Attenuation of Adverse Postinfarction Left Ventricular Remodeling with Empagliflozin Enhances Mitochondria-Linked Cellular Energetics and Mitochondrial Biogenesis

Sodium–glucose cotransporter 2 (SGLT2) inhibitors such as empagliflozin are known to reduce the risk of hospitalizations related to heart failure irrespective of diabetic state. Meanwhile, adverse cardiac remodeling remains the leading cause of heart failure and death in the USA. Thus, understanding the mechanisms that are responsible for the beneficial effects of SGLT2 inhibitors is of the utmost relevance and importance. Our previous work illustrated a connection between adverse cardiac remodeling and the regulation of mitochondrial turnover and cellular energetics using a short-acting glucagon-like peptide-1 receptor agonist (GLP1Ra). Here, we sought to determine if the mechanism of the SGLT2 inhibitor empagliflozin (EMPA) in ameliorating adverse remodeling was similar and/or to identify what differences exist, if any. To this end, we administered permanent coronary artery ligation to induce adverse remodeling in wild-type and Parkin knockout mice and examined the progression of adverse cardiac remodeling with or without EMPA treatment over time. Like GLP1Ra, we found that EMPA affords a robust attenuation of PCAL-induced adverse remodeling. Interestingly, unlike the GLP1Ra, EMPA does not require Parkin to improve/maintain mitochondria-related cellular energetics and afford its benefits against developing adverse remodeling. These findings suggests that further investigation of EMPA is warranted as a potential path for developing therapy against adverse cardiac remodeling for patients that may have Parkin and/or mitophagy-related deficiencies.

Ibogaine Has Sex-Specific Plasma Bioavailability, Histopathological and Redox/Antioxidant Effects in Rat Liver and Kidneys: A Study on Females

Ibogaine induces rapid changes in cellular energetics followed by the elevation of antioxidant activities. As shown earlier in male rats, ibogaine treatment with both 1 and 20 mg/kg b.w. per os led to significant glycogenolytic activity in the liver. In this work, female rats treated with the same doses of ibogaine per os displayed lower liver glycogenolytic activity relative to males, dilatation of the central vein and branches of the portal vein, and increased concentration of thiols 6 h after treatment. These changes were followed by increased catalase activity and lipid peroxidation, and decreased xanthine oxidase activity after 24 h. In kidneys, mild histopathological changes were found in all treated animals, accompanied by a decrease of glutathione reductase (after 6 and 24 h at both doses) and an increase of catalase (6 h) and xanthine oxidase activity (6 and 24 h). Ibogaine did not affect antioxidant enzymes activity in erythrocytes. Bioavailability of ibogaine was two to three times higher in females than males, with similar kinetic profiles. Compared to previous results in males, ibogaine showed sex specific effect at the level of antioxidant cellular system. Effects of ibogaine in rats are sex- and tissue-specific, and also dose- and time-dependent.

Mitochondrial Mechanisms of Apoptosis and Necroptosis in Liver Diseases

In addition to playing a pivotal role in cellular energetics and biosynthesis, mitochondrial components are key operators in the regulation of cell death. In addition to apoptosis, necrosis is a highly relevant form of programmed liver cell death. Differential activation of specific forms of programmed cell death may not only affect the outcome of liver disease but may also provide new opportunities for therapeutic intervention. This review describes the role of mitochondria in cell death and the mechanism that leads to chronic liver hepatitis and liver cirrhosis. We focus on mitochondrial-driven apoptosis and current knowledge of necroptosis and discuss therapeutic strategies for targeting mitochondrial-mediated cell death in liver diseases.

IGF1R-IRS1/2 Pharmacological Inhibitors Act By Distinct Cellular and Molecular Mechanisms and Reveals Vulnerabilities for Treatment of Acute Myeloid Leukemia

