Tumor-Intrinsic Perinuclear LOXL2: Prognostic Relevance and Relationship with YAP1 Activation Status in Oral Squamous Cell Carcinoma.

INTRODUCTION: Lysyl oxidase-like 2 (LOXL2) expression and function is frequently altered in different cancers but scarcely explored in oral squamous cell carcinoma (OSCC). This prompted us to investigate the clinical relevance of LOXL2 expression pattern in OSCC and also a possible crosstalk with Hippo/YAP1 pathway signaling. METHODS: Immunohistochemical analysis of LOXL2 protein expression was performed in 158 OSCC patient samples, together with Yes-associated protein 1 (YAP1) activation status. Correlations with clinicopathological parameters and patient survival were assessed. RESULTS: Tumor cell-intrinsic LOXL2 expression showed two distinct expression patterns: diffuse cytoplasmic staining (64.6%) and heterogeneous perinuclear staining (35.4%). Remarkably, perinuclear LOXL2 staining was significantly associated with lymph node metastasis, advanced clinical stage and perineural invasion. Moreover, patients harboring tumors with perinuclear LOXL2 expression exhibited significantly poorer disease-specific survival (DSS) rates, and perinuclear LOXL2 positivity gradually increased in relation to YAP1 activation. Patients harboring tumors with concomitant perinuclear LOXL2 and fully active YAP1 exhibited the worst DSS. Multivariate Cox analysis further revealed combined perinuclear LOXL2 and fully active YAP1 as a significant independent predictor of poor DSS. CONCLUSION: Tumor-intrinsic perinuclear LOXL2 emerges as a clinically and biologically relevant feature associated with advanced disease, tumor aggressiveness, and poor prognosis in OSCC. Moreover, this study unprecedentedly uncovers a functional relationship between perinuclear LOXL2 and YAP1 activation with major prognostic implications. Notably, combined perinuclear LOXL2 and fully active YAP1 was revealed as independent predictor of poor prognosis. These findings encourage targeting oncogenic LOXL2 functions for personalized treatment regimens.

eEF2K Activity Determines Synergy to Cotreatment of Cancer Cells With PI3K and MEK Inhibitors.

PI3K-mammalian target of rapamycin and MAPK/ERK kinase (MEK)/mitogen-activated protein kinase (MAPK) are the most frequently dysregulated signaling pathways in cancer. A problem that limits the success of therapies that target individual PI3K-MAPK members is that these pathways converge to regulate downstream functions and often compensate each other, leading to drug resistance and transient responses to therapy. In order to overcome resistance, therapies based on cotreatments with PI3K/AKT and MEK/MAPK inhibitors are now being investigated in clinical trials, but the mechanisms of sensitivity to cotreatment are not fully understood. Using LC-MS/MS-based phosphoproteomics, we found that eukaryotic elongation factor 2 kinase (eEF2K), a key convergence point downstream of MAPK and PI3K pathways, mediates synergism to cotreatment with trametinib plus pictilisib (which target MEK1/2 and PI3Kα/δ, respectively). Inhibition of eEF2K by siRNA or with a small molecule inhibitor reversed the antiproliferative effects of the cotreatment with PI3K plus MEK inhibitors in a cell model-specific manner. Systematic analysis in 12 acute myeloid leukemia cell lines revealed that eEF2K activity was increased in cells for which PI3K plus MEKi cotreatment is synergistic, while PKC potentially mediated resistance to such cotreatment. Together, our study uncovers eEF2K activity as a key mediator of responses to PI3Ki plus MEKi and as a potential biomarker to predict synergy to cotreatment in cancer cells.

Lectin-like Transcript-1 (LLT1) Expression in Oral Squamous Cell Carcinomas: Prognostic Significance and Relationship with the Tumor Immune Microenvironment.

