Displaying publications 1 - 20 of 32 in total

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  1. Fulltext Regulation of apoptotic effects by erythrocarpine E, a cytotoxic limonoid from Chisocheton erythrocarpus in HSC-4 human oral cancer cells
    Nagoor NH, Shah Jehan Muttiah N, Lim CS, In LL, Mohamad K, Awang K
    PLoS One, 2011;6(8):e23661.
    PMID: 21858194 DOI: 10.1371/journal.pone.0023661
    The aim of this study was to determine the cytotoxic and apoptotic effects of erythrocarpine E (CEB4), a limonoid extracted from Chisocheton erythrocarpus on human oral squamous cell carcinoma. Based on preliminary dimethyl-2-thiazolyl-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays, CEB4 treated HSC-4 cells demonstrated a cytotoxic effect and inhibited cell proliferation in a time and dose dependent manner with an IC(50) value of 4.0±1.9 µM within 24 h of treatment. CEB4 was also found to have minimal cytotoxic effects on the normal cell line, NHBE with cell viability levels maintained above 80% upon treatment. Annexin V-fluorescein isothiocyanate (FITC), poly-ADP ribose polymerase (PARP) cleavage and DNA fragmentation assay results showed that CEB4 induces apoptosis mediated cell death. Western blotting results demonstrated that the induction of apoptosis by CEB4 appeared to be mediated through regulation of the p53 signalling pathway as there was an increase in p53 phosphorylation levels. CEB4 was also found to up-regulate the pro-apoptotic protein, Bax, while down-regulating the anti-apoptotic protein, Bcl-2, suggesting the involvement of the intrinsic mitochondrial pathway. Reduced levels of initiator procaspase-9 and executioner caspase-3 zymogen were also observed following CEB4 exposure, hence indicating the involvement of cytochrome c mediated apoptosis. These results demonstrate the cytotoxic and apoptotic ability of erythrocarpine E, and suggest its potential development as a cancer chemopreventive agent.
    Matched MeSH terms: Mouth Neoplasms/metabolism
  2. Heterotrimeric G-protein alpha-12 (Gα12) subunit promotes oral cancer metastasis
    Gan CP, Patel V, Mikelis CM, Zain RB, Molinolo AA, Abraham MT, et al.
    Oncotarget, 2014 Oct 30;5(20):9626-40.
    PMID: 25275299
    Oral squamous cell carcinoma (OSCC) has a propensity to spread to the cervical lymph nodes (LN). The presence of cervical LN metastases severely impacts patient survival, whereby the two-year survival for oral cancer patients with involved LN is ~30% compared to over 80% in patients with non-involved LN. Elucidation of key molecular mechanisms underlying OSCC metastasis may afford an opportunity to target specific genes, to prevent the spread of OSCC and to improve patient survival. In this study, we demonstrated that expression of the heterotrimeric G-protein alpha-12 (Gα12) is highly up-regulated in primary tumors and LN of OSCC patients, as assessed by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC). We also found that exogenous expression of the constitutively activated-form of Gα12 promoted cell migration and invasion in OSCC cell lines. Correspondingly, inhibition of Gα12 expression by shRNA consistently inhibited OSCC cell migration and invasion in vitro. Further, the inhibition of G12 signaling by regulator of G-protein signaling (RGS) inhibited Gα12-mediated RhoA activation, which in turn resulted in reduced LN metastases in a tongue-orthotopic xenograft mouse model of oral cancer. This study provides a rationale for future development and evaluation of drug candidates targeting Gα12-related pathways for metastasis prevention.
    Matched MeSH terms: Mouth Neoplasms/metabolism*
  3. Fulltext CD4+CD25hiCD127low regulatory T cells are increased in oral squamous cell carcinoma patients
    Lim KP, Chun NA, Ismail SM, Abraham MT, Yusoff MN, Zain RB, et al.
    PLoS One, 2014;9(8):e103975.
    PMID: 25153698 DOI: 10.1371/journal.pone.0103975
    Regulatory T cells (Tregs), a subset of CD4+ T cells plays a pivotal role in regulating the immune system. An increase in Treg numbers enables cancer progression by dampening the immune system and allowing tumor cells to evade immune detection and destruction. An increase in Treg numbers and expression of inhibitory cytokines including TGF-β and IL-10 are mechanisms by which Tregs exert their immune suppressive function. However, the presence of Tregs and inhibitory cytokines in oral cancer patients is still unclear. In this study, the presence of circulating Tregs in 39 oral cancer patients and 24 healthy donors was examined by studying the presence of the CD4+CD25hiCD127low cell population in their peripheral blood mononuclear cells using flow cytometry. Serum levels of TGF-β and IL-10 were measured by ELISA. T cell subsets of OSCC patients were found to differ significantly from healthy donors where a decrease in CD8+ cytotoxic T cells and an increase in Tregs (CD4+CD25hiCD127low) were observed. Further, the ratio of CD8+ T cells/Tregs was also decreased in patients compared to healthy donors. The presence of Tregs was accompanied by a decrease in IL-10 but not TGF-β secretion in OSCC patients when compared to donors; in addition, the analysis also revealed that an increased presence of Tregs was accompanied by better patient survival. Amongst OSCC patients, smokers had significantly higher levels of TGF-β. It is apparent that the immune system is compromised in OSCC patients and the characterization of the Treg subpopulation could form a basis for improving our understanding of the perturbations in the immune system that occur during OSCC tumorigenesis.
