Theraputic targeting of Trk supresses tumor proliferation and enhances cisplatin activity in HNSCC

A Genome Wide CRISPR Proling Approach Identies Mechanisms of Cisplatin Resistance in Head and Neck Squamous Cell Carcinoma

Background

Head and neck squamous cell carcinoma (HNSCC) is a lethal disease with poor survival rates, especially for cancers arising in the oral cavity or larynx. Cisplatin is a key chemotherapeutic for HNSCC; however poor survival rates may be partially due to cisplatin resistance observed in some HNSCCs. Here, we examined the utility of genome-wide CRISPR knockout profiling for nominating pivotal mechanisms of cisplatin resistance in HNSCC models.

Methods

We characterized the cisplatin sensitivity of 18 HNSCC cell lines. Next, we used a genome-wide CRISPR/Cas9 library to identify genes involved in cisplatin resistance. We next performed validation assays in the UM-SCC-49 cell line model.

Results

Our data prioritized 207 genes as pivotal for cisplatin resistance in HNSCC, including novel genes VGLL3, CIRHA1, NCOR1, SPANXA1, MAP2K7, ULK1, and CDK16. Gene set enrichment analysis identified several NOTCH family genes comprising the top pathway driving cisplatin resistance, which we then validated using a targeted NOTCH1 knockout model. Interestingly, we noted that HNSCC models with natural NOTCH pathway alterations including single allele mutations and/or frameshift alterations had diverse responses to cisplatin treatment suggesting that complex and multi-faceted mechanisms contribute to cisplatin resistance in HNSCC.

Conclusions

Collectively, our study validates a genome-wide CRISPR/Cas9 approach for the discovery of resistance mechanisms in HNSCC, adds to the growing evidence that NOTCH1 status should be evaluated as a biomarker of cisplatin response and provides a framework for future work aimed at overcoming cisplatin resistance.

Treatment effects of the EGFR pathway drugs on head and neck cancer stem cells

(1) Head and neck cancer (HNC) is the sixth most common cancer worldwide and show low survival rates and drug resistance, which can be due to the presence of cancer stem cells (CSCs), a small cell population with metastatic potential, invasion and self-renewal ability. (2) Here, seven tumor cells were sorted as CD44+/CD117+/CD133+ or ALDH+, considered as HNC stem cells (HNCSCs), and as CD44-/CD117-/CD133- or ALDH-, considered non-HNCSCs after both cells sorted criteria was compared to evaluate cell migration, invasion, and colony forming assays. These subpopulations were treated with Cetuximab, Paclitaxel, or a combination of both drugs and evaluated for cell viability. Quantitative PCR and western blot were performed to evaluate EGFR, TRKB, KRAS and HIF-1α gene and protein expression. (3) HNCSCs presented more colonies and appeared to be more sensitive to the drug combination when compared with non-HNCSCs, regardless cells sorted criteria and primary tumor subsite. The EGFR, TRKB, KRAS and HIF-1α genes and proteins were upregulated in CSCs compared with non-HNCSCs, thus explaining the drug resistance. (4) This study contributes to the better development of specific therapeutic protocols based on Cetuximab and Paclitaxel drugs in the treatment of HNC in the presence of CSCs and cell proliferation biomarkers.

Overview on Molecular Biomarkers for Laryngeal Cancer: Looking for New Answers to an Old Problem

Laryngeal squamous cell cancer (LSCC) accounts for almost 25-30% of all head and neck squamous cell cancers and is clustered according to the affected districts, as this determines distinct tendency to recur and metastasize. A major role for numerous genetic alterations in driving the onset and progression of this neoplasm is emerging. However, major efforts are still required for the identification of molecular markers useful for both early diagnosis and prognostic definition of LSCC that is still characterized by significant morbidity and mortality. Non-coding RNAs appear the most promising as they circulate in all the biological fluids allowing liquid biopsy determination, as well as due to their quick and characteristic modulation useful for non-invasive detection and monitoring of cancer. Other critical aspects are related to recent progress in circulating tumor cells and DNA detection, in metastatic status and chemo-refractoriness prediction, and in the functional interaction of LSCC with chronic inflammation and innate immunity. We review all these aspects taking into account the progress of the technologies in the field of next generation sequencing.

Molecular and Cellular Mechanisms of Perineural Invasion in Oral Squamous Cell Carcinoma: Potential Targets for Therapeutic Intervention

Simple Summary

Squamous cell carcinoma is the most common type of oral cavity cancer. It can spread along and invade nerves in a process called perineural invasion. Perineural invasion can increase the chances of tumor recurrence and reduce survival in patients with oral cancer. Understanding how oral cancer interacts with nerves to facilitate perineural invasion is an important area of research. Targeting key events that contribute to perineural invasion in oral cavity cancer may reduce tumor recurrence and improve survival. In this review, we describe the impact of perineural invasion in oral cancer and the mechanisms that contribute to perineural invasion. Highlighting the key events of perineural invasion is important for the identification and testing of novel therapies for oral cancer with perineural invasion.

