Although poorly understood, normal cells and cancerous cells of the same type exhibit different patterns of nutrient consumption, processing and utility of metabolic substrates. Differences in substrate uptake, preference, and alternately emphasized metabolic pathways offer opportunities for selective targeting of cancer versus stroma. This may be accomplished by using a sequential approach of nutrient deprivation and pharmaceutical perturbation of metabolic pathways to inhibit cellular proliferation. The purpose of this study was to investigate the effects of restricting glucose and glutamine concentrations, in vitro, to levels that resemble a potential human fasting state. The mammalian target of rapamycin (mTOR), a mediator of nutrient sensation, was then inhibited with rapamycin in the nutrient-restricted conditions. Because active Akt/mTOR is implicated in cancer cell pro-survival, the hypothesis is that pharmaceutical inhibition of active Akt/mTOR signaling in combination with the stress of restricted nutrient supply will be more effective than nutrient deprivation alone at disrupting metabolic processes to impair cancer cell proliferation and/or pro-survival mechanisms. Untreated and treated conditions were tested to determine if an additive or synergistic effect would result from a sequential insult of nutrient deprivation followed by inhibited mTORC1 signaling. The cell line used for this study was cultivated from a murine pancreatic intraepithelial neoplasia (PANIN) derived from a transgenic mouse with pancreatic tissue-specific expression of constitutively active Akt. The transgene of Akt, isoform 1, contains a myristoyl tag that facilitates co-localization of Akt to the plasma membrane, thereby promoting the activation of this signaling protein.; This aberrantly activated Akt represents a prosurvival condition observed in most cancers, and impacts metabolic balance with increased downstream signaling to metabolic sensors and regulators, including mTORC1. Several methods were used to evaluate changes in metabolic and physiological response to nutrient deprivation and mTORC1 inhibition. These included tetrazolium reduction/absorbance readings to qualitatively evaluate differences in cell proliferation, and Western immunoblots for observing changes in protein expression and phosphorylation. ATP luminescence assays were applied to quantify intracellular ATP content, and citrate synthase spectrophotometry used to quantify specific activity/indicate changes in the TCA/OXPHOS production of ATP. Results from the above methods suggest that, individually, nutrient deprivation and rapamycin treatment share some similar effects on metabolically-related protein phosphorylation and in reducing cellular proliferation. Collectively, nutrient deprivation plus rapamycin treatment, however, resulted in unanticipated metabolic alterations under conditions used for this study, the complexities of which would need to be delineated in future studies.

Acute myeloid leukemia (AML) develops following oncogenic alterations to hematopoietic stem (HSC) and progenitor cells (HSPCs) in the bone marrow, resulting in dysregulated proliferation of immature myeloid progenitors that interferes with normal hematopoiesis. Understanding the mechanisms of HSPC protection against damage and excessive division, and how these pathways are altered during leukemic progression, is vital for establishing effective therapies. Here, we show that autophagy, a lysosomal degradation pathway, is increased in HSPCs using a novel imaging flow cytometry autophagy assay. Loss of hematopoietic autophagy following deletion of key gene Atg5 resulted in increased HSC proliferation, leading to HSC exhaustion and bone marrow failure. Although erythrocyte and lymphocyte populations were negatively impacted by autophagy loss, myeloid cells showing immature characteristics were expanded. Deletion of Atg5 in an AML model resulted in increased proliferation under metabolic stress, dependent on the glycolytic pathway, and aberrant upstream mTOR signaling. Moreover, modulation of Atg5 altered leukemic response to culture with stromal cells. Finally, primary AML cells displayed multiple markers of decreased autophagy. These data suggest a role for autophagy in preserving HSC function, partially through suppression of HSPC proliferation, and indicate that decreased autophagy may benefit AML cells. We postulate that modulation of autophagy could help maintain stem cell function, for example during transplantation, and aid AML therapy in a setting-specific manner.

