Human Papillomavirus 16 and 18 Infection in Oral Cancer in Thailand: A Multicenter Study

The Significance of Modified Histone H3 in Epithelial Dysplasia and Oral Cancer

BACKGROUND

Oral carcinogenesis is complex and influenced by both genetic and epigenetic changes. Altered histone modification is the epigenetic event that plays a role in cancer development and progression. Distinct modification patterns of histones have been shown to affect patient prognosis in selected cancers. This study aimed to evaluate the profiles of histone H3 modification in oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC) in association with the clinical-pathologic characteristics.

METHODS

One hundred patients were divided into 4 groups: low-grade OED, high-grade OED, OSCC, and normal oral mucosa (NOM). The levels of 3 types of histone modification-the H3K18ac, H3K9me3, and H3K9ac-were analysed immunohistochemically. Their expression profiles were compared and correlated with prognostically relevant clinical and pathologic features.

RESULTS

The H3K18ac and H3K9me3 were upregulated in OSCC, compared with OED and NOM. In contrast, the H3K9ac was downregulated in low-grade OED but increased in high-grade OED and OSCC. The hyperacetylations of H3K18 and H3K9 significantly correlated with advanced cancer depth of invasion and high T stage, respectively.

CONCLUSIONS

Histone H3 acetylation and methylation at lysine residues are differentially involved in the multistep oral carcinogenesis and impact aggressive cancer phenotypes. The effect of H3K9ac appears early in OED development, whilst the increased H3K18ac and H3K9me3 may be vital in the emergence of OSCC.

Prevalence of high-risk human papillomavirus in oral squamous cell carcinoma with or without chewing habits

Oral cancer (OC) is the most common cancer in Pakistani males and the second most common in females. Major risk factors include peculiar chewing habits, human papillomavirus (HPV) infection and molecular pathways. However, less data is available for this avertible cancer regarding its association with high-risk HPV (HR-HPV) and chewing habits in this region. Therefore, this study was done to determine the prevalence of HR-HPV in oral squamous cell carcinoma (OSCC) and its correlation with p16 and chewing habits. Formalin-fixed paraffin-embedded (FFPE) biopsy specimens of 186 samples were tested for HR-HPV type 16/18 by PCR, followed by p16 immunostaining (IHC) in a subset of cases (n = 50). Appropriate statistical tests were applied to find the association between HR-HPV/p16 and peculiar chewing habits with significance criteria of p<0.05 with 95% CI. HR-HPV (type 16 &18) was present in seven out of 186 cases (3.8%). Of these seven cases, five were positive for HPV16, whereas two were positive for HPV16/18. The overall expression of p16 protein in 50 samples was 38% (n = 19), and among these 19-IHC positive samples, 26% were positive for HR-HPV DNA. No significant association was found between HR-HPV positivity and p16 and chewing habits (p>0.05). It was concluded that HR-HPV prevalence in OSCC was very low in our population, with no statistically significant correlation with p16 and chewing habits. These results suggest the role of HR-HPV as an independent risk factor in OSCC in the local setting.

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.

The Prevalence of HPV in Oral Cavity Squamous Cell Carcinoma

Human papillomavirus (HPV) is an important risk factor in a subset of head and neck squamous cell carcinomas (HNSCC), but the association with oral cavity squamous cell carcinomas (OCSCC) remains controversial. This study aimed to identify the prevalence of HPV infection in OCSCC. A systematic search on PubMed and EMBASE was performed, including articles assessing the prevalence of HPV-positive (HPV+) OCSCC published from January 2017 to December 2022. OCSCC was considered HPV+ by the detection of HPV DNA, HPV RNA, and/or p16 overexpression in the tumor mass. A meta-analysis was made determining the overall HPV+ OCSCC prevalence. We included 31 studies comprising 5007 patients from 24 countries. The study size ranged from 17 to 940 patients. The HPV+ OCSCC proportion variated widely and ranged from 0% to 37%. Tumors in the tongue were the predominant sublocation for HPV in the oral cavity. The meta-analysis revealed that the overall HPV+ OCSCC prevalence is 6% (95% CI; 3-10%), and only one study found HPV and OCSCC significantly associated. Thus, HPV may not be a necessary or a strong risk factor in OCSCC oncogenesis, and the possibility of a site misclassification of a mobile tongue with the root of the tongue cannot be excluded.

Expression of PD-L1 is HPV/P16-independent in oral squamous cell carcinoma

Objectives

Study design

Results

Conclusion

Detection of Human Papillomavirus and p16INK4a Expression in Thai Patients with Oral Squamous Cell Carcinoma

This study investigated the prevalence of human papillomavirus (HPV) infection in oral squamous cell carcinoma (OSCC) cases, as well as the association between HPV presence and p16^INK4a expression, in Thai patients with OSCC. Eighty-one formalin-fixed paraffin-embedded specimens of OSCC were obtained. DNA extraction was performed; this was followed by nested polymerase chain reaction analysis to determine HPV DNA status, using consensus primers for the L1 region of HPV. HPV subtypes were determined by DNA sequencing. HPV-positive specimens and HPV-negative specimens from age- and sex-matched patients were subjected to immunohistochemical analysis to determine p16^INK4a expression status. Of the 81 OSCC specimens, eight (9.9%) exhibited HPV DNA; DNA sequencing confirmed that the viral subtype was HPV-18 in all eight specimens. These eight HPV-positive specimens, as well as eight HPV-negative specimens from age- and sex-matched patients, were subjected to immunohistochemical analysis to determine p16^INK4a expression status. Three of eight (37.8%) HPV-positive specimens and three of eight (37.8%) HPV-negative specimens showed positive p16^INK4a expression findings. However, we did not find a significant association between HPV status and p16^INK4a expression status in our OSCC samples. In conclusion, the prevalence of high-risk HPV was low in this group of OSCC patients; no association between HPV status and p16^INK4a expression status was identified.