    Matched MeSH terms: Mouth Neoplasms/metabolism
  4. Four-protein signature accurately predicts lymph node metastasis and survival in oral squamous cell carcinoma
    Zanaruddin SN, Saleh A, Yang YH, Hamid S, Mustafa WM, Khairul Bariah AA, et al.
    Hum Pathol, 2013 Mar;44(3):417-26.
    PMID: 23026198 DOI: 10.1016/j.humpath.2012.06.007
    The presence of lymph node (LN) metastasis significantly affects the survival of patients with oral squamous cell carcinoma (OSCC). Successful detection and removal of positive LNs are crucial in the treatment of this disease. Current evaluation methods still have their limitations in detecting the presence of tumor cells in the LNs, where up to a third of clinically diagnosed metastasis-negative (N0) patients actually have metastasis-positive LNs in the neck. We developed a molecular signature in the primary tumor that could predict LN metastasis in OSCC. A total of 211 cores from 55 individuals were included in the study. Eleven proteins were evaluated using immunohistochemical analysis in a tissue microarray. Of the 11 biomarkers evaluated using receiver operating curve analysis, epidermal growth factor receptor (EGFR), v-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (HER-2/neu), laminin, gamma 2 (LAMC2), and ras homolog family member C (RHOC) were found to be significantly associated with the presence of LN metastasis. Unsupervised hierarchical clustering-demonstrated expression patterns of these 4 proteins could be used to differentiate specimens that have positive LN metastasis from those that are negative for LN metastasis. Collectively, EGFR, HER-2/neu, LAMC2, and RHOC have a specificity of 87.5% and a sensitivity of 70%, with a prognostic accuracy of 83.4% for LN metastasis. We also demonstrated that the LN signature could independently predict disease-specific survival (P = .036). The 4-protein LN signature validated in an independent set of samples strongly suggests that it could reliably distinguish patients with LN metastasis from those who were metastasis-free and therefore could be a prognostic tool for the management of patients with OSCC.
    Matched MeSH terms: Mouth Neoplasms/metabolism
  5. Human telomerase reverse transcriptase expression in oral carcinogenesis--a preliminary report
    Kumar SK, Zain RB, Ismail SM, Cheong SC
    J Exp Clin Cancer Res, 2005 Dec;24(4):639-46.
    PMID: 16471328
    Human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase, is strongly associated with telomerase activity implicated in cellular immortalization and tumorigenesis. In situ detection of hTERT will aid in determining the localization of telomerase positive cells. The aim of this study was to detect hTERT protein expression in multistep oral carcinogenesis using paraffin embedded tissue samples, and to study the relationship of hTERT expression with different histological stages in oral carcinogenesis. Normal (n = 4), hyperplastic (n = 4), dysplastic (n = 4) and neoplastic (n = 10) oral epithelia representing different histological stages in oral carcinogenesis were included in the study. hTERT protein detection was done by immunohistochemistry (IHC) technique. Nuclear staining intensities were noted and the hTERT-labelling index was determined. Dysplastic and neoplastic oral epithelia showed an increased percentage of hTERT positive cells (Grade 4: > 50% positive staining nuclei) with intense staining in the basal, parabasal and superficial layers of the epithelia, unlike normal oral mucosa which showed intense staining only in the basal and parabasal cell layers, which are the normal proliferative progenitor compartments. hTERT protein expression was elevated with the corresponding advancement of the histological stages of oral carcinogenesis, from normal to hyperplasia to dysplasia to carcinoma. There seems to be an upregulation of hTERT protein expression during the progression of oral cancer, therefore, this may indicate the feasibility of IHC detection of hTERT protein in oral carcinogenesis as a potential diagnostic or prognostic marker.
    Matched MeSH terms: Mouth Neoplasms/metabolism*
  6. HPV infection and the alterations of the pRB pathway in oral carcinogenesis
    Lim KP, Hamid S, Lau SH, Teo SH, Cheong SC
    Oncol Rep, 2007 Jun;17(6):1321-6.
    PMID: 17487385 DOI: 10.3892/or.17.6.1321