Abstract

The most common oral cavity cancer is squamous cell carcinoma (SCC), of which perineural invasion (PNI) is a significant prognostic factor associated with decreased survival and an increased rate of locoregional recurrence. In the classical theory of PNI, cancer was believed to invade nerves directly through the path of least resistance in the perineural space; however, more recent evidence suggests that PNI requires reciprocal signaling interactions between tumor cells and nerve components, particularly Schwann cells. Specifically, head and neck SCC can express neurotrophins and neurotrophin receptors that may contribute to cancer migration towards nerves, PNI, and neuritogenesis towards cancer. Through reciprocal signaling, recent studies also suggest that Schwann cells may play an important role in promoting PNI by migrating toward cancer cells, intercalating, and dispersing cancer, and facilitating cancer migration toward nerves. The interactions of neurotrophins with their high affinity receptors is a new area of interest in the development of pharmaceutical therapies for many types of cancer. In this comprehensive review, we discuss diagnosis and treatment of oral cavity SCC, how PNI affects locoregional recurrence and survival, and the impact of adjuvant therapies on tumors with PNI. We also describe the molecular and cellular mechanisms associated with PNI, including the expression of neurotrophins and their receptors, and highlight potential targets for therapeutic intervention for PNI in oral SCC.

Impacts of Environmental Factors on Head and Neck Cancer Pathogenesis and Progression

Epidemiological and clinical studies over the past two decades have provided strong evidence that genetic elements interacting with environmental components can individually and collectively influence one’s susceptibility to cancer. In addition to tumorigenic properties, numerous environmental factors, such as nutrition, chemical carcinogens, and tobacco/alcohol consumption, possess pro-invasive and pro-metastatic cancer features. In contrast to traditional cancer treatment, modern therapeutics not only take into account an individual’s genetic makeup but also consider gene–environment interactions. The current review sharpens the focus by elaborating on the impact that environmental factors have on the pathogenesis and progression of head and neck cancer and the underlying molecular mechanisms involved. Recent advances, challenges, and future perspectives in this area of research are also discussed. Inhibiting key environmental drivers of tumor progression should yield survival benefits for patients at any stage of head and neck cancer.

Anti-EGFR treatment effects on laryngeal cancer stem cells

Laryngeal cancer (LC) is one of the common head and neck neoplasms and is characterized by resistance to conventional therapy and poor prognosis. This may result from the presence of cancer stem cells (CSCs), which form a small population in tumors with metastatic potential, high invasive capacity, self-renewal, and differentiation. This study aimed to evaluate the effectiveness of 5-fluorouracil and cisplatin individually, as well as the combination of cetuximab and paclitaxel in a CSC subpopulation separated with biomarkers related to tumoral growth (CD44, CD117, and CD133). In addition, expression of TrkB, KRAS, HIF-1α, and VEGF-A genes and proteins related to cell proliferation were evaluated in this subpopulation. The CD44, CD133, and CD117 biomarkers were used to analyze the identification and separation of both subpopulations using FACSAria Fusion. Subpopulations positive for CD44, CD133, and CD117 or lacking these biomarkers were classified as laryngeal cancer stem cells (LCSCs) or laryngeal cancer non-stem cells (non-LCSCs), respectively. Matrigel invasion and colony forming assays were performed to confirm CSC presence. Subpopulations were cultured and exposed to 5-fluorouracil, cisplatin, and cetuximab/paclitaxel drugs for 24 h. Cell proliferation was determined using MTS assay. KRAS and TrkB gene expression levels were evaluated using quantitative real time PCR with TaqMan® Assay in both subpopulations. The non-LCSC subpopulation was considered as the control for relative expression. We found that the LCSC subpopulation demonstrated more resistance to cetuximab and paclitaxel combination chemotherapy when compared with the non-LCSC subpopulation of the cell line. These LCSC subpopulations presented up-regulated expression of KRAS, HIF-1α, and VEGF-A genes and proteins and no TrkB gene expression, but TrkB protein expression was up-regulated in the LC cell line when compared to the non-CSC subpopulation. "In conclusion, the combination of CD44, CD133, and CD117 biomarkers has stem cell properties. Moreover, LCSCs, are capable of resisting treatment and present high KRAS, HIF-1α, and VEGF-A gene expression".

Nerves in the Tumor Microenvironment: Origin and Effects

Studies have reported the vital role of nerves in tumorigenesis and cancer progression. Nerves infiltrate the tumor microenvironment thereby enhancing cancer growth and metastasis. Perineural invasion, a process by which cancer cells invade the surrounding nerves, provides an alternative route for metastasis and generation of tumor-related pain. Moreover, central and sympathetic nervous system dysfunctions and psychological stress-induced hormone network disorders may influence the malignant progression of cancer through multiple mechanisms. This reciprocal interaction between nerves and cancer cells provides novel insights into the cellular and molecular bases of tumorigenesis. In addition, they point to the potential utility of anti-neurogenic therapies. This review describes the evolving cross-talk between nerves and cancer cells, thus uncovers potential therapeutic targets for cancer.

Construction of an 11-microRNA-based signature and a prognostic nomogram to predict the overall survival of head and neck squamous cell carcinoma patients

Background

Head and neck squamous cell carcinoma (HNSCC) is a fatal malignancy owing to the lack of effective tools to predict overall survival (OS). MicroRNAs (miRNAs) play an important role in HNSCC occurrence, development, invasion and metastasis, significantly affecting the OS of patients. Thus, the construction of miRNA-based risk signatures and nomograms is desirable to predict the OS of patients with HNSCC. Accordingly, in the present study, miRNA sequencing data of 71 HNSCC and 13 normal samples downloaded from The Cancer Genome Atlas (TCGA) were screened to identify differentially expressed miRNAs (DEMs) between HNSCC patients and normal controls. Based on the exclusion criteria, the clinical information and miRNA sequencing data of 67 HNSCC samples were selected and used to establish a miRNA-based signature and a prognostic nomogram. Forty-three HNSCC samples were assigned to an internal validation cohort for verifying the credibility and accuracy of the primary cohort. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to explore the functions of 11 miRNA target genes.

