Ching Li

Distinct regulation of genes by bFGF and VEGF-A in endothelial cells

A finely tuned balance of angiogenic inhibitors and inducers controls the activity of angiogenesis characterized by proliferation, migration and differentiation of endothelial cells. Among many angiogenic factors, basic fibroblast growth factor (bFGF) was first identified to be angiogenic whereas vascular endothelial growth factor A (VEGF-A) is an endothelial cell specific mitogen. In addition to being a specific mitogen, VEGF-A is also known as a vascular permeability factor. The majority of growth factors transduce their mitogenic signals from cell surface to nucleus where gene expression occurs. Whether these ligands utilize a distinct or a common molecular pathway to exert their biological effects on human endothelial cells remains elusive. We thus studied the expression profile of 884 human genes under the influence of either bFGF or VEGF-A alone in the context of human endothelial cells. A total of ninety-four genes were differentially regulated by more than two folds. The expression patterns of 32 genes are similar between the treatment of either factor alone whereas those of the remaining 62 genes are only regulated by one but not the other factor. Their function in the control of angiogenesis will be discussed and apoptotic signaling in the regulation of angiogenesis is also implicated.

Microarray profiling of gene expression patterns in bladder tumor cells treated with genistein.

Microarray technology was used to gain an insight into the molecular events of tumor cell growth inhibition mediated by the soy isoflavone genistein. For this, a susceptible bladder tumor line TCCSUP was treated with the inhibitory dose (50 microM) of genistein for various periods of time, followed by mRNA isolations, cDNA probe preparations, and hybridization individually to cDNA chips containing 884 sequence-verified known human genes. After analyzing the hybridization signals with a simple quantitative method developed by this study, we detected that egr-1, whose expression has been associated with proliferation and differentiation, was transiently induced and this expression pattern was later confirmed by RT-PCR. Thus, microarray technology is a reliable and powerful tool for profiling gene expression patterns in many biological systems related to cancer. We further detected many groups of genes with distinct expression profiles and most of them encode for proteins that regulate the signal transduction or the cell cycle pathways. These genes warrant further investigation as regards their roles in the susceptibility of the tumor cell line to the antitumor drug.

Anti-angiogenesis mediated by angiostatin K1-3, K1-4 and K1-4.5. Involvement of p53, FasL, AKT and mRNA deregulation

The molecular mechanism mediated by multiple forms of angiostatin via acting on proliferating vascular endothelium remains elusive. To address whether three forms of angiostatin, K1-3, K1-4 or K1-4.5, utilized similar or distinct pathways to mediate anti-angiogenesis, we adopted an adenoviral expression system to express secretable angiostatin molecules for CM collection. The anti-angiogenic activity of K1-3, K1-4 or K1-4.5 was confirmed by using proliferation, migration, tube formation and apoptotic assays of human endothelial cells. These angiostatin molecules at comparable expression level inhibited various in vitro angiogenesis assays with some variations. Furthermore, K1-3, K1-4 or K1-4.5 increased the expression of p53 protein and its downstream effectors, enhanced FasL-mediated signaling pathways, and decreased activation of AKT. At least three different receptors, Fas, integrin alpha(v)beta3 and ATP synthase, were involved in the anti-angiogenic action of angiostatin molecules. Besides, the expression of 189 genes at mRNA level was significantly altered by K1-3, K1-4 or K1-4.5. More than 70% of these genes participate in growth, inflammation, apoptosis, migration and extracellular matrix. Taken together, K1-3, K1-4 and K1-4.5, regardless of the number of kringles in the angiostatin molecules, mediated anti-angiogenesis via mostly similar pathways. We are the first to demonstrate the involvement of DAPK1 in the mediation of anti-angiogenesis by angiostatin.

CC chemokines induce neutrophils to chemotaxis, degranulation, and alpha-defensin release

We have previously shown that a Taiwanese cohort of HIV-uninfected individuals was associated with the significantly elevated levels of serum β-chemokines, macrophage inflammatory protein (MIP-1)-α and MIP-β, and RANTES. In the present study, we report that the members of this cohort have significantly greater numbers of lower buoyant-density neutrophils in their blood, which leads to further investigation of the effects of β-chemokines on neutrophils. By electron and confocal microscopic techniques and FACScan, the results demonstrated that MIP-1α, MIP-β, and/or RANTES readily activated the cells to release a large quantity of α-defensins in vitro through the degranulation process, which was the cause of low-buoyant-density neutrophil production. The purified neutrophils underwent chemotaxis and increased phagocytic capability when β-chemokines were present. Only when using all 3 neutralizing antibodies for CCR1, CCR3, and CCR5 could the chemotaxis of neutrophils be inhibited completely, suggesting that these receptors are involved in transducing activating signals. Because neutrophils are the most abundant white blood cells that can be activated simultaneously to release α-defensins and because these proteins are antiviral, including anti-HIV, our results support the hypothesis that in addition to β-chemokines, the innate immunity of the cohort plays a role in inhibiting the transmission of HIV.

Environmental factors, parental atopy and atopic eczema in primary‐school children: a cross‐sectional study in Taiwan

Background  Parental atopy and environmental exposure are recognized risk factors for atopic eczema (AE) in childhood. However, the relative contributions of specific risk factors and the overall contributions of hereditary and environmental exposure remain unexplored.

Increasing prevalence of atopic eczema in Taiwanese adolescents from 1995 to 2001.

Background The prevalence of atopic eczema in adolescents has recently been reported as increasing in many countries, a phenomenon yet to be fully explained. This study compared the prevalence of atopic eczema among Taiwanese adolescents with individual‐level risk factors and community‐level data of temperature, relative humidity, and air pollutants to determine whether changes in these factors could explain the observed change in prevalence.