    Inactivation of the retinoblastoma (pRB) pathway is a common event in oral squamous cell carcinoma particularly through the aberrant expression of the components within this pathway. This study examines the alterations of molecules within the pRB pathway by looking at the presence of homozygous deletions in p16(INK4A) and the expression patterns of pRB, cyclin D1 and CDK4, as well as the presence of human papillomavirus (HPV) in our samples. In our study, 5/20 samples demonstrated deletions of p16(INK4A) exon 1alpha. pRB overexpression was found in 20/20 samples, the expression was mainly observed in all layers of the epithelia, particularly in the basal layer where cells are actively dividing and aberrant pRB expression was found in 12/20 samples. Cyclin D1 and CDK4 overexpression was detected in 6/20 and 2/20 samples respectively in comparison to hyperplasias where both proteins were either not expressed or expressed at minimal levels (<10%). Strikingly, HPV was found to be present in all of our samples, suggesting that HPV plays a significant role in driving oral carcinogenesis. Notably, 17/20 of our samples showed more than one alteration in the pRB pathway, however, we did not find any significant relationship between the presence of HPV, homozygous deletion of p16(INK4A) and overexpression of pRB, cyclin D1 and CDK4. Collectively, this data demonstrates that alterations in the pRB pathway are a common event and involve the aberration of more than one molecule within the pathway. Furthermore, the involvement of HPV in all our samples suggests that HPV infection may play an important role in oral carcinogenesis.
    Matched MeSH terms: Mouth Neoplasms/metabolism
  7. Alterations of the p14ARF-p53-MDM2 pathway in oral squamous cell carcinoma: MDM2 overexpression is a common event
    Lim KP, Sharifah H, Lau SH, Teo SH, Cheong SC
    Oncol Rep, 2005 Oct;14(4):963-8.
    PMID: 16142358 DOI: 10.3892/or.14.4.963
    The majority of global incidences of oral cancer occur in Asia, and the aetiology of oral cancer is different in Asia as it is in the West. However, whereas there is a growing understanding of the molecular mechanisms of oral cancer progression in the West, there is little progress in this understanding in Asia. In particular, the role of the p53 pathway in modulating cancer progression in Asian oral cancer remains unclear. In this study, we micro-dissected and analysed 20 well-differentiated oral squamous cell carcinoma specimens for alterations in the p53 pathway. We found that 6/20 samples contained mutations in the p53 gene which occurred in three hotspots, at codon 203, 218 and 296. Furthermore, 6/20 samples had a homozygous deletion of p14ARF, but notably p14ARF deletion and p53 mutation events were often independent and mutually exclusive. Strikingly, MDM2 was upregulated in 20/20 samples, but not in 3/3 normal tissue specimens. Taken together, these data suggest that inactivation of the p53 pathway is a frequent event in oral squamous cell carcinoma, which occurs by an aberration in one of a number of players in the p53 pathway.
    Matched MeSH terms: Mouth Neoplasms/metabolism*
  8. Translational genomics and recent advances in oral squamous cell carcinoma
    Chai AWY, Lim KP, Cheong SC
    Semin Cancer Biol, 2020 04;61:71-83.
    PMID: 31542510 DOI: 10.1016/j.semcancer.2019.09.011
    Oral squamous cell carcinomas (OSCC) are a heterogeneous group of cancers arising from the mucosal lining of the oral cavity. A majority of these cancers are associated with lifestyle risk habits including smoking, excessive alcohol consumption and betel quid chewing. Cetuximab, targeting the epidermal growth factor receptor was approved for the treatment of OSCC in 2006, and remains the only molecular targeted therapy available for OSCC. Here, we reviewed the current findings from genomic analyses of OSCC and discuss how these studies inform on the biological mechanisms underlying OSCC. Exome sequencing revealed that the significantly mutated genes are mainly tumour suppressors. Mutations in FAT1, CASP8, CDKN2A, and NOTCH1 are more frequently found in OSCC when compared to non-OSCC head and neck cancers and other squamous cell carcinomas, and HRAS and PIK3CA are the only significantly mutated oncogenes. The distribution of these mutations also differs in populations with distinct risk habits. Gene expression-based molecular classification showed that OSCC can be divided into distinct subtypes and these have a preferential response to different types of therapies, suggesting that these classifications could have clinical implications. More recently, with the approval of checkpoint inhibitors for the treatment of cancers including OSCC, genomics studies also dissected the genetic signatures of the immune compartment to delineate immune-active and -exhausted subtypes that could inform on the immune status of OSCC patients and guide the development of novel therapies to improve response to immunotherapy. Taken together, genomics studies are informing on the biology of both the epithelial and stromal compartments underlying OSCC development, and we discuss the opportunities and challenges in using these to derive clinical benefit for OSCC patients.
    Matched MeSH terms: Mouth Neoplasms/metabolism
  9. Synergistic Growth Inhibition by Afatinib and Trametinib in Preclinical Oral Squamous Cell Carcinoma Models
    Yee PS, Zainal NS, Gan CP, Lee BKB, Mun KS, Abraham MT, et al.
    Target Oncol, 2019 04;14(2):223-235.
    PMID: 30806895 DOI: 10.1007/s11523-019-00626-8
    BACKGROUND: Given that aberrant activation of epidermal growth factor receptor family receptors (ErbB) is a common event in oral squamous cell carcinoma, and that high expression of these receptor proteins is often associated with poor prognosis, this rationalizes the approach of targeting ErbB signaling pathways to improve the survival of patients with oral squamous cell carcinoma. However, monotherapy with the ErbB blocker afatinib has shown limited survival benefits.

