Association between human papillomavirus and oral cancer: a literature review

HPV plays a vital role in the development of cervical cancers and oropharyngeal cancers, but it is controversial whether HPV is involved in oral cancer development and to what extent. In this review, the clinical characteristics, diagnosis, treatment, and prognosis of HPV-positive oral cancers are summarized, and the mechanisms of HPV-related oral cancer development are discussed. HPV DNA positivity rates are 20-30% in oral squamous cell carcinoma (OSCC), and HPV16 is the most common high-risk HPV. E6/E7 mRNA positivity rates are 2-6% in OSCC. Detection of both high-risk HPV DNA and E6/E7 mRNA is recommended to determine the presence of active HPV, in agreement with high-risk HPV infection in OSCC. Surgical treatment is the first-line therapy for HPV-positive and -negative oral cancer, but there is no unified view about the prognosis of HPV-positive OSCC patients. HPV16 may play a vital role in malignant transformation in oral epithelial dysplasia, and a model of synergistic carcinogenic impact of HPV and tobacco smoking is predicted. Additionally, it is hypothesized that there are different HPV-associated oral cancers, such as integrated HPV DNA-positive OSCC with stable E6/E7 expression and episomal HPV DNA-positive OSCC. In summary, the role of HPV in oral carcinogenesis seems to be limited because of the low E6/E7 positivity in OSCCs; however, episomal HPV DNA may play a vital role in the malignant transformation of HPV-positive oral premalignant lesions. Further investigation is required to promote new insights into the role of episomal HPV DNA in oral carcinogenesis.

Fibroblast growth factor (FGF), FGF receptor (FGFR), and cyclin D1 (CCND1) DNA methylation in head and neck squamous cell carcinomas is associated with transcriptional activity, gene amplification, human papillomavirus (HPV) status, and sensitivity to tyrosine kinase inhibitors

Background

Dysregulation of fibroblast growth factor receptor (FGFR) signaling pathway has been observed in head and neck squamous cell carcinoma (HNSCC) and is a promising therapeutic target for selective tyrosine kinase inhibitors (TKIs). Potential predictive biomarkers for response to FGFR-targeted therapies are urgently needed. Understanding the epigenetic regulation of FGF pathway related genes, i.e. FGFRs, FGFs, and CCND1, could enlighten the way towards biomarker-selected FGFR-targeted therapies.

Methods

We performed DNA methylation analysis of the encoding genes FGFR1, FGFR2, FGFR3, FGFR4, FGF1-14, FGF16-23, and CCND1 at single CpG site resolution (840 CpG sites) employing The Cancer Genome Research Atlas (TCGA) HNSCC cohort comprising N = 530 tumor tissue and N = 50 normal adjacent tissue samples. We correlated DNA methylation to mRNA expression with regard to human papilloma virus (HPV) and gene amplification status. Moreover, we investigated the correlation of methylation with sensitivity to the selective FGFR inhibitors PD 173074 and AZD4547 in N = 40 HPV(−) HNSCC cell lines.

Results

We found sequence-contextually nuanced CpG methylation patterns in concordance with epigenetically regulated genes. High methylation levels were predominantly found in the promoter flank and gene body region, while low methylation levels were present in the central promoter region for most of the analyzed CpG sites. FGFRs, FGFs, and CCND1 methylation differed significantly between tumor and normal adjacent tissue and was associated with HPV and gene amplification status. CCND1 promoter methylation correlated with CCND1 amplification. For most of the analyzed CpG sites, methylation levels correlated to mRNA expression in tumor tissue. Furthermore, we found significant correlations of DNA methylation of specific CpG sites with response to the FGFR1/3–selective inhibitors PD 173074 and AZD4547, predominantly within the transcription start site of CCND1.

Conclusions

Our results suggest an epigenetic regulation of CCND1, FGFRs, and FGFs via DNA methylation in HNSCC and warrants further investigation of DNA methylation as a potential predictive biomarker for response to selective FGFR inhibitors in clinical trials.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01212-4.

Genetic and methylation status of CDKN2A (p14ARF/p16INK4A) and TP53 genes in recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis (RRP) is a rare and chronic disease affecting the upper airway with papillomatous lesions caused by the human papillomavirus (HPV) infection, especially HPV-6 and/or HPV-11 types. Little is known about the genetic and epigenetic drivers in RRP pathophysiology. For this purpose, we analyzed 27 papillomatous lesions from patients with RRP to evaluate somatic mutations and methylation status in CDKN2A (p14^ARF/p16^INK4A) and TP53, which are key tumor suppressor genes for the cell cycle control. Sanger sequencing analysis revealed one somatic mutation in TP53 (c.733_734insA) and four mutations in CDKN2A (c.-30G > T, c.29_30insA, c.69delT, and c.300C > A). These mutations were observed in 10 patients, 6 of which carried double mutation. Furthermore, 50% (5/10) of these patients carrying somatic mutations had RRP severity, representing 62.5% (5/8) of the severity cases in this study, albeit no significant association was found between somatic mutations and disease severity. Methylation-specific polymerase chain reaction assays revealed p14^ARF promoter hypermethylation in 100% of cases, followed by TP53 (96.3%) and p16^INK4A (55.6%), suggesting the influence of HPV in the DNA methylation machinery. In conclusion, somatic mutations were not common events identified in patients with RRP. However, epigenetic modulation by high methylation rates, particularly for the p14^ARF/TP53 pathway, seems to be in the course of RRP development.

