Oxygenated cancer cells have a high metabolic plasticity as they can use glucose, glutamine and lactate as main substrates to support their bioenergetic and biosynthetic activities. Metabolic optimization requires integration. While glycolysis and glutaminolysis can cooperate to support cellular proliferation, oxidative lactate metabolism opposes glycolysis in oxidative cancer cells engaged in a symbiotic relation with their hypoxic/glycolytic neighbors. However, little is known concerning the relationship between oxidative lactate metabolism and glutamine metabolism. Using SiHa and HeLa human cancer cells, this study reports that intracellular lactate signaling promotes glutamine uptake and metabolism in oxidative cancer cells. It depends on the uptake of extracellular lactate by monocarboxylate transporter 1 (MCT1). Lactate first stabilizes hypoxia-inducible factor-2α (HIF-2α), and HIF-2α then transactivates c-Myc in a pathway that mimics a response to hypoxia. Consequently, lactate-induced c-Myc activation triggers the expression of glutamine transporter ASCT2 and of glutaminase 1 (GLS1), resulting in improved glutamine uptake and catabolism. Elucidation of this metabolic dependence could be of therapeutic interest. First, inhibitors of lactate uptake targeting MCT1 are currently entering clinical trials. They have the potential to indirectly repress glutaminolysis. Second, in oxidative cancer cells, resistance to glutaminolysis inhibition could arise from compensation by oxidative lactate metabolism and increased lactate signaling.

The degradation of the extracellular matrix by cancer cells represents an essential step in metastatic progression and this is performed by cancer cell structures called invadopodia. NaV1.5 sodium channels are overexpressed in breast tumours and associated with metastatic occurrence. NaV1.5 activity was shown to enhance breast cancer cell invasiveness through perimembrane acidification and subsequent degradation of the extracellular matrix by cysteine cathepsins. Here, we showed that NaV1.5 was co-localised with NHE-1, and caveolin-1 in MDA-MB-231 breast cancer cells invadopodia, at sites of matrix remodelling. NHE-1, NaV1.5 and caveolin-1 co-immunoprecipitated, which indicated a close association between these proteins. The expression of NaV1.5 was responsible for the allosteric modulation of NHE-1 rendering it more active at intracellular pH range 6.4 to 7, thus potentially extruding more protons in the extracellular space. Furthermore, NaV1.5 increased Src kinase activity and the phosphorylation (Y421) of the actin-nucleation-promoting factor cortactin, controlled F-actin polymerization and the acquisition of an invasive morphology. Taken together, our study suggests that NaV1.5 is a central regulator of invadopodia formation and activity in breast cancer cells.

Cardiolipins (CLs) are specific phospholipids of the mitochondria composing about 20% of the inner mitochondria membrane (IMM) phospholipid mass. Dysregulation of CL metabolism has been observed in several types of cancer. In most cases, the evidence for a role for CL in cancer is merely correlative, suggestive, ambiguous, and cancer-type dependent. In addition, CLs could play a pivotal role in several mitochondrial functions/parameters such as bioenergetics, dynamics, mitophagy, and apoptosis, which are involved in key steps of cancer aggressiveness (i.e., migration/invasion and resistance to treatment). Therefore, this review focuses on studies suggesting that changes in CL content and/or composition, as well as CL metabolism enzyme levels, may be linked with the progression and the aggressiveness of some types of cancer. Finally, we also introduce the main mitochondrial function in which CL could play a pivotal role with a special focus on its implication in cancer development and therapy.