Background: Preclinical rationale for targeting the insulin-like growth factor 1 (IGF1R)-Insulin Receptor Substrates 1 and 2 (IRS1/2) signaling in acute myeloid leukemia (AML), particularly in cells harboring the FLT3-ITD mutation, has been recently provided [Blood (2018) 132 Supp: 1512 and [Blood (2019) 134 Supp: 2689]. However, little is known about the non-canonical molecular mechanisms regulated by IGF1R-IRS1/2 signaling and pharmacological inhibition of this pathway in AML. Aims: To depict distinctive non-explicit molecular effects of linsitinib (IGF1R tyrosine kinase inhibitor) and NT157 (IGF1R-IRS1/2 allosteric inhibitor) treatment in FLT3-ITD-mutated AML cells. Material and methods: The MOLM-13 (homozygous) and MV4-11 (heterozygous) FLT3-ITD-mutated AML cell lines were treated with linsitinib (10 µM) or NT157 (1 µM) for 24 hours and used for label-free proteomic quantification analysis (n=3). Raw MS/MS data were processed using the SORCERER system and proteins were identified with built-in Andromeda search engine based on the human Uniprot proteome database. False discovery rate cutoffs were set to 1% on peptide, protein, and site decoy level, only allowing high quality identification to pass. Expression values were normalized across experimental conditions by quantile normalization based on the Limma-Voom pipeline, and then systematically compared similarities and differences in protein expression across experimental conditions by applying the Benjamin-Hochberg correction for multiple comparisons. To depict pathways associated to IGF1R, IRS1 and IRS2 gene expression related to processes identified by the proteomic data, we performed a gene-set enrichment analysis (GSEA) using the curated genesets for oncogenic events and molecular functions (MSigDB, Broad Institute) from RNA-seq data of the Cancer Genome Atlas AML cohort (n=173). Results: Considering a ≥ 2-fold change difference in both directions, linsitinib treatment downregulated 6 and 18 and upregulated 13 and 116 proteins in MOLM-13 and MV4-11 cells, respectively. Likewise, NT157 downregulated 12 and 126 and upregulated 204 and 297 proteins. When compared directly, linsitinib reduced expression of 11 and 35 and increased expression of 110 and 70 proteins in MOLM-13 and MV4-11 cells, respectively. Gene ontology identified that linsitinib resulted in upregulation of 7 molecular functions, while the NT157 ensued the upregulation of 18 and downregulation of 17 molecular functions pathways in a consistently manner between all comparisons. Of note, linsitinib activates post-transcriptional regulatory mechanisms, RNA metabolism (RNA binding P=1.15E-12; RNA processing P=8.64E-7) and reduced the protein and macromolecule metabolism (cellular protein metabolism P=3.86E-6). NT157 affected several of mitochondrial functions (increasing proton transmembrane transport activity P=1.55E-12, reducing oxidoreductase activity P=9.11E-10, and oxidative phosphorylation P=5.19E-8). Altogether, these data highlighted that NT157 profounder cytotoxic effect is a result of reprogramming of cellular energetics metabolism, and that linsitinib altered transcription and translation processes, probably as a result of autophagy, a mechanism originally described by our group [Blood (2017) 130 Supp: 3966]. GSEA analysis revealed that high IGF1R expression is positively enriched with RPS14 signature (Normalized Enriched Score [NES]=2.23; FDR-q<0.001), a ribosomal protein related to pathophysiology of myeloid neoplasms related to chromosome 5q deletion. Both IRS1 and IRS2 transcriptional signatures were associated with cellular growth signaling, such as AKT (NES=1.86; FDR-q= 0.006) and MYC (NES=1.67; FDR-q= 0.005), mitochondrial function [mitochondrial gene expression (NES=1.71; FDR-q= 0.001)]. Conclusion: Our proteomic data shed light on new and non-explicit mechanisms related to IGF1R-IRS1/2 inhibitors. Linsitinib modulates molecular processes related to RNA transcription and translation, while NT157 profoundly affect the cellular energetics, and, at least in part, explain the differential pre-clinical efficiency. Moreover, allosteric pharmacological inhibition of IGF1R-IRS1/2 pathway seems a more promising strategy than the tyrosine kinase inhibition, especially for AML subgroup more dependent of mitochondrial metabolism, such as AML with FLT3 mutation. Disclosures No relevant conflicts of interest to declare.

Returning to the Hallmarks of Cancer: A Brief Review and Revision

The hallmarks of cancer represent principals and mechanisms on which, different types of cancers function and proliferate, These principals which also include the revised edition include sustained proliferative signaling, Evading growth suppressors , avoiding immune destruction, enabling replicative immortality, tumor promoting inflammation, activating invasion and metastasis, Inducing angiogenesis, genome instability and mutation, resisting cell death, deregulating cellular energetics. This article reviews these hallmarks and suggests any additional hallmark that can be further investigated and integrated into the revised edition , Hanahan and Weinberg’s hallmark of cancer are great pillars of understanding for modern cancer study and are open to modification , making it easily approachable ,critiqued and adds the possibility of additions in the near future. The role of exosomes are discussed with the potential to categorize drug resistance as a separate hallmark to assist us in developing therapeutics that can counter or bypass these mechanisms that assist cancer cells to proliferate even further.

Bacteria–Cancer Interface: Awaiting the Perfect Storm

Epidemiological evidence reveal a very close association of malignancies with chronic inflammation as a result of persistent bacterial infection. Recently, more studies have provided experimental evidence for an etiological role of bacterial factors disposing infected tissue towards carcinoma. When healthy cells accumulate genomic insults resulting in DNA damage, they may sustain proliferative signalling, resist apoptotic signals, evade growth suppressors, enable replicative immortality, and induce angiogenesis, thus boosting active invasion and metastasis. Moreover, these cells must be able to deregulate cellular energetics and have the ability to evade immune destruction. How bacterial infection leads to mutations and enriches a tumour-promoting inflammatory response or micro-environment is still not clear. In this review we showcase well-studied bacteria and their virulence factors that are tightly associated with carcinoma and the various mechanisms and pathways that could have carcinogenic properties.