Results

In total, 11 DEMs were successfully identified. An 11-miRNA risk signature and a prognostic nomogram were constructed based on the expression levels of these 11 DEMs and clinical information. The signature and nomogram were further validated by calculating the C-index, area under the curve (AUC) in receiver-operating characteristic curve analysis, and calibration curves, which revealed their promising performance. The results of the internal validation cohort shown the reliable predictive accuracy both of the miRNA-based signature and the prognostic nomogram. GO and KEGG analyses revealed that a mass of signal pathways participated in HNSCC proliferation and metastasis.

Conclusion

Overall, we constructed an 11-miRNA-based signature and a prognostic nomogram with excellent accuracy for predicting the OS of patients with HNSCC.

Role of Tropomyosin-related kinase B receptor and brain-derived neurotrophic factor in cancer

The tropomyosin-related kinase B (TrkB) receptor is a member of the neurotrophic tyrosine kinase receptors family and, together with the brain-derived neurotrophic factor (BDNF), plays an important role in the development of breast cancer, lung cancer, neuroblastoma, colorectal cancer, leukemia, cervical cancer, gallbladder cancer, gastric cancer, kidney cancer, Ewing's sarcoma, esophageal cancer, and head and neck cancer. Overexpression of these two factors has been associated with increased processes involved in carcinogenesis, such as invasion, migration, epithelial-mesenchymal transition (EMT), angiogenesis, metastasis, cell proliferation, resistance to apoptosis, resistance to cell death due to loss of adhesion (anoikis), activation of cell proliferation pathways, regulation of tumor suppressor genes, and drug resistance, and is related to advanced clinical stage. Inhibition of the TrkB/BDNF axis using drugs in phase 1 studies, approved drugs, and small interfering RNA (siRNA) are promising strategies for the treatment of various malignant tumors in addition to increasing the sensitivity of cells resistant to chemotherapy, improving the effectiveness of drugs without increasing toxicity. Another factor related to poor cancer prognosis is the presence of cancer stem cells, having effects similar to the high expression of the TrkB/BDNF axis, on cancer. This review aimed to show the role of the TrkB/BDNF axis in several types of cancer, its possible use as a prognostic biomarker, the effects of inhibiting this axis, and its role in the cancer stem cells.

Inhibition of tropomyosine receptor kinase B on the migration of human Schwann cell and dispersion of oral tongue squamous cell carcinoma in vitro

BACKGROUND

Schwann cells (SC) may play an important role in perineural invasion (PNI) by promoting cancer cell dispersion. Brain-derived neurotrophic factor (BDNF) may contribute to these cellular events by activating tropomyosine receptor kinase B (TrkB). This study examines the effect of TrkB inhibition on SC migration and oral cancer cell dispersion in vitro.

METHODS

Human tongue squamous cell carcinoma (SCC-9) and human SCs were cocultured in three different conditioned mediums: control, BDNF, and TrkB inhibitor. Cell migration, cancer cell dispersion, and SC dedifferentiation were measured on time-lapse and immunofluorescence images.

RESULTS

Cancer cell migration exceeded SC migration in all conditions. TrkB inhibition promoted SC dedifferentiation and significantly increased SC migration, when compared to BDNF conditions. TrkB inhibition also reduced cancer cell dispersion, when compared to control and BDNF-treated cultures.

CONCLUSION

SCs may have importance in the pathophysiology of PNI. TrkB inhibition may be a potential avenue for therapeutic intervention.

Relevance of Neurotrophin Receptors CD271 and TrkC for Prognosis, Migration, and Proliferation in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and often has a poor prognosis. The present study investigated the role of the low affinity nerve growth factor receptor CD271 as a putative therapy target in HNSCC. Neurotrophins that bind to CD271 also have a high affinity for the tropomyosin receptor kinase family (Trk), consisting of TrkA, TrkB, and TrkC, which must also be considered in addition to CD271. A retrospective study and functional in vitro cell line tests (migration assay and cell sorting) were conducted in order to evaluate the relevance of CD271 expression alone and with regard to Trk expression. CD271 and Trks were heterogeneously expressed in human HNSCC. The vast majority of tumors exhibited CD271 and TrkA, whereas only half of the tumors expressed TrkB and TrkC. High expression of CD271-positive cells predicted a bad clinical outcome of patients with HNSCC and was associated with distant metastases. However, the human carcinomas that also expressed TrkC had a reduced correlation with distant metastases and better survival rates. In vitro, CD271 expression marked a subpopulation with higher proliferation rates, but proliferation was lower in tumor cells that co-expressed CD271 and TrkC. The CD271 inhibitor LM11A 31 suppressed cell motility in vitro. However, neither TrkA nor TrkB expression were linked to prognosis or cell proliferation. We conclude that CD271 is a promising candidate that provides prognostic information for HNSCC and could be a putative target for HNSCC treatment.

Prognostic and predictive markers for perineural and bone invasion of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a growing problem worldwide. Several biological and molecular criteria have been established for making a prognosis of OSCC. One of the most important factors affecting the risk of tumor recurrence and overall prognosis is perineural invasion and bone invasion. Perineural invasion is defined as a tumor spreading and the ability of tumor cells to penetrate around or through the nerve tissue. Perineural invasion can cause the tumor to spread to distant areas from the primary tumor location. One possible explanation for this is the formation of microenvironment in the perineural space which may contain cellular factors that act on both nerve tissue and some types of tumor tissues. Bone invasion by OSCC has major implications for tumor staging, choice of treatment, outcome and quality of life. Oral SCCs invade the mandibular or maxillary bone through an erosive, infiltrative or mixed pattern that correlates with clinical behavior. Bone resorption by osteoclasts is an important step in the process of bone invasion by oral SCCs. Some cytokines (e.g. TNFα and PTHrP) lead to receptor activator of NF-κB ligand (RANKL) expression or osteoprotegerin (OPG) suppression in oral SCC cells and in cancer stromal cells to induce osteoclastogenesis. Oral SCCs provide a suitable microenvironment for osteoclastogenesis to regulate the balance of RANKL and OPG. A more molecular-based clinical staging and tailor-made therapy would benefit patients with bone invasion by OSCC.

