Lee Yap - Academia.edu (original) (raw)
Papers by Lee Yap
Disease Markers, May 19, 2019
Nasopharyngeal carcinoma (NPC) is a highly metastatic cancer prevalent in Southern China and Sout... more 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.
Undifferentiated nasopharyngeal carcinoma (NPC) is a geographically skewed disease in which more ... more Undifferentiated nasopharyngeal carcinoma (NPC) is a geographically skewed disease in which more than 80% cases are from southern China and Southeast Asia. NPC is consistently associated with Epstein-Barr virus (EBV) infection and characterized by a prominent lymphocyte infiltration. The consistent expression of EBV proteins in NPC cells has led to several clinical trials of adoptive T-cell therapy or vaccination to boost the immune response to EBV antigens. However, these treatments yield relatively modest clinical benefit, which may be due to varying degrees of immunosuppression in the tumor microenvironment. The lack of model systems to analyze the ability of therapeutically relevant T cells to recognize and kill NPC cells represents a fundamental limitation in our attempts to harness the immune system for clinical benefit. We used three NPC cell lines as targets in T-cell assays, together with a panel of established HLA-matched EBV-specific CD8 and CD4 T-cell clones. T-cell activity and killing were measured by IFN-γ ELISA and outgrowth assays, respectively. We demonstrate, for the first time, that NPC cells can be recognized and killed by EBV-specific T-cell clones in vitro, which suggests that tumor-derived factors inhibit such responses in vivo. These observations are consistent with the previous reported functional inactivation of EBV-specific cytotoxic T lymphocytes (CTL) in NPC patients. We hypothesized that EBV infection of NPC cells induces the secretion of immunosuppressive factors. The effect of conditioned media derived from an EBV-infected premalignant nasopharyngeal cell line, NP460htert, on T-cell activity was examined by treating several clones of EBV-specific CTLs in vitro. The conditioned media inhibited the secretion of IFN-γ from peptide-stimulated CTLs, indicating that secreted factors that could suppress CTL functions are induced following EBV infection in NP460htert cells. RNA sequencing analyses on NP460hTert and three NPC cell lines following EBV infection revealed a significant enrichment of genes whose proteins are located at extracellular region/matrix, including a number of immunomodulators. Our results suggest that EBV infection might induce the production of soluble molecules, which in turn suppress the antitumor T-cell responses. In conclusion, we have developed a system with which to study NPC-specific immune responses and shown that soluble factors induced by EBV infection can suppress T-cell activity. These model systems will be critical in the future to examine the effects of checkpoint inhibitors, secreted factors from cancer-associated fibroblasts or NPC cells upon T-cell activity, which will ultimately enhance the success of EBV-targeted immunotherapy strategies. Citation Format: Hui Min Lee, Tracey Haigh, George SW Tsao, Paul G. Murray, Graham Taylor, Ian C. Paterson, Lee Fah Yap. The contribution of Epstein-Barr virus to the impaired T-cell responses in nasopharyngeal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4694.
Nature Communications, Jul 27, 2022
In the Acknowledgements section of this article the grant number relating to Ministry of Higher E... more In the Acknowledgements section of this article the grant number relating to Ministry of Higher Education Malaysia given for Lee-Fah Yap was incorrectly given as FP006-2019A and should have been FRGS/1/2019/SKK08/UM/02/6. The original article has been corrected.
European journal of medicinal chemistry, Mar 1, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Scientific Reports, Oct 16, 2015
It is an urgent need to develop new drugs for Mycobacterium tuberculosis (Mtb), and the enzyme, d... more It is an urgent need to develop new drugs for Mycobacterium tuberculosis (Mtb), and the enzyme, dihydrofolate reductase (DHFR) is a recognised drug target. The crystal structures of methotrexate binding to mt-and h-DHFR separately indicate that the glycerol (GOL) binding site is likely to be critical for the function of mt-DHFR selective inhibitors. We have used in silico methods to screen NCI small molecule database and a group of related compounds were obtained that inhibit mt-DHFR activity and showed bactericidal effects against a test Mtb strain. The binding poses were then analysed and the influence of GOL binding site was studied by using molecular modelling. By comparing the chemical structures, 4 compounds that might be able to occupy the GOL binding site were identified. However, these compounds contain large hydrophobic side chains. As the GOL binding site is more hydrophilic, molecular modelling indicated that these compounds were failed to occupy the GOL site. The most potent inhibitor (compound 6) demonstrated limited selectivity for mt-DHFR, but did contain a novel central core (7H-pyrrolo[3,2-f]quinazoline-1,3-diamine), which may significantly expand the chemical space of novel mt-DHFR inhibitors. Collectively, these observations will inform future medicinal chemistry efforts to improve the selectivity of compounds against mt-DHFR. Tuberculosis (TB) is a deadly infectious disease caused by Mycobacterium tuberculosis (Mtb) that is particularly prevalent in SouthEast Asia and Africa. In 2013, it is estimated that 9 million people developed TB and 1.5 million died from the disease 1. Despite the fact that death from TB is often preventable, the rapid increase of multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis has resulted in an urgent need to develop new drug targets for Mtb 2,3 .
