Oral cavity squamous cell carcinoma in never smokers: analysis of clinicopathologic characteristics and survival

Neighborhood Socioeconomic Status and Racial and Ethnic Survival Disparities in Oral Cavity and Laryngeal Cancer

BACKGROUND

Oral cavity cancer (OCC) and laryngeal cancer are among the most common cancers worldwide. This study investigated survival in non-Hispanic (NH) Black, NH White, Asian, and Hispanic patients with OCC and laryngeal cancer of low, intermediate, and high neighborhood socioeconomic status (nSES).

METHODS

We used data from the SEER 18 Census Tract-level SES and Rurality Database of the National Cancer Institute to create cohorts of OCC and laryngeal cancer patients from 2013 to 2018. Univariate survival analysis was performed with Kaplan-Meier curves and log-rank P values by nSES and then the cross-classification of race, ethnicity, and nSES. We used Cox proportional hazards regression model for multivariable analysis.

RESULTS

Higher nSES was associated with better OCC survival for NH White, NH Black, and Asian patients, and better laryngeal cancer survival for NH White, NH Black, Hispanic, and Asian patients. In the multivariable analyses of both OCC and laryngeal cancer survival, NH Black patients had worse survival than NH White patients in the high nSES tertile. NH Black patients with OCC were at higher risk of death than NH White patients at all nSES levels. Conversely, Asian patients with laryngeal cancer demonstrated better survival than other races within the high nSES.

CONCLUSIONS

Overall survival differs between racial and ethnic groups of similar nSESs. These health disparities in patients with OCC and laryngeal cancer reflect broader inequities in the cancer control continuum.

IMPACT

The cross-classification of race, ethnicity, and nSES revealed disparities in the 5-year overall survival of patients with OCC and laryngeal cancer and highlights the importance of intersectionality in the discussion of health equity.

No survival benefit in never-smoker never-drinker patients with oral cavity cancer

BACKGROUND

Although strongly associated with tobacco and alcohol use, many oral cavity squamous cell carcinoma (OCSCC) cases occur in patients without exposure to either, known as "never-smoker, never-drinkers" (NSND). We aimed to compare clinical outcomes between NSND and tobacco/alcohol-exposed populations and to define demographic characteristics of NSND.

METHODS

We performed a retrospective, single-institution cohort study of 672 OCSCC patients. Cox models were used to estimate differences in overall survival (OS) and recurrence-free survival (RFS) between NSND and tobacco/alcohol-exposed patients while adjusting for confounders.

RESULTS

NSND represented 25.6% of our cohort and were older, more female, and more economically advantaged. Among NSND, oral tongue tumors dominated in younger patients, while alveolar ridge tumors dominated in elderly patients. Multivariate survival analysis revealed no differences in OS or RFS between NSND and tobacco/alcohol-exposed patients.

CONCLUSION

When adjusted for independent biologic features, clinical outcomes in OCSCC are similar between NSND and tobacco/alcohol-exposed patients.

Semi-quantitative assessment of environmental tobacco smoke exposure and its association with the development of oral squamous cell carcinoma: A pilot study

INTRODUCTION

Two known major risk factors for oral squamous cell carcinoma are smoking and alcohol consumption. Environmental tobacco smoke (also known as secondhand smoke) has been proven to be associated with the occurrence of lung and breast carcinoma. This study aimed to assess exposure to environmental tobacco smoke and its association with the development of oral squamous cell carcinomas.

METHODS

Using a standardized questionnaire, 165 cases and 167 controls were asked about their demographic data and risk behaviors, including environmental tobacco smoke exposure. An environmental tobacco smoke score (ETS-score) was developed to semi-quantitatively record the previous exposure to ETS. Statistical analyses were performed with χ² test or Fishers exact test, and with ANOVA or Welch's t-test as appropriate. An analysis was done using multiple logistic regression.

RESULTS

Cases had a significantly increased previous exposure to environmental tobacco smoke compared to the controls (ETS-score: 36.69 ± 26.34 vs 13.92 ± 12.44; p<0.0001). Comparing only the groups without additional active risk factors, exposure to environmental tobacco smoke was associated with a more than threefold higher likelihood of oral squamous cell carcinoma (OR=3.47; 95% CI: 1.31-10.55). Statistically significant differences in ETS-score were found for different tumor locations (p=0.0012) and different histopathological gradings (p=0.0399). A multiple logistic regression analysis confirmed exposure to environmental tobacco smoke as an independent risk factor for the development of oral squamous cell carcinomas (p<0.0001).

