 h after treatment, to evaluate dynamic changes in pyruvate-lactate exchange. Furthermore, ex vivo 13C-MRS steady state metabolic tracing experiments were performed after U-13C-glucose or 5-13C-glutamine injection, 24 h after treatment. The HP 13C-lactate-to-pyruvate ratio was not modified in response to BRAF/MEK inhibition, whereas the production of 13C-lactate from 13C-glucose was significantly reduced 24 h after treatment with vemurafenib, trametinib, or with the combined inhibitors. Conversely, 13C-glutamine metabolism was not modified in response to BRAF/MEK inhibition. In conclusion, we identified 13C-glucose fluxomic as a potential marker of response to BRAF/MEK inhibition in YUMM1.7 melanoma xenografts.

Cancer cachexia is a complex multi-organ syndrome characterised by body weight loss, weakness, muscle atrophy and fat depletion. The modulation of the gut microbiota, an important regulator of the host metabolism, has shown therapeutic potential. To evaluate the contribution of gut microbiota alterations to the metabolic dysfunctions observed in cancer cachexia, we first investigated the role of Klebsiella oxytoca. We found that this Enterobacteriaceae species acts as a gut pathobiont by altering the gut barrier function in cachectic mice. Then, a multi –omics strategy revealed multiple host metabolic alterations and a reduction of different beneficial intestinal bacterial activities in cachectic mice. Finally, we used a multi –omics approach to show that acute myeloid leukemic patients display gut microbiome alterations at diagnosis. Such alterations may contribute to metabolic and inflammatory dysregulations in those patients. By combining preclinical and clinical data, this thesis work pinpoints important metabolic and microbial alterations in cancer cachexia and shows the interest of this research field for future therapeutic applications., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Solid tumors are generally characterized by an acidic tumor microenvironment (TME) that favors cancer progression, therapy resistance, and immune evasion. By single-cell RNA-sequencing analysis in PDAC patients, we reveal hereby Solute Carrier Family 4 Member 4 (SLC4A4) as the most abundant bicarbonate transporter, predominantly expressed by epithelial ductal cells. Functionally, SLC4A4 inhibition in PDAC cancer cells mitigates the acidosis of the TME due to bicarbonate accumulation in the extracellular space and decrease in lactate production by cancer cells as the result of reduced glycolysis. In PDAC-bearing mice, genetic or pharmacological SLC4A4 targeting improves T cell-mediated immune response and breaches macrophage-mediated immunosuppression, thus inhibiting tumor growth and metastases. In addition, Slc4a4 targeting in combination with immune-checkpoint blockade is able to overcome immunotherapy resistance and prolong survival. Overall, our data propose SLC4A4 as a therapeutic target to unleash an anti-tumor immune response in PDAC.

Mito-metformin10 (MM10), synthesized by attaching a triphenylphosphonium cationic moiety via a 10-carbon aliphatic side chain to metformin, is a mitochondria-targeted analog of metformin that was recently demonstrated to alter mitochondrial function and proliferation in pancreatic ductal adenocarcinoma. Here, we hypothesized that this compound may decrease the oxygen consumption rate (OCR) in prostate cancer cells, increase the level of mitochondrial ROS, alleviate tumor hypoxia, and radiosensitize tumors. OCR and mitochondrial superoxide production were assessed by EPR (9 GHz) in vitro in PC-3 and DU-145 prostate cancer cells. Reduced and oxidized glutathione were assessed before and after MM10 exposure. Tumor oxygenation was measured in vivo using 1 GHz EPR oximetry in PC-3 tumor model. Tumors were irradiated at the time of maximal reoxygenation. 24-hours exposure to MM10 significantly decreased the OCR of PC-3 and DU-145 cancer cells. An increase in mitochondrial superoxide levels was observed in PC-3 but not in DU-145 cancer cells, an observation consistent with the differences observed in glutathione levels in both cancer cell lines. In vivo, the tumor oxygenation significantly increased in the PC-3 model (daily injection of 2 mg/kg MM10) 48 and 72 h after initiation of the treatment. Despite the significant effect on tumor hypoxia, MM10 combined to irradiation did not increase the tumor growth delay compared to the irradiation alone. MM10 altered the OCR in prostate cancer cells. The effect of MM10 on the superoxide level was dependent on the antioxidant capacity of cell line. In vivo, MM10 alleviated tumor hypoxia, yet without consequence in terms of response to irradiation.

(1) Background: Because statins were found to decrease the oxygen consumption rate (OCR) of a variety of normal cells, our hypothesis was that statins may also decrease the OCR of cancer cells, alleviate tumor hypoxia and radiosensitize tumors. (2) Methods: OCR was assessed using the Seahorse XF96 technology and EPR respirometry in PC-3 prostate cancer cells. Mitochondrial superoxide production was measured by EPR with mitoTEMPO-H as a sensing probe. Tumor pO2 was measured in vivo using low-frequency EPR oximetry to define the optimal window of reoxygenation, the time at which tumors were irradiated with a single 6 Gy dose with a Cesium-137 irradiator. (3) Results: 24-h exposure to simvastatin and fluvastatin significantly decreased the OCR of PC-3 cancer cells. An increase in mitochondrial superoxide levels was also observed after fluvastatin exposure. The PC-3 prostate cancer model was found highly hypoxic at the basal level. When mice were treated with simvastatin or fluvastatin (daily injection of 20 mg/kg), tumor oxygenation increased 48 and 72 h after initiation of the treatment. However, despite reoxygenation, simvastatin did not sensitize the PC-3 tumor model to RT. (4) Conclusions: exposure to statins affect tumor metabolism and tumor oxygenation, however, with limited impact on tumor growth with or without irradiation.