Nature Communications, Jul 7, 2021
Interplay between EBV infection and acquired genetic alterations during nasopharyngeal carcinoma ... more Interplay between EBV infection and acquired genetic alterations during nasopharyngeal carcinoma (NPC) development remains vague. Here we report a comprehensive genomic analysis of 70 NPCs, combining whole-genome sequencing (WGS) of microdissected tumor cells with EBV oncogene expression to reveal multiple aspects of cellular-viral cooperation in tumorigenesis. Genomic aberrations along with EBV-encoded LMP1 expression underpin constitutive NF-κB activation in 90% of NPCs. A similar spectrum of somatic aberrations and viral gene expression undermine innate immunity in 79% of cases and adaptive immunity in 47% of cases; mechanisms by which NPC may evade immune surveillance despite its proinflammatory phenotype. Additionally, genomic changes impairing TGFBR2 promote oncogenesis and stabilize EBV infection in tumor cells. Fine-mapping of CDKN2A/CDKN2B deletion breakpoints reveals homozygous MTAP deletions in 32-34% of NPCs that confer marked sensitivity to MAT2A inhibition. Our work concludes that NPC is a homogeneously NF-κBdriven and immune-protected, yet potentially druggable, cancer.
Cancer Research, May 1, 2009
Oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC) are two distinct types of ... more Oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC) are two distinct types of head and neck cancer (HNC) with very different etiologies; OSCC is caused primarily by tobacco and alcohol and NPC is strongly associated with Epstein Bar virus infection. HNC is a major world health problem and both OSCC and NPC are particularly prevalent in Asian countries. The identification of genes whose expression are de-regulated in both OSCC and NPC would be a significant advance because these genes are likely to be of fundamental importance to the development and progression of HNC in general. Using Affymetrix microarrays, we have compared gene expression in OSCC and NPC with that of the corresponding normal controls. The homeodomain-only protein, HOP, was found to be down-regulated in both tumor types and the results were validated in OSCC/NPC cell lines and tissue samples by RT-PCR and quantitative real-time PCR, respectively. The HOP gene contains two promoters that encode the identical protein via the expression of two transcripts, termed HOP\#945; and HOP\#946;. Treatment of OSCC cells with the DNA demethylating agent, Zebularine, together with the histone deacetylase inhibitor, TSA, restored HOP expression and pyrosequencing analysis of bisulphite treated DNA showed evidence of methylation within the CpG island of the HOP\#946; promoter, suggesting that HOP expression is down-regulated in part by epigenetic mechanisms. In cells where HOP was more readily detected, DNA sequence analysis showed that the coding sequence of HOP was wild type, indicating that HOP is unlikely to be inactivated by mutation. Transfection of HOP into an OSCC cell line resulted in a reduction in colony forming ability and those cells that stably expressed HOP grew significantly slower than vector-transfected controls and were more susceptible to UV-induced apoptosis. In summary, our data demonstrate that HOP functions as a tumor suppressor in OSCC and NPC and indicate that loss of HOP expression may be central to the pathogenesis of HNC by promoting cell proliferation and inhibiting mitochondrial-mediated apoptosis. Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 4352.
Scientific Reports, Jul 26, 2022
Background Nasopharyngeal carcinoma (NPC) is among the most common head and neck malignancies see... more Background Nasopharyngeal carcinoma (NPC) is among the most common head and neck malignancies seen among adults in Malaysia. Therefore, discovery of novel anti-cancer herbal drugs is of importance. In this study, the cytotoxic effect was conducted on a traditional Chinese herbal prescription (Xiao Xian Xiong Decoction (XXXD) that is made up of 3 Chinese herbal medicines, namely Huanglian (Coptidis Rhizome), Banxia (Pinellia Rhizome), Gualuo (Fructus Trichosanthis).Methods The cytotoxic effect of the individual herb and in combination of two and three herbs was studied on 8 nasopharyngeal cancer cell lines. Global gene expression analysis was carried on extracted RNA using nCounter XT Gene Expression Assay.Results TWO-1, TWO-4, HONE-1, SUNE-1, CNE-2, HK-1, CNE-1 and C666-1 treated with Huanglian, the IC50 values obtained were 24.48, 11.77, 4.48, 10.72 6.32, 11.10, 6.77 and 27.30 µg/ml, respectively. For combination of Huanglian and Banxia, the IC50 values obtained were 74.09 µg/ml (T...
