bay-11-7082 and Necrosis

Cadmium (Cd), a toxic heavy metal and carcinogen that is abundantly present in cigarette smoke, is a cause of smoking-induced lung disease. SLC39A8 (ZIP8), a zinc transporter, is a major portal for Cd uptake into cells. We have recently identified that ZIP8 expression is under the transcriptional control of the NF-κB pathway. On the basis of this, we hypothesized that cigarette-smoke induced inflammation would increase ZIP8 expression in lung epithelia, thereby enhancing Cd uptake and cell toxicity. Herein we report that ZIP8 is a central mediator of Cd-mediated toxicity. TNF-α treatment of primary human lung epithelia and A549 cells induced ZIP8 expression, resulting in significantly higher cell death attributable to both apoptosis and necrosis following Cd exposure. Inhibition of the NF-κB pathway and ZIP8 expression significantly reduced cell toxicity. Zinc (Zn), a known cytoprotectant, prevented Cd-mediated cell toxicity via ZIP8 uptake. Consistent with cell culture findings, a significant increase in ZIP8 mRNA and protein expression was observed in the lung of chronic smokers compared with nonsmokers. From these studies, we conclude that ZIP8 expression is induced in lung epithelia in an NF-κB-dependent manner, thereby resulting in increased cell death in the presence of Cd. From this we contend that ZIP8 plays a critical role at the interface between micronutrient (Zn) metabolism and toxic metal exposure (Cd) in the lung microenvironment following cigarette smoke exposure. Furthermore, dietary Zn intake, or a lack thereof, may be a contributing factor in smoking-induced lung disease.

Topics: Apoptosis; Cadmium; Cation Transport Proteins; Cell Line; Cell Polarity; Cytoprotection; Epithelial Cells; Humans; Lung; Necrosis; NF-kappa B; Nitriles; Primary Cell Culture; Pulmonary Disease, Chronic Obstructive; Smoking; Sulfones; Transcriptional Activation; Tumor Necrosis Factor-alpha; Up-Regulation; Zinc

Intercellular adhesion molecule-1 (ICAM-1) expression has been detected in melanocytes around active vitiligo patches as well as in surgically transplanted melanocytes. However, it is unclear whether and how skin injury induces the inappropriate expression of ICAM-1 and other proinflammatory genes in melanocytes. We previously reported that human melanocytes expressed TLR3. We hypothesized that the TLR3 expressed in melanocytes may recognize skin injury by binding to the endogenous ligands secreted by the damaged keratinocytes. Here we showed that RNA released from necrotic keratinocytes induced the upregulation of ICAM-1 protein and mRNA, as shown by FACS and real-time RT-PCR. Use of NF-κB inhibitor prevents upregulation of ICAM-1 in melanocytes indicating a direct role of NF-κB in necrotic keratinocyte-mediated upregulation of ICAM-1. Using a shRNA-expressing lentivirus, we demonstrated that in human melanocytes, TLR3 seems to be necessary for the upregulation of ICAM-1. Using oligonucleotide microarray, we demonstrated a dramatic increase in proinflammatory cytokine and chemokine transcripts (CXCL10, CXCL11, TNFSF10, CCL5, CCL4, CCL2, IFNB1, CCL20, IL-8, and CCL11). These observations suggested that RNA released from necrotic keratinocytes might act as an endogenous TLR3 ligand for the stimulation of ICAM-1 and other proinflammatory gene expression in human melanocytes, which might be involved in the pathogenesis of vitiligo following skin physical trauma.

Topics: Cell Communication; Cytokines; Humans; Inflammation Mediators; Intercellular Adhesion Molecule-1; Keratinocytes; Melanocytes; Necrosis; NF-kappa B; Nitriles; Oligonucleotide Array Sequence Analysis; RNA; RNA, Small Interfering; Sulfones; Toll-Like Receptor 3; Ultraviolet Rays; Up-Regulation; Vitiligo

We determined how CXC-chemokine signalling and necrosis factor-kappaB (NF-kappaB) activity affected heat-shock protein 90 (Hsp90) inhibitor (geldanamycin (GA) and 17-allylamino-demethoxygeldanamycin (17-AAG)) cytotoxicity in castrate-resistant prostate cancer (CRPC).. Geldanamycin and 17-AAG toxicity, together with the CXCR2 antagonist AZ10397767 or NF-kappaB inhibitor BAY11-7082, was assessed by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay in two CRPC lines, DU145 and PC3. Flow cytometry quantified apoptotic or necrosis profiles. Necrosis factor-kappaB activity was determined by luciferase readouts or indirectly by quantitative PCR and ELISA-based determination of CXCL8 expression.. Geldanamycin and 17-AAG reduced PC3 and DU145 cell viability, although PC3 cells were less sensitive. Addition of AZ10397767 increased GA (e.g., PC3 IC(20): from 1.67+/-0.4 to 0.18+/-0.2 nM) and 17-AAG (PC3 IC(20): 43.7+/-7.8 to 0.64+/-1.8 nM) potency in PC3 but not DU145 cells. Similarly, BAY11-7082 increased the potency of 17-AAG in PC3 but not in DU145 cells, correlating with the elevated constitutive NF-kappaB activity in PC3 cells. AZ10397767 increased 17-AAG-induced apoptosis and necrosis and decreased NF-kappaB activity/CXCL8 expression in 17-AAG-treated PC3 cells.. Ansamycin cytotoxicity is enhanced by inhibiting NF-kappaB activity and/or CXC-chemokine signalling in CRPC cells. Detecting and/or inhibiting NF-kappaB activity may aid the selection and treatment response of CRPC patients to Hsp90 inhibitors.

Topics: Apoptosis; Benzoquinones; Cell Line, Tumor; Cell Survival; HSP90 Heat-Shock Proteins; Humans; Interleukin-8; Lactams, Macrocyclic; Male; Necrosis; NF-kappa B; Nitriles; Orchiectomy; Prostatic Neoplasms; Receptors, Interleukin-8B; Rifabutin; Signal Transduction; Sulfones