MEK Is a Potential Indirect Target in Subtypes of Head and Neck Cancers.

The poor prognosis of head-and-neck squamous cell carcinoma (HNSCC) is partly due to the lack of reliable prognostic and predictive markers. The Ras/Raf/MEK/ERK signaling pathway is often activated by overexpressed epidermal growth factor receptor (EGFR) and stimulates the progression of HNSCCs. Our research was performed on three human papillomavirus (HPV)-negative HNSCC-cell lines: Detroit 562, FaDu and SCC25. Changes in cell viability upon EGFR and/or MEK inhibitors were measured by the MTT method. The protein-expression and phosphorylation profiles of the EGFR-initiated signaling pathways were assessed using Western-blot analysis. The EGFR expression and pY1068-EGFR levels were also studied in the patient-derived HNSCC samples. We found significant differences between the sensitivity of the tumor-cell lines used. The SCC25 line was found to be the most sensitive to the MEK inhibitors, possibly due to the lack of feedback Akt activation through EGFR. By contrast, this feedback activation had an important role in the FaDu cells. The observed insensitivity of the Detroit 562 cells to the MEK inhibitors might have been caused by their PIK3CA mutation. Among HNSCC cell lines, EGFR-initiated signaling pathways are particularly versatile. An ERK/EGFR feedback loop can lead to Akt-pathway activation upon MEK inhibition, and it is related not only to increased amounts of EGFR but also to the elevation of pY1068-EGFR levels. The presence of this mechanism may justify the combined application of EGFR and MEK inhibitors.

The Potential Impact of Connexin 43 Expression on Bcl-2 Protein Level and Taxane Sensitivity in Head and Neck Cancers-In Vitro Studies.

The poor prognosis of head and neck squamous cell carcinoma (HNSCC) is partly due to the lack of reliable predictive markers. Connexin 43 (Cx43) protein and its cell-communication channels have been assigned tumor suppressor functions while the anti-apoptotic Bcl-2 (B-cell lymphoma-2) protein has been associated with negative prognostic significance in cancer. This study aimed to test the role of Cx43 protein on Bcl-2 expression, tumor progression and response to taxane-based treatment in HNSCC. Human papillomavirus (HPV) negative HNSCC cell lines were tested for paclitaxel sensitivity through measuring apoptosis induction, cell viability and changes in Cx43 and Bcl-2 levels using flow cytometry, cell viability assay, immunocytochemistry and western blot. Inhibition of Cx43 expression using siRNA increased Bcl-2 protein levels in SCC25 (tongue squamous cell carcinoma) cells, while forced Cx43 expression reduced Bcl-2 levels and supported paclitaxel cytotoxicity in FaDu (hypopharynx squamous cell carcinoma) cells. In vitro results were in line with protein expression and clinicopathological features tested in tissue microarray samples of HNSCC patients. Our data demonstrate that elevated Cx43 and reduced Bcl-2 levels may indicate HNSCC sensitivity to taxane-based treatments. On the contrary, silencing of the Cx43 gene GJA1 (gap junction protein alpha-1) can result in increased Bcl-2 expression and reduced paclitaxel efficiency. Clinical tumor-based analysis also confirmed the inverse correlation between Cx43 and Bcl-2 expression.

Suitability of GnRH Receptors for Targeted Photodynamic Therapy in Head and Neck Cancers.

Head and neck squamous cell carcinomas (HNSCC) have a high mortality rate, although several potential therapeutic targets have already been identified. Gonadotropin-releasing hormone receptor (GnRH-R) expression is less studied in head and neck cancers, hence, we investigated the therapeutic relevance of GnRH-R targeting in HNSCC patients. Our results indicate that half of the patient-derived samples showed high GnRH-R expression, which was associated with worse prognosis, making this receptor a promising target for GnRH-based drug delivery. Photodynamic therapy is a clinically approved treatment for HNSCC, and the efficacy and selectivity may be enhanced by the covalent conjugation of the photosensitizer to a GnRH-R targeting peptide. Several native ligands, gonadotropin-releasing hormone (GnRH) isoforms, are known to target GnRH-R effectively. Therefore, different 4Lys(Bu) modified GnRH analogs were designed and conjugated to protoporphyrin IX. The receptor binding potency of the novel conjugates was measured on human pituitary and human prostate cancer cells, indicating only slightly lower GnRH-R affinity than the peptides. The in vitro cell viability inhibition was tested on Detroit-562 human pharyngeal carcinoma cells that express GnRH-R in high levels, and the results showed that all conjugates were more effective than the free protoporphyrin IX.