Spatial regulation of AMPK signaling revealed by a sensitive kinase activity reporter

AMP-activated protein kinase (AMPK) is a master regulator of cellular energetics which coordinates metabolism by phosphorylating a plethora of substrates throughout the cell. But whether AMPK activity is regulated at different subcellular locations to provide precise spatial and temporal control over metabolism is unclear. Genetically encoded AMPK activity reporters (AMPKAR) have provided a window into spatial AMPK activity, but the limited dynamic range of current AMPKARs hinders detailed study. To monitor the dynamic activity of AMPK with high sensitivity, we developed a single-fluorophore AMPK activity reporter (ExRai AMPKAR) that exhibits an excitation ratiometric fluorescence change upon phosphorylation by AMPK, with over 3-fold greater response compared to previous AMPKARs. Using subcellularly localized ExRai AMPKAR, we found that the activity of AMPK at the lysosome and mitochondria are differentially regulated. While different activating conditions, irrespective of their effects on ATP, robustly yet gradually increase mitochondrial AMPK activity, lysosomal AMPK activity accumulates with much faster kinetics. Genetic deletion of the canonical upstream kinase liver kinase B1 (LKB1) resulted in slower AMPK activity at lysosomes but did not affect the response amplitude at either location, in sharp contrast to the necessity of LKB1 for maximal cytoplasmic AMPK activity. We further discovered AMPK activity in the nucleus, which resulted from LKB1-mediated cytoplasmic activation of AMPK followed by nuclear shuttling. Thus, a new, sensitive reporter for AMPK activity, ExRai AMPKAR, in complement with mathematical and biophysical methods, captured subcellular AMPK activity dynamics in living cells and unveiled complex regulation of AMPK signaling within subcellular compartments.

Mitochondria-localized AMPK responds to local energetics and contributes to exercise and energetic stress-induced mitophagy

Mitochondria form a complex, interconnected reticulum that is maintained through coordination among biogenesis, dynamic fission, and fusion and mitophagy, which are initiated in response to various cues to maintain energetic homeostasis. These cellular events, which make up mitochondrial quality control, act with remarkable spatial precision, but what governs such spatial specificity is poorly understood. Herein, we demonstrate that specific isoforms of the cellular bioenergetic sensor, 5′ AMP-activated protein kinase (AMPKα1/α2/β2/γ1), are localized on the outer mitochondrial membrane, referred to as mitoAMPK, in various tissues in mice and humans. Activation of mitoAMPK varies across the reticulum in response to energetic stress, and inhibition of mitoAMPK activity attenuates exercise-induced mitophagy in skeletal muscle in vivo. Discovery of a mitochondrial pool of AMPK and its local importance for mitochondrial quality control underscores the complexity of sensing cellular energetics in vivo that has implications for targeting mitochondrial energetics for disease treatment.

MYC Rules: Leading Glutamine Metabolism toward a Distinct Cancer Cell Phenotype

Metabolic reprogramming and deregulated cellular energetics are hallmarks of cancer. The aberrant metabolism of cancer cells is thought to be the product of differential oncogene activation and tumor suppressor gene inactivation. MYC is one of the most important oncogenic drivers, its activation being reported in a variety of cancer types and sub-types, among which are the most prevalent and aggressive of all malignancies. This review aims to offer a comprehensive overview and highlight the importance of the c-Myc transcription factor on the regulation of metabolic pathways, in particular that of glutamine and glutaminolysis. Glutamine can be extensively metabolized into a variety of substrates and be integrated in a complex metabolic network inside the cell, from energy metabolism to nucleotide and non-essential amino acid synthesis. Together, understanding metabolic reprogramming and its underlying genetic makeup, such as MYC activation, allows for a better understanding of the cancer cell phenotype and thus of the potential vulnerabilities of cancers from a metabolic standpoint.

Hallmarks of Cancers: Primary Antibody Deficiency Versus Other Inborn Errors of Immunity

Inborn Errors of Immunity (IEI) comprise more than 450 inherited diseases, from which selected patients manifest a frequent and early incidence of malignancies, mainly lymphoma and leukemia. Primary antibody deficiency (PAD) is the most common form of IEI with the highest proportion of malignant cases. In this review, we aimed to compare the oncologic hallmarks and the molecular defects underlying PAD with other IEI entities to dissect the impact of avoiding immune destruction, genome instability, and mutation, enabling replicative immortality, tumor-promoting inflammation, resisting cell death, sustaining proliferative signaling, evading growth suppressors, deregulating cellular energetics, inducing angiogenesis, and activating invasion and metastasis in these groups of patients. Moreover, some of the most promising approaches that could be clinically tested in both PAD and IEI patients were discussed.