HPV16 E5 expression induces switching from FGFR2b to FGFR2c and epithelial‐mesenchymal transition

Epidermal growth factor receptor-dependent stimulation of differentiation by human papillomavirus type 16 E5

Human papillomaviruses (HPVs) infect keratinocytes of stratified squamous epithelia, and persistent infection with high-risk HPV types, such as HPV16, may lead to the development of malignancies. HPV evades host immunity in part by linking its gene expression to the host differentiation program, and therefore relies on differentiation to complete its life cycle. Based on previous reports indicating that the HPV16 protein E5 is important in the late stages of the differentiation-dependent life cycle, we found that organotypic cultures harboring HPV16 genomes lacking E5 showed reduced markers of terminal differentiation compared to wild type HPV16-containing cultures. We found that epidermal growth factor receptor (EGFR) levels and activation were increased in an E5-depdendent manner in these tissues, and that EGFR promoted terminal differentiation and expression of the HPV16 L1 gene. These findings suggest a function for E5 in preserving the ability of HPV16 containing keratinocytes to differentiate, thus facilitating the production of new virus progeny.

Advances in molecular mechanism of HPV16 E5 oncoprotein carcinogenesis

For a considerable duration, cervical cancer has posed a significant risk to the well-being and survival of women. The emergence and progression of cervical cancer have garnered extensive attention, with prolonged chronic infection of HPV serving as a crucial etiological factor. Consequently, investigating the molecular mechanism underlying HPV-induced cervical cancer has become a prominent research area. The HPV molecule is composed of a long control region (LCR), an early coding region and a late coding region.The early coding region encompasses E1, E2, E4, E5, E6, E7, while the late coding region comprises L1 and L2 ORF.The investigation into the molecular structure and function of HPV has garnered significant attention, with the aim of elucidating the carcinogenic mechanism of HPV and identifying potential targets for the treatment of cervical cancer. Research has demonstrated that the HPV gene and its encoded protein play a crucial role in the invasion and malignant transformation of host cells. Consequently, understanding the function of HPV oncoprotein is of paramount importance in comprehending the pathogenesis of cervical cancer. E6 and E7, the primary HPV oncogenic proteins, have been the subject of extensive study. Moreover, a number of contemporary investigations have demonstrated the significant involvement of HPV16 E5 oncoprotein in the malignant conversion of healthy cells through its regulation of cell proliferation, differentiation, and apoptosis via diverse pathways, albeit the precise molecular mechanism remains unclear. This manuscript aims to provide a comprehensive account of the molecular structure and life cycle of HPV.The HPV E5 oncoprotein mechanism modulates cellular processes such as proliferation, differentiation, apoptosis, and energy metabolism through its interaction with cell growth factor receptors and other cellular proteins. This mechanism is crucial for the survival, adhesion, migration, and invasion of tumor cells in the early stages of carcinogenesis. Recent studies have identified the HPV E5 oncoprotein as a promising therapeutic target for early-stage cervical cancer, thus offering a novel approach for treatment.

FGFR2c Upregulation Contributes to Cancer-Associated Fibroblast Program Activation and to Enhanced Autophagy in Actinic Keratosis-Derived Dermal Fibroblasts: A Possible Role in Precancerous Cell/Stromal Cell Crosstalk

Actinic keratosis (AK) is a preneoplastic skin disorder which can rapidly progress to cutaneous squamous cell carcinomas (SCCs). In light of our previous findings, indicating a possible oncogenic role of the mesenchymal isoform of FGFR2 (FGFR2c) aberrantly expressed in AK keratinocytes, we analyzed the possible tumor-promoting role of this receptor in the stromal AK counterpart in this work. Molecular analysis showed that, particularly in early AK lesions, FGFR2c dermal upregulation is accompanied by the downregulation of the cancer-associated fibroblasts (CAF) transcription repressor CSL, the upregulation of the CAF activator ULK3, and the consequent CAF gene induction. Immunofluorescence and molecular analysis, coupled with silencing approaches by siRNA, applied on primary cultures of KIN I-derived fibroblasts, indicated that FGFR2c upregulation contribute to CAF signature and the increased autophagy in response to FGF2. Magnetic bead-based multiplex assay, combined with FGFR2 signaling shut-off approaches, indicated that, especially in response to FGF2, IL-6 secretion could depend on FGFR2c high expression and signaling, suggesting the possible establishment of FGFR2c-dependent secretory autophagy, contributing to tumor-promoting factor release. Overall, our results identified FGFR2c as a signaling molecule involved in controlling precancerous/stromal cell oncogenic crosstalk, pointing to this receptor as a possible early molecular marker predictive for AK’s rapid malignant progression.

An integrative approach toward identification and analysis of therapeutic targets involved in HPV pathogenesis with a focus on carcinomas

BACKGROUND

Persistent infection of high-risk HPVs is known to cause diverse carcinomas, mainly cervical, oropharyngeal, penile, etc. However, efficient treatment is still lacking.

OBJECTIVE

Identify and analyze potential therapeutic targets involved in HPV oncogenesis and repurposing drug candidates.

METHODS

Integrative analyses were performed on the compendium of 1887 HPV infection-associated or integration-driven disrupted genes cataloged from the Open Targets Platform and HPVbase resource. Potential target genes are prioritized using STRING, Cytoscape, cytoHubba, and MCODE. Gene ontology and KEGG pathway enrichment analysis are performed. Further, TCGA cancer genomic data of CESC and HNSCC is analyzed. Moreover, regulatory networks are also deduced by employing NetworkAnalyst.

RESULTS

We have implemented a unique approach for identifying and prioritizing druggable targets and repurposing drug candidates against HPV oncogenesis. Overall, hundred key genes with 44 core targets were prioritized with transcription factors (TFs) and microRNAs (miRNAs) regulators pertinent to HPV pathogenesis. Genomic alteration profiling further substantiated our findings. Among identified druggable targets, TP53, NOTCH1, PIK3CA, EP300, CREBBP, EGFR, ERBB2, PTEN, and FN1 are frequently mutated in CESC and HNSCC. Furthermore, PIK3CA, CCND1, RFC4, KAT5, MYC, PTK2, EGFR, and ERBB2 show significant copy number gain, and FN1, CHEK1, CUL1, EZH2, NRAS, and H2AFX was marked for the substantial copy number loss in both carcinomas. Likewise, under-explored relevant regulators, i.e., TFs (HINFP, ARID3A, NFATC2, NKX3-2, EN1) and miRNAs (has-mir-98-5p, has-mir-24-3p, has-mir-192-5p, has-mir-519d-3p) is also identified.

CONCLUSIONS

We have identified potential therapeutic targets, transcriptional and post-transcriptional regulators to explicate HPV pathogenesis as well as potential repurposing drug candidates. This study would aid in biomarker and drug discovery against HPV-mediated carcinoma.

