Genome-wide profiling of oral squamous cell carcinoma

Identification of copy number alternation profiles in metastatic oral squamous carcinoma patients by using microarray-based comparative genomic hybridization: A study on Turkish patients

OBJECTIVE

Oral squamous cell carcinoma (OSCC) is a severe form of cancer affecting different anatomic sites of the oral cavity. OSCC ranks as the sixth most common cancer type with an increasing prevalence globally. However, the mechanisms of OSCC process at later stages are not well understood. In this study, we aimed to determine genetic alternations in metastatic OSCC patients to identify genomic changes occurred at metastatic phase of the disease.

MATERIAL AND METHODS

The Illumina CytoSNP-12 Array was used to determine copy number variations in OSCC cancer genome. Hybridization procedures were performed according to the manufacturer procedures (Illumina). Arrays were scanned on iScan System (Illumina). Data were analyzed using Illumina Genotyping module of Genome Studio software (version 1.2, Illumina). Multiple CNV algorithms and copy number alternations were accessed by Genome Studio. CNVs in whole genome were investigated by using a chromosomal heat map.

RESULTS

We reported that gains in 8q21.11-ter, 9p21.3, 13q14.11-ter, 13q13.3-ter and losses in 5q14.3-ter, 5q35 and 17p13.3-12 were associated with the development of OSCC. In addition, we also detected that deletion in 2q33.2-ter and 2q35-37.3 regions were also associated with OSCC metastasis process.

CONCLUSIONS

Our results were also showed that gains in 11q13.3-q13.4 and 2q13.2 chromosomal regions could promote the metastatic OSCC process. We believe that results of the study will help to find new biomarkers for diagnosis at later stage of OSCC.

Polyphenols in Oral Health: Homeostasis Maintenance, Disease Prevention, and Therapeutic Applications

Polyphenols, a class of bioactive compounds with phenolic structures, are abundant in human diets. They have gained attention in biomedical fields due to their beneficial properties, including antioxidant, antibacterial, and anti-inflammatory activities. Therefore, polyphenols can prevent multiple chronic or infectious diseases and may help in the prevention of oral diseases. Oral health is crucial to our well-being, and maintaining a healthy oral microbiome is essential for preventing various dental and systemic diseases. However, the mechanisms by which polyphenols modulate the oral microbiota and contribute to oral health are still not fully understood, and the application of polyphenol products lies in different stages. This review provides a comprehensive overview of the advancements in understanding polyphenols' effects on oral health: dental caries, periodontal diseases, halitosis, and oral cancer. The mechanisms underlying the preventive and therapeutic effects of polyphenols derived from dietary sources are discussed, and new findings from animal models and clinical trials are included, highlighting the latest achievements. Given the great application potential of these natural compounds, novel approaches to dietary interventions and oral disease treatments may emerge. Moreover, investigating polyphenols combined with different materials presents promising opportunities for developing innovative therapeutic strategies in the treatment of oral diseases.

TGF-β Signaling in Progression of Oral Cancer

Oral cancer is a common malignancy worldwide, accounting for 1.9% to 3.5% of all malignant tumors. Transforming growth factor β (TGF-β), as one of the most important cytokines, is found to play complex and crucial roles in oral cancers. It may act in a pro-tumorigenic and tumor-suppressive manner; activities of the former include cell cycle progression inhibition, tumor microenvironment preparation, apoptosis promotion, stimulation of cancer cell invasion and metastasis, and suppression of immune surveillance. However, the triggering mechanisms of these distinct actions remain unclear. This review summarizes the molecular mechanisms of TGF-β signal transduction, focusing on oral squamous cell and salivary adenoid systemic carcinomas as well as keratocystic odontogenic tumors. Both the supporting and contrary evidence of the roles of TGF-β is discussed. Importantly, the TGF-β pathway has been the target of new drugs developed in the past decade, some having demonstrated promising therapeutic effects in clinical trials. Therefore, the achievements of TGF-β pathway-based therapeutics and their challenges are also assessed. The summarization and discussion of the updated knowledge of TGF-β signaling pathways will provide insight into the design of new strategies for oral cancer treatment, leading to an improvement in oral cancer outcomes.

MFI2 upregulation promotes malignant progression through EGF/FAK signaling in oral cavity squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the predominant histological type of the head and neck squamous cell carcinoma (HNSCC). By comparing the differentially expressed genes (DEGs) in OSCC-TCGA patients with copy number variations (CNVs) that we identify in OSCC-OncoScan dataset, we herein identified 37 dysregulated candidate genes. Among these potential candidate genes, 26 have been previously reported as dysregulated proteins or genes in HNSCC. Among 11 novel candidates, the overall survival analysis revealed that melanotransferrin (MFI2) is the most significant prognostic molecular in OSCC-TCGA patients. Another independent Taiwanese cohort confirmed that higher MFI2 transcript levels were significantly associated with poor prognosis. Mechanistically, we found that knockdown of MFI2 reduced cell viability, migration and invasion via modulating EGF/FAK signaling in OSCC cells. Collectively, our results support a mechanistic understanding of a novel role for MFI2 in promoting cell invasiveness in OSCC.

Pathogenesis and prognosis of primary oral squamous cell carcinoma based on microRNAs target genes: a systems biology approach

Oral squamous cell carcinoma (OSCC) is the most prevalent head and neck malignancy, with frequent cervical lymph-node metastasis, leading to a poor prognosis in OSCC patients. The present study aimed to identify potential markers, including microRNAs (miRNAs) and genes, significantly involved in the etiology of early-stage OSCC. Additionally, the main OSCC's dysregulated Gene Ontology annotations and significant signaling pathways were identified. The dataset GSE45238 underwent multivariate statistical analysis in order to distinguish primary OSCC tissues from healthy oral epithelium. Differentially expressed miRNAs (DEMs) with the criteria of p-value < 0.001 and |Log2 fold change| > 1.585 were identified in the two groups, and subsequently, validated targets of DEMs were identified. A protein interaction map was constructed, hub genes were identified, significant modules within the network were illustrated, and significant pathways and biological processes associated with the clusters were demonstrated. Using the GEPI2 database, the hub genes' predictive function was assessed. Compared to the healthy controls, main OSCC had a total of 23 DEMs. In patients with head and neck squamous cell carcinoma (HNSCC), upregulation of CALM1, CYCS, THBS1, MYC, GATA6, and SPRED3 was strongly associated with a poor prognosis. In HNSCC patients, overexpression of PIK3R3, GIGYF1, and BCL2L11 was substantially correlated with a good prognosis. Besides, “proteoglycans in cancer” was the most significant pathway enriched in the primary OSCC. The present study results revealed more possible mechanisms mediating primary OSCC and may be useful in the prognosis of the patients with early-stage OSCC.

