No abstract

Mutations in the gene encoding Bruton's tyrosine kinase (btk) cause the B cell deficiency diseases X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (xid) in mice. In vivo and in vitro studies indicate that the BTK protein is essential for B cell survival, cell cycle progression, and proliferation in response to B cell antigen receptor (BCR) stimulation. BCR stimulation leads to the activation of transcription factor nuclear factor (NF)-κB, which in turn regulates genes controlling B cell growth. We now demonstrate that a null mutation in btk known to cause the xid phenotype prevents BCR-induced activation of NF-κB. This defect can be rescued by reconstitution with wild-type BTK. This mutation also interferes with BCR-directed activation of IκB kinase (IKK), which normally targets the NF-κB inhibitor IκBα for degradation. Taken together, these findings indicate that BTK couples IKK and NF-κB to the BCR. Interference with this coupling mechanism may contribute to the B cell deficiencies observed in XLA and xid.

Many tumors increase uptake and dependence on glucose, cystine or glutamine. These basic observations on cancer cell metabolism have opened multiple new diagnostic and therapeutic avenues in cancer research. Recent studies demonstrated that smoking could induce the expression of xCT (SLC7A11) in oral cancer cells, suggesting that overexpression of xCT may support lung tumor progression. We hypothesized that overexpression of xCT occurs in lung cancer cells to satisfy the metabolic requirements for growth and survival. Our results demonstrated that 1) xCT was highly expressed at the cytoplasmic membrane in non-small cell lung cancer (NSCLC), 2) the expression of xCT was correlated with advanced stage and predicted a worse 5-year survival, 3) targeting xCT transport activity in xCT overexpressing NSCLC cells with sulfasalazine decreased cell proliferation and invasion in vitro and in vivo and 4) increased dependence on glutamine was observed in xCT overexpressed normal airway epithelial cells. These results suggested that xCT regulate metabolic requirements during lung cancer progression and be a potential therapeutic target in NSCLC.

Aberrant expression of RNA-binding proteins has profound implications for cellular physiology and the pathogenesis of human diseases such as cancer. We previously identified the Fragile X-Related 1 gene (FXR1) as one amplified candidate driver gene at 3q26-29 in lung squamous cell carcinoma (SCC). FXR1 is an autosomal paralog of Fragile X mental retardation 1 and has not been directly linked to human cancers. Here we demonstrate that FXR1 is a key regulator of tumor progression and its overexpression is critical for nonsmall cell lung cancer (NSCLC) cell growth in vitro and in vivo. We identified the mechanisms by which FXR1 executes its regulatory function by forming a novel complex with two other oncogenes, protein kinase C, iota and epithelial cell transforming 2, located in the same amplicon via distinct binding mechanisms. FXR1 expression is a candidate biomarker predictive of poor survival in multiple solid tumors including NSCLCs. Because FXR1 is overexpressed and associated with poor clinical outcomes in multiple cancers, these results have implications for other solid malignancies.

Tobacco smoking is a major risk factor for cardiovascular disease and hypertension. It is associated with the oxidative stress and induces metabolic reprogramming, altering mitochondrial function. We hypothesized that cigarette smoke induces cardiovascular mitochondrial oxidative stress, which contributes to endothelial dysfunction and hypertension. To test this hypothesis, we studied whether the scavenging of mitochondrial H2O2 in transgenic mice expressing mitochondria-targeted catalase (mCAT) attenuates the development of cigarette smoke/angiotensin II-induced mitochondrial oxidative stress and hypertension compared with wild-type mice. Two weeks of exposure of wild-type mice with cigarette smoke increased systolic blood pressure by 17 mmHg, which was similar to the effect of a subpresssor dose of angiotensin II (0.2 mg·kg−1·day−1), leading to a moderate increase to the prehypertensive level. Cigarette smoke exposure and a low dose of angiotensin II cooperatively induced severe hypertension in wild-type mice, but the scavenging of mitochondrial H2O2 in mCAT mice completely prevented the development of hypertension. Cigarette smoke and angiotensin II cooperatively induced oxidation of cardiolipin (a specific biomarker of mitochondrial oxidative stress) in wild-type mice, which was abolished in mCAT mice. Cigarette smoke and angiotensin II impaired endothelium-dependent relaxation and induced superoxide overproduction, which was diminished in mCAT mice. To mimic the tobacco smoke exposure, we used cigarette smoke condensate, which induced mitochondrial superoxide overproduction and reduced endothelial nitric oxide (a hallmark of endothelial dysfunction in hypertension). Western blot experiments indicated that tobacco smoke and angiotensin II reduce the mitochondrial deacetylase sirtuin-3 level and cause hyperacetylation of a key mitochondrial antioxidant, SOD2, which promotes mitochondrial oxidative stress. NEW & NOTEWORTHY This work demonstrates tobacco smoking-induced mitochondrial oxidative stress, which contributes to endothelial dysfunction and development of hypertension. We suggest that the targeting of mitochondrial oxidative stress can be beneficial for treatment of pathological conditions associated with tobacco smoking, such as endothelial dysfunction, hypertension, and cardiovascular diseases. Listen to this article’s corresponding podcast at https://ajpheart.podbean.com/e/mitochondrial-oxidative-stress-in-smoking-and-hypertension/ .

