Proc Amer Assoc Cancer Res, Volume 46, 2005
4105
NF-κB plays a central role in regulating genes responsible for tumor cell behaviors, immunological response and inflammatory process. Development of specific inhibitors, that can block NF-κB activation, is an approach for the treatment of cancer, autoimmune and inflammatory diseases. Isodon rubescens is an herb that is commonly used in China for the treatment of patients with certain types of cancer and also for a range of inflammatory related diseases. Several diterpenoids, oridonin, ponicidin, xindongnin A and xindongnin B, were isolated from this plant. These compounds are found to be potent inhibitors of NF-κB transcription activity as well as the expression of its downstream targets, COX-2 and iNOS. This inhibitory activity could partly explain the use of this herb in Chinese medicine. The mechanisms of action of the diterpenoids against NF-κB are similar but have some differences. All the diterpenoids directly interfere with the DNA-binding activity of NF-κB to its response DNA sequence. Oridonin and ponicidin have an additional impact on the translocation of NF-κB from cytoplasm to nuclei without affecting IκB-α phosphorylation and degradation. The action of these compounds on the interaction of NF-κB with DNA sequences is unique. Different inhibitory effects on NF-κB binding to various DNA sequences were observed. Both p65:p65 and p50:p50 homodimers, as well as p65:p50 heterodimer association with their responsive DNA could be inhibited. Kinetic studies on NF-κB-DNA interaction indicate that the diterpenoids decrease the Bmax app but have no effect on Kd app . This suggests that this class of compounds interact with both p65 and p50 subunits at a site other than the DNA-binding site and subsequently modulate the binding affinity of the transcription factor towards DNA with different NF-κB binding sequences. Diterpenoids could therefore serve as a scaffold structure for the development of more potent and selective NF-κB inhibitors that target on its regulated gene transcription. (Yung-Chi Cheng is a Fellow of the National Foundation for Cancer Research.)
Introduction: Over 135 genetic loci have been linked to atrial fibrillation (AF), yet the biological pathways of AF pathophysiology remain elusive. Weighted gene coexpression network analysis (WGCNA) constructs gene modules within a network based on correlations in gene expression, and identifies mechanisms related to AF risk. Objective: To identify biological pathways of candidate AF risk genes that will advance our understanding of AF mechanisms. Methods: RNA-sequencing was performed on left atrial appendage tissue from 265 patients. RNA-seq data were adjusted for differences in AF rhythm state and other known AF risk factors. Correlations from adjusted data were further adjusted for latent factors then spatial quantile normalized to correct for mean-variance bias. WGCNA was applied to the resulting adjusted and normalized gene-gene correlations to identify gene modules. Ingenuity Pathway Analysis and gene set over representation analysis (GSOR) were applied to each module. Results: WGCNA identified 63 modules from 17,434 genes; 47 of these contained at least one candidate AF risk gene. AF risk genes were overrepresented in 7 modules (Table 1). Notable top pathways of AF overrepresented modules include apelin signaling, heme metabolism, intracellular ion homeostasis, and the unfolded protein response. These are known to be involved in calcium signaling, iron homeostasis, glucose regulation, heat shock response, and protein ubiquitination during states of high energy demand and stress. These pathways coincide with larger cellular processes of myocyte remodeling, apoptosis, and cell survival, which were also prominent. Conclusions: Biological pathways identified through WGCNA and GSOR suggest that sustained increases in energy demand during AF promotes stress-induced cellular remodeling. Changes in calcium signaling, iron homeostasis, the unfolded protein response and glucose regulation are likely primary mechanisms of AF pathophysiology.
Abstract More than 1.6 million people worldwide are diagnosed with breast cancer (BC) each year, making it the second most common form of cancer. An essential step toward a safe and effective BC therapy is to develop clinically translatable strategies to target major oncogenic drivers in BC cells. Transcription co-activators TAZ and YAP, both of which are nuclear effectors of the Hippo pathway, have recently been identified as major oncogenic drivers in BC that promote tumor propagation, metastasis and resistance to current therapies. To date, pharmacological strategies for TAZ/YAP inhibition are still lacking. Here, we successfully inhibited TAZ/YAP-driven signaling in BC models by repurposing Verteporfin, an FDA-approved drug currently used to treat neovascular macular degeneration but not human cancers. We found that Verteporfin treatment inhibited the nuclear translocation and protein expression of TAZ/YAP as well as TAZ/YAP-driven signaling (e.g. EMT signaling) in MDA-MB-231 and BT-549 breast cancer cells. Verteporfin potently inhibited cell proliferation and induced apoptotic cell death up to 90% in BC cells. Systemic Verteporfin treatment was well tolerated in mice and inhibited the growth of orthotopic tumor xenografts derived from MDA-MB-231 cells by more than 100% (p<0.01). We further characterized the molecular response of BC cells to Verteporfin using RNA-seq followed by qPCR and western blot validation. We found that Verteporfin inhibited multiple EMT marker genes (e.g. Fibronectin 1, Vimentin, Snail and Slug). In addition, Verteporfin suppressed the expression of genes that mediate BC metastasis (e.g. ANGPTL4, COX2, EREG and MMP1), and also downregulated major components of signaling pathways (e.g. Notch and Integrin) that are essential for tumorigenicity of BC cells. Some of these genes had been identified as TAZ/YAP-activated