Chrysophanol Suppresses Cell Growth via mTOR/PPAR-α Regulation and ROS Accumulation in Cultured Human Tongue Squamous Carcinoma SAS Cells

Oral cancer, a type of head and neck cancer, can pose a significant risk of death unless diagnosed and treated early. Alternative treatments are urgently needed owing to the high mortality rate, limitations of conventional treatments, and many complications. The anthraquinone compound chrysophanol acts as a tumor suppressor on some types of cancer cells. To date, it has not been clarified how chrysophanol affects human tongue squamous carcinoma. This study was aimed to examine the effects of chrysophanol on oral cancer treatment. The results show that chrysophanol caused cell death, reduced the expression of the mammalian target of rapamycin (mTOR)/peroxisome proliferator-activated receptor-alpha (PPAR-α), and increased reactive oxygen species (ROS) production. We also used two ion chelators, deferoxamine (DFO) and liproxstatin-1 (Lipro), to further determine whether chrysophanol inhibits cell growth and regulates mTOR/PPAR-α expression and ROS production, both of which are involved in iron homeostasis. The results show that DFO and Lipro reversed the increase in cell death, downregulation of mTOR/PPAR-α, and decrease in ROS accumulation. In conclusion, chrysophanol inhibits the growth of oral squamous cell carcinoma cells by modulating mTOR/PPAR-α and by causing ROS accumulation.

Lack of Salivary Long Non-Coding RNA XIST Expression Is Associated with Increased Risk of Oral Squamous Cell Carcinoma: A Cross-Sectional Study

Studies have shown that there is a disparity between males and females in south-east Asia with regard to oral cancer morbidity. A previous study found that oral cancer tissue showed loss of heterozygosity of the X-linked lncRNA XIST gene. We suggest that XIST may play an important role in oral cancer morbidity when associated with sex. Saliva contains proteins and RNAs that are potential biomarkers for the diagnosis of diseases. This study investigated salivary XIST expression and the correlation to clinical-pathological data among oral squamous cell carcinoma patients. Salivary XIST expression was only observed in females, and a high proportion of females with OSCC lack salivary lncRNA XIST expression (88%). The expression showed no correlation with alcohol consumption, betel quid chewing, or cigarette smoking habits. People lacking salivary lncRNA XIST expression had a significantly increased odds ratio of suffering from OSCC (OR = 19.556, p < 0.001), particularly females (OR = 33.733, p < 0.001). The ROC curve showed that salivary lncRNA XIST expression has acceptable discrimination accuracy to predict the risk of OSCC (AUC = 0.73, p < 0.01). Lack of salivary lncRNA XIST expression was associated with an increased risk of OSCC. We provided an insight into the role of salivary lncRNA XIST as a biomarker to predict the morbidity of OSCC.

Fluorouracil sensitivity in a head and neck squamous cell carcinoma with a somatic DPYD structural variant

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers worldwide and represents a heterogeneous group of tumors, the majority of which are treated with a combination of surgery, radiation, and chemotherapy. Fluoropyrimidine (5-FU) and its oral prodrug, capecitabine, are commonly prescribed treatments for several solid tumor types including HNSCC. 5-FU-associated toxicity is observed in ∼30% of treated patients and is largely caused by germline polymorphisms in DPYD, which encodes dihydropyrimidine dehydrogenase, a key enzyme of 5-FU catabolism and deactivation. Although the association of germline DPYD alterations with toxicity is well-described, the potential contribution of somatic DPYD alterations to 5-FU sensitivity has not been explored. In a patient with metastatic HNSCC, in-depth genomic and transcriptomic integrative analysis on a biopsy from a metastatic neck lesion revealed alterations in genes that are associated with 5-FU uptake and metabolism. These included a novel somatic structural variant resulting in a partial deletion affecting DPYD, a variant of unknown significance affecting SLC29A1, and homozygous deletion of MTAP. There was no evidence of deleterious germline polymorphisms that have been associated with 5-FU toxicity, indicating a potential vulnerability of the tumor to 5-FU therapy. The discovery of the novel DPYD variant led to the initiation of 5-FU treatment that resulted in a rapid response lasting 17 wk, with subsequent relapse due to unknown resistance mechanisms. This suggests that somatic alterations present in this tumor may serve as markers for tumor sensitivity to 5-FU, aiding in the selection of personalized treatment strategies.

Recent trends in predictive biomarkers for determining malignant potential of oral potentially malignant disorders

Despite of the tremendous advancements in the field of cancer prevention, detection and treatment, the overall prognosis of oral squamous cell carcinoma (OSCC) still remains poor. This can be partly imparted to the lack of early detection of oral potentially malignant disorders (OPMDs), especially those at a higher risk of progression into OSCC. Over years, various specific and non-specific markers have been introduced that could predict the malignant transformation of OPMDs; however detail information on these OPMD markers in a concise manner is lacking. Moreover, their use on daily clinical basis still remains questionable. With continuous research in the field of cytology and genomics, several contemporary biomarkers have been discovered that are not yet foregrounded and proved to be more promising than those used conventionally. Here, in the present paper, we overview several recently concluded predictive biomarkers with special emphasis on their role in molecular pathogenesis of OSCC transformation. These markers can be used for risk assessment of malignant transformation in patients with OPMDs as well as for prophylactic conciliation and fair management of the high-risk OPMD patient group.

c-MYC expression in T (III/IV) stage oral squamous cell carcinoma (OSCC) patients

Purpose: c-MYC has been noted in many tumor types, but its functional significance and clinical utility in oral squamous cell carcinoma (OSCC) are not well known. Here we studied the expression of c-MYC in correlation to clinical outcome in patients with oral squamous cell carcinoma. Methods: The current study, using immunohistochemical staining, first examined c-MYC expression in OSCC patients and further correlated its expression with clinicopathological parameters. Results: c-MYC was expressed in the majority of OSCC patients (n=133). The c-MYC expression is associated with histological grade (P=0.0205) of patients with oral squamous cell carcinoma. Multivariate Cox regression analysis revealed that TN stage (P<0.001), American Joint Committee on Cancer (AJCC) stage (P<0.0001), and tumor differentiation (P=0.0025) were independent factors for overall survival in patients with OSCC except for c-MYC expression (P>0.05). Multiplicative-scale interaction between T stage (III/IV) and low c-MYC expression on mortality risk was identified (P=0.0233). Kaplan-Meier survival analysis demonstrated that oral cancer patients (T III/IV stage) with high c-MYC expression had better survival than those with low and medium c-MYC expression (P=0.0270). Conclusion: Our data indicate that c-MYC is a potential biomarker that can be used as a therapeutic target for treating OSCC patients with T stage (III/IV).