Lectin-like transcript-1 (LLT1) expression is detected in different cancer types and is involved in immune evasion. The present study investigates the clinical relevance of tumoral and stromal LLT1 expression in oral squamous cell carcinoma (OSCC), and relationships with the immune infiltrate into the tumor immune microenvironment (TIME). Immunohistochemical analysis of LLT1 expression was performed in 124 OSCC specimens, together with PD-L1 expression and the infiltration of CD20+, CD4+, and CD8+ lymphocytes and CD68+ and CD163+-macrophages. Associations with clinicopathological variables, prognosis, and immune cell densities were further assessed. A total of 41 (33%) OSCC samples showed positive LLT1 staining in tumor cells and 55 (44%) positive LLT1 in tumor-infiltrating lymphocytes (TILs). Patients harboring tumor-intrinsic LLT1 expression exhibited poorer survival, suggesting an immunosuppressive role. Conversely, positive LLT1 expression in TILs was significantly associated with better disease-specific survival, and also an immune-active tumor microenvironment highly infiltrated by CD8+ T cells and M1/M2 macrophages. Furthermore, the combination of tumoral and stromal LLT1 was found to distinguish three prognostic categories (favorable, intermediate, and adverse; p = 0.029, Log-rank test). Together, these data demonstrate the prognostic relevance of tumoral and stromal LLT1 expression in OSCC, and its potential application to improve prognosis prediction and patient stratification.

Combined PIK3CA and SOX2 Gene Amplification Predicts Laryngeal Cancer Risk beyond Histopathological Grading.

The PIK3CA and SOX2 genes map at 3q26, a chromosomal region frequently amplified in head and neck cancers, which is associated with poor prognosis. This study explores the clinical significance of PIK3CA and SOX2 gene amplification in early tumorigenesis. Gene copy number was analyzed by real-time PCR in 62 laryngeal precancerous lesions and correlated with histopathological grading and laryngeal cancer risk. Amplification of the SOX2 and PIK3CA genes was frequently detected in 19 (31%) and 32 (52%) laryngeal dysplasias, respectively, and co-amplification in 18 (29%) cases. The PIK3CA and SOX2 amplifications were predominant in high-grade dysplasias and significantly associated with laryngeal cancer risk beyond histological criteria. Multivariable Cox analysis further revealed PIK3CA gene amplification as an independent predictor of laryngeal cancer development. Interestingly, combined PIK3CA and SOX2 amplification allowed us to distinguish three cancer risk subgroups, and PIK3CA and SOX2 co-amplification was found the strongest predictor by ROC analysis. Our data demonstrate the clinical relevance of PIK3CA and SOX2 amplification in early laryngeal tumorigenesis. Remarkably, PIK3CA amplification was found to be an independent cancer predictor. Furthermore, combined PIK3CA and SOX2 amplification is emerging as a valuable and easy-to-implement tool for cancer risk assessment in patients with laryngeal precancerous lesions beyond current WHO histological grading.

Emerging Role of Decoy Receptor-2 as a Cancer Risk Predictor in Oral Potentially Malignant Disorders.

The aim of this study was to evaluate the expression of the senescence markers, Decoy Receptor 2 (DcR2) and Differentiated Embryo-Chondrocyte expressed gen 1 (DEC1), in oral potentially malignant disorders (OPMDs) to ascertain their possible association with oral cancer risk. The immunohistochemical analysis of DcR2 and DEC1 expression (along with p16 and Ki67 expression) was carried out in 60 patients with clinically diagnosed oral leukoplakia. Fifteen cases (25%) subsequently developed an invasive carcinoma. Correlations between protein marker expression, histological grade and oral cancer risk were assessed. DcR2, DEC1 and Ki67 protein expressions were found to correlate significantly with increased oral cancer risk, and also with an increased grade of dysplasia. Multivariate analysis demonstrated that DcR2 and Ki67 expression are independent predictors of oral cancer development. Our results evidence for the first time the potential of DcR2 as an early biomarker to assess oral cancer risk in patients with oral leukoplakia (HR = 59.7, p = 0.015), showing a superior predictive value to histology (HR = 4.225, p = 0.08). These findings reveal that the increased expression of DcR2 and DEC1 occurred frequently in OPMDs. In addition, DcR2 expression emerges as a powerful biomarker for oral cancer risk assessment in patients with oral leukoplakia.

