The HPV16 E6 oncoprotein causes prolonged receptor protein tyrosine kinase signaling and enhances internalization of phosphorylated receptor species

Heregulin and HER3 are prognostic biomarkers in oropharyngeal squamous cell carcinoma

BACKGROUND

Although heregulin and human epidermal growth factor receptor 3 (HER3) are frequently expressed at high levels in patients with head and neck cancer, their prognostic value remains unclear. The authors explored the prognostic significance of heregulin/HER3 expression in patients with oropharyngeal squamous cell carcinoma (OPSCC), taking into account other HER family members as well as p16 status.

METHODS

Ninety-six primary tumor specimens from patients with OPSCC were retrospectively collected and analyzed for heregulin messenger RNA (mRNA) using in situ hybridization and for HER3, epidermal growth factor receptor, and human epidermal growth factor receptor 2 (HER2) using quantitative immunohistochemistry. Heregulin and HER3 mRNA levels were also examined among different tumor types using The Cancer Genome Atlas database.

RESULTS

High heregulin mRNA (> the median) correlated significantly with poor overall survival (OS) (hazard ratio [HR], 8.48; 95% confidence interval [95% CI], 2.17-33.17 [P =.002]) but not disease-free survival (HR, 1.52; 95% CI, 0.64-3.65 [P =.341]) in patients with OPSCC. Heregulin mRNA correlated negatively with OS in both patients with p16-positive (P =.049) and p16-negative (P =.091) OPSCC on univariate analysis. High HER3 (> the median) also correlated with poor OS (HR, 4.68; 95% CI, 1.47-14.90 [P =.009]) on multivariate analysis. Epidermal growth factor receptor levels independently correlated with disease-free survival (P =.025) and inversely correlated with p16 status (P =.012). In addition, The Cancer Genome Atlas data demonstrated that head and neck squamous cell carcinoma exhibits higher heregulin expression compared with other solid tumor types examined.

CONCLUSIONS

High heregulin mRNA and high HER3 protein levels were found to independently correlate with poor OS in patients with OPSCC. These data support targeting HER3 in patients with heregulin-high OPSCC and warrant further clinical investigation.

High-risk human papillomavirus targets crossroads in immune signaling

Persistent infections with a high-risk type human papillomavirus (hrHPV) can progress to cancer. High-risk HPVs infect keratinocytes (KCs) and successfully suppress host immunity for up to two years despite the fact that KCs are well equipped to detect and initiate immune responses to invading pathogens. Viral persistence is achieved by active interference with KCs innate and adaptive immune mechanisms. To this end hrHPV utilizes proteins encoded by its viral genome, as well as exploits cellular proteins to interfere with signaling of innate and adaptive immune pathways. This results in impairment of interferon and pro-inflammatory cytokine production and subsequent immune cell attraction, as well as resistance to incoming signals from the immune system. Furthermore, hrHPV avoids the killing of infected cells by interfering with antigen presentation to antigen-specific cytotoxic T lymphocytes. Thus, hrHPV has evolved multiple mechanisms to avoid detection and clearance by both the innate and adaptive immune system, the molecular mechanisms of which will be dealt with in detail in this review.

The role of the PI3K/Akt/mTOR signalling pathway in human cancers induced by infection with human papillomaviruses

Infection with Human papillomaviruses (HPVs) leads to the development of a wide-range of cancers, accounting for 5% of all human cancers. A prominent example is cervical cancer, one of the leading causes of cancer death in women worldwide. It has been well established that tumor development and progression induced by HPV infection is driven by the sustained expression of two oncogenes E6 and E7. The expression of E6 and E7 not only inhibits the tumor suppressors p53 and Rb, but also alters additional signalling pathways that may be equally important for transformation. Among these pathways, the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signalling cascade plays a very important role in HPV-induced carcinogenesis by acting through multiple cellular and molecular events. In this review, we summarize the frequent amplification of PI3K/Akt/mTOR signals in HPV-induced cancers and discuss how HPV oncogenes E6/E7/E5 activate the PI3K/Akt/mTOR signalling pathway to modulate tumor initiation and progression and affect patient outcome. Improvement of our understanding of the mechanism by which the PI3K/Akt/mTOR signalling pathway contributes to the immortalization and carcinogenesis of HPV-transduced cells will assist in devising novel strategies for preventing and treating HPV-induced cancers.