PeerJ, 2020
Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide and accounts for 30... more Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide and accounts for 300,000 new cases yearly. The five-year survival rate is approximately 50% and the major challenges to improving patient prognosis include late presentation, treatment resistance, second primary tumours and the lack of targeted therapies. Therefore, there is a compelling need to develop novel therapeutic strategies. In this study, we have examined the effect of lysophosphatidic acid (LPA) on OSCC cell migration, invasion and response to radiation, and investigated the contribution of cyclooxygenase-2 (COX-2) in mediating the tumour promoting effects of LPA. Using the TCGA data set, we show that the expression of the lipid phosphate phosphatases (LPP), LPP1 and LPP3, was significantly down-regulated in OSCC tissues. There was no significant difference in the expression of the ENPP2 gene, which encodes for the enzyme autotaxin (ATX) that produces LPA, between OSCCs and control tissues but EN...
Scientific Reports, 2016
Approximately 20% of global cancer incidence is causally linked to an infectious agent. Epstein-B... more Approximately 20% of global cancer incidence is causally linked to an infectious agent. Epstein-Barr virus (EBV) accounts for around 1% of all virus-associated cancers and is associated with nasopharyngeal carcinoma (NPC). Latent membrane protein 1 (LMP1), the major oncoprotein encoded by EBV, behaves as a constitutively active tumour necrosis factor (TNF) receptor activating a variety of signalling pathways, including the three classic MAPKs (ERK-MAPK, p38 MAPK and JNK/SAPK). The present study identifies novel signalling properties for this integral membrane protein via the induction and secretion of activin A and TGFβ1, which are both required for LMP1’s ability to induce the expression of the extracellular matrix protein, fibronectin. However, it is evident that LMP1 is unable to activate the classic Smad-dependent TGFβ signalling pathway, but rather elicits its effects through the non-Smad arm of TGFβ signalling. In addition, there is a requirement for JNK/SAPK signalling in LMP...
Cancer Research, 2013
Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV) associated malignancy that is parti... more Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV) associated malignancy that is particularly prevalent in Asia. The main challenges in the management of NPC include late presentation and severe side effects of chemo-radiotherapies due to the close proximity of tumours to vital structures. Two bioactive lipids, lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), which signal through G protein-coupled receptors, regulate many biological processes associated with tumour development and progression. Therefore, LPA and S1P have emerged as potential targets in cancer therapies, but the roles of these lipid molecules in the pathogenesis of NPC have not been investigated. Microarray analyses revealed differential expression of several key regulators of LPA and S1P metabolism in NPC cells compared to non-malignant nasopharyngeal epithelium. Imunohistochemical studies showed that autotaxin and SPHK1, the key enzymes involved in the production of LPA and S1P, respectivel...
Cancer Research, 2013
Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide, accounting for mor... more Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide, accounting for more than 250,000 new cases each year. Early death usually occurs as a result of local invasion and regional lymph node metastases and overall five year mortality rates are approximately 50%. Novel therapeutic targets are urgently required. Sphingosine 1-phosphate (S1P) regulates many biological processes associated with tumour development and progression, with the specific effects of S1P being determined, in part, by the profile of receptor expression in tumor cells. Sphingosine kinase 1 (SphK1), an enzyme responsible for the production of S1P, has been reported to be overexpressed in OSCC tissues, but the effect of S1P on the behavior of OSCC cells and the expression of S1P receptors in OSCC has not been examined. The effect of S1P on OSCC cells was examined by treating OSCC cell lines in vitro. S1P inhibited the proliferation of OSCC cells but stimulated cell scattering in colony dispers...
Scientific Reports, Jan 12, 2021
Many of the characteristics ascribed to cancer-associated fibroblasts (CAFs) are shared by activa... more Many of the characteristics ascribed to cancer-associated fibroblasts (CAFs) are shared by activated, autophagic and senescent fibroblasts. Whilst most oral squamous cell carcinomas (OSCCs) are genetically unstable (GU-OSCC), genetically stable variants (GS-OSCC) have been described and, notably, CAF activation (myofibroblast differentiation) and senescence are characteristics particularly associated with GU-OSCCs. However, it is not known whether autophagy is disrupted in these cells or whether autophagy regulates the development of the myofibroblast and senescent phenotypes. In this study, we show that senescent CAFs from GU-OSCCs contained more autophagosomes than normal human oral fibroblasts (NHOFs) and CAFs from GS-OSCCs possibly due to autophagic impairment. Further, we show that deregulation of autophagy in normal fibroblasts, either by inhibition with autophagy inhibitor, SAR405, or activation with TGF-β1, induced fibroblast activation and senescence: In response to TGF-β1, autophagy was induced prior to the development of the activated and senescent phenotypes. Lastly, we show that both SAR405-and TGF-β1-treated NHOFs enhance OSCC cell migration but only TGF-β1-treated cells increase OSCC invasion through Matrigel, indicating that TGF-β1 has additional effects that are independent of fibroblast activation/senescence. These results suggest a functional role for autophagy in the development of myofibroblast and CAF phenotypes.