Discovery and optimization of novel benzothiophene-3-carboxamides as highly potent inhibitors of Aurora kinases A and B.

Aurora kinases as regulators of cell division have become promising therapeutic targets recently. Here we report novel, low molecular weight benzothiophene-3-carboxamide derivatives designed and optimized for inhibiting Aurora kinases. The most effective compound 36 inhibits Aurora kinases in vitro in the nanomolar range and diminishes HCT 116 cell viability blocking cytokinesis and inducing apoptosis. According to western blot analysis, the lead molecule inhibits Aurora kinases equipotently to VX-680 (Tozasertib) and similarly synergizes with other targeted drugs.

Expression of PD-L1 on Immune Cells Shows Better Prognosis in Laryngeal, Oropharygeal, and Hypopharyngeal Cancer.

Despite great enthusiasm towards immunotherapy, reliable biomarkers are still lacking. The importance of subsets based on human papillomavirus (HPV) status is supported by a growing body of evidence. However, role of other possible subgroups such as anatomic localization of primary tumor remains controversial. Our objective was to investigate immune cell infiltrate and checkpoint inhibitor proteins in above-mentioned head and neck cancer subsets. Archival tumor samples of 106 laryngeal, oropharyngeal, and hypopharyngeal cancer patients were stained with PD-L1, PD-L2, PD-1, and CTLA-4 antibodies. Proportion of tumor-infiltrating lymphocytes was assessed as well. In HPV-negative tumors, PD-L1 immune cell positivity was associated with better disease-specific survival. PD-L1 expression on immune cells correlated with improved disease-specific survival in laryngeal tumors. Furthermore, PD-L1 immune cell positivity correlated with CTLA-4 expression on immune cells and it was accompanied by high tumor-infiltrating lymphocyte rate. PD-L1 expression on tumor cells and PD-1 status showed strong correlation in all patients and in oropharyngeal and laryngeal localization, but not in hypopharynx. HPV-negative oropharyngeal cancers showed negative PD-L1 status on tumor cells. CTLA-4 positivity was observed in 49.5% and 20.6% on immune cells and on tumor cells, respectively. We concluded that PD-L1 expression on immune cells indicates better prognosis in laryngeal squamous cell carcinoma and in HPV-negative head and neck squamous cell carcinoma. We have not found any essential differences between anatomic subgroups. A possibly distinct role of hypopharyngeal localization regarding immune activity requires further clarification.

Molecular subtype specific efficacy of MEK inhibitors in pancreatic cancers.

Pancreatic cancer is an increasing cause of cancer related death worldwide. KRAS is the dominant oncogene in this cancer type and molecular rationale would indicate, that inhibitors of the downstream target MEK could be appropriate targeted agents, but clinical trials have failed so far to achieve statistically significant benefit in unselected patients. We aimed to identify predictive molecular biomarkers that can help to define subgroups where MEK inhibitors might be beneficial alone or in combination. Next-generation sequencing data of 50 genes in three pancreatic cancer cell lines (MiaPaCa2, BxPC3 and Panc1) were analyzed and compared to the molecular profile of 138 clinical pancreatic cancer samples to identify the molecular subtypes of pancreatic cancer these cell lines represent. Luminescent cell viability assay was used to determine the sensitivity of cell lines to kinase inhibitors. Western blot was used to analyze the pathway activity of the examined cell lines. According to our cell viability and pathway activity data on these model cell lines only cells harboring the rare G12C KRAS mutation and low EGFR expression are sensitive to single MEK inhibitor (trametinib) treatment. The common G12D KRAS mutation leads to elevated baseline Akt activity, thus treatment with single MEK inhibitors fails. However, combination of MEK and Akt inhibitors are synergistic in this case. In case of wild-type KRAS and high EGFR expression MEK inhibitor induced Akt phosphorylation leads to trametinib resistance which necessitates for MEK and EGFR or Akt inhibitor combination treatment. In all we provide strong preclinical rational and possible molecular mechanism to revisit MEK inhibitor therapy in pancreatic cancer in both monotherapy and combination, based on molecular profile analysis of pancreatic cancer samples and cell lines. According to our most remarkable finding, a small subgroup of patients with G12C KRAS mutation may still benefit from MEK inhibitor monotherapy.