Amplification of the EGFR and CCND1 Are Coordinated and Play Important Roles in the Progression of Oral Squamous Cell Carcinomas

Oral squamous cell carcinoma (OSCC) is a common cancer in Taiwan and worldwide. To provide some clues for clinical management of OSCC, 72 advanced-stage OSCCs were analyzed using two microarray platforms (26 cases with Affymetrix 500 K and 46 cases with Affymetrix SNP 6.0). Genomic identification of significant targets in cancer analyses were used to identify significant copy number alterations (CNAs) using a q-value cutoff of 0.25. Among the several significant regions, 12 CNAs were common between these two platforms. Two gain regions contained the well-known oncogenes EGFR (7p11.2) and CCND1 (11q13.3) and several known cancer suppressor genes, such as FHIT (3p14.2-p12.1), FAT1 (4q35.1), CDKN2A (9p21.3), and ATM (11q22.3-q24.3), reside within the 10 deletion regions. Copy number gains of EGFR and CCND1 were further confirmed by fluorescence in situ hybridization and TaqMan CN assay, respectively, in 257 OSCC cases. Our results indicate that EGFR and CCND1 CNAs are significantly associated with clinical stage, tumor differentiation, and lymph node metastasis. Furthermore, EGFR and CCND1 CNAs have an additive effect on OSCC tumor progression. Thus, current genome-wide CNA analysis provides clues for future characterization of important oncogenes and tumor suppressor genes associated with the behaviors of the disease.

Liposome-coated nano doxorubicin induces apoptosis on oral squamous cell carcinoma CAL-27 cells

OBJECTIVE

This study aims to investigate the apoptotic effect of Doxorubicin and its nano-formulated form (Doxil) on oral squamous cell carcinoma CAL-27 cells.

DESIGN

Cell viability using MTT assay, mode of cell death using fluorescence analysis, expression of the apoptotic marker caspase-3 using indirect ELISA technique and expression of C-Myc gene using reverse transcriptase and real time PCR.

RESULTS

Doxil treatment resulted in a higher percentage of apoptotic cells than doxorubicin treatment, while doxorubicin treatment resulted in a higher percentage of necrotic cells than Doxil treatment. Doxil-treated cells exhibited 3.38-fold higher caspase-3 levels than control cells, while doxorubicin significantly increased caspase-3 levels by 2.72-fold. The percentage of C-Myc mRNA inhibition was 27% in doxorubicin-treated cells and 41% in Doxil-treated cells.

CONCLUSIONS

Doxil exerted a higher apoptotic effect on CAL-27 cells compared to doxorubicin. It showed a higher increase in capase-3 level than doxorubicin and also exerted a more percentage of C-Myc mRNA inhibition.

Immune and genomic signatures in oral (head and neck) cancer

Head and neck squamous cell carcinoma (HNSCC) is responsible for a large number of deaths each year. Oral cancer is the most frequent subtype of HNSCC. Historically, oral cancer has been associated with an increase in the consumption of tobacco and alcohol products, seen especially in the Asian subcontinent. It has also been associated with infection by the human papilloma virus (HPV), particularly strain HPV16. Treatment usually involves a multidisciplinary approach of surgery combined with chemotherapy and radiation. The advent of immunotherapy has broadened the scope for treatment. A better immune response to the tumour can also elicit the action of other therapeutic approaches. A heightened immune response, on the other hand, can lead to resistant tumour formation through the process of immunoediting. Molecular profiling of the tumour microenvironment (TME) can provide us with better insight into the mechanism and progression of the disease, ultimately opening up new therapeutic options. High-throughput molecular profiling techniques over the past decade have enabled us to appreciate the heterogeneity of the TME. In this review, we will be describing the clinicopathological role of the immune and genomic landscape in oral cancer. This study will update readers on the several immunological and genetic factors that can play an important function as predictive and prognostic biomarkers in various forms of head and neck cancer, with a special emphasis on oral carcinoma.

Specific Targeting of MTAP-Deleted Tumors with a Combination of 2'-Fluoroadenine and 5'-Methylthioadenosine

Homozygous deletion of the methylthioadenosine phosphorylase (MTAP) gene is a frequent event in a wide variety of human cancers and is a possible molecular target for therapy. One potential therapeutic strategy to target MTAP-deleted tumors involves combining toxic purine analogues such as 6'-thioguanine (6TG) or 2'-fluoroadenine (2FA) with the MTAP substrate 5'-deoxy-5'-methylthioadenosine (MTA). The rationale is that excess MTA will protect normal MTAP+ cells from purine analogue toxicity because MTAP catalyzes the conversion of MTA to adenine, which then inhibits the conversion of purine base analogues into nucleotides. However, in MTAP- tumor cells, no protection takes place because adenine is not formed. Here, we examine the effects of 6TG and 2FA in combination with MTA in vitro and in vivoIn vitro, MTA protected against both 6TG and 2FA toxicity in an MTAP-dependent manner, shifting the IC50 concentration by one to three orders of magnitude. However, in mice, MTA protected against toxicity from 2FA but failed to protect against 6TG. Addition of 100 mg/kg MTA to 20 mg/kg 2FA entirely reversed the toxicity of 2FA in a variety of tissues and the treatment was well tolerated by mice. The 2FA+MTA combination inhibited tumor growth of four different MTAP- human tumor cell lines in mouse xenograft models. Our results suggest that 2FA+MTA may be a promising combination for treating MTAP-deleted tumors.Significance: Loss of MTAP occurs in about 15% of all human cancers; the MTAP protection strategy presented in this study could be very effective in treating these cancers. Cancer Res; 78(15); 4386-95. ©2018 AACR.

