Displaying publications 1 - 20 of 35 in total

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  1. Chai AWY, Yee SM, Lee HM, Abdul Aziz N, Yee PS, Marzuki M, et al.
    Cancer Res Commun, 2024 Mar 04;4(3):645-659.
    PMID: 38358347 DOI: 10.1158/2767-9764.CRC-23-0341
    Nasopharyngeal carcinoma (NPC), a cancer that is etiologically associated with the Epstein-Barr virus (EBV), is endemic in Southern China and Southeast Asia. The scarcity of representative NPC cell lines owing to the frequent loss of EBV episomes following prolonged propagation and compromised authenticity of previous models underscores the critical need for new EBV-positive NPC models. Herein, we describe the establishment of a new EBV-positive NPC cell line, designated NPC268 from a primary non-keratinizing, differentiated NPC tissue. NPC268 can undergo productive lytic reactivation of EBV and is highly tumorigenic in immunodeficient mice. Whole-genome sequencing revealed close similarities with the tissue of origin, including large chromosomal rearrangements, while whole-genome bisulfite sequencing and RNA sequencing demonstrated a hypomethylated genome and enrichment in immune-related pathways, respectively. Drug screening of NPC268 together with six other NPC cell lines using 339 compounds, representing the largest high-throughput drug testing in NPC, revealed biomarkers associated with specific drug classes. NPC268 represents the first and only available EBV-positive non-keratinizing differentiated NPC model, and extensive genomic, methylomic, transcriptomic, and drug response data should facilitate research in EBV and NPC, where current models are limited.

    SIGNIFICANCE: NPC268 is the first and only EBV-positive cell line derived from a primary non-keratinizing, differentiated nasopharyngeal carcinoma, an understudied but important subtype in Southeast Asian countries. This model adds to the limited number of authentic EBV-positive lines globally that will facilitate mechanistic studies and drug development for NPC.

  2. Chai SJ, Ahmad Zabidi MM, Gan SP, Rajadurai P, Lim PVH, Ng CC, et al.
    Dis Markers, 2019;2019:3857853.
    PMID: 31236144 DOI: 10.1155/2019/3857853
    Nasopharyngeal carcinoma (NPC) is a highly metastatic cancer prevalent in Southern China and Southeast Asia. The current knowledge on the molecular pathogenesis of NPC is still inadequate to improve disease management. Using gene expression microarrays, we have identified the four-jointed box 1 (FJX1) gene to be upregulated in primary NPC tissues relative to nonmalignant tissues. An orthologue of human FJX1, the four-jointed (fj) gene in Drosophila and Fjx1 in mouse, has reported to be associated with cancer progression pathways. However, the exact function of FJX1 in human is not well characterized. The overexpression of FJX1 mRNA was validated in primary NPC tissue samples, and the level of FJX1 protein was significantly higher in a subset of NPC tissues (42%) compared to the normal epithelium, where no expression of FJX1 was observed (p = 0.01). FJX1 is also found to be overexpressed in microarray datasets and TCGA datasets of other cancers including head and neck cancer, colorectal, and ovarian cancer. Both siRNA knockdown and overexpression experiments in NPC cell lines showed that FJX1 promotes cell proliferation, anchorage-dependent growth, and cellular invasion. Cyclin D1 and E1 mRNA levels were increased following FJX1 expression indicating that FJX1 enhances proliferation by regulating key proteins governing the cell cycle. Our data suggest that the overexpression of FJX1 contributes to a more aggressive phenotype of NPC cells and further investigations into FJX1 as a potential therapeutic target for NPC are warranted. The evaluation of FJX1 as an immunotherapy target for NPC and other cancers is currently ongoing.
  3. 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.
  4. Khajotia R, Raman S, Rajadurai P, Yaacob W
    Aust Fam Physician, 2010 Apr;39(4):219-20.
    PMID: 20372682
  5. 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.
  6. Lee YQ, Rajadurai P, Abas F, Othman I, Naidu R
    Front Mol Biosci, 2021;8:645856.
    PMID: 33996900 DOI: 10.3389/fmolb.2021.645856
    Curcumin analogs with excellent biological properties have been synthesized to address and overcome the poor pharmacokinetic profiles of curcumin. This study aims to investigate the cytotoxicity, anti-proliferative, and apoptosis-inducing ability of curcumin analog, MS13 on human glioblastoma U-87 MG, and neuroblastoma SH-SY5Y cells, and to examine the global proteome changes in these cells following treatment. Our current findings showed that MS13 induced potent cytotoxicity and anti-proliferative effects on both cells. Increased caspase-3 activity and decreased bcl-2 concentration upon treatment indicate that MS13 induces apoptosis in these cells in a dose- and time-dependent manner. The label-free shotgun proteomic analysis has defined the protein profiles in both glioblastoma and neuroblastoma cells, whereby a total of nine common DEPs, inclusive of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), alpha-enolase (ENO1), heat shock protein HSP 90-alpha (HSP90AA1), Heat shock protein HSP 90-beta (HSP90AB1), Eukaryotic translation initiation factor 5A-1 (EFI5A), heterogenous nuclear ribonucleoprotein K (HNRNPK), tubulin beta chain (TUBB), histone H2AX (H2AFX), and Protein SET were identified. Pathway analysis further elucidated that MS13 may induce its anti-tumor effects in both cells via the common enriched pathways, "Glycolysis" and "Post-translational protein modification." Conclusively, MS13 demonstrates an anti-cancer effect that may indicate its potential use in the management of brain malignancies.
  7. 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.].
  8. 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.
  9. Liam CK, Leow HR, How SH, Pang YK, Chua KT, Lim BK, et al.
    Asian Pac J Cancer Prev, 2014;15(1):321-6.
    PMID: 24528049
    BACKGROUND: Mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) in non- small cell lung cancer (NSCLC) are predictive of response to EGFR-targeted therapy in advanced stages of disease. This study aimed to determine the frequency of EGFR mutations in NSCLCs and to correlate their presence with clinical characteristics in multiethnic Malaysian patients.

