Comparative sera proteomics analysis of differentially expressed proteins in oral squamous cell carcinoma.

BACKGROUND: Oral squamous cell carcinoma (OSCC) has increased in incidence from 1990 to 2017, especially in South and Southeast Asia. It is often diagnosed at an advanced stage with a poor prognosis. Therefore, early detection of OSCC is essential to improve the prognosis of OSCC. This study aims to identify the differentially expressed serum proteins as potential biomarkers for oral squamous cell carcinoma (OSCC). METHODS: Comparative proteomics profiling of serum samples from OSCC patients, oral potentially malignant disorder (OPMD) patients, and healthy individuals were performed using two-dimensional gel electrophoresis (2-DE) coupled with mass spectrometry (MS) (n = 60) and bioinformatics analysis. The enzyme-linked immunosorbent assay (ELISA) (n = 120) and immunohistochemistry (IHC) (n = 70) were used to confirm our findings. RESULTS: The 2-DE analysis revealed that 20 differentially expressed proteins were detected in OPMD and OSCC (p < 0.05). Bioinformatics analysis indicated that the activation of classical complement, liver X receptor/retinoid X receptor (LXR/RXR) activation, and acute phase response signaling pathway are associated with the development and progression of OSCC. Most of the detected proteins are acute-phase proteins and were related to inflammation and immune responses, including apolipoprotein A-I (APOA1), complement C3 (C3), clusterin (CLU), and haptoglobin (HP). The expression levels of CLU and HP in ELISA are consistent with the findings from the 2-DE analysis, except for the mean serum level of HP in OPMD, whereby it was slightly higher than that in control. IHC results demonstrated that CLU and HP are significantly decreased in OSCC tissues. CONCLUSION: Decreased expression of CLU and HP could serve as complementary biomarkers of OSCC. These proteins may assist in predicting the outcomes of OSCC patients. However, a larger cohort is needed for further investigation.

Identification of potential glycoprotein biomarkers in oral squamous cell carcinoma using sweet strategies.

The prevalence of oral squamous cell carcinoma (OSCC) is high in South and Southeast Asia regions. Most OSCC patients are detected at advanced stages low 5-year survival rates. Aberrant expression of glycosylated proteins was found to be associated with malignant transformation and cancer progression. Hence, identification of cancer-associated glycoproteins could be used as potential biomarkers that are beneficial for diagnosis or clinical management of patients. This study aims to identify the differentially expressed glycoproteins using lectin-based glycoproteomics approaches. Serum samples of 40 patients with OSCC, 10 patients with oral potentially malignant disorder (OPMD), and 10 healthy individuals as control group were subjected to two-dimensional gel electrophoresis (2-DE) coupled with lectin Concanavalin A and Jacalin that specifically bind to N- and O-glycosylated proteins, respectively. Five differentially expressed N- and O-glycoproteins with various potential glycosylation sites were identified, namely N-glycosylated α1-antitrypsin (AAT), α2-HS-glycoprotein (AHSG), apolipoprotein A-I (APOA1), and haptoglobin (HP); as well as O-glycosylated AHSG and clusterin (CLU). Among them, AAT and APOA1 were further validated using enzyme-linked immunosorbent assay (ELISA) (n = 120). It was found that AAT and APOA1 are significantly upregulated in OSCC and these glycoproteins are independent risk factors of OSCC. The clinical utility of AAT and APOA1 as potential biomarkers of OSCC is needed for further evaluation.

Survival of Oral Cancer Patients in Different Ethnicities.

Previous studies found that ethnicity influences oral cancer patients' survival; however, most studies were limited to certain ethnic groups particularly from the West, thus of limited relevance to Asians where the disease is most prevalent. We investigated the relationship between ethnicity and patient survival in multi-racial Malaysia. 5-year survival rate was 40.9%. No statistically significant difference was observed in survival between Malays, Chinese, Indians and Indigenous peoples (45.7%, 44.0%, 41.3%, 27.7% respectively). Increased tumor size, lymph node involvement and advanced tumor were predictive of poor survival. We conclude that ethnicity has no effect on survival or its prognostic indicators.