An update of knowledge on cortactin as a metastatic driver and potential therapeutic target in oral squamous cell carcinoma

Cortactin is a protein encoded by the CTTN gene, localized on chromosome band 11q13. As a result of the amplification of this band, an important event in oral carcinogenesis, CTTN is also usually amplified, promoting the frequent overexpression of cortactin. Cortactin enhances cell migration in oral cancer, playing a key role in the regulation of filamentous actin and of protrusive structures (invadopodia and lamellipodia) on the cell membrane that are necessary for the acquisition of a migratory phenotype. We also analyze a series of emerging functions that cortactin may exert in oral cancer (cell proliferation, angiogenesis, regulation of exosomes, and interactions with the tumor microenvironment). We review its molecular structure, its most important interactions (with Src, Arp2/3 complex, and SH3-binding partners), the regulation of its functions, and its specific oncogenic role in oral cancer. We explore the mechanisms of its overexpression in cancer, mainly related to genetic amplification. We analyze the prognostic implications of the oncogenic activation of cortactin in potentially malignant disorders and in head and neck cancer, where it appears to be relevant in the development of lymph node metastasis. Finally, we discuss its usefulness as a therapeutic target and suggest future research lines.

MicroRNA-1294 inhibited oral squamous cell carcinoma growth by targeting c-Myc

Oral squamous cell carcinoma (OSCC) is the predominant histological type of oral cancer. The 5-year survival rate of OSCC is only ~50%. c-Myc is a known oncogene and target gene in various cancer types, including OSCC. The presnet study revealed that c-Myc is one of the target genes of miR-1294. Results indicated lower levels of miR-1294 in OSCC tissues samples collected from 24 patients with OSCC. Notably, overexpression of miR-1294 inhibited proliferation and migration in OSCC cell lines and inhibition of miR-1294 promoted cell growth and migration in OSCC cell lines. Moreover, miR-1294 can target the 3′UTR of c-Myc, as we identified a negative correlation between c-Myc mRNA expression and miR-1294 expression in 24 OSCC tissues. In conclusion, the data demonstrate the tumor suppressive role of miR-1294 in OSCC.

VCAM1-targeted RNA interference inhibits the proliferation of human oral squamous carcinoma HN12 cells

In the present study, RNA interference (RNAi) was used to investigate the effect of vascular cell adhesion molecule 1 (VCAM1) silencing on the proliferation of human oral squamous carcinoma HN12 cells. HN12 cells were divided into three groups: The untreated blank control cell group (CK), the negative control group transfected with non-homologous vector (NC) and the positive group transfected with the target sequence VCAM1 small hairpin RNA (KD). Reverse-transcription polymerase chain reaction and western blot analysis were used to examine the effects of VCAM1-knockdown on the mRNA expression of VCAM1 and subsequent protein expression. Furthermore, the HN12 cell growth inhibition rate was detected using the cell counting kit-8 method. The VCAM1-targeted lentiviral vector RNAi significantly inhibited VCAM1 mRNA, and subsequent protein, expression. Compared with the NC group, the VCAM1 gene knockdown efficiency was ~85%, while the expression level of VCAM1 protein was reduced by ~74% in KD group cells. In addition, cell growth was significantly inhibited in the KD group, with a growth inhibition rate of ~34%. Therefore, this targeted lentiviral vector RNAi effectively inhibited VCAM1 gene, and subsequent protein, expression, as well as the proliferation of oral squamous carcinoma cells. These results may provide an experimental reference for the diagnosis and treatment of oral squamous cell carcinoma.

C-MYC and BCL-2 mediate YAP-regulated tumorigenesis in OSCC

Transcriptional co-activator Yes-associated protein (YAP) is a key oncogene in mammalian cells. The present understanding of YAP in oral squamous cells carcinoma (OSCC) remains unclear. The purpose of this study is to investigate the effects of YAP on proliferation and apoptosis in OSCC and the molecular mechanism. The results showed the expression level of YAP was higher in OSCC tissues than that in adjacent normal tissues. Knockdown of YAP in CAL27 cell lines prohibited cell proliferation while augmented apoptosis. Conversely, overexpression of YAP protected cells from apoptosis and promoted cell proliferation. Moreover, C-MYC and BCL-2 mRNA and protein levels were altered due to the differential expression of YAP. Subsequent Verteporfin treatment in CAL27 cells revealed that the transcription and translation of BCL-2 and C-MYC both decreased. In a tumor xenograft model, knockdown of YAP suppressed tumor growth of CAL27 in vivo, while YAP overexpression promoted the tumor growth. These results suggest that YAP is a crucial regulator that exerts pro-proliferation and anti-apoptosis effects in OSCC through actions affecting the cell cycle and intrinsic apoptotic signaling. Thus YAP could potentially serve as a valuable molecular biomarker or therapeutic target in the treatment of OSCC.

Genomic predictive model for recurrence and metastasis development in head and neck squamous cell carcinoma patients

The head and neck squamous cell carcinoma (HNSCC) population consists mainly of high-risk for recurrence and locally advanced stage patients. Increased knowledge of the HNSCC genomic profile can improve early diagnosis and treatment outcomes. The development of models to identify consistent genomic patterns that distinguish HNSCC patients that will recur and/or develop metastasis after treatment is of utmost importance to decrease mortality and improve survival rates. In this study, we used array comparative genomic hybridization data from HNSCC patients to implement a robust model to predict HNSCC recurrence/metastasis. This predictive model showed a good accuracy (>80%) and was validated in an independent population from TCGA data portal. This predictive genomic model comprises chromosomal regions from 5p, 6p, 8p, 9p, 11q, 12q, 15q and 17p, where several upstream and downstream members of signaling pathways that lead to an increase in cell proliferation and invasion are mapped. The introduction of genomic predictive models in clinical practice might contribute to a more individualized clinical management of the HNSCC patients, reducing recurrences and improving patients’ quality of life. The power of this genomic model to predict the recurrence and metastases development should be evaluated in other HNSCC populations.

Phosphoglycerate Mutase 1 Predicts the Poor Prognosis of Oral Squamous Cell Carcinoma and is Associated with Cell Migration

Oral squamous cell carcinoma (OSCC) is a common malignant tumor with high metastatic potential. However, no good biomarker has been identified to refine which subtype is of high metastatic potential to make decisions regarding the elective and therapeutic management of lymphatic metastases. In this study, we investigated the role of the metabolic enzyme phosphoglycerate mutase 1 (PGAM1) in OSCC. PGAM1 expression was examined in tissue samples of 122 OSCC patients using immunohistochemistry, and the correlation between clinicopathological expression and PGAM1 expression was determined. Survival curves were generated using the Kaplan-Meier method, and multivariate analysis was performed by the Cox proportional hazards model. Moreover, PGAM1 was knocked down in the OSCC cell lines Cal27 and HN12, followed by determination of the change in cell migration and signaling pathways. PGAM1 expression is correlated with age, lymphatic metastasis and tumor recurrence and is closely associated with poor overall survival (OS) and disease-free survival (DFS). Intriguingly, PGAM1 is an independent risk factor for OS and DFS. After knocking down PGAM1 in Cal27 and HN12 cells, cell migration was remarkably decreased along with signaling pathway molecules, such as proto-oncogene c-SRC (SRC), Focal adhesion kinase (FAK) and Paxillin. The effect on cell migration was abolished following pretreatment with an SRC inhibitor. This study suggested that PGAM1 is a poor prognostic biomarker of OSCC and may be used to select patients of high metastatic potential in the clinic, and PGAM1 promotes the migration of OSCC cells is associated with the SRC pathway.