CONCLUSIONS

Environmental tobacco smoke is an important but yet underestimated risk factor for the development of oral squamous cell carcinomas. Further studies are needed to confirm the results, including the usefulness of the developed environmental tobacco smoke score for exposure.

Repurposing Dihydroartemisinin to Combat Oral Squamous Cell Carcinoma, Associated with Mitochondrial Dysfunction and Oxidative Stress

Oral squamous cell carcinoma (OSCC), with aggressive locoregional invasion, has a high rate of early recurrences and poor prognosis. Dihydroartemisinin (DHA), as a derivative of artemisinin, has been found to exert potent antitumor activity. Recent studies reported that DHA suppresses OSCC cell growth and viability through the regulation of reactive oxygen species (ROS) production and mitochondrial calcium uniporter. However, the mechanism underlying the action of DHA on OSCCs remains elusive. In the study, we observed that 159 genes were remarkably misregulated in primary OSCC tumors associated with DHA-inhibited pathways, supporting that OSCCs are susceptible to DHA treatment. Herein, our study showed that DHA exhibited promising effects to suppress OSCC cell growth and survival, and single-cell colony formation. Interestingly, the combination of DHA and cisplatin (CDDP) significantly reduced the toxicity of CDDP treatment alone on human normal oral cells (NOK). Moreover, DHA remarkably impaired mitochondrial structure and function, and triggered DNA damage and ROS generation, and activation of mitophagy. In addition, DHA induced leakage of cytochrome C and apoptosis-inducing factor (AIF) from mitochondria, elevated Bax/cleaved-caspase 3 expression levels and compromised Bcl2 protein expression. In the OSCC tumor-xenograft mice model, DHA remarkably suppressed tumor growth and induced apoptosis of OSCCs in vivo. Intriguingly, a selective mitophagy inhibitor Mdivi-1 could significantly reinforce the anticancer activity of DHA treatment. DHA and Mdivi-1 can synergistically suppress OSCC cell proliferation and survival. These data uncover a previously unappreciated contribution of the mitochondria-associated pathway to the antitumor activity of DHA on OSCCs. Our study shed light on a new aspect of a DHA-based therapeutic strategy to combat OSCC tumors.

Modifiable risk factors for oral cavity cancer in non-smokers: A systematic review and meta-analysis

BACKGROUND

Oral cavity cancer (OCC) is traditionally associated with smoking, but there is an increasing prevalence of the disease among non-smokers. This review investigates possible modifiable risk factors in the development of OCC in non-smokers (OCCNS).

METHODS

PubMed, EMBASE, Web of Science, and Scopus were searched for publications prior to June 2021. Comparative studies investigating modifiable OCCNS risk factors were identified following PRISMA guidelines. Publication date, population size, and results were indexed. Study quality was assessed using MINORS (Methodological Index for Non-Randomized Studies). Factors examined by multiple studies were analyzed using random-effect meta-analysis framework.

RESULTS

Literature search resulted in 1,625 unique publications. 52 records met inclusion criterion, investigating alcohol (n = 22), chewing products (n = 18), diet (n = 7), dental health (n = 11), and medical comorbidities (n = 6).

CONCLUSION

This review demonstrates the paucity of large studies investigating OCCNS risk factors. Further investigation is warranted to help clinicians risk-stratify patients without traditional risk factors.

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.

Identification of diagnostic and prognostic lncRNA biomarkers in oral squamous carcinoma by integrated analysis and machine learning

BACKGROUND

Patients with oral squamous carcinoma (OSCC) present difficulty in precise diagnosis and poor prognosis.

OBJECTIVE

We aimed to identify the diagnostic and prognostic indicators in OSCC and provide basis for molecular mechanism investigation of OSCC.

METHODS

We collected sequencing data and clinical data from TCGA database and screened the differentially expressed mRNAs (DEmRNAs) and lncRNAs (DElncRNAs) in OSCC. Machine learning and modeling were performed to identify the optimal diagnostic markers. In order to determine lncRNAs with prognostic value, survival analysis was performed through combing the expression profiles with the clinical data. Finally, co-expressed DEmRNAs of lncRNAs were identified by interacted network construction and functional annotated by GO and KEGG analysis.