Genetically-defined novel oral squamous cell carcinoma cell lines for the development of molecular therapies.

Emerging biological and translational insights from large sequencing efforts underscore the need for genetically-relevant cell lines to study the relationships between genomic alterations of tumors, and therapeutic dependencies. Here, we report a detailed characterization of a novel panel of clinically annotated oral squamous cell carcinoma (OSCC) cell lines, derived from patients with diverse ethnicity and risk habits. Molecular analysis by RNAseq and copy number alterations (CNA) identified that the cell lines harbour CNA that have been previously reported in OSCC, for example focal amplications in 3q, 7p, 8q, 11q, 20q and deletions in 3p, 5q, 8p, 18q. Similarly, our analysis identified the same cohort of frequently mutated genes previously reported in OSCC including TP53, CDKN2A, EPHA2, FAT1, NOTCH1, CASP8 and PIK3CA. Notably, we identified mutations (MLL4, USP9X, ARID2) in cell lines derived from betel quid users that may be associated with this specific risk factor. Gene expression profiles of the ORL lines also aligned with those reported for OSCC. By focusing on those gene expression signatures that are predictive of chemotherapeutic response, we observed that the ORL lines broadly clustered into three groups (cell cycle, xenobiotic metabolism, others). The ORL lines noted to be enriched in cell cycle genes responded preferentially to the CDK1 inhibitor RO3306, by MTT cell viability assay. Overall, our in-depth characterization of clinically annotated ORL lines provides new insight into the molecular alterations synonymous with OSCC, which can facilitate in the identification of biomarkers that can be used to guide diagnosis, prognosis, and treatment of OSCC.

Collagen Triple Helix Repeat Containing-1 (CTHRC1) Expression in Oral Squamous Cell Carcinoma (OSCC): Prognostic Value and Clinico-Pathological Implications.

BACKGROUND: Collagen Triple Helix Repeat Containing 1 (CTHRC1) is a protein often found to be over-expressed in various types of human cancers. However, correlation between CTHRC1 expression level with clinico-pathological characteristics and prognosis in oral cancer remains unclear. Therefore, this study aimed to determine mRNA and protein expression of CTHRC1 in oral squamous cell carcinoma (OSCC) and to evaluate the clinical and prognostic impact of CTHRC1 in OSCC. METHODS: In this study, mRNA and protein expression of CTHRC1 in OSCCs were determined by quantitative PCR and immunohistochemistry, respectively. The association between CTHRC1 and clinico-pathological parameters were evaluated by univariate and multivariate binary logistic regression analyses. Correlation between CTHRC1 protein expressions with survival were analysed using Kaplan-Meier and Cox regression models. RESULTS: Current study demonstrated CTHRC1 was significantly overexpressed at the mRNA level in OSCC. Univariate analyses indicated a high-expression of CTHRC1 that was significantly associated with advanced stage pTNM staging, tumour size ≥ 4 cm and positive lymph node metastasis (LNM). However, only positive LNM remained significant after adjusting with other confounder factors in multivariate logistic regression analyses. Kaplan-Meier survival analyses and Cox model demonstrated that patients with high-expression of CTHRC1 protein were associated with poor prognosis and is an independent prognostic factor in OSCC. CONCLUSION: This study indicated that over-expression of CTHRC1 potentially as an independent predictor for positive LNM and poor prognosis in OSCC.

Downregulation of CRNN gene and genomic instability at 1q21.3 in oral squamous cell carcinoma.