Evaluation of HPV and EBV in OSCC and the expression of p53, p16, E-cadherin, COX-2, MYC, and MLH1

OBJECTIVE

This study aimed to evaluate the presence of human papillomavirus (HPV) and Epstein-Barr virus (EBV) and the expression of p53, p16, E-cadherin, COX-2, MLH1, and MYC in oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

One hundred OSCC specimens were submitted to in situ hybridization for HPV and EBV, and immunohistochemistry for detection of the human proteins.

RESULTS

Thirty-one cases showed HPV in tumor tissue. EBV was not detected in any case investigated. The HPV(+) group demonstrated an increase of staining scores for nuclear p16 (p = .047), cytoplasmic MYC (p = .002), while a decrease for nuclear MLH1 (p = .048), suggesting that HPV may upregulate the expression of the first two proteins and down-regulate the latter.

CONCLUSION

Our findings reinforce the hypothesis of the HPV-related oral carcinogenesis involving the expression of p16 and MYC, and MLH1 suppression. Exclusively cytoplasmic stainings for p16, MLH1, and MYC were also associated with more advanced tumors. Finally, in view of the lack of studies correlating the HPV or EBV infection to the expression of oncoproteins, more researches assessing a broader panel of markers and employing different approaches are still necessary in order to understand the role of these viruses as well as the molecular mechanisms involved in the development and progression of oral carcinomas.

Improved local control in p16 negative oropharyngeal cancers with hypermethylated MGMT

INTRODUCTION

Patients with oropharyngeal cancers that are p16 negative (p16-) have worse outcomes than those who are p16 positive (p16+) and there is an unmet need for prognostic markers in this population. O6-Methylguanine (O6-MG)-DNA-methyltransferase (MGMT) gene methylation has been associated with response to chemoradiotherapy (CRT) in glioblastoma. We sought to find if MGMT promoter methylation was associated with outcomes of locally advanced oropharyngeal and oral cavity squamous cell carcinoma (OOSCC) in patients treated with definitive concurrent CRT.

METHODS

Patients were identified with primary OOSCC, known p16 status, retrievable pre-treatment biopsies, and at least 6 months of follow-up who received definitive concurrent CRT from 2004 to 2015. Biopsies were tested for MGMT hypermethylation (MGMT+) using a Qiagen pyrosequencing kit (Catalog number 970061). Outcomes were subsequently recorded and analyzed.

RESULTS

Fifty-eight patients were included with a median follow up of 78 (range 6-196) months. Fourteen patients (24.1%) had oral cavity cancer and 44 (75.9%) had oropharyngeal cancer. A significant difference was found for local recurrence free survival (LRFS) by combined MGMT and p16 status (p = 0.0004). Frequency of LR in MGMT+/p16+, MGMT+/p16-, MGMT-/p16+, and MGMT-p16- patients was 14.3%, 14.3%, 13.0%, and 69.2%, respectively (p = 0.0019). A significant difference was not found for distant recurrence free survival (p = 0.6165) or overall survival (p = 0.1615). LRFS remained significant on analysis restricted to oropharyngeal cancer patients (p-value = 0.0038).

CONCLUSION

Patients who are p16- and MGMT+ with oropharyngeal and oral cavity squamous cell carcinoma have significantly better LC with definitive CRT than those who are p16- and MGMT-. Prospective studies are needed to verify these findings.

Active HPV infection and its influence on survival in head and neck squamous-cell cancer

Purpose

HPV is involved in the development of some head and neck squamous-cell carcinomas (HNSCC). It was suggested that only transcriptionally active virus can induce carcinogenesis, therefore, the aim of our study was to analyze the frequency of active HPV infection, virus type, and its prognostic role in HNSCC patients.

Methods

Status of active HPV infection was assessed for 155 HNSCC patients based on p16 expression and HPV DNA presence. Univariate and multivariate analyses with Cox proportional regression model were performed to select independent prognostic factors.