    MATERIALS AND METHODS: In this prospective study, EGFR mutations in exons 18, 19, 20 and 21 in formalin-fixed paraffin-embedded biopsy specimens of consecutive NSCLC patients were asessed by real-time polymerase chain reaction.

    RESULTS: EGFR mutations were detected in NSCLCs from 55 (36.4%) of a total of 151 patients, being significantly more common in females (62.5%) than in males (17.2%) [odds ratio (OR), 8.00; 95% confidence interval (CI), 3.77-16.98; p<0.001] and in never smokers (62.5%) than in ever smokers (12.7%) (OR, 11.50; 95%CI, 5.08-26.03; p<0.001). Mutations were more common in adenocarcinoma (39.4%) compared to non-adenocarcinoma NSCLCs (15.8%) (p=0.072). The mutation rates in patients of different ethnicities were not significantly different (p=0.08). Never smoking status was the only clinical feature that independently predicted the presence of EGFR mutations (adjusted OR, 5.94; 95%CI, 1.94- 18.17; p=0.002).

    CONCLUSIONS: In Malaysian patients with NSCLC, the EGFR mutation rate was similar to that in other Asian populations. EGFR mutations were significantly more common in female patients and in never smokers. Never smoking status was the only independent predictor for the presence of EGFR mutations.

  10. 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.
  11. Masood Y, Kqueen CY, Rajadurai P
    Expert Rev Anticancer Ther, 2015 Feb;15(2):183-97.
    PMID: 25367254 DOI: 10.1586/14737140.2015.978294
    Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide. Evidence suggests that miRNAs play an important role in progression, recurrence, metastasis and postoperative survival of HNSCC. Studies have investigated the utility of miRNAs as diagnostic/prognostic tools and as potential therapeutic targets and biomarkers that may improve the management and outcomes of HNSCC. The aim of this article is to review the current literature on aberrant expression profiles of miRNAs in biopsy samples of HNSCC and their role in cancer development, metastasis, prognosis and survival of these patients. This review gives an overview that miRNAs deregulation play major role in the development of HNSCC. They offer the potential to be used as biomarkers or novel therapeutic targets. Future research is required to test their use in both of these fields.
  12. Md Pauzi SH, Masir N, Yahaya A, Mohammed F, Tizen Laim NMS, Mustangin M, et al.
    Indian J Pathol Microbiol, 2021 10 22;64(4):677-682.
    PMID: 34673585 DOI: 10.4103/IJPM.IJPM_983_20
    Background: Human epidermal growth factor receptor 2 (HER2) over-expression in breast cancer is associated with aggressive tumor behavior and predicts response to targeted therapy. Accurate HER2 result is paramount for optimal patient management. However, routine HER2 immunohistochemistry (IHC) testing are subjected to intra- and inter-laboratory variability.

    Objective: This study aims to determine inter-laboratory variation in HER2 IHC testing through a slide-exchange program between five main reference laboratories.

    Method: A total of 20 breast carcinoma cases with different known HER2 expression and gene status were selected by the central laboratory in five testing rounds. Three unstained tissue sections from each case were sent to participating laboratories, which immunostained and interpreted the HER2 immunohistochemistry result. One of the stained slides was sent to one designated participating laboratory for evaluation. Results were analyzed by the central laboratory.

    Results: A complete concordance was achieved in six IHC-positive and six IHC-negative cases, its gene status of which was confirmed by in-situ-hybridization (ISH) study. The discordant results were observed in six equivocal cases, one negative case and one positive case with a concordance rate of 50-88.3%. Interestingly, the negative discordant case actually displays tumor heterogeneity. Good inter-observer agreement was achieved for all participating laboratories (k = 0.713-1.0).