Cinnamomum cassia essential oil and its major constituent cinnamaldehyde induced cell cycle arrest and apoptosis in human oral squamous cell carcinoma HSC-3 cells

Cinnamomum cassia essential oil (CC-EO) has various functional properties, such as anti-microbial, hypouricemic, anti-tyrosinase and anti-melanogenesis activities. The present study aimed to evaluate the anti-cancer activities of CC-EO and its major constituent, cinnamaldehyde, in human oral squamous cell carcinoma HSC-3 cells. Determination of the cell viability, apoptotic characteristics, DNA damage, cell cycle analysis, reactive oxygen species (ROS) production, mitochondrial membrane potential, cytosolic Ca²⁺ level and intracellular redox status were performed. Our results demonstrated that CC-EO and cinnamaldehyde significantly decreased cell viability and caused morphological changes. The cell cycle analysis revealed that CC-EO and cinnamaldehyde induced G2/M cell cycle arrest in HSC-3 cells. The apoptotic characteristics (DNA laddering and chromatin condensation) and DNA damage were observed in the CC-EO-treated and cinnamaldehyde-treated HSC-3 cells. Moreover, CC-EO and cinnamaldehyde promoted an increase in cytosolic Ca²⁺ levels, induced mitochondrial dysfunction and activated cytochrome c release. The results of ROS production and intracellular redox status demonstrated that CC-EO and cinnamaldehyde significantly increased the ROS production and thiobarbituric acid reactive substance levels, and the cellular glutathione content and glutathione peroxidase activity were significantly reduced in HSC-3 cells. Our results suggest that CC-EO and cinnamaldehyde may possess anti-oral cancer activity in HSC-3 cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 456-468, 2017.

Enhanced cell migration and apoptosis resistance may underlie the association between high SERPINE1 expression and poor outcome in head and neck carcinoma patients

High SERPINE1 expression is a common event in head and neck squamous cell carcinoma (HNSCC); however, whether it plays a role in determining clinical outcome remains still unknown. We studied SERPINE1 as a prognostic marker in two HNSCC patient cohorts. In a retrospective study (n = 80), high expression of SERPINE1 was associated with poor progression-free (p = 0.022) and cancer-specific (p = 0.040) survival. In a prospective study (n = 190), high SERPINE1 expression was associated with poor local recurrence-free (p = 0.022), progression-free (p = 0.002) and cancer-specific (p = 0.006) survival. SERPINE1 expression was identified as an independent risk factor for progression-free survival in patients treated with chemo-radiotherapy or radiotherapy (p = 0.043). In both patient cohorts, high SERPINE1 expression increased the risk of metastasis spread (p = 0.045; p = 0.029). The association between SERPINE1 expression and survival was confirmed using the HNSCC cohort included in The Cancer Genome Atlas project (n = 507). Once again, patients showing high expression had a poorer survival (p < 0.001). SERPINE1 over-expression in HNSCC cells reduced cell proliferation and enhanced migration. It also protected cells from cisplatin-induced apoptosis, which was accompanied by PI3K/AKT pathway activation. Downregulation of SERPINE1 expression had the opposite effect. We propose SERPINE1 expression as a prognostic marker that could be used to stratify HNSCC patients according to their risk of recurrence.

Usefulness of a fluorescence visualization system for the detection of oral precancerous and early cancerous lesions

Early detection of precancerous and early cancerous lesions could greatly reduce both the mortality and morbidity of oral cancer. The objective of this study was to analyze a fluorescence visualization (FV) system for the detection of precancerous and early cancerous lesions in rat tongue carcinogenesis and human oral cancerous lesions using for the first time a 4NQO rat model and human tissue. Based on the results from the rat tongue carcinogenesis model, under direct FV, the normal oral mucosa emitted various shades of pale green autofluorescence. In the precancerous and early cancerous cases, the lesion appeared as an irregular dark area. Histological examination of the lesions showed that the VELscope system had a sensitivity of 95% and specificity of 100% in discriminating normal mucosa from dysplasia/carcinoma in situ (CIS) or invasive carcinoma. The proliferating cell nuclear antigen (PCNA) protein level was gradually increased with progression of carcinogenic transformation. Furthermore, the results of PCNA and FV loss (FVL) were correlated. Next, results from 17 patients were also presented. Histological examination of the lesions showed that the VELscope system had a sensitivity of 95% and specificity of 100% in discriminating normal mucosa from severe dysplasia/CIS or invasive carcinoma. There were no normal epithelium cells in any of the FVL regions. Furthermore, to clarify the usefulness of FV compared to vital staining with iodine, we investigated the surgical margins of early oral squamous cell carcinoma (OSCC) tissues and compared the FVL and iodine unstained area (IU). The percentage of various types of dysplasia were almost equal when comparing the FVL and IU. These results suggest that this direct FV device has the potential for simple, cost-effective screening, detection and margin determination of oral precancerous and early cancerous lesions.

Triptolide represses oral cancer cell proliferation, invasion, migration, and angiogenesis in co-inoculation with U937 cells

Objectives

Advanced oral cancer is a major public health concern because of a lack of effective prevention and treatment. Triptolide (TPL), a diterpenoid triepoxide derived from the Chinese herb Tripterygium wilfordii, has been demonstrated to possess strong anticancer properties. In this study, we investigated whether TPL exerts anticancer effects on the tumor microenvironment of head and neck squamous cell carcinoma (HNSCC).

Materials and methods

Human macrophage-like U937 cells were co-inoculated with oral cancer SAS cells in a noncontact transwell coculture system. Cytokine expression was detected using ELISA, and cell proliferation was detected using methylene blue. RNA levels were detected using qPCR. Protein levels were detected using Western blot analysis. In vivo experiments involved using xenografted NOD/SCID mice.

