Expression of estrogen receptor alpha is associated with pathogenesis and prognosis of human papillomavirus-positive oropharyngeal cancer

Fibroblast Stromal Support Model for Predicting Human Papillomavirus-Associated Cancer Drug Responses

Currently, there are no specific antiviral therapeutic approaches targeting Human papillomaviruses (HPVs), which cause around 5% of all human cancers. Specific antiviral reagents are particularly needed for HPV-related oropharyngeal cancers (HPV+OPCs) whose incidence is increasing and for which there are no early diagnostic tools available. We and others have demonstrated that the estrogen receptor alpha (ERα) is overexpressed in HPV+OPCs, compared to HPV-negative cancers in this region, and that these elevated levels are associated with an improved disease outcome. Utilizing this HPV+ specific overexpression profile, we previously demonstrated that estrogen attenuates the growth and cell viability of HPV+ keratinocytes and HPV+ cancer cells in vitro. Expansion of this work in vivo failed to replicate this sensitization. The role of stromal support from the tumor microenvironment (TME) has previously been tied to both the HPV lifecycle and in vivo therapeutic responses. Our investigations revealed that in vitro co-culture with fibroblasts attenuated HPV+ specific estrogen growth responses. Continuing to monopolize on the HPV+ specific overexpression of ERα, our co-culture models then assessed the suitability of the selective estrogen receptor modulators (SERMs), raloxifene and tamoxifen, and showed growth attenuation in a variety of our models to one or both of these drugs in vitro. Utilization of these SERMs in vivo closely resembled the sensitization predicted by our co-culture models. Therefore, the in vitro fibroblast co-culture model better predicts in vivo responses. We propose that utilization of our co-culture in vitro model can accelerate cancer therapeutic drug discovery.

Peritumoral SPARC expression induced by exosomes from nasopharyngeal carcinoma infected Epstein-Barr virus: A poor prognostic marker

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) cells have high metastatic potential. Recent research has revealed that the interaction of between tumor cells and the surrounding stroma plays an important role in tumor invasion and metastasis. In this study, we showed the prognostic value of expression of SPARC, an extracellular matrix protein with multiple cellular functions, in normal adjacent tissues (NAT) surrounding NPC. In the immunohistochemical analysis of 51 NPC biopsy specimens, SPARC expression levels were significantly elevated in the NAT of EBER (EBV-encoded small RNA)-positive NPC compared to that in the NAT of EBER-negative NPC. Moreover, increased SPARC expression in NAT was associated with a worsening of overall survival. The enrichment analysis of RNA-seq of publicly available NPC and NAT surrounding NPC data showed that high SPARC expression in NPC was associated with epithelial mesenchymal transition promotion, and there was a dynamic change in the gene expression profile associated with interference of cellular proliferation in NAT, including SPARC expression. Furthermore, EBV-positive NPC cells induce SPARC expression in normal nasopharyngeal cells via exosomes. Induction of SPARC in cancer-surrounding NAT cells reduced intercellular adhesion in normal nasopharyngeal structures and promoted cell competition between cancer cells and normal epithelial cells. These results suggest that epithelial cells loosen their own binding with the extracellular matrix as well as stromal cells, facilitating the invasion of tumor cells into the adjacent stroma by activating cell competition. Our findings reveal a new mechanism by which EBV creates a pro-metastatic microenvironment by upregulating SPARC expression in NPC.

From Infection to Malignancy: Tracing the Impact of Human Papillomavirus on Uterine Endometrial Cancer in a Nationwide Population-Based Cohort Study

