Evelyn Sc Koay

Phosphorylation of Ser78 of Hsp27 correlated with HER-2/neu status and lymph node positivity in breast cancer

BackgroundAbnormal amplification/expression of HER-2/neu oncogene has been causally linked with tumorigenesis and metastasis in breast cancer and associated with shortened overall survival of patients. Recently, heat shock protein 27 (Hsp27) was reported to be highly expressed in HER-2/neu positive tumors and cell lines. However, putative functional links between phosphorylation of Hsp27 with HER-2/neu status and other clinicopathological features remain to be elucidated.ResultsComparative phosphoproteomic studies of HER-2/neu positive and -negative breast tumors revealed that Hsp27, one of the identified phosphoproteins, was highly phosphorylated in HER-2/neu positive tumors. The extent of Hsp27 phosphorylation at its Ser15, Ser78 and Ser82 residues were further evaluated with site-specific antibodies in tumor samples by tissue lysate array- and tissue microarray-based analyses, and in the BT474 breast cancer cell line treated with heregulin α1 (HRG α1) or the p38 MAPK inhibitor, SB203580. The tissue lysate array study indicated that only the level of pSer78 in HER-2/neu positive tumors was more than 2-fold that in HER-2/neu negative tumors. Treatment of BT474 cells with HRG α1 and SB203580 indicated that Ser78 phosphorylation was mainly regulated by the HER-2/neu-p38 MAPK pathway. Immunohistochemical staining of sections from a tissue microarray with 97 breast tumors showed that positive staining of pSer78 significantly correlated with HER-2/neu (p = 0.004) and lymph node positivity (p = 0.026).ConclusionThis investigation demonstrated the significant correlation of enhanced phosphorylation of the Ser78 residue of Hsp27 with HER-2/neu and lymph node positivity in breast cancer.

CYP2C19 and PON1 polymorphisms regulating clopidogrel bioactivation in Chinese, Malay and Indian subjects

UNLABELLED AIM, MATERIALS & METHODS: We investigated the functional significance of CYP2C19*2, *3, *17 and PON1 Q192R SNPs in 89 consecutive Asian patients on clopidogrel treatment and the prevalence of functionally significant polymorphisms among 300 Chinese, Malays and Asian Indians. RESULTS Both CYP2C19 loss-of-function alleles (*2 or *3) were associated with higher platelet reactivity while the CYP2C19 gain-of-function allele (*17) had lower platelet reactivity. For PON1, the median PRI was not significantly different between the QQ, QR and RR groups. The allele frequencies of CYP2C19*2, CYP2C19*3 and CYP2C19*17 were 0.280, 0.065 and 0.010 (rare) for Chinese, 0.310, 0.050 and 0.025 for Malays, and 0.375, 0.010 (rare) and 0.165 for Indians, respectively. CONCLUSION Our data suggest that genotyping studies to investigate clopidogrel response should include CYP2C19*2 and *3 but not *17 polymorphisms in Chinese, and CYP2C19*2 and *17 polymorphisms but not *3 in Indians. All three polymorphisms should preferably be genotyped in Malays.

Global epidemiology of non-influenza RNA respiratory viruses: data gaps and a growing need for surveillance

Summary Together with influenza, the non-influenza RNA respiratory viruses (NIRVs), which include respiratory syncytial virus, parainfluenza viruses, coronavirus, rhinovirus, and human metapneumovirus, represent a considerable global health burden, as recognised by WHOs Battle against Respiratory Viruses initiative. By contrast with influenza viruses, little is known about the contemporaneous global diversity of these viruses, and the relevance of such for development of pharmaceutical interventions. Although far less advanced than for influenza, antiviral drugs and vaccines are in different stages of development for several of these viruses, but no interventions have been licensed. This scarcity of global genetic data represents a substantial knowledge gap and impediment to the eventual licensing of new antiviral drugs and vaccines for NIRVs. Enhanced genetic surveillance will assist and boost research and development into new antiviral drugs and vaccines for these viruses. Additionally, understanding the global diversity of respiratory viruses is also part of emerging disease preparedness, because non-human coronaviruses and paramyxoviruses have been listed as priority concerns in a recent WHO research and development blueprint initiative for emerging infectious diseases. In this Personal View, we explain further the rationale for expanding the genetic database of NIRVs and emphasise the need for greater investment in this area of research.