Results

Our results demonstrated that TPL inhibited the growth of SAS cells co-inoculated with U937 cells in vitro and in vivo. TPL inhibited the invasion, migration ability, and angiogenesis of SAS cells co-inoculated with U937 cells. Expression of cytokines IL-6, IL-8, and TNF-α was induced by co-inoculation, but TPL repressed their expression.

Conclusion

TPL suppressed the expression of cytokines IL-6, IL-8, and TNF-α, as well as tumor growth, invasion, migration, and angiogenesis in the co-inoculation of human tongue cancer cells with macrophage-like U937 cells.

Clinical relevance

TPL is a potential candidate among novel chemotherapeutic agents or adjuvants for modulating tumor-associated macrophages in a tumor microenvironment of HNSCC.

Saliva proteome profiling reveals potential salivary biomarkers for detection of oral cavity squamous cell carcinoma

Oral cavity squamous cell carcinoma (OSCC), which is frequently associated with poor prognosis and mortality, is a leading cause of cancer-related death worldwide. Discovery of body fluid accessible biomarkers is needed to improve OSCC screening. To this end, we profiled proteomes of saliva from the healthy volunteers, the individuals with oral potentially malignant disorders (OPMD), and the OSCC patients by means of SDS-PAGE coupled with LC-MS/MS. In the control, the OPMD, and the OSCC groups, 958, 845, and 1030 salivary proteins were detected, respectively. With spectral counting-based label-free quantification, 22 overexpressed salivary proteins were identified in the OSCC group compared with the healthy controls and the OPMD individuals. Among them, resistin (RETN) was subjected to further validation with an independent cohort using ELISA. The data confirmed that the salivary RETN levels in the OSCC patients were significantly higher than that in the healthy or in the OPMD group. Moreover, the elevated levels of salivary RETN were highly correlated with late-stage primary tumors, advanced overall stage, and lymph-node metastasis. Our results not only reveal that profiling of saliva proteome is feasible for discovery of OSCC biomarkers, but also identify RETN as a potential salivary biomarker for OSCC detection.

Genome-Wide Loss of Heterozygosity and DNA Copy Number Aberration in HPV-Negative Oral Squamous Cell Carcinoma and Their Associations with Disease-Specific Survival

Oral squamous cell cancer of the oral cavity and oropharynx (OSCC) is associated with high case-fatality. For reasons that are largely unknown, patients with the same clinical and pathologic staging have heterogeneous response to treatment and different probability of recurrence and survival, with patients with Human Papillomavirus (HPV)-positive oropharyngeal tumors having the most favorable survival. To gain insight into the complexity of OSCC and to identify potential chromosomal changes that may be associated with OSCC mortality, we used Affymtrix 6.0 SNP arrays to examine paired DNA from peripheral blood and tumor cell populations isolated by laser capture microdissection to assess genome-wide loss of heterozygosity (LOH) and DNA copy number aberration (CNA) and their associations with risk factors, tumor characteristics, and oral cancer-specific mortality among 75 patients with HPV-negative OSCC. We found a highly heterogeneous and complex genomic landscape of HPV-negative tumors, and identified regions in 4q, 8p, 9p and 11q that seem to play an important role in oral cancer biology and survival from this disease. If confirmed, these findings could assist in designing personalized treatment or in the creation of models to predict survival in patients with HPV-negative OSCC.

Immortalization of epithelial cells in oral carcinogenesis as revealed by genome-wide array comparative genomic hybridization: A meta-analysis

BACKGROUND

This purpose of this meta-analysis study was to identify the most frequent and potentially significant copy number alteration (CNA) in oral carcinogenesis.

METHODS

Seven oral squamous cell carcinoma (OSCC)-related publications, corresponding to 312 samples, were identified for this meta-analysis. The data were analyzed in a 4-step process that included the genome assembly coordination of multiple platforms, assignment of chromosomal position anchors, calling gains and losses, and functional annotation analysis.

RESULTS

Gains were more frequent than losses in the entire dataset. High-frequency gains were identified in chromosomes 5p, 14q, 11q, 7p, 17q, 20q, 8q, and 3q, whereas high-frequency losses were identified in chromosomes 3p, 8p, 6p, 18q, and 4q. Ingenuity pathway analysis showed that the top biological function was associated with immortalization of the epithelial cells (p = 1.93E-04).

CONCLUSION

This study has identified multiple recurrent CNAs that are involved in various biological annotations associated with oral carcinogenesis. © 2015 Wiley Periodicals, Inc. Head Neck 38: E783-E797, 2016.

The response of head and neck squamous cell carcinoma to cetuximab treatment depends on Aurora kinase A polymorphism

Objectives

The aim of this study was to evaluate the efficiency of cetuximab-based anti-EGFR treatment and Aurora kinase A / B knockdown as a function of Aurora kinase polymorphism in HNSCC cell lines.

Materials and methods

First, protein expression of Aurora kinase A / B and EGFR and Aurora kinase A polymorphism were studied in tumour samples.

The survival and proliferation of Aurora kinase A homo- (Cal27) and heterozygous (HN) HNSCC cell lines was evaluated using a colony formation assay and a flow cytometric assay. Also, aneuploidy was determined. EGFR signalling pathway were visualised by western blotting.

Results

Immunohistochemistry revealed the overexpression of Aurora kinase A / B in HNSCC. The knockdown of each kinase caused a significant decrease in clonogenic survival, independent of Aurora kinase A polymorphism. In contrast, cetuximab treatment impaired clonogenic survival only in the Aurora kinase A-homozygous cell line (Cal27).

Conclusion

This study provides in vitro evidence for the predictive value of Aurora kinase A polymorphism in the efficiency of cetuximab treatment. Resistance to cetuximab treatment can be overcome by simultaneous Aurora kinase A/B knockdown.