Underlying mechanisms of epithelial splicing regulatory proteins in cancer progression

Cancer is the second-leading disease-related cause of global mortality after cardiovascular disease. Despite significant advances in cancer therapeutic strategies, cancer remains one of the major obstacles to human life extension. Cancer pathogenesis is extremely complicated and not fully understood. Epithelial splicing regulatory proteins (ESRPs), including ESRP1 and ESRP2, belong to the heterogeneous nuclear ribonucleoprotein family of RNA-binding proteins and are crucial regulators of the alternative splicing of messenger RNAs (mRNAs). The expression and activity of ESRPs are modulated by various mechanisms, including post-translational modifications and non-coding RNAs. Although a growing body of evidence suggests that ESRP dysregulation is closely associated with cancer progression, the detailed mechanisms remain inconclusive. In this review, we summarize recent findings on the structures, functions, and regulatory mechanisms of ESRPs and focus on their underlying mechanisms in cancer progression. We also highlight the clinical implications of ESRPs as prognostic biomarkers and therapeutic targets in cancer treatment. The information reviewed herein could be extremely beneficial to the development of individualized therapeutic strategies for cancer patients.

The Interaction of Human Papillomavirus Infection and Prostaglandin E2 Signaling in Carcinogenesis: A Focus on Cervical Cancer Therapeutics

Chronic infection by high-risk human papillomaviruses (HPV) and chronic inflammation are factors associated with the onset and progression of several neoplasias, including cervical cancer. Oncogenic proteins E5, E6, and E7 from HPV are the main drivers of cervical carcinogenesis. In the present article, we review the general mechanisms of HPV-driven cervical carcinogenesis, as well as the involvement of cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) and downstream effectors in this pathology. We also review the evidence on the crosstalk between chronic HPV infection and PGE2 signaling, leading to immune response weakening and cervical cancer development. Finally, the last section updates the current therapeutic and preventive options targeting PGE2-derived inflammation and HPV infection in cervical cancer. These treatments include nonsteroidal anti-inflammatory drugs, prophylactic and therapeutical vaccines, immunomodulators, antivirals, and nanotechnology. Inflammatory signaling pathways are closely related to the carcinogenic nature of the virus, highlighting inflammation as a co-factor for HPV-dependent carcinogenesis. Therefore, blocking inflammatory signaling pathways, modulating immune response against HPV, and targeting the virus represent excellent options for anti-tumoral therapies in cervical cancer.

The FGFR2c/PKCε Axis Controls MCL-1-Mediated Invasion in Pancreatic Ductal Adenocarcinoma Cells: Perspectives for Innovative Target Therapies

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy whose main characterizations are Kirsten Rat Sarcoma-activating mutations (KRAS) and a highly aggressive phenotype. Based on our recent findings demonstrating that the highly aberrant expression of the mesenchymal isoform of Fibroblast Growth Factor Receptor 2 (FGFR2c) in PDAC cells activates Protein-Kinase C Epsilon (PKCε), which in turn controls receptor-mediated epithelial to mesenchymal transition (EMT), here we investigated the involvement of these signaling events in the establishment of additional tumorigenic features. Using PDAC cell lines expressing divergent levels of the FGFR2c and stable protein depletion approaches by short hairpin RNA (shRNA), we found that FGFR2c expression and its PKCε downstream signaling are responsible for the invasive response to Fibroblast Growth Factor 2 (FGF2) and for anchorage-independent growth. In addition, in vitro clonogenic assays, coupled with the check of the amount of cleaved Poly Adenosine Diphosphate-Ribose Polymerase 1 (PARP1) by Western blot, highlighted the involvement of both FGFR2c and PKCε in cell viability. Finally, monitoring of Myeloid Cell Leukemia 1 (MCL-1) expression and Sarcoma kinase family (SRC) phosphorylation suggested that the FGFR2c/PKCε axis could control cell migration/invasion possibly via MCL-1/SRC-mediated reorganization of the actin cytoskeleton. Being PKCs RAS-independent substrates, the identification of PKCε as a hub molecule downstream FGFR2c at the crossroad of signaling networks governing the main malignant tumor hallmarks could represent an important advance towards innovative target therapies overcoming RAS.

FGF signalling facilitates cervical cancer progression

Cervical cancer is one of the most frequently diagnosed cancers in women worldwide. While cervical cancer is caused by human papillomavirus (HPV), not all females infected with HPV develop the disease, suggesting that other factors might facilitate its progression. Growing evidence supports the involvement of the fibroblast growth factor receptor (FGFR) axis in several cancers, including gynecological. However, for cervical cancer, the molecular mechanisms that underpin the disease remain poorly understood, including the role of FGFR signaling. The aim of this study was to investigate FGF(R) signaling in cervical cancer through bioinformatic analysis of cell line and patient data and through detailed expression profiling, manipulation of the FGFR axis, and downstream phenotypic analysis in cell lines (HeLa, SiHa, and CaSki). Expression (protein and mRNA) analysis demonstrated that FGFR1b/c, FGFR2b/c, FGFR4, FGF2, FGF4, and FGF7 were expressed in all three lines. Interestingly, FGFR1 and 2 localized to the nucleus, supporting that nuclear FGFRs could act as transcription factors. Importantly, 2D and 3D cell cultures demonstrated that FGFR activation can facilitate cell functions correlated with invasive disease. Collectively, this study supports an association between FGFR signaling and cervical cancer progression, laying the foundations for the development of therapeutic approaches targeting FGFR in this disease.

HPV-induced cancers: preclinical therapeutic advancements

INTRODUCTION

High-risk HPV infections are related to several epithelial cancers. Despite the availability of prophylactic vaccines, HPV infections are still responsible for about 5% of all human malignancies worldwide. While therapeutic vaccines are ongoing clinical trials, genotoxic agents and surgical interventions represent current clinical treatments, with no specific anti-HPV drugs yet available in the clinics.

AREAS COVERED

We offer a comprehensive report of small molecules in preclinical studies proposed as potential anticancer agents against HPV-driven tumors. Given the importance of HPV oncoproteins for cancer maintenance, particularly E6 and E7, we present a classification of both non-targeted and targeted agents, with a further subdivision of the latter into two categories according to their either direct or indirect activity against viral protein functions.

EXPERT OPINION

Prophylactic vaccines can prevent the insurgence of HPV-related cancers, but have no effect against pre-existing infections. Moreover, their high cost, genotype-restricted effect and the growing worldwide distrust for vaccines make the availability of a specific drug an unmet medical need. Different viral early proteins emerge as ideal candidates for drug development. We highlight the most promising strategies and address future challenges in this field to herald the prospect of a specific therapeutic regimen against HPV-related cancers.

The Not-So-Good, the Bad and the Ugly: HPV E5, E6 and E7 Oncoproteins in the Orchestration of Carcinogenesis

Infection with HPV starts with the access of the viral particles to basal cells in the epidermis, potentially via microtraumas to the skin. The basal cells are able to keep away these pathogens in normal circumstances through a robust immune response from the host, as HPV infections are, in general, cleared within 2 to 3 weeks. However, the rare instances of persistent infection and/or in cases where the host immune system is compromised are major risk factors for the development of lesions potentially leading to malignancy. Evolutionarily, obligatory pathogens such as HPVs would not be expected to risk exposing the host to lethal cancer, as this would entail challenging their own life cycle, but infection with these viruses is highly correlated with cancer and malignancy-as in cancer of the cervix, which is almost always associated with these viruses. Despite this key associative cause and the availability of very effective vaccines against these viruses, therapeutic interventions against HPV-induced cancers are still a challenge, indicating the need for focused translational research. In this review, we will consider the key roles that the viral proteins play in driving the host cells to carcinogenesis, mainly focusing on events orchestrated by early proteins E5, E6 and E7-the not-so-good, the bad and the ugly-and discuss and summarize the major events that lead to these viruses mechanistically corrupting cellular homeostasis, giving rise to cancer and malignancy.