OBJECTIVES: This study includes the direct sequencing of cornulin (CRNN) gene to elucidate the possible mechanism of CRNN downregulation and explore the genetic imbalances at 1q21.3 across oral squamous cell carcinoma (OSCC) samples. MATERIALS AND METHODS: In mutation screening of CRNN gene, gDNA from OSCC tissues were extracted, amplified, and followed by direct sequencing. OSCC samples were also subjected to fragment analysis on CRNN gene to investigate its microsatellite instability (MSI) and loss of heterozygosity (LOH). Immunohistochemistry was performed to validate CRNN downregulation in OSCC samples. RESULTS: No pathogenic mutation was found in CRNN gene, while high frequency of allelic imbalances was found at 1q21.3 region. MSI was found more frequent (25.3 %) than LOH (9.3 %). Approximately 22.6 % of cases had high MSI which reflects higher probability of inactivation of DNA mismatch repair genes. MSI showed significant association with no betel quid chewing (p = 0.003) and tongue subsite (p = 0.026). LOH was associated with ethnicity (p = 0.008) and advanced staging (p = 0.039). The LOH at 1q21.3 was identified to be as an independent prognostic marker in OSCC (HRR = 7.15 (95 % CI, 1.41-36.25), p = 0.018). Downregulation of CRNN was found among MSI-positive OSCCs and was associated with poor prognosis (p = 0.044). CONCLUSION: This study showed a significant correlation between LOH/MSI at 1q21.3 with clinical outcomes and that downregulation of CRNN gene could be considered as a prognostic marker of OSCC. CLINICAL RELEVANCE: Insights of the downregulation mode of CRNN gene lays the basis of drug development on this gene as well as revealing its prognostic value.

KRT13, FAIM2 and CYP2W1 mRNA expression in oral squamous cell carcinoma patients with risk habits.

BACKGROUND: Expression of KRT13, FAIM2 and CYP2W1 appears to be influenced by risk habits, thus exploring the associations of these genes in oral squamous cell cancer (OSCC) with risk habits, clinico-pathological parameters and patient survival may be beneficial in identifying relevant biomarkers with different oncogenic pathways. MATERIALS AND METHODS: cDNAs from 41 OSCC samples with and without risk habits were included in this study. Quantitative real-time PCR was used to analyze KRT13, FAIM2 and CYP2W1 in OSCC. The housekeeping gene (GAPDH) was used as an endogenous control. RESULTS: Of the 41 OSCC samples, KRT13 was down-regulated in 40 samples (97.6%), while FAIM2 and CYP2W1 were down-regulated in 61.0% and 48.8%, respectively. Overall, there were no associations between KRT13, FAIM2 and CYP2W1 expression with risk habits, selected socio-demographic and clinico-pathological parameters and patient survival. CONCLUSIONS: Although this study was unable to show significance, there were some tendencies in the associations of KRT13, FAIM2 and CYP2W1 expression in OSCC with selected clinic-pathological parameters and survival.

Overexpression of MMP13 is associated with clinical outcomes and poor prognosis in oral squamous cell carcinoma.

Matrix metalloproteinase 13 (MMP13) plays a central role in the MMP activation cascade that enables degradation of the extracellular matrix and basement membranes, and it is identified as a potential driver in oral carcinogenesis. Therefore, this study aims to determine the copy number, mRNA, and protein expression of MMP13 in oral squamous cell carcinoma (OSCC) and to associate these expressions with clinicopathological parameters. Copy number, mRNA, and protein expression analysis of MMP13 were determined using real-time quantitative PCR and immunohistochemistry methods in OSCC samples. The correlations between MMP13 expressions and clinicopathological parameters were evaluated, and the significance of MMP13 as a prognostic factor was determined. Despite discrepancies between gene amplification and mRNA and protein overexpression rates, OSCC cases showed high amplification of MMP13 and overexpression of MMP13 at both mRNA and protein levels. High level of MMP13 protein expression showed a significant correlation with lymph node metastasis (P = 0.011) and tumor staging (P = 0.002). Multivariate Cox regression model analysis revealed that high level of mRNA and protein expression of MMP13 were significantly associated with poor prognosis (P < 0.050). Taken together, these observations indicate that the MMP13 protein overexpression could be considered as a prognostic marker of OSCC.

