TrkA Expression Research Articles

NTRK Gene Expression Analysis in Oral Squamous Cell Carcinoma Mexican Population.

Oral cancer holds the sixth position in malignancies worldwide; 90% correspond to oral squamous cell carcinoma (OSCC). Diverse reports suggest that NTRK genes and their receptors are key oncogenesis regulators to tumor progression in human cancers. Objective: To analyze the NTRK and Trk expression and their association with clinicopathological features of OSCC in Mexican patients' samples. Material and Methods: We analyzed 95 OSCC cases of pan-trk immunoexpression through a software-assisted method. Gene expression was analyzed by RT-qPCR employing the ΔΔCT method. Kruskal-Wallis and Spearman's correlation tests were performed. Results: Our mean age was 62.4 (±16.9) years. A total of 37 cases were tumors in the lateral border of the tongue. Age was significantly associated with the anatomical site. 42% (40 of 95) cases were pan-trk positive. A total of 21 cases showed intense immunoexpression predominantly in poorly differentiated OSCC, with a significant correlation between immunoexpression and age and gender. Gene expression showed that poorly differentiated cases exhibited higher NTRK2 expression, while well-differentiated cases demonstrated NTRK3 significantly higher expression. Conclusions: Our results suggest that NTRK family expression is present in OSCC, with differential expression related to differentiation degree. Additional information about their activation or mutational status could reinforce their potential as a possible primary or adjuvant treatment target.

A temporal (phospho-)proteomic dataset of neurotrophic receptor tyrosine kinase signalling in neuroblastoma

Neurotrophic receptor tyrosine kinases (TrkA, TrkB, TrkC), despite their homology, contribute to the clinical heterogeneity of the childhood cancer neuroblastoma. TrkA expression is associated with low-stage disease and is often seen with spontaneous tumour regression. Conversely, TrkB is present in unfavourable neuroblastomas that often harbour amplification of the MYCN oncogene. The role of TrkC is less clearly defined, although some studies suggest its association with a favourable outcome. Understanding the differences in activity of Trk receptors that drive divergent clinical phenotypes as well as the influence of MYCN amplification on downstream Trk receptor signalling remains poorly understood. Here, we present a comprehensive label-free mass spectrometry-based total proteomics and phosphoproteomics dataset (432 raw files with FragPipe search outputs; available on PRIDE with accession number PXD054441) where we identified and quantified 4,907 proteins, 16,744 phosphosites and 5,084 phosphoproteins, derived from NGF/BDNF/NT-3 treated TrkA/B/C-overexpressing neuroblastoma cells with differential MYCN status. Analysing our dataset offers valuable insights into TrkA/B/C receptor signalling in neuroblastoma and its modulation by MYCN status; and holds potential for advancing therapeutic strategies in this challenging childhood cancer.

Selective, Intrinsically Fluorescent Trk Modulating Probes.

Neurotrophins (NTs) elicit the growth, survival, and differentiation of neurons and other neuroectoderm tissues via activation of Trk receptors. Hot spots for NT·Trk interactions involve three neurotrophin loops. Mimicry of these using "cyclo-organopeptides" comprising loop sequences cyclized onto endocyclic organic fragments accounts for a few of the low molecular mass Trk agonists or modulators reported so far; the majority are nonpeptidic small molecules accessed without molecular design and identified in random screens. It has proven difficult to verify activities induced by low molecular mass substances are due to Trk activation (rather than via other receptors), enhanced Trk expression, enhanced NT expression, or other pathways. Consequently, identification of selective probes for the various Trk receptors (e.g., A, B, and C) has been very challenging. Further, a key feature of probes for early stage assays is that they should be easily detectable, and none of the compounds reported to date are. In this work, we designed novel cyclo-organopeptide derivatives where the organic fragment is a BODIPY fluor and found ones that selectively, though not specifically, activate TrkA, B, or C. One of the assays used to reach this conclusion (binding to live Trk-expressing cells) relied on intrinsic fluorescence in the tested materials. Consequently, this work established low molecular mass Trk-selective probes exhibiting neuroprotective effects.