Expression of the E5 Oncoprotein of HPV16 Impacts on the Molecular Profiles of EMT-Related and Differentiation Genes in Ectocervical Low-Grade Lesions

Infection with human papillomavirus type 16 (HPV16) is one of the major risk factors for the development of cervical cancer. Our previous studies have demonstrated the involvement of the early oncoprotein E5 of HPV16 (16E5) in the altered isoform switch of fibroblast growth factor receptor 2 (FGFR2) and the consequent expression in human keratinocytes of the mesenchymal FGFR2c isoform, whose aberrant signaling leads to EMT, invasiveness, and dysregulated differentiation. Here, we aimed to establish the possible direct link between these pathological features or the appearance of FGFR2c and the expression of 16E5 in low-grade squamous intraepithelial lesions (LSILs). Molecular analysis showed that the FGFR2c expression displayed a statistically significant positive correlation with that of the viral oncoprotein, whereas the expression values of the epithelial FGR2b variant, as well as those of the differentiation markers keratin 10 (K10), loricrin (LOR) and involucrin (INV), were inversely linked to the 16E5 expression. In contrast, the expression of EMT-related transcription factors Snail1 and ZEB1 overlapped with that of 16E5, becoming a statistically significant positive correlation in the case of Snail2. Parallel analysis performed in human cervical LSIL-derived W12 cells, containing episomal HPV16, revealed that the depletion of 16E5 by siRNA was able to counteract these molecular events, proving to represent an effective strategy to identify the specific role of this viral oncoprotein in determining LSIL oncogenic and more aggressive profiles. Overall, coupling in vitro approaches to the molecular transcript analysis in ectocervical early lesions could significantly contribute to the characterization of specific gene expression profiles prognostic for those LSILs with a greater probability of direct neoplastic progression.

Expression Analysis of FGF/FGFR and FOX Family Proteins in Mucosal Tissue Obtained from Orofacial Cleft-Affected Children

Orofacial clefts affect hundreds of thousands of children worldwide annually and are usually corrected by a series of surgeries extending to childhood. The underlying mechanisms that lead to clefts are still unknown, mainly because of the multifactorial etiology and the myriad of interactions between genes and environmental factors. In the present study, we investigated the role and expression of candidate genes belonging to the FGF/FGFR signaling pathway and FOX family in tissue material obtained from 12 pediatric patients undergoing cleft correction surgery. The expression was investigated using immunohistochemistry (IHC) and chromogenic in-situ hybridization (CISH) in three cell/tissue types-epithelial cells, connective tissue, and endothelial cells. We found elevated expression of FGFR1 in epithelial cells while no expression was observed in endothelial cells. Further, our results elucidate the potential pathogenetic role of FGFR1 in cellular proliferation, local site inflammation, and fibrosis in cleft patients. Along with bFGF (also called FGF2), FGFR1 could play a pro-inflammatory role in clefts. Over-amplification of FGFR2 in some patients, along with bFGF, could potentially suggest roles for these genes in angiogenesis. Additionally, increased expression of FOXE1 (also called TTF2) contributes to local site inflammation. Finally, zero to low amplification of FOXO1 could suggest its potential role in inducing oxidative stress in the endothelium along with reduced epithelial apoptosis.

2b or Not 2b: How Opposing FGF Receptor Splice Variants Are Blocking Progress in Precision Oncology

More than ten thousand peer-reviewed studies have assessed the role of fibroblast growth factors (FGFs) and their receptors (FGFRs) in cancer, but few patients have yet benefited from drugs targeting this molecular family. Strategizing how best to use FGFR-targeted drugs is complicated by multiple variables, including RNA splicing events that alter the affinity of ligands for FGFRs and hence change the outcomes of stromal-epithelial interactions. The effects of splicing are most relevant to FGFR2; expression of the FGFR2b splice isoform can restore apoptotic sensitivity to cancer cells, whereas switching to FGFR2c may drive tumor progression by triggering epithelial-mesenchymal transition. The differentiating and regulatory actions of wild-type FGFR2b contrast with the proliferative actions of FGFR1 and FGFR3, and may be converted to mitogenicity either by splice switching or by silencing of tumor suppressor genes such as CDH1 or PTEN. Exclusive use of small-molecule pan-FGFR inhibitors may thus cause nonselective blockade of FGFR2 isoforms with opposing actions, undermining the rationale of FGFR2 drug targeting. This splice-dependent ability of FGFR2 to switch between tumor-suppressing and -driving functions highlights an unmet oncologic need for isoform-specific drug targeting, e.g., by antibody inhibition of ligand-FGFR2c binding, as well as for more nuanced molecular pathology prediction of FGFR2 actions in different stromal-tumor contexts.

Expression Profile of Fibroblast Growth Factor Receptors, Keratinocyte Differentiation Markers, and Epithelial Mesenchymal Transition-Related Genes in Actinic Keratosis: A Possible Predictive Factor for Malignant Progression?

Simple Summary

In this work, we checked the modulation of Fibroblast Growth Factor Receptors (FGFRs) along with differentiation-related and epithelial-to-mesenchymal transition (EMT)-related markers to identify expression profiles that could be predictive for actinic keratosis (AK) progression through the “differentiated” pathway. We found that the downregulation of the analyzed differentiation markers, but not the modulation of the EMT-related markers, correlated with the canonical progression of AK. In addition, the observed modulation of FGFR2 mesenchymal/epithelial isoforms compatible with FGFR2 isoform switch, as well as the upregulation of FGFR4 suggested their correlation with early steps of AK pathogenesis. In contrast, the increase of mesenchymal FGFR3c isoform expression appeared to suggest that this event correlated with late steps of AK progression. In addition, the strong modulation of filaggrin (FIL), Snail1, as well as of FGFR2c, FGFR4, and their ligand Fibroblast Growth Factor 2 (FGF2), observed in some of the keratinocytic intraepithelial neoplasia grade I (KIN I) samples, may indicate that they could be molecular markers predictive for those KIN I lesions destined to a direct progression to squamous cell carcinoma (SCC) through the “differentiated” pathway.

Abstract

Actinic keratosis (AK) is the ultra violet (UV)-induced preneoplastic skin lesion clinically classified in low (KIN I), intermediate (KIN II), and high (KIN III) grade lesions. In this work we analyzed the expression of Fibroblast Growth Factor Receptors (FGFRs), as well as of keratinocyte differentiation and epithelial-to-mesenchymal transition (EMT)-related markers in differentially graded AK lesions, in order to identify specific expression profiles that could be predictive for direct progression of some KIN I lesions towards squamous cell carcinoma (SCC). Our molecular analysis showed that the keratinocyte differentiation markers keratin 1 (K1), desmoglein-1 (DSG1), and filaggrin (FIL) were progressively downregulated in KIN I, II, and III lesions, while the modulation of epithelial/mesenchymal markers and the induction of the transcription factors Snail1 and Zinc finger E-box-binding homeobox 1 (ZEB1) compatible with pathological EMT, even if observable, did not appear to correlate with AK progression. Concerning FGFRs, a modulation of epithelial isoform of FGFR2 (FGFR2b) and the mesenchymal FGFR2c isoform compatible with an FGFR2 isoform switch, as well as FGFR4 upregulation were observed starting from KIN I lesions, suggesting that they could be events involved in early steps of AK pathogenesis. In contrast, the increase of FGFR3c expression, mainly appreciable in KIN II and KIN III lesions, suggested a correlation with AK late progression. Interestingly, the strong modulation of FIL, Snail1, as well as of FGFR2c, FGFR4, and of their ligand FGF2, observed in some of the KIN I samples, may indicate that they could be molecular markers predictive for those low graded lesions destined to a direct progression to SCC. In conclusion, our data point on the identification of molecular markers predictive for AK rapid progression through the “differentiated” pathway. Our results also represent an important step that, in future, will help to clarify the molecular mechanisms underlying FGFR signaling deregulation in epithelial tissues during the switch from the pre-neoplastic to the oncogenic malignant phenotype.