RESULTS

A total of 1114 (345 up- and 769 down-regulated) DEmRNAs and 156 (86 up- and 70 down-regulated) DElncRNAs were obtained in OSCC. Following the machine learning and modeling, 15 lncRNAs were identified to be the optimal diagnostic indicators of OSCC. Among them, FOXD2.AS1 was significantly associated with survival rate of patients with OSCC. In addition, Focal adhesion and ECM-receptor interaction pathways were found to be involved in OSCC.

CONCLUSIONS

FOXD2.AS1 might be a prognostic marker for OSCC and our study may provide more information to the further study in OSCC.

Effect of smoking status and programmed death-ligand 1 expression on the microenvironment and malignant transformation of oral leukoplakia: A retrospective cohort study

Tobacco smoking is associated with an increased risk of oral leukoplakia and head and neck cancer. Although it has recently been reported that the establishment of an immunosuppressive microenvironment in oral potentially malignant disorders may lead to malignant transformation, it is unclear whether the microenvironments of oral potentially malignant disorders differ according to smoking status. We examined differences in programmed death-ligand 1 (PD-L1) expression and subepithelial CD163+ TAM and CD8+ cell/lymphocyte counts in the microenvironment of oral leukoplakia of smoking and non-smoking patients and investigated their associations with malignant transformation. Pathology reports and original biopsy request forms from 1995–2015 were retrospectively reviewed. Lesions clinically characterized as white plaques/lesions of the oral mucosa and pathologically diagnosed as oral epithelial dysplasia were included. Immunohistochemistry was performed to evaluate PD-L1 expression and subepithelial CD163+/CD8+ cell counts. The significance of prognostic factors in predicting malignant transformation was determined using Cox regression analysis. Statistical significance was defined as P<0.05. In total, 200 patients with oral leukoplakia were selected. The mean age at diagnosis was higher in non-smoking patients (n = 141; 66.9 years) than in smoking patients (n = 59; 60.5 years). The 5-year cumulative malignant transformation rate was higher in non-smoking patients than in smoking patients (9.3% vs. 3.0%, respectively). Oral leukoplakia was associated with significantly higher PD-L1 expression and increased numbers of subepithelial CD163+ cells in the non-smoking group compared with the smoking group. Non-smoking-related oral leukoplakia with positive PD-L1 expression was associated with a 6.97-fold (95% confidence interval: 2.14–22.7) increased risk of malignant transformation. The microenvironment of oral leukoplakia differed according to smoking status. A combination of smoking status and PD-L1 expression may predict malignant transformation in oral leukoplakia patients. This study highlights the importance of understanding the interaction between smoking and the microenvironment in oral leukoplakia.

Silencing of LINC00284 inhibits cell proliferation and migration in oral squamous cell carcinoma by the miR-211-3p/MAFG axis and FUS/KAZN axis

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies worldwide. Emerging evidence has suggested that long noncoding RNAs (lncRNAs) play vital roles in various biological processes of cancers, such as cell proliferation, migration, invasion, and apoptosis. As reported previously, long intergenic non-protein coding RNA 284 (LINC00284) is an important regulator in multiple cancers. However, the biological role, as well as regulatory mechanism of LINC00284 in OSCC, has not been investigated. In our study, RT-qPCR results indicated that LINC00284 was significantly upregulated in OSCC tissues and cells. Moreover, loss-of-function experiments demonstrated that LINC00284 downregulation suppressed cell proliferation and migration and facilitated cell apoptosis. Mechanistically, we found that LINC00284 sponged microRNA 211-3p (miR-211-3p) to upregulate MAF bZIP transcription factor G (MAFG) expression in OSCC cells. Additionally, LINC00284 interacted with FUS protein to increase KAZN mRNA stability. Functional assays showed that either MAFG or KAZN overexpression promoted the malignant behaviors of OSCC cells. Through a series of rescue assays, we found that the inhibitory effect of silencing LINC00284 on OSCC cells can be reversed by upregulated MAFG and KAZN. Overall, silencing LINC00284 inhibits the malignant characteristics of OSCC cells by downregulating MAFG and inhibiting the binding of FUS to KAZN mRNA.