Prevalence of human papillomavirus in oral squamous cell carcinomas in northern Spain.

The aim of this study was to analyze the prevalence of high-risk HPV in oral squamous cell carcinoma (OSCC) in a northern Spanish population, as well as to ascertain the prognostic role of p16INK4a expression. The examination samples were collected from paraffin tissue blocks, from 125 patients surgically treated between 1996 and 2007. All cases were histologically evaluated, and the presence of HPV was assessed by p16 and p53immunohistochemistry followed by DNA detection by in situ hybridization (ISH) and polymerase chain reaction (PCR) amplification using the combination of consensus primers MY11/GP6 + . Fourteen cases (11 %) were p16-immunopositive, and p53 was scored positive in 73 cases (58 %). Five cases (4 %) showed a simultaneous p16-positive and p53-negative immunostaining. ISH was negative in all the cases. Among the p16INK4a-immunopositive cases, PCR amplification failed to reveal HPV DNA in any tumor samples. There were no statistically significant differences in any clinical or pathological characteristics of the patients regarding p16INK4a expression. T classification, neck-node metastasis, and clinical stage showed outcome relevance. However, no significant differences in cause-specific survival based on p16INK4a were observed. We did not find any high-risk HPV types in our patients, thus, are unlikely that HPV has an important role in the etiology of OSCC. p16INK4a protein was neither an accurate marker of HPV infection nor a prognosis marker in OSCC.

Dissecting the functions of cancer-associated fibroblasts to therapeutically target head and neck cancer microenvironment.

Head and neck cancers (HNC) are a diverse group of aggressive malignancies with high morbidity and mortality, leading to almost half-million deaths annually worldwide. A better understanding of the molecular processes governing tumor formation and progression is crucial to improve current diagnostic and prognostic tools as well as to develop more personalized treatment strategies. Tumors are highly complex and heterogeneous structures in which growth and dissemination is not only governed by the cancer cells intrinsic mechanisms, but also by the surrounding tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) emerge as predominant TME components and key players in the generation of permissive conditions that ultimately impact in tumor progression and metastatic dissemination. Although CAFs were initially considered a consequence of tumor development, it is now well established that they actively contribute to numerous cancer hallmarks i.e., tumor cell growth, migration and invasion, cancer cell stemness, angiogenesis, metabolic reprograming, inflammation, and immune system modulation. In this scenario, therapeutic strategies targeting CAF functions could potentially have a major impact in cancer therapeutics, providing avenues for new treatment options or for improving efficacy in established approaches. This review is focused on thoroughly dissecting existing evidences supporting the contribution of CAFs in HNC biology with an emphasis on current knowledge of the key molecules and pathways involved in CAF-tumor crosstalk, and their potential as novel biomarkers and/or therapeutic targets to effectively interfere the tumor-stroma crosstalk for HNC patients benefit. involved in CAF-tumor crosstalk, and their potential as novel biomarkers and/or therapeutic targets to effec- tively interfere the tumor-stroma crosstalk for HNC patients benefit.

Driving role of head and neck cancer cell secretome on the invasion of stromal fibroblasts: Mechanistic insights by phosphoproteomics.