The human papillomavirus oncoproteins: a review of the host pathways targeted on the road to transformation

Persistent infection with high-risk human papillomaviruses (HR-HPVs) is the causal factor in over 99 % of cervical cancer cases, and a significant proportion of oropharyngeal and anogenital cancers. The key drivers of HPV-mediated transformation are the oncoproteins E5, E6 and E7. Together, they act to prolong cell-cycle progression, delay differentiation and inhibit apoptosis in the host keratinocyte cell in order to generate an environment permissive for viral replication. The oncoproteins also have key roles in mediating evasion of the host immune response, enabling infection to persist. Moreover, prolonged infection within the cellular environment established by the HR-HPV oncoproteins can lead to the acquisition of host genetic mutations, eventually culminating in transformation to malignancy. In this review, we outline the many ways in which the HR-HPV oncoproteins manipulate the host cellular environment, focusing on how these activities can contribute to carcinogenesis.

Alternative splicing modulates cancer aggressiveness: role in EMT/metastasis and chemoresistance

Enhanced metastasis and disease recurrence accounts for the high mortality rates associated with cancer. The process of Epithelial-Mesenchymal Transition (EMT) contributes towards the augmentation of cancer invasiveness along with the gain of stem-like and the subsequent drug-resistant behavior. Apart from the well-established transcriptional regulation, EMT is also controlled post-transcriptionally by virtue of alternative splicing (AS). Numerous genes including Fibroblast Growth Factor receptor (FGFR) as well as CD44 are differentially spliced during this trans-differentiation process which, in turn, governs cancer progression. These splicing alterations are controlled by various splicing factors including ESRP, RBFOX2 as well as hnRNPs. Here, we have depicted the mechanisms governing the splice isoform switching of FGFR and CD44. Moreover, the role of the splice variants generated by AS of these gene transcripts in modulating the metastatic potential and stem-like/chemoresistant behavior of cancer cells has also been highlighted. Additionally, the involvement of splicing factors in regulating EMT/invasiveness along with drug-resistance as well as the metabolic properties of the cells has been emphasized. Tumorigenesis is accompanied by a remodeling of the cellular splicing profile generating diverse protein isoforms which, in turn, control the cancer-associated hallmarks. Therefore, we have also briefly discussed about a wide variety of genes which are differentially spliced in the tumor cells and promote cancer progression. We have also outlined different strategies for targeting the tumor-associated splicing events which have shown promising results and therefore this approach might be useful in developing therapies to reduce cancer aggressiveness in a more specific manner.

Fibroblast growth factor receptor signaling as therapeutic targets in female reproductive system cancers

Ovarian cancer, cervical cancer and endometrial cancer are three relatively common malignant cancers of the female reproductive system. Despite improvements in female genital tract cancer detection and development of new therapeutic approaches, there are still poor prognoses and some do not respond to therapeutic patterns, displaying low survival and high frequency of recurrence. In an era of personalized medicine, novel therapeutic approaches with greater efficacy for these cancers represent an unmet need. One of the actionable signaling pathways is the fibroblast growth factor receptor (FGFR) signaling pathway. Several mutations and alterations in FGF/FGFR family members have been reported in human cancers. FGF/FGFR signaling pathway has become a new target for cancer therapy. This review will summarize the role of FGFR pathway and the genetic alterations of the FGF/FGFR related to female reproductive system cancer. We will describe the available inhibitors of FGFR pathway for potential treatment of female reproductive system cancer. Furthermore, we will discuss FGFR-targeted therapies under clinical development for treatment of female reproductive system cancer.

HPV E2, E4, E5 drive alternative carcinogenic pathways in HPV positive cancers

The dominant paradigm for HPV carcinogenesis includes integration into the host genome followed by expression of E6 and E7 (E6/E7). We explored an alternative carcinogenic pathway characterized by episomal E2, E4, and E5 (E2/E4/E5) expression. Half of HPV positive cervical and pharyngeal cancers comprised a subtype with increase in expression of E2/E4/E5, as well as association with lack of integration into the host genome. Models of the E2/E4/E5 carcinogenesis show p53 dependent enhanced proliferation in vitro, as well as increased susceptibility to induction of cancer in vivo. Whole genomic expression analysis of the E2/E4/E5 pharyngeal cancer subtype is defined by activation of the fibroblast growth factor receptor (FGFR) pathway and this subtype is susceptible to combination FGFR and mTOR inhibition, with implications for targeted therapy.

Role of PKCε in the epithelial-mesenchymal transition induced by FGFR2 isoform switch

Background

The epithelial isoform of the fibroblast growth factor receptor 2 (FGFR2b) controls the entire program of keratinocyte differentiation via the sequential involvement of protein kinase C (PKC) δ and PKCα. In contrast, the FGFR2 isoform switch and the aberrant expression of the mesenchymal FGFR2c isoform leads to impairment of differentiation, epithelial-mesenchymal transition (EMT) and tumorigenic features. Aim of our present study was to contribute in clarifying the complex network of signaling pathways involved in the FGFR2c-mediated oncogenic outcomes focusing on PKCε, which appears to be involved in the induction of EMT and tumorigenesis in several epithelial contexts.

Methods

Biochemical and molecular analysis, as well as in vitro invasion assays, combined with the use of specific small interfering RNA (siRNA), were performed in human keratinocytes stably expressing FGFR2c or FGFR2b isoforms.

Results

Our results showed that aberrant expression and signaling of FGFR2c, but not those of FGFR2b, in human keratinocytes induced a strong phosphorylation/activation of PKCε. The use of siRNA approach showed that PKCε is the hub signaling downstream FGFR2c responsible for the modulation of EMT markers and for the induction of the EMT-related transcription factors STAT3, Snail1 and FRA1, as well as for the acquisition of the invasive behavior. Moreover, experiments of depletion of ESRP1, responsible for FGFR2 splicing in epithelial cells, indicated that the activation of PKCε is the key molecular event triggered by FGFR2 isoform switch and underlying EMT induction.

Conclusions

Overall, our results point to the identification of the downstream PKC isoform responsible for the FGFR signaling deregulation occurring in epithelial tissues from the physiological oncosoppressive to the pathological oncogenic profile.

