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

Circulating interleukin-8 and osteopontin are promising biomarkers of clinical outcomes in advanced melanoma patients treated with targeted therapy

BACKGROUND

Circulating cytokines can represent non-invasive biomarkers to improve prediction of clinical outcomes of cancer patients. Here, plasma levels of IL-8, CCL4, osteopontin, LIF and BDNF were determined at baseline (T0), after 2 months of therapy (T2) and, when feasible, at progression (TP), in 70 melanoma patients treated with BRAF and MEK inhibitors. The association of baseline cytokine levels with clinical response, progression-free survival (PFS) and overall survival (OS) was evaluated.

METHODS

Cytokine concentrations were measured using the xMAP technology. Their ability to discriminate between responding (Rs) and non-responding (NRs) patients was assessed by Receiver Operating Characteristics analysis. PFS and OS were estimated with the Kaplan-Meier method. The Cox proportional hazard model was used in the univariate and multivariate analyses to estimate crude and adjusted hazard ratios with 95% confidence intervals.

RESULTS

CCL4 and LIF were undetectable in the majority of samples. The median osteopontin concentration at T0 and T2 was significantly higher in NRs than in Rs. The median T0 and T2 values of IL-8 were also higher in NRs than in Rs, although the statistical significance was not reached. No differences were detected for BDNF. In 39 Rs with matched T0, T2, and TP samples, osteopontin and IL-8 significantly decreased from T0 to T2 and rose again at TP, while BDNF levels remained unchanged. In NRs, none of the cytokines showed a significant decrease at T2. Only osteopontin demonstrated a good ability to discriminate between Rs and NRs. A high IL-8 T0 level was associated with significantly shorter PFS and OS and higher risk of progression and mortality, and remained an independent negative prognostic factor for OS in multivariate analysis. An elevated osteopontin T0 concentration was also significantly associated with worse OS and increased risk of death. Patients with high IL-8 and high osteopontin showed the lowest PFS and OS, and in multivariate analysis this cytokine combination remained independently associated with a three- to six-fold increased risk of mortality.

CONCLUSION

Circulating IL-8 and osteopontin appear useful biomarkers to refine prognosis evaluation of patients undergoing targeted therapy, and deserve attention as potential targets to improve its clinical efficacy.

Distinctive mesenchymal-like neurofibroma stem cells shape NF1 clinical phenotypes controlled by BDNF microenvironment

BACKGROUND

Neurofibroma type I (NF1) often presents with multiple clinical phenotypes due to mutations of NF1 gene. The aim of this study was to determine the phenotypic and therapeutic relevance of tumor microenvironment in NF1 patients.

METHODS

Tumor stem cells (TSCs) from NF1 were isolated and cultured using fluorescence activated cell sorting (FACS) and colony formation experiments. Then, flow cytometry was used to detect the surface markers, osteogenic and adipogenic differentiation were performed as well. Its tumorigenesis ability was confirmed by subcutaneous tumorigenesis in nude mice. Immunohistochemical staining was performed on neurofibroma tissues from the head and trunk with different phenotypes. The expression of BDNF in neurofibroma tissues was detected by Elisa and immunohistochemical staining. Western Blotting was used to detect the expression of p38 MAPK pathway in TSCs. The effect of BDNF neutralizing antibody on the tumorigenesis of TSCs was observed.

RESULTS

Herein, we advocate that NF1 contain a new subgroup of mesenchymal-like neurofibroma stem cells (MNSCs). Such colony-forming MNSCs preserved self-renewal, multiple differentiation and tumorigenic capabilities. More interestingly, the MNSCs isolated from neurofibroma tissues of the same patient with different phenotypes presented site-specific capabilities. Moreover, different levels of brain-derived neurotrophic factor (BDNF) in neurofibroma tissues can impact the MNSCs by activating the TrkB/p38 MAPK pathway. Systemic administration of BDNF neutralizing antibodies inhibited MNSCs' characteristics.

CONCLUSIONS

We demonstrated that BDNF can modulate MNSCs and thereby controlling different tumor phenotypes between the head and trunk regions. Application of BDNF neutralizing antibodies may inhibit p38 MAPK pathway, therefore providing a promising strategy for managing NF1.