High serum level of retinol and α-tocopherol affords protection against oral cancer in a multiethnic population.

BACKGROUND: A comparative cross-sectional study involving oral cancer patients and healthy individuals was designed to investigate associations between retinol, α-tocopherol and ß-carotene with the risk of oral cancer. MATERIALS AND METHODS: This study included a total of 240 matched cases and controls where subjects were selected from the Malaysian Oral Cancer Database and Tissue Bank System (MOCDTBS). Retinol, α-tocopherol and ß-carotene levels and intake were examined by high-performance liquid chromatography (HPLC) and food frequency questionnaire (FFQ) respectively. RESULTS: It was found that results from the two methods applied did not correlate, so that further analysis was done using the HPLC method utilising blood serum. Serum levels of retinol and α-tocopherol among cases (0.177±0.081, 1.649±1.670µg/ml) were significantly lower than in controls (0.264±0.137, 3.225±2.054µg/ml) (p<0.005). Although serum level of ß-carotene among cases (0.106±0.159 µg/ml) were lower compared to controls (0.134±0.131µg/ml), statistical significance was not observed. Logistic regression analysis showed that high serum level of retinol (OR=0.501, 95% CI=0.254-0.992, p<0.05) and α-tocopherol (OR=0.184, 95% CI=0.091-0.370, p<0.05) was significantly related to lower risk of oral cancer, whereas no relationship was observed between ß-carotene and oral cancer risk. CONCLUSIONS: High serum levels of retinol and α-tocopherol confer protection against oral cancer risk.

Genetic alterations of chromosome 8 genes in oral cancer.

The clinical relevance of DNA copy number alterations in chromosome 8 were investigated in oral cancers. The copy numbers of 30 selected genes in 33 OSCC patients were detected using the multiplex ligation-dependent probe amplification (MLPA) technique. Amplifications of the EIF3E gene were found in 27.3% of the patients, MYC in 18.2%, RECQL4 in 15.2% and MYBL1 in 12.1% of patients. The most frequent gene losses found were the GATA4 gene (24.2%), FGFR1 gene (24.2%), MSRA (21.2) and CSGALNACT1 (12.1%). The co-amplification of EIF3E and RECQL4 was found in 9% of patients and showed significant association with alcohol drinkers. There was a significant association between the amplification of EIF3E gene with non-betel quid chewers and the negative lymph node status. EIF3E amplifications did not show prognostic significance on survival. Our results suggest that EIF3E may have a role in the carcinogenesis of OSCC in non-betel quid chewers.

Common oncogenic mutations are infrequent in oral squamous cell carcinoma of Asian origin.

OBJECTIVES: The frequency of common oncogenic mutations and TP53 was determined in Asian oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: The OncoCarta(™) panel v1.0 assay was used to characterize oncogenic mutations. In addition, exons 4-11 of the TP53 gene were sequenced. Statistical analyses were conducted to identify associations between mutations and selected clinico-pathological characteristics and risk habits. RESULTS: Oncogenic mutations were detected in PIK3CA (5.7%) and HRAS (2.4%). Mutations in TP53 were observed in 27.7% (31/112) of the OSCC specimens. Oncogenic mutations were found more frequently in non-smokers (p = 0.049) and TP53 truncating mutations were more common in patients with no risk habits (p = 0.019). Patients with mutations had worse overall survival compared to those with absence of mutations; and patients who harbored DNA binding domain (DBD) and L2/L3/LSH mutations showed a worse survival probability compared to those patients with wild type TP53. The majority of the oncogenic and TP53 mutations were G:C > A:T and A:T > G:C base transitions, regardless of the different risk habits. CONCLUSION: Hotspot oncogenic mutations which are frequently present in common solid tumors are exceedingly rare in OSCC. Despite differences in risk habit exposure, the mutation frequency of PIK3CA and HRAS in Asian OSCC were similar to that reported in OSCC among Caucasians, whereas TP53 mutations rates were significantly lower. The lack of actionable hotspot mutations argue strongly for the need to comprehensively characterize gene mutations associated with OSCC for the development of new diagnostic and therapeutic tools.