A subtype of oral, laryngeal, esophageal, and lung, squamous cell carcinoma with high levels of TrkB-T1 neurotrophin receptor mRNA

Background

The NTRK2 genetic locus encodes neurotrophin membrane receptors that play an important role in normal neural tissue plasticity, growth, and survival. One NTRK2-encoded protein is TrkB-FL, which can regulate multiple pathways relevant to cancer. A second NTRK2 gene mRNA isoform encodes TrkB-T1, a receptor that has a different cytoplasmic domain encoded in a mRNA with a unique 3′ terminal exon.

Method

Tumors from The Cancer Genome Atlas (TCGA) and other studies were classified according to the expression of a single form of NTRK2 mRNA, TrkB-T1, identified by its unique 3′ terminal exon. Analysis of differentially expressed genes in TrkB-T1 high expressers was done to determine if tumors enriched for TrkB-T1 mRNA were a uniform group independent of anatomic site.

Results

The mRNA for TrkB-T1 is the most abundant NTRK2 gene mRNA in all squamous cell carcinomas (SCCs) in the TCGA database. Comparison of larynx SCC high TrkB-T1 RNA expressers to low expressers (n = 96) revealed gene expression differences consistent with the high TrkB-T1 tumors being more neural-like. The upregulated genes in the TrkB-T1 RNA high expressers also showed enrichment of pathways involved in retinol metabolism, hedgehog signaling, and the Nfe2l2 response, among other pathways. An examination of oral, esophagus, and lung SCCs (n = 284, 97, 501) showed induction of the same pathways among tumors that expressed high levels of TrkB-T1 mRNA. Proteins associated with regulation of the sonic hedgehog pathway, and the Nfe2l2 response, Tp63, and Keap1 and p62/SQSTM1 proteins, showed differential expression in larynx, oral and lung high TrkB1-T1 expresser SCCs. Unexpectantly, the relationship of high level TrkB-T1 expression to patient outcomes was SCC anatomic site specific. High TrkB-T1 mRNA levels in laryngeal SCC correlated with poor survival, but the opposite was true for lung SCC. This may be because pathways enriched in the TrkB high expressers, like those involving oncogenes NFE2L2, PIK3CA, and SOX2, are known to have SCC anatomic site-specific effects on progression.

Conclusions

High level TrkB-T1 mRNA is a marker of a distinct SCC subtype enriched for at least 3 pathways relevant to tumor progression: Nfe2l2 response, retinol metabolism, and hedgehog signaling.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5789-8) contains supplementary material, which is available to authorized users.

Investigating Trk Protein Expression between Oropharyngeal and Non-oropharyngeal Squamous Cell Carcinoma: Clinical Implications and Possible Roles of Human Papillomavirus Infection

Purpose

The relationship between head and neck squamous cell carcinoma (HNSCC) and subtypes of tropomyosin-related kinase (Trk) has not been studied in-depth. In this study, we evaluated the expression patterns of TrkA, TrkB, and panTrk and their clinicopathological significance as well as association with p16 expression and human papilloma virus (HPV) status.

Materials and Methods

Total of 396 radically resected oropharyngeal (n=121) and non-oropharyngeal (n=275) HNSCCs were included. Immunohistochemistry for TrkA, TrkB, and panTrk was performed. In addition, p16 immunohistochemistry was performed to assess the HPV status. Using HPV-negative HNSCC cell lines, FaDu and CAL27, HPV type 16 E6/E7 gene was transfected, and then changes of TrkA and TrkB expression were analyzed.

Results

In the clinical samples of HNSCC, high expression of TrkA and panTrk were more associated with oropharyngeal and p16 positive squamous cell carcinoma (SCC). In patients with completely resected (R0-resected) oropharyngeal SCC, high TrkA expression was related to superior overall survival and recurrence-free survival (RFS). In patients with R0-resected oral cavity SCC, high panTrk was related to poor RFS. In HPV type E6/E7 gene-transfected FaDu and CAL27 cell lines, increase of TrkA expression was observed.

Conclusion

It seems that expression pattern of panTrk and TrkA differed according to anatomical sites of HNSCC and was closely related to p16 expression and patient prognosis. Trk expression should be considered in the context of anatomical site, p16 expression or HPV status and Trk subtypes.

Is Perineural Invasion of Head and Neck Squamous Cell Carcinomas Linked to Tobacco Consumption?

Perineural invasion (PNI) is an underrecognized path of cancer spread, and its causes and mechanisms are poorly understood. Recent research indicates a mutual attraction of neuronal and cancer cells, largely dependent on neurotrophic factors and their receptors. Interestingly, the release of neurotrophic factors occurs upon cigarette smoke/nicotine exposure in a dose-dependent manner, and serum levels correlate with current smoking, number of smoking years, and smoking severity. Among cell types capable of neurotrophic factors secretion are lung and oral fibroblasts. In our study of 178 patients with head and neck squamous cell carcinoma, tumors of current and former smokers showed PNI significantly more often than tumors of never smokers. Moreover, PNI was a marker for aggressive tumor growth. Surprisingly, PNI was more significant for survival than p16 status. Our study warrants further research on PNI in head and neck squamous cell carcinoma with special emphasis on the impact of tobacco consumption to identify suitable candidates for therapeutic interventions.