Prognostic value of epithelial-mesenchymal transition-inducing transcription factors in head and neck squamous cell carcinoma: A meta-analysis

Epithelial-mesenchymal transition (EMT) plays a critical role in cancer progression and is primarily regulated by several EMT-inducing transcription factors (EMT-TFs), including TWIST1, TWIST2, SNAI1, SNAI2, ZEB1, and ZEB2. However, the prognostic value of EMT-TFs remains controversial in head and neck squamous cell carcinoma (HNSCC). Studies on the prognostic role of EMT-TFs in HNSCC were searched for in the Web of Science, Science Direct, Proquest, EMBASE, PubMed, and Cochrane Library. Meta-analysis was performed by using Revman 5.2 software. The pooled analysis showed that overexpression of EMT-TFs indicated a poor overall survival (OS) (HR = 1.93, 95% CI = 1.67-2.23) of HNSCC. Subgroup analysis for individual EMT-TFs revealed that overexpression of TWIST1 (HR = 1.61, 95% CI = 1.29-2.02), SNAI1 (HR = 2.17, 95% CI = 1.63-2.88), SNAI2 (HR = 1.90, 95% CI = 1.38-2.62), and ZEB1 (HR = 2.70, 95% CI = 1.61-4.53) were significantly associated with poor OS of HNSCC. These findings support the hypothesis that overexpression of EMT-TFs indicates a poor prognosis for HNSCC patients.

HPV16 E5 Mediates Resistance to PD-L1 Blockade and Can Be Targeted with Rimantadine in Head and Neck Cancer

There is a critical need to understand mechanisms of resistance and to develop combinatorial strategies to improve responses to checkpoint blockade immunotherapy (CBI). Here, we uncover a novel mechanism by which the human papillomavirus (HPV) inhibits the activity of CBI in head and neck squamous cell carcinoma (HNSCC). Using orthotopic HNSCC models, we show that radiation combined with anti-PD-L1 immunotherapy significantly enhanced local control, CD8⁺ memory T cells, and induced preferential T-cell homing via modulation of vascular endothelial cells. However, the HPV E5 oncoprotein suppressed immune responses by downregulating expression of major histocompatibility complex and interfering with antigen presentation in murine models and patient tumors. Furthermore, tumors expressing HPV E5 were rendered entirely resistant to anti-PD-L1 immunotherapy, and patients with high expression of HPV16 E5 had worse survival. The antiviral E5 inhibitor rimantadine demonstrated remarkable single-agent antitumor activity. This is the first report that describes HPV E5 as a mediator of resistance to anti-PD-1/PD-L1 immunotherapy and demonstrates the antitumor activity of rimantadine. These results have broad clinical relevance beyond HNSCC to other HPV-associated malignancies and reveal a powerful mechanism of HPV-mediated immunosuppression, which can be exploited to improve response rates to checkpoint blockade. SIGNIFICANCE: This study identifies a novel mechanism of resistance to anti-PD-1/PD-L1 immunotherapy mediated by HPV E5, which can be exploited using the HPV E5 inhibitor rimantadine to improve outcomes for head and neck cancer patients. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/4/732/F1.large.jpg.

The Aberrant Expression of the Mesenchymal Variant of FGFR2 in the Epithelial Context Inhibits Autophagy

Signaling of the epithelial splice variant of fibroblast growth factor receptor 2 (FGFR2b) triggers both differentiation and autophagy, while the aberrant expression of the mesenchymal FGFR2c isoform in epithelial cells induces impaired differentiation, epithelial mesenchymal transition (EMT) and tumorigenic features. Here we analyzed in the human keratinocyte cell line, as well as in primary cultured cells, the possible impact of FGFR2c forced expression on the autophagic process. Biochemical and quantitative immunofluorescence analysis, coupled to the use of autophagic flux sensors, specific substrate inhibitors or silencing approaches, showed that ectopic expression and the activation of FGFR2c inhibit the autophagosome formation and that AKT/MTOR is the downstream signaling mainly involved. Interestingly, the selective inhibition of AKT or MTOR substrates caused a reversion of the effects of FGFR2c on autophagy, which could also arise from the imbalance of the interplay between AKT/MTOR pathway and JNK1 signaling in favor of JNK1 activation, BCL-2 phosphorylation and possibly phagophore nucleation. Finally, silencing experiments of depletion of ESRP1, responsible for FGFR2 splicing and consequent FGFR2b expression, indicated that the switching from FGFR2b to FGFR2c isoform could represent the key event underlying the inhibition of the autophagic process in the epithelial context. Our results provide the first evidence of a negative impact of the out-of-context expression of FGFR2c on autophagy, suggesting a possible role of this receptor in the modulation of the recently proposed negative loop between autophagy and EMT during carcinogenesis.

Human Papillomavirus 16 Oncoproteins Downregulate the Expression of miR-148a-3p, miR-190a-5p, and miR-199b-5p in Cervical Cancer

Almost all cervical cancers are associated with human papillomavirus (HPV); however, the majority of women infected with this virus do not develop cervical cancer. Therefore, new markers are needed for reliable screening of cervical cancer, especially in relation to HPV infection. We aimed to identify potential microRNAs that may serve as diagnostic markers for cervical cancer development in high-risk HPV-positive patients. We evaluated the microRNA expression profiles in 12 cervical tissues using the hybridization method and verified them by quantitative polymerase chain reaction (qPCR). Finally, we evaluated the effects of HPV16 oncoproteins on the expression of selected microRNAs using cervical cancer cells (CaSki and SiHa) and RNA interference. With the hybridization method, eight microRNAs (miR-9-5p, miR-136-5p, miR-148a-3p, miR-190a-5p, miR-199b-5p, miR-382-5p, miR-597-5p, and miR-655-3p) were found to be expressed differently in the HPV16-positive cervical cancer group and HPV16-positive normal group (fold change ≥ 2). The results of qPCR showed that miR-148a-3p, miR-190a-5p, miR-199b-5p, and miR-655-3p levels significantly decreased in the cancer group compared with the normal group. Upon silencing of HPV16 E5 and E6/E7, miR-148a-3p levels increased in both cell lines. Silencing of E6/E7 in SiHa cells led to the increase in miR-199b-5p and miR-190a-5p levels. Three HPV16 oncoproteins (E5, E6, and E7) downregulate miR-148a-3p, while E6/E7 inhibit miR-199b-5p and miR-190a-5p expression in cervical carcinoma. The three microRNAs, miR-148a-3p, miR-199b-5p, and miR-190a-5p, may be novel diagnostic biomarkers for cervical cancer development in high-risk HPV-positive patients.

Activities of stromal and immune cells in HPV-related cancers

The immune system is composed of immune as well as non-immune cells. As this system is a well-established component of human papillomavirus- (HPV)-related carcinogenesis, high risk human papillomavirus (hrHPV) prevents its routes and mechanisms in order to cause the persistence of infection. Among these mechanisms are those originated from stromal cells, which include the cancer-associated fibroblasts (CAFs), the myeloid-derived suppressor cells (MDSCs) and the host infected cells themselves, i.e. the keratinocytes. These types of cells play central role since they modulate immune cells activities to create a prosperous milieu for cancer development, and the knowledge how such interactions occur are essential for prognostic assessment and development of preventive and therapeutic approaches. Nevertheless, the precise mechanisms are not completely understood, and this lack of knowledge precluded the development of entirely efficient immunotherapeutic strategies for HPV-associated tumors. As a result, an intense work for attaining how host immune response works, and developing of effective therapies has been applied in the last decade. Based on this, this review aims to discuss the major mechanisms of immune and non-immune cells modulated by hrHPV and the potential and existing immunotherapies involving such mechanisms in HPV-related cancers. It is noticed that the combination of immunotherapies has been demonstrated to be essential for obtaining better results, especially because the possibility of increasing the modulating capacity of the HPV-tumor microenvironment has been shown to be central in strengthening the host immune system.