BACKGROUND: Cancer-associated fibroblasts (CAFs) are major players in tumor-stroma communication, and participate in several cancer hallmarks to drive tumor progression and metastatic dissemination. This study investigates the driving effects of tumor-secreted factors on CAF biology, with the ultimate goal of identifying effective therapeutic targets/strategies for head and neck squamous cell carcinomas (HNSCC). METHODS: Functionally, conditioned media (CM) from different HNSCC-derived cell lines and normal keratinocytes (Kc) were tested on the growth and invasion of populations of primary CAFs and normal fibroblasts (NFs) using 3D invasion assays in collagen matrices. The changes in MMPs expression were evaluated by RT-qPCR and kinase enrichment was analyzed using mass spectrometry phosphoproteomics. RESULTS: Our results consistently demonstrate that HNSCC-secreted factors (but not Kc CM) specifically and robustly promoted pro-invasive properties in both CAFs and NFs, thereby reflecting the plasticity of fibroblast subtypes. Concomitantly, HNSCC-secreted factors massively increased metalloproteinases levels in CAFs and NFs. By contrast, HNSCC CM and Kc CM exhibited comparable growth-promoting effects on stromal fibroblasts. Mechanistically, phosphoproteomic analysis predominantly revealed phosphorylation changes in fibroblasts upon treatment with HNSCC CM, and various promising kinases were identified: MKK7, MKK4, ASK1, RAF1, BRAF, ARAF, COT, PDK1, RSK2 and AKT1. Interestingly, pharmacologic inhibition of RAF1/BRAF using sorafenib emerged as the most effective drug to block tumor-promoted fibroblast invasion without affecting fibroblast viability CONCLUSIONS: Our findings demonstrate that HNSCC-secreted factors specifically fine tune the invasive potential of stromal fibroblasts, thereby generating tumor-driven pro-invasive niches, which in turn to ultimately facilitate cancer cell dissemination. Furthermore, the RAF/BRAF inhibitor sorafenib was identified as a promising candidate to effectively target the onset of pro-invasive clusters of stromal fibroblasts in the HNSCC microenvironment.

Targeting oncogenic functions of miR-301a in head and neck squamous cell carcinoma by PI3K/PTEN and MEK/ERK pathways.

Treatment of head and neck squamous cell carcinomas (HNSCC), the sixth most frequent cancer worldwide, remains challenging. miRNA dysregulation is closely linked to tumorigenesis and tumor progression, thus emerging as suitable targets for cancer treatment. Transcriptomic analysis of TCGA HNSCC dataset revealed that miR-301a expression levels significantly increased in primary tumors, as compared to patient-matched normal tissue. This prompted us to investigate its pathobiological role and potential as new therapeutic target using different preclinical HNSCC models. miR-301a overexpression in HNSCC-derived cell lines led to enhanced proliferation and invasion, whereas miR-301 inhibition reduced these effects. In vivo validation was performed using an orthotopic mouse model. Results concordantly showed that the mitotic counts, the percentage of infiltration depth and Ki67 proliferative index were significantly augmented in the subgroup of mice harboring miR-301a-overexpressing tumors. Further mechanistic characterization revealed PI3K/PTEN/AKT and MEK/ERK pathways as central signaling nodes responsible for mediating the oncogenic activity of miR-301a observed in HNSCC cells. Notably, pharmacological disruption of PI3K and ERK signals with BYL-719 and PD98059, respectively, was effective to completely revert/abolish miR-301a-promoted tumor cell growth and invasion. Altogether, these findings demonstrate that miR-301a dysregulation plays an oncogenic role in HNSCC, thus emerging as a candidate therapeutic target for this disease. Importantly, available PI3K and ERK inhibitors emerge as promising anti-tumor agents to effectively target miR-301a-mediated signal circuit hampering growth-promoting and pro-invasive functions.

Role of HERG1 potassium channel in both malignant transformation and disease progression in head and neck carcinomas.