TrkB promotes laryngeal cancer metastasis via activation PI3K/AKT pathway

OBJECTIVES

The aim of our study was to investigate the role of TrkB pathway in tumor occurrence and development for in order to provide theoretical basis to laryngeal cancer therapy.

MATERIALS AND METHODS

Biological characteristics of the cells were studied by migration tests and colony forming assay. Gene and protein expression analysis was performed by RT-PCR or western blot. in vivo experiments were conducted in syngeneic BALB/c mice.

RESULTS

Significant changes in protein and gene expression, including higher expression level of TrkB, were found in cells and laryngeal cancer specimens. we demonstrated that TrkB activates AKT via c-Src, leading to increased proliferation. Also, TrkB induced EMT via increased expression of EMT related transcription factors such as Twist-1 and Twist-2.

CONCLUSION

Our data indicate TrkB are overexpressed in laryngeal cancer, and TrkB signaling is involved in tumorigenicity of laryngeal cancer. These observations suggest that TrkB is a promising target for future intervention strategies to prevent tumor metastasis, EMT program in laryngeal cancer.What is already known about this subject?• Cancer of the larynx is one of the most common types of head and neck cancer.• The survival rate of advanced laryngeal cancer is only 30 to 40%.• The tropomyosin-related kinase B receptor (TrkB), together with TrkA and TrkC, are neurotrophin receptors regulating the proliferation and differentiation of neuronal cells.What are the new findings?• TrkB are overexpressed in laryngeal cancer.• TrkB signaling is involved in tumorigenicity of laryngeal cancer.• TrkB acts as a key regulator of the PI3K/AKT signal pathway-mediated tumor metastasis.How might these results change the focus of research or clinical practice?• These observations suggest that TrkB is a promising target for future intervention strategies to prevent tumor metastasis, EMT program in laryngeal cancer. Our study provides molecular insight into the tumor metastasis and has important implications in elucidating oncogenic processes.

Uncovering the role of brain-derived neurotrophic factor/tyrosine kinase receptor B signaling in head and neck malignancies

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors that was first known as responsible for sustain the growth, function, and plasticity of neural cells. BDNF exerts its effects by binding to the tyrosine kinase receptor B (TrkB). The BDNF/TrkB axis has been reported to be overexpressed in several neurogenic and non-neurogenic tumors. Its higher expression was associated with a poor prognosis to patients affected by different human malignancies, tumor growth, invasion, and metastasis; epithelial-mesenchymal transition and resistance to chemotherapy. BDNF/TrkB represent promising targets to the development of novel anticancer therapies. Some clinical trials are currently evaluating the efficacy of Trk protein-target drugs in different types of solid tumors. To date, few groups have evaluated the DNF/TrkB pathway in head and neck malignancies. The aims of this study were to review the literature concerning the role of BDNF/TrkB activation in head and neck squamous cell carcinoma and malignant salivary gland tumors and to discuss future perspectives of BDNF/TrkB-target therapy.

Brain derived neutrophic factor (BDNF) coordinates lympho-vascular metastasis through a fibroblast-governed paracrine axis in the tumor microenvironment

It has long been known that the tumor microenvironment contributes to the proliferation and survival of neoplasms through the constant interaction with the stromal and immune compartments. In this investigation, we explored the role of cancer-associated fibroblasts (CAFs) in the regulation of the tumor microenvironment in head and neck squamous cell carcinoma (HNSCC) though a complex intercellular BDNF-TrkB signaling system. Our studies show that conditioned media derived from patient-derived CAFs promoted HNSCC cell proliferation, in vitro cell migration, cell invasion and chemotherapy resistance, compared to normal fibroblasts. Furthermore, examination of the in vivo impact of CAF pathophysiology in the tumor microenvironment in animal xenograft models revealed that HNSCC cell lines in combination with CAFs promoted tumor growth and increased incidence of lymphovascular metastasis as compared to injection of tumor cells or CAF cells alone. Using pharmacological and genetic alterations, we mechanistically demonstrate the critical importance of BDNF-TrkB signaling in the tumor microenvironment. These investigations further support the rationale for BDNF/TRKB targeted therapy against in the treatment of HNSCC.

Therapeutic Potentials of BDNF/TrkB in Breast Cancer; Current Status and Perspectives

Brain-derived neurotrophic factor (BDNF) is a potent neurotrophic factor that has been shown to stimulate breast cancer cell growth and metastasis via tyrosine kinase receptors TrkA, TrkB, and the p75^NTR death receptor. The aberrant activation of BDNF/TrkB pathways can modulate several signaling pathways, including Akt/PI3K, Jak/STAT, NF-kB, UPAR/UPA, Wnt/β-catenin, and VEGF pathways as well as the ER receptor. Several microRNAs have been identified that are involved in the modulation of BDNF/TrkB pathways. These include miR-206, miR-204, MiR-200a/c, MiR-210, MiR-134, and MiR-191; and these may be of value as prognostic and predictive biomarkers for detecting patients at high risk of developing breast cancer. It has been also been demonstrated that a high expression of genes involved in the BDNF pathway in breast cancer is associated with poor clinical outcome and reduced survival of patients. Several approaches have been developed for targeting this pathway, for example TKr inhibitors (AZD6918, CEP-701) and RNA interference. The aim of the current review was to provide an overview of the role of BDNF/TrkB pathways in the pathogenesis of breast cancer and its value as a potential therapeutic target. J. Cell. Biochem. 118: 2502-2515, 2017. © 2017 Wiley Periodicals, Inc.

