BCL2 and BCL(X)L selective inhibitors decrease mitochondrial ATP production in breast cancer cells and are synthetically lethal when combined with 2-deoxy-D-glucose

Abstract

Cancer cells display differences regarding their engagement of glycolytic vs. mitochondrial oxidative phosphorylation (OXPHOS) pathway. Triple negative breast cancer, an aggressive form of breast cancer, is characterized by elevated glycolysis, while estrogen receptor positive breast cancer cells rely predominantly on OXPHOS. BCL2 proteins control the process of mitochondrial outer membrane permeabilization during apoptosis, but also regulate cellular bioenergetics. Because BCL2 proteins are overexpressed in breast cancer and targetable by selective antagonists, we here analysed the effect of BCL2 and BCL(X)L selective inhibitors, Venetoclax and WEHI-539, on mitochondrial bioenergetics and cell death. Employing single cell imaging using a FRET-based mitochondrial ATP sensor, we found that MCF7 breast cancer cells supplied with mitochondrial substrates reduced their mitochondrial ATP production when treated with Venetoclax or WEHI-539 at concentrations that per se did not induce cell death. Treatments with lower concentrations of both inhibitors also reduced the length of the mitochondrial network and the dynamics, as evaluated by quantitative confocal microscopy. We next tested the hypothesis that mitochondrial ATP production inhibition with BCL2 or BCL(X)L antagonists was synthetically lethal when combined with glycolysis inhibition. Treatment with 2-deoxy-D-glucose in combination with Venetoclax or WEHI-539 synergistically reduced the cellular bioenergetics of ER+ and TNBC breast cancer cells and abolished their clonogenic potential. Synthetic lethality was also observed when cultures were grown in 3D spheres. Our findings demonstrate that BCL2 antagonists exert potent effects on cancer metabolism independent of cell death-inducing effects, and demonstrate a synthetic lethality when these are applied in combination with glycolysis inhibitors.

Metabolic Targeting of Breast Cancer Cells With the 2-Deoxy-D-Glucose and the Mitochondrial Bioenergetics Inhibitor MDIVI-1

“…However, it is now becoming increasingly evident, that BCL-2 family proteins also regulate mitochondrial fusion and fission dynamics and may regulate mitochondrial respiratory chain activity ( Chen and Pervaiz, 2007 ; Alavian et al, 2011 ; Hardwick and Soane, 2013 ; Gross, 2016 ; Williams et al, 2016 ). BCL2 and BCL(X)L selective inhibitors (Venetoclax and WEHI-539, respectively) were able to decrease mitochondrial bioenergetics and ATP production ( Lucantoni et al, 2018 ). Of note, this metabolic inhibition observed was independent of apoptosis induction.…”

Disruption of Glycogen Utilization Markedly Improves the Efficacy of Carboplatin against Preclinical Models of Clear Cell Ovarian Carcinoma

“…The glycogen depletion observed by us in OCC models potentially provides important insight into why non-clear cell types of cancer typically require several orders of magnitude higher levels of 2DG to significantly improve the efficacy of therapeutic agents. These other cancers include HGSOC [19], breast cancer [20][21][22][23], cervical cancer [24], melanoma [25], glioblastoma [26], and osteosarcoma [27], which typically require 2DG concentrations ≥ 5 mM to increase the efficacy in vitro of chemotherapies and other therapeutic agents. This contrasts with our data, which show that 0.6 mM 2DG is sufficient to significantly improve the efficacy of carboplatin against OCC cells in vitro.…”

“…Of note, these elevated 2DG concentrations employed in vitro are well above the maximum plasma levels (C max ) achieved in cancer patients in two published dose-finding clinical trials. In a study of patients with advanced solid malignancies, the maximum tolerated dose for 2DG, administered daily during the first two weeks of a three week cycle, was 45 mg/kg, resulting in a C max 0.449 mM [28], which is 10-fold lower than concentrations typically employed in in vitro studies [18][19][20][21][22][23][24][25][26][27]. In a combination trial with docetaxel for a range of advanced solid tumors, the clinically tolerable dose for 2DG, administered daily during the first and third weeks of a four week cycle during the dose-escalation phase, was 63 mg/kg/day, resulting in a C max of 0.707 mM [29].…”

“…For example, two HGSOC cell lines and malignant cells isolated from the ascites of 17 HGSOC patients, had markedly improved in vitro responses to cisplatin and carboplatin when these agents were combined with 5 or 10 mM 2DG [19]. Similar and higher concentrations of 2DG improved the responses in vitro of a range of breast cancer cell lines to mitochondria targeted drugs [20,21], a glucopyranoside [22], and inhibitors of BCL family members [23]. Analogous in vitro data have been reported for cervical cancer [24], melanoma [25], glioblastoma [26], and osteosarcoma [27].…”

Modulation of Mitochondrial Metabolic Reprogramming and Oxidative Stress to Overcome Chemoresistance in Cancer

“…Both diclofenac and lumiracoxib increase the antiglycolytic impact of vemurafenib and prevent RAF-inhibitor induced metabolic reprogramming towards OXPHOS [89]. A similar study demonstrated that the treatment of breast cancer cells with the Blc2 inhibitors Venetoclax and WEHI-539 leads to decreased OXPHOS in the absence of cell death, whereas it becomes lethal when this treatment is combined with the glycolysis inhibitor 2-Deoxy-D-glucose (2DG), even when cells are grown in three-dimensional spheroids [90]. Chaube and coworkers showed that the inhibition of complex I by metformin in melanoma cells leads to growth arrest because of enhanced glycolysis and consequent extracellular acidification in vitro, but promotes melanoma growth in mice by increasing lactate and VEGF levels.…”