Evidence indicates that human ether à-go-go-related gene 1 (HERG1) voltage-gated potassium channels could represent new valuable membrane therapeutic targets and diagnostic/prognostic biomarkers in various cancers. This study is the first to investigate the expression pattern of HERG1 potassium channel subunit in both primary tumors and precancerous lesions to establish its clinical and biological role during the development and progression of head and neck squamous cell carcinomas. HERG1 protein expression was evaluated by immunohistochemistry in paraffin-embedded tissue specimens from 133 patients with laryngeal/hypopharyngeal squamous cell carcinomas and 75 patients with laryngeal dysplasia, and correlated with clinical data. Our findings demonstrate that HERG1 is frequently aberrantly expressed in a high percentage of primary tumors (87%), whereas expression was negligible in both stromal cells and normal-adjacent epithelia. HERG1 expression increased during head and neck squamous cell carcinoma progression and was significantly associated with lymph node metastasis (P=0.04), advanced disease stages (P<0.001), regional tumor recurrence (P=0.004), distant metastasis (P=0.03) and reduced disease-specific survival (P=0.012, log-rank test). HERG1-positive expression was also detected in 31 (41%) of 75 laryngeal dysplasias. Interestingly, HERG1 expression increased with the grade of dysplasia; however, HERG1 expression but not histology correlated significantly with increased laryngeal cancer risk (P=0.007). In addition, functional studies in head and neck squamous cell carcinoma-derived cell lines further revealed that HERG1 expression promotes anchorage-dependent and -independent cell growth and invasive capability, although independently of its ion-conducting function. Our data demonstrate that HERG1 expression is a biologically and clinically relevant feature in head and neck squamous cell carcinoma progression and also during malignant transformation, and a promising candidate as cancer risk marker and therapeutic target for head and neck squamous cell carcinoma prevention and treatment.

Pathobiological functions and clinical implications of annexin dysregulation in human cancers.

Annexins are an extensive superfamily of structurally related calcium- and phospholipid-binding proteins, largely conserved and widely distributed among species. Twelve human annexins have been identified, referred to as Annexin A1-13 (A12 remains as of yet unassigned), whose genes are spread throughout the genome on eight different chromosomes. According to their distinct tissue distribution and subcellular localization, annexins have been functionally implicated in a variety of biological processes relevant to both physiological and pathological conditions. Dysregulation of annexin expression patterns and functions has been revealed as a common feature in multiple cancers, thereby emerging as potential biomarkers and molecular targets for clinical application. Nevertheless, translation of this knowledge to the clinic requires in-depth functional and mechanistic characterization of dysregulated annexins for each individual cancer type, since each protein exhibits varying expression levels and phenotypic specificity depending on the tumor types. This review specifically and thoroughly examines the current knowledge on annexin dysfunctions in carcinogenesis. Hence, available data on expression levels, mechanism of action and pathophysiological effects of Annexin A1-13 among different cancers will be dissected, also further discussing future perspectives for potential applications as biomarkers for early diagnosis, prognosis and molecular-targeted therapies. Special attention is devoted to head and neck cancers (HNC), a complex and heterogeneous group of aggressive malignancies, often lately diagnosed, with high mortality, and scarce therapeutic options.

An intrinsic temporal order of c-JUN N-terminal phosphorylation regulates its activity by orchestrating co-factor recruitment.

Protein phosphorylation is a major regulatory mechanism of cellular signalling. The c-JUN proto-oncoprotein is phosphorylated at four residues within its transactivation domain (TAD) by the JNK family kinases, but the functional significance of c-JUN multisite phosphorylation has remained elusive. Here we show that c-JUN phosphorylation by JNK exhibits defined temporal kinetics, with serine63 and serine73 being phosphorylated more rapidly than threonine91 and threonine93. We identify the positioning of the phosphorylation sites relative to the kinase docking motif, and their primary sequence, as the main factors controlling phosphorylation kinetics. Functional analysis reveals three c-JUN phosphorylation states: unphosphorylated c-JUN recruits the MBD3 repressor, serine63/73 doubly-phosphorylated c-JUN binds to the TCF4 co-activator, whereas the fully phosphorylated form disfavours TCF4 binding attenuating JNK signalling. Thus, c-JUN phosphorylation encodes multiple functional states that drive a complex signalling response from a single JNK input.

Frequent Alteration of Annexin A9 and A10 in HPV-Negative Head and Neck Squamous Cell Carcinomas: Correlation with the Histopathological Differentiation Grade.