Cytotoxic effect of lapatinib is restricted to human papillomavirus-positive head and neck squamous cell carcinoma cell lines

Background

Lapatinib is a dual epidermal growth factor receptor (EGFR) and HER2 inhibitor. Overexpression of these receptors is frequently observed in head and neck squamous cell carcinoma (HNSCC). As growing proportion of HNSCC is characterized by human papillomavirus (HPV) infection, we aimed at evaluating the efficacy of lapatinib as function of HPV status in HNSCC cell lines.

Methods

Two HPV-positive and two HPV-negative HNSCC cell lines were used. Proliferation, cell cycle, and Annexin V assays were performed to test their sensitivity to lapatinib. Combination of lapatinib and ionizing radiation was evaluated with clonogenic survival assays. Akt, EGFR and HER2, and E6/E7 expression and activation were analyzed by immunoblotting and quantitative reverse transcription polymerase chain reaction.

Results

Lapatinib reduced E6 and E7 expression and Akt phosphorylation, inhibited cell proliferation and induced cell death in HPV-positive cell lines. An additive effect of lapatinib with radiation was observed in these cells. Lapatinib had no effect on HPV-negative cells.

Conclusion

Lapatinib efficacy restricted to the HPV-positive cells suggests that HPV status could be a potential marker for enhanced response to lapatinib in HNSCC.

TALEN-mediated targeting of HPV oncogenes ameliorates HPV-related cervical malignancy

Persistent HPV infection is recognized as the main etiologic factor for cervical cancer. HPV expresses the oncoproteins E6 and E7, both of which play key roles in maintaining viral infection and promoting carcinogenesis. While siRNA-mediated targeting of E6 and E7 transcripts temporarily induces apoptosis in HPV-positive cells, it does not eliminate viral DNA within the host genome, which can harbor escape mutants. Here, we demonstrated that specifically targeting E6 and E7 within host DNA with transcription activator-like effector nucleases (TALENs) induces apoptosis, inhibits growth, and reduces tumorigenicity in HPV-positive cell lines. TALEN treatment efficiently disrupted E6 and E7 oncogenes, leading to the restoration of host tumor suppressors p53 and retinoblastoma 1 (RB1), which are targeted by E6 and E7, respectively. In the K14-HPV16 transgenic mouse model of HPV-driven neoplasms, direct cervical application of HPV16-E7-targeted TALENs effectively mutated the E7 oncogene, reduced viral DNA load, and restored RB1 function and downstream targets transcription factor E2F1 and cycling-dependent kinase 2 (CDK2), thereby reversing the malignant phenotype. Together, the results from our study suggest that TALENs have potential as a therapeutic strategy for HPV infection and related cervical malignancy.

NF-κB-induced KIAA1199 promotes survival through EGFR signalling

Constitutive activation of EGFR- and NF-κB-dependent pathways is a hallmark of cancer, yet signalling proteins that connect both oncogenic cascades are poorly characterized. Here we define KIAA1199 as a BCL-3- and p65-dependent gene in transformed keratinocytes. KIAA1199 expression is enhanced on human papillomavirus (HPV) infection and is aberrantly expressed in clinical cases of cervical (pre)neoplastic lesions. Mechanistically, KIAA1199 binds Plexin A2 and protects from Semaphorin 3A-mediated cell death by promoting EGFR stability and signalling. Moreover, KIAA1199 is an EGFR-binding protein and KIAA1199 deficiency impairs EGF-dependent Src, MEK1 and ERK1/2 phosphorylations. Therefore, EGFR stability and signalling to downstream kinases requires KIAA1199. As such, KIAA1199 promotes EGF-mediated epithelial-mesenchymal transition (EMT). Taken together, our data define KIAA1199 as an oncogenic protein induced by HPV infection and constitutive NF-κB activity that transmits pro-survival and invasive signals through EGFR signalling.

