Is oxidative stress MYC’s Achilles heel?

No abstract available

Limited mitochondrial permeabilisation causes DNA-damage and genomic instability in the absence of cell death

During apoptosis, the mitochondrial outer membrane is permeabilized, leading to the release of cytochrome c that activates downstream caspases. Mitochondrial outer membrane permeabilization (MOMP) has historically been thought to occur synchronously and completely throughout a cell, leading to rapid caspase activation and apoptosis. Using a new imaging approach, we demonstrate that MOMP is not an all-or-nothing event. Rather, we find that a minority of mitochondria can undergo MOMP in a stress-regulated manner, a phenomenon we term "minority MOMP." Crucially, minority MOMP leads to limited caspase activation, which is insufficient to trigger cell death. Instead, this caspase activity leads to DNA damage that, in turn, promotes genomic instability, cellular transformation, and tumorigenesis. Our data demonstrate that, in contrast to its well-established tumor suppressor function, apoptosis also has oncogenic potential that is regulated by the extent of MOMP. These findings have important implications for oncogenesis following either physiological or therapeutic engagement of apoptosis

Developmental regulation of mitochondrial apoptosis by c-Myc governs age- and tissue-specific sensitivity to cancer therapeutics

It is not understood why healthy tissues can exhibit varying levels of sensitivity to the same toxic stimuli. Using BH3 profiling, we find that mitochondria of many adult somatic tissues, including brain, heart, and kidneys, are profoundly refractory to pro-apoptotic signaling, leading to cellular resistance to cytotoxic chemotherapies and ionizing radiation. In contrast, mitochondria from these tissues in young mice and humans are primed for apoptosis, predisposing them to undergo cell death in response to genotoxic damage. While expression of the apoptotic protein machinery is nearly absent by adulthood, in young tissues its expression is driven by c-Myc, linking developmental growth to cell death. These differences may explain why pediatric cancer patients have a higher risk of developing treatment-associated toxicities

Revolatilisation of soil-accumulated pollutants triggered by the summer monsoon in India

Persistent organic pollutants that have accumulated in soils can be remobilised by volatilisation in response to chemical equilibrium with the atmosphere. Clean air masses from the Indian Ocean, advected with the onset of the summer monsoon, are found to reduce concentrations of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its derivatives, endosulfan and polychlorinated biphenyls (PCBs) in air at a mountain site (all in the range 5–20&thinsp;pg&thinsp;m−3) by 77&thinsp;%, 70&thinsp;%, 82&thinsp;% and 45&thinsp;%, respectively. The analysis of fugacities in soil and air suggest that the arrival of summer monsoon triggers net volatilisation or enhances ongoing revolatilisation of the now-banned chemicals HCH and PCBs from background soils in southern India. The response of the air–soil exchange was modelled using a regional air pollution model, WRF-Chem PAH/POP. The results suggest that the air is increasingly polluted during transport by the south-westerly monsoon winds across the subcontinent. Using a multidecadal multimedia mass balance model, it is found that air–surface exchange of HCH and DDT have declined since the ban of these substances from agriculture, but remobilisation of higher chlorinated PCBs may have reached a historical high, 40 years after peak emission.</p

Hematopoietic Cell Transplantation Outcomes in Monosomal Karyotype Myeloid Malignancies

The presence of monosomal karyotype (MK+) in acute myeloid leukemia (AML) is associated with dismal outcomes. We evaluated the impact of MK+ in AML (MK+AML, N=240) and in myelodysplastic syndrome (MK+MDS, N=221) on hematopoietic cell transplantation (HCT) outcomes compared to other cytogenetically defined groups (AML, N=3,360; MDS, N=1,373) as reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) from 1998 to 2011. MK+AML was associated with higher disease relapse (hazard ratio [HR] 1.98, p<0.01), similar transplant related mortality (TRM, HR 1.01, p=0.9) and worse survival (HR 1.67, p<0.01) compared to other cytogenetically defined AML. Among patients with MDS, MK+MDS was associated with higher disease relapse (HR 2.39, p<0.01), higher TRM (HR 1.80, p<0.01) and worse survival (HR 2.02, p<0.01). Subset analyses comparing chromosome 7 abnormalities (del7/7q) with or without MK+ demonstrated higher mortality for MK+ disease in for both AML (HR 1.72, p<0.01) and MDS (HR1.79, p<0.01). The strong negative impact of MK+ in myeloid malignancies was observed in all age groups and using either myeloablative or reduced intensity conditioning regimens. Alternative approaches to mitigate disease relapse in this population are needed

Repression of the type I interferon pathway underlies MYC & KRAS-dependent evasion of NK & B cells in pancreatic ductal adenocarcinoma

MYC is implicated in the development and progression of Pancreatic cancer, yet the precise level of MYC deregulation required to contribute to tumour development has been difficult to define. We used modestly elevated expression of human MYC, driven from the Rosa26 locus, to investigate the pancreatic phenotypes arising in mice from an approximation of MYC trisomy. We show that this level of MYC alone suffices to drive pancreatic neuroendocrine tumours, and to accelerate progression of KRAS-initiated precursor lesions to metastatic pancreatic ductal adenocarcinoma. Our phenotype exposed suppression of the Type I Interferon pathway by the combined actions of MYC and KRAS and we present evidence of repressive MYC/MIZ1 complexes binding directly to the promoters of type I Interferon regulators IRF5, IRF7, STAT1 and STAT2. De-repression of Interferon regulators allows pancreatic tumour infiltration of B and NK cells, resulting in increased survival

Glutamine Anabolism Plays a Critical Role in Pancreatic Cancer by Coupling Carbon and Nitrogen Metabolism

Glutamine is thought to play an important role in cancer cells by being deaminated via glutaminolysis to alpha-ketoglutarate (aKG) to fuel the tricarboxylic acid (TCA) cycle. Supporting this notion, aKG supplementation can restore growth/survival of glutamine-deprived cells. However, pancreatic cancers are often poorly vascularized and limited in glutamine supply, in alignment with recent concerns on the significance of glutaminolysis in pancreatic cancer. Here, we show that aKG-mediated rescue of glutamine-deprived pancreatic ductal carcinoma (PDAC) cells requires glutamate ammonia ligase (GLUL), the enzyme responsible for de novo glutamine synthesis. GLUL-deficient PDAC cells are capable of the TCA cycle but defective in aKG-coupled glutamine biosynthesis and subsequent nitrogen anabolic processes. Importantly, GLUL expression is elevated in pancreatic cancer patient samples and in mouse PDAC models. GLUL ablation suppresses the development of Kras(G12D)-driven murine PDAC. Therefore, GLUL-mediated glutamine biosynthesis couples the TCA cycle with nitrogen anabolism and plays a critical role in PDAC

Improved Outcomes After Autologous Hematopoietic Cell Transplantation for Light Chain Amyloidosis: A Center for International Blood and Marrow Transplant Research Study

Autologous hematopoietic cell transplantation, or autotransplantation, is effective in light-chain amyloidosis (AL), but it is associated with a high risk of early mortality (EM). In a multicenter randomized comparison against oral chemotherapy, autotransplantation was associated with 24% EM. We analyzed trends in outcomes after autologous hematopoietic cell transplantation for AL in North America