gene targets, supporting the inhibition of TAZ/YAP-driving signaling by Verteporfin. A number of novel targets were also discovered. Furthermore, we found that transcription factor SOX4, a downstream target of TGFβ signaling, was activated in BC cells surviving from Verteporfin treatment. Manipulating SOX4 expression in BC cells changed Verteporfin sensitivity. Cells with enhanced SOX4 expression were more resistant to Verteporfin. These results elucidate a novel mechanism underlying Verteporfin resistance and suggest that Verteporfin and TGFβ inhibitors could work in combination to inhibit BC. In conclusion, we identified Verteporfin as a potential inhibitor of TAZ/YAP-driven signaling in BC, and established a global map of Verteporfin-response genes in BC cells. We systematically characterized the inhibitory effects of Verteporfin on BC cells at the molecular and cellular levels, and further identified SOX4-driven mechanism that mediates Verteporfin resistance. These results will facilitate the development of Verteporfin-based therapy for BC. Citation Format: Han Sun, Mingyao Ying. Small molecule drug Verteporfin inhibits TAZ/YAP-driven signaling and tumorigenicity of breast cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4444. doi:10.1158/1538-7445.AM2015-4444
Abstract Two-pore domain potassium (K2P) channels act to maintain cell resting membrane potential—a prerequisite for many biological processes. KCNK9, a member of K2P family, is implicated in cancer, owing to its overexpression in human tumours and its ability to promote neoplastic cell survival and growth. However, KCNK9’s underlying contributions to malignancy remain elusive due to the absence of specific modulators. Here we describe the development of monoclonal antibodies against the KCNK9 extracellular domain and their functional effects. We show that one antibody (Y4) with the highest affinity binding induces channel internalization. The addition of Y4 to KCNK9-expressing carcinoma cells reduces cell viability and increases cell death. Systemic administration of Y4 effectively inhibits growth of human lung cancer xenografts and murine breast cancer metastasis in mice. Evidence for Y4-mediated carcinoma cell autonomous and immune-dependent cytotoxicity is presented. Our study reveals that antibody-based KCNK9 targeting is a promising therapeutic strategy in KCNK9-expressing malignancies.
Despite evidence suggesting angina improvement after Coronary Sinus Reducer (CSR) implantation, the underlying mechanism remains to be confirmed. In a pilot study, we sought to assess changes in quantitative myocardial perfusion after CSR implantation in patients with refractory angina secondary to advanced coronary artery disease (CAD) using Rubidium-82 (Rb-82) Positron Emission Tomography (PET).
Methods
Data was collected prospectively for patients undergoing clinically indicated CSR implantation. Rb-82 PET was performed at rest and stress at baseline and median 6 months follow-up. QPET software was used for automatic segmentation into a 17 segment American Heart Association model and quantification of rest and stress myocardial blood flow (MBF, ml/min/g) and myocardial perfusion reserve (MPR).
Results
Five patients (3 male; 2 female) with mean age 69±16 years were recruited. Median Canadian Cardiovascular Society class was 3. Median number of anti-anginal medications was 3 and was unchanged during the follow-up period. 85 myocardial segments were analysed. Rest and stress MBF were corrected for rate-pressure product. Wilcoxon signed-rank tests were used to compare paired global and segmental perfusion values. A linear mixed-effects model with random slopes and intercepts was used to assess the relationship between baseline segmental MPR and associated change in MPR (delta MPR) after CSR implantation. Globally, there was no significant change in rest (P>0.99), stress MBF (P=0.63) or MPR (P=0.81) from baseline to follow-up. At a segmental level, there was no significant difference in MPR (P>0.57). However, the magnitude of change in MPR was related to the degree of baseline ischaemia (Figure 1). More ischaemic segments (baseline MPR<1.67) saw a greater increase in MPR after CSR whereas segments with higher baseline MPR values (MPR≥1.67) experienced a decrease (P=0.03, conditional R2 = 0.675). The median change in MPR in segments with a baseline MPR<1.67 (n=59) was 8.9% (delta MPR: +0.08; P=0.001) driven by a greater increase in stress MBF (15.6%, IQR: -2.1-42.2) compared to rest MBF (8.2%, IQR: -8.3-23.5; median of differences: 9.1%, P=0.0006) (Figure 2). In segments with baseline MPR≥1.67 (n=26) a 13.8% decrease in MPR was observed (delta MPR: -0.27; P=0.0003) driven by a greater decrease in stress MBF (-23.8%, IQR: -32.7-76.2) compared to rest MBF (-0.4%, IQR -24.33-72.9; median of differences: -11.5%, P= 0.0008). These changes in MPR remained significant when stratified by segments of the left (MPR<1.67: +0.08 [P=0.01]; MPR≥1.67: -0.20 [P=0.004]) and right (MPR<1.67: +0.11 [P=0.03]; MPR≥1.67: -0.27 [P=0.02]) coronary artery distributions.
Conclusions
To our knowledge, this is the first study showing changes in quantitative myocardial perfusion by PET after CSR implantation. Our segmental analysis demonstrates a relationship between baseline MPR and change in MPR after CSR implantation. In segments with MPR <1.67, the significant increase in MPR associated with CSR implantation was driven predominantly by greater increases in stress than rest MBF. By contrast, in segments with MPR≥1.67, follow-up MPR fell, driven by a reduction in stress MBF. Global values were unchanged. These quantitative preliminary data suggest redistribution of perfusion during stress as an effect of CSR implantation in patients with refractory angina secondary to advanced CAD. These pilot data require confirmation in adequately powered, double-blinded, randomised, sham-controlled studies.
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