Two novel cell culture models of buccal mucosal oral cancer from patients with no risk-habits of tobacco smoking or chewing

OBJECTIVE

Tobacco consumption is one of the major etiological factors for oral cancer, but it also develops in non-tobacco users, with unknown etiologies. Cellular models for tobacco associated oral cancer are available, however; reports of cellular models for studying non-tobacco associated oral cancer are limiting. We report here the establishment and characterization of two novel buccal mucosal cancer cell lines 'GBC02' and 'GBC035' derived from non-tobacco users.

MATERIALS AND METHODS

Short tandem repeats (STR) profiling, Next-generation sequencing for whole-genome, exome and copy number alterations, immunofluorescence, flow-cytometry, proliferation, live-cell chemotaxis, 3D-spheroid formation, chemotherapy response, gene-expression microarray, gene-set enrichment analysis and xenograft development were performed.

RESULTS

Sources of the established cultures were matched to their donors through STR profiling. Genome sequence analysis revealed somatic mutations in TP53, CASP8, CDKN2A for GBC02 with deletions and amplifications encompassing CDKN2A, FAT1 and CCND1, PIK3CA, SOX2, EGFR, MYC genes, respectively. GBC035 harbored mutations in FAT1, NOTCH1, HRAS, CDKN2A, HLA-B, HLA-A genes. While GBC035 cells showed higher E-Cadherin positive cell-cell junctions and collective cell migration in chemotaxis; GBC02 cells were vimentin-positive and demonstrated individual cell migration. Further, exhibiting their relevance to preclinical research, GBC02 3D-spheroids demonstrated enrichment of development-related gene-signatures in microarray transcriptome analysis and were resistant to Cisplatin, but showed sensitivity to cancer stem cells-targeting drug, Salinomycin. Additionally, tumorigenic ability of GBC02 was demonstrated.

CONCLUSIONS

Altogether, we present here comprehensively characterized unique cell lines established from non-tobacco associated tumors, which may serve as models for preclinical investigations of oral cancers caused independent of tobacco usage.

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.

Clinico-pathological significance of Drp1 dysregulation and its correlation to apoptosis in oral cancer patients

Dysregulation in mitochondrial dynamics has been associated with several diseases including cancer. Present study assessed the alteration in mitochondrial fission protein (Drp1) in oral epithelial cells collected from clinically confirmed pre-cancer and cancer patients and further correlates it with the cellular apoptosis signaling. Results indicate the ROS accumulation in OSCC patients is accompanied by several changes including increase in mitochondrial mass, expression of mitochondrial fission protein (Drp1) and alteration in apoptotic signaling. The positive co-relation has been observed between the expressions of anti-apoptotic Bcl-2proteinswith mitochondrial fission protein Drp1. Higher mitochondrial fission in oral cancer cells was also correlated with the increased expression of cell cycle marker CyclinD1 indicating highly proliferative stage of oral cancer cells. The clinical correlation can be extended to develop biomarker for diagram and program in oral cancer management.

Computer-assisted image analysis of the tumor microenvironment on an oral tongue squamous cell carcinoma tissue microarray

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Tissue segmentation can be achieved using a spatially registered cytokeratin mask.

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Automated and manual cell counts and stain intensities were highly correlated.

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Smokers had significantly stronger PD-L1 stain intensity and higher numbers TILs.

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After radiotherapy, greater CD8+ TILs was associated with inferior survival.

Oral tongue squamous cell carcinoma (OTSCC) displays variable levels of immune cells within the tumor microenvironment. The quantity and localization of tumor infiltrating lymphocytes (TILs), specific functional TIL subsets (e.g., CD8+), and biomarker-expressing cells (e.g., PD-L1+) may have prognostic and predictive value. The purpose of this study was to evaluate the robustness and utility of computer-assisted image analysis tools to quantify and localize immunohistochemistry-based biomarkers within the tumor microenvironment on a tissue microarray (TMA). We stained a 91-patient OTSCC TMA with antibodies targeting CD3, CD4, CD8, FOXP3, IDO, and PD-L1. Cell populations were segmented into epithelial (tumor) or stromal compartments according to a mask derived from a pan-cytokeratin stain. Definiens Tissue Studio was used to enumerate marker-positive cells or to quantify the staining intensity. Automated methods were validated against manual tissue segmentation, cell count, and stain intensity quantification. Univariate associations of cell count and stain intensity with smoking status, stage, overall survival (OS), and disease-free survival (DFS) were determined. Our results revealed that the accuracy of automated tissue segmentation was dependent on the distance of the tissue section from the cytokeratin mask and the proportion of the tissue containing tumor vs. stroma. Automated and manual cell counts and stain intensities were highly correlated (Pearson coefficient range: 0.46–0.90; p < 0.001). Within this OTSCC cohort, smokers had significantly stronger PD-L1 stain intensity and higher numbers of CD3+, CD4+ and FOXP3+ TILs. In the subset of patients who had received adjuvant radiotherapy, a higher number of CD8+ TILs was associated with inferior OS and DFS. Taken together, this proof-of-principle study demonstrates the robustness and utility of computer-assisted image analysis for high-throughput assessment of multiple IHC markers on TMAs, with potential implications for studies on prognostic and predictive biomarkers.

