Advancing Cancer Treatment by Targeting Glutamine Metabolism-A Roadmap

The Juggernaut of Adaptive Metabolism in Cancers: Implications and Therapeutic Targets

The disease of cancer instills a sense of fear and dread among patients and the next of kin who are indirectly affected by the deteriorating quality of life of their loved ones [...]

mTORC1-Inhibition Potentiating Metabolic Block by Tyrosine Kinase Inhibitor Ponatinib in Multiple Myeloma

Simple Summary

From a screen for metabolic inhibition by a panel of approved anticancer drugs and combining the lead compound with a mammalian target of rapamycin complex 1 (mTORC1) inhibitor, we demonstrated that the combination of ponatinib and sirolimus leads to synergistic tumor growth inhibition in a mouse xenograft tumor model of multiple myeloma. The rationale of combining the two drugs was to prevent metabolic escape due to glycolysis reprogramming and residual oxidative phosphorylation (OXPHOS). The robust increases in reactive oxygen species (ROS) due to a block in glycolysis were shown to be the lead contributor of cell viability loss. The drug combination in the doses used displayed no overt toxicity in the treated animals.

Abstract

Studies in targeting metabolism in cancer cells have shown the flexibility of cells in reprogramming their pathways away from a given metabolic block. Such behavior prompts a combination drug approach in targeting cancer metabolism, as a single compound may not address the tumor intractability. Overall, mammalian target of rapamycin complex 1 (mTORC1) signaling has been implicated as enabling metabolic escape in the case of a glycolysis block. From a library of compounds, the tyrosine kinase inhibitor ponatinib was screened to provide optimal reduction in metabolic activity in the production of adenosine triphosphate (ATP), pyruvate, and lactate for multiple myeloma cells; however, these cells displayed increasing levels of oxidative phosphorylation (OXPHOS), enabling them to continue generating ATP, although at a slower pace. The combination of ponatinib with the mTORC1 inhibitor, sirolimus, blocked OXPHOS; an effect also manifested in activity reductions for hexokinase 2 (HK2) and glucose-6-phosphate isomerase (GPI) glycolysis enzymes. There were also remarkably higher levels of reactive oxygen species (ROS) produced in mouse xenografts, on par with increased glycolytic block. The combination of ponatinib and sirolimus resulted in synergistic inhibition of tumor xenografts with no overt toxicity in treated mice for kidney and liver function or maintaining weight.

Regulation of growth, invasion and metabolism of breast ductal carcinoma through CCL2/CCR2 signaling interactions with MET receptor tyrosine kinases

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CCR2 correlates with MET receptor expression in breast ductal carcinomas.

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CCL2/CCR2 signaling in breast cancer cells depend on interactions with MET.

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CCR2 and MET signals alter metabolism of ductal carcinoma in situ in animal models.

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CCR2 mediates metabolism and progression of MIND lesions through MET.

With over 60,000 cases diagnosed annually in the US, ductal carcinoma in situ (DCIS) is the most prevalent form of early-stage breast cancer. Because many DCIS cases never progress to invasive ductal carcinomas (IDC), overtreatment remains a significant problem. Up to 20% patients experience disease recurrence, indicating that standard treatments do not effectively treat DCIS for a subset of patients. By understanding the mechanisms of DCIS progression, we can develop new treatment strategies better tailored to patients. The chemokine CCL2 and its receptor CCR2 are known to regulate macrophage recruitment during inflammation and cancer progression. Recent studies indicate that increased CCL2/CCR2 signaling in breast epithelial cells enhance formation of IDC. Here, we characterized the molecular mechanisms important for CCL2/CCR2-mediated DCIS progression. Phospho-protein array profiling revealed that CCL2 stimulated phosphorylation of MET receptor tyrosine kinases in breast cancer cells. Co-immunoprecipitation and proximity ligation assays demonstrated that CCL2-induced MET activity depended on interactions with CCR2 and SRC. Extracellular flux analysis and biochemical assays revealed that CCL2/CCR2 signaling in breast cancer cells enhanced glycolytic enzyme expression and activity. CRISPR knockout and pharmacologic inhibition of MET revealed that CCL2/CCR2-induced breast cancer cell proliferation, survival, migration and glycolysis through MET-dependent mechanisms. In animals, MET inhibitors blocked CCR2-mediated DCIS progression and metabolism. CCR2 and MET were significantly co-expressed in patient DCIS and IDC tissues. In summary, MET receptor activity is an important mechanism for CCL2/CCR2-mediated progression and metabolism of early-stage breast cancer, with important clinical implications.