Mitochondrial DNA mutations are involved in the acquisition of cisplatin resistance in human lung cancer A549 cells.

The efficacy of cisplatin (CDDP) has been demonstrated in the treatment of various cancers as monotherapy and combination therapy with immunotherapy. However, acquired CDDP resistance is a major obstacle to successful treatment. In the present study, the mechanisms underlying acquired CDDP resistance were examined using ACR20 cells, which are CDDP­resistant cells derived from A549 lung cancer cells. CDDP induces cytotoxicity by binding nuclear DNA and generating reactive oxygen species (ROS). Contrary to our expectation, ROS levels were elevated in ACR20 cells not treated with CDDP. Pretreatment with an ROS inhibitor enhanced the sensitivity of ACR20 cells to CDDP and prevented the activation of nuclear factor (NF)­ÐºB signaling and upregulation of inhibitor of apoptosis proteins (IAPs). Notably, evaluation of the mitochondrial oxygen consumption rate and mitochondrial superoxide levels revealed a deterioration of mitochondrial function in ACR20 cells. Mitochondrial DNA PCR­RFLP analysis revealed four mutations with varying percentage levels in ACR20 cells. In addition, in cytoplasmic hybrids with mitochondria from ACR20 cells, intrinsic ROS levels were elevated, expression of IAPs was increased, and complex I activity and sensitivity to CDDP were decreased. Analysis of three­dimensional structure data indicated that a mutation (ND2 F40L) may impact the proton translocation pathway, thereby affecting mitochondrial complex I activity. Together, these findings suggest that intrinsic ROS levels were elevated by mitochondrial DNA mutations, which decreased the sensitivity to CDDP via activation of NF­κB signaling and induction of IAP expression in ACR20 cells. These findings indicate that newly identified mutations in mitochondrial DNA may lead to acquired cisplatin resistance in cancer.

Cell Cycle Perturbation Induces Collagen Production in Fibroblasts.

Myocardial infarction (MI) occurs when the heart muscle is severely damaged due to a decrease in blood flow from the coronary arteries. During recovery from an MI, cardiac fibroblasts become activated and produce extracellular matrices, contributing to the wound healing process in the damaged heart. Inappropriate activation of the fibroblasts leads to excessive fibrosis in the heart. However, the molecular pathways by which cardiac fibroblasts are activated have not yet been fully elucidated.Here we show that serum deprivation, which recapitulates the cellular microenvironment of the MI area, strikingly induces collagen production in C3H/10T1/2 cells. Based on transcriptomic and pharmacological studies, we found that cell cycle perturbation is directly linked to collagen production in fibroblasts. Importantly, collagen synthesis is increased independently of the transcriptional levels of type I collagen genes. These results reveal a novel mode of fibroblast activation in the ischemic area, which will allow us to gain insights into the molecular mechanisms underlying cardiac fibrosis and establish a basis for anti-fibrotic therapy.

Macrophage hypoxia signaling regulates cardiac fibrosis via Oncostatin M.

The fibrogenic response in tissue-resident fibroblasts is determined by the balance between activation and repression signals from the tissue microenvironment. While the molecular pathways by which transforming growth factor-1 (TGF-ß1) activates pro-fibrogenic mechanisms have been extensively studied and are recognized critical during fibrosis development, the factors regulating TGF-ß1 signaling are poorly understood. Here we show that macrophage hypoxia signaling suppresses excessive fibrosis in a heart via oncostatin-m (OSM) secretion. During cardiac remodeling, Ly6Chi monocytes/macrophages accumulate in hypoxic areas through a hypoxia-inducible factor (HIF)-1α dependent manner and suppresses cardiac fibroblast activation. As an underlying molecular mechanism, we identify OSM, part of the interleukin 6 cytokine family, as a HIF-1α target gene, which directly inhibits the TGF-ß1 mediated activation of cardiac fibroblasts through extracellular signal-regulated kinase 1/2-dependent phosphorylation of the SMAD linker region. These results demonstrate that macrophage hypoxia signaling regulates fibroblast activation through OSM secretion in vivo.