    OBJECTIVES: This study was performed to identify mechanisms of afatinib resistance and to explore potential afatinib-based combination treatments with other targeted inhibitors in oral squamous cell carcinoma.

    METHODS: We determined the anti-proliferative effects of afatinib on a panel of oral squamous cell carcinoma cell lines using a crystal violet-growth inhibition assay, click-iT 5-ethynyl-2'-deoxyuridine staining, and cell-cycle analysis. Biochemical assays were performed to study the underlying mechanism of drug treatment as a single agent or in combination with the MEK inhibitor trametinib. We further evaluated and compared the anti-tumor effects of single agent and combined treatment by using oral squamous cell carcinoma xenograft models.

    RESULTS: In this study, we showed that afatinib inhibited oral squamous cell carcinoma cell proliferation via cell-cycle arrest at the G0/G1 phase, and inhibited tumor growth in xenograft mouse models. Interestingly, we demonstrated reactivation of the mitogen-activated protein kinase (ERK1/2) pathway in vitro, which possibly reduced the effects of ErbB inhibition. Concomitant treatment of oral squamous cell carcinoma cells with afatinib and trametinib synergized the anti-tumor effects in oral squamous cell carcinoma-bearing mouse models.

    CONCLUSIONS: Our findings provide insight into the molecular mechanism of resistance to afatinib and support further clinical evaluation into the combination of afatinib and MEK inhibition in the treatment of oral squamous cell carcinoma.

    Matched MeSH terms: Mouth Neoplasms/metabolism
  10. Over-expression of MAGED4B increases cell migration and growth in oral squamous cell carcinoma and is associated with poor disease outcome
    Chong CE, Lim KP, Gan CP, Marsh CA, Zain RB, Abraham MT, et al.
    Cancer Lett, 2012 Aug 1;321(1):18-26.
    PMID: 22459352 DOI: 10.1016/j.canlet.2012.03.025
    MAGE proteins have been shown to be good targets for cancer immunotherapy. We demonstrate that MAGED4B is over-expressed in more than 50% of Oral Squamous Cell Carcinoma (OSCC) tissues and the expression of MAGED4B is associated with lymph node metastasis and poor disease specific survival. OSCC cell lines that over-express MAGED4B promote migration in vitro, exhibit an increase in cell growth both in vitro and in vivo, and are more resistant to apoptosis compared to control cells. Our data suggest that MAGED4B over-expression is a driver in oral carcinogenesis and argues strongly that this protein may represent a potential therapeutic target in OSCC.
    Matched MeSH terms: Mouth Neoplasms/metabolism*
  11. Zerumbone targets the CXCR4-RhoA and PI3K-mTOR signaling axis to reduce motility and proliferation of oral cancer cells
    Zainal NS, Gan CP, Lau BF, Yee PS, Tiong KH, Abdul Rahman ZA, et al.
    Phytomedicine, 2018 Jan 15;39:33-41.
    PMID: 29433681 DOI: 10.1016/j.phymed.2017.12.011
    BACKGROUND: The CXCR4-RhoA and PI3K-mTOR signaling pathways play crucial roles in the dissemination and tumorigenesis of oral squamous cell carcinoma (OSCC). Activation of these pathways have made them promising molecular targets in the treatment of OSCC. Zerumbone, a bioactive monocyclic sesquiterpene isolated from the rhizomes of tropical ginger, Zingiber zerumbet (L.) Roscoe ex Sm. has displayed promising anticancer properties with the ability to modulate multiple molecular targets involved in carcinogenesis. While the anticancer activities of zerumbone have been well explored across different types of cancer, the molecular mechanism of action of zerumbone in OSCC remains largely unknown.