Sepsis é uma disfunção de órgãos causada por uma resposta desregulada do hospedeiro em decorrência de uma infecção e que eventualmente leva a morte. A identificação de moléculas que minimizem este processo pode fornecer alvos terapêuticos para prevenir a falência de órgãos durante a sepse. O supressor de sinalização de citocinas 1 (SOCS1) é conhecido por regular negativamente a sinalização de receptores de citocinas e de receptores do tipo Toll (TLRs). No entanto, os alvos celulares e mecanismos moleculares envolvidos nas ações de SOCS1 durante a sepse são desconhecidos. Para determinar o papel de SOCS1 durante a sepse polimicrobiana, camundongos C57BL/6 foram tratados com um peptídeo inibidor do domínio KIR (kinase inhibitor region) do SOCS1 (iKIR) e submetidos à CLP (ligação e perfusão do ceco). O tratamento com iKIR aumentou a mortalidade, a carga bacteriana e a produção de citocinas inflamatórias induzida pela CLP. Além disso, observou-se que animais deficientes de SOCS1 nas células mielóides (SOCS1?myel) também tiveram aumento na carga bacteriana e na produção de citocinas proinflamatórias, quando comparados com camundongos SOCS1fl. O aumento na susceptibilidade a sepse foi acompanhado pelo aumento da via glicolítica nas células peritoneias e no pulmão desses animais. Assim, foi observado aumento da produção de ácido láctico e da expressão de enzimas glicolíticas como hexoquinase-1 (Hk1), lactato desidrogenase A (Ldha) e o transportador de glicose 1 (Glut-1) em camundongos sépticos tratados com iKIR ou SOCS1?myel. A expressão desses genes da via glicolítica foi dependente da via de ativação STAT3/HIF-1?. O tratamento com 2-deoxiglicose (inibidor da via glicolítica) diminuiu a susceptibilidade à sepse em camundongos tratados com iKIR. Estes resultados indicam um papel até agora desconhecido de SOCS1, como um regulador de reprogramação metabólica que reduz a resposta inflamatória exacerbada e o dano de órgãos durante a sepse. / Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Identification of pleiotropic molecular brakes might provide therapeutic targets to prevent organ failure during sepsis. Suppressor of cytokine signaling 1 (SOCS1) is known to negatively regulate signaling by cytokine and Tolllike receptors (TLRs). However, the cellular targets and molecular mechanisms involved in SOCS1 actions during sepsis are unknown. To address this in a cecal ligation puncture (CLP) model of sepsis, we treated C57BL/6 mice with an antagonist peptide (iKIR) that blocks the kinase inhibitory region (KIR) domain of SOCS1 and prevents its actions. iKIR treatment increased mortality, bacterial burden and inflammatory cytokine production induced after CLP. We also found that myeloid cell-specific SOCS1 deletion (SOCS1?myel) rendered mice more susceptible to sepsis, shown by higher bacterial loads and inflammatory cytokines than SOCS1fl littermate control mice. O aumento na susceptibilidade a sepse foi acompanhado pelo aumento da via glicolítica nas células peritoneias e pulmão desses animais. These effects were accompanied by increase of glycolysis function in peritoneal cells and lung of SOCS1?myel. Thus, it was observed increased expression of the glycolytic enzymes, hexoquinase-1 (Hk1), lactate dehydrogenase A (Ldha), and glucose transporter 1 (Glut-1) in iKIR-treated or SOCS1?myel septic mice. These events were dependent on the activation of STAT3/HIF-1? pathway. Blocking glycolysis with 2-deoxyglucose ameliorated the increased susceptibility to sepsis in iKIR-treated CLP mice. Together, we unveiled a heretofore unknown role of SOCS1 as a regulator of metabolic reprograming that reduces overwhelming inflammatory response and organ damage during sepsis.

Sepsis é uma disfunção de órgãos causada por uma resposta desregulada do hospedeiro em decorrência de uma infecção e que eventualmente leva a morte. A identificação de moléculas que minimizem este processo pode fornecer alvos terapêuticos para prevenir a falência de órgãos durante a sepse. O supressor de sinalização de citocinas 1 (SOCS1) é conhecido por regular negativamente a sinalização de receptores de citocinas e de receptores do tipo Toll (TLRs). No entanto, os alvos celulares e mecanismos moleculares envolvidos nas ações de SOCS1 durante a sepse são desconhecidos. Para determinar o papel de SOCS1 durante a sepse polimicrobiana, camundongos C57BL/6 foram tratados com um peptídeo inibidor do domínio KIR (kinase inhibitor region) do SOCS1 (iKIR) e submetidos à CLP (ligação e perfusão do ceco). O tratamento com iKIR aumentou a mortalidade, a carga bacteriana e a produção de citocinas inflamatórias induzida pela CLP. Além disso, observou-se que animais deficientes de SOCS1 nas células mielóides (SOCS1?myel) também tiveram aumento na carga bacteriana e na produção de citocinas proinflamatórias, quando comparados com camundongos SOCS1fl. O aumento na susceptibilidade a sepse foi acompanhado pelo aumento da via glicolítica nas células peritoneias e no pulmão desses animais. Assim, foi observado aumento da produção de ácido láctico e da expressão de enzimas glicolíticas como hexoquinase-1 (Hk1), lactato desidrogenase A (Ldha) e o transportador de glicose 1 (Glut-1) em camundongos sépticos tratados com iKIR ou SOCS1?myel. A expressão desses genes da via glicolítica foi dependente da via de ativação STAT3/HIF-1?. O tratamento com 2-deoxiglicose (inibidor da via glicolítica) diminuiu a susceptibilidade à sepse em camundongos tratados com iKIR. Estes resultados indicam um papel até agora desconhecido de SOCS1, como um regulador de reprogramação metabólica que reduz a resposta inflamatória exacerbada e o dano de órgãos durante a sepse. / Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Identification of pleiotropic molecular brakes might provide therapeutic targets to prevent organ failure during sepsis. Suppressor of cytokine signaling 1 (SOCS1) is known to negatively regulate signaling by cytokine and Tolllike receptors (TLRs). However, the cellular targets and molecular mechanisms involved in SOCS1 actions during sepsis are unknown. To address this in a cecal ligation puncture (CLP) model of sepsis, we treated C57BL/6 mice with an antagonist peptide (iKIR) that blocks the kinase inhibitory region (KIR) domain of SOCS1 and prevents its actions. iKIR treatment increased mortality, bacterial burden and inflammatory cytokine production induced after CLP. We also found that myeloid cell-specific SOCS1 deletion (SOCS1?myel) rendered mice more susceptible to sepsis, shown by higher bacterial loads and inflammatory cytokines than SOCS1fl littermate control mice. O aumento na susceptibilidade a sepse foi acompanhado pelo aumento da via glicolítica nas células peritoneias e pulmão desses animais. These effects were accompanied by increase of glycolysis function in peritoneal cells and lung of SOCS1?myel. Thus, it was observed increased expression of the glycolytic enzymes, hexoquinase-1 (Hk1), lactate dehydrogenase A (Ldha), and glucose transporter 1 (Glut-1) in iKIR-treated or SOCS1?myel septic mice. These events were dependent on the activation of STAT3/HIF-1? pathway. Blocking glycolysis with 2-deoxyglucose ameliorated the increased susceptibility to sepsis in iKIR-treated CLP mice. Together, we unveiled a heretofore unknown role of SOCS1 as a regulator of metabolic reprograming that reduces overwhelming inflammatory response and organ damage during sepsis.