MyMedR

Proteomic Characterization and Comparison of Malaysian Tropidolaemus wagleri and Cryptelytrops purpureomaculatus Venom Using Shotgun-Proteomics

Zainal Abidin SA, Rajadurai P, Chowdhury ME, Ahmad Rusmili MR, Othman I, Naidu R

Toxins (Basel), 2016 10 18;8(10).

PMID: 27763534

Tropidolaemus wagleri and Cryptelytrops purpureomaculatus are venomous pit viper species commonly found in Malaysia. Tandem mass spectrometry analysis of the crude venoms has detected different proteins in T. wagleri and C. purpureomaculatus. They were classified into 13 venom protein families consisting of enzymatic and nonenzymatic proteins. Enzymatic families detected in T. wagleri and C. purpureomaculatus venom were snake venom metalloproteinase, phospholipase A₂, ʟ-amino acid oxidase, serine proteases, 5'-nucleotidase, phosphodiesterase, and phospholipase B. In addition, glutaminyl cyclotransferase was detected in C. purpureomaculatus. C-type lectin-like proteins were common nonenzymatic components in both species. Waglerin was present and unique to T. wagleri-it was not in C. purpureomaculatus venom. In contrast, cysteine-rich secretory protein, bradykinin-potentiating peptide, and C-type natriuretic peptide were present in C. purpureomaculatus venom. Composition of the venom proteome of T. wagleri and C. purpureomaculatus provides useful information to guide production of effective antivenom and identification of proteins with potential therapeutic applications.

Fulltext Aids to diagnosis of nasopharyngeal carcinoma

Umapati P, Rajadurai P, Kook SC, Lekhraj R, Singh J

Med J Malaysia, 1988 Jun;43(2):109-16.

PMID: 3237126

Occult primary breast carcinoma presented as an axillary mass: A Diagnostic Challenge

Wong YP, Tan GC, Muhammad R, Rajadurai P

Malays J Pathol, 2020 Apr;42(1):151-155.

PMID: 32342946

INTRODUCTION: Occult primary breast carcinoma (OBC) manifesting as axillary nodal metastasis without an identifiable breast primary is exceptionally rare. It continues to pose a diagnostic challenge to pathologists. Here, we report a case of OBC with emphasis on the usefulness of immunohistochemistry to determine the primary site of tumour.

CASE REPORT: A 58-year-old female presented with a 3-cm painless right axillary mass. Extensive radiological investigations that include mammography, ultrasonography of the breasts and positron emission tomography (PET) scan failed to conclude the primary site of the tumour. Histological examination of the lymph node revealed loosely cohesive sheets of poorly differentiated malignant cells, without discernible glandular or squamous differentiation. Immunohistochemically, the malignant cells exhibited diffuse immunoreactivity toward pan-cytokeratin and CK7, while leukocyte common antigen, S100 and CK20 were negative. A second panel of immunomarkers was carried out. The malignant cells expressed breast-specific markers (GATA-3, GCDFP-15 and mammaglobin), and were negative for ER, PR and TTF-1 immunohistochemistry. A diagnosis of OBC was rendered.

DISCUSSION: Breast primary must always be considered in the differential diagnosis in patients with sole presentation of axillary lymphadenopathy. The breast-specific immunomarkers play a pivotal role in the diagnosis of ER, PR-negative occult breast cancer.

Down-regulation of LPA receptor 5 contributes to aberrant LPA signalling in EBV-associated nasopharyngeal carcinoma

Yap LF, Velapasamy S, Lee HM, Thavaraj S, Rajadurai P, Wei W, et al.

J Pathol, 2015 Feb;235(3):456-65.

PMID: 25294670 DOI: 10.1002/path.4460

Undifferentiated nasopharyngeal carcinoma (NPC) is a highly metastatic disease that is consistently associated with Epstein-Barr virus (EBV) infection. In this study, we have investigated the contribution of lysophosphatidic acid (LPA) signalling to the pathogenesis of NPC. Here we demonstrate two distinct functional roles for LPA in NPC. First, we show that LPA enhances the migration of NPC cells and second, that it can inhibit the activity of EBV-specific cytotoxic T cells. Focusing on the first of these phenotypes, we show that one of the LPA receptors, LPA receptor 5 (LPAR5), is down-regulated in primary NPC tissues and that this down-regulation promotes the LPA-induced migration of NPC cell lines. Furthermore, we found that EBV infection or ectopic expression of the EBV-encoded LMP2A was sufficient to down-regulate LPAR5 in NPC cell lines. Our data point to a central role for EBV in mediating the oncogenic effects of LPA in NPC and identify LPA signalling as a potential therapeutic target in this disease.