Uterine endometrial cancer (EC) is the most common gynecological malignancy in Taiwan. This study aimed to investigate the association between human papillomavirus (HPV) infection and the development of uterine EC among Taiwanese women. A nationwide population cohort research approach was employed, leveraging longitudinal health insurance databases (LHID 2007 and 2015) from the National Health Insurance Research Database alongside data from the Taiwan Cancer Registry datasets. A comparative analysis examined 472,420 female patients with HPV infection and 944,840 without HPV infection. The results demonstrated that the HPV cohort exhibited a significantly elevated risk of uterine EC, as evidenced by an adjusted hazard ratio (aHR) of 1.588 (95% CI: 1.335-1.888). Furthermore, this elevated risk extended to type 1 EC with an aHR of 1.671 (95% CI: 1.376-2.029), specifically the endometrioid adenocarcinoma subtype with an aHR 1.686 (95% CI: 1.377-2.065). Importantly, these findings were statistically significant (p < 0.001). In conclusion, this research unveils a potential association between HPV infection and an increased risk of uterine EC, particularly the type 1 endometrial cancer subtype, within the Taiwanese female population. These findings have implications for preventive measures and screening programs targeting HPV infection to reduce the risk of this prevalent gynecological malignancy in Taiwan.

Estrogen induces the expression of EBV lytic protein ZEBRA, a marker of poor prognosis in nasopharyngeal carcinoma

Several epidemiological studies have suggested that Epstein-Barr virus (EBV) lytic infection is essential for the development of nasopharyngeal carcinoma (NPC), as elevation of antibody titers against EBV lytic proteins is a common feature of NPC. Although ZEBRA protein is a key trigger for the initiation of lytic infection, whether its expression affects the prognosis and pathogenesis of NPC remains unclear. In this study, 64 NPC biopsy specimens were analyzed using immunohistochemistry. We found that ZEBRA was significantly associated with a worsening of progression-free survival in NPC (adjusted hazard ratio, 3.58; 95% confidence interval, 1.08-11.87; P = 0.037). Moreover, ZEBRA expression positively correlated with key endocrinological proteins, estrogen receptor α, and aromatase. The transcriptional level of ZEBRA is activated by estrogen in an estrogen receptor α-dependent manner, resulting in an increase in structural gene expression levels and extracellular virus DNA copy number in NPC cell lines, reminiscent of lytic infection. Interestingly, it did not suppress cellular proliferation or increase apoptosis, in contrast to cells treated with 12-O-tetradecanoylphorbol-13-acetate and sodium butyrate, indicating that viral production induced by estrogen is not a cell lytic phenomenon. Our results suggest that intratumoral estrogen overproduced by aromatase could induce ZEBRA expression and EBV reactivation, contributing to the progression of NPC.

NF-κB over-activation portends improved outcomes in HPV-associated head and neck cancer

Evolving understanding of head and neck squamous cell carcinoma (HNSCC) is leading to more specific diagnostic disease classifications. Among HNSCC caused by the human papilloma virus (HPV), tumors harboring defects in TRAF3 or CYLD are associated with improved clinical outcomes and maintenance of episomal HPV. TRAF3 and CYLD are negative regulators of NF-κB and inactivating mutations of either leads to NF-κB overactivity. Here, we developed and validated a gene expression classifier separating HPV+ HNSCCs based on NF-κB activity. As expected, the novel classifier is strongly enriched in NF-κB targets leading us to name it the NF-κB Activity Classifier (NAC). High NF-κB activity correlated with improved survival in two independent cohorts. Using NAC, tumors with high NF-κB activity but lacking defects in TRAF3 or CYLD were identified; thus, while TRAF3 or CYLD gene defects identify the majority of tumors with NF-κB activation, unknown mechanisms leading to NF-kB activity also exist. The NAC correctly classified the functional consequences of two novel CYLD missense mutations. Using a reporter assay, we tested these CYLD mutations revealing that their activity to inhibit NF-kB was equivalent to the wild-type protein. Future applications of the NF-κB Activity Classifier may be to identify HPV+ HNSCC patients with better or worse survival with implications for treatment strategies.

Non-Robustness of Ang’s Risk Classification in Human Papillomavirus-Related Oropharyngeal Squamous Cell Carcinoma in Japanese Patients

Background: Validity of the risk classification by Ang for human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) remains to be studied in the patients treated by modalities other than chemoradiotherapy and in Japanese patients. Materials and Methods: Between 2010 and 2018, 122 patients with HPV-related OPSCC in stages III and IV by the TNM classification 7th edition (TNM-7) were treated curatively at a single institution in Japan. The median age was 62.7 years. Over 50% of the patients underwent surgery with or without adjuvant therapy. The influence of multiple factors on survival was analyzed. Results: The amount of smoking dichotomized at 10 pack-year, which was used in Ang’s risk classification, was not predictive of prognosis, and Ang’s risk classification was not significantly influential on prognosis in multivariate analysis. In the patients treated with definitive radiation therapy, Ang’s risk classification was not predictive of the prognosis in univariate analysis. The impact of smoking was significant only in the patients undergoing the definitive operation. Conclusions: Ang’s risk classification was not robust in predicting the prognosis of general Japanese HPV-related OPSCC patients. The amount of smoking might have different prognostic influences depending on the therapeutic method.

