TP53 and CDKN2a mutations in never-smoker oral tongue squamous cell carcinoma

Oral Cavity Cancer Secondary to Dental Trauma: A Scoping Review

(1) Background: Oral cavity cancer represents the most common site of origin of head and neck mucosal malignancies. A few limited studies have suggested that chronic irritation, particularly in non-healing ulcers, and fibrotic tissue from poor dentition or ill-fitting dentures had a role in developing mouth cancer. This scoping review aims to evaluate the existing evidence concerning Oral Cavicty Cancer (OCC) in non-smokers/non-drinkers and the relationship with dental trauma. (2) Methods: A scoping review of the PubMed, Embase, and Web of Science databases was completed in adherence with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews checklist. (3) Results: Of the 33 articles that met inclusion, in 6 of them authors discussed the role of topography in dental trauma, in 11 articles authors discussed the carcinogenesis mechanism involved in chronic mucosal trauma, in 17 articles data on ill-fitting dentures was included, 4 studies dealt with the effect of broken/sharp teeth on mucosal damage, and in 7 studies the role of oral hygiene was covered. Less frequently discussed topics included gender, risk of neck nodes, and the role of potentially malignant oral disorders. (4) Conclusions: The available literature suggests a potential connection between chronic dental trauma and the development of OCC. Studies have highlighted factors such as denture use and ill-fitting dental appliances as contributors to an increased risk of oral cancer. Interestingly, we still miss data to support the hypothesis that women, particularly those without toxic habits like smoking or alcohol consumption, appear to be disproportionately affected by oral cancer related to chronic dental trauma.

Oral cavity cancer in young, non-smoking, and non-drinking patients: A contemporary review

Oral squamous cell carcinoma (OSCC) in non-smoking and non-drinking (NSND) individuals appears to be distinct from the traditional head and neck squamous cell carcinoma (HNSCC). The incidence of this subset is increasing, as are the number of studies examining its characteristics. NSND OSCC individuals tend to be younger (<45 years) compared to traditional HNSCC patients. The proportion of females in the NSND OSCC cohort is also higher. The tongue is the predominantly affected subsite. Studies have revealed several gene mutations and unique epigenomic profiles but no definitive genetic etiology. Transcriptomic analysis has not found any causative viral agents. Other proposed etiologies include chronic dental trauma, microbiome abnormalities, marijuana consumption, and genetic disorders. There are international efforts to determine the relative prognostic outcome of this unique cohort, but no consensus has been reached. Here, we review the incidence, demographics, subsite, possible etiologies, prognosis, and therapy implications of the NSND OSCC cohort.

Cyclin Dependent Kinase Inhibitor 2A Genetic and Epigenetic Alterations Interfere with Several Immune Components and Predict Poor Clinical Outcome

Cyclin dependent kinase inhibitor 2A (CDKN2A) is a well-known tumor suppressor gene as it functions as a cell cycle regulator. While several reports correlate the malfunction of CDKN2A with the initiation and progression of several types of human tumors, there is a lack of a comprehensive study that analyzes the potential effect of CDKN2A genetic alterations on the human immune components and the consequences of that effect on tumor progression and patient survival in a pan-cancer model. The first stage of the current study was the analysis of CDKN2A differential expression in tumor tissues and the corresponding normal ones and correlating that with tumor stage, grade, metastasis, and clinical outcome. Next, a detailed profile of CDKN2A genetic alteration under tumor conditions was described and assessed for its effect on the status of different human immune components. CDKN2A was found to be upregulated in cancerous tissues versus normal ones and that predicted the progression of tumor stage, grade, and metastasis in addition to poor prognosis under different forms of tumors. Additionally, CDKN2A experienced different forms of genetic alteration under tumor conditions, a characteristic that influenced the infiltration and the status of CD8, the chemokine CCL4, and the chemokine receptor CCR6. Collectively, the current study demonstrates the potential employment of CDKN2A genetic alteration as a prognostic and immunological biomarker under several types of human cancers.

Changing Epidemiology of Oral Cavity Cancer in the United States

OBJECTIVE

We aim to more accurately characterize the current distribution and rates of squamous cell carcinoma (SCC) cases across various oral cavity subsites in the United States.