Human viral oncogenesis: a cancer hallmarks analysis

Approximately 12% of all human cancers are caused by oncoviruses. Human viral oncogenesis is complex, and only a small percentage of the infected individuals develop cancer, often many years to decades after the initial infection. This reflects the multistep nature of viral oncogenesis, host genetic variability, and the fact that viruses contribute to only a portion of the oncogenic events. In this review, the Hallmarks of Cancer framework of Hanahan and Weinberg (2000 and 2011) is used to dissect the viral, host, and environmental cofactors that contribute to the biology of multistep oncogenesis mediated by established human oncoviruses. The viruses discussed include Epstein-Barr virus (EBV), high-risk human papillomaviruses (HPVs), hepatitis B and C viruses (HBV and HCV, respectively), human T cell lymphotropic virus-1 (HTLV-1), and Kaposi's sarcoma herpesvirus (KSHV).

De-escalation treatment protocols for human papillomavirus-associated oropharyngeal squamous cell carcinoma: a systematic review and meta-analysis of current clinical trials

Iatrogenic complications associated with current treatment protocols for oropharyngeal squamous cell carcinoma are noted to cause high rates of acute and chronic morbidity. The aims of this study are to provide an overview of the current de-escalation trials for human papillomavirus positive (HPV+) oropharyngeal carcinoma and to evaluate the evidence supporting improved response to treatment of patients within this viral cohort. This study reviewed all completed or in progress randomised controlled trials (RCTs) assessing clinical interventions for human papillomavirus-associated locally advanced oropharyngeal squamous cell carcinoma. We utilised a validated 'risk of bias' tool to assess study quality. We identified nine RCTs that met the full inclusion criteria for this review (all of which are currently on-going and will report from 2015 onwards). Five RCTs performed a post hoc analysis by HPV status, which allowed meta-analysis of 1130 patients. The data reveal a significant difference in overall survival (hazard ratio (HR) 0.49 [95% confidence interval (CI) 0.35-0.69]), loco-regional failure (HR 0.43 [95% CI 0.17-1.11]) and disease specific survival (0.41 [95% 0.3-0.56]) in favour of the HPV+ category. In considering de-escalation treatment protocols, nine studies are currently ongoing. Our meta-analysis provides strong evidence for an improved prognosis in the viral associated cohort when treated by platinum based chemotherapy in combination with radiotherapy or primary radiotherapy. So far, one trial (with moderate to high risk of bias) suggests a reduced survival outcome for the HPV+ population when using the epidermal growth factor receptor (EGFR) inhibitor cetuximab.

The human adenovirus E4-ORF1 protein subverts discs large 1 to mediate membrane recruitment and dysregulation of phosphatidylinositol 3-kinase

Adenoviruses infect epithelial cells lining mucous membranes to cause acute diseases in people. They are also utilized as vectors for vaccination and for gene and cancer therapy, as well as tools to discover mechanisms of cancer due to their tumorigenic potential in experimental animals. The adenovirus E4-ORF1 gene encodes an oncoprotein that promotes viral replication, cell survival, and transformation by activating phosphatidylinositol 3-kinase (PI3K). While the mechanism of activation is not understood, this function depends on a complex formed between E4-ORF1 and the membrane-associated cellular PDZ protein Discs Large 1 (Dlg1), a common viral target having both tumor suppressor and oncogenic functions. Here, we report that in human epithelial cells, E4-ORF1 interacts with the regulatory and catalytic subunits of PI3K and elevates their levels. Like PI3K activation, PI3K protein elevation by E4-ORF1 requires Dlg1. We further show that Dlg1, E4-ORF1, and PI3K form a ternary complex at the plasma membrane. At this site, Dlg1 also co-localizes with the activated PI3K effector protein Akt, indicating that the ternary complex mediates PI3K signaling. Signifying the functional importance of the ternary complex, the capacity of E4-ORF1 to induce soft agar growth and focus formation in cells is ablated either by a mutation that prevents E4-ORF1 binding to Dlg1 or by a PI3K inhibitor drug. These results demonstrate that E4-ORF1 interacts with Dlg1 and PI3K to assemble a ternary complex where E4-ORF1 hijacks the Dlg1 oncogenic function to relocate cytoplasmic PI3K to the membrane for constitutive activation. This novel mechanism of Dlg1 subversion by adenovirus to dysregulate PI3K could be used by other pathogenic viruses, such as human papillomavirus, human T-cell leukemia virus type 1, and influenza A virus, which also target Dlg1 and activate PI3K in cells.