Fructose transporters GLUT5 and GLUT2 expression in adult patients with fructose intolerance

Background Gastrointestinal symptoms and malabsorption following fructose ingestion (fructose intolerance) are common in functional gastrointestinal disorders (FGID). The underlying mechanism is unclear, but is hypothesized to be related an abnormality of intestinal fructose transporter proteins. Objective To assess the expression of the main intestinal fructose transporter proteins, glucose transport protein 5 (GLUT5) and 2 (GLUT2), in FGID. Methods The expression of GLUT5 and GLUT2 protein and mRNA in small intestinal biopsy tissue was investigated using real-time reverse-transcription PCR and Western immunoblotting in 11 adults with FGID and fructose intolerance ascertained by breath testing and in 15 controls. Results Median expression levels of GLUT5 mRNA normalized to beta-actin were 0.18 (interquartile range, IQR, 0.13–0.21) in patients and 0.17 (IQR 0.12–0.19) in controls (p > 0.05). Respective levels of GLUT2 mRNA were 0.26 (IQR 0.20–0.31) and 0.26 (IQR 0.19–0.31) (p > 0.05). Median expression levels of GLUT5 protein normalized to alpha-tubulin were 0.95 (IQR 0.52–1.68) in patients and 0.95 (IQR 0.59–1.15) in controls (p > 0.05). Respective protein expression levels for GLUT2 were 1.56 (IQR 1.06–2.14) and 1.35 (IQR 0.96–1.79) (p > 0.05). Conclusions Human fructose intolerance may not be associated with marked changes in GLUT5 and GLUT2 expression. Replication of these results in a larger subject group, including measures of transporter activation and membrane and subcellular localization, is warranted.

Sampling circulating tumor cells for clinical benefits: how frequent?

Circulating tumor cells (CTCs) are cells shed from tumors or metastatic sites and are a potential biomarker for cancer diagnosis, management, and prognostication. The majority of current studies use single or infrequent CTC sampling points. This strategy assumes that changes in CTC number, as well as phenotypic and molecular characteristics, are gradual with time. In reality, little is known today about the actual kinetics of CTC dissemination and phenotypic and molecular changes in the blood of cancer patients. Herein, we show, using clinical case studies and hypothetical simulation models, how sub-optimal CTC sampling may result in misleading observations with clinical consequences, by missing out on significant CTC spikes that occur in between sampling times. Initial studies using highly frequent CTC sampling are necessary to understand the dynamics of CTC dissemination and phenotypic and molecular changes in the blood of cancer patients. Such an improved understanding will enable an optimal, study-specific sampling frequency to be assigned to individual research studies and clinical trials and better inform practical clinical decisions on cancer management strategies for patient benefits.

Influenza outbreaks in Singapore: epidemiology, diagnosis, treatment and prevention

With the recent influenza A/H1N1 2009 pandemic still spreading through global populations, there has been an increased focus on optimizing the prevention, diagnosis and treatment of influenza infections, as well as the epidemiology of the virus. Clinical and epidemiological data on influenza infections in tropical countries have been relatively sparse until fairly recently, and it is the aim of this review to close some of these gaps by examining the behavior of influenza viruses in the tropical Singaporean population.