Like Brothers in Arms: How Hormonal Stimuli and Changes in the Metabolism Signaling Cooperate, Leading HPV Infection to Drive the Onset of Cervical Cancer

Despite all precautionary actions and the possibility of using vaccinations to counteract infections caused by human papillomaviruses (HPVs), HPV-related cancers still account for approximately 5% of all carcinomas. Worldwide, many women are still excluded from adequate health care due to their social position and origin. Therefore, immense efforts in research and therapy are still required to counteract the challenges that this disease entails. The special thing about an HPV infection is that it is not only able to trick the immune system in a sophisticated way, but also, through genetic integration into the host genome, to use all the resources available to the host cells to complete the replication cycle of the virus without activating the alarm mechanisms of immune recognition and elimination. The mechanisms utilized by the virus are the metabolic, immune, and hormonal signaling pathways that it manipulates. Since the virus is dependent on replication enzymes of the host cells, it also intervenes in the cell cycle of the differentiating keratinocytes and shifts their terminal differentiation to the uppermost layers of the squamocolumnar transformation zone (TZ) of the cervix. The individual signaling pathways are closely related and equally important not only for the successful replication of the virus but also for the onset of cervical cancer. We will therefore analyze the effects of HPV infection on metabolic signaling, as well as changes in hormonal and immune signaling in the tumor and its microenvironment to understand how each level of signaling interacts to promote tumorigenesis of cervical cancer.

Expression of Sex Hormones in Oral Squamous Cell Carcinoma: A Systematic Review on Immunohistochemical Studies

Oral squamous cell carcinoma (OSCC) is the most widespread oral malignancy. In the western world, smoking and alcohol remain the most common risk factors, whereas smokeless tobacco and areca nut consumption are the prevalent etiological factors in South Asia. Numerous markers were studied till date to identify the disease. However, the role of sex hormones in OSCC is poorly defined. Hormonal receptors play a role in breast cancer, prostate cancer, and human papillomavirus (HPV) driven oropharyngeal cancers. It is proven that the expression of estrogen receptor-α improved the overall survival of the patient with HPV-positive oropharyngeal cancer. Thus, this review article aims to determine the expression of sex hormones by immunohistochemistry in OSCC.

This systematic review was performed with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement Criteria 2020. Relevant articles were collected from the electronic database in PubMed and Cochrane till 2021. Immunohistochemical studies on sex hormones and their role in OSCC published in English literature were included. We excluded case reports, case series, and abstract-only articles. The sample size of the selected studies varied, and these studies measured the parameters such as sex hormones and OSCC. Furthermore, all the studies used different sex hormones and their association with oral cancer through the immunohistochemical process. Thus, this review summarizes that sex hormones influence the biopathology of oral cancer and have a prognostic significance in the tumor subgroups.

High Risk-Human Papillomavirus in HNSCC: Present and Future Challenges for Epigenetic Therapies

Head and Neck Squamous Cell Carcinoma (HNSCC) is a highly heterogeneous group of tumors characterized by an incidence of 650,000 new cases and 350,000 deaths per year worldwide and a male to female ratio of 3:1. The main risk factors are alcohol and tobacco consumption and Human Papillomavirus (HPV) infections. HNSCC cases are divided into two subgroups, the HPV-negative (HPV−) and the HPV-positive (HPV+) which have different clinicopathological and molecular profiles. However, patients are still treated with the same therapeutic regimens. It is thus of utmost importance to characterize the molecular mechanisms underlying these differences to find new biomarkers and novel therapeutic targets towards personalized therapies. Epigenetic alterations are a hallmark of cancer and can be exploited as both promising biomarkers and potential new targets. E6 and E7 HPV oncoviral proteins besides targeting p53 and pRb, impair the expression and the activity of several epigenetic regulators. While alterations in DNA methylation patterns have been well described in HPV+ and HPV− HNSCC, accurate histone post-translational modifications (hPTMs) characterization is still missing. Herein, we aim to provide an updated overview on the impact of HPV on the hPTMs landscape in HNSCC. Moreover, we will also discuss the sex and gender bias in HNSCC and how the epigenetic machinery could be involved in this process, and the importance of taking into account sex and/or gender also in this field.