    PURPOSE: Here, we investigated whether OSCC cells were sensitive towards zerumbone treatment and further determined the molecular pathways involved in the mechanism of action.

    METHODS: Cytotoxicity, anti-proliferative, anti-migratory and anti-invasive effects of zerumbone were tested on a panel of OSCC cell lines. The mechanism of action of zerumbone was investigated by analysing the effects on the CXCR4-RhoA and PI3K-mTOR pathways by western blotting.

    RESULTS: Our panel of OSCC cells was broadly sensitive towards zerumbone with IC50 values of less than 5 µM whereas normal keratinocyte cells were less responsive with IC50 values of more than 25 µM. Representative OSCC cells revealed that zerumbone inhibited OSCC proliferation and induced cell cycle arrest and apoptosis. In addition, zerumbone treatment inhibited migration and invasion of OSCC cells, with concurrent suppression of endogenous CXCR4 protein expression in a time and dose-dependent manner. RhoA-pull down assay showed reduction in the expression of RhoA-GTP, suggesting the inactivation of RhoA by zerumbone. In association with this, zerumbone also inhibited the PI3K-mTOR pathway through the inactivation of Akt and S6 proteins.

    CONCLUSION: We provide evidence that zerumbone could inhibit the activation of CXCR4-RhoA and PI3K-mTOR signaling pathways leading to the reduced cell viability of OSCC cells. Our results suggest that zerumbone is a promising phytoagent for development of new therapeutics for OSCC treatment.

    Matched MeSH terms: Mouth Neoplasms/metabolism
  12. Fulltext IFITM3 knockdown reduces the expression of CCND1 and CDK4 and suppresses the growth of oral squamous cell carcinoma cells
    Gan CP, Sam KK, Yee PS, Zainal NS, Lee BKB, Abdul Rahman ZA, et al.
    Cell Oncol (Dordr), 2019 Aug;42(4):477-490.
    PMID: 30949979 DOI: 10.1007/s13402-019-00437-z
    PURPOSE: Oral squamous cell carcinoma (OSCC) is a challenging disease to treat. Up to 50% of OSCC patients with advanced disease develop recurrences. Elucidation of key molecular mechanisms underlying OSCC development may provide opportunities to target specific genes and, thus, to improve patient survival. In this study, we examined the expression and functional role of interferon transmembrane protein 3 (IFITM3) in OSCC development.

    METHODS: The expression of IFITM3 in OSCC and normal oral mucosal tissues was assessed by qRT-PCR and immunohistochemistry. The role of IFITM3 in driving OSCC cell proliferation and survival was examined using siRNA-mediated gene knockdown, and the role of IFITM3 in driving cell cycle regulators was examined using Western blotting.

    RESULTS: We found that IFITM3 is overexpressed in more than 79% of primary OSCCs. We also found that IFITM3 knockdown led to impaired OSCC cell growth through inhibition of cell proliferation, induction of cell cycle arrest, senescence and apoptosis. In addition, we found that IFITM3 knockdown led to reduced expressions of CCND1 and CDK4 and reduced RB phosphorylation, leading to inhibition of OSCC cell growth. This information may be instrumental for the design of novel targeted therapeutic strategies.

    CONCLUSIONS: From our data we conclude that IFITM3 is overexpressed in OSCC and may regulate the CCND1-CDK4/6-pRB axis to mediate OSCC cell growth.