microRNA from brush biopsy to characterize oral squamous cell carcinoma epithelium

Few cancers are diagnosed based on RNA expression signatures. Oral squamous cell carcinoma (OSCC) is no exception; it is currently diagnosed by scalpel biopsy followed by histopathology. This study sought to identify oral tumor epithelial microRNA (miRNA) expression changes to determine if these changes could be used to diagnose the disease noninvasively. Analysis of miRNA profiles from surgically obtained OSCC tissue, collected under highly standardized conditions for The Cancer Genome Atlas, was done to determine the potential accuracy in differentiating tumor from normal mucosal tissue. Even when using small 20 subject datasets, classification based on miRNA was 90 to 100% accurate. To develop a noninvasive classifier for OSSC, analysis of brush biopsy miRNA was done and showed 87% accuracy in differentiating tumor from normal epithelium when using RT‐qPCR or miRNAseq to measure miRNAs. An extensive overlap was seen in differentially expressed miRNAs in oral squamous cell carcinoma epithelium obtained using brush biopsy and those reported in saliva and serum of oral squamous cell carcinoma patients in several studies. This suggested that nonselective release of these miRNAs into body fluids from tumor epithelium was largely responsible for the changes in levels in these fluids seen with this disease. Using a variation in mirRPath we identified the KEGG pathway of neurotrophin signaling as a target of these miRNAs disregulated in tumor epithelium. This highlights the utility of brush biopsy of oral mucosa to allow simple acquisition of cancer relevant miRNA information from tumor epithelium.

Neurotrophin signaling in cancer stem cells

Cancer stem cells (CSCs), are thought to be at the origin of tumor development and resistance to therapies. Thus, a better understanding of the molecular mechanisms involved in the control of CSC stemness is essential to the design of more effective therapies for cancer patients. Cancer cell stemness and the subsequent expansion of CSCs are regulated by micro-environmental signals including neurotrophins. Over the years, the roles of neurotrophins in tumor development have been well established and regularly reviewed. Especially, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are reported to stimulate tumor cell proliferation, survival, migration and/or invasion, and favors tumor angiogenesis. More recently, neurotrophins have been reported to regulate CSCs. This review briefly presents neurotrophins and their receptors, summarizes their roles in different cancers, and discusses the emerging evidence of neurotrophins-induced enrichment of CSCs as well as the involved signaling pathways.

TrkB Promotes Breast Cancer Metastasis via Suppression of Runx3 and Keap1 Expression

In metastatic breast cancer, the acquisition of malignant traits has been associated with the increased rate of cell growth and division, mobility, resistance to chemotherapy, and invasiveness. While screening for the key regulators of cancer metastasis, we observed that neurotrophin receptor TrkB is frequently overexpressed in breast cancer patients and breast cancer cell lines. Additionally, we demonstrate that TrkB expression and clinical breast tumor pathological phenotypes show significant correlation. Moreover, TrkB expression was significantly upregulated in basal-like, claudin-low, and metaplastic breast cancers from a published microarray database and in patients with triple-negative breast cancer, which is associated with a higher risk of invasive recurrence. Interestingly, we identified a new TrkB-regulated functional network that is important for the tumorigenicity and metastasis of breast cancer. We demonstrated that TrkB plays a key role in regulation of the tumor suppressors Runx3 and Keap1. A markedly increased expression of Runx3 and Keap1 was observed upon knockdown of TrkB, treatment with a TrkB inhibitor, and in TrkB kinase dead mutants. Additionally, the inhibition of PI3K/AKT activation significantly induced Runx3 and Keap1 expression. Furthermore, we showed that TrkB enhances metastatic potential and induces proliferation. These observations suggest that TrkB plays a key role in tumorigenicity and metastasis of breast cancer cells through suppression of Runx3 or Keap1 and that it is a promising target for future intervention strategies for preventing tumor metastasis and cancer chemoprevention.

The translational significance of epithelial-mesenchymal transition in head and neck cancer

Positive markers of epithelial-mesenchymal transition (EMT) in head and neck cancers complicate clinical management and are associated with reduced survival. We discuss recent translational discoveries in EMT and suggest additional actionable molecular pathways, biomarkers, and clinical agents.

Perineural growth in head and neck squamous cell carcinoma: a review

Perineural growth is a unique route of tumor metastasis that is associated with poor prognosis in several solid malignancies. It is diagnosed by the presence of tumor cells inside the neural space seen on histological or imaging evaluations. Little is known about molecular mechanisms involved in the growth and spread of tumor cells in neural spaces. The poor prognosis associated with perineural growth and lack of targeted approaches necessitates the study of molecular factors involved in communication between tumor and neural cells. Perineural growth rates, shown to be as high as 63% in head and neck squamous cell carcinoma (HNSCC), correlate with increased local recurrence and decreased disease-free survival. Here we describe the literature on perineural growth in HNSCC. In addition, we discuss factors implicated in perineural growth of cancer. These factors include brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 and -4, glial cell-line derived neurotrophic factor (GDNF), the neural cell adhesion molecule (NCAM), substance P (SP), and chemokines. We also explore the literature on membrane receptors, including the Trk family and the low-affinity nerve growth factor receptor. This review highlights areas for further study of the mechanisms of perineural invasion which may facilitate the identification of therapeutic targets in HNSCC.

Epigenetic alterations in metastatic cutaneous carcinoma

BACKGROUND

Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) are the 2 most common cutaneous carcinomas. Molecular profiles predicting metastasis of these cancers have not been identified.