LncRNA-p23154 promotes the invasion-metastasis potential of oral squamous cell carcinoma by regulating Glut1-mediated glycolysis

The dysregulation of glycolysis has been suggested to lead to alteration of cell drug resistance signals, proliferation and metastasis. Emerging evidence indicates that lncRNAs play a key role in the cellular processes of tumor cells, including glycolysis, growth, and movement. However, the role and potential mechanism of lncRNAs in glycolysis-mediated metastasis has not been explored. In this study, we identified a novel lncRNA lnc-p23154 which is associated with OSCC patient metastasis and the promotion of OSCC cell migration and invasion in vitro and in vivo. Furthermore, we found that lnc-p23154 also participates in OSCC glycolysis by facilitating Glut1 expression. Rescue of lnc-p23154 reversed the suppression of OSCC cell migration and invasion induced by Glut1 knockdown. In addition, lnc-p23154 is mainly located in the nucleus and binds to the promoter region of miR-378a-3p, which represses Glut1 expression by targeting to its 3'UTR directly. Therefore, we concluded that lnc-p23154 may play an important role in Glut1-mediated glycolysis by inhibiting miR-378a-3p transcription and accelerate OSCC metastasis.

Characterization of epithelial oral dysplasia in non-smokers: First steps towards precision medicine

OBJECTIVES

Tobacco usage is the strongest risk factor in the development of oral squamous cell carcinoma (OSCC), which mandates careful screening for oral cancers in smokers. However, there are indications that oral potentially malignant lesions, such as oral epithelial dysplasia (OED), in non-smokers (NS) have a higher cancer risk than those in smokers. Without tobacco as an etiology, the development of these lesions in NS may suggest genetic susceptibility. The increasing incidence of OSCC in NS calls for a better understanding of the natural history of OED in NS as compared to that of smokers.

MATERIALS AND METHODS

Patients from a population-based longitudinal study with more than 10 years of follow up were analyzed. Of the 455 patients with primary OED (233 mild and 212 moderate dysplasia), 139 were NS and 306 were smokers. Demographic and habit information, clinical information (lesion site, size and appearance; toluidine blue and fluorescent visualization), microsatellite analysis for loss of heterozygosity (LOH) and outcome (progression) were compared between the two groups.

RESULTS AND CONCLUSIONS

The majority of patients with OED were smokers. Of these, more were males, non-Caucasians and heavy drinkers. A significantly higher number of OED in NS were in the tongue, whereas a significantly higher number of OED in smokers were in the floor of mouth (FOM). OED in NS showed a greater than 2-fold increase in cancer progression. Strikingly, OED located in the FOM in NS showed a 38-fold increase in cancer progression as compared to those in smokers.

Clinical Outcomes in pT4 Tongue Carcinoma are Worse than in pT3 Disease: How Extrinsic Muscle Invasion Should be Considered?

BACKGROUND

The identification of extrinsic tongue muscle invasion in oral cavity cancer remains challenging. Notably, the most recent American Joint Committee on Cancer (AJCC 2017, 8th edition) staging manual indicates that extrinsic muscle invasion does not lead to the diagnosis of a T4 tumor. Because this approach carries the risk of tumor downstaging, we compared the clinical outcomes of patients with oral tongue squamous cell carcinoma (SCC) staged as pT3 vs. pT4 according to the AJCC 2010, 7th edition criteria.

METHODS

We retrospectively examined the records of consecutive patients with pT3 (n = 135) and pT4 (n = 68) tongue SCC who underwent radical surgery. Of the 68 pT4 tongue SCC, 63 (93%) had extrinsic muscle involvement alone. The 5-year locoregional control (LRC), distant metastasis (DM), and disease-free survival (DFS) rates served as outcome measures.