STUDY DESIGN

Retrospective cohort.

SETTING

Database study evaluating cancer incidence in the United States from 2001 to 2017.

METHODS

We utilized the US Cancer Statistics Public Use Database, which includes deidentified cancer data reported to the Centers for Disease Control and Prevention's National Program of Cancer Registries and the National Cancer Institute's SEER (Surveillance, Epidemiology, and End Results), capturing 97% of newly diagnosed cancers. We restricted our analysis to SCC arising from oral cavity subsites from 2001 to 2017. We calculated trends in annual cancer incidence rates using SEER*Stat, as well as annual and average annual percentage change and joinpoints with the National Cancer Institute's Joinpoint program.

RESULTS

Most oral cavity SCC cases arise from the oral tongue (41.7%), followed equally by lip and floor of mouth (each 16.5%), gingival (10.6%), buccal (6.7%), retromolar trigone (5.6%), and hard palate (2.3%) involvement. The overall incidence of oral tongue SCC continues to rise with an average annual percentage change of 1.8% (95% CI, 1.6%-2.1%; P < .001), with a 2.3% increase among women. This increase is seen among males and females of all age groups. Cancers involving the gum, buccal mucosa, and hard palate were also found to be increasing in rate, albeit to a lesser degree and with substantially lower incidence.

CONCLUSIONS

The tongue is the most frequently involved subsite of oral cavity SCC and is increasing in incidence among males and females of all ages.

Early-onset oral cancer as a clinical entity: aetiology and pathogenesis

Oral squamous cell carcinoma (OSCC) is one of the most important medical and socio-economic problems in many of the developed countries worldwide, due to the high mortality. The incidence of OSCC among individuals under 45 years of age is growing every year; however, the aetiological factors and pathogenetic mechanisms are poorly understood. This review summarizes the available information regarding clinicopathological features, extrinsic and intrinsic aetiological factors, and the molecular and immune landscape of early-onset OSCC. This cancer shows high recurrence rates and is not associated with the aetiological factors specific to adult-onset OSCC. Young adults with OSCC are not infected with human papillomavirus and rarely consume alcohol or tobacco, but more frequently use smokeless tobacco. Data from single studies indicate the hereditary nature of early-onset OSCC: the KIR2DL1⁺-HLA-C2⁺ genotype and MMP-1 2 G allele are frequently detected in young patients. Early-onset OSCC shows specific genetic, epigenetic, transcriptomic, and proteomic changes. The tumour microenvironment in early-onset OSCC is tolerogenic rather than immunogenic. All of the data suggest that OSCC in young patients is a separate clinical entity with a specific aetiology and pathogenesis. Further studies are needed to reveal the causes and molecular targets of early-onset OSCC for the development of preventive and therapeutic strategies.

Nonsmoking and Nondrinking Oral Squamous Cell Carcinoma Patients: A Different Entity

Objective

Our goal was to analyze the demographic and pathologic characteristics as well as prognosis in nonsmoking and nondrinking (NSND) oral squamous cell carcinoma (SCC) patients compared with typical oral SCC patients.

Patients and Methods

A total of 353 patients were retrospectively enrolled and divided into two groups: the NSND group and the current smoking/current drinking (CSCD) group. Demographic, pathologic, and molecular data were compared between the two groups. The main research endpoints were locoregional control (LRC) and disease-specific survival (DSS).

Results

In the NSND group, 16.3%, 41.9%, and 53.5% of patients were aged no more than 40 years, were female, and had an educational background of high school or above compared to 3.7%, 6.0%, and 38.2% of patients in the CSCD group, respectively. A total of 15.1% of the NSND patients had SCC of the lower gingiva and floor of the mouth, which was lower than the 35.6% of patients in the CSCD group. CSCD patients were likely to have an advanced disease stage (48.7% vs 32.5%, p=0.042) and poorly differentiated cancer (26.6% vs 16.3%, p=0.042). The NSND patients had a mean Ki-67 index of 24.5%, which was lower than the mean of 35.7% in the CSCD patients. The two groups had no HPV infection and similar p16 expression (4.7% vs 10.1%, p=0.132), but there was higher expression of p53 (38.6% vs 17.4%, p<0.001) and p63 (59.9% vs 29.1%, p<0.001) in the CSCD group. The 5-year LRC rates for NSND patients and CSCD patients were 48% and 38%, respectively, and the difference was significant (p=0.048). The 5-year DSS rates for NSND patients and CSCD patients were 56% and 39%, respectively, and the difference was significant (p=0.047). Further, a Cox model confirmed the independence of smoking and drinking status for affecting LRC and DSS.