Molecular prognostic indicators in HPV-positive oropharyngeal cancer: an updated review

Infection with HPV virus and exposure to extrinsic carcinogens are the main causative factors for oropharyngeal squamous cell carcinoma (OPSCC). While HPV-related OPSCC typically shows a better prognosis and may be a candidate for de-intensification therapy, there is a subset of HPV-related cancers that show aggressive phenotype with frequent metastatic spread. The identification and refinement of molecular markers can better serve for prediction of prognosis and thus improve treatment decisions and outcome. We conducted a systematic review according to the PRISMA guidelines of all relevant studies addressing novel biomarkers in publications prior to July 2021. We identified studies that evaluated the association between molecular markers and prognosis in HPV-positive OPSCC. Full-text publications were entirely reviewed, classified, and selected if a clear predictive/prognostic value was seen in patients with HPV-positive OPSCC. Furthermore, a functional analysis of the target genes was conducted to understand biological processes and molecular pathways impacting on HPV-positive OPSCC outcomes. The systematic review yielded a total of 14 studies that matched the inclusion and exclusion criteria. Differential expression was identified for 31 different biomarkers. The first common pattern identified was the association of HPV-related circulating antibodies to activated immune function. Second, gene-gene interaction analysis further identified interacting gene networks tightly implicated in hypoxia tumor metabolism including the Warburg effect. Survival in HPV-positive OPSCC can be predicted by distinct selective biomarkers mainly indicative of immune host response and oxidative metabolism. Among these markers, some were identified to be unsuitable for HPV-positive de-escalation trials aimed at improving patients' quality of life.

Differential Incidence of Tongue Base Cancer in Male and Female HPV16-Transgenic Mice: Role of Female Sex Hormone Receptors

A growing proportion of oropharyngeal squamous cell carcinomas (OPSCC) are associated with infection by high-risk human papillomavirus (HPV). For reasons that remain largely unknown, HPV+OPSCC is significantly more common in men than in women. This study aims to determine the incidence of OPSCC in male and female HPV16-transgenic mice and to explore the role of female sex hormone receptors in the sexual predisposition for HPV+ OPSCC. The tongues of 30-weeks-old HPV16-transgenic male (n = 80) and female (n = 90) and matched wild-type male (n = 10) and female (n = 10) FVB/n mice were screened histologically for intraepithelial and invasive lesions in 2017 at the Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Portugal. Expression of estrogen receptors alpha (ERα) and beta (ERβ), progesterone receptors (PR) and matrix metalloproteinase 2 (MMP2) was studied immunohistochemically. Collagen remodeling was studied using picrosirius red. Female mice showed robust ERα and ERβ expression in intraepithelial and invasive lesions, which was accompanied by strong MMP2 expression and marked collagen remodeling. Male mice showed minimal ERα, ERβ and MMP2 expression and unaltered collagen patterns. These results confirm the association of HPV16 with tongue base cancer in both sexes. The higher cancer incidence in female versus male mice contrasts with data from OPSCC patients and is associated with enhanced ER expression via MMP2 upregulation.

Biologic and behavioral associations of estrogen receptor alpha positivity in head and neck squamous cell carcinoma

OBJECTIVES

Tumor HPV status is an established independent prognostic marker for oropharynx cancer (OPC). Recent studies have reported that tumor estrogen receptor alpha (ERα) positivity is also associated with prognosis independent of HPV. Little is known about the biologic and behavioral predictors of ERα positivity in head and neck squamous cell cancer (HNSCC). We therefore explored this in a multicenter prospective cohort study.