Oral Diseases, Jan 29, 2015
NOTCH signalling can exert oncogenic or tumour suppressive effects in both solid and haematologic... more NOTCH signalling can exert oncogenic or tumour suppressive effects in both solid and haematological malignancies. Similar to T-cell acute lymphoblastic leukaemia (T-ALL), early studies suggested a pro-tumorigenic role of NOTCH in head and neck squamous cell carcinoma (HNSCC), mainly based on the increased expression levels of the genes within the pathway. Recently, data from exome sequencing analyses unexpectedly pointed to a tumour suppressor role for NOTCH in HNSCC by identifying loss-of-function mutations in the NOTCH1 gene in a significant proportion of patients. These data have questioned the accepted role of NOTCH in HNSCC and the possible rationale of targeting NOTCH in this disease. This review summarises the current information on NOTCH signalling in HNSCC and discusses how this pathway can apparently exert opposing effects within the same disease.
The Journal of general virology, 2014
The relationship between Epstein-Barr virus (EBV) and the germinal centre (GC) of the asymptomati... more The relationship between Epstein-Barr virus (EBV) and the germinal centre (GC) of the asymptomatic host remains an enigma. The occasional appearance of EBV-positive germinal centres in some patients, particularly those with a history of immunosuppression, suggests that EBV numbers in the GC are subject to immune control. The relationship, if any, between lymphoid hyperplasia with EBV-positive germinal centres and subsequent or concurrent lymphomagenesis remains to be clarified. As far as the development of EBV-associated Hodgkin's lymphoma is concerned, the suppression of virus replication, mediated by LMP1 on the one hand, and the loss of B-cell receptor signalling on the other, appears to be an important pathogenic mechanism. A further important emerging concept is that alterations in the microenvironment of the EBV-infected B-cell may be important for lymphomagenesis.
Proceedings of the …, 2006
The genetic changes underlying oral carcinogenesis are starting to be elucidated, but there is st... more The genetic changes underlying oral carcinogenesis are starting to be elucidated, but there is still limited information on the precise nature of those genes that specifically promote the development and progression of oral squamous cell carcinoma (OSCC). We have used Affymetrix high-...
PeerJ, 2020
Head and neck squamous cell carcinoma (HNSCC) represents a significant world health problem, with... more Head and neck squamous cell carcinoma (HNSCC) represents a significant world health problem, with approximately 600,000 new cases being diagnosed annually. The prognosis for patients with HNSCC is poor and, therefore, the identification of biomarkers for screening, diagnosis and prognostication would be clinically beneficial. A limited number of studies have used lipidomics to profile lipid species in the plasma of cancer patients. However, the profile and levels of lysophosphatidic acid (LPA) species have not been examined in HNSCC. In this study, a targeted lipidomics approach using liquid chromatography triple quadrupole mass spectrometry (LCMS/MS) was used to analyse the concentration of LPA (16:0 LPA, 18:0 LPA, 18:1 LPA, 18:2 LPA and 20:4 LPA) in the plasma of patients with oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC), together with healthy controls. The levels of three LPA species (18:1 LPA, 18:2 LPA and 20:4 LPA) were significantly lower in the plasm...
Molecular Carcinogenesis, 2011
Nasopharyngeal carcinoma (NPC) is a multifactorial and polygenic disease with high incidence in A... more Nasopharyngeal carcinoma (NPC) is a multifactorial and polygenic disease with high incidence in Asian countries. Epstein-Barr virus infection, environmental and genetic factors are believed to be involved in the tumorigenesis of NPC. The association of single nucleotide polymorphisms (SNPs) in LPLUNC1 and SPLUNC1 genes with NPC was investigated by performing a two-stage case control association study in a Malaysian Chinese population. The initial screening consisted of 81 NPC patients and 147 healthy controls while the replication study consisted of 366 NPC patients and 340 healthy controls. The combined analysis showed that a SNP (rs2752903) of SPLUNC1 was significantly associated with the risk of NPC (combined P ¼ 0.00032, odds ratio ¼ 1.62, 95% confidence interval ¼ 1.25-2.11). In the subsequent dense fine mapping of SPLUNC1 locus, 36 SNPs in strong linkage disequilibrium with rs2752903 (r 2 ! 0.85) were associated with NPC susceptibility. Screening of these variants by electrophoretic mobility shift and luciferase reporter assays showed that rs1407019 located in intron 3 (r 2 ¼ 0.994 with rs2752903) caused allelic difference in the binding of specificity protein 1 (Sp1) transcription factor and affected luciferase activity. This SNP may consequently alter the expression of SPLUNC1 in the epithelial cells. In summary, our study suggested that rs1407019
International Journal of Cancer, 2014
Disease Markers, May 19, 2019
Nasopharyngeal carcinoma (NPC) is a highly metastatic cancer prevalent in Southern China and Sout... more 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.