METHODS

Epigenetic profiles of 37 primary cases of cutaneous SCC and BCC were quantified via the Illumina Goldengate Cancer Panel. Differential protein expression by metastatic potential was analyzed in 110 total cases by immunohistochemical (IHC) staining.

RESULTS

Unsupervised hierarchical clustering analysis revealed that metastatic BCCs had a methylation profile resembling cutaneous SCCs. Metastatic cutaneous SCCs were found to be hypermethylated at FRZB (median methylation: 46.7% vs 4.7%; p = 4 × 10(-5) ). Metastatic BCCs were found to be hypomethylated at MYCL2 (median methylation: 3.8% vs 83.4%; p = 1.9 × 10(-6) ). Immunohistochemical staining revealed few differences between metastatic and nonmetastatic cancers.

CONCLUSION

Metastatic primary BCCs and cutaneous SCCs had distinct epigenetic profiles when compared to their nonmetastatic counterparts. Epigenetic profiling may prove useful in future diagnosis and prevention of advanced nonmelanoma skin cancers.

A TrkB-STAT3-miR-204-5p regulatory circuitry controls proliferation and invasion of endometrial carcinoma cells

Background

We previously identified TrkB as an oncogene involved in promoting metastasis in endometrial carcinoma (EC). Here, we sought to delineate the effect of changes in TrkB expression on the global profile of microRNAs (miRNAs) in EC cells and further investigated the correlation between the expression of certain miRNA and TrkB in the clinicopathologic characteristics of EC patients.

Methods and results

Using quantitative reverse transcription-PCR (qRT-PCR), we found that expression of TrkB mRNA has no significant difference in transcript levels between normal endometrium and EC cells captured by laser capture microdissection, while immunohistochemistry results demonstrated a markedly higher expression of TrkB protein in EC tissues. The microRNA array showed that ectopic overexpression and knockdown of TrkB expression caused global changes in miRNA expression in EC cells. qRT-PCR results showed that elevated TrkB repressed miR-204-5p expression in EC cells. Furthermore, immunoblotting assays revealed that TrkB overexpression in Ishikawa^TrkB cells noticeably increased JAK2 and STAT3 phosphorylation, which, however, was aborted by TrkB knockdown in HEC-1B^shTrkB cells. Moreover, ChIP assays showed that phospho-STAT3 could directly bind to STAT3-binding sites near the TRPM3 promoter region upstream of miR-204-5p. Interestingly, using bioinformatics analysis and luciferase assays, we identified TrkB was a novel target of miR-204-5p. Functionally, the MTT assays, clonogenic and Transwell assays showed that miR-204-5p significantly suppressed the clonogenic growth, migration and invasion of EC cells. Furthermore, miR-204-5p also inhibited the growth of tumor xenografts bearing human EC cells. Importantly, we found lower miR-204-5p expression was associated with advanced FIGO stages, lymph node metastasis and probably a lower chance for survival in EC patients.

Conclusions

This study uncovers a new regulatory loop involving TrkB/miR-204-5p that is critical to the tumorigenesis of EC and proposes that reestablishment of miR-204-5p expression could be explored as a potential new therapeutic target for this disease.

Anti-cancer effect of HS-345, a new tropomyosin-related kinase A inhibitor, on human pancreatic cancer

Tropomyosin-related kinase A (TrkA) is emerging as an important player in carcinogenic progression. TrkA overexpression, which is associated with cell growth, proliferation, survival, and invasion, has been observed in pancreatic cancer. We therefore synthesized HS-345, a novel TrkA inhibitor, and evaluated its anti-cancer effect and underlying mechanism of action in pancreatic cancer. In this study, HS-345 effectively inhibited the growth and proliferation in three pancreatic cancer cell lines (PANC-1, MIA PaCa-2, and BxPC-3). Activation of the TrkA/Akt signal cascade was also inhibited by HS-345 treatment in a dose-dependent manner. The pro-apoptotic effect of HS-345 was evidenced by increased levels of cleaved caspase-3 and cleaved PARP, and decrease of Bcl/Bax expression via mitochondria membrane potential, as well as elevated numbers of TUNEL-positive apoptotic cells. HS-345 was additionally found to exert anti-angiogenic effect by decreasing the expression of HIF-1α and VEGF, major factors of angiogenesis, which were also demonstrated by the suppression of tube formation and migration of VEGF-treated human umbilical vein endothelial cells along with inhibition of blood vessel formation by HS-345 in a Matrigel plug assay with mice. Results of our investigation show that HS-345 inhibited the TrkA/Akt signaling pathway resulting in cell growth/angiogenesis inhibition and apoptosis induction. Based on our data, we suggest that HS-345 is a potential candidate for treating pancreatic cancer.

Antitumor activity of AZ64 via G2/M arrest in non-small cell lung cancer

AZ64 is a novel antitumor agent designed as a tropomyosin-related kinase (Trk) inhibitor; however, its effect on lung cancer and its mechanism of action remain unclear. This study aimed to elucidate the antitumor activity of AZ64 and its mechanism of action against non-small cell lung cancer (NSCLC). Our results demonstrate that AZ64 has a potent anti-proliferative effect on NSCLC cells and acts in a dose- and time-dependent manner. We also demonstrate that AZ64 suppresses the anchorage-independent growth and invasion of NSCLC cells. In vivo experiments demonstrated that AZ64 significantly reduced the tumor growth of NSCLC xenografts in nude mice and was well-tolerated. Mechanistic experiments revealed that AZ64 induced the G2/M arrest of NSCLC cells by the accumulation of phospho-cdc2 (Tyr15) at the G2/M transition, following the downregulation of Cdc25C expression. Collectively, our data demonstrate that AZ64 is a potential antitumor drug that may be used for the treatment of NSCLC, which functions by targeting the G2/M transition via the inhibition of the dephosphorylation of phospho-cdc2 (Tyr15).