p16INK4 expression is of prognostic and predictive value in oropharyngeal cancers independent of human papillomavirus status: a Hungarian study.

Head and neck cancer treatment protocols still lack well-established biomarkers of prognostic and predictive value. It is well known that human papillomavirus (HPV)-related and non-HPV-related oropharyngeal cancers are distinct entities concerning tumor biology and clinical outcome. However, there is an ongoing debate whether tumor suppressor p16INK4 status alone or both p16INK4 and HPV detection should be used in clinical settings. The aim of this study was to investigate p16INK4-immunolabelled and HPV-induced rates and determine their clinical significance in 110 primary head and neck squamous cell carcinomas. The expression of p16INK4 protein was assessed with immunohistochemistry, while high-risk HPV detection was performed using DNA PCR method. P16INK4 immunolabelling was detected in 17.3% of all tumor samples, and in 38.1% of oropharyngeal malignancies. Oropharyngeal, p16INK4-immunolabelled tumors showed an improved disease-specific survival compared to the non-p16INK4-immunolabelled group (median survival: 30.3 vs. 8.8 months, p < 0.001 with the log-rank test). Furthermore, 56% of p16INK4-immunolabelled cases were tested positive for HPV-DNA. The HPV-induced group presented better disease-specific survival compared to the non-HPV-induced cases (median survival: 25.9 vs. 9.5 months, p = 0.024 with the log-rank test). Improved response rates to neoadjuvant chemotherapy were observed both in p16INK4-immunolabelled and p16INK4- immunolabelled/HPV DNA- containing groups (Fisher's exact test: p = 0.025 and p = 0.009). In conclusion, p16INK4 immunohistochemistry proved to be a reliable and affordable tool for prognostic and predictive testing of head and neck squamous cell cancers. The p16INK4 immunopositivity status alone was confirmed to be an equally precise indicator of clinical outcome as p16INK4/HPV DNA PCR double testing.

Copy number gain of PIK3CA and MET is associated with poor prognosis in head and neck squamous cell carcinoma.

The incidence of head and neck squamous cell carcinomas is still growing, and the long-term prognosis of advanced disease remains poor. Only a fraction of head and neck cancers are sensitive to the EGFR-inhibitor cetuximab, which is the only registered targeted therapy available today. In several cancers, gene copy number alterations of MET and PIK3CA have been found to be prognostic and predictive for therapy response. The aim of this study was to systematically analyze in head and neck cancers the pathological characteristics and prognostic significance of copy number changes of MET and PIK3CA genes. MET and PIK3CA copy numbers were analyzed by fluorescence in situ hybridization in tumor samples of 152 patients. Expression of EGFR, p16, and Ki67 was studied by immunohistochemistry. High polysomy of PIK3CA (chromosome 3) was found in 20 % of cases and amplification in 4.5 %. Regarding MET, 35 % of cases showed low or high polysomy of the gene (chromosome 7), while no intra-chromosomal amplification of MET was detected. PIK3CA copy number gain (high polysomy or amplification) was significantly associated with shorter disease-specific survival, larger tumor volume, and lower p16 expression. MET copy number gain (low or high polysomy) in tumors was significantly associated with shorter disease-specific survival and lower level of EGFR. PIK3CA and MET may play an important role in oncogenesis of certain specific subtypes of head and neck cancer. There is an urgent need for the development of novel targeted therapies against these tumors associated with poor prognosis.

