Z. are inventors of two pending patent applications for use of BCL-X L PROTACs as senolytic and antitumor agents. R.H., G.Z., and D.Z. are co-founders of and have equity in Dialectic Therapeutics, which develops BCL-X L PROTACs to treat cancer.
Metformin, a well-known anti-diabetic agent, is very effective in lowering blood glucose in patients with type 2 diabetes with minimal side-effects. Metformin is also being recommended in the treatment of obesity and polycystic ovary syndrome. Metformin elicits its therapeutic effects mainly via activation of AMP-activated kinase (AMPK) pathway. Renal cells under hyperglycemic or proteinuric conditions exhibit inactivation of cell defense mechanisms such as AMPK and autophagy, and activation of pathologic pathways such as mammalian target of rapamycin (mTOR), endoplasmic reticulum (ER) stress, epithelial-to-mesenchymal transition (EMT), oxidative stress, and hypoxia. As these pathologic pathways are intertwined with AMPK signaling, the potential benefits of metformin therapy in patients with type 2 diabetes would extend beyond its anti-hyperglycemic effects. However, since metformin is eliminated unchanged through the kidneys and some studies have shown the incidence of lactic acidosis with its use during severe renal dysfunction, the use of metformin was contraindicated in patients with renal disease until recently. With more studies indicating the relatively low incidence of lactic acidosis and revealing the additional benefits with metformin therapy, the US FDA has now approved metformin to be administered in patients with established renal disease based on their renal function. The purpose of this review is to highlight the various mechanisms by which metformin protects renal cells that have lost its functionality in a diabetic or non-diabetic setting and to enlighten the advantages and therapeutic potential of metformin as a nephroprotectant for patients with diabetic nephropathy and other non-diabetic forms of chronic kidney disease. J. Cell. Physiol. 232: 731-742, 2017. © 2016 Wiley Periodicals, Inc.
Venetoclax combines synergistically with FLT3 inhibition to effectively target leukemic cells in FLT3-ITD+ acute myeloid leukemia models
Acute myeloid leukemia (AML) cells are highly dependent on oxidative phosphorylation (OxPhos) for survival and continually adapt to fluctuations in nutrient and oxygen availability in the bone marrow (BM) microenvironment. We investigated how the BM microenvironment affects the response to OxPhos inhibition in AML by using a novel complex I OxPhos inhibitor, IACS-010759. Cellular adhesion, growth, and apoptosis assays, along with measurements of mtDNA expression and mitochondrial reactive oxygen species generation, indicated that direct interactions with BM stromal cells triggered compensatory activation of mitochondrial respiration and resistance to OxPhos inhibition in AML cells. Mechanistically, OxPhos inhibition induced (1) transfer of mesenchymal stem cell (MSC)-derived mitochondria to AML cells via tunneling nanotubes under direct-contact coculture conditions, and (2) mitochondrial fission with an increase in functional mitochondria and mitophagy in AML cells. Mitochondrial fission is known to enhance cell migration, and we observed mitochondrial transport to the leading edge of protrusions of migrating AML cells toward MSCs by electron microscopy analysis. We further demonstrated that cytarabine, a commonly used antileukemia agent, increased OxPhos inhibition-triggered mitochondrial transfer from MSCs to AML cells. Our findings indicate an important role of exogenous mitochondrial trafficking from BM stromal cells to AML cells as well as endogenous mitochondrial fission and mitophagy in the compensatory adaptation of leukemia cells to energetic stress in the BM microenvironment.
T-cell acute lymphoblastic leukemia (T-ALL) is commonly driven by activating mutations in NOTCH1 that facilitate glutamine oxidation. Here we identify oxidative phosphorylation (OxPhos) as a critical pathway for leukemia cell survival and demonstrate a direct relationship between NOTCH1, elevated OxPhos gene expression, and acquired chemoresistance in pre-leukemic and leukemic models. Disrupting OxPhos with IACS-010759, an inhibitor of mitochondrial complex I, causes potent growth inhibition through induction of metabolic shut-down and redox imbalance in NOTCH1-mutated and less so in NOTCH1-wt T-ALL cells. Mechanistically, inhibition of OxPhos induces a metabolic reprogramming into glutaminolysis. We show that pharmacological blockade of OxPhos combined with inducible knock-down of glutaminase, the key glutamine enzyme, confers synthetic lethality in mice harboring NOTCH1-mutated T-ALL. We leverage on this synthetic lethal interaction to demonstrate that IACS-010759 in combination with chemotherapy containing L-asparaginase, an enzyme that uncovers the glutamine dependency of leukemic cells, causes reduced glutaminolysis and profound tumor reduction in pre-clinical models of human T-ALL. In summary, this metabolic dependency of T-ALL on OxPhos provides a rational therapeutic target.
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