METHODS: We tested the ability of BA at neutral and acidic pH in inducing phosphatidylserine (PS) externalisation, reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP) disruption, and caspase 3/7 activity in normal nasopharyngeal epithelial (NP69) and NPC (TWO4) cells. Inverse-PCR (IPCR) was employed to detect AF9 gene cleavages. To investigate the role of CAD in mediating these cleavages, caspase inhibition was performed. IPCR bands representing AF9 cleaved fragments were sequenced.
RESULTS: BA-treated cells showed higher levels of PS externalisation, ROS production, MMP loss and caspase 3/7 activity than untreated control cells. The effect of BA in the induction of these intracellular events was enhanced by acid. BA at neutral and acidic pH also induced significant cleavage of the AF9 gene. These BA-induced gene cleavages were inhibited by Z-DEVD-FMK, a caspase-3 inhibitor. Intriguingly, a few chromosome breaks were identified within the AF9 region that was previously reported to participate in reciprocal translocation between the mixed lineage leukaemia (MLL) and AF9 genes in an acute lymphoblastic leukaemia (ALL) patient.
CONCLUSIONS: These findings suggest a role for BA-induced apoptosis in mediating chromosome rearrangements in NPC. In addition, CAD may be a key player in chromosome cleavages mediated by BA-induced apoptosis. Persistent exposure of sinonasal tract to gastric duodenal refluxate may increase genomic instability in surviving cells.
METHODS: 79 patients with DLBCL (nodal, 59% and extranodal, 41%) treated with rituximab combined with cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) therapy were selected. Expression levels of BCR and linked signalling pathway molecules were inter-related with Lymph2Cx-based cell of origin (COO) types and overall survival (OS).
RESULTS: Activated B-cell (ABC) type DLBCL constituted 49% (39/79) compared with germinal centre B-cell (GCB) type DLBCL (29/79; 37%) and revealed poor prognosis (p=0.013). In ABC-DLBCL, high BTK expression exerted poor response to R-CHOP, while OS in ABC-DLBCL with low BTK expression was similar to GCB-DLBCL subtype (p=0.004). High LYN expression coupled with a poor OS for ABC-DLBCL as well as GCB-DLBCL subtypes (p=0.001). Furthermore, high coexpression of BTK/LYN (BTKhigh/LYNhigh) showed poor OS (p=0.019), which linked with upregulation of several genes associated with BCR repertoire and nuclear factor-kappa B pathway (p<0.01). In multivariate analysis, high BTK and LYN expression retained prognostic significance against established clinical predictive factors such as age, International Prognostic Index and COO (p<0.05).
CONCLUSIONS: Our data provide a clear association between high BCR activity in DLBCL and response to therapy in a distinct population. Molecular data provided here will pave the pathway for the provision of promising novel-targeted therapies to patients with DLBCL in Southeast Asia.
OBJECTIVE: We examined whether adipocytokines might explain the ethnic differences in the relationship between obesity and insulin resistance among the three major ethnic groups in Singapore.
DESIGN AND PARTICIPANTS: This was a cross-sectional study of 101 Chinese, 82 Malays, and 81 South Asian men. Insulin sensitivity index (ISI) was measured using hyperinsulinemic euglycemic clamp. Visceral (VAT) and subcutaneous adipose tissue (SAT) volumes were quantified using magnetic resonance imaging.
MAIN OUTCOME MEASURES: Plasma total and high-molecular-weight adiponectin, leptin, visfatin, apelin, IL-6, fibroblast growth factor 21 (FGF21), retinol binding protein-4 (RBP 4), and resistin were measured using enzyme-linked immunoassays.
RESULTS: Principle component (PC) analysis on the adipocytokines identified three PCs, which explained 49.5% of the total variance. Adiponectin loaded negatively, and leptin and FGF21 loaded positively onto PC1. Visfatin, resistin, and apelin all loaded positively onto PC2. IL-6 loaded positively and RBP-4 negatively onto PC3. Only PC1 was negatively associated with ISI in all ethnic groups. In the path analysis, SAT and VAT were negatively associated with ISI in Chinese and Malays without significant mediatory role of PC1. In South Asians, the relationship between VAT and ISI was mediated partly through PC1, whereas the relationship between SAT and ISI was mediated mainly through PC1.
CONCLUSIONS: The relationships between abdominal obesity, adipocytokines and insulin sensitivity differ between ethnic groups. Adiponectin, leptin, and FGF21 play a mediating role in the relationship between abdominal adiposity and insulin resistance in South Asians, but not in Malays or Chinese.
BIOLOGICAL SIGNIFICANCE: In this study, proteomic analysis was used to identify abundant proteins from total protein extracts. PEG fractionation was used to reveal lower abundant proteins from both high and low proliferation embryogenic lines of oil palm samples in tissue culture. A total of 40 protein spots were found to be significant in abundance and the mRNA levels of 12 of these were assessed using real time PCR. Three proteins namely, triosephosphate isomerase, l-ascorbate peroxidase and superoxide dismutase were found to be concordant in their mRNA expression and protein abundance. Triosephosphate isomerase is a key enzyme in glycolysis. Both l-ascorbate peroxidase and superoxide dismutase play a role in anti-oxidative scavenging defense systems. These proteins have potential for use as biomarkers to screen for high and low embryogenic oil palm samples.