The Potential Prognostic Value of Connexin 43 Expression in Head and Neck Squamous Cell Carcinomas.

Gap juctions are transmembrane communication channels known to be involved in the control of cell proliferation by mediating the exchange of ions and small molecules between cells. Gap junctions are composed of connexon hemichannels made up of 6 connexin proteins, which abnormal expression and functions have been linked to tumor progression and poorer prognosis. Here, we studied the prognostic impact of the most prevalent connexin isotype, connexin 43 (Cx43) in head and neck squamous cell carcinomas (HNSCC). Tissue microarrays made from tumor samples of 90 HNSCC patients were immunostained for Cx43 and cell cycle regulation-related biomarkers including p53, Ki67, p16, aurora A, geminin, and p21 proteins. Scoring and histopathologic evaluation were performed in digital slides. A 4-tier scoring distinguishing the percentage of positively stained tumor cells was used including score 1: <5%, score 2: 6% to 20%, score 3: 21% to 60%, and score 4: >60%. For statistics, Kaplan-Meier curves with log-rank tests, Cox-regression, and Pearson χ/Fisher exact tests were used.A significant positive correlation was found between Cx43 expression and disease-specific survival of patients (P=0.004). The rate of p21 protein-positive tumor cells also proved to be a significant positive prognostic marker (P=0.014). Cx43 levels also showed a significant positive correlation with p53 expression (P=0.036). However, there was no statistical association between Cx43 levels and the rest of the markers tested neither with T, N, or M stage.In conclusion, our data suggest that reduced Cx43 expression and low p21 protein levels may have a significant negative impact on HNSCC prognosis.

Targeting vascular endothelial growth factor receptor 2 and protein kinase D1 related pathways by a multiple kinase inhibitor in angiogenesis and inflammation related processes in vitro.

Emerging evidence suggests that the vascular endothelial growth factor receptor 2 (VEGFR2) and protein kinase D1 (PKD1) signaling axis plays a critical role in normal and pathological angiogenesis and inflammation related processes. Despite all efforts, the currently available therapeutic interventions are limited. Prior studies have also proved that a multiple target inhibitor can be more efficient compared to a single target one. Therefore, development of novel inflammatory pathway-specific inhibitors would be of great value. To test this possibility, we screened our molecular library using recombinant kinase assays and identified the previously described compound VCC251801 with strong inhibitory effect on both VEGFR2 and PKD1. We further analyzed the effect of VCC251801 in the endothelium-derived EA.hy926 cell line and in different inflammatory cell types. In EA.hy926 cells, VCC251801 potently inhibited the intracellular activation and signaling of VEGFR2 and PKD1 which inhibition eventually resulted in diminished cell proliferation. In this model, our compound was also an efficient inhibitor of in vitro angiogenesis by interfering with endothelial cell migration and tube formation processes. Our results from functional assays in inflammatory cellular models such as neutrophils and mast cells suggested an anti-inflammatory effect of VCC251801. The neutrophil study showed that VCC251801 specifically blocked the immobilized immune-complex and the adhesion dependent TNF-α -fibrinogen stimulated neutrophil activation. Furthermore, similar results were found in mast cell degranulation assay where VCC251801 caused significant reduction of mast cell response. In summary, we described a novel function of a multiple kinase inhibitor which strongly inhibits the VEGFR2-PKD1 signaling and might be a novel inhibitor of pathological inflammatory pathways.

Correlations between prognosis and regional biomarker profiles in head and neck squamous cell carcinomas.