Neurotoxic stimulation alters prosaposin levels in the salivary systems of rats

Prosaposin (PSAP), a potent neurotrophic factor, is found in neuronal and non-neuronal tissues and various biological fluids. Neuropathological conditions often alter PSAP production in neural tissues. However, little is known about its alterations in non-neural tissues, particularly in the salivary glands, which are natural reservoirs of various neurotrophic factors. In this study, we explored whether neurotoxic stimulation by kainic acid (KA), a glutamate analog, altered PSAP levels in the salivary system of rats. The results revealed that KA injection did not alter total saliva production. However, KA-induced neurotoxic stimulation significantly increased the PSAP level in the secreted saliva but decreased it in the serum. In addition, KA-induced elevated immunoreactivities of PSAP and its receptors have been observed in the granular convoluted tubule (GCT) cells of the submandibular gland (SMG), a major salivary secretory organ. Indeed, a large number of PSAP-expressing immunogold particles were observed in the secretory granules of the SMG. Furthermore, KA-induced overexpression of PSAP was co-localized with secretogranin in secretory acini (mostly in GCT cells) and the ductal system of the SMG, suggesting the release of excess PSAP from the salivary glands into the oral cavity. In conclusion, the salivary system produces more PSAP during neurotoxic conditions, which may play a protective role in maintaining the secretory function of the salivary glands and may work in distant organs.

N-Acetyl Serotonin Provides Neuroprotective Effects by Inhibiting Ferroptosis in the Neonatal Rat Hippocampus Following Hypoxic Brain Injury

Hypoxic-ischemic encephalopathy is the main cause of infant brain damage, perinatal death, and chronic neonatal disability worldwide. Ferroptosis is a new form of cell death that is closely related to hypoxia-induced brain damage. N-Acetyl serotonin (NAS) exerts neuroprotective effects, but its effects and underlying mechanisms in hypoxia-induced brain damage remain unclear. In the present study, 5-day-old neonatal Sprague-Dawley rats were exposed to hypoxia for 7 days to establish a hypoxia model. Histochemical staining was used to measure the effects of hypoxia on the rat hippocampus. The hippocampal tissue in the hypoxia group showed significant atrophy. Hypoxia significantly increased the levels of prostaglandin-endoperoxide synthase 2 (PTGS2) and the iron metabolism-related protein transferrin receptor 1 (TfR1) and decreased the levels of glutathione peroxidase 4 (GPX4). These changes resulted in mitochondrial damage, causing neuronal ferroptosis in the hippocampus. More importantly, NAS may improve mitochondrial function and alleviate downstream ferroptosis and damage to the hippocampus following hypoxia. In conclusion, we found that NAS could suppress neuronal ferroptosis in the hippocampus following hypoxic brain injury. These discoveries highlight the potential use of NAS as a treatment for neuronal damage through the suppression of ferroptosis, suggesting new treatment strategies for hypoxia-induced brain damage.

Molecular Targets in Salivary Gland Cancers: A Comprehensive Genomic Analysis of 118 Mucoepidermoid Carcinoma Tumors

INTRODUCTION

Salivary gland carcinomas (SGC) are histologically diverse cancers and next-generation sequencing (NGS) to identify key molecular targets is an important aspect in the management of advanced cases.

METHODS

DNA was extracted from paraffin embedded tissues of advanced SGC and comprehensive genomic profiling (CGP) was carried out to evaluate for base substitutions, short insertions, deletions, copy number changes, gene fusions and rearrangements. Tumor mutation burden (TMB) was calculated on approximately 1.25 Mb. Some 324 genes in the FoundationOne CDX panel were analyzed.

RESULTS

Mucoepidermoid carcinoma (MECa) mutations were assessed. CDKN2A and CDKN2B GA were common in mucoepidermoid carcinoma (MECa) (52.5 and 30.5%). PIK3CA was also common in MECa (16.9%). ERBB2 amplification/short variants (amp/SV) were found in MECa (5.9/0%). HRAS GA was common in MECa (14.4%) as well. Other targets, including BAP1, PTEN, and KRAS, were noted but had a low incidence. In terms of immunotherapy (IO)-predictive markers, TMB > 10 was more common in MECa (16.9%). PDL1 high was also seen in MECa (4.20%).