MATERIALS AND METHODS

Participants with HNSCC completed a survey and provided a blood sample. Tumor samples were tested for ERα using immunohistochemistry. ERα positivity was defined as ≥1%, standardized by the American Society of Clinical Oncology/College of American Pathologists in breast cancer. Characteristics were compared with χ² and Fisher's exact test. Odds ratios (OR) were calculated using logistic regression.

RESULTS

Of 318 patients with HNSCC, one third had ERα positive tumors (36.2%, n = 115). Odds of ERα expression were significantly increased in those with HPV-positive tumors (OR = 27.5, 95% confidence interval[CI] 12.1-62), smaller tumors (≤T2, OR = 3.6, 95% CI 1.9-7.1), male sex (OR = 2.0, 95% CI 1.1-3.6), overweight/obesity (BMI ≥ 25, OR = 1.9, 95% CI 1.1-3.3), and those married/living with a partner (OR = 1.7, 95% CI 1.0-3.0). In a multivariate model, HPV-positivity (aOR = 27.5, 95% CI 11.4-66) and small tumor size (≤T2, aOR = 2.2, 95% CI 1.0-4.8) remained independently associated with ERα status. When restricted to OPC (n = 180), tumor HPV status (aOR = 17.1, 95% CI 2.1-137) and small tumor size (≤T2, aOR = 4.0 95% CI 1.4-11.3) remained independently associated with ERα expression.

CONCLUSION

Tumor HPV status and small tumor size are independently associated with ERα expression in HNSCC.

A combination of intra-tumor genetic heterogeneity, estrogen receptor alpha and human papillomavirus status predicts outcomes in head and neck squamous cell carcinoma following chemoradiotherapy

BACKGROUND

Previous work indicates that mutant-allele tumor heterogeneity (MATH), estrogen receptor alpha (ERα) expression, and human papillomavirus (HPV) status provide prognostic utility in head and neck squamous cell carcinoma (HNSCC). We sought to assess whether the combination of these three objective biomarkers could provide better prognostication for patients who receive chemoradiotherapy (CRT).

METHODS

156 patients (75 oral cavity, 44 oropharyngeal and 37 laryngeal squamous cell carcinoma cancer patients) who received CRT as primary therapy or adjuvant to surgery were identified from The Cancer Genome Atlas (TCGA). MATH values were calculated from TCGA whole exome sequencing data, HPV status was determined by mapping RNA-seq reads, and ERα expression was determined from ESR1 mRNA expression data. Relationships among clinical characteristics were assessed by Fisher exact tests. Relationships of clinical characteristics and MATH, ERα and HPV to overall survival were evaluated with Cox proportional hazard analysis.

RESULTS

The combination of poor-prognosis values for all 3 biomarkers (high MATH, low ERα and HPV-negative status) has a predicted hazard ratio of 28.2 (95% CI: 5.4-148, p = 0.0001) versus the combination of their good-prognosis values (low MATH, high ERα and HPV-positive status). Addition of N classification to the combination of these three biomarkers added further prognostic value.

CONCLUSIONS

A combination of these three biomarkers, readily determined on pretreatment biopsy specimens, can stratify patients into prognostic groups. Their application potentially offers numerous opportunities to optimize treatment or explore de-intensification strategies in the clinical trial setting.

Murine leukemia virus resists producer cell APOBEC3A by its Glycosylated Gag but not target cell APOBEC3A

The human APOBEC3A (A3A) polynucleotide cytidine deaminase has been shown to have antiviral activity against HTLV-1 but not HIV-1, when expressed in the virus producer cell. In viral target cells, high levels of endogenous A3A activity have been associated with the restriction of HIV-1 during infection. Here we demonstrate that A3A derived from both target cells and producer cells can block the infection of Moloney-MLV (MLV) and related AKV-derived strains of MLV in a deaminase-dependent mode. Furthermore, glycosylated Gag (glycoGag) of MLV inhibits the encapsidation of human A3A, but target cell A3A was not affected by glycoGag and exerted deamination of viral DNA. Importantly, our results clearly indicate that poor glycoGag expression in MLV gag-pol packaging constructs as compared to abundant levels in full-length amphotropic MLV makes these viral vectors sensitive to A3A-mediated restriction. This raises the possibility of acquiring A3A-induced mutations in retroviral gene therapy applications.