Conclusion

NSND oral SCC patients are a different entity. HPV infection has a limited role in carcinogenesis in NSND patients, and p16 expression is associated with worse locoregional control.

Clinicopathological characteristics of young never smoker females with oral cavity squamous cell carcinoma: A STROBE compliant retrospective observational study

Although the incidence of oral cavity cancer (OCC) in young never smoker females is increasing worldwide, there has been little research on the etiologies and characteristics of these patients to date. In this study, we sought to evaluate the annual increase in OCC incidence in young never smoker females (YNSF) in our hospital as well as to investigate their clinicopathological characteristics and different disease courses compared with those of other OCC patients. We retrospectively reviewed the medical records of patients who were diagnosed and treated at our tertiary referral hospital from 2006 to 2016. The annual incidence of OCC and proportion of YNSF (never smoker females aged 45 years or younger at the time of diagnosis) among the enrolled OCC patients were evaluated. The characteristics and prognosis of the YNSF group were analyzed using their clinicopathological and survival data. Among the OCC patients primarily enrolled in this study, the proportion of YNSF did not show significant annual increase. There were 32 YNSF among 354 OCC patients (9%), who were ultimately included for the analyses of clinicopathological characteristics and survival. However, YNSF showed no significant differences compared with other OCC patients, even in subgroup analyses for overall survival. Our study did not demonstrate significant changes in the annual proportion of YNSF among OCC patients. In addition, differences in neither clinicopathological characteristics nor survival were noted between YNSF and other OCC patients.

Genetic Mutations in Young Nonsmoking Patients With Oral Cavity Cancer: A Systematic Review

Objective

This investigation aims to review the known genetic mutations associated with oral cavity squamous cell carcinoma (OCSCC) in young adults with limited environmental risk factors (YLERs).

Data Sources

A comprehensive search strategy was designed to identify studies in MEDLINE (Ovid), Embase (Ovid), and Scopus from database inception to May 2017 that included adults ≤50 years of age with OCSCC and minimal tobacco use history (≤10 pack-years) who had their tumors genetically sequenced or mutational profiles analyzed.

Review Methods

Identified articles were screened by 2 reviewers. Quality of evidence was graded by the MINORS criteria for case-control studies; other studies were graded by assigning a level of evidence for gene mutation literature.

Results

Thirteen studies met our inclusion criteria, and 130 patients met our criteria for age and tobacco history. TP53 was the most commonly evaluated gene (10 of 13 studies) and the most frequently observed mutation. One study reported that nonsmokers had significantly fewer TP53 mutations, while 9 studies found no difference in the prevalence of TP53 mutations. No other mutations were found specific to this cohort.

Conclusions

TP53 mutations may occur at a similar rate in YLERs with OCSCC as compared with older patients or those with risk factors. However, few studies have aimed to characterize the genetic landscape of oral cavity tumors in this population, often with small sample sizes. Future studies are needed to explore unidentified genetic alterations leading to tumor susceptibility or alternative mechanisms of carcinogenesis.

Evidence for different molecular parameters in head and neck squamous cell carcinoma of nonsmokers and nondrinkers: Systematic review and meta-analysis on HPV, p16, and TP53

BACKGROUND

The goal of this review was to present an overview of the currently identified molecular parameters in head and neck squamous cell carcinoma (HNSCC) of nonsmokers and nondrinkers (NSND).

METHODS

Following the PRISMA guidelines, a systematic search was performed using the electronic databases PubMed, Embase, and Google Scholar.