CONCLUSION

SGC are rare tumors with no FDA-approved treatment options. This large dataset reveals many opportunities for IO and targeted therapy contributing to the continuously increased precision in the selection of treatment for these patients.

MicroRNA-139-5p acts as a suppressor gene for depression by targeting nuclear receptor subfamily 3, group C, member 1

MicroRNA-139-5p (miR-139-5p) is one of the most differentially expressed miRNAs in the brain between healthy people and depressed patients. However, its function in depression is unclear. Therefore, we investigated the function of miR-139-5p in depression. Here, miR-139-5p expression was found to be upregulated in the model group. MiR-139-5p inhibition could increase sucrose preference and decrease mice immobility time after chronic corticosterone (CORT) injection. Furthermore, compared with the antago-NC group, 3 weeks of antagomiR-139-5p treatment significantly decreased miR-139-5p level in model group hippocampus, increased sucrose preference index, reduced neuron damages, and enhanced the levels of nuclear receptor subfamily 3 group C member 1 (NR3C1), brain-derived neurotrophic factor (BDNF), phosphorylated/total tyrosine kinase receptor B (p-TrkB/TrkB), phosphorylated/total cAMP-response element-binding protein (p-CREB/CREB) and phosphorylated/total extracellular regulated protein kinases (p-ERK/ERK). Moreover, as a potential target for miR-139-5p, NR3C1 level was reduced by miR-139-5p mimic. Altogether, by activating the BDNF-TrkB signaling pathway, miR-139-5p inhibition plays an antidepressant-like role and might serve as an effective depression target (Fig. graphical abstract).

Oral squamous cell carcinoma-released brain-derived neurotrophic factor contributes to oral cancer pain by peripheral tropomyosin receptor kinase B activation

ABSTRACT

Oral cancer pain is debilitating and understanding mechanisms for it is critical to develop novel treatment strategies treatment strategies. Brain-derived neurotrophic factor (BDNF) signaling is elevated in oral tumor biopsies and is involved with tumor progression. Whether BDNF signaling in oral tumors contributes to cancer-induced pain is not known. The current study evaluates a novel peripheral role of BDNF-tropomyosin receptor kinase B (TrkB) signaling in oral cancer pain. Using human oral squamous cell carcinoma (OSCC) cells and an orthotopic mouse tongue cancer pain model, we found that BDNF levels were upregulated in superfusates and lysates of tumor tongues and that BDNF was expressed by OSCC cells themselves. Moreover, neutralization of BDNF or inhibition of TrkB activity by ANA12, within the tumor-bearing tongue reversed tumor-induced pain-like behaviors in a sex-dependent manner. Oral squamous cell carcinoma conditioned media also produced pain-like behaviors in naïve male mice that was reversed by local injection of ANA12. On a physiological level, using single-fiber tongue-nerve electrophysiology, we found that acutely blocking TrkB receptors reversed tumor-induced mechanical sensitivity of A-slow high threshold mechanoreceptors. Furthermore, single-cell reverse transcription polymerase chain reaction data of retrogradely labeled lingual neurons demonstrated expression of full-form TrkB and truncated TrkB in distinct neuronal subtypes. Last but not the least, intra-TG siRNA for TrkB also reversed tumor-induced orofacial pain behaviors. Our data suggest that TrkB activities on lingual sensory afferents are partly controlled by local release of OSCC-derived BDNF, thereby contributing to oral cancer pain. This is a novel finding and the first demonstration of a peripheral role for BDNF signaling in oral cancer pain.

Brain derived neurotrophic factor declines after complete curative resection in gastrointestinal cancer

Background

Brain derived neurotrophic factor (BDNF) is a neurotrophin involved in neural and metabolic diseases, but it is also one of the crucial factors in cancer development and metastases. In the current study, we investigated serum BDNF concentrations in patients that underwent surgical treatment for colorectal cancer or pancreatic cancer.