Lin28B/Let-7 Regulates Expression of Oct4 and Sox2 and Reprograms Oral Squamous Cell Carcinoma Cells to a Stem-like State

Lin28, a key factor for cellular reprogramming and generation of induced pluripotent stem cell (iPSC), makes a critical contribution to tumorigenicity by suppressing Let-7. However, it is unclear whether Lin28 is involved in regulating cancer stem-like cells (CSC), including in oral squamous carcinoma cells (OSCC). In this study, we demonstrate a correlation between high levels of Lin28B, Oct4, and Sox2, and a high percentage of CD44(+)ALDH1(+) CSC in OSCC. Ectopic Lin28B expression in CD44(-)ALDH1(-)/OSCC cells was sufficient to enhance Oct4/Sox2 expression and CSC properties, whereas Let7 co-overexpression effectively reversed these phenomena. We identified ARID3B and HMGA2 as downstream effectors of Lin28B/Let7 signaling in regulating endogenous Oct4 and Sox2 expression. Let7 targeted the 3' untranslated region of ARID3B and HMGA2 and suppressed their expression, whereas ARID3B and HMGA2 increased the transcription of Oct4 and Sox2, respectively, through promoter binding. Chromatin immunoprecipitation assays revealed a direct association between ARID3B and a specific ARID3B-binding sequence in the Oct4 promoter. Notably, by modulating Oct4/Sox2 expression, the Lin28B-Let7 pathway not only regulated stemness properties in OSCC but also determined the efficiency by which normal human oral keratinocytes could be reprogrammed to iPSC. Clinically, a Lin28B(high)-Let7(low) expression pattern was highly correlated with high levels of ARID3B, HMGA2, OCT4, and SOX2 expression in OSCC specimens. Taken together, our results show how Lin28B/Let7 regulates key cancer stem-like properties in oral squamous cancers.

Role of SIRT1 in regulation of epithelial-to-mesenchymal transition in oral squamous cell carcinoma metastasis

BACKGROUND

The epithelial-to-mesenchymal transition (EMT) process results in a loss of cell-cell adhesion, increased cell mobility, and is crucial for enabling the metastasis of cancer cells. Recently, the enzyme SIRT1 has been implicated in a variety of physiological processes; however, its role in regulating oral cancer metastasis and EMT is not fully elucidated. Here, we propose a mechanism by which the enzyme sirtuin1 (SIRT1) regulates the EMT process in oral cancer by deacetylating Smad4 and repressing the effect of TGF-β signaling on matrix metalloproteinase-7 (MMP7).

METHODS

The roles of SIRT1 in tumor cell migration/invasion and metastasis to the lungs were investigated using the Boyden chamber assay and orthotopic injections, respectively. RNA interference was used to knockdown either SIRT1 or Smad4 expression in oral squamous cell carcinoma (OSCC) cell lines. Immunoblotting, zymographic assays, and co-immunoprecipitation were used to examine the effects of SIRT1 overexpression on MMP7 expression and activity, as well as on SIRT1/ Smad4 interaction.

RESULTS

We found that compared with normal human oral keratinocytes (HOKs), SIRT1 was underexpressed in OSCC cells, and also in oral cancer tissues obtained from 14 of 21 OSCC patients compared with expression in their matched normal tissues. Overexpression of SIRT1 inhibited migration of OSCC cells in vitro, as well as their metastasis to the lung in vivo. Furthermore, up-regulation of SIRT1 in metastatic OSCCs significantly inhibited the migration and invasion abilities of OSCC cells, while concomitantly increasing the expression of E-cadherin, and decreasing the expressions of mesenchymal markers. We also identified Smad4, a TGF-β-activated transcription factor, as a direct target protein for SIRT1. Overexpression of SIRT1 in OSCC cells led to decreased levels of acetylated Smad4, and inhibition of TGF-β-induced signaling. By associating and deacetylating Smad4, SIRT1 enzyme can influence MMP7 expression, MMP enzyme activity, and consequently, cell migration, invasion, and tumor metastasis in OSCCs.

CONCLUSIONS

These findings provide a valuable insight into the potential role of the SIRT1 enzyme in regulating cell migration and invasion in oral squamous cell carcinoma. Our findings suggest the SIRT1/Smad4/MMP7 pathway as a target for oral cancer driven by EMT.

Expression of MTAP inhibits tumor-related phenotypes in HT1080 cells via a mechanism unrelated to its enzymatic function

Methylthioadenosine Phosphorylase (MTAP) is a tumor suppressor gene that is frequently deleted in human cancers and encodes an enzyme responsible for the catabolism of the polyamine byproduct 5′deoxy-5′-methylthioadenosine (MTA). To elucidate the mechanism by which MTAP inhibits tumor formation, we have reintroduced MTAP into MTAP-deleted HT1080 fibrosarcoma cells. Expression of MTAP resulted in a variety of phenotypes, including decreased colony formation in soft-agar, decreased migration, decreased in vitro invasion, increased matrix metalloproteinase production, and reduced ability to form tumors in severe combined immunodeficiency mice. Microarray analysis showed that MTAP affected the expression of genes involved in a variety of processes, including cell adhesion, extracellular matrix interaction, and cell signaling. Treatment of MTAP-expressing cells with a potent inhibitor of MTAP’s enzymatic activity (MT-DADMe-ImmA) did not result in a MTAP− phenotype. This finding suggests that MTAP’s tumor suppressor function is not the same as its known enzymatic function. To confirm this, we introduced a catalytically inactive version of MTAP, D220A, into HT1080 cells and found that this mutant was fully capable of reversing the soft agar colony formation, migration, and matrix metalloproteinase phenotypes. Our results show that MTAP affects cellular phenotypes in HT1080 cells in a manner that is independent of its known enzymatic activity.

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.

A novel compound NSC745885 exerts an anti-tumor effect on tongue cancer SAS cells in vitro and in vivo

Objective

Oral squamous cell carcinoma (OSCC) is a prevalent cancer, especially in developing countries. Anthracyclines and their anthraquinone derivatives, such as doxorubicin, exhibit a cell growth inhibitory effect and have been used as anti-cancer drugs for many years. However, the cardiotoxicity of anthracycline antibiotics is a major concern in their clinical application. NSC745885 is a novel compound synthesized from 1,2-diaminoanthraquinone, which subsequently reacts with thionyl chloride and triethylamine. The present study aimed to investigate the anti-oral cancer potential and the safety of NSC745885.

Methods

We investigated the anti-cancer potential of NSC745885 in oral squamous carcinoma cell lines and in an in vivo oral cancer xenograft mouse model. The expression of apoptotic related genes were evaluated by real-time RT-PCR and western bloting, and the in vivo assessment of apoptotic marker were measured by immunohistochemical staining. The anti-tumor efficiency and safety between doxorubicin and NSC745885 were also compared.

Results

Our results demonstrated that NSC745885 exhibits anti-oral cancer activity through the induction of apoptosis in cancer cells and in tumor-bearing mice, and this treatment did not induce marked toxicity in experimental mice. This compound also exhibits a comparable anti-tumor efficiency and a higher safety in experimental mice when compared to doxorubicin.

Conclusions

The data of this study provide evidence for NSC745885 as a potential novel therapeutic drug for the treatment of human OSCC.

