Glucose-induced phosphatidylinositol 3-kinase and mitogen-activated protein kinase-dependent upregulation of the platelet-derived growth factor-B receptor potentiates vascular smooth muscle cell chemotaxis

The aim of this study was to investigate the effects of elevated D-glucose concentrations on vascular smooth muscle cell (VSMC) expression of the platelet-derived growth factor (PDGF) beta receptor and VSMC migratory behavior. Immunoprecipitation, immunofluorescent staining, and RT-PCR of human VSMCs showed that elevated D-glucose induced an increase in the PDGF beta receptor that was inhibited by phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathway inhibitors. Exposure to 25 mmol/l D-glucose (HG) induced increased phosphorylation of protein kinase B (PKB) and extracellular-regulated kinase (ERK). All HG chemotaxis assays (with either 10 days' preincubation in HG or no preincubation) in a FCS or PDGF-BB gradient showed positive chemotaxis, whereas those in 5 mmol/l D-glucose did not. Assays were also run with concentrations ranging from 5 to 25 mmol/l D-glucose. Chemotaxis was induced at concentrations >9 mmol/l D-glucose. An anti-PDGF beta receptor antibody inhibited glucose-potentiated VSMC chemotaxis, as did the inhibitors for the PI3K and MAPK pathways. This study has shown that small increases in D-glucose concentration, for a short period, increase VSMC expression of the PDGF beta receptor and VSMC sensitivity to chemotactic factors in serum, leading to altered migratory behavior in vitro. It is probable that similar processes occur in vivo with glucose-enhanced chemotaxis of VSMCs, operating through PDGF beta receptor-operated pathways, contributing to the accelerated formation of atheroma in diabetes.

Polymorphims in the Interferon-y/Interleukin 26 Gene Region Contribute to Sex Bias in Susceptibility to Rheumatoid Arthritis

Objective:

To determine whether polymorphisms in the interferon-? (IFN?)/interleukin-26 (IL-26; formerly, AK155) gene cluster contribute to sex-based differential susceptibility to rheumatoid arthritis (RA).

Methods:

Four microsatellite markers, located in a 118-kb interval that contains both the IFN? and IL-26 genes on chromosome 12q15, were typed in 251 patients with RA and 198 unrelated healthy controls (all of whom lived in Northern Ireland) by means of polymerase chain reaction–based fragment analysis.

Results:

Marker D12S2510, which is located 3 kb 3' from the IL-26 gene, was significantly associated with RA in women (corrected P [Pcorr] = 0.008, 2 degrees of freedom [2 df]) but not in men (P = 0.99, 2 df). A 3-marker haplotype, IFNGCA*13;D12S2510*8;D12S2511*9, was inferred that showed significant underrepresentation in women with RA (odds ratio 0.50, 95% confidence interval 0.32–0.78; P = 0.002, Pcorr = 0.03) but not in men with RA.

Conclusion:

Our results demonstrate that common polymorphisms in the IFN?/IL-26 gene region may contribute to sex bias in susceptibility to RA, by distorting the propensity of female carriers versus male carriers to contract this disease. These results conform to our recent observations of a role for this gene cluster in sex-based differential susceptibility to another Th1-type inflammatory disease, multiple sclerosis.

Cathepsin S expression: An independent prognostic factor in glioblastoma tumours - A pilot Study

Cysteine proteinases have been implicated in astrocytoma invasion. We recently demonstrated that cathepsin S (CatS) expression is up-regulated in astrocytomas and provided evidence for a potential role in astrocytoma invasion (Flannery et al., Am J Path 2003;163(1):175–82). We aimed to evaluate the significance of CatS in human astrocytoma progression and as a prognostic marker. Frozen tissue homogenates from 71 patients with astrocytomas and 3 normal brain specimens were subjected to ELISA analyses. Immunohistochemical analysis of CatS expression was performed on 126 paraffin-embedded tumour samples. Fifty-one astrocytoma cases were suitable for both frozen tissue and paraffin tissue analysis. ELISA revealed minimal expression of CatS in normal brain homogenates. CatS expression was increased in grade IV tumours whereas astrocytoma grades I–III exhibited lower values. Immunohistochemical analysis revealed a similar pattern of expression. Moreover, high-CatS immunohistochemical scores in glioblastomas were associated with significantly shorter survival (10 vs. 5 months, p = 0.014). With forced inclusion of patient age, radiation dose and Karnofsky score in the Cox multivariate model, CatS score was found to be an independent predictor of survival. CatS expression in astrocytomas is associated with tumour progression and poor outcome in glioblastomas. CatS may serve as a useful prognostic indicator and potential target for anti-invasive therapy.

Differential Modulation of Transcriptional Activity of Estrogen Receptors by Direct Protein-Protein Interactions with the T Cell Factor Family of Transcription Factors

Two major signaling pathways, those triggered by estrogen (E(2)) and by the Wnt family, interact in the breast to cause growth and differentiation. The estrogen receptors ER(alpha) and ER(beta) are activated by binding E(2) and act as ligand-dependent transcription factors. The effector for the Wnt family is the Tcf family of transcription factors. Both sets of transcription factors recognize discrete but different nucleotide sequences in the promoters of their target genes. By using transient transfections of reporter constructs for the osteopontin and thymidine kinase promoters in rat mammary cells, we show that Tcf-4 antagonizes and Tcf-1 stimulates the effects of activated ER/E(2). For mutants of the former promoter, the stimulatory effects of ER(alpha)/E(2) can be made to be dependent on Tcf-1, and for the latter promoter the effects of the T cell factors (TCFs) are dependent on ER/E(2). Direct interaction between ERs and Tcfs either at the Tcf/ER(alpha)-binding site on the DNA or in the absence of DNA is established by gel retardation assays or by coimmunoprecipitation/biosensor methods, respectively. These results show that the two sets of transcription factors can interact directly, the interaction between ERs and Tcf-4 being antagonistic and that between ERs and Tcf-1 being synergistic on the activity of the promoters employed. Since Tcf-4 is the major Tcf family member in the breast, it is suggested that the antagonistic interaction is normally dominant in vivo in this tissue.