Methods

Serum BDNF concentrations were measured with standard enzyme-linked immunosorbent assays, before and on the third day after the operation, in 50 consecutive patients with colorectal cancer and 25 patients with pancreatic cancer (tumours in the head of pancreas). We compared pre- and postoperative BDNF levels, according to the subsequent TNM stage, histologic stage, lymph node involvement, neuro- or angio-invasion, and resection range.

Results

In the pancreatic cancer group, BDNF concentrations fell significantly postoperatively (p = 0.011). In patients that underwent resections, BDNF concentrations fell (p = 0.0098), but not in patients that did not undergo resections (i.e., laparotomy alone). There were significant pre- and postoperative differences in BDNF levels among patients with (p = 0.021) and without (p = 0.034) distant metastases. Significant reductions in BDNF were observed postoperatively in patients with small tumours (i.e., below the median size; p = 0.023), in patients with negative angio- or lymphatic invasion (p = 0.028, p = 0.011, respectively), and in patients with lymph node ratios above 0.17 (p = 0.043). In the colon cancer group, the serum BDNF concentrations significantly fell postoperatively in the entire group (p = 0.0076) and in subgroups of patients with or without resections (p = 0.034, p = 0.0179, respectively). Significant before-after differences were found in subgroups with angioinvasions (p = 0.050) and in those without neuroinvasions (p = 0.049). Considering the TNM stages, the postoperative BDNF concentration fell in groups with (p = 0.0218) and without (p = 0.034) distant metastases and in patients with tumours below the median size (p = 0.018).

Conclusion

Our results suggested that BDNF might play an important role in gastrointestinal cancer development. BDNF levels were correlated with tumour volume, and with neuro-, angio- and lymphatic invasions. In pancreatic cancer, BDNF concentrations varied according to the surgical procedure and they fell significantly after tumour resections. Thus, BDNF may serve as a potential marker of complete resections in underdiagnosed patients. However, this hypothesis requires further investigation. In contrast, no differences according to the procedure was made in patients with colon cancer.

BDNF/TrkB/Akt Signaling Pathway Epithelial Odontogenic Tumors and Keratocyst: An Immunohistochemical Study Comparative With Dental Germs

Odontogenic lesions (OL) are an important group of oral and maxillofacial diseases represented by odontogenic cysts, benign, and malignant tumors. The brain-derived neurotrophic factor (BDNF)/ tropomyosin receptor kinase B (TrkB) signaling pathway has multiple biological actions and has been identified as an important pathway in the proliferation, invasion, and survival of different epithelial tumors. Its role in the development of OL, however, has so far been unexplored. Our aim was to evaluate the BDNF/TrkB/Akt/p-RPS6 signaling pathway in OL of epithelial origin. This cross-sectional study comprised 3 cases of tooth germs, 25 cases of odontogenic keratocyst (OK), 29 cases of ameloblastoma (Am), and 6 cases of ameloblastic carcinoma. Immunohistochemical staining for BDNF, TrkB, p-Akt, and p-RPS6 was performed. OLs were evaluated according to the pattern of immunohistochemical expression in epithelial cells and by semiquantitative scores that considered the intensity of staining and percentage of positive cells. BDNF stromal expression was also assessed. No significant differences were observed with respect to the percentage of positive cases for all markers. Regarding the immunoreactive scores, BDNF and p-RPS6 expressions were similar in the odontogenic epithelium of all OL. However, TrkB and p-Akt were overexpressed in OK compared with ameloblastic carcinoma. In Am, epithelial BDNF was significantly higher compared with stromal expression. In conclusion, BDNF seems to participate in the development of cystic, benign, and malignant odontogenic epithelium to similar degrees. The acquisition of the invasive or malignant phenotype in odontogenic neoplasms is not associated with alterations in the BDNF/TrkB/Akt/RPS6 axis, which could be implicated in the differentiation process.

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.