Undifferentiated nasopharyngeal carcinoma (NPC) is a geographically skewed disease in which more ... more Undifferentiated nasopharyngeal carcinoma (NPC) is a geographically skewed disease in which more than 80% cases are from southern China and Southeast Asia. NPC is consistently associated with Epstein-Barr virus (EBV) infection and characterized by a prominent lymphocyte infiltration. The consistent expression of EBV proteins in NPC cells has led to several clinical trials of adoptive T-cell therapy or vaccination to boost the immune response to EBV antigens. However, these treatments yield relatively modest clinical benefit, which may be due to varying degrees of immunosuppression in the tumor microenvironment. The lack of model systems to analyze the ability of therapeutically relevant T cells to recognize and kill NPC cells represents a fundamental limitation in our attempts to harness the immune system for clinical benefit. We used three NPC cell lines as targets in T-cell assays, together with a panel of established HLA-matched EBV-specific CD8 and CD4 T-cell clones. T-cell activity and killing were measured by IFN-γ ELISA and outgrowth assays, respectively. We demonstrate, for the first time, that NPC cells can be recognized and killed by EBV-specific T-cell clones in vitro, which suggests that tumor-derived factors inhibit such responses in vivo. These observations are consistent with the previous reported functional inactivation of EBV-specific cytotoxic T lymphocytes (CTL) in NPC patients. We hypothesized that EBV infection of NPC cells induces the secretion of immunosuppressive factors. The effect of conditioned media derived from an EBV-infected premalignant nasopharyngeal cell line, NP460htert, on T-cell activity was examined by treating several clones of EBV-specific CTLs in vitro. The conditioned media inhibited the secretion of IFN-γ from peptide-stimulated CTLs, indicating that secreted factors that could suppress CTL functions are induced following EBV infection in NP460htert cells. RNA sequencing analyses on NP460hTert and three NPC cell lines following EBV infection revealed a significant enrichment of genes whose proteins are located at extracellular region/matrix, including a number of immunomodulators. Our results suggest that EBV infection might induce the production of soluble molecules, which in turn suppress the antitumor T-cell responses. In conclusion, we have developed a system with which to study NPC-specific immune responses and shown that soluble factors induced by EBV infection can suppress T-cell activity. These model systems will be critical in the future to examine the effects of checkpoint inhibitors, secreted factors from cancer-associated fibroblasts or NPC cells upon T-cell activity, which will ultimately enhance the success of EBV-targeted immunotherapy strategies. Citation Format: Hui Min Lee, Tracey Haigh, George SW Tsao, Paul G. Murray, Graham Taylor, Ian C. Paterson, Lee Fah Yap. The contribution of Epstein-Barr virus to the impaired T-cell responses in nasopharyngeal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4694.
Nature Communications, Jul 27, 2022
In the Acknowledgements section of this article the grant number relating to Ministry of Higher E... more In the Acknowledgements section of this article the grant number relating to Ministry of Higher Education Malaysia given for Lee-Fah Yap was incorrectly given as FP006-2019A and should have been FRGS/1/2019/SKK08/UM/02/6. The original article has been corrected.
European journal of medicinal chemistry, Mar 1, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Scientific Reports, Oct 16, 2015
It is an urgent need to develop new drugs for Mycobacterium tuberculosis (Mtb), and the enzyme, d... more It is an urgent need to develop new drugs for Mycobacterium tuberculosis (Mtb), and the enzyme, dihydrofolate reductase (DHFR) is a recognised drug target. The crystal structures of methotrexate binding to mt-and h-DHFR separately indicate that the glycerol (GOL) binding site is likely to be critical for the function of mt-DHFR selective inhibitors. We have used in silico methods to screen NCI small molecule database and a group of related compounds were obtained that inhibit mt-DHFR activity and showed bactericidal effects against a test Mtb strain. The binding poses were then analysed and the influence of GOL binding site was studied by using molecular modelling. By comparing the chemical structures, 4 compounds that might be able to occupy the GOL binding site were identified. However, these compounds contain large hydrophobic side chains. As the GOL binding site is more hydrophilic, molecular modelling indicated that these compounds were failed to occupy the GOL site. The most potent inhibitor (compound 6) demonstrated limited selectivity for mt-DHFR, but did contain a novel central core (7H-pyrrolo[3,2-f]quinazoline-1,3-diamine), which may significantly expand the chemical space of novel mt-DHFR inhibitors. Collectively, these observations will inform future medicinal chemistry efforts to improve the selectivity of compounds against mt-DHFR. Tuberculosis (TB) is a deadly infectious disease caused by Mycobacterium tuberculosis (Mtb) that is particularly prevalent in SouthEast Asia and Africa. In 2013, it is estimated that 9 million people developed TB and 1.5 million died from the disease 1. Despite the fact that death from TB is often preventable, the rapid increase of multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis has resulted in an urgent need to develop new drug targets for Mtb 2,3 .