RESULTS

Of the 902 analyzed unique studies, 74 were included in a quantitative synthesis and 24 in a meta-analysis. Human papillomavirus (HPV) was reported as a molecular parameter in 38 studies, followed by p16 and TP53 (23 and 14 studies, respectively). The variety of other molecular parameters concerned sporadic findings in small numbers of NSND.

CONCLUSIONS

HNSCC in NSND is more often related to HPV and p16 overexpression compared to tumors of smokers-drinkers. In a third of virus-negative tumors, TP53 mutations were detected with a mutational profile associated with aging and ultraviolet light exposure rather than to tobacco consumption.

Age and risk of recurrence in oral tongue squamous cell carcinoma: Systematic review

The incidence of oral tongue squamous cell carcinoma has been increasing in young patients (≤45 years) without a clear etiologic driver. It is unknown if younger patients have an increased risk of recurrence compared to older patients. A literature search was conducted through January 2020 using PubMed/MEDLINE, Embase, Cochrane, Scopus, Science Direct, and clinicaltrials.gov. This review was registered with PROSPERO (ID: CRD42020167498) and the PRISMA statement was followed. Studies were eligible for inclusion if they assessed risk of recurrence by age using a time-to-event analysis, used an age cutoff of ≤45 years or less for the younger cohort, and limited the analysis to the oral tongue subsite. Data were extracted independently by two reviewers using a form with a prespecified list of variables. There were 13 articles that met criteria for the qualitative synthesis (n = 1763 patients). The reported 5-year rates of disease-free survival ranged from 30% to 72% for the younger cohorts and 42% to 81% for the older cohorts. Three studies reported a statistically significant increased risk of recurrence in younger patients, three studies reported a nonsignificant increased risk in younger patients, and seven studies reported a similar risk in younger patients based on the time-to-event analyses. There may be an increased risk of recurrence for younger patients with oral tongue cancer. A definitive conclusion is precluded by limitations among individual studies, and additional research is warranted to examine this question.

A review of the most promising biomarkers for early diagnosis and prognosis prediction of tongue squamous cell carcinoma

BACKGROUND

There is a great interest in developing biomarkers to enhance early detection and clinical management of tongue squamous cell carcinoma (TSCC). However, the developmental path towards a clinically valid biomarker remains extremely challenging. Ideally, the initial key step in moving a newly discovered biomarker towards clinical implementation is independent replication. Therefore, the focus of this review is on biomarkers that consistently showed clinical relevance in two or more publications.

METHODS

We searched PubMed database for relevant papers across different TSCC sample sources, i.e., body fluids (saliva, serum/plasma) and tissues. No restriction regarding the date of publication was applied except for immunohistochemistry (IHC); only studies published between 2010 and June 2017 were included.

RESULTS

The search strategy identified 1429 abstracts, of which 96 papers, examining 150 biomarkers, were eventually included. Of these papers, 66% were exploratory studies evaluating single or a panel of biomarkers in one publication. Ultimately, based on studies that had undergone validation for their clinical relevance in at least two independent studies, we identified 10 promising candidates, consisting of different types of molecules (IL-6, IL-8, and Prolactin in liquid samples; HIF-1α, SOX2, E-cadherin, vimentin, MALAT1, TP53, and NOTCH1 in tissue biopsies) CONCLUSIONS: Although more exploratory research is needed with newer methods to identify biomarkers for TSCC, rigorous validation of biomarkers that have already shown unbiased assessment in at least two publications should be considered a high priority. Further research on these promising biomarkers or their combination in multi-institutional studies, could provide new possibilities to develop a specific panel for early diagnosis, prognosis, and individualized treatments.

Autologous reference types can confound the detection of somatic mutation in solid cancers

Vast number of somatic mutations has been proved to be affected by the factors of sequencing methods, analysis pipelines and validation methods. We here showed the effect of autologous reference types on the detection of cancer-associated somatic mutations with the somatic single nucleotide variations (SNVs) and clinical data of solid tumors from the Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC). The distribution of somatic SNVs was significantly different among groups of autologous references in 6 cancers detected by whole genome sequencing (WGS) and 5 cancers detected by the random sequencing of exonic regions selected from the genome (WXS), especially in protein coding region of 5 cancers with age, gender and TNM adjusted. In addition, only 60.24% (95% CI: 49.65%-70.83%) of the somatic SNVs called from normal blood by WXS were found in those called from normal solid tissue tested by WXS / WGS, while 31.78% (95%CI: 4.14%-59.42%) of the somatic SNVs called from normal tissue adjacent to primary by WXS were found in those from normal blood tested by WXS / WGS. These findings suggested that more representative types of normal tissues should be included in detection of cancer-associated somatic mutations.