The annexin protein superfamily has been implicated in multiple physiological and pathological processes, including carcinogenesis. Altered expression of various annexins has frequently been observed and linked to the development and progression of various human malignancies. However, information is lacking on the expression and clinical significance of annexin A9 (ANXA9) and A10 (ANXA10) in head and neck squamous cell carcinomas (HNSCC). ANXA9 and ANXA10 expression was evaluated in a large cohort of 372 surgically treated HPV-negative HNSCC patients and correlated with the clinicopathologic parameters and disease outcomes. Down-regulation of ANXA9 expression was found in 42% of HNSCC tissue samples, compared to normal epithelia. ANXA9 expression in tumors was significantly associated with oropharyngeal location and histological differentiation grade (P < 0.001). In marked contrast, ANXA10 expression was absent in normal epithelium, but variably detected in the cytoplasm of cancer cells. Positive ANXA10 expression was found in 64% of tumors, and was significantly associated with differentiation grade (P < 0.001), being also more frequent in oropharyngeal tumors (P = 0.019). These results reveal that the expression of both ANXA9 and ANXA10 is frequently altered in HNSCC and associated to the tumor differentiation grade, suggesting that they could be implicated in the pathogenesis of these cancers.

Immunohistochemical Expression of Cortactin and Focal Adhesion Kinase Predicts Recurrence Risk and Laryngeal Cancer Risk Beyond Histologic Grading.

Background: Cortactin (CTTN) and the focal adhesion kinase (FAK) are two major candidate genes to, respectively, drive 11q13- and 8q24-associated aggressive behavior in various cancers. Recent evidence uncovered their clinical relevance in early stages of tumorigenesis as promising biomarkers for cancer risk assessment.Methods: Using a multicenter validation study, CTTN and FAK expression was evaluated by immunohistochemistry (IHC) in a cohort of 109 patients with laryngeal precancerous lesions, and correlated with clinicopathologic parameters and laryngeal cancer risk. The pathophysiologic role of CTTN and FAK was further investigated using functional studies in cellular models.Results: Positive CTTN and FAK expression (scores 2 and 3) was detected in 49 (41%) and 35 (32%) laryngeal dysplasias, respectively. Univariate Cox analysis showed that CTTN and FAK expression but not histologic grading was significantly associated with both recurrence risk and laryngeal cancer risk. Patients carrying strong CTTN- or FAK-expressing lesions (score 3) experienced the highest laryngeal cancer incidence (log-rank P < 0.001). In multivariate stepwise analysis, FAK expression [HR = 13.91; 95% CI, 4.82-40.15; P < 0.001] and alcohol consumption (HR = 2.22; 95% confidence interval, 1.17-4.20; P = 0.014) were significant independent predictors of laryngeal cancer development. Targeting FAK by either RNAi or pharmacologic inhibitors effectively blocked cell growth, colony formation, and invasion into 3D collagen matrices.Conclusions: CTTN and FAK emerge as powerful predictors of laryngeal cancer risk and recurrence risk beyond histologic grading.Impact: Our work supports the applicability of IHC CTTN and FAK as complementary markers for risk stratification in patients with laryngeal precancerous lesions. Cancer Epidemiol Biomarkers Prev; 27(7); 805-13. ©2018 AACR.

Factors Secreted by Cancer-Associated Fibroblasts that Sustain Cancer Stem Properties in Head and Neck Squamous Carcinoma Cells as Potential Therapeutic Targets.

This study investigates for the first time the crosstalk between stromal fibroblasts and cancer stem cell (CSC) biology in head and neck squamous cell carcinomas (HNSCC), with the ultimate goal of identifying effective therapeutic targets. The effects of conditioned media from cancer-associated fibroblasts (CAFs) and normal fibroblasts (NFs) on the CSC phenotype were assessed by combining functional and expression analyses in HNSCC-derived cell lines. Further characterization of CAFs and NFs secretomes by mass spectrometry was followed by pharmacologic target inhibition. We demonstrate that factors secreted by CAFs but not NFs, in the absence of serum/supplements, robustly increased anchorage-independent growth, tumorsphere formation, and CSC-marker expression. Modulators of epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGFR), and platelet-derived growth factor receptor (PDGFR) activity were identified as paracrine cytokines/factors differentially secreted between CAFs and NFs, in a mass spectrometry analysis. Furthermore, pharmacologic inhibition of EGFR, IGFR, and PDGFR significantly reduced CAF-induced tumorsphere formation and anchorage-independent growth suggesting a role of these receptor tyrosine kinases in sustaining the CSC phenotype. These findings provide novel insights into tumor stroma⁻CSC communication, and potential therapeutic targets to effectively block the CAF-enhanced CSC niche signaling circuit.