Expression of Neurotrophic Factors and Their Receptors in the Rat Spinal Trigeminal Nucleus

The spinal trigeminal nucleus as part of the trigeminal sensory nuclear complex is associated with the transmission of discriminative tactile sensations, primarily pain, and temperature, from the orofacial region. It is divided into three parts – caudal, interpolar, and oral subnucleus which process pain and temperature stimulate. Our previous experiments have revealed the presence of certain neurotrophic factors such as the nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) in this nucleus. These neurotrophins facilitate neuronal differentiation, survival, and plasticity by signalling through high-affinity transmembrane receptors. By using primary antibodies against NGF, BDNF, NT-3, and glial-derived neurotrophic factor (GDNF), and their corresponding receptors of the tyrosine receptor kinase (Trk) proto-oncogene family and GFRα1, we found immunoreactive cells scattered along the whole length of the nucleus in rats in all three subnuclei. In particular, we observed that the majority of spinal trigeminal neurons were intensely immunostained for all the neurotrophic factors examined and that they were richly endowed with their Trk receptors. Our results also showed that NGF, NT-3, TrkC and GFRα1 expression did not differ between different topographic regions of the nucleus, while BDNF, GDNF, and TrkA expression was highest in the SpVo, and TrkB expression was highest in the SpVi and SpVc. Given that these neurotrophic factors are involved in mechanisms of central sensitization in trigeminal nociceptive pathways, it can be inferred that neurotrophins may contribute to a better understanding of the fundamental mechanisms of orofacial pain.

Cisplatin induced alterations in nociceptor developmental trajectory elicits a TrkA dependent platinum-based chemotherapy induced neuropathic pain

Cisplatin-based chemotherapy is a common treatment for paediatric cancer. Unfortunately, cisplatin treatment causes neuropathic pain, a highly prevalent adverse health related complication in adult childhood cancer survivors. Due to minimal understanding of this condition, there are currently no condition tailored analgesics available. Here we investigated an alteration in nociceptor maturation that results in neuronal sensitisation and manifestation of cisplatin induced survivorship pain in a TrkA dependent manner. Cisplatin was administered (i.p. 0.1 mg/kg Postnatal day 14 and 16) to neonatal male and female Wistar rats and nociceptive behavioural assays were performed. In vitro studies utilised isolated neonatal dorsal root ganglia sensory neurons treated with cisplatin (5 μg/ml) to elucidate impact upon nociceptor activation and neurite growth, in combination with TrkA inhibition (GW441756 10 nM and 100 nM). Cisplatin treated male and female neonatal Wistar rats developed a delayed but lasting mechanical and heat hypersensitivity. Cisplatin administration led to increased TrkA expression in dorsal root ganglia sensory neurons. Nerve growth factor (NGF) induced TrkA activation led to sensory neuritogenesis and nociceptor sensitisation, which could be prevented through pharmacological TrkA inhibition (GW441756 either s.c. 100 nM or i.p. 2 mg/kg). Administration of TrkA antagonist suppressed cisplatin induced TRPV1 mediated nociceptor sensitisation and prevented cisplatin induced neuropathic pain. These studies provide greater understanding of the underlying mechanisms that cause cisplatin induced childhood cancer survivorship pain and allowing identification of potential therapeutic targets.

Effects of oral administration of nonselective Trk inhibitor on bladder overactivity in rodent models of prostatic inflammation.

Our research focused on the assessment of the impact of systemic inhibition of Trk receptors, which bind to nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), on bladder hypersensitivity in two distinct rodent models of prostatic inflammation (PI). Male Sprague-Dawley rats were divided into three groups (n = 6 each): the control group (no PI, vehicle administration), the untreated group (PI, vehicle administration), and the treated group (PI, nonselective Trk inhibitor, GNF 5837, administration). PI in rats was induced by a intraprostatic injection of 5% formalin. Posttreatment, we carried out conscious cystometry and a range of histological and molecular analyses. Moreover, the study additionally evaluated the effects of a nonselective Trk inhibitor on bladder overactivity in a mouse model of PI, which was induced by prostate epithelium-specific conditional deletion of E-cadherin. The rat model of PI showed upregulations of NGF and BDNF in both bladder and prostate tissues in association with bladder overactivity and inflammation in the ventral lobes of the prostate. GNF 5837 treatment effectively mitigated these PI-induced changes, along with reductions in TrkA, TrkB, TrkC, and TRPV1 mRNA expressions in L6-S1 dorsal root ganglia. Also, in the mouse PI model, GNF 5837 treatment similarly improved bladder overactivity. The findings of our study suggest that Trk receptor inhibition, which reduced bladder hypersensitivity and inflammatory responses in the prostate, along with a decrease in overexpression of Trk and TRPV1 receptors in sensory pathways, could be an effective treatment strategy for male lower urinary tract symptoms associated with PI and bladder overactivity.

