Germline mutation in serine/threonine kinase 11 (STK11, also called LKB1) results in Peutz-Jeghers syndrome, characterized by intestinal hamartomas and increased incidence of epithelial cancers. Although uncommon in most sporadic cancers, inactivating somatic mutations of LKB1 have been reported in primary human lung adenocarcinomas and derivative cell lines. Here we used a somatically activatable mutant Kras-driven model of mouse lung cancer to compare the role of Lkb1 to other tumour suppressors in lung cancer. Although Kras mutation cooperated with loss of p53 or Ink4a/Arf (also known as Cdkn2a) in this system, the strongest cooperation was seen with homozygous inactivation of Lkb1. Lkb1-deficient tumours demonstrated shorter latency, an expanded histological spectrum (adeno-, squamous and large-cell carcinoma) and more frequent metastasis compared to tumours lacking p53 or Ink4a/Arf. Pulmonary tumorigenesis was also accelerated by hemizygous inactivation of Lkb1. Consistent with these findings, inactivation of LKB1 was found in 34% and 19% of 144 analysed human lung adenocarcinomas and squamous cell carcinomas, respectively. Expression profiling in human lung cancer cell lines and mouse lung tumours identified a variety of metastasis-promoting genes, such as NEDD9, VEGFC and CD24, as targets of LKB1 repression in lung cancer. These studies establish LKB1 as a critical barrier to pulmonary tumorigenesis, controlling initiation, differentiation and metastasis.

The EGFR T790M mutation has been identified in tumors from lung cancer patients that eventually develop resistance to erlotinib. In this study, we generated a mouse model with doxycycline-inducible expression of a mutant EGFR containing both L858R, an erlotinib-sensitizing mutation, and the T790M resistance mutation (EGFR TL). Expression of EGFR TL led to development of peripheral adenocarcinomas with bronchioloalveolar features in alveoli as well as papillary adenocarcinomas in bronchioles. Treatment with an irreversible EGFR tyrosine kinase inhibitor (TKI), HKI-272, shrunk only peripheral tumors but not bronchial tumors. However, the combination of HKI-272 and rapamycin resulted in significant regression of both types of lung tumors. This combination therapy may potentially benefit lung cancer patients with the EGFR T790M mutation.

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Mutations in the BRAF and KRAS genes occur in f1% to 2% and 20% to 30% of non-small-cell lung cancer patients, respectively, suggesting that the mitogen-activated protein kinase (MAPK) pathway is preferentially activated in lung cancers. Here, we show that lung-specific expression of the BRAF V600E mutant induces the activation of extracellular signal-regulated kinase (ERK)-1/2 (MAPK) pathway and the development of lung adenocarcinoma with bronchioloalveolar carcinoma features in vivo. Deinduction of transgene expression led to dramatic tumor regression, paralleled by dramatic dephosphorylation of ERK1/2, implying a dependency of BRAF-mutant lung tumors on the MAPK pathway.

Background: Tumor mutational burden (TMB) is a potential biomarker for immune checkpoint therapy and prognosis. The impact of TMB on clinical outcomes and the correlation coefficient between exome sequencing and targeted sequencing in glioma have not yet been explored. Methods: Somatic mutations in the coding regions of 897 primary gliomas and the clinical and RNA-seq data of 654 patients in The Cancer Genome Atlas (TCGA) database were analyzed as a training set, while another 286 patients in the Chinese Glioma Genome Atlas (CGGA) database were used for validation. Descriptive and correlational analyses were conducted with TMB. Enrichment map analysis and gene set enrichment analysis (GSEA) were also performed. Results: TMB was higher for the group of mutant genes that are frequently mutated in glioblastomas (GBMs) and lower for the group of mutant genes that are frequently mutated in lower-grade gliomas (LGGs). Patients with a higher TMB exhibited shorter overall survival. TMB was associated with grade, age, subtype and mutations affecting genomic structure. Moreover, univariate and multivariate analyses showed that TMB was an independent prognostic factor for glioma. The signaling pathways of the cell cycle were enriched in the TMB High group. TMB was higher in the mismatch repair (MMR) gene mutant group than in the wild-type group, but the MMR pathway was enriched in the TMB High group of gliomas without mutations in classical MMR genes. The correlation between TMBs calculated through exome sequencing and targeted sequencing was moderate, and panel-based TMB was not correlated with prognosis. Conclusions: TMB is associated with poor outcomes in diffuse glioma. The high proliferative activity in the TMB High group could account for the shorter survival of these patients. This association was not reflected by a pan-cancer targeted sequencing panel.