Results

Active HPV infection was detected in 20.65% of patients. We identified 16.0, 40.9 and 1.7% of HPV positive oral cavity, oropharyngeal, and laryngeal cancer cases, respectively. HPV16 was dominant (81.25%) followed by HPV35 (9.38%) and double infections with HPV16 and 35 (6.25%) or HPV35 and 18 (3.12%). Patients with active HPV infection demonstrated significantly higher survival than HPV negative ones (OS 80.89% vs. 37.08%, p = 0.000; DFS 93.0% vs. 53.35%, p = 0.000, respectively). Longer OS and DFS were maintained for infected patients when oropharyngeal and non-oropharyngeal cases were analyzed separately. Interestingly, all patients infected with other than HPV16 types survived 5 years without cancer progression. In the analyzed group of 155 patients the strongest independent favourable prognostic factor for both OS and DFS was HPV presence.

Conclusions

High prevalence of HPV-driven HNSCC (mostly within oropharynx) was detected, with HPV16 type the most frequent, followed by HPV35 and HPV18. The presence of active HPV infection improved survival of both oropharyngeal and non-oropharyngeal cancer patients and should be taken into account in treatment planning.

Altered DNA methylation is associated with aberrant stemness gene expression in early‑stage HNSCC

Head and neck squamous cell carcinoma (HNSCC) is characterized by morphological and functional cellular heterogeneity, which are properties of progenitor cells, as opposed to cell alterations caused by accidental expression of stem cell‑related molecules. The expression levels of stemness molecules and their distribution in HNSCC are unclear. As regards sporadic cellular heterogeneity, methylation is an important factor for transcriptional regulation in tumors. Integrative screening analysis of mRNA expression and altered methylation status was performed with original microarrays in 12 tumor and non‑tumor pairs of oral squamous cell carcinoma (SCC) cases. From this data set, genes regulated via aberrant DNA methylation and classified proteins were validated by function clustering. Olfactomedin 4 (OLFM4), known as an intestinal stemness molecule and cell‑cell adhesion factor, was found to be highly expressed in tumors, with an mRNA expression ratio [tumor/normal (T/N)] of 40.7686 and low methylation (‑18.02%) in the promoter region. In addition, the OLFM4 expression levels increased following treatment with the demethylating agent 5‑azacytidine in two HNSCC cell lines. Furthermore, the expression levels of OLFM4 in 59 cases of early‑stage tongue SCC were analyzed using immunohistochemistry to examine protein expression corresponding to the histopathological definition of tumors and to evaluate prognosis. The aberrant stemness gene expression caused by altered DNA methylation appeared to regulate early‑stage HNSCC characteristics. The results of the present study indicated a correlation between OLFM4 expression and promoter methylation, and suggest that it plays an important role in tumor cell heterogeneity in HNSCC.

Molecular prognosticators in clinically and pathologically distinct cohorts of head and neck squamous cell carcinoma-A meta-analysis approach

Head and neck squamous cell carcinomas (HNSCC) includes multiple subsites that exhibit differential treatment outcome, which is in turn reflective of tumor stage/histopathology and molecular profile. This study hypothesized that the molecular profile is an accurate prognostic adjunct in patients triaged based on clinico-pathological characteristics. Towards this effect, publically available micro-array datasets (n = 8), were downloaded, classified based on HPV association (n = 83) and site (tongue n = 88; laryngopharynx n = 53; oropharynx n = 51) and re-analyzed (Genespring; v13.1). The significant genes were validated in respective cohorts in The Cancer Genome Atlas (TCGA) for correlation with clinico-pathological parameters/survival. The gene entities (n = 3258) identified from HPV based analysis, when validated in TCGA identified the subset specifically altered in HPV+ HNSCC (n = 63), with three genes showing survival impact (RPP25, NUDCD2, NOVA1). Site-specific meta-analysis identified respective differentials (tongue: 3508, laryngopharynx: 4893, oropharynx: 2386); validation in TCGA revealed markers with high incidence (altered in >10% of patients) in tongue (n = 331), laryngopharynx (n = 701) and oropharynx (n = 404). Assessment of these genes in clinical sub-cohorts of TCGA indicated that early stage tongue (MTFR1, C8ORF33, OTUD6B) and laryngeal cancers (TWISTNB, KLHL13 and UBE2Q1) were defined by distinct prognosticators. Similarly, correlation with perineural/angiolymophatic invasion, identified discrete marker panels with survival impact (tongue: NUDCD1, PRKC1; laryngopharynx: SLC4A1AP, PIK3CA, AP2M1). Alterations in ANO1, NUDCD1, PIK3CA defined survival in tongue cancer patients with nodal metastasis (node+ECS-), while EPS8 is a significant differential in node+ECS- laryngopharyngeal cancers. In oropharynx, wherein HPV is a major etiological factor, distinct prognosticators were identified in HPV+ (ECHDC2, HERC5, GGT6) and HPV- (GRB10, EMILIN1, FNDC1). Meta-analysis in combination with TCGA validation carried out in this study emphasized on the molecular heterogeneity inherent within HNSCC; the feasibility of leveraging this information for improving prognostic efficacy is also established. Subject to large scale clinical validation, the marker panel identified in this study can prove to be valuable prognostic adjuncts.