Role of dental hardware in oral cavity squamous cell carcinoma in the low-risk nonsmoker nondrinker population

BACKGROUND

Oral cavity squamous cell carcinoma (SCC) arising in nonsmokers and nondrinkers remains poorly characterized. We hypothesized that these patients had prior exposure to metallic dental hardware.

METHODS

We utilized a questionnaire querying the lifetime oral health status of 54 patients. Demographics and extensive oral health history were collected.

RESULTS

The majority of patients (74%) had prior exposure to metallic dental hardware. The younger population with almost exclusively oral tongue cancer had a high prevalence of metallic orthodontic braces (40%) within 15 years before diagnosis. In the 51+ year age group, 82% had crowns, dental implants, and/or dentures with metallic elements.

CONCLUSION

Exposure to metallic dental hardware has increased in the past few decades given the rise of orthodontic braces and older adults retaining more teeth. Although this study does not prove a causal relationship between oral cavity SCC and dental hardware, this is a step toward identifying and investigating their role.

Establishment and characterization of an oral tongue squamous cell carcinoma cell line from a never-smoking patient

OBJECTIVE

The rising incidence of oral tongue squamous cell carcinoma (OTSCC) in patients who have never smoked and the paucity of knowledge of its biological behavior prompted us to develop a new cell line originating from a never-smoker.

MATERIALS AND METHODS

Fresh tumor tissue of keratinizing OTSCC was collected from a 44-year-old woman who had never smoked. Serum-free media with a low calcium concentration were used in cell culture, and a multifaceted approach was taken to verify and characterize the cell line, designated UCSF-OT-1109.

RESULTS

UCSF-OT-1109 was authenticated by STR DNA fingerprint analysis, presence of an epithelial marker EpCAM, absence of human papilloma virus (HPV) DNA, and SCC-specific microscopic appearance. Sphere-forming assays supported its tumorigenic potential. Spectral karyotype (SKY) analysis revealed numerical and structural chromosomal abnormalities. Whole-exome sequencing (WES) identified 46 non-synonymous and 13 synonymous somatic single-nucleotide polymorphisms (SNPs) and one frameshift deletion in the coding regions. Specifically, mutations of CDKN2A, TP53, SPTBN5, NOTCH2, and FAM136A were found in the databases. Copy number aberration (CNA) analysis revealed that the cell line loses chromosome 3p and 9p, but lacks amplification of 3q and 11q (as does HPV-negative, smoking-unrelated OTSCC). It also exhibits four distinctive focal amplifications in chromosome 19p, containing 131 genes without SNPs. Particularly, 52 genes showed >3- to 4-fold amplification and could be potential oncogenic drivers.

CONCLUSION

We have successfully established a novel OTSCC cell line from a never-smoking patient. UCSF-OT-1109 is potentially a robust experimental model of OTSCC in never-smokers.

Identification of an atypical etiological head and neck squamous carcinoma subtype featuring the CpG island methylator phenotype

Head and neck squamous cell carcinoma (HNSCC) is broadly classified into HNSCC associated with human papilloma virus (HPV) infection, and HPV negative HNSCC, which is typically smoking-related. A subset of HPV negative HNSCCs occur in patients without smoking history, however, and these etiologically 'atypical' HNSCCs disproportionately occur in the oral cavity, and in female patients, suggesting a distinct etiology. To investigate the determinants of clinical and molecular heterogeneity, we performed unsupervised clustering to classify 528 HNSCC patients from The Cancer Genome Atlas (TCGA) into putative intrinsic subtypes based on their profiles of epigenetically (DNA methylation) deregulated genes. HNSCCs clustered into five subtypes, including one HPV positive subtype, two smoking-related subtypes, and two atypical subtypes. One atypical subtype was particularly genomically stable, but featured widespread gene silencing associated with the 'CpG island methylator phenotype' (CIMP). Further distinguishing features of this 'CIMP-Atypical' subtype include an antiviral gene expression profile associated with pro-inflammatory M1 macrophages and CD8+ T cell infiltration, CASP8 mutations, and a well-differentiated state corresponding to normal SOX2 copy number and SOX2OT hypermethylation. We developed a gene expression classifier for the CIMP-Atypical subtype that could classify atypical disease features in two independent patient cohorts, demonstrating the reproducibility of this subtype. Taken together, these findings provide unprecedented evidence that atypical HNSCC is molecularly distinct, and postulates the CIMP-Atypical subtype as a distinct clinical entity that may be caused by chronic inflammation.