HPV Meets APOBEC: New Players in Head and Neck Cancer

Besides smoking and alcohol, human papillomavirus (HPV) is a factor promoting head and neck squamous cell carcinoma (HNSCC). In some human tumors, including HNSCC, a number of mutations are caused by aberrantly activated DNA-modifying enzymes, such as the apolipoprotein B mRNA editing enzyme catalytic polypeptide-like (APOBEC) family of cytidine deaminases. As the enzymatic activity of APOBEC proteins contributes to the innate immune response to viruses, including HPV, the role of APOBEC proteins in HPV-driven head and neck carcinogenesis has recently gained increasing attention. Ongoing research efforts take the cue from two key observations: (1) APOBEC expression depends on HPV infection status in HNSCC; and (2) APOBEC activity plays a major role in HPV-positive HNSCC mutagenesis. This review focuses on recent advances on the role of APOBEC proteins in HPV-positive vs. HPV-negative HNSCC.

Influences of Semaphorin 3A Expression on Clinicopathological Features, Human Papillomavirus Status, and Prognosis in Oropharyngeal Carcinoma

Human papillomavirus (HPV) infection is now identified as a major etiologic factor for oropharyngeal cancer (OPC), and HPV positivity is well established better prognostic marker in OPC. Now, predictable markers for the prognosis of the patients who are stratified by HPV has been investigated in. Semaphorin 3A (SEMA3A) is a well-known axon guidance molecule in the nervous system. It is also known as a tumor suppressor in various cancers. In the present study, we examined the relationships between SEMA3A and clinicopathologic features, especially HPV status, and neoangiogenesis, and its prognostic significance for OPC patients. Thirty-two OPC patients and 17 normal patients were analyzed for SEMA3A expression by immunohistochemical analysis. We also analyzed 22 OPC specimens for CD34 expression as a marker of neoangiogenesis. SEMA3A was significantly downregulated in OPC compared with chronic tonsillitis tissues (p = 0.005). SEMA3A expression was negatively correlated with CD34 expression (r = −0.466, p = 0.033). Moreover, the higher SEMA3A expression cohort showed better survival than the lower SEMA3A expression cohort regardless of HPV status (p = 0.035). These results suggest that SEMA3A expression is a prognostic marker for survival regardless of HPV status and is associated with anti-angiogenesis in OPC.

Estrogen receptor α as a predictive biomarker for survival in human papillomavirus-positive oropharyngeal squamous cell carcinoma

Background

Although oropharyngeal squamous cell carcinoma (OPSCC) with human papillomavirus (HPV) infection has a good prognosis, the accurate prediction of survival and risk of treatment failure is essential to design deintensification regimens. Here, we investigated estrogen receptor α (ERα) as a prognostic biomarker with therapeutic implications in OPSCC alongside factors associated with HPV infection.

Methods

We performed immunohistochemistry for ERα and p53 using formalin-fixed, paraffin-embedded tissues and assessed the HPV status using p16 immunohistochemistry and HPV DNA testing in 113 consecutive patients with OPSCC treated with surgical resection or radiotherapy/chemoradiotherapy.

Results

ERα expression and p53 alteration was observed in 35.4% and 21.2% OPSCCs; 45.6% and 1.3% p16+/HPV+ OPSCCs; and 11.5% and 76.9% p16− OPSCCs, respectively. These data suggest that OPSCC pathogenesis varies with HPV status. Furthermore, ERα expression was associated with improved overall survival (OS) in both HPV+ (p16+/HPV+ OPSCC) and p16+ (p16+ OPSCC irrespective of HPV status) models (p = 0.005 and p = 0.006, respectively) and with improved OS adjusted for stage (p = 0.037, hazard ratio: 0.109, 95% confidence interval 0.013–0.871) in the p16+ model.

Conclusions

ERα is a potential predictive biomarker for improved survival in both HPV+ and p16+ OPSCC models.