    Matched MeSH terms: Mouth Neoplasms/metabolism*
  13. Fulltext Mitochondrial DNA alterations may influence the cisplatin responsiveness of oral squamous cell carcinoma
    Aminuddin A, Ng PY, Leong CO, Chua EW
    Sci Rep, 2020 May 12;10(1):7885.
    PMID: 32398775 DOI: 10.1038/s41598-020-64664-3
    Cisplatin is the first-line chemotherapeutic agent for the treatment of oral squamous cell carcinoma (OSCC). However, the intrinsic or acquired resistance against cisplatin remains a major obstacle to treatment efficacy in OSCC. Recently, mitochondrial DNA (mtDNA) alterations have been reported in a variety of cancers. However, the role of mtDNA alterations in OSCC has not been comprehensively studied. In this study, we evaluated the correlation between mtDNA alterations (mtDNA content, point mutations, large-scale deletions, and methylation status) and cisplatin sensitivity using two OSCC cell lines, namely SAS and H103, and stem cell-like tumour spheres derived from SAS. By microarray analysis, we found that the tumour spheres profited from aberrant lipid and glucose metabolism and became resistant to cisplatin. By qPCR analysis, we found that the cells with less mtDNA were less responsive to cisplatin (H103 and the tumour spheres). Based on the findings, we theorised that the metabolic changes in the tumour spheres probably resulted in mtDNA depletion, as the cells suppressed mitochondrial respiration and switched to an alternative mode of energy production, i.e. glycolysis. Then, to ascertain the origin of the variation in mtDNA content, we used MinION, a nanopore sequencer, to sequence the mitochondrial genomes of H103, SAS, and the tumour spheres. We found that the lower cisplatin sensitivity of H103 could have been caused by a constellation of genetic and epigenetic changes in its mitochondrial genome. Future work may look into how changes in mtDNA translate into an impact on cell function and therefore cisplatin response.
    Matched MeSH terms: Mouth Neoplasms/metabolism
  14. Aberrant proteins in the saliva of patients with oral squamous cell carcinoma
    Jessie K, Jayapalan JJ, Ong KC, Abdul Rahim ZH, Zain RM, Wong KT, et al.
    Electrophoresis, 2013 Sep;34(17):2495-502.
    PMID: 23784731 DOI: 10.1002/elps.201300107
    Confirmation of oral squamous cell cancer (OSCC) currently relies on histological analysis, which does not provide clear indication of cancer development from precancerous lesions. In the present study, whole saliva proteins of patients with OSCC (n = 12) and healthy subjects (n = 12) were separated by 2DE to identify potential candidate biomarkers that are much needed to improve detection of the cancer. The OSCC patients' 2DE saliva protein profiles appeared unique and different from those obtained from the healthy subjects. The patients' saliva α1-antitrypsin (AAT) and haptoglobin (HAP) β chains were resolved into polypeptide spots with increased microheterogeneity, although these were not apparent in their sera. Their 2DE protein profiles also showed presence of hemopexin and α-1B glycoprotein, which were not detected in the profiles of the control saliva. When subjected to densitometry analysis, significant altered levels of AAT, complement C3, transferrin, transthyretin, and β chains of fibrinogen and HAP were detected. The increased levels of saliva AAT, HAP, complement C3, hemopexin, and transthyretin in the OSCC patients were validated by ELISA. The strong association of AAT and HAP with OSCC was further supported by immunohistochemical staining of cancer tissues. The differently expressed saliva proteins may be useful complementary biomarkers for the early detection and/or monitoring of OSCC, although this requires validation in clinically representative populations.
    Matched MeSH terms: Mouth Neoplasms/metabolism*
  15. A new naturally derived photosensitizer and its phototoxicity on head and neck cancer cells
    Lim SH, Lee HB, Ho AS
    Photochem Photobiol, 2011 Sep-Oct;87(5):1152-8.
    PMID: 21534974 DOI: 10.1111/j.1751-1097.2011.00939.x
    In our screening for photosensitizers from natural resources, 15(1)-hydroxypurpurin-7-lactone ethyl methyl diester (compound 1) was isolated for the first time from an Araceae plant. To evaluate the efficacy of compound 1 as a photosensitizer for head and neck cancers, compound 1 was studied in reference to a known photosensitizer pheophorbide-a (Pha), in terms of photophysical properties, singlet oxygen generation and in in vitro experiments (intracellular uptake and phototoxicity assays) in two oral (HSC2 and HSC3) and two nasopharyngeal (HK1 and C666-1) cancer cell lines. In this study, compound 1 exhibited higher intracellular uptake over 24 h compared with Pha in both HSC3 and HK1 cells. When activated by ≥4.8 J cm(-2) of light, compound 1 was slightly more potent as a photosensitizer than Pha by consistently having marginally lower IC(50) values across different cell lines. In flow cytometry experiments to study the mechanism of photoactivated cell death in HSC3, compound 1 was observed to induce more pronounced apoptosis compared with Pha, which may have been driven by the transient G(2)/M cell cycle block which was also observed. These promising results on compound 1 warrant its further investigation as a clinically useful photodynamic therapy agent for head and neck cancer.
    Matched MeSH terms: Mouth Neoplasms/metabolism
  16. p53 Expression as a marker of microinvasion in oral squamous cell carcinoma
    Heah KG, Hassan MI, Huat SC
    Asian Pac J Cancer Prev, 2011;12(4):1017-22.
    PMID: 21790244
    INTRODUCTION: Oral squamous cell carcinoma (OSCC) has high local recurrence, partly caused by the lack of clear margin identification on surgical removal of cancerous tissues. Direct visualization by immunostaining and fluorescent in situ hybridization (FISH) in tissue sections gives more definite information about genetic damage at margins with appropriately selected biomarkers.