Pyruvate Dehydrogenase PDH-E1ß Controls Tumor Progression by Altering the Metabolic Status of Cancer Cells.

Downregulation of pyruvate dehydrogenase (PDH) is critical for the aberrant preferential activation of glycolysis in cancer cells under normoxic conditions. Phosphorylation-dependent inhibition of PDH is a relevant event in this process, but it is not durable as it relies on PDH kinases that are activated ordinarily under hypoxic conditions. Thus, it remains unclear how PDH is durably downregulated in cancer cells that are not hypoxic. Building on evidence that PDH activity depends on the stability of a multi-protein PDH complex, we found that the PDH-E1ß subunit of the PDH complex is downregulated to inhibit PDH activity under conditions of prolonged hypoxia. After restoration of normoxic conditions, reduced expression of PDH-E1ß was sustained such that glycolysis remained highly activated. Notably, PDH-E1ß silencing in cancer cells produced a metabolic state strongly resembling the Warburg effect, but inhibited tumor growth. Conversely, enforced exogenous expression of PDH-E1ß durably increased PDH activity and promoted the malignant growth of breast cancer cells in vivo Taken together, our results establish the specific mechanism through which PDH acts as an oncogenic factor by tuning glycolytic metabolism in cancer cells.Significance: This seminal study offers a mechanistic explanation for why glycolysis is aberrantly activated in normoxic cancer cells, offering insights into this long-standing hallmark of cancer termed the Warburg effect. Cancer Res; 78(7); 1592-603. ©2018 AACR.

Mitochondrial Abnormality Facilitates Cyst Formation in Autosomal Dominant Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease (ADPKD) constitutes the most inherited kidney disease. Mutations in the PKD1 and PKD2 genes, encoding the polycystin 1 and polycystin 2 Ca2+ ion channels, respectively, result in tubular epithelial cell-derived renal cysts. Recent clinical studies demonstrate oxidative stress to be present early in ADPKD. Mitochondria comprise the primary reactive oxygen species source and also their main effector target; however, the pathophysiological role of mitochondria in ADPKD remains uncharacterized. To clarify this function, we examined the mitochondria of cyst-lining cells in ADPKD model mice (Ksp-Cre PKD1flox/flox) and rats (Han:SPRD Cy/+), demonstrating obvious tubular cell morphological abnormalities. Notably, the mitochondrial DNA copy number and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) expression were decreased in ADPKD model animal kidneys, with PGC-1α expression inversely correlated with oxidative stress levels. Consistent with these findings, human ADPKD cyst-derived cells with heterozygous and homozygous PKD1 mutation exhibited morphological and functional abnormalities, including increased mitochondrial superoxide. Furthermore, PGC-1α expression was suppressed by decreased intracellular Ca2+ levels via calcineurin, p38 mitogen-activated protein kinase (MAPK), and nitric oxide synthase deactivation. Moreover, the mitochondrion-specific antioxidant MitoQuinone (MitoQ) reduced intracellular superoxide and inhibited cyst epithelial cell proliferation through extracellular signal-related kinase/MAPK inactivation. Collectively, these results indicate that mitochondrial abnormalities facilitate cyst formation in ADPKD.

The distinct metabolic phenotype of lung squamous cell carcinoma defines selective vulnerability to glycolytic inhibition.