Development of Novel Single-Chain Antibodies against the Hydrophobic HPV-16 E5 Protein

The human papilloma virus type 16 infects genital mucosa with high prevalence in the oncogenesis of cervical and oropharyngeal cancers. The E5 protein of this virus is a small hydrophobic protein, whose expression generally decreases as the infection progresses to malignancy. These characteristics point to a role of E5 in the establishment of HPV infection and the initiation into cell transformation. The study of the HPV-16 E5 functions has been hindered because of the lack of antibodies. Detection is very difficult because of its hydrophobic nature, membrane location, and very low levels of expression. Thus, the objective of this study was to select single-chain antibodies against the full size E5 protein, which was coexpressed with maltose-binding protein. We report that the E5 protein was recognized by the antibody and was validated in W12 cells by fluorescent microscopy, including a colocalization with one of its host substrates. The use of this antibody could increase our knowledge about the functions of the oncogenic HPV-16 E5 protein during the earliest stages of keratinocyte infection in human.

Epstein-Barr Virus and Human Papillomaviruses Interactions and Their Roles in the Initiation of Epithelial-Mesenchymal Transition and Cancer Progression

Oncoviruses are implicated in around 20% of all human cancers including both solid and non-solid malignancies. Epstein–Barr virus (EBV) and human papillomaviruses (HPVs) are the most common oncoviruses worldwide. Currently, it is well established that onco-proteins of EBV (LMP1, LMP2A, and EBNA1) and high-risk HPVs (E5 and E6/E7) play an important role in the initiation and/or progression of several human carcinomas, including cervical, oral, and breast. More significantly, it has been recently pointed out that viral onco-proteins of EBV and high-risk HPVs can be co-present and consequently cooperate to initiate and/or amplify epithelial–mesenchymal transition (EMT), which is the hallmark of cancer progression and metastasis. This could occur by β-catenin, JAK/STAT/SRC, PI3k/Akt/mTOR, and/or RAS/MEK/ERK signaling pathways, which onco-proteins of EBV and HPVs share. This review presents the most recent advances related to EBV and high-risk HPVs onco-proteins interactions and their roles in the progression of human carcinomas especially oral and breast via the initiation of EMT.

Role of FGFR2b expression and signaling in keratinocyte differentiation: sequential involvement of PKCδ and PKCα

The tumor suppressor epithelial isoform of the fibroblast growth factor receptor 2 (FGFR2b) induces human keratinocyte early differentiation. Moreover, protein kinases C (PKCs) are known to regulate the differentiation program in several cellular contexts, including keratinocytes. Therefore, in this paper we propose to clarify if FGFR2b could play a role also in the late steps of keratinocyte differentiation and to assess if this receptor-induced process would sequentially involve PKCδ and PKCα isoforms. Immunofluorescence, biochemical, and molecular approaches, performed on 2D cultures or 3D organotypic rafts of human keratinocytes overexpressing FGFR2b by stable transduction, showed that receptor signaling induced the precocious onset and an accelerated progression of keratinocyte differentiation, indicating that FGFR2b is a crucial regulator of the entire program of keratinocyte differentiation. In addition, the use of specific inhibitors and gene silencing approaches through specific siRNA demonstrated that PKCδ controls the onset of FGFR2b-triggered differentiation, while PKCα plays a role restricted to the terminal stages of the process. Molecular analysis revealed that the two PKC isoforms sequentially act via induction of KLF4 and DLX3, two transcription factors linked by negative loops to p63, suggesting that p63 would represent the hub molecule at the crossroad of an intricate signaling network downstream FGFR2b, involving multiple PKC-induced transcription factors.

Glucose tolerance in obese men is associated with dysregulation of some angiogenesis-related gene expressions in subcutaneous adipose tissue

Obesity and its metabolic complications are one of the most profound public health problems and result from interactions between genes and environmental. The development of obesity is tightly connected with dysregulation of intrinsic gene expression mechanisms controlling majority of metabolic processes, which are essential for regulation many physiological functions, including insulin sensitivity, cellular proliferation and angiogenesis. Our objective was to evaluate if expression of angiogenesis related genes VEGF-A, CYR61, PDGFC, FGF1, FGF2, FGFR2, FGFRL1, E2F8, BAI2, HIF1A, and EPAS1 at mRNA level in adipose tissue could participate in the development of obesity and metabolic complications. We have shown that expression level of VEGF-A, PDGFC, FGF2, and FGFRL1 genes is decreased in adipose tissue of obese men with normal glucose tolerance (NGT) versus a group of control subjects. At the same time, in this group of obese individuals a significant up-regulation of CYR61, FGF1, FGFR2, E2F8, BAI2, and HIF1A gene expressions was observed. Impaired glucose tolerance (IGT) in obese patients associates with down-regulation of CYR61 and FGFR2 mRNA and up-regulations of E2F8, FGF1, FGF2, VEGF-A and its splice variant 189 mRNA expressions in adipose tissue versus obese (NGT) individuals. Thus, our data demonstrate that the expression of almost all studied genes is affected in subcutaneous adipose tissue of obese individuals with NGT and that glucose intolerance is associated with gene-specific changes in the expression of E2F8, FGF1, FGF2, VEGF-A, CYR61 and FGFR2 mRNAs. The data presented here provides evidence that VEGF-A, CYR61, PDGFC, FGF1, FGF2, FGFR2, FGFRL1, E2F8, BAI2, and HIF1A genes are possibly involved in the development of obesity and its complications.

Expression of the FGFR2c mesenchymal splicing variant in human keratinocytes inhibits differentiation and promotes invasion

The altered isoform switching of the fibroblast growth factor receptor 2 (FGFR2) and aberrant expression of the mesenchymal FGFR2c isoform in epithelial cells is involved in cancer progression. We have recently described that the ectopic expression of FGFR2c in normal human keratinocytes induces epithelial‐mesenchymal transition and leads to invasiveness and anchorage‐independent growth. Here, we extended our analysis to the effects of this FGFR2c forced expression on human keratinocyte differentiation and stratification. Our findings demonstrated that, differently from cells overexpressing the epithelial splicing variant FGFR2b, keratinocytes ectopically expressing FGFR2c are not able to form a monolayer and display decreased expression of early differentiation markers. This impaired ability to enter the differentiation program is related to the up‐modulation of the transcription factor ΔNp63. In addition, FGFR2c‐expressing keratinocytes undergo defective stratification and invasion of the collagen matrix in 3D organotypic cultures, further suggesting their tumorigenic potential. Taken together, our results support the hypothesis that the receptor switching and the consequent appearance of the mesenchymal FGFR2c variant in the epithelial context would drive early steps of carcinogenesis, unbalancing the p63/FGFR interplay, and altering the paracrine response to the microenvironment.