RESULTS

Compared with pT3 tongue SCC, pT4 patients presented significantly more frequently with pN2 disease, extranodal extension, poor tumor differentiation, tumor depth >15 and >20 mm, margin status ≤4 mm, perineural invasion, vascular invasion, and were more frequently treated with surgery plus concurrent chemoradiotherapy. Less favorable 5-year outcomes were observed in patients with pT4 than pT3 tumors (LRC 50 vs. 75%, p < 0.001; DM 27 vs. 14%, p = 0.013; DFS 43 vs. 69%, respectively, p < 0.001). We identified pT4 disease (vs. pT3) as an independent adverse prognostic factor for LRC and DFS.

CONCLUSIONS

We suggest classifying patients with tongue SCC and extrinsic muscle invasion as having pT4 disease.

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.

Dichloroacetate, a selective mitochondria-targeting drug for oral squamous cell carcinoma: a metabolic perspective of treatment

Reprogramming of metabolism is a well-established property of cancer cells that is receiving growing attention as potential therapeutic target. Oral squamous cell carcinomas (OSCC) are aggressive and drugs-resistant human tumours displaying wide metabolic heterogeneity depending on their malignant genotype and stage of development. Dichloroacetate (DCA) is a specific inhibitor of the PDH-regulator PDK proved to foster mitochondrial oxidation of pyruvate. In this study we tested comparatively the effects of DCA on three different OSCC-derived cell lines, HSC-2, HSC-3, PE15. Characterization of the three cell lines unveiled for HSC-2 and HSC-3 a glycolysis-reliant metabolism whereas PE15 accomplished an efficient mitochondrial oxidative phosphorylation. DCA treatment of the three OSCC cell lines, at pharmacological concentrations, resulted in stimulation of the respiratory activity and caused a remarkably distinctive pro-apoptotic/cytostatic effect on HSC-2 and HSC-3. This was accompanied with a large remodeling of the mitochondrial network, never documented before, leading to organelle fragmentation and with enhanced production of reactive oxygen species. The data here presented indicate that the therapeutic efficacy of DCA may depend on the specific metabolic profile adopted by the cancer cells with those exhibiting a deficient mitochondrial oxidative phosphorylation resulting more sensitive to the drug treatment.

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.

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

OBJECTIVES/HYPOTHESIS

To determine the incidence and clinical significance of TP53 and CDKN2a somatic mutations in never smokers with oral tongue squamous cell carcinoma (OTSCC).

STUDY DESIGN

Case series.

METHODS

Fifty-one paraffin-embedded tumors from never smokers with OTSCC were obtained. p53 and p16 expression was determined by immunohistochemical (IHC) staining. Tumor DNA was amplified by polymerase chain reaction, and direct sequencing and mutation analysis was performed. Statistical relationships among p53 and p16 IHC findings, TP53 and CDKN2a mutation status, and clinicopathologic characteristics were determined. Univariate and multivariate Cox models for survival were performed.

RESULTS

Sixteen tumors (31.4%) showed strong expression of p53 by IHC. There was no correlation between p53 status and clinicopathologic variables or survival outcomes. TP53 mutations were seen in 10 tumors (19.6%). Patients with TP53 mutations had higher tumor-node-metastasis (TNM) stage (P=0.049), worse tumor differentiation (P=0.025), earlier recurrence (P=0.024), and more often died from their disease (P=0.043) than those without mutations. Five tumors (9.8%) showed p16 positivity by IHC. There was no correlation between p16 status and clinicopathologic variables or survival. CDKN2a mutations were seen in four tumors (7.8%). Patients with CDKN2a mutations had earlier recurrence (P=0.019) and more often died from their disease (P=0.010) than those without mutations. Kaplan-Meier curves show worse disease-free survival (P=0.0162, P=0.0025) and overall survival (P=0.0095, P=0.0001) for TP53 and CDKN2a mutations, respectively. Multivariate analysis demonstrated that TP53 and CDKN2a mutations were independent predictors of disease-free survival (P=0.038 and P=0.039, respectively).

CONCLUSIONS

TP53 and CDKN2a mutations in never-smoker OTSCC are associated with worse clinicopathologic characteristics and poorer survival outcomes.

LEVEL OF EVIDENCE

N/A.