Immunoexpression of BDNF, TrkB, and p75NTR receptors in peripheral neural lesions of the head and neck

BACKGROUND

Brain-derived neurotrophic factor (BDNF) and neurotrophin receptors have been recognized as fundamental regulators of normal brain development, homeostasis, and plasticity. They have also been studied in the behavior of central nervous system tumors. Here, we studied the pattern of BDNF, TrkB and p75NTR immunoexpression in peripheral benign and malignant neural lesions in head and neck.

METHODS

This cross-sectional analytical study included 79 cases of head and neck neural lesions. Nineteen cases of traumatic neuromas (TN), 20 cases of granular cell tumors (GCT), 16 cases of neurofibromas (NF), 20 cases of schwannomas (SC), and 4 malignant peripheral nerve sheath tumor (MPNST) were submitted to immunohistochemistry with BDNF, TrkB, and p75NTR antibodies. A semi-quantitative analysis was performed.

RESULTS

The analysis of BDNF demonstrated a high percentage of positive cells in TN, GCT and SC with a decrease in cases of NF and MPNST. TrkB presented a lower significant immunoexpression in GCT in relation to the TN, NF, SC, and MPNST (P < .0001); and TN showed less percentage of positive cell compared to SC (P = .0017). Regarding p75NTR, the percentage of positive cell was significantly reduced in MPNST compared GCT (P = .009), NF (P = .0138) and SC (P = .0069). Also, a decrease in TN compared to GCT (P = .007) was observed.

CONCLUSIONS

Our results showed the immunoreactivity of BDNF, TrkB, and p75NTR in head and neck peripheral neural lesions. Reduction of BDNF and p75NTR in MPNST might suggest down-regulation during the acquisition of malignant phenotype.

TrkB-Targeted Therapy for Mucoepidermoid Carcinoma

The brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase B (TrkB) pathway was previously associated with key oncogenic outcomes in a number of adenocarcinomas. The aim of our study was to determine the role of this pathway in mucoepidermoid carcinoma (MEC). Three MEC cell lines (UM-HMC-2, H253 and H292) were exposed to Cisplatin, the TrkB inhibitor, ANA-12 and a combination of these drugs. Ultrastructural changes were assessed through transmission electron microscopy; scratch and Transwell assays were used to assess migration and invasion; and a clonogenic assay and spheroid-forming assay allowed assessment of survival and percentage of cancer stem cells (CSC). Changes in cell ultrastructure demonstrated Cisplatin cytotoxicity, while the effects of ANA-12 were less pronounced. Both drugs, used individually and in combination, delayed MEC cell migration, invasion and survival. ANA-12 significantly reduced the number of CSC, but the Cisplatin effect was greater, almost eliminating this cell population in all MEC cell lines. Interestingly, the spheroid forming capacity recovered, following the combination therapy, as compared to Cisplatin alone. Our studies allowed us to conclude that the TrkB inhibition, efficiently impaired MEC cell migration, invasion and survival in vitro, however, the decrease in CSC number, following the combined treatment of ANA-12 and Cisplatin, was less than that seen with Cisplatin alone; this represents a limiting factor.

Neurotrophin Signaling in Medulloblastoma

Neurotrophins are a family of secreted proteins that act by binding to tropomyosin receptor kinase (Trk) or p75NTR receptors to regulate nervous system development and plasticity. Increasing evidence indicates that neurotrophins and their receptors in cancer cells play a role in tumor growth and resistance to treatment. In this review, we summarize evidence indicating that neurotrophin signaling influences medulloblastoma (MB), the most common type of malignant brain cancer afflicting children. We discuss the potential of neurotrophin receptors as new therapeutic targets for the treatment of MB. Overall, activation of TrkA and TrkC types of receptors seem to promote cell death, whereas TrkB might stimulate MB growth, and TrkB inhibition displays antitumor effects. Importantly, we show analyses of the gene expression profile of neurotrophins and their receptors in MB primary tumors, which indicate, among other findings, that higher levels of NTRK1 or NTRK2 are associated with reduced overall survival (OS) of patients with SHH MB tumors.

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.