Tailoring of recommendations to reduce serious cutaneous adverse drug reactions: a pharmacogenomics approach

The Health Sciences Authority launched a pharmacogenetics initiative in 2008 to facilitate evaluation of pharmacogenetics associations pertinent for Chinese, Malays and Indians in Singapore. The aim was to reduce the incidence and unpredictability of serious adverse drug reactions, with a focus on serious skin adverse drug reactions. This paper describes the gathering of evidence and weighing of factors that led to different genotyping recommendations for HLA-B*15:02 with carbamazepine and HLA-B*58:01 with allopurinol, despite both having strong genetic associations. Translation of pharmacogenomics at a national level requires careful deliberation of the prevalence of at-risk allele, strength of genetic associations, positive predictive value, cost-effectiveness and availability of alternative therapies. Our experience provides a perspective on translating genomic discoveries in advancing drug safety.

Longitudinal monitoring reveals dynamic changes in circulating tumor cells (CTCs) and CTC-associated miRNAs in response to chemotherapy in metastatic colorectal cancer patients

We evaluated the changes in CTC count and CTC-associated miRNAs during the course of chemotherapy in patients with metastatic colorectal cancer. Blood samples were collected from 9 metastatic colorectal cancer patients prior to chemotherapy and at every other chemotherapy session during the course of treatment. CTCs were isolated and enumerated using a size-exclusion method (CellSievo, Singapore). CTC-associated miRNAs were isolated using a paper-based, partitioning method, and analyzed using reverse transcription quantitative real-time PCR (MiRXES, Singapore). CTC count trends generally correlated with disease progression defined by radiological measurements and trends in carcinoembryonic antigen (CEA) levels; hence CTC counts may be useful in cases where CEA is not elevated. CTC-associated miRNAs identified were miR-15b, miR-16, miR-19a, miR-21, miR-25, miR-30d, miR-126, miR-185, miR-221, miR-222, and miR-324-5p. The expression of CTC-associated miRNAs did not appear to correlate with CTC count and exhibited inter-individual heterogeneity. This pilot study suggests that analysis of CTC changes during the course of treatment may be useful in monitoring response to therapy in metastatic colorectal cancer.

Su2063 There Is No Relationship Between the Fructose Transporter, GLUT5 and GLUT2, Protein or mRNA Expression Levels in Irritable Bowel Syndrome With Fructose Malabsorption and Intolerance

Purpose: Poor sleep is commonly reported by patients with IBS. When stressed prior to bedtime patients with IBS show dysregulation of the pituitary-adrenal axis during sleep. Evidence suggests the tryptophan (TRP) metabolic pathways are also altered in patients with IBS. Our purpose was to determine whether alterations in TRP metabolism may be linked to cortisol in women with and without IBS. Methods: Women, ages 18-45, (n=46 IBS [Rome III]; controls [C; n=24]) were studied in a sleep laboratory and serum samples obtained on the third night following the introduction of a social stressor (anticipation of public speaking). Samples were obtained 2 hours following sleep onset (time 1) and 1 hour prior to awakening (time 2). All subjects completed a demographic data sheet, Rome III Diagnostic Questionnaire for Functional GI Disorders, Pittsburgh Quality Sleep Index (PSQI) and 28-day symptom diaries. Serum cortisol levels were determined by ELISA and metabolite levels by targeted liquid chromatography-mass spectrometry (LC-MS). Results: More women with IBS reported symptoms of insomnia (PSQI) as compared to C group (40% versus 24%) and reduced sleep efficiency by polysomnography (p<0.05). As reported previously cortisol/ACTH ratios were higher in IBS as compared to C women. Of the 6 kyneurinine pathway metabolites (primary TRP metabolic route) only niacinamide was significantly higher in women with IBS. However, 5-hydroxytryptophan levels were higher (p<.052) in women with IBS. None of the 3 methylation metabolites were significantly different between IBS and Cs. When ratios of metabolites were calculated significant differences were observed as shown in Table 1. Significant negative correlations between cortisol/ACTH and 5-hydroxytryptophan, methionine, kyneurinine, and betaine were found at one or both time points. TRP levels were significantly correlated with sleep quality (diary) in the IBS group. Conclusion: Nighttime levels of cortisol/ACTH are associated with metabolites in the TRP metabolic pathway particularly those associated with methylation. Whether these associations fully account for the frequent reports of poor sleep in women with IBS requires further study. Table 1