Genome wide analysis of chromosomal alterations in oral squamous cell carcinomas revealed over expression of MGAM and ADAM9.

Despite the advances in diagnosis and treatment of oral squamous cell carcinoma (OSCC), mortality and morbidity rates have not improved over the past decade. A major drawback in diagnosis and treatment of OSCC is the lack of knowledge relating to how genetic instability in oral cancer genomes affects oral carcinogenesis. Hence, the key aim of this study was to identify copy number alterations (CNAs) that may be cancer associated in OSCC using high-resolution array comparative genomic hybridization (aCGH). To our knowledge this is the first study to use ultra-high density aCGH microarrays to profile a large number of OSCC genomes (n = 46). The most frequently amplified CNAs were located on chromosome 11q11(52%), 2p22.3(52%), 1q21.3-q22(54%), 6p21.32(59%), 20p13(61%), 7q34(52% and 72%),8p11.23-p11.22(80%), 8q11.1-q24.4(54%), 9q13-q34.3(54%), 11q23.3-q25(57%); 14q21.3-q31.1(54%); 14q31.3-q32.33(57%), 20p13-p12.3(54%) and 20q11.21-q13.33(52%). The most frequently deleted chromosome region was located on 3q26.1 (54%). In order to verify the CNAs from aCGH using quantitative polymerase chain reaction (qPCR), the three top most amplified regions and their associated genes, namely ADAM5P (8p11.23-p11.22), MGAM (7q34) and SIRPB1 (20p13.1), were selected in this study. The ADAM5P locus was found to be amplified in 39 samples and deleted in one; MGAM (24 amplifications and 3 deletions); and SIRPB1 (12 amplifications, others undetermined). On the basis of putative cancer-related annotations, two genes, namely ADAM metallopeptidase domain 9 (ADAM9) and maltase-glucoamylase alpha-glucosidase (MGAM), that mapped to CNA regions were selected for further evaluation of their mRNA expression using reverse transcriptase qPCR. The over-expression of MGAM was confirmed with a 6.6 fold increase in expression at the mRNA level whereas the fold change in ADAM9 demonstrated a 1.6 fold increase. This study has identified significant regions in the OSCC genome that were amplified and resulted in consequent over-expression of the MGAM and ADAM9 genes that may be utilized as biological markers for OSCC.

Four-protein signature accurately predicts lymph node metastasis and survival in oral squamous cell carcinoma.

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.

Conservative neck dissection in oral cancer patients: a 5 year retrospective study in Malaysia.

OBJECTIVE: The impact of ablative oral cancer surgery was studied, with particular reference to recurrence and nodal metastasis, to assess survival probability and prognostic indicators and to elucidate if ethnicity influences the survival of patients. METHODS: Patients who underwent major ablative surgery of the head and neck region with neck dissection were identified and clinical records were assessed. Inclusion criteria were stage I-IV oral and oropharyngeal malignancies necessitating resection with or without radiotherapy from 2004 to 2009. All individuals had a pre-operative assessment prior to the surgery. The post operative assessment period ranged from 1 year to 5 years. Survival distributions were analyzed using Kaplan-Meier curves. RESULTS: 87 patients (males:38%; females:62%) were included in this study, with an age range of 21-85 years. Some 78% underwent neck dissections while 63% had surgery and radiotherapy. Nodal recurrence was detected in 5.7% while 20.5% had primary site recurrence within the study period. Kaplan-Meier survival analysis revealed that the median survival time was 57 months. One year overall survival (OS) rate was 72.7% and three year overall survival rate dropped to 61.5%. On OS analysis, the log-rank test showed a significant difference of survival between Malay and Chinese patients (Bonferroni correction p=0.033). Recurrence-free survival (RFS) analysis revealed that 25% of the patients have reached the event of recurrence at 46 months. One year RFS rate was 85.2% and the three year survival rate was 76.1%. In the RFS analysis, the log-rank test showed a significant difference in the event of recurrence and nodal metastasis (p<0.001). CONCLUSION: Conservative neck is effective, in conjunction with postoperative radiotherapy, for control of neck metastases. Ethnicity appears to influence the survival of the patients, but a prospective trial is required to validate this.