Distinctive Expression and Amplification of Genes at 11q13 in Relation to HPV Status with Impact on Survival in Head and Neck Cancer Patients.

Clear differences have been established between head and neck squamous cell carcinomas (HNSCC) depending on human papillomavirus (HPV) infection status. This study specifically investigated the status of the CTTN, CCND1 and ANO1 genes mapping at the 11q13 amplicon in relation to the HPV status in HNSCC patients. CTTN, CCND1 and ANO1 protein expression and gene amplification were respectively analyzed by immunohistochemistry and real-time PCR in a homogeneous cohort of 392 surgically treated HNSCC patients. The results were further confirmed using an independent cohort of 279 HNSCC patients from The Cancer Genome Atlas (TCGA). The impact on patient survival was also evaluated. CTTN, CCND1 and ANO1 gene amplification and protein expression were frequent in HPV-negative tumors, while absent or rare in HPV-positive tumors. Using an independent validation cohort of 279 HNSCC patients, we consistently found that these three genes were frequently co-amplified (28%) and overexpressed (39⁻46%) in HPV-negative tumors, whereas almost absent in HPV-positive tumors. Remarkably, these alterations (in particular CTTN and ANO1 overexpression) were associated with poor prognosis. Taken together, the distinctive expression and amplification of these genes could cooperatively contribute to the differences in prognosis and clinical outcome between HPV-positive and HPV-negative tumors. These findings could serve as the basis to design more personalized therapeutic strategies for HNSCC patients.

Annexin A1 down-regulation in head and neck squamous cell carcinoma is mediated via transcriptional control with direct involvement of miR-196a/b.

Annexin A1 (ANXA1) down-regulation is an early and frequent event in the development of head and neck squamous cell carcinomas (HNSCC). In an attempt to identify the underlying mechanisms of reduced ANXA1 protein expression, this study investigated ANXA1 mRNA expression in HNSCC specimens by both in situ hybridization and RT-qPCR. Results showed a perfect concordance between the pattern of ANXA1 mRNA and protein detected by immunofluorescence in tumors, precancerous lesions and normal epithelia, reflecting that ANXA1 down-regulation occurs at transcriptional level. We also found that both miR-196a and miR-196b levels inversely correlated with ANXA1 mRNA levels in paired HNSCC tissue samples and patient-matched normal mucosa. In addition, endogenous levels of ANXA1 mRNA and protein were consistently and significantly down-regulated upon miR-196a and miR-196b over-expression in various HNSCC-derived cell lines. The direct interaction of both mature miR-196a and miR-196b was further confirmed by transfection with Anxa1 3'UTR constructs. Combined bioinformatics and functional analysis of ANXA1 promoter activity contributed to identify key regions and potential mediators of ANXA1 transcriptional control. This study unveils that, in addition to miR-196a, miR-196b also directly targets ANXA1 in HNSCC.

Dysregulation of Mir-196b in Head and Neck Cancers Leads to Pleiotropic Effects in the Tumor Cells and Surrounding Stromal Fibroblasts.