Nature Communications, Jul 7, 2021
Interplay between EBV infection and acquired genetic alterations during nasopharyngeal carcinoma ... more Interplay between EBV infection and acquired genetic alterations during nasopharyngeal carcinoma (NPC) development remains vague. Here we report a comprehensive genomic analysis of 70 NPCs, combining whole-genome sequencing (WGS) of microdissected tumor cells with EBV oncogene expression to reveal multiple aspects of cellular-viral cooperation in tumorigenesis. Genomic aberrations along with EBV-encoded LMP1 expression underpin constitutive NF-κB activation in 90% of NPCs. A similar spectrum of somatic aberrations and viral gene expression undermine innate immunity in 79% of cases and adaptive immunity in 47% of cases; mechanisms by which NPC may evade immune surveillance despite its proinflammatory phenotype. Additionally, genomic changes impairing TGFBR2 promote oncogenesis and stabilize EBV infection in tumor cells. Fine-mapping of CDKN2A/CDKN2B deletion breakpoints reveals homozygous MTAP deletions in 32-34% of NPCs that confer marked sensitivity to MAT2A inhibition. Our work concludes that NPC is a homogeneously NF-κBdriven and immune-protected, yet potentially druggable, cancer.
Cancer Research, May 1, 2009
Oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC) are two distinct types of ... more Oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC) are two distinct types of head and neck cancer (HNC) with very different etiologies; OSCC is caused primarily by tobacco and alcohol and NPC is strongly associated with Epstein Bar virus infection. HNC is a major world health problem and both OSCC and NPC are particularly prevalent in Asian countries. The identification of genes whose expression are de-regulated in both OSCC and NPC would be a significant advance because these genes are likely to be of fundamental importance to the development and progression of HNC in general. Using Affymetrix microarrays, we have compared gene expression in OSCC and NPC with that of the corresponding normal controls. The homeodomain-only protein, HOP, was found to be down-regulated in both tumor types and the results were validated in OSCC/NPC cell lines and tissue samples by RT-PCR and quantitative real-time PCR, respectively. The HOP gene contains two promoters that encode the identical protein via the expression of two transcripts, termed HOP\#945; and HOP\#946;. Treatment of OSCC cells with the DNA demethylating agent, Zebularine, together with the histone deacetylase inhibitor, TSA, restored HOP expression and pyrosequencing analysis of bisulphite treated DNA showed evidence of methylation within the CpG island of the HOP\#946; promoter, suggesting that HOP expression is down-regulated in part by epigenetic mechanisms. In cells where HOP was more readily detected, DNA sequence analysis showed that the coding sequence of HOP was wild type, indicating that HOP is unlikely to be inactivated by mutation. Transfection of HOP into an OSCC cell line resulted in a reduction in colony forming ability and those cells that stably expressed HOP grew significantly slower than vector-transfected controls and were more susceptible to UV-induced apoptosis. In summary, our data demonstrate that HOP functions as a tumor suppressor in OSCC and NPC and indicate that loss of HOP expression may be central to the pathogenesis of HNC by promoting cell proliferation and inhibiting mitochondrial-mediated apoptosis. Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 4352.
Scientific Reports, Jul 26, 2022
Background Nasopharyngeal carcinoma (NPC) is among the most common head and neck malignancies see... more Background Nasopharyngeal carcinoma (NPC) is among the most common head and neck malignancies seen among adults in Malaysia. Therefore, discovery of novel anti-cancer herbal drugs is of importance. In this study, the cytotoxic effect was conducted on a traditional Chinese herbal prescription (Xiao Xian Xiong Decoction (XXXD) that is made up of 3 Chinese herbal medicines, namely Huanglian (Coptidis Rhizome), Banxia (Pinellia Rhizome), Gualuo (Fructus Trichosanthis).Methods The cytotoxic effect of the individual herb and in combination of two and three herbs was studied on 8 nasopharyngeal cancer cell lines. Global gene expression analysis was carried on extracted RNA using nCounter XT Gene Expression Assay.Results TWO-1, TWO-4, HONE-1, SUNE-1, CNE-2, HK-1, CNE-1 and C666-1 treated with Huanglian, the IC50 values obtained were 24.48, 11.77, 4.48, 10.72 6.32, 11.10, 6.77 and 27.30 µg/ml, respectively. For combination of Huanglian and Banxia, the IC50 values obtained were 74.09 µg/ml (T...