    Conclusion: Standardization of HER2 testing method is important to achieve optimum inter-laboratory concordance. Discordant results were seen mainly in equivocal cases. Intra-tumoral heterogeneity may impact the final HER2 IHC scoring. The continuous quality evaluation is therefore paramount to achieve reliable HER2 results.

  13. Mohamad N, Jayalakshmi P, Rhodes A, Liam CK, Tan JL, Yousoof S, et al.
    Br J Biomed Sci, 2017 Oct;74(4):176-180.
    PMID: 28705139 DOI: 10.1080/09674845.2017.1331520
    BACKGROUND: Non-small cell lung cancer (NSCLC) is a major cause of cancer-related death. Approximately 2-16% of NSCLC patients with wild-type epidermal growth factor receptor (EGFR) harbour anaplastic lymphoma kinase (ALK) mutations. Both EGFR and ALK mutations occur most commonly in Asian patients with NSCLC. As targeted therapy is available for NSCLC patients with these mutations, it is important to establish reliable assays and testing strategies to identify those most likely to benefit from this therapy.

    MATERIALS AND METHODS: Patients diagnosed with adenocarcinoma of the lung between 2010 and 2014 were tested for EGFR mutations. Of these, 92 cases were identified as EGFR wild type and suitable candidates for ALK testing utilising immunohistochemistry and the rabbit monoclonal antibody D5F3. The reliability of the IHC was confirmed by validating the results against those achieved by fluorescence in situ hybridisation (FISH) to detect ALK gene rearrangements.

    RESULTS: Twelve (13%) cases were positive for ALK expression using immunohistochemistry. Of the 18 evaluable cases tested by FISH, there was 100% agreement with respect to ALK rearrangement/ALK expression between the assays, with 11 cases ALK negative and 7 cases ALK positive by both assays. ALK tumour expression was significantly more common in female compared to male patients (29.6% vs. 6.2%, P P P = 0.047).

    CONCLUSIONS: Detection of ALK expression by IHC is reliable and the most practical way of identifying NSCLC patients likely to benefit from crizotinib treatment.

  14. 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.
  15. 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
  16. 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.
  17. Pan JW, Zabidi MMA, Chong BK, Meng MY, Ng PS, Hasan SN, et al.
    Int J Cancer, 2021 May 15;148(10):2489-2501.
    PMID: 33423300 DOI: 10.1002/ijc.33463
    A 30-kb deletion that eliminates the coding region of APOBEC3B (A3B) is >5 times more common in women of Asian descent compared to European descent. This polymorphism creates a chimera with the APOBEC3A (A3A) coding region and A3B 3'UTR, and it is associated with an increased risk for breast cancer in Asian women. Here, we explored the relationship between the A3B deletion polymorphism with tumour characteristics in Asian women. Using whole exome and whole transcriptome sequencing data of 527 breast tumours, we report that germline A3B deletion polymorphism leads to expression of the A3A-B hybrid isoform and increased APOBEC-associated somatic hypermutation. Hypermutated tumours, regardless of A3B germline status, were associated with the Her2 molecular subtype and PIK3CA mutations. Compared to nonhypermutated tumours, hypermutated tumours also had higher neoantigen burden, tumour heterogeneity and immune activation. Taken together, our results suggest that the germline A3B deletion polymorphism, via the A3A-B hybrid isoform, contributes to APOBEC mutagenesis in a significant proportion of Asian breast cancers. In addition, APOBEC somatic hypermutation, regardless of A3B background, may be an important clinical biomarker for Asian breast cancers.
  18. 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.
  19. Prasad U, bin Jalaludin MA, Rajadurai P, Pizza G, De Vinci C, Viza D, et al.
    Biotherapy, 1996;9(1-3):109-15.
    PMID: 8993768
    Overall survival of nasopharyngeal carcinoma (NPC) at UICC stage IV still remains unsatisfactory even with combination chemotherapy (CT) and radio-therapy (RT). In view of the association of reactivation of Epstein-Barr virus (EBV) with the development and recurrence of NPC, immunotherapy in the form of transfer factor (TF) with specific activity against EBV (TF-B1) was suggested as an adjuvant to a combination of CT and RT in order to improve survival. In the present study, 6 UICC stage IV patients received TF-B1 and another 6 patients matched for disease stage were given TF prepared from peripheral blood leucocytes (TF-PBL). Results were compared with another 18 patients matched by age, sex, and stage of disease who received standard therapy without TF during the same period (C group). After a median follow up of 47.5 months, the survival for the TF-B1 group was found to be significantly better (P = < 0.05) than the PBL and C group. While the 8 patients with distant metastasis (DM), not treated with TF-B1 (6 in the control and 2 in the PBL group), died due to progressive disease (average survival being 14.3 months), both patients with DM in the TF-B1 group had complete remission: one died of tuberculosis after surviving for 3.5 years and another is still alive, disease free, after 4.2 years. Although the series involved a small number of cases, the apparent effect of adjuvant immunotherapy in the form of TF with anti-EBV activity is of considerable interest.
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