Significant association of high-risk human papillomavirus (HPV) but not of p53 polymorphisms with oral squamous cell carcinomas in Malaysia.

PURPOSE: The purpose of this study was to evaluate the role of HPV and p53 polymorphisms in oral squamous cell carcinomas (OSCC) affecting Malaysian population. METHODS: We analysed frozen samples from 105 OSCC as well as 105 oral specimens derived from healthy individuals. PCR assays targeting two regions of the virus were used. PCR amplification for the analysis of p53 codon 72 arginine/proline alleles was carried out in a separate reaction. RESULTS: HPV DNA was detected in 51.4% OSCC samples, while 24.8% controls were found to be HPV positive. HPV was found to be significantly associated with OSCC (P < 0.001, OR = 4.3 after adjustment for habits) when compared to controls. High-risk HPV was found to be significantly associated with OSCC cases (P < 0.05). Demographic profiles of age, gender, race and habits were not associated with HPV presence in cases and controls. However, significantly less HPV positivity was seen in poorly differentiated compared to well-differentiated OSCCs. No significant association was found between HPV positivity and p53 polymorphisms in cases and control groups. Additionally, we found no association of codon 72 polymorphism with oral cancer. CONCLUSIONS: This study indicates that high-risk HPV infection is one of the contributing factors for OSCCs. HPV 16 was the predominant type found in Malaysian patients with OSCC. Further, we did not find any association between p53 codon 72 polymorphism and HPV infection or between the p53 polymorphism and the risk of oral cancer.

Establishment and characterization of Asian oral cancer cell lines as in vitro models to study a disease prevalent in Asia.

We have established 3 cell lines ORL-48, -115 and -136 from surgically resected specimens obtained from untreated primary human oral squamous cell carcinomas of the oral cavity. The in vitro growth characteristics, epithelial origin, in vitro anchorage independency, human papilloma-virus (HPV) infection, microsatellite instability status, karyotype and the status of various cell cycle regulators and gatekeepers of these cell lines were investigated. All 3 cell lines grew as monolayers with doubling times ranging between 26.4 and 40.8 h and were immortal. Karyotyping confirmed that these cell lines were of human origin with multiple random losses and gains of entire chromosomes and regions of chromosomes. Immunohistochemistry staining of cytokeratins confirmed the epithelial origin of these cell lines, and the low degree of anchorage independency expressed by these cell lines suggests non-transformed phenotypes. Genetic analysis identified mutations in the p53 gene in all cell lines and hypermethylation of p16INK4a in ORL-48 and -136. Analysis of MDM2 and EGFR expression indicated MDM2 overexpression in ORL-48 and EGFR overexpression in ORL-136 in comparison to the protein levels in normal oral keratinocytes. Analysis of the BAT-26 polyadenine repeat sequence and MLH-1 and MSH-2 repair enzymes demonstrated that all 3 cell lines were microsatellite stable. The role of HPV in driving carcinogenesis in these tumours was negated by the absence of HPV. Finally, analysis of the tissues from which these cell lines were derived indicated that the cell lines were genetically representative of the tumours, and, therefore, are useful tools in the understanding of the molecular changes associated with oral cancers.