The Relationship between Estrogen-Related Signaling and Human Papillomavirus Positive Cancers

High risk-human papillomaviruses (HPVs) are known carcinogens. Numerous reports have linked the steroid hormone estrogen, and the expression of estrogen receptors (ERs), to HPV-related cancers, although the exact nature of the interactions remains to be fully elucidated. Here we will focus on estrogen signaling and describe both pro and potentially anti-cancer effects of this hormone in HPV-positive cancers. This review will summarize: (1) cell culture-related evidence, (2) animal model evidence, and (3) clinical evidence demonstrating an interaction between estrogen and HPV-positive cancers. This comprehensive review provides insights into the potential relationship between estrogen and HPV. We suggest that estrogen may provide a potential therapeutic for HPV-related cancers, however additional studies are necessary.

Estrogen Attenuates the Growth of Human Papillomavirus-Positive Epithelial Cells

Human papillomaviruses cause around 5% of all human cancers, yet there are no specific antiviral therapeutic approaches available for combatting these cancers. These cancers are currently treated with standard chemoradiation therapy (CRT). Specific antiviral reagents are desperately required, particularly for HPV+HNSCC whose incidence is increasing and for which there are no diagnostic tools available for combatting this disease. Using data from The Cancer Genome Atlas (TCGA), we and others determined that the estrogen receptor alpha (ERα) is overexpressed in HPV+HNSCC and that elevated levels are associated with an improved disease outcome. This has led to the proposal that estrogen treatment could be a novel therapeutic approach for combatting HPV+cancers. Here, we demonstrate that estrogen attenuates the growth of HPV+epithelial cells using multiple mechanisms, supporting the idea that estrogen has potential as a therapeutic agent for the treatment of HPV+HNSCC.

Human papillomaviruses (HPVs) are small, double-stranded DNA viruses that are significant risk factors in the development of cancer, and HPV accounts for approximately 5% of all worldwide cancers. Recent studies using data from The Cancer Genome Atlas (TCGA) have demonstrated that elevated levels of estrogen receptor alpha (ERα) are associated with improved survival in oropharyngeal cancers, and these elevated receptor levels were linked with human papillomavirus-positive cancers (HPV+cancers). There has been a dramatic increase in HPV-related head and neck squamous cell carcinomas (HPV+HNSCCs) over the last 2 decades, and therapeutic options for this ongoing health crisis are a priority; currently, there are no antiviral therapeutics available for combatting HPV+cancers. During our TGCA studies on head and neck cancer, we had also discovered the overexpression of ERα in HPV+cancers. Here, we demonstrate that 17β-estradiol (estrogen) attenuates the growth/cell viability of HPV+cancers in vitro, but not HPV-negative cancer cells. In addition, N/Tert-1 cells (foreskin keratinocytes immortalized with human telomerase reverse transcriptase [hTERT]) containing human papillomavirus 16 (HPV16) have elevated levels of ERα and growth sensitivity after estrogen treatment compared with parental N/Tert-1 cells. Finally, we demonstrate that there are potentially two mechanisms contributing to the attenuation of HPV+ cell growth following estrogen treatment. First, estrogen represses the viral transcriptional long control region (LCR) downregulating early gene expression, including E6/E7. Second, expression of E6 and E7 by themselves sensitizes cells to estrogen. Overall, our results support the recent proposal that estrogen could be exploited therapeutically for the treatment of HPV-positive oral cancers.

IMPORTANCE Human papillomaviruses cause around 5% of all human cancers, yet there are no specific antiviral therapeutic approaches available for combatting these cancers. These cancers are currently treated with standard chemoradiation therapy (CRT). Specific antiviral reagents are desperately required, particularly for HPV+HNSCC whose incidence is increasing and for which there are no diagnostic tools available for combatting this disease. Using data from The Cancer Genome Atlas (TCGA), we and others determined that the estrogen receptor alpha (ERα) is overexpressed in HPV+HNSCC and that elevated levels are associated with an improved disease outcome. This has led to the proposal that estrogen treatment could be a novel therapeutic approach for combatting HPV+cancers. Here, we demonstrate that estrogen attenuates the growth of HPV+epithelial cells using multiple mechanisms, supporting the idea that estrogen has potential as a therapeutic agent for the treatment of HPV+HNSCC.