Adenoviruses cause acute illnesses in people, and are additionally utilized both as vehicles to cure genetic diseases, fight cancer, and deliver vaccines, and as tools to discover how cancers develop due to a capacity to generate tumors in experimental animals. The adenovirus E4-ORF1 protein reprograms cell metabolism to enhance virus production in infected cells and promotes cell survival and tumors by activating the important cellular protein phosphatidylinositol 3-kinase (PI3K). How E4-ORF1 activates PI3K is not known, though this function depends on E4-ORF1 binding to the membrane-associated cellular protein Discs Large 1 (Dlg1), which many different viruses evolved to target. In this study, we identify PI3K as a new direct target of E4-ORF1. Results further show that E4-ORF1 binds to PI3K in the cytoplasm and delivers it to Dlg1 at the membrane where the three proteins form a complex that activates PI3K and induces oncogenic growth in cells. This novel molecular mechanism in which adenovirus subverts Dlg1 to dysregulate PI3K may serve as a paradigm to understand PI3K activation mediated by other important pathogenic viruses, such as human papillomavirus, human T-cell leukemia virus type 1, and influenza A virus, which also target Dlg1 in infected cells.

Erlotinib, erlotinib-sulindac versus placebo: a randomized, double-blind, placebo-controlled window trial in operable head and neck cancer

PURPOSE

The EGF receptor (EGFR) and COX2 pathways are upregulated in head and neck squamous cell carcinoma (HNSCC). Preclinical models indicate synergistic antitumor activity from dual blockade. We conducted a randomized, double-blind, placebo-controlled window trial of erlotinib, an EGFR inhibitor; erlotinib plus sulindac, a nonselective COX inhibitor; versus placebo.

EXPERIMENTAL DESIGN

Patients with untreated, operable stage II-IVb HNSCC were randomized 5:5:3 to erlotinib, erlotinib-sulindac, or placebo. Tumor specimens were collected before and after seven to 14 days of treatment. The primary endpoint was change in Ki67 proliferation index. We hypothesized an ordering effect in Ki67 reduction: erlotinib-sulindac > erlotinib > placebo. We evaluated tissue microarrays by immunohistochemistry for pharmacodynamic modulation of EGFR and COX2 signaling intermediates.

RESULTS

From 2005-2009, 47 patients were randomized for the target 39 evaluable patients. Thirty-four tumor pairs were of sufficient quality to assess biomarker modulation. Ki67 was significantly decreased by erlotinib or erlotinib-sulindac (omnibus comparison, two-sided Kruskal-Wallis, P = 0.04). Wilcoxon pairwise contrasts confirmed greater Ki67 effect in both erlotinib groups (erlotinib-sulindac vs. placebo, P = 0.043; erlotinib vs. placebo, P = 0.027). There was a significant trend in ordering of Ki67 reduction: erlotinib-sulindac > erlotinib > placebo (two-sided exact Jonckheere-Terpstra, P = 0.0185). Low baseline pSrc correlated with greater Ki67 reduction (R(2) = 0.312, P = 0.024).

CONCLUSIONS

Brief treatment with erlotinib significantly decreased proliferation in HNSCC, with additive effect from sulindac. Efficacy studies of dual EGFR-COX inhibition are justified. pSrc is a potential resistance biomarker for anti-EGFR therapy, and warrants investigation as a molecular target.

Photon-induced cell migration and integrin expression promoted by DNA integration of HPV16 genome

BACKGROUND

Persistent human papilloma virus 16 (HPV16) infections are a major cause of cervical cancer. The integration of the viral DNA into the host genome causes E2 gene disruption which prevents apoptosis and increases host cell motility. In cervical cancer patients, survival is limited by local infiltration and systemic dissemination. Surgical control rates are poor in cases of parametrial infiltration. In these patients, radiotherapy (RT) is administered to enhance local control. However, photon irradiation itself has been reported to increase cell motility. In cases of E2-disrupted cervical cancers, this phenomon would impose an additional risk of enhanced tumor cell motility. Here, we analyze mechanisms underlying photon-increased migration in keratinocytes with differential E2 gene status.