Human Papillomavirus 16 Infection and TP53 Mutation: Two Distinct Pathogeneses for Oropharyngeal Squamous Cell Carcinoma in an Eastern Chinese Population

Objectives

To investigate the clinicopathological characteristics, human papillomavirus (HPV) infection, p53 expression, and TP53 mutations in oropharyngeal squamous cell carcinoma (OPSCC) and determine their utility as prognostic predictors in a primarily eastern Chinese population.

Methods

The HPV infection status was tested via p16INK4A immunohistochemistry and validated using PCR, reverse blot hybridization and in situ hybridization (ISH) in 188 OPSCC samples. p53 expression levels and TP53 gene mutations were assessed through immunohistochemistry and sequencing, respectively. Clinicopathological characteristics and follow-up information were collected. Overall survival was estimated using the Log-rank test.

Results

Overall, 22 of the 188 OPSCC samples were associated with HPV infection. HPV16 was identified in all 22 samples, whereas no samples were positive for HPV18. All 22 HPV-associated OPSCC samples were p53 negative and lacked TP53 mutations. HPV16 positivity, female patients, non-smokers, and patients with histological grade I and stage N0 diseases showed better overall survival (p = 0.009, 0.003, 0.048, 0.009, and 0.004, respectively). No significant differences in overall survival between smoking and non-smoking patients were observed in the HPV-associated OPSCC group. Patients without mutations in TP53 exons 5–8 had better prognoses (p = 0.031) among the 43 sequenced specimens. Multivariate analysis indicated that HPV16 infection status (p = 0.011), histological grade (p = 0.017), and N stage (p = 0.019) were independent prognostic factors for patients with OPSCC.

Conclusions

Distinct from the situation in Europe and America, for the patients with OPSCC in this study, HPV16 infection was relatively low, although it was still the most important independent prognostic predictor for the disease. In addition to the high smoking and drinking rate in this population, HPV16 infection and TP53 dysfunction appear to be two distinct pathogens for OPSCC patients in the eastern Chinese population.

Transcriptomic characterization of differential gene expression in oral squamous cell carcinoma: a meta-analysis of publicly available microarray data sets

Oral squamous cell carcinoma (OSCC) is a highly prevalent cancer worldwide, and OSCC often goes undiagnosed until advanced disease is present, which contributes to a low survival rate for OSCC patients. The identification of biomarkers for the early detection OSCC and novel therapeutic targets for OSCC treatment is an important research objective. We performed bioinformatics analyses of the gene expression profile of OSCC using microarray data to identify genes that contribute to the development of OSCC. We also predicted the transcription factors involved in the regulation of differential gene expression in OSCC. Our results showed that PI3K, EGFR, STAT1, and CPBP are important contributors to the changes in cellular physiology that occur during the development of OSCC. Therefore, these genes represent potential diagnostic biomarkers and therapeutic targets for OSCC.

Targeted next-generation sequencing of TP53 in oral tongue carcinoma from non-smokers

Background

Little is known regarding the etiology and genomic underpinnings of Oral Tongue Squamous Cell Carcinoma (OTSCC) in patients who lack traditional risk factors, yet the incidence is increasing. In particular, the rate, and role, of TP53 mutations in this cohort has been heavily debated in the literature.

Methods

Tumor DNA from forty-three non-smokers with OTSCC underwent next generation sequencing of TP53.

Results

Sixty percent of samples contained a TP53 mutation. The G > T transversion rate was 5.7 %. TP53 status did not differ by age.