Advances and challenges in targeting FGFR signalling in cancer

Fibroblast growth factors (FGFs) and their receptors (FGFRs) regulate numerous cellular processes. Deregulation of FGFR signalling is observed in a subset of many cancers, making activated FGFRs a highly promising potential therapeutic target supported by multiple preclinical studies. However, early-phase clinical trials have produced mixed results with FGFR-targeted cancer therapies, revealing substantial complexity to targeting aberrant FGFR signalling. In this Review, we discuss the increasing understanding of the differences between diverse mechanisms of oncogenic activation of FGFR, and the factors that determine response and resistance to FGFR targeting.

Simulated microgravity triggers epithelial mesenchymal transition in human keratinocytes

The microgravitational environment is known to affect the cellular behaviour inducing modulation of gene expression and enzymatic activities, epigenetic modifications and alterations of the structural organization. Simulated microgravity, obtained in the laboratory setting through the use of a Random Positioning Machine (RPM), represents a well recognized and useful tool for the experimental studies of the cellular adaptations and molecular changes in response to weightlessness. Short exposure of cultured human keratinocytes to the RPM microgravity influences the cellular circadian clock oscillation. Therefore, here we searched for changes on the regenerative ability and response to tissue damage of human epidermal cells through the analysis of the effects of the simulated microgravity on the re-epithelialization phase of the repair and wound healing process. Combining morphological, biochemical and molecular approaches, we found that the simulated microgravity exposure of human keratinocytes promotes a migratory behavior and triggers the epithelial-mesenchymal transition (EMT) through expression of the typical EMT transcription factors and markers, such as Snail1, Snail2 and ZEB2, metalloproteases, mesenchymal adhesion molecules and cytoskeletal components.

Epithelial to mesenchymal transition and HPV infection in squamous cell oropharyngeal carcinomas: the papillophar study

Background:

Human Papillomavirus (HPV) infection is recognised as aetiological factor of carcinogenesis in oropharyngeal squamous cell carcinomas (OPC). HPV-related OPC respond better to treatments and have a significantly favourable outcome. Epithelial to mesenchymal transition (EMT) implicated in tumour invasion, is a hallmark of a poor prognosis in carcinomas.

Methods:

We have studied the relationship of EMT markers (E-cadherin, β-catenin and vimentin) with HPV infection (DNA and E6/E7 mRNA detection), p16^INK4a expression and survival outcomes in a cohort of 296 patients with OPC.

Results:

Among the 296 OPSSC, 26% were HPV positive, 20.3% had overt EMT (>25% of vimentin positive tumour cells). Lower E-cadherin expression was associated with a higher risk of distant metastasis in univariate (P=0.0110) and multivariate analyses (hazard ratios (HR)=6.86 (1.98; 23.84)). Vimentin expression tends towards worse metastasis-free survival (MFS; HR=2.53 (1.00; 6.41)) and was an independent prognostic factor of progression-free survival (HR=1.55 (1.03; 2.34)).

Conclusions:

There was a non significant association of EMT with HPV status. This may be explained by a mixed subpopulation of patients HPV positive with associated risk factors (HPV, tobacco and alcohol). Thus, the detection of EMT in OPC represents another reliable approach in the prognosis and the management of OPC whatever their HPV status.

Overexpression of Human Papillomavirus Type 16 Oncoproteins Enhances Epithelial-Mesenchymal Transition via STAT3 Signaling Pathway in Non-Small Cell Lung Cancer Cells

The human papillomavirus (HPV) infection may be associated with the development and progression of non-small cell lung cancer (NSCLC). However, the role of HPV-16 oncoproteins in the development and progression of NSCLC is not completely clear. Epithelial–mesenchymal transition (EMT), a crucial step for invasion and metastasis, plays a key role in the development and progression of NSCLC. Here we explored the effect of HPV-16 oncoproteins on EMT and the underlying mechanisms. NSCLC cell lines, A549 and NCI-H460, were transiently transfected with the EGFP-N1-HPV-16 E6 or E7 plasmid. Real-time PCR and Western blot analysis were performed to analyze the expression of EMT markers. A protein microarray was used to screen the involved signaling pathway. Our results showed that overexpression of HPV-16 E6 and E7 oncoproteins in NSCLC cells significantly promoted EMT-like morphologic changes, downregulated the mRNA and protein levels of EMT epithelial markers (E-cadherin and ZO-1), and upregulated the mRNA and protein levels of EMT mesenchymal markers (N-cadherin and vimentin) and transcription factors (ZEB-1 and Snail-1). Furthermore, the HPV-16 E6 oncoprotein promoted STAT3 activation. Moreover, WP1066, a specific signal transducer and activator of transcription 3 (STAT3) inhibitor, reversed the effect of HPV-16 E6 on the expression of ZO-1, vimentin, and ZEB-1 in transfected NSCLC cells. Taken together, our results suggest that overexpression of HPV-16 E6 and E7 oncoproteins enhances EMT, and the STAT3 signaling pathway may be involved in HPV-16 E6-induced EMT in NSCLC cells.

Expression of the FGFR2 mesenchymal splicing variant in epithelial cells drives epithelial-mesenchymal transition

The FGFRs are receptor tyrosine kinases expressed by tissue-specific alternative splicing in epithelial IIIb or mesenchymal IIIc isoforms. Deregulation of FGF/FGFR signaling unbalances the epithelial-stromal homeostasis and may lead to cancer development. In the epithelial-context, while FGFR2b/KGFR acts as tumor suppressor, FGFR2c appears to play an oncogenic role. Based on our recent observation that the switching of FGFR2b versus FGFR2c induces EMT, here we investigated the biological outcome of the ectopic expression of FGFR2c in normal human keratinocytes. Morphological analysis showed that, differently from FGFR2b overexpression, the forced expression and activation of FGFR2c drive the epithelial cells to acquire a mesenchymal-like shape and actin reorganization. Moreover, the appearance of invasiveness and anchorage-independent growth ability in FGFR2c transfected keratinocytes was consistent with the potential tumorigenic role proposed for this receptor variant. Biochemical and molecular approaches revealed that the observed phenotypic changes were accompanied by modulation of EMT biomarkers and indicated the involvement of EMT transcription factors and miRs. Finally, the analysis of the expression pattern of discriminating markers strongly suggested that activation of FGFR2c triggers a process corresponding to the initiation of the pathological type III EMT, but not to the more physiological type II EMT occurring during FGFR2b-mediated wound healing.

Aberrant Splicing in Cancer: Mediators of Malignant Progression through an Imperfect Splice Program Shift

Although the efforts to understand the genetic basis of cancer allowed advances in diagnosis and therapy, little is known about other molecular bases. Splicing is a key event in gene expression, controlling the excision of introns decoded inside genes and being responsible for 80% of the proteome amplification through events of alternative splicing. Growing data from the last decade point to deregulation of splicing events as crucial in carcinogenesis and tumor progression. Several alterations in splicing events were observed in cancer, caused by either missexpression of or detrimental mutations in some splicing factors, and appear to be critical in carcinogenesis and key events during tumor progression. Notwithstanding, it is difficult to determine whether it is a cause or consequence of cancer and/or tumorigenesis. Most reviews focus on the generated isoforms of deregulated splicing pattern, while others mainly summarize deregulated splicing factors observed in cancer. In this review, events associated with carcinogenesis and tumor progression mainly, and epithelial-to-mesenchymal transition, which is also implicated in alternative splicing regulation, will be progressively discussed in the light of a new perspective, suggesting that splicing deregulation mediates cell reprogramming in tumor progression by an imperfect shift of the splice program.