Thyroid metastasis from nasopharyngeal carcinoma: a case report

Jalaludin MA, Rajadurai P, Va R, Prasad U

J Laryngol Otol, 1994 Oct;108(10):886-8.

PMID: 7989842 DOI: 10.1017/s0022215100128415

Anaplastic nasopharyngeal carcinoma (NPC) metastatic to the thyroid gland is rare. We report the first such case in a 54-year-old Malaysian Chinese woman. The correct diagnosis should be made so that thyroidectomy may be avoided and an appropriate chemoradiotherapeutic regimen instituted.

Fulltext Monoamine oxidase A is down-regulated in EBV-associated nasopharyngeal carcinoma

Lee HM, Sia APE, Li L, Sathasivam HP, Chan MSA, Rajadurai P, et al.

Sci Rep, 2020 04 09;10(1):6115.

PMID: 32273550 DOI: 10.1038/s41598-020-63150-0

Nasopharyngeal carcinoma (NPC) is a highly metastatic cancer that is consistently associated with Epstein-Barr virus (EBV) infection. In this study, we identify for the first time a role for monoamine oxidase A (MAOA) in NPC. MAOA is a mitochondrial enzyme that catalyzes oxidative deamination of neurotransmitters and dietary amines. Depending on the cancer type, MAOA can either have a tumour-promoting or tumour-suppressive role. We show that MAOA is down-regulated in primary NPC tissues and its down-regulation enhances the migration of NPC cells. In addition, we found that EBV infection can down-regulate MAOA expression in both pre-malignant and malignant nasopharyngeal epithelial (NPE) cells. We further demonstrate that MAOA is down-regulated as a result of IL-6/IL-6R/STAT3 signalling and epigenetic mechanisms, effects that might be attributed to EBV infection in NPE cells. Taken together, our data point to a central role for EBV in mediating the tumour suppressive effects of MAOA and that loss of MAOA could be an important step in the pathogenesis of NPC.

Fulltext HOPX functions as a tumour suppressor in head and neck cancer

Yap LF, Lai SL, Patmanathan SN, Gokulan R, Robinson CM, White JB, et al.

Sci Rep, 2016 Dec 09;6:38758.

PMID: 27934959 DOI: 10.1038/srep38758

Head and neck squamous cell carcinoma (HNSCC) is generalized term that encompasses a diverse group of cancers that includes tumours of the oral cavity (OSCC), oropharynx (OPSCC) and nasopharynx (NPC). Genetic alterations that are common to all HNSCC types are likely to be important for squamous carcinogenesis. In this study, we have investigated the role of the homeodomain-only homeobox gene, HOPX, in the pathogenesis of HNSCC. We show that HOPX mRNA levels are reduced in OSCC and NPC cell lines and tissues and there is a general reduction of HOPX protein expression in these tumours and OPSCCs. HOPX promoter methylation was observed in a subset of HNSCCs and was associated with a worse overall survival in HPV negative tumours. RNAseq analysis of OSCC cells transfected with HOPX revealed a widespread deregulation of the transcription of genes related to epithelial homeostasis and ectopic over-expression of HOPX in OSCC and NPC cells inhibited cell proliferation, plating efficiency and migration, and enhanced sensitivity to UVA-induced apoptosis. Our results demonstrate that HOPX functions as a tumour suppressor in HNSCC and suggest a central role for HOPX in suppressing epithelial carcinogenesis.

Fulltext Mantle cell lymphoma of palatine tonsil: A case report

Pailoor J, Ramasamy V, Bahnu YS, Koay CE, Chang KM, Rajadurai P

Respir Med Case Rep, 2020;31:101218.