Conclusions

OTSCC in non-smokers have TP53 mutation rates similar to other Head and Neck cancers yet these mutations do not appear related to carcinogen exposure based on the mutational spectrum and clinical history. The mechanisms driving tumorigenesis in this cohort, including mutations in TP53, remain elusive and further studies are needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s40463-016-0160-4) contains supplementary material, which is available to authorized users.

Genetic determinants in head and neck squamous cell carcinoma and their influence on global personalized medicine

While sequencing studies have provided an improved understanding of the genetic landscape of head and neck squamous cell carcinomas (HNSCC), there remains a significant lack of genetic data derived from non-Caucasian cohorts. Additionally, there is wide variation in HNSCC incidence and mortality worldwide both between and within various geographic regions. These epidemiologic differences are in part accounted for by varying exposure to environmental risk factors such as tobacco, alcohol, high risk human papilloma viruses and betel quid. However, inherent genetic factors may also play an important role in this variability. As limited sequencing data is available for many populations, the involvement of unique genetic factors in HNSCC pathogenesis from epidemiologically diverse groups is unknown. Here, we review current knowledge about the epidemiologic, environmental, and genetic variation in HNSCC cohorts globally and discuss future studies necessary to further our understanding of these differences. Long-term, a more complete understanding of the genetic drivers found in diverse HNSCC cohorts may help the development of personalized medicine protocols for patients with rare or complex genetic events.

Similar Squamous Cell Carcinoma Epithelium microRNA Expression in Never Smokers and Ever Smokers

The incidence of oral tumors in patients who never used mutagenic agents such as tobacco is increasing. In an effort to better understand these tumors we studied microRNA (miRNA) expression in tumor epithelium of never tobacco users, tumor epithelium of ever tobacco users, and nonpathological control oral epithelium. A comparison of levels among 372 miRNAs in 12 never tobacco users with oral squamous cell carcinoma (OSCC) versus 10 healthy controls was made using the reverse transcription quantitative polymerase chain reaction. A similar analysis was done with 8 ever tobacco users with OSCC. These comparisons revealed miR-10b-5p, miR-196a-5p, and miR-31-5p as enriched in the tumor epithelium in OSCC of both never and ever tobacco users. Examination of The Cancer Genome Atlas (TCGA) project miRNA data on 305 OSCCs and 30 controls revealed 100% of those miRNAs enriched in never smoker OSCCs in this patient group were also enriched in ever smoker OSCCs. Nonsupervised clustering of TCGA OSCCs was suggestive of two or four subgroups of tumors based on miRNA levels with limited evidence for differences in tobacco exposure among the groups. Results from both patient groups together stress the importance of miR196a-5p in OSCC malignancy in both never and ever smokers, and emphasize the overall similarity of miRNA expression in OSCCs in these two risk groups. It implies that there may be great similarity in etiology of OSCC in never and ever smokers and that classifying OSCC based on tobacco exposure may not be helpful in the clinic.

FHL1 inhibits the growth of tongue squamous cell carcinoma cells via G1/S cell cycle arrest

Four and a half LIM protein 1 (FHL1) has been characterized as a tumor suppressor in various types of tumor. However, the biological function and underlying mechanism of FHL1 in tongue squamous cell carcinoma (TSCC) remain to be elucidated. The present study demonstrated that FHL1 inhibits anchorage‑dependent and ‑independent growth of TSCC cells in vitro and tumor growth in nude mice, as determined by cell proliferation and soft agar assays. Knockdown of FHL1 with FHL1 small interfering RNA (siRNA) promoted tumor growth in nude mice. Mechanistically, flow cytometric analysis showed that knockdown of FHL1 promoted G1/S cell cycle progression. Furthermore, expression of cell cycle‑associated regulators, cyclin D and cyclin E, were detected by western blotting and reverse transcription‑quantitative polymerase chain reaction. Cyclin D and cyclin E were markedly elevated at both the protein and mRNA level in the FHL1 siRNA‑transfected cells. These results suggested that FHL1 has a tumor suppressive role in TSCC and that FHL1 may be a useful target for TSCC gene therapy.