The miR-196 family members have been found dysregulated in different cancers. Therefore, they have been proposed as promising biomarkers and therapeutic targets. This study is the first to investigate the role of miR-196b in the development and progression of head and neck squamous cell carcinomas (HNSCC), and also the impact on the surrounding tumor microenvironment. Increased miR-196b levels were detected in 95% of primary tumors and precancerous lesions, although no significant differences were observed between non-progressing versus progressing dysplasias. Furthermore, increased levels of both miR-196a and miR-196b were successfully detected in saliva samples from HNSCC patients. The functional consequences of altered miR-196 expression were investigated in both HNSCC cell lines and cancer-associated fibroblasts (CAFs) by transfection with specific pre-miR precursors. Results showed that both miR-196a and miR-196b elicit cell-specific responses in target genes and downstream regulatory pathways, and have a distinctive impact on cell proliferation, migration and invasion. These data reveal the early occurrence and prevalence of miR-196b dysregulation in HNSCC tumorigenesis, suggesting its utility for early diagnosis and/or disease surveillance and also as a non-invasive biomarker in saliva. The pleiotropic effects of miR-196a/b in HNSCC cell subpopulations and surrounding CAFs may complicate a possible therapeutic application.

Cleavage of Fibulin-2 by the aggrecanases ADAMTS-4 and ADAMTS-5 contributes to the tumorigenic potential of breast cancer cells.

Fibulin-2 participates in the assembly of extracellular matrix components through interactions with multiple ligands and promotes contacts between cells and their surrounding environment. Consequently, identification of processes that could lead to an altered Fibulin-2 could have a major impact not only in the maintenance of tissue architecture and morphogenesis but also in pathological situations including cancer. Herein, we have investigated the ability of the secreted metalloproteases ADAMTS-4 and ADAMTS-5 to digest Fibulin-2. Using in vitro approaches and cultured breast cancer cell lines we demonstrate that Fibulin-2 is a better substrate for ADAMTS-5 than it is for ADAMTS-4. Moreover, Fibulin-2 degradation is associated to an enhancement of the invasive potential of T47D, MCF-7 and SK-BR-3 cells. We have also found that conditioned medium from MCF-7 cells that simultaneously overexpress Fibulin-2 and ADAMTS-5 significantly induced the migratory and invasive ability of normal breast fibroblasts using 3D collagen matrices. Immunohistochemical analysis highlights the close proximity or partial overlap of both Fibulin-2 and ADAMTS-5 in breast tumor samples. Additionally, proteolytic products derived from a potential degradation of Fibulin-2 by ADAMTS-5 were also identified in these samples. Finally, we also show that the cleavage of Fibulin-2 by ADAMTS-5 is counteracted by ADAMTS-12, a metalloprotease that interacts with Fibulin-2. Overall, our results provide direct evidence indicating that Fibulin-2 is a novel substrate of ADAMTS-5 and that this proteolysis could alter the cellular microenvironment affecting the balance between protumor and antitumor effects associated to both Fibulin-2 and the ADAMTSs metalloproteases.

HERG1A potassium channel is the predominant isoform in head and neck squamous cell carcinomas: evidence for regulation by epigenetic mechanisms.

Evidences indicate that HERG1 voltage-gated potassium channel is frequently aberrantly expressed in various cancers including head and neck squamous cell carcinomas (HNSCC), representing a clinically and biologically relevant feature during disease progression and a potential therapeutic target. The present study further and significantly extends these data investigating for the first time the expression and individual contribution of HERG1 isoforms, their clinical significance during disease progression and also the underlying regulatory mechanisms. Analysis of HERG1A and HERG1B expression using real-time RT-PCR consistently showed that HERG1A is the predominant isoform in ten HNSCC-derived cell lines tested. HERG2 and HERG3 were also detected. Immunohistochemical analysis of HERG1A expression on 133 HNSCC specimens demonstrated that HERG1A expression increased during tumour progression and correlated significantly with reduced disease-specific survival. Furthermore, our study provides original evidence supporting the involvement of histone acetylation (i.e. H3Ac and H4K16Ac activating marks) in the regulation of HERG1 expression in HNSCC. Interestingly, this mechanism was also found to regulate the expression of another oncogenic channel (Kv3.4) as well as HERG2 and HERG3. These data demonstrate that HERG1A is the predominant and disease-relevant isoform in HNSCC progression, while histone acetylation emerges as an important regulatory mechanism underlying Kv gene expression.