PMID: 32995259 DOI: 10.1016/j.rmcr.2020.101218

Fulltext A case-control study of breast cancer risk factors in 7,663 women in Malaysia

Tan MM, Ho WK, Yoon SY, Mariapun S, Hasan SN, Lee DS, et al.

PLoS One, 2018;13(9):e0203469.

PMID: 30216346 DOI: 10.1371/journal.pone.0203469

BACKGROUND: Breast cancer risk factors have been examined extensively in Western setting and more developed Asian cities/countries. However, there are limited data on developing Asian countries. The purpose of this study was to examine breast cancer risk factors and the change of selected risk factors across birth cohorts in Malaysian women.

METHODS: An unmatched hospital based case-control study was conducted from October 2002 to December 2016 in Selangor, Malaysia. A total of 3,683 cases and 3,980 controls were included in this study. Unconditional logistic regressions, adjusted for potential confounding factors, were conducted. The breast cancer risk factors were compared across four birth cohorts by ethnicity.

RESULTS: Ever breastfed, longer breastfeeding duration, a higher soymilk and soy product intake, and a higher level of physical activity were associated with lower risk of breast cancer. Chinese had the lowest breastfeeding rate, shortest breastfeeding duration, lowest parity and highest age of first full term pregnancy.

CONCLUSIONS: Our study shows that breastfeeding, soy intake and physical activity are modifiable risk factors for breast cancer. With the increasing incidence of breast cancer there is an urgent need to educate the women about lifestyle intervention they can take to reduce their breast cancer risk.

Fulltext The molecular landscape of Asian breast cancers reveals clinically relevant population-specific differences

Pan JW, Zabidi MMA, Ng PS, Meng MY, Hasan SN, Sandey B, et al.

Nat Commun, 2020 Dec 22;11(1):6433.

PMID: 33353943 DOI: 10.1038/s41467-020-20173-5

Molecular profiling of breast cancer has enabled the development of more robust molecular prognostic signatures and therapeutic options for breast cancer patients. However, non-Caucasian populations remain understudied. Here, we present the mutational, transcriptional, and copy number profiles of 560 Malaysian breast tumours and a comparative analysis of breast cancers arising in Asian and Caucasian women. Compared to breast tumours in Caucasian women, we show an increased prevalence of HER2-enriched molecular subtypes and higher prevalence of TP53 somatic mutations in ER+ Asian breast tumours. We also observe elevated immune scores in Asian breast tumours, suggesting potential clinical response to immune checkpoint inhibitors. Whilst HER2-subtype and enriched immune score are associated with improved survival, presence of TP53 somatic mutations is associated with poorer survival in ER+ tumours. Taken together, these population differences unveil opportunities to improve the understanding of this disease and lay the foundation for precision medicine in different populations.

Fulltext Erratum: Publisher Correction: Homologous recombination DNA repair defects in PALB2-associated breast cancers

Li A, Geyer FC, Blecua P, Lee JY, Selenica P, Brown DN, et al.

NPJ Breast Cancer, 2019 11 19;5:44.

PMID: 31754629 DOI: 10.1038/s41523-019-0140-8

[This corrects the article DOI: 10.1038/s41523-019-0115-9.].

Fulltext Characterisation of PALB2 tumours through whole-exome and whole-transcriptomic analyses

Ng PS, Pan JW, Ahmad Zabidi MM, Rajadurai P, Yip CH, Reuda OM, et al.

NPJ Breast Cancer, 2021 Apr 23;7(1):46.

PMID: 33893315 DOI: 10.1038/s41523-021-00254-4

Rare protein-truncating variants (PTVs) in PALB2 confer increased risk to breast cancer, but relatively few studies have reported the characteristics of tumours with PALB2 PTVs. In this study, we describe molecular characteristics of tumours with either germline or somatic alterations in PALB2. DNA from fresh frozen tumour tissues and matched peripheral blood lymphocytes for 560 breast cancer patients was subjected for whole-exome sequencing (WES), and RNA from tumour tissues was subjected to RNA sequencing (RNA-seq). We found six cases with germline and three with somatic protein-truncating variants in PALB2. The characteristics of tumours in patients with PALB2 PTVs were similar to those with BRCA1 and BRCA2 PTVs, having significantly more somatic alterations, and a high proportion of the mutational signature and genomic scar scores characteristic of deficiencies in homologous recombination (HR), compared to tumours arising in non-carriers. Unlike tumours arising in patients with BRCA1 and BRCA2 PTVs, PALB2 tumours did not have high prevalence of TP53 somatic alterations or an enriched immune microenvironment. In summary, PALB2 tumours show the homologous recombination deficiencies characteristic of BRCA1 and BRCA2 tumours, and highlight the potential clinical relevance of PALB2 mutational status in guiding therapeutic choices.

