👤 Guan Poh Tay

Atherosclerosis preferentially develops in regions exposed to disturbed flow, where is more susceptible to trans-endothelial retention of oxidized low-density lipoprotein (ox-LDL) and subsequent vascular inflammation. While 12/15-lipoxygenase (12/15-LOX) is implicated in lipid oxidation, its role in accumulation of oxLDL in disturbed flow areas remains unknown. Human coronary artery endarterectomy specimens and cultured endothelial cells were analyzed for 12/15-LOX expression and localization under disturbed flow. Oxidized phospholipids were quantified via E06 antibody by ELISA, while ROS generation was measured using DCFH-DA. ApoE Disturbed flow upregulated 12/15-LOX expression in endothelial cells. In vitro, disturbed flow increased LDL oxidation and ROS production, both attenuated by 12/15-LOX siRNA or the specific inhibitor baicalein and ML351. Genetic deletion or pharmacological inhibition of 12/15-LOX reduced oxidized lipid deposition in disturbed flow regions. Mechanistically, 12/15-LOX increased ROS production in disturbed flow conditions in a pathway upstream of NAPDH oxidase 2. However, the 12/15-LOX-mediated LDL oxidation was independent of NOX. We identify 12/15-LOX as a hemodynamic-sensitive enzyme that is upregulated under disturbed flow to promote LDL oxidation, which proposes a promising target to mitigate atherosclerosis especially in disturbed flow areas. Show less

Epithelial-to-mesenchymal transition (EMT) plays a crucial role in metastatic cancer progression, and current research, which relies heavily on 2D monolayer cultures, falls short in recapitulating the complexity of a 3D tumor microenvironment. To address this limitation, a transcriptomic meta-analysis is conducted on diverse cancer types undergoing EMT in 2D and 3D cultures. It is found that mechanotransduction is elevated in 3D cultures and is further intensified during EMT, but not during 2D EMT. This analysis reveals a distinct 3D EMT gene signature, characterized by extracellular matrix remodeling coordinated by angiopoietin-like 4 (Angptl4) along with other canonical EMT regulators. Utilizing hydrogel-based 3D matrices with adjustable mechanical forces, 3D cancer cultures are established at varying physiological stiffness levels. A YAP:EGR-1 mediated up-regulation of Angptl4 expression is observed, accompanied by an upregulation of mesenchymal markers, at higher stiffness during cancer EMT. Suppression of Angptl4 using antisense oligonucleotides or anti-cAngptl4 antibodies leads to a dose-dependent abolishment of EMT-mediated chemoresistance and tumor self-organization in 3D, ultimately resulting in diminished metastatic potential and stunted growth of tumor xenografts. This unique programmable 3D cancer cultures simulate stiffness levels in the tumor microenvironment and unveil Angptl4 as a promising therapeutic target to inhibit EMT and impede cancer progression. Show less

The senescence-associated secretory phenotype (SASP) can promote paracrine invasion while suppressing tumour growth, thus generating complex phenotypic outcomes. Likewise, centrosome amplification can induce proliferation arrest yet also facilitate tumour invasion. However, the eventual fate of cells with centrosome amplification remains elusive. Here, we report that centrosome amplification induces a variant of SASP, which constitutes a pathway activating paracrine invasion. The centrosome amplification-induced SASP is non-canonical as it lacks the archetypal detectable DNA damage and prominent NF-κB activation, but involves Rac activation and production of reactive oxygen species. Consequently, it induces hypoxia-inducible factor 1α and associated genes, including pro-migratory factors such as ANGPTL4. Of note, cellular senescence can either induce tumourigenesis through paracrine signalling or conversely suppress tumourigenesis through p53 induction. By analogy, centrosome amplification-induced SASP may therefore be one reason why extra centrosomes promote malignancy in some experimental models but are neutral in others. Show less