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The type 2 inositol 1,4,5-trisphosphate receptor (InsP 3 R2) was identified previously as the predominant isoform in cardiac ventricular myocytes. Here we reported the subcellular localization of InsP 3 R2 to the cardiomyocyte nuclear envelope (NE). The other major known endo/sarcoplasmic reticulum calcium-release channel (ryanodine receptor) was not localized to the NE, indicating functional segregation of these channels and possibly a unique role for InsP 3 R2 in regulating nuclear calcium dynamics. The inositol 1,4,5-trisphosphate receptor (InsP 3 R) 1 family of calcium-release channels occupies a central role in the initiation and propagation of intracellular calcium release events. These release events regulate a plethora of cellular signaling processes (reviewed in Ref. 1). The type 2 InsP 3 R (InsP 3 R2) isoform has been identified previously as the predominant isoform expressed in ventricular and atrial cardiomyocytes (2-4). Characterization of InsP 3 R2 channels from ventricular myocytes in planar lipid bilayers revealed that the permeation properties are very similar to the type 1 receptor (InsP 3 R1) from cerebellum but appear to be regulated differently. The InsP 3 R2 channel is more sensitive to InsP 3 compared with InsP 3 R1, and although calcium-dependent, the channel can be fully activated by InsP 3 at a [Ca 2ϩ ] above 100 nM (5-8). InsP 3 R2 does not play a major regulatory role in global [Ca 2ϩ ] homeostasis in ventricular myocytes, and its functional significance is unclear (9). However, in atrial myocytes InsP 3 R2 has been reported to be localized to junctional SR and may participate in arrhythmogenesis (10, 11). For example, calcium released by atrial InsP 3 may trigger calcium-induced calcium release via RyR, thereby accentuating calcium oscillations (11).A role for InsP 3 R in cardiac dysfunction has been suggested by alterations in expression levels of the failing heart in which there appears to be an up-regulation of InsP 3 R while RyR2 levels decrease (12). Also, significant evidence has been presented for the involvement of InsP 3 R in pathologies leading to calcium overload and apoptotic cardiomyocyte death, as well as implications in the pathophysiology of cardiac arrhythmia (10,13).In this study, we have identified the nuclear envelope as the primary site for subcellular localization of the type 2 InsP 3 R in ventricular myocytes. This highly localized expression may support the functional encoding of InsP 3 -mediated calcium release in calcium-dependent nuclear specific signaling. Consistent with this view, immunoprecipitation experiments revealed that the type 2 InsP 3 R in isolated cardiac nuclei associates with Ca 2ϩ /calmodulin-dependent protein kinase II (CaMKII). Coexpression of CaMKII␦ B and InsP 3 R2 followed by immunoprecipitation verifies the interaction and that the InsP 3 R2 is phosphorylated by CaMKII. Additionally, CaMKII-mediated phosphorylation of InsP 3 R2 results in a dramatic decline in channel open probability, suggesting a feedback mechanism. MATERIALS AND...

Exposure to ambient particulate matter (PM) air pollution has been reported to trigger inflammation and thrombosis. However, molecular mechanisms underlying the modulation of coagulation pathways in PM-induced thrombosis remain largely unknown. We report here that Sirt1, a member of class III histone deacetylase, controls lung inflammation and coagulation after PM exposure. Sirt1 knock-out mice exhibited aggravated lung vascular leakage and inflammation after PM exposure, which was correlated with increased NF-B acetylation and activation. Furthermore, Sirt1 knock-out mice were highly susceptible to PM-induced lung coagulation as demonstrated by increased fibrin formation. The increased fibrin formation was associated with reduced tissue factor pathway inhibitor (TFPI) expression and increased plasminogen activator inhibitor-1 (PAI-1) activity in the lungs, thus favoring elevated coagulation and disrupted fibrinolysis responses. Thrombomodulin (TM), a central player of the anticoagulant protein C system, is regulated by Kruppel-like factor 2 (KLF2) at the transcriptional level. IntroductionExposure to ambient particulate matter (PM) air pollution has been associated with impaired pulmonary function and increased cardiovascular disease-related mortality including inflammation and thrombosis. 1-5 Acute exposure to increased ambient fine particulate matter Ͻ 2.5 m in diameter (PM 2.5 ) was estimated to cause the premature deaths of tens of thousands of people each year in the United States. 6 Urban particulate matter (UPM) PM 2.5, one of the major air pollutants closely monitored by the US Environmental Protection Agency (EPA), is a complex mixture of substances that are directly emitted into the air from dust, soot, smoke, and combustion. 6 To protect public health, the EPA issued the current 24-hour PM 2.5 standard at 35 g/m 3 . 6 Despite the enormous health problems caused by PM 2.5 exposure, there have been few studies performed to explore the molecular mechanisms of PM 2.5 -induced lung vascular dysfunction. PM 2.5 can reach deep in the lung to the small airway and alveoli, 6 and directly cause lung inflammation and injury. [7][8][9][10][11][12][13] The pulmonary complications may lead to detrimental effects on other organs, particularly cardiovascular dysfunction such as systemic microvascular dysfunction and thrombosis. 1,2,4,5,13 A recent study demonstrated that short-term UPM exposure triggered the activation of primary hemostasis in healthy mice, with no substantial secondary hemostasis activation, leading to arterial but not venous thrombosis. 5 Whereas another study showed that short-term UPM exposure may cause activation of coagulation responses and fibrin formation in the lung. 14 Tissue factor pathway inhibitor (TFPI) and plasminogen activator inhibitor-1 (PAI-1) play important roles in coagulation and fibrinolysis cascades, respectively. TFPI is an inhibitor of tissue factor (TF)-mediated coagulation responses. 15 PAI-1, on the other hand, is a major regulator of fibrinolysis, which functions by in...