Fulltext Homologous recombination DNA repair defects in PALB2-associated breast cancers

Li A, Geyer FC, Blecua P, Lee JY, Selenica P, Brown DN, et al.

NPJ Breast Cancer, 2019;5:23.

PMID: 31428676 DOI: 10.1038/s41523-019-0115-9

Mono-allelic germline pathogenic variants in the Partner And Localizer of BRCA2 (PALB2) gene predispose to a high-risk of breast cancer development, consistent with the role of PALB2 in homologous recombination (HR) DNA repair. Here, we sought to define the repertoire of somatic genetic alterations in PALB2-associated breast cancers (BCs), and whether PALB2-associated BCs display bi-allelic inactivation of PALB2 and/or genomic features of HR-deficiency (HRD). Twenty-four breast cancer patients with pathogenic PALB2 germline mutations were analyzed by whole-exome sequencing (WES, n = 16) or targeted capture massively parallel sequencing (410 cancer genes, n = 8). Somatic genetic alterations, loss of heterozygosity (LOH) of the PALB2 wild-type allele, large-scale state transitions (LSTs) and mutational signatures were defined. PALB2-associated BCs were found to be heterogeneous at the genetic level, with PIK3CA (29%), PALB2 (21%), TP53 (21%), and NOTCH3 (17%) being the genes most frequently affected by somatic mutations. Bi-allelic PALB2 inactivation was found in 16 of the 24 cases (67%), either through LOH (n = 11) or second somatic mutations (n = 5) of the wild-type allele. High LST scores were found in all 12 PALB2-associated BCs with bi-allelic PALB2 inactivation sequenced by WES, of which eight displayed the HRD-related mutational signature 3. In addition, bi-allelic inactivation of PALB2 was significantly associated with high LST scores. Our findings suggest that the identification of bi-allelic PALB2 inactivation in PALB2-associated BCs is required for the personalization of HR-directed therapies, such as platinum salts and/or PARP inhibitors, as the vast majority of PALB2-associated BCs without PALB2 bi-allelic inactivation lack genomic features of HRD.

Fulltext Cytotoxic, Anti-Proliferative and Apoptosis Activity of l-Amino Acid Oxidase from Malaysian Cryptelytrops purpureomaculatus (CP-LAAO) Venom on Human Colon Cancer Cells

Zainal Abidin SA, Rajadurai P, Hoque Chowdhury ME, Othman I, Naidu R

Molecules, 2018 06 08;23(6).

PMID: 29890640 DOI: 10.3390/molecules23061388

The aim of this study is to investigate the potential anti-cancer activity of l-amino acid oxidase (CP-LAAO) purified from the venom of Cryptelytrops purpureomaculatus on SW480 and SW620 human colon cancer cells. Mass spectrometry guided purification was able to identify and purify CP-LAAO. Amino acid variations identified from the partial protein sequence of CP-LAAO may suggest novel variants of these proteins. The activity of the purified CP-LAAO was confirmed with o-phenyldiamine (OPD)-based spectrophotometric assay. CP-LAAO demonstrated time- and dose-dependent cytotoxic activity and the EC50 value was determined at 13 µg/mL for both SW480 and SW620 cells. Significant increase of caspase-3 activity, reduction of Bcl-2 levels, as well as morphological changes consistent with apoptosis were demonstrated by CP-LAAO. Overall, these data provide evidence on the potential anti-cancer activity of CP-LAAO from the venom of Malaysian C. purpureomaculatus for therapeutic intervention of human colon cancer.

Fulltext Molecular testing for advanced non-small cell lung cancer in Malaysia: Consensus statement from the College of Pathologists, Academy of Medicine Malaysia, the Malaysian Thoracic Society, and the Malaysian Oncological Society

Rajadurai P, Cheah PL, How SH, Liam CK, Annuar MAA, Omar N, et al.