Our objective was to examine differences in cytokine/chemokine response in chronic hepatitis B(CHB) patients to understand the immune mechanism of HBsAg loss (functional cure) during antiviral therapy. We used an unbiased machine learning strategy to unravel the immune pathways in CHB nucleo(t)side analogue-treated patients who achieved HBsAg loss with peg-interferon-α(peg-IFN-α) add-on or switch treatment in a randomised clinical trial. Cytokines/chemokines from plasma were compared between those with/without HBsAg loss, at baseline, before and after HBsAg loss. Peg-IFN-α treatment resulted in higher levels of IL-27, IL-12p70, IL-18, IL-13, IL-4, IL-22 and GM-CSF prior to HBsAg loss. Probabilistic network analysis of cytokines, chemokines and soluble factors suggested a dynamic dendritic cell driven NK and T cell immune response associated with HBsAg loss. Bayesian network analysis showed a dominant myeloid-driven type 1 inflammatory response with a MIG and I-TAC central module contributing to HBsAg loss in the add-on arm. In the switch arm, HBsAg loss was associated with a T cell activation module exemplified by high levels of CD40L suggesting T cell activation. Our findings show that more than one immune pathway to HBsAg loss was found with peg-IFN-α therapy; by myeloid-driven Type 1 response in one instance, and T cell activation in the other. Show less

Extracellular vesicles (EVs) mediate critical intercellular communication within healthy tissues, but are also exploited by tumour cells to promote angiogenesis, metastasis, and host immunosuppression under hypoxic stress. We hypothesize that hypoxic tumours synthesize hypoxia-sensitive proteins for packing into EVs to modulate their microenvironment for cancer progression. In the current report, we employed a heavy isotope pulse/trace quantitative proteomic approach to study hypoxia sensitive proteins in tumour-derived EVs protein. The results revealed that hypoxia stimulated cells to synthesize EVs proteins involved in enhancing tumour cell proliferation (NRSN2, WISP2, SPRX1, LCK), metastasis (GOLM1, STC1, MGAT5B), stemness (STC1, TMEM59), angiogenesis (ANGPTL4), and suppressing host immunity (CD70). In addition, functional clustering analyses revealed that tumour hypoxia was strongly associated with rapid synthesis and EV loading of lysosome-related hydrolases and membrane-trafficking proteins to enhance EVs secretion. Moreover, lung cancer-derived EVs were also enriched in signalling molecules capable of inducing epithelial-mesenchymal transition in recipient cancer cells to promote their migration and invasion. Together, these data indicate that lung-cancer-derived EVs can act as paracrine/autocrine mediators of tumorigenesis and metastasis in hypoxic microenvironments. Tumour EVs may, therefore, offer novel opportunities for useful biomarkers discovery and therapeutic targeting of different cancer types and at different stages according to microenvironmental conditions. Show less

The United Arab Emirates (UAE) is one of the countries most threatened with obesity. Here we investigated associations between hundreds of single-nucleotide polymorphisms (SNPs) and the following obesity indicators: body mass index (BMI), waist circumference (WC), and height. We also investigated the associations between obesity-related genes with type 2 diabetes mellitus (T2DM). We tested 87, 58, and 586 SNPs in a previous genome-wide significance level for associations with BMI (n = 880), WC (n = 455), and height (n = 897), respectively. For each trait, we used normally transformed Z scores and tested them with SNPs using linear regression models that incorporated age and gender as covariates. The weighted polygenic risk scores for significant SNPs for each trait were tested with the corresponding Z scores using linear regression models with the same covariates. We further tested 145 obesity loci with T2DM (464 cases, 415 controls) using a logistic regression model including age, gender, and BMI Z scores as covariates. The Mean BMI was 29.39 kg/m In this first study of Arab descendants, we confirmed several known obesity (FTO, USP37, and RFX7), height (NSD1, MFAP2), and T2DM (TCF7L2, MC4R) associations; and report novel associations, like KCNK3 and RARB for T2DM. Show less