AZ64 inhibits TrkB and enhances the efficacy of chemotherapy and local radiation in neuroblastoma xenografts

Neuroblastoma is a common pediatric tumor characterized by clinical heterogeneity. Because it is derived from sympathetic neuroblasts, the NTRK family of neurotrophin receptors plays an integral role in neuroblastoma cell survival, growth, and differentiation. Indeed, high expression of NTRK1 is associated with favorable clinical features and outcome, whereas expression of NTRK2 and its ligand, brain-derived neurotrophic factor (BDNF), are associated with unfavorable features and outcome. AZ64 (Astra Zeneca) is a potent and selective inhibitor of the NTRK tyrosine kinases that blocks phosphorylation at nanomolar concentrations. To determine the preclinical activity of AZ64, we performed intervention trials in a xenograft model with NTRK2-overexpressing neuroblastomas. AZ64 alone significantly inhibited tumor growth compared to vehicle-treated animals (p = 0.0006 for tumor size). Furthermore, the combination of AZ64 with conventional chemotherapeutic agents, irinotecan and temozolomide (irino-temo), showed significantly enhanced anti-tumor efficacy compared to irino-temo alone [(p < 0.0001 for tumor size, p < 0.0005 for event-free survival (EFS)]. We also assessed the combination of AZ64 and local radiation therapy (RT) on a neuroblastoma hindlimb xenograft model, and the efficacy of local RT was significantly increased when animals were treated simultaneously with AZ64 (p < 0.0001 for tumor size, p = 0.0006 for EFS). We conclude that AZ64 can inhibit growth of NTRK-expressing neuroblastomas both in vitro and in vivo. More importantly, it can significantly enhance the efficacy of conventional chemotherapy as well as local RT, presumably by inhibition of the NTRK2/BDNF autocrine survival pathway.

A novel role for BDNF-TrkB in the regulation of chemotherapy resistance in head and neck squamous cell carcinoma

Mechanisms of resistance for HNSCC to cisplatin (CDDP), the foundational chemotherapeutic agent in the treatment of this disease, remain poorly understood. We previously demonstrated that cisplatin resistance (CR) can be overcome by targeting Trk receptor. In the current study, we explored the potential mechanistic role of the BDNF-TrkB signaling system in the development of CDDP resistance in HNSCC. Utilizing an in vitro system of acquired CR, we confirmed a substantial up-regulation of both BDNF and TrkB at the protein and mRNA levels in CR cells, suggesting an autocrine pathway dysregulation in this system. Exogenous BDNF stimulation led to an enhanced expression of the drug-resistance and anti-apoptotic proteins MDR1 and XiAP, respectively, in a dose-dependently manner, demonstrating a key role for BDNF-TrkB signaling in modulating the response to cytotoxic agents. In addition, modulation of TrkB expression induced an enhanced sensitivity of cells to CDDP in HNSCC. Moreover, genetic suppression of TrkB resulted in changes in expression of Bim, XiAP, and MDR1 contributing to HNSCC survival. To elucidate intracellular signaling pathways responsible for mechanisms underlying BDNF/TrkB induced CDDP-resistance, we analyzed expression levels of these molecules following inhibition of Akt. Inhibition of Akt eliminated BDNF effect on MDR1 and Bim expression in OSC-19P cells as well as modulated expressions of MDR1, Bim, and XiAP in OSC-19CR cells. These results suggest BDNF/TrkB system plays critical roles in CDDP-resistance development by utilizing Akt-dependent signaling pathways.

KiSS1 mediates platinum sensitivity and metastasis suppression in head and neck squamous cell carcinoma

Although surgery and radiotherapy have been the standard treatment modalities for head and neck squamous cell carcinoma (HNSCC), the integration of cisplatin (CDDP)-based therapy has led to improvements in local and regional control of disease for patients. However, many trials show that only 10-20% of patients benefit from this treatment intensification, which can result in profound treatment-associated morbidity and mortality. Moreover, the marginal survival improvement suggests that CDDP resistance is an innate characteristic of HNSCC. To elucidate the biological mechanisms underpinning CDDP resistance in HNSCC, we utilized an experimental model of CDDP resistance in this disease. We first observed significant enhancements in local tumor growth and metastasis, as well as adverse survival, in CDDP-resistant (CR) tumors compared with sensitive tumors. To elucidate the molecular mechanisms of this phenotype, we undertook a systems biology-based approach utilizing high-throughput PCR arrays, and we identified a significant suppression of KiSS1 mRNA and protein expression in the CR cells, but no significant regions of genomic loss with array comparative genomic hybridization. Genetic suppression of KiSS1 in CDDP-sensitive cell lines rendered them CR, an observation that was mechanistically linked to alterations in glutathione S-transferase-π expression and function. We next confirmed that, in human HNSCC tumors, loss of KiSS1 expression was associated with metastatic human HNSCC tumors compared with non-metastatic tumors. Genetic reconstitution of KiSS1 in CR cells abrogated cellular migration and induced CDDP sensitivity. To confirm these findings in a murine model, either CR or KiSS1-transfected CR cells were studied in an orthotopic model of HNSCC, or survival studies revealed significant improvement in survival of the mice bearing CR-KiSS1 tumors. Mechanistically, alterations in apoptotic pathways and CDDP metabolism contributed to KiSS1-associated chemotherapy sensitization. These studies provided further direct evidence for the role of KiSS1 loss in biologically aggressive HNSCC and suggest potential targets for therapy in CR cancers.