EGFR-Based Immunoisolation as a Recovery Target for Low-EpCAM CTC Subpopulation

Circulating tumour cells (CTCs) play a key role in the metastasis process, as they are responsible for micrometastasis and are a valuable tool for monitoring patients in real-time. Moreover, efforts to develop new strategies for CTCs isolation and characterisation, and the translation of CTCs into clinical practice needs to overcome the limitation associated with the sole use of Epithelial Cell Adhesion Molecule (EpCAM) expression to purify this tumour cell subpopulation. CTCs are rare events in the blood of patients and are believed to represent the epithelial population from a primary tumour of epithelial origin, thus EpCAM immunoisolation is considered an appropriate strategy. The controversy stems from the impact that the more aggressive mesenchymal tumour phenotypes might have on the whole CTC population. In this work, we first characterised a panel of cell lines representative of tumour heterogeneity, confirming the existence of tumour cell subpopulations with restricted epithelial features and supporting the limitations of EpCAM-based technologies. We next developed customised polystyrene magnetic beads coated with antibodies to efficiently isolate the phenotypically different subpopulations of CTCs from the peripheral blood mononuclear cells (PBMCs) of patients with metastatic cancer. Besides EpCAM, we propose Epidermal Growth Factor Receptor (EGFR) as an additional isolation marker for efficient CTCs detection.

Roles and Regulation of Epithelial Splicing Regulatory Proteins 1 and 2 in Epithelial-Mesenchymal Transition

The transformation of polarized epithelial cells into cells with mesenchymal characteristics by the morphogenetic process of epithelial-mesenchymal transition (EMT) is a well-characterized process essential for embryonic development and associated with cancer progression. EMT is a program driven by changes in gene expression induced by several EMT-specific transcription factors, which inhibit the expression of cell-cell adhesion proteins and other epithelial markers, causing a characteristic loss of cell-cell adhesion, a switch to mesenchymal cell morphology, and increased migratory capabilities. Recently, it has become apparent that in addition to these transcriptionally regulated changes, EMT may also be regulated posttranscriptionally, that is, by alternative splicing. Specifically, the epithelial splicing regulatory proteins 1 and 2 (ESRP1 and ESRP2) have been described as epithelial-specific splicing master regulators specifically involved in EMT-associated alternative splicing. Here, we discuss the regulation of ESRP activity, as well as the evidence supporting a causal role of ESRPs in EMT.

Expression of fibroblast growth factor receptor family members is associated with prognosis in early stage cervical cancer patients

Background

The oncogenic role of the fibroblast growth factor receptor (FGFR) has been recognized in a number of different cancer types. However, the prognostic significance of FGFRs has not been elucidated yet in cervical cancer. In the present study, we investigate the expression of FGFRs and their prognostic value in cervical cancer patients.

Methods

FGFR1, FGFR2, FGFR3, and FGFR4 expression was determined by immunohistochemistry in conjunction with quantitative digital image analysis of 336 formalin-fixed, paraffin-embedded cervical cancer tissues and 61 normal cervical tissues, as well as NCI60 cell microarray. Subsequently, the association between clinicopathological characteristics and patient survival was assessed.

Results

FGFRs proteins were differentially expressed in the NCI60 cell line panel and showed considerable correlation between protein and mRNA expression. The expression of FGFR1, FGFR2, and FGFR4 were higher in cancer tissues than in normal tissues, whereas the expression of FGFR3 was higher in normal tissues. FGFR1 was highly expressed in adeno-/adenosquamous carcinoma (P = 0.020), while FGFR2, FGFR3, and FGFR4 expression were more prominent in squamous cell carcinoma (P < 0.001, P < 0.001, and P = 0.020, respectively). FGFR2 expression was significantly higher in small sized tumors (P = 0.020). Additionally, high FGFR2 and FGFR4 were correlated with negative lymph node metastasis (P = 0.048 and P = 0.040, respectively). FGFR1, FGFR2, and FGFR3 were highly expressed in tumors without parametrial involvement (P = 0.030, P = 0.005, and P = 0.010, respectively). In survival analysis, high expressions of FGFR2, FGFR3, and FGFR4 was associated with longer disease-free survival (P = 0.006, P = 0.035, P = 0.001, respectively) and overall survival (P = 0.003, P = 0.002, P = 0.003, respectively). Notably, the co-expression of all three FGFRs was significantly associated with favorable disease-free survival (P < 0.001) and overall survival (P < 0.001), compared to the negative expressions of the three FGFRs. The prognostic significance persisted in the cox regression analysis.

Conclusions

The frequent expression of members of the FGFR family in cervical cancer suggests they may have prognostic and therapeutic relevance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0874-0) contains supplementary material, which is available to authorized users.

Human papillomavirus 16 (HPV16) enhances tumor growth and cancer stemness of HPV-negative oral/oropharyngeal squamous cell carcinoma cells via miR-181 regulation

High-risk human papillomaviruses (e.g., HPV16, HPV18) are closely associated with the development of head and neck cancers including oral/oropharyngeal squamous cell carcinoma (OSCC). We previously demonstrated immortalization of normal human oral keratinocytes by introducing high-risk HPV whole genome, suggesting that HPV infection plays an important role in the early stage of oral carcinogenesis. Although HPV infection may occur in different stages of cancer development, roles of HPV in exacerbating malignant phenotypes in already-transformed cells in the context of cancer stemness are not clearly defined. In this study, we investigated the role of HPV16 in promoting the virulence of HPV-negative OSCC. Introducing HPV16 whole genome in HPV-negative OSCC increased malignant growth and self-renewal capacity, a key characteristic of cancer stem cells (CSCs). HPV16 also enhanced other CSC properties, including aldehyde dehydrogenase 1 (ALDH1) activity, migration/invasion, and CSC-related factor expression. Mechanistically, we found that HPV16 inhibited the expression of miR-181a and miR-181d (miR-181a/d) at the transcriptional level. Ectopic expression of miR-181a/d decreased anchorage independent growth and CSC phenotype of HPV16-transfected OSCC. Furthermore, silencing of miR-181a/d target genes, i.e., K-ras and ALDH1, abrogated the effects of HPV16 in HPV16-transfected OSCC, supporting the functional importance of HPV16/miR-181a/d axis in HPV-mediated oral carcinogenesis. Our study suggests that high-risk HPV infection further promotes malignancy in HPV-negative OSCC by enhancing cancer stemness via miR-181a/d regulation. Consequently, miR-181a/d may represent a novel therapeutic agent for the treatment of HPV-positive OSCC.

E5 and E6/E7 of high-risk HPVs cooperate to enhance cancer progression through EMT initiation

It is estimated that 10-20% of human carcinogenesis is linked to virus infection including papillomaviruses (HPVs). Moreover, since metastatic cancer disease is a major cause of morbidity and mortality in cancer patients, the role of onco-viruses in cancer progression to a metastatic form is of particular interest. Recent studies reported that E5 and E6/E7 onco-proteins of high-risk HPVs could enhance cancer progression via the initiation of the epithelial-mesenchymal transition (EMT) event. Herein, we discuss the association between E5 as well as E6/E7 of high-risk HPV and cancer progression.