PeerJ, 2020
Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide and accounts for 30... more Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide and accounts for 300,000 new cases yearly. The five-year survival rate is approximately 50% and the major challenges to improving patient prognosis include late presentation, treatment resistance, second primary tumours and the lack of targeted therapies. Therefore, there is a compelling need to develop novel therapeutic strategies. In this study, we have examined the effect of lysophosphatidic acid (LPA) on OSCC cell migration, invasion and response to radiation, and investigated the contribution of cyclooxygenase-2 (COX-2) in mediating the tumour promoting effects of LPA. Using the TCGA data set, we show that the expression of the lipid phosphate phosphatases (LPP), LPP1 and LPP3, was significantly down-regulated in OSCC tissues. There was no significant difference in the expression of the ENPP2 gene, which encodes for the enzyme autotaxin (ATX) that produces LPA, between OSCCs and control tissues but EN...
Scientific Reports, 2016
Approximately 20% of global cancer incidence is causally linked to an infectious agent. Epstein-B... more Approximately 20% of global cancer incidence is causally linked to an infectious agent. Epstein-Barr virus (EBV) accounts for around 1% of all virus-associated cancers and is associated with nasopharyngeal carcinoma (NPC). Latent membrane protein 1 (LMP1), the major oncoprotein encoded by EBV, behaves as a constitutively active tumour necrosis factor (TNF) receptor activating a variety of signalling pathways, including the three classic MAPKs (ERK-MAPK, p38 MAPK and JNK/SAPK). The present study identifies novel signalling properties for this integral membrane protein via the induction and secretion of activin A and TGFβ1, which are both required for LMP1’s ability to induce the expression of the extracellular matrix protein, fibronectin. However, it is evident that LMP1 is unable to activate the classic Smad-dependent TGFβ signalling pathway, but rather elicits its effects through the non-Smad arm of TGFβ signalling. In addition, there is a requirement for JNK/SAPK signalling in LMP...
Cancer Research, 2013
Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV) associated malignancy that is parti... more Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV) associated malignancy that is particularly prevalent in Asia. The main challenges in the management of NPC include late presentation and severe side effects of chemo-radiotherapies due to the close proximity of tumours to vital structures. Two bioactive lipids, lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), which signal through G protein-coupled receptors, regulate many biological processes associated with tumour development and progression. Therefore, LPA and S1P have emerged as potential targets in cancer therapies, but the roles of these lipid molecules in the pathogenesis of NPC have not been investigated. Microarray analyses revealed differential expression of several key regulators of LPA and S1P metabolism in NPC cells compared to non-malignant nasopharyngeal epithelium. Imunohistochemical studies showed that autotaxin and SPHK1, the key enzymes involved in the production of LPA and S1P, respectivel...
Cancer Research, 2013
Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide, accounting for mor... more Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide, accounting for more than 250,000 new cases each year. Early death usually occurs as a result of local invasion and regional lymph node metastases and overall five year mortality rates are approximately 50%. Novel therapeutic targets are urgently required. Sphingosine 1-phosphate (S1P) regulates many biological processes associated with tumour development and progression, with the specific effects of S1P being determined, in part, by the profile of receptor expression in tumor cells. Sphingosine kinase 1 (SphK1), an enzyme responsible for the production of S1P, has been reported to be overexpressed in OSCC tissues, but the effect of S1P on the behavior of OSCC cells and the expression of S1P receptors in OSCC has not been examined. The effect of S1P on OSCC cells was examined by treating OSCC cell lines in vitro. S1P inhibited the proliferation of OSCC cells but stimulated cell scattering in colony dispers...
Scientific Reports, Jan 12, 2021
Many of the characteristics ascribed to cancer-associated fibroblasts (CAFs) are shared by activa... more Many of the characteristics ascribed to cancer-associated fibroblasts (CAFs) are shared by activated, autophagic and senescent fibroblasts. Whilst most oral squamous cell carcinomas (OSCCs) are genetically unstable (GU-OSCC), genetically stable variants (GS-OSCC) have been described and, notably, CAF activation (myofibroblast differentiation) and senescence are characteristics particularly associated with GU-OSCCs. However, it is not known whether autophagy is disrupted in these cells or whether autophagy regulates the development of the myofibroblast and senescent phenotypes. In this study, we show that senescent CAFs from GU-OSCCs contained more autophagosomes than normal human oral fibroblasts (NHOFs) and CAFs from GS-OSCCs possibly due to autophagic impairment. Further, we show that deregulation of autophagy in normal fibroblasts, either by inhibition with autophagy inhibitor, SAR405, or activation with TGF-β1, induced fibroblast activation and senescence: In response to TGF-β1, autophagy was induced prior to the development of the activated and senescent phenotypes. Lastly, we show that both SAR405-and TGF-β1-treated NHOFs enhance OSCC cell migration but only TGF-β1-treated cells increase OSCC invasion through Matrigel, indicating that TGF-β1 has additional effects that are independent of fibroblast activation/senescence. These results suggest a functional role for autophagy in the development of myofibroblast and CAF phenotypes.