    AIMS: To determine the usefulness of immunohistochemical techniques and FISH of the tumour suppressor TP 53 gene to identify microinvasion in marginal tissue sections and to relate the possible correlation between protein expression and genetic aberrations in OSCC cases in Malaysia.

    METHODS: Immunohistochemistry and FISH of TP 53 genes were applied on 26 OSCC formalin fixed paraffin embed (FFEP) blocks selected from two oral cancer referral centers in Malaysia.

    RESULTS: For p53 protein immunohistochemistry, 96% of the 26 OSCC studied showed positive immunostaining at the excision margins. In FISH assay, 48.9±9.7% of the cancerous cells were monoploid for p53 probe signals, 41.0±9.5 % were diploid, and 10.2±7.8 % were polyploid. A correlation between p53 immunostaining and TP53 gene aberrations was noted (p< 0.05).

    CONCLUSIONS: Immunohistochemical analysis of p53 protein expression and FISH of TP53 gene could be applied as screening tool for microinvasion of OSCC.

    Matched MeSH terms: Mouth Neoplasms/metabolism
  17. Correlation of Arsenic Levels in Smokeless Tobacco Products and Biological Samples of Oral Cancer Patients and Control Consumers
    Arain SS, Kazi TG, Afridi HI, Talpur FN, Kazi AG, Brahman KD, et al.
    Biol Trace Elem Res, 2015 Dec;168(2):287-95.
    PMID: 25975948 DOI: 10.1007/s12011-015-0355-y
    It has been extensively reported that chewing of smokeless tobacco (SLT) can lead to cancers of oral cavity. In present study, the relationship between arsenic (As) exposure via chewing/inhaling different SLT products in oral cancer patients have or/not consumed SLT products was studied. The As in different types of SLT products (gutkha, mainpuri, and snuff) and biological (scalp hair and blood) samples of different types of oral cancer patients and controls were analyzed. Both controls and oral cancer patients have same age group (ranged 30-60 years), socio-economic status, localities, and dietary habits. The concentrations of As in SLT products and biological samples were measured by electrothermal atomic absorption spectrophotometer after microwave-assisted acid digestion. The validity and accuracy of the methodology were checked by certified reference materials. The resulted data of present study indicates that the concentration of As was significantly higher in scalp hair and blood samples of oral cancer patients than those of controls (p<0.001). It was also observed that the values of As were two- to threefolds higher in biological samples of controls subjects, consuming SLT products as compared to those have none of these habits (p>0.01). The intake of As via consuming different SLT may have synergistic effects, in addition to other risk factors associated with oral cancer.
    Matched MeSH terms: Mouth Neoplasms/metabolism*
  18. Oral cancer secretome: identification of cancer-associated proteins
    Chang HY, Hor SY, Lim KP, Zain RB, Cheong SC, Rahman MA, et al.
    Electrophoresis, 2013 Aug;34(15):2199-208.
    PMID: 23712713 DOI: 10.1002/elps.201300126
    This study aims to identify cancer-associated proteins in the secretome of oral cancer cell lines. We have successfully established four primary cell cultures of normal cells with a limited lifespan without human telomerase reverse transcriptase (hTERT) immortalization. The secretome of these primary cell cultures were compared with that of oral cancer cell lines using 2DE. Thirty five protein spots were found to have changed in abundance. Unambiguous identification of these proteins was achieved by MALDI TOF/TOF. In silico analysis predicted that 24 of these proteins were secreted via classical or nonclassical mechanisms. The mRNA expression of six genes was found to correlate with the corresponding protein abundance. Ingenuity Pathway Analysis (IPA) core analysis revealed that the identified proteins were relevant in, and related to, cancer development with likely involvements in tumor growth, metastasis, hyperproliferation, tumorigenesis, neoplasia, hyperplasia, and cell transformation. In conclusion, we have demonstrated that a comparative study of the secretome of cancer versus normal cell lines can be used to identify cancer-associated proteins.
    Matched MeSH terms: Mouth Neoplasms/metabolism
  19. A miRNA-145/TGF-β1 negative feedback loop regulates the cancer-associated fibroblast phenotype