Cytotoxic effects of nerve growth factor and its combinations with chemotherapeutic drugs on anaplastoc astrocytoma, glioblastoma and medubloblastoma cells <i>in vitro</i>

BACKGROUND: Currently, the effectiveness of the treatment of malignant tumors using surgical resection, radiotherapy and chemotherapy is insufficient. Therefore, new research is needed to find alternative molecules with antitumor effects. It is known that nerve growth factor (NGF) inhibits invasion, migration, and angiogenesis of tumor cells. Studying the effects of NGF on brain tumors, as well as its combinations with chemotherapy drugs used in medicine, may contribute to the development of new treatment regimens for malignant neoplasms in the central nervous system. AIM: The purpose of this study is an exploration the molecular and cellular mechanisms of anticancer effects of individual and combined preparations of NGF and chemotherapeutic drugs on brain tumor cells (gliomas C6, U251, anaplastic astrocytoma, glioblastoma and medulloblastoma). MATERIALS AND METHODS: The study was performed on rat glioma C6, human U251 glioma cell lines, as well as on primary cells of anaplastic astrocytoma (n = 9), glioblastoma (n = 9) and medulloblastoma (n = 38) patients. The cytotoxicity of chemotherapeutic drugs, NGF and their combinations against tumor cells was assessed using the MTT assay. The expression of TrkA and p75 receptors on anaplastic astrocytoma, glioblastoma and medulloblastoma cells was assessed by immunofluorescence analysis using anti-TrkA and anti-p75 monoclonal antibodies. RESULTS: Nerve growth factor exhibits in vitro cytotoxic activity that exceeds the activity of chemotherapy drugs towards rat glioma C6, human U251, anaplastic astrocytoma (AA), glioblastoma (GBM) and medulloblastoma cells. The cytotoxic activity of NGF in combination with chemotherapy drugs is significantly higher than the activity of the individual NGF drug against medulloblastoma cells, while against anaplastic astrocytoma cells it is comparable to the indicators of the isolated action of NGF, and lower for glioblastoma cells. The effectiveness of the cytotoxic effect of the combinations NGF + cisplatin and NGF + temozolomide (TMZ) on AA and GBM cells correlates with both the expression of TrkA, p75 receptors, and their coexpression, indicating that expression indicators can be considered as markers of tumor cell sensitivity to NGF. CONCLUSIONS: The data obtained allow us to consider NGF as a potential anticancer drug for the treatment of brain tumors. Thus, NGF can act as a potential anticancer drug for the development of new therapeutic regimens for brain tumors.

Primary NTRK -rearranged Spindle Cell Neoplasm of the Gastrointestinal Tract: A Clinicopathological and Molecular Analysis of 8 Cases.

NTRK-rearranged spindle cell neoplasm occurs predominantly in the superficial or deep soft tissues of extremities or trunk. Occurrence in the visceral organs is extremely rare. Herein, we describe 8 cases of NTRK-rearranged spindle cell neoplasm that arose primarily in the gastrointestinal tract. Patients included 5 males and 3 females with age at presentation ranging from 6 to 63 years (median: 29.5 years). Tumors occurred in the colon (n=3), small intestine (n=2), rectum (n=2), and stomach (n=1). Tumor size ranged from 3.5 to 9cm (median: 5cm). Morphologically, 4 tumors were low-grade, composed of haphazard or intertwining fascicles of spindle cells, with prominent interstitial collagen fibers and ring-like perivascular hyalinization being present in 2 tumors. The other 4 tumors were histologically high-grade sarcomas, consisting of sweeping fascicles of atypical spindle cells showing increased cellularity and brisk mitotic activity. Immunohistochemically, 6/6 cases (100%) showed diffuse and strong cytoplasmic staining of pan-TRK. Variable expression of TrkA, CD34, and S100 was noted in 5/5 (100%), 5/8 (62.5%), and 4/7 (57.1%) cases, respectively. Fluorescence in situ hybridization analysis showed NTRK1 rearrangement (n=7) and NTRK2 rearrangement (n=1). In cases with available materials, RNA sequencing identified LMNA::NTRK1 (n=3), TPM3::NTRK1 (n=2), and STRN::NTRK2 (n=1) fusions. At follow-up (range: 4 to 30 months; median: 12.5 months), 6 of