Head and neck squamous cell carcinomas (HNSCC) show diverse clinicopathological features and are mostly linked with poor outcome. In this study, we tested if the expression of tumor growth, cell cycle and basement membrane anchorage related biomarkers allow prognostic and clinicopathological stratification of HNSCC. Archived HNSCC samples from 226 patients included into tissue microarrays (TMA) were tested using immunohistochemistry. Histopathological evaluation and the analysis of immunostaining for EGFR, Ki67, p53, p16(ink4) and Collagen XVII proteins were carried out in digital whole slides. Statistical evaluation was carried out using Pearson's Chi-square test and Kaplan-Meier survival analysis. In the tested cohort, hypopharyngeal cancers had the least favorable, and glottic cancers had the most favorable prognosis. High Ki67 positive tumor cell fractions were associated with significantly worse prognosis and elevated rate of lymph node metastasis. Both Ki67 and EGFR expression correlated significantly with the tumor localization. Ki67 index was the highest in the hypopharyngeal region and it proved to be the lowest in the glottic region. EGFR expression was the highest in the oral cavity and the lowest in the glottic region. The survival rate of patients with p16(ink4)-negative cancer was significantly lower than of those with p16(ink4)-positive disease. A significant inverse correlation was found between histological grade and the prognosis of HNSCC. Our data support that elevated Ki67 positive proliferating cell fractions contribute to the unfavorable prognosis of hypopharyngeal cancers, while glottic cancers have the most favorable prognosis because of the lowest Ki67 expression rate.

Major partial response to crizotinib, a dual MET/ALK inhibitor, in a squamous cell lung (SCC) carcinoma patient with de novo c-MET amplification in the absence of ALK rearrangement.

The initial radiotherapy of a 73 years old Caucasian male patient with advanced squamous cell lung carcinoma was terminated due to severe pericarditis. Subsequently, the tumor sample was analyzed for possible targets with comprehensive molecular diagnostics. EGFR, KRAS and PIK3CA genes were wild type, ALK and ROS1 were negative for rearrangement, but c-MET was amplified by fluorescent in situ hybridization. The kinase inhibitor crizotinib is already in clinical use for the treatment of ALK positive non-small cell lung cancers, but it is also known to be a potent c-MET inhibitor. The patient was treated with the standard dose of twice a day 250 mg crizotinib as a monotherapy. Major partial response to therapy was confirmed by chest CT and PET/CT after 8 weeks on therapy. C-MET expression is associated with poor prognosis and resistance to EGFR inhibitors. This case may indicate that c-MET tyrosine kinase inhibitors can be an effective targeted treatment option for squamous cell carcinoma patients, and future clinical trials should be expanded for this patient group as well.

Differential biomarker expression in head and neck cancer correlates with anatomical localization.

We tested the expression of known (p16(ink4), Ki67, p53, EGFR) and a new immunohistochemical (collagen XVII/BP180) biomarker in head and neck squamous cell carcinomas (SCC) of diverse anatomical localization. Tissue microarrays (TMA) of 124 SCC were created, immunostained, and analyzed following whole slide digitalization using the Pannoramic Scan and the TMA Module software (3DHISTECH Kft, Budapest, Hungary). Statistical analysis of scoring results was carried out using Pearson's chi-square test. We observed the significant elevation of p16(ink4) and Ki67 expression in supraglottic, tonsillar and tonsillo-lingual SCCs compared to those affecting the oral cavity, oropharynx without tonsils, larynx without supraglottis and the hypopharynx. This differential antigen expression may reflect the diverse route of embryologic differentiation followed by the affected regions except those of the tonsils and the supraglottis which show similar antigenic pattern but diverse developmental path. All the other biomarkers tested including p53, collagen XVII and EGFR were detected in the majority of cancers including high grade cases, but did not reveal any significant regional difference. Based on our results oropharyngeal squamous cell carcinomas may not be regarded as one entity. Concerning the oral cavity and the oropharynx, cancers affecting the tonsils (palatine and lingual) show significantly elevated p16(ink4) and Ki67 expression; so as the cancers of the supraglottis compared to the rest of larynx. Consequently, tonsillar and supraglottic cancers show similar biomarker profiles. Correlation of differential biomarker expression with diverse biological behavior in head and neck cancers need further investigations.