Identification of Potential Candidate Genes of Oral Cancer in Response to Chronic Infection With Porphyromonas gingivalis Using Bioinformatical Analyses

Recent investigations revealed the relationship between chronic periodontitis, Porphyromonas gingivalis and cancer. However, host genes that change in response to chronic infection with P. gingivalis and may contribute to oral cancer have remained largely unknown. In the present study, we aimed to comprehensively analyze microarray data obtained from the chronic infection model of immortalized oral epithelial cells that were persistently exposed to P. gingivalis for 15 weeks. Using protein-protein interaction (PPI) networks and Ingenuity Pathway Analysis (IPA), we identified hub genes, major biological processes, upstream regulators and genes potentially involved in tumor initiation and progression. We also validated gene expression and demonstrated genetic alteration of hub genes from clinical samples of head and neck cancer. Overall, we utilized bioinformatical methods to identify IL6, STAT1, LYN, BDNF, C3, CD274, PDCD1LG2, and CXCL10 as potential candidate genes that might facilitate the prevention and treatment of oral squamous cell carcinoma (OSCC), the most common type of head and neck squamous cell carcinoma (HNSCC).

Brain-Derived Neurotrophin and TrkB in Head and Neck Squamous Cell Carcinoma

We hypothesized that in head and neck squamous cell carcinoma (HNSCC), the neurotrophin brain-derived neurotrophic factor (BDNF) and its high affinity receptor TrkB regulate tumor cell survival, invasion, and therapy resistance. We used in situ hybridization for BDNF and immunohistochemistry (IHC) for TrkB in 131 HNSCC samples. Brain-derived neurotrophic factor was highly expressed in normal mucosa in HNSCC tissue and in cell lines, whereas only 42.74% of HNSCC tissue was TrkB⁺. One fourth of HNSCC cases was human papilloma virus (HPV)⁻ positive, but the TrkB IHC frequency was not different in HPV-positive (HPV⁺) and negative cases. The UPCI-SCC090 cells expressed constitutive levels of TrkB. Transforming-growth-factor-β1 (1 ng/mL TGF-β1) induced TrkB in a subpopulation of SCC-25 cells. A single 10-µg/mL mitomycin C treatment in UPCI-SCC090 cells induced apoptosis and BDNF did not rescue them. The SCC-25 cells were resistant to the MMC treatment, and their growth decreased after TGF-β1 treatment, but was restored by BDNF if it followed TGF-β1. Taken together, BDNF might be ineffective in HPV⁺ HNSCC patients. In HPV⁻ HNSCC patients, tumor cells did not die after chemotherapeutic challenge and BDNF with TGF-β1 could improve tumor cell survival and contribute to worse patient prognosis.

A gene expression profile associated with perineural invasion identifies a subset of HNSCC at risk of post-surgical recurrence

OBJECTIVES

Perineural invasion (PNI) is a common histopathological finding in head and neck squamous cell carcinoma (HNSCC). We aimed to explore the molecular mechanisms involved in PNI and the role of PNI as an aggressive pathological feature.

MATERIALS AND METHODS

We used data from The Cancer Genome Atlas (TCGA) to relate the histological presentation of 528 HNSCC tumours to clinical, whole genome expression and proteomic data.

RESULTS

We identified a specific gene expression profile highly enriched in genes related to muscle differentiation/function and associated with PNI in HNSCC. We explored the clinical significance of this profile in three groups of HNSCC tumours stratified according to their low, intermediate or high risk of post-surgical recurrence. In the "low-risk" group, defined as tumours indicated for surgery without adjuvant radiotherapy (n = 51), the PNI gene expression profile identified a subset of HNSCC with a higher rate of tumour recurrence, decreased Disease Free Survival (DFS) and Overall Survival (OS) (p < 0.0001 and p = 0.0064, respectively). Comparable results were observed in "intermediate risk" tumours (n = 112), but not in "high risk" tumours (n = 147), whose prognosis was driven by the presence of lymph node extracapsular spread. Finally, we found that tumours with histological PNI had increased activation levels of the Akt/PKB and mTOR (mammalian Target Of Rapamycin) kinases.

CONCLUSION

PNI is characterised by a specific gene expression profile and distinct biological characteristics. Analysing the PNI gene expression profile holds potential for therapeutic stratification of HNSCC and identification of a subset of tumours with a higher risk of recurrence.

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.