CXCL8 (also known as IL-8) activates CXCR1 and CXCR2 to mediate neutrophil recruitment and trigger cytotoxic effect at sites of infection. Under physiological conditions, CXCL8 could exist as monomers, dimers, or a mixture of monomers and dimers. Therefore, both forms of CXCL8 could interact with CXCR1 and CXCR2 with different affinities and potencies to mediate different cellular responses. In the present study, we have used a "trapped" nonassociating monomer (L25NMe) and a nondissociating dimer (R26C) to investigate their activities for human neutrophils that express both receptors and for RBL-2H3 cells stably expressing either CXCR1(RBL-CXCR1) or CXCR2 (RBL-CXCR2). The monomer was more active than the dimer for activities such as intracellular Ca(2+) mobilization, phosphoinositide hydrolysis, chemotaxis. and exocytosis. Receptor regulation, however, is distinct for each receptor. The rate of monomer-mediated regulation of CXCR1 is greater for activities such as phosphorylation, desensitization, beta-arrestin translocation, and internalization. In contrast, for CXCR2, both monomeric and dimeric CXCL8 mediate these activities to a similar extent. Interestingly, receptor-mediated signal-regulated kinase (ERK) phosphorylation in response to all three CXCL8 variants was more sustained for CXCR2 relative to CXCR1. Taken together, the results indicate that the CXCL8 monomer and dimer differentially activate and regulate CXCR1 and CXCR2 receptors. These distinct properties of the ligand and the receptors play a critical role in orchestrating neutrophil recruitment and eliciting cytotoxic activity during an inflammatory response.
Abstract Prostate cancer development and treatment has been associated with steroid hormones and/or steroid metabolites. While consensus seems to be building that serum testosterone levels are not related to disease risk, the role of genes involved in steroid metabolism have not been extensively studied. The UDP-glucuronosyltransferase (UGT) enzymes are part of a superfamily of genes involved in phase II detoxification of a wide variety of endogeneous and exogenous substances including bile, odorants, steroids, and drugs. The UGT2B17 gene is expressed in the prostate where it catalyzes the conjugation of a glucuronic acid moiety to steroids such as androstane-3α, 17βdiol. Several studies have examined whether a copy number variant (CNV) of UGT2B17 is associated with prostate cancer risk in case control studies, however, results have been inconclusive, and only one of the studies included African Americans. We examined the relationship of UGT2B17 CNV with prostate cancer risk aggressiveness in a hospital-based, case-control study conducted at the Durham Veterans Administration Hospital, and the relationship between serum levels of the glucuronide of androstane-3α, 17βdiol, AAG, in healthy Caucasians and African Americans. Levels of AAG were measured using ELISA. UGT2B17 genotype was determined by gene-specific copy number assays using Taqman Realtime PCR which showed 0, 1, or 2 alleles of the gene. Whereas CNV was not related to race (p=0.85), a higher CNV was significantly associated with higher androstane-3α, 17βdiol levels in healthy white men (p=0.018) but not non-white men (p=0.94). We found no association between CNV and cancer risk among all men (p=0.59) nor when stratified by white (p=0.70) vs. non-white (p=0.72). Among men with cancer, CNV was not related to Gleason score (p=0.32). These findings suggest that CNV may be associated with serum hormones levels, and these associations may differ between white and non-white men. Serum levels may be altered by other genetic or epigenetic factors in non-white populations. The role of CNV as a risk factor for prostate cancer requires further study in larger samples and with genetic and epigenetic variants. Funded by Department of Defense, NIH NCMHD P20 MD000175, S06-GM008049-33 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2770. doi:10.1158/1538-7445.AM2011-2770
Abstract An association between genetic variants in the vitamin D receptor ( VDR ) gene and epithelial ovarian cancer (EOC) was previously reported in women of African ancestry (AA). We sought to examine associations between genetic variants in VDR and additional genes from vitamin D biosynthesis and pathway targets ( EGFR, UGT1A, UGT2A1/2, UGT2B, CYP3A4/5 , CYP2R1 , CYP27B1 , CYP24A1 , CYP11A1 , and GC ). Genotyping was performed using the custom‐designed 533,631 SNP Illumina OncoArray with imputation to the 1,000 Genomes Phase 3 v5 reference set in 755 EOC cases, including 537 high‐grade serous (HGSOC), and 1,235 controls. All subjects are of African ancestry (AA). Logistic regression was performed to estimate odds ratios (OR) and 95% confidence intervals (CI). We further evaluated statistical significance of selected SNPs using the Bayesian False Discovery Probability (BFDP). A significant association with EOC was identified in the UGT2A1/2 region for the SNP rs10017134 (per allele OR = 1.4, 95% CI = 1.2‐1.7, P = 1.2 × 10 −6 , BFDP = 0.02); and an association with HGSOC was identified in the EGFR region for the SNP rs114972508 (per allele OR = 2.3, 95% CI = 1.6‐3.4, P = 1.6 × 10 −5 , BFDP = 0.29) and in the UGT2A1/2 region again for rs1017134 (per allele OR = 1.4, 95% CI = 1.2‐1.7, P = 2.3 × 10 −5 , BFDP = 0.23). Genetic variants in the EGFR and UGT2A1/2 may increase susceptibility of EOC in AA women. Future studies to validate these findings are warranted. Alterations in EGFR and UGT2A1/2 could perturb enzyme efficacy, proliferation in ovaries, impact and mark susceptibility to EOC.
Studies have suggested that abrogated expression of detoxification enzymes, UGT2B15 and UGT2B17, are associated with prostate tumour risk and progression. We investigated the role of EGF on the expression of these enzymes since it interacts with signalling pathways to also affect prostate tumour progression and is additionally associated with decreased DNA methylation. The expression of UGT2B15, UGT2B17, de novo methyltransferases, DNMT3A and DNMT3B was assessed in prostate cancer cells (LNCaP) treated with EGF, an EGFR inhibitor PD16893, and the methyltransferase inhibitor, 5-azacytidine, respectively. The results showed that EGF treatment decreased levels of expression of all four genes and that their expression was reversed by PD16893. Treatment with 5-azacytidine, markedly decreased expression of UGT2B15 and UGT2B17 over 85% as well as significantly decreased expression of DNMT3B, but not the expression of DNMT3A. DNMT3B siRNA treated LNCaP cells had decreased expression of UGT2B15 and UGT2B17, while DNMT3A siRNA treated cells had only moderately decreased UGT2B15 expression. Treatment with DNMT methyltransferase inhibitor, RG108, significantly decreased UGT2B17 expression. Additionally, methylation differences between prostate cancer samples and benign prostate samples from an Illumina 450K Methylation Array study were assessed. The results taken together suggest that hypomethylation of the UGT2B15 and UGT2B17 genes contributes to increased risk of prostate cancer and may provide a putative biomarker or epigenetic target for chemotherapeutics. Mechanistic studies are warranted to determine the role of the methylation marks in prostate cancer.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)