Lung Cancer, 2019 10;136:65-73.

PMID: 31446227 DOI: 10.1016/j.lungcan.2019.08.005

In the recent years, increased understanding of the molecular profiles of non-small cell lung cancer (NSCLC) has allowed for targeted treatment of actionable genetic mutations. The management of NSCLC now requires multiple molecular tests to guide the treatment strategy. In the light of this, there is a need to establish a molecular testing consensus statement for advanced NSCLC patients in Malaysia. This Malaysian consensus statement was developed by a panel of experts, chaired by a pathologist and composed of three other pathologists, four respiratory physicians and three oncologists. It reflects currently available scientific data and adaptations of recommendations from international guidelines to the local landscape. Expert recommendations on different aspects of molecular testing agreed upon by the panel are provided as structured discussions. These recommendations address the appropriate patients and samples to be tested, as well as when and how these tests should be performed. The algorithms for molecular testing in metastatic NSCLC, in the first line setting and upon disease progression beyond first line therapy, were developed.

Fulltext EGFR mutation testing practices within the Asia Pacific region: results of a multicenter diagnostic survey

Yatabe Y, Kerr KM, Utomo A, Rajadurai P, Tran VK, Du X, et al.

J Thorac Oncol, 2015 Mar;10(3):438-45.

PMID: 25376513 DOI: 10.1097/JTO.0000000000000422

The efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in EGFR mutation-positive non-small-cell lung cancer (NSCLC) patients necessitates accurate, timely testing. Although EGFR mutation testing has been adopted by many laboratories in Asia, data are lacking on the proportion of NSCLC patients tested in each country, and the most commonly used testing methods.

Fulltext Epidermal growth factor receptor mutations in lung adenocarcinoma in Malaysian patients

Liam CK, Wahid MI, Rajadurai P, Cheah YK, Ng TS

J Thorac Oncol, 2013 Jun;8(6):766-72.

PMID: 23575413 DOI: 10.1097/JTO.0b013e31828b5228

Despite available data from other Asian countries, the prevalence of epidermal growth factor receptor (EGFR) mutations among lung adenocarcinoma patients has not been reported in Malaysia. This study sought to determine the frequency of EGFR mutations among multiethnic Malaysian patients diagnosed with lung adenocarcinoma.

Lung Cancer in Malaysia

Rajadurai P, How SH, Liam CK, Sachithanandan A, Soon SY, Tho LM

J Thorac Oncol, 2020 03;15(3):317-323.

PMID: 32093853 DOI: 10.1016/j.jtho.2019.10.021

Fulltext Epithelial-to-mesenchymal transition (EMT) causing acquired resistance to afatinib in a patient with epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma

Poh ME, Liam CK, Rajadurai P, Chai CS

J Thorac Dis, 2018 Jul;10(7):E560-E563.

PMID: 30174934 DOI: 10.21037/jtd.2018.06.122

We report the first case of epithelial-to-mesenchymal transition (EMT) as the cause of acquired resistance to the second-generation EGFR-tyrosine kinase inhibitor (TKI), afatinib in a patient with advanced non-small cell lung cancer (NSCLC) harboring a sensitizing EGFR mutation. Patients with EGFR-mutant NSCLC inevitably develop acquired resistance while on EGFR-TKI treatment. EMT which renders cancer cells more invasive and migratory is one of the mechanisms of acquired resistance to EGFR-TKIs and correlates with a poor prognosis. Possible therapeutic strategies in patients with EMT include blocking M2 muscarinic receptor signalling, targeting EMT with histone deacetylase inhibitors such as entinostat and MEK-inhibitors such as selumetinib, inhibition of microRNAs, immunotherapy and inhibiting fibroblast growth factor receptor-1.

Mediastinal hepatocellular carcinoma with unknown primary: an unusual and rare presentation

Koh PS, Yusof MM, Yoong BK, Rajadurai P

J Gastrointest Cancer, 2014 Dec;45 Suppl 1:74-6.

PMID: 24045908 DOI: 10.1007/s12029-013-9549-8

Displaying publications 1 - 20 of 35 in total