Adenocarcinoma (ADC) and squamous cell carcinoma (SqCC) are the two predominant subtypes of non-small cell lung cancer (NSCLC) and are distinct in their histological, molecular and clinical presentation. However, metabolic signatures specific to individual NSCLC subtypes remain unknown. Here, we perform an integrative analysis of human NSCLC tumour samples, patient-derived xenografts, murine model of NSCLC, NSCLC cell lines and The Cancer Genome Atlas (TCGA) and reveal a markedly elevated expression of the GLUT1 glucose transporter in lung SqCC, which augments glucose uptake and glycolytic flux. We show that a critical reliance on glycolysis renders lung SqCC vulnerable to glycolytic inhibition, while lung ADC exhibits significant glucose independence. Clinically, elevated GLUT1-mediated glycolysis in lung SqCC strongly correlates with high 18F-FDG uptake and poor prognosis. This previously undescribed metabolic heterogeneity of NSCLC subtypes implicates significant potential for the development of diagnostic, prognostic and targeted therapeutic strategies for lung SqCC, a cancer for which existing therapeutic options are clinically insufficient.

HIF-1α-PDK1 axis-induced active glycolysis plays an essential role in macrophage migratory capacity.

In severely hypoxic condition, HIF-1α-mediated induction of Pdk1 was found to regulate glucose oxidation by preventing the entry of pyruvate into the tricarboxylic cycle. Monocyte-derived macrophages, however, encounter a gradual decrease in oxygen availability during its migration process in inflammatory areas. Here we show that HIF-1α-PDK1-mediated metabolic changes occur in mild hypoxia, where mitochondrial cytochrome c oxidase activity is unimpaired, suggesting a mode of glycolytic reprogramming. In primary macrophages, PKM2, a glycolytic enzyme responsible for glycolytic ATP synthesis localizes in filopodia and lammelipodia, where ATP is rapidly consumed during actin remodelling processes. Remarkably, inhibition of glycolytic reprogramming with dichloroacetate significantly impairs macrophage migration in vitro and in vivo. Furthermore, inhibition of the macrophage HIF-1α-PDK1 axis suppresses systemic inflammation, suggesting a potential therapeutic approach for regulating inflammatory processes. Our findings thus demonstrate that adaptive responses in glucose metabolism contribute to macrophage migratory activity.

A case of hypertrophic obstructive cardiomyopathy and acquired von Willebrand syndrome: response to medical therapy.

Heyde's syndrome is the combined occurrence of acquired von Willebrand disease caused by aortic valve stenosis and gastrointestinal bleeding that occurs particularly in elderly patients. The bleeding may be linked to the intravascular shear-induced proteolysis of high-molecular-weight multimers (HMWMs) of von Willebrand factor (vWF). Hypertrophic obstructive cardiomyopathy (HOCM) in the left ventricular outflow tract generates a high shear stress condition that can induce such proteolysis. We report the case of a 70-year-old woman with HOCM who had severe anemia and loss of HMWMs. After reduction of the outflow gradient by medical treatment, vWF normalized, and her anemia alleviated.

Fatal septicemia and endotoxic shock due to Aeromonas hydrophila.

BACKGROUND: Although rare, bloodstream infections caused by Aeromonas tend to be very severe and progress rapidly. CASE REPORT: We report a case of an 81-year-old man with fetal septicemia and endotoxin shock caused by Aeromonas hydrophila. The patient had dilated cardiomyopathy, paroxysmal atrial fibrillation, interstitial pneumonitis and renal dysfunction was admitted to our hospital with chest pain and dyspnea. Transthoracic echocardiography demonstrated impaired left ventricular wall motion and severe mitral regurgitation due to tethering. Cardiac catheterization revealed severe stenotic lesions in the left anterior descending artery and the right coronary artery. Surgery for coronary artery bypass grafts and mitral annuloplasty were performed. However, 2 days after surgery, he suddenly developed a high-grade fever and his hemodynamics deteriorated rapidly. His blood cultures revealed gram-negative Bacillus and the endotoxin concentration in the blood was elevated. Despite intensive support efforts, the patient died 1 day after the sudden change. His blood culture revealed A. hydrophila. CONCLUSIONS: Whenever Aeromonas is found in a patient's bloodstream, clinicians should start appropriate and intensive treatment immediately.