Oral Diseases, Jan 29, 2015
NOTCH signalling can exert oncogenic or tumour suppressive effects in both solid and haematologic... more NOTCH signalling can exert oncogenic or tumour suppressive effects in both solid and haematological malignancies. Similar to T-cell acute lymphoblastic leukaemia (T-ALL), early studies suggested a pro-tumorigenic role of NOTCH in head and neck squamous cell carcinoma (HNSCC), mainly based on the increased expression levels of the genes within the pathway. Recently, data from exome sequencing analyses unexpectedly pointed to a tumour suppressor role for NOTCH in HNSCC by identifying loss-of-function mutations in the NOTCH1 gene in a significant proportion of patients. These data have questioned the accepted role of NOTCH in HNSCC and the possible rationale of targeting NOTCH in this disease. This review summarises the current information on NOTCH signalling in HNSCC and discusses how this pathway can apparently exert opposing effects within the same disease.
The Journal of general virology, 2014
The relationship between Epstein-Barr virus (EBV) and the germinal centre (GC) of the asymptomati... more The relationship between Epstein-Barr virus (EBV) and the germinal centre (GC) of the asymptomatic host remains an enigma. The occasional appearance of EBV-positive germinal centres in some patients, particularly those with a history of immunosuppression, suggests that EBV numbers in the GC are subject to immune control. The relationship, if any, between lymphoid hyperplasia with EBV-positive germinal centres and subsequent or concurrent lymphomagenesis remains to be clarified. As far as the development of EBV-associated Hodgkin's lymphoma is concerned, the suppression of virus replication, mediated by LMP1 on the one hand, and the loss of B-cell receptor signalling on the other, appears to be an important pathogenic mechanism. A further important emerging concept is that alterations in the microenvironment of the EBV-infected B-cell may be important for lymphomagenesis.
Proceedings of the …, 2006
The genetic changes underlying oral carcinogenesis are starting to be elucidated, but there is st... more The genetic changes underlying oral carcinogenesis are starting to be elucidated, but there is still limited information on the precise nature of those genes that specifically promote the development and progression of oral squamous cell carcinoma (OSCC). We have used Affymetrix high-...
PeerJ, 2020
Head and neck squamous cell carcinoma (HNSCC) represents a significant world health problem, with... more Head and neck squamous cell carcinoma (HNSCC) represents a significant world health problem, with approximately 600,000 new cases being diagnosed annually. The prognosis for patients with HNSCC is poor and, therefore, the identification of biomarkers for screening, diagnosis and prognostication would be clinically beneficial. A limited number of studies have used lipidomics to profile lipid species in the plasma of cancer patients. However, the profile and levels of lysophosphatidic acid (LPA) species have not been examined in HNSCC. In this study, a targeted lipidomics approach using liquid chromatography triple quadrupole mass spectrometry (LCMS/MS) was used to analyse the concentration of LPA (16:0 LPA, 18:0 LPA, 18:1 LPA, 18:2 LPA and 20:4 LPA) in the plasma of patients with oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC), together with healthy controls. The levels of three LPA species (18:1 LPA, 18:2 LPA and 20:4 LPA) were significantly lower in the plasm...
Molecular Carcinogenesis, 2011
Nasopharyngeal carcinoma (NPC) is a multifactorial and polygenic disease with high incidence in A... more Nasopharyngeal carcinoma (NPC) is a multifactorial and polygenic disease with high incidence in Asian countries. Epstein-Barr virus infection, environmental and genetic factors are believed to be involved in the tumorigenesis of NPC. The association of single nucleotide polymorphisms (SNPs) in LPLUNC1 and SPLUNC1 genes with NPC was investigated by performing a two-stage case control association study in a Malaysian Chinese population. The initial screening consisted of 81 NPC patients and 147 healthy controls while the replication study consisted of 366 NPC patients and 340 healthy controls. The combined analysis showed that a SNP (rs2752903) of SPLUNC1 was significantly associated with the risk of NPC (combined P ¼ 0.00032, odds ratio ¼ 1.62, 95% confidence interval ¼ 1.25-2.11). In the subsequent dense fine mapping of SPLUNC1 locus, 36 SNPs in strong linkage disequilibrium with rs2752903 (r 2 ! 0.85) were associated with NPC susceptibility. Screening of these variants by electrophoretic mobility shift and luciferase reporter assays showed that rs1407019 located in intron 3 (r 2 ¼ 0.994 with rs2752903) caused allelic difference in the binding of specificity protein 1 (Sp1) transcription factor and affected luciferase activity. This SNP may consequently alter the expression of SPLUNC1 in the epithelial cells. In summary, our study suggested that rs1407019
International Journal of Cancer, 2014