Signaling through the phosphatidylinositol 3-kinase (PI3-kinase) pathway has been associated with lung tumorigenesis. We examined the association between gene copy number of the PI3-kinase catalytic subunit alpha (PIK3CA) and phosphorylated Akt expression in invasive and preinvasive lung cancers. We sought to determine at what stage of tumor development gene copy number increase or phosphorylated Akt overexpression might affect tumor development. We assessed PIK3CA gene copy number by fluorescence in situ hybridization and expression of phosphorylated Akt by immunohistochemistry in 242 invasive and 43 preinvasive lung cancers and correlated our findings with clinical outcome. The PIK3CA was amplified in 70% of squamous carcinomas, 38% of large cell carcinomas, 19% of adenocarcinomas, and 67% of small cell lung cancers. Phosphorylated Akt overexpression was frequently observed, and strongly so in 12 to 17% of lung cancers depending on nuclear or cytoplasmic localization. Neither PIK3CA gene copy number nor phosphorylated Akt protein expression had prognostic significance. In preinvasive lesions, amplification of the PIK3CA and overexpression of phosphorylated Akt were associated with severe dysplasia and each other. These observations suggest frequent and early involvement of the PI3-kinase pathway in lung cancer.

Advances in proteomic analysis of human samples are driving critical aspects of biomarker discovery and the identification of molecular pathways involved in disease etiology. Toward that end, in this report we are the first to use a standardized shotgun proteomic analysis method for in-depth tissue protein profiling of the two major subtypes of nonsmall cell lung cancer and normal lung tissues. We identified 3621 proteins from the analysis of pooled human samples of squamous cell carcinoma, adenocarcinoma, and control specimens. In addition to proteins previously shown to be implicated in lung cancer, we have identified new pathways and multiple new differentially expressed proteins of potential interest as therapeutic targets or diagnostic biomarkers, including some that were not identified by transcriptome profiling. Up-regulation of these proteins was confirmed by multiple reaction monitoring mass spectrometry. A subset of these proteins was found to be detectable and differentially present in the peripheral blood of cases and matched controls. Label-free shotgun proteomic analysis allows definition of lung tumor proteomes, identification of biomarker candidates, and potential targets for therapy. Molecular & Cellular Proteomics 11: 10.1074/mcp.M111.015370, 916 -932, 2012.Lung cancer is one of the deadliest cancers, with ϳ200,000 newly diagnosed individuals and 160,000 deaths every year in the United States (1). Despite the most advanced treatments that modern medicine has to offer, the five-year survival rate remains less than 15%. Although a small subset of tumors have been found to be driven by single mutated oncogenes for which active, but still noncurative, therapies are available, the vast majority of patients have complex multifactorial disease with few effective therapeutic options. New early detection strategies and molecular therapeutic targets are urgently needed to improve patient survival.Genomic analysis has enabled us to measure the sequence, copy number, and expression changes of thousands of genes simultaneously, which can be used to discover transcripts specifically altered or expressed in tumor tissues (2-4). Although genomic studies have given important new insights into the mechanisms of carcinogenesis, therapeutic targets, and most practical biomarkers are their protein products, and the correlation between transcript sequence or level and protein function remains complex and poorly understood. Protein expression, in part, depends on transcript levels, but it is clear that significant translational and post-translational regulation of protein levels and function occurs, adding another level of complexity in the regulation of activity, especially in tumor cells (5, 6). It would be ideal to have a comprehensive understanding of the novel changes in protein expression levels and the modifications of proteins in cancer cells, but the technology to directly study proteomes has lagged behind that to assess genomes and transcriptomes. We and others have used matrix-assisted laser desorption and...

Serum from one hundred and ten breast cancer patients and thirty healthy female volunteers, were prospectively collected and evaluated for serum levels of Shh and IL-6 using human Shh and IL-6 specific enzyme-linked immunoassays. All patients were regularly monitored for event free survival (EFS) and overall survival (OS). Overall outcome analysis was based on serum Shh and IL-6 levels. In patients with progressive metastatic BC, both serum Shh and IL-6 concentrations were elevated in 44% (29 of 65) and 63% (41 of 65) of patients, respectively, at a statistically significant level [Shh (p = 0.0001) and IL-6 (p = 0.0001)] compared to the low levels in healthy volunteers. Serum levels tended to increase with metastatic progression and lymph node positivity. High serum Shh and IL-6 levels were associated with poor EFS and OS opposite to the negative or lower levels in serum Shh and IL-6. The elevated levels of both serum Shh and IL-6 were mainly observed in BC patients who had a significantly higher risk of early recurrence and bone metastasis, and associated with a worse survival for patients with progressive metastatic BC. Further studies are warranted for validating these biomarkers as prognostic tools in a larger patient cohort and in a longer follow-up study.