    Melling GE, Flannery SE, Abidin SA, Clemmens H, Prajapati P, Hinsley EE, et al.
    Carcinogenesis, 2018 05 28;39(6):798-807.
    PMID: 29506142 DOI: 10.1093/carcin/bgy032
    The dissemination of cancer cells to local and distant sites depends on a complex and poorly understood interplay between malignant cells and the cellular and non-cellular components surrounding them, collectively termed the tumour microenvironment. One of the most abundant cell types of the tumour microenvironment is the fibroblast, which becomes corrupted by locally derived cues such as TGF-β1 and acquires an altered, heterogeneous phenotype (cancer-associated fibroblasts, CAF) supportive of tumour cell invasion and metastasis. Efforts to develop new treatments targeting the tumour mesenchyme are hampered by a poor understanding of the mechanisms underlying the development of CAF. Here, we examine the contribution of microRNA to the development of experimentally-derived CAF and correlate this with changes observed in CAF derived from tumours. Exposure of primary normal human fibroblasts to TGF-β1 resulted in the acquisition of a myofibroblastic CAF-like phenotype. This was associated with increased expression of miR-145, a miRNA predicted in silico to target multiple components of the TGF-β signalling pathway. miR-145 was also overexpressed in CAF derived from oral cancers. Overexpression of miR-145 blocked TGF-β1-induced myofibroblastic differentiation and reverted CAF towards a normal fibroblast phenotype. We conclude that miR-145 is a key regulator of the CAF phenotype, acting in a negative feedback loop to dampen acquisition of myofibroblastic traits, a key feature of CAF associated with poor disease outcome.
    Matched MeSH terms: Mouth Neoplasms/metabolism*
  20. Copper supplementation amplifies the anti-tumor effect of curcumin in oral cancer cells
    Lee HM, Patel V, Shyur LF, Lee WL
    Phytomedicine, 2016 Nov 15;23(12):1535-1544.
    PMID: 27765374 DOI: 10.1016/j.phymed.2016.09.005
    BACKGROUND: Oral cancer is the sixth most common cancer worldwide and 90% of oral malignancies are caused by oral squamous cell carcinoma (OSCC). Curcumin, a phytocompound derived from turmeric (Curcuma longa) was observed to have anti-cancer activity which can be developed as an alternative treatment option for OSCC. However, OSCC cells with various clinical-pathological features respond differentially to curcumin treatment.

    HYPOTHESIS: Intracellular copper levels have been reported to correlate with tumor pathogenesis and affect the sensitivity of cancer cells to cytotoxic chemotherapy. We hypothesized that intracellular copper levels may affect the sensitivity of oral cancer cells to curcumin.

    METHODS: We analysed the correlation between intracellular copper levels and response to curcumin treatment in a panel of OSCC cell lines derived from oral cancer patients. Exogenous copper was supplemented in curcumin insensitive cell lines to observe the effect of copper on curcumin-mediated inhibition of cell viability and migration, as well as induction of oxidative stress and apoptosis. Protein markers of cell migration and oxidative stress were also analysed using Western blotting.

    RESULTS: Concentrations of curcumin which inhibited 50% OSCC cell viability (IC50) was reduced up to 5 times in the presence of 250 µM copper. Increased copper level in curcumin-treated OSCC cells was accompanied by the induction of intracellular ROS and increased level of Nrf2 which regulates oxidative stress responses in cells. Supplemental copper also inhibited migration of curcumin-treated cells with enhanced level of E-cadherin and decreased vimentin, indications of suppressed epithelial-mesenchymal transition. Early apoptosis was observed in combined treatment but not in treatment with curcumin or copper alone.

    CONCLUSION: Supplement of copper significantly enhanced the inhibitory effect of curcumin treatment on migration and viability of oral cancer cells. Together, these findings provide molecular insight into the role of copper in overcoming insensitivity of oral cancer cells to curcumin treatment, suggesting a new strategy for cancer therapy.

    Matched MeSH terms: Mouth Neoplasms/metabolism
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