Salivary auto-antibodies as noninvasive diagnostic markers of oral cavity squamous cell carcinoma

BACKGROUND

Oral cavity squamous cell carcinoma (OSCC) is one of the most common cancers worldwide, and its incidence is still increasing. Approximately 50% of patients with OSCC die within 5 years after diagnosis, mostly ascribed to the fact that the majority of patients present advanced stages of OSCC at the time of diagnosis.

METHODS

To discover salivary biomarkers for ameliorating the detection of OSCC, herein, we developed a multiplexed bead-based platform to simultaneously detect auto-antibodies (auto-Abs) in salivary samples.

RESULTS

Compared with healthy individuals, the salivary levels of anti-p53, anti-survivin, anti-Hsp60, and anti-RPLP0 were significantly elevated in patients with OSCC. Noteworthily, the elevated levels of anti-p53, anti-survivin, and anti-Hsp60 were already observed in individuals with oral potentially malignant disorder. Moreover, the salivary levels of anti-p53, anti-survivin, anti-Hsp60, anti-RPLP0, and anti-CK8 were significantly elevated in patients with early-stage OSCC compared with those in healthy individuals. Most importantly, the use of a combined panel of salivary anti-p53, anti-survivin, anti-Hsp60, and anti-RPLP0 largely improves the detection of OSCC.

CONCLUSION

Collectively, our results reveal that the salivary auto-Abs are effective OSCC biomarkers and the four-auto-Ab panel provides a novel and practicable approach for OSCC screening.

IMPACT

This study provides the first evidence for the potential clinical application of salivary auto-Abs in OSCC diagnosis.

Genomic DNA copy number alterations from precursor oral lesions to oral squamous cell carcinoma

Oral cancer is a multifactorial disease in which both environmental and genetic factors contribute to the aetiopathogenesis. Oral cancer is the sixth most common cancer worldwide with a higher incidence among Melanesian and South Asian countries. More than 90% of oral cancers are oral squamous cell carcinoma (OSCC). The present study aimed to determine common genomic copy number alterations (CNAs) and their frequency by including 12 studies that have been conducted on OSCCs using array comparative genomic hybridization (aCGH). In addition, we reviewed the literature dealing with CNAs that drive oral precursor lesions to the invasive tumors. Results showed a sequential accumulation of genetic changes from oral precursor lesions to invasive tumors. With the disease progression, accumulation of genetic changes increases in terms of frequency, type and size of the abnormalities, even on different regions of the same chromosome. Gains in 3q (36.5%), 5p (23%), 7p (21%), 8q (47%), 11q (45%), 20q (31%) and losses in 3p (37%), 8p (18%), 9p (10%) and 18q (11%) were the most common observations among those studies. However, losses are less frequent than gains but it appears that they might be the primary clonal events in causing oral cancer.

Cyclin D1 expression is correlated with cell differentiation and cell proliferation in oral squamous cell carcinomas

The present study conducted an immunohistochemical investigation of cyclin D1 and Ki-67 expression in oral squamous cell carcinoma (SCC) to evaluate the correlations between cell differentiation, cell proliferation and metastasis, and the effect of anticancer drug medication and cyclin D1 expression. Cyclin D1 and Ki-67 were detected clearly in the nuclei of 35 SCC samples. No correlation between cyclin D1 protein expression and oral SCC differentiation was found. By contrast, the majority of metastatic foci (90%) exhibited strong cyclin D1 expression, whereas weak expression was observed in metastatic foci with pre-operative adjuvant therapy. Additionally, cyclin D1 and Ki-67 were expressed in basal to suprabasal cells of well-differentiated oral SCC, whereas cyclin D1-positive and Ki-67-negative cells were present in the highly-differentiated region, according to a double-immunostaining method. These results indicate that the expression of cyclin D1 protein plays a role in cell differentiation and cell proliferation in well-differentiated oral SCC.

Monocarboxylate transporter 4 facilitates cell proliferation and migration and is associated with poor prognosis in oral squamous cell carcinoma patients

Monocarboxylate transporter 4 (MCT4) is a cell membrane transporter of lactate. Recent studies have shown that MCT4 is over-expressed in various cancers; however, its role in cancer maintenance and aggressiveness has not been fully demonstrated. This study investigated the role of MCT4 in oral squamous cell carcinoma (OSCC), and found that it is highly expressed in OSCC patients by using immunohistochemistry. Moreover, this over-expression of MCT4 was closely associated with tumor size, TNM classification, lymphatic metastasis, distant metastasis and tumor recurrence, and also poor prognosis. To further study mechanisms of MCT4 in vitro, we used small-interfering RNA to silence its expression in OSCC cell lines. The results showed that knock-down of MCT4 decreased cell proliferation, migration, and invasion. The inhibition of proliferation was associated with down-regulation of p-AKT and p-ERK1/2, while decreased cell migration and invasion may be caused by down-regulation of integrin β4-SRC-FAK and MEK-ERK signaling. Together, these findings provide new insight into the critical role of MCT4 in cell proliferation and metastasis in OSCC.

NANOG expression correlates with differentiation, metastasis and resistance to preoperative adjuvant therapy in oral squamous cell carcinoma

NANOG protein, a transcription factor expressed in embryonic stem cells, is overexpressed in tumor development. Although studies investigating the function of NANOG in cancer have shown that it plays several roles, such as in cell proliferation, invasion and metastasis, the overall function of NANOG in cancer cells has remained elusive. In the present study, NANOG expression in oral squamous cell carcinoma (OSCC) was examined to determine its potential clinical significance. The expression of NANOG protein was assessed in 60 patients with OSCC by immunohistochemistry, and its correlation with clinicopathological factors and metastasis was evaluated. NANOG protein levels in human OSCC cell lines were determined by western blotting and immunofluorescence staining. NANOG protein expression was identified in 52 cases (86.7%) and expression levels were higher in primary foci of poorly differentiated OSCC than in those of well-differentiated OSCC, indicating that NANOG expression is associated with OSCC differentiation. Regardless of the differentiation levels of primary foci, NANOG expression levels in metastatic foci were extremely high. In addition, NANOG expression in metastatic foci was maintained at high levels following preoperative adjuvant therapy. Furthermore, NANOG protein was detected at an identical level in human OSCC cell lines. These data indicate that NANOG-expressing OSCC cells tend to metastasize and that metastatic tumors expressing NANOG may be resistant to preoperative adjuvant therapy, including chemoradiation. Thus, assessment of NANOG expression may assist the strategy for treatment of OSCC metastasis.