METHODS

Isogenic W12 (intact E2 gene status) and S12 (disrupted E2 gene status) keratinocytes were analyzed in fibronectin-based and serum-stimulated migration experiments following single photon doses of 0, 2, and 10 Gy. Quantitative FACS analyses of integrin expression were performed.

RESULTS

Migration and adhesion are increased in E2 gene-disrupted keratinocytes. E2 gene disruption promotes attractability by serum components, therefore, effectuating the risk of local infiltration and systemic dissemination. In S12 cells, migration is further increased by photon RT which leads to enhanced expression of fibronectin receptor integrins.

CONCLUSION

HPV16-associated E2 gene disruption is a main predictor of treatment-refractory cancer virulence. E2 gene disruption promotes cell motility. Following photon RT, E2-disrupted tumors bear the risk of integrin-related infiltration and dissemination.

Impact of human papilloma virus infection on the response of head and neck cancers to anti-epidermal growth factor receptor antibody therapy

Infection with human papillomaviruses (HPVs) characterizes a distinct subset of head and neck squamous cell cancers (HNSCCs). HPV-positive HNSCC preferentially affect the oropharynx and tonsils. Localized HPV-positive HNSCCs have a favorable prognosis and treatment outcome. However, the impact of HPV in advanced or metastatic HNSCC remains to be defined. In particular, it is unclear whether HPV modulates the response to cetuximab, an antibody targeting the epidermal growth factor receptor (EGFR), which is a mainstay of treatment of advanced HNSCC. To this end, we have examined the sensitivity of HPV-positive and -negative HNSCC models to cetuximab and cytotoxic drugs in vitro and in vivo. In addition, we have stably expressed the HPV oncogenes E6 and E7 in cetuximab-sensitive cancer cell lines to specifically investigate their role in the antibody response. The endogenous HPV status or the expression of HPV oncogenes had no significant impact on cetuximab-mediated suppression of EGFR signaling and proliferation in vitro. Cetuximab effectively inhibited the growth of E6- and E7-expressing tumors grafted in NOD/SCID mice. In support, formalin-fixed, paraffin-embedded tumor samples from cetuximab-treated patients with recurrent or metastatic HNSCC were probed for p16^INK4a expression, an established biomarker of HPV infection. Response rates (45.5% versus 45.5%) and median progression-free survival (97 versus 92 days) following cetuximab-based therapy were similar in patients with p16^INK4A-positive and p16^INK4A-negative tumors. In conclusion, HPV oncogenes do not modulate the anti-EGFR antibody response in HSNCC. Cetuximab treatment should be administered independently of HPV status.

Promising systemic immunotherapies in head and neck squamous cell carcinoma

Patients with head and neck squamous cell carcinoma (HNSCC) demonstrate poor survival and significant treatment morbidity with standard therapy. The immune profile in HNSCC, whether caused by carcinogen exposure or human papillomavirus (HPV), is notably immunosuppressive. Early clinical trials of immunotherapy in HNSCC were troubled by systemic toxicity or difficulties in local administration. Now, interest in immunotherapy has been revitalized by mechanistic insights into immune evasion by HNSCC, coupled to ongoing development of novel immunotherapies. This review will summarize immune escape mechanisms in HNSCC, namely downregulation of tumor antigen (TA) presentation, aberrant regulation of the signal transducer and activator of transcription (STAT) family, the immunosuppressive cytokine milieu, and dysregulation of immune effector cells. Therapeutic strategies hypothesized to specifically counter HNSCC immunosuppression will then be discussed. We will survey TA- targeted monoclonal antibodies (mAb), including the prototype cetuximab, as well as adjunctive strategies to enhance antibody-dependent cell-mediated cytotoxicity. We will review immunomodulation to restore STAT1/STAT3 activation balance. Examples of mAb therapy to block immunosuppressive cytokines, such as interleukin-6 or VEGF, will be provided. mAbs which release co-inhibitory T cell receptors such as CTLA-4 and PD-1, overexpressed in HNSCC, also hold therapeutic promise. Finally, we will describe principles for therapeutic vaccination in HPV-associated HNSCC, where non-host TAs such as viral oncoproteins represent ideal targets, and HPV-negative HNSCC, where p53 is a promising target. Insights into immunosuppression in HNSCC have elucidated mechanistic targets for immunotherapy. Rational clinical investigation may lead to effective stand alone or combinatorial treatment approaches.

A conserved C-terminal sequence of high-risk cutaneous beta-human papillomavirus E6 proteins alters localization and signalling of β1-integrin to promote cell migration

Beta-human papillomaviruses (β-HPV) infect cutaneous epithelia, and accumulating evidence suggests that the virus may act as a co-factor with UV-induced DNA damage in the development and progression of non-melanoma skin cancer, although the molecular mechanisms involved are poorly understood. The E6 protein of cutaneous β-HPV types encodes functions consistent with a role in tumorigenesis, and E6 expression can result in papilloma formation in transgenic animals. The E6 proteins of high-risk α-HPV types, which are associated with the development of anogenital cancers, have a conserved 4 aa motif at their extreme C terminus that binds to specific PDZ domain-containing proteins to promote cell invasion. Likewise, the high-risk β-HPVs HPV5 and HPV8 E6 proteins also share a conserved C-terminal motif, but this is markedly different from that of α-HPV types, implying functional differences. Using binding and functional studies, we have shown that β-HPV E6 proteins target β1-integrin using this C-terminal motif. E6 expression reduced membrane localization of β1-integrin, but increased overall levels of β1-integrin protein and its downstream effector focal adhesion kinase in human keratinocytes. Altered β1-integrin localization due to E6 expression was associated with actin cytoskeleton rearrangement and increased cell migration that was abolished by point mutations in the C-terminal motif of E6. We concluded that modulation of β1-integrin signalling by E6 proteins may contribute towards the pathogenicity of these β-HPV types.

Nip the HPV encoded evil in the cancer bud: HPV reshapes TRAILs and signaling landscapes

HPV encoded proteins can elicit ectopic protein–protein interactions that re-wire signaling pathways, in a mode that promotes malignancy. Moreover, accumulating data related to HPV is now providing compelling substantiation of a central role played by HPV in escaping immunosurveillance and impairment of apoptotic response. What emerges is an intricate network of Wnt, TGF, Notch signaling cascades that forms higher-order ligand–receptor complexes routing downstream signaling in HPV infected cells. These HPV infected cells are regulated both extracellularly by ligand receptor axis and intracellularly by HPV encoded proteins and impair TRAIL mediated apoptosis. We divide this review into different sections addressing how linear signaling pathways integrate to facilitate carcinogenesis and compounds that directly or indirectly reverse these aberrant interactions offer new possibilities for therapy in cancer. Although HPV encoded proteins mediated misrepresentation of pathways is difficult to target, improved drug-discovery platforms and new technologies have facilitated the discovery of agents that can target dysregulated pathways in HPV infected cervical cancer cells, thus setting the stage for preclinical models and clinical trials.

Epidermal growth factor receptor inhibitor therapy for recurrent respiratory papillomatosis

The epidermal growth factor pathway has been implicated in various tumors, including human papillomavirus (HPV) lesions such as recurrent respiratory papillomatosis (RRP). Due to the presence of epidermal growth factor receptors in RRP, epidermal growth factor receptor (EGFR) inhibitors have been utilized as adjuvant therapy. This case series examines the response to EGFR inhibitors in RRP. Four patients with life-threatening RRP were treated with EGFR inhibitors. Operative frequency and anatomical Derkay scores were calculated prior to, and following EGFR inhibitor treatment via retrospective chart review. The anatomical Derkay score decreased for all four patients after initiation of EGFR inhibitor therapy. In one patient, the operative frequency increased after switching to an intravenous inhibitor after loss of control with an oral inhibitor. In the other patients there was a greater than 20% decrease in operative frequency in one and a more than doubling in the time between procedures in two.  This study suggests that EGFR inhibitors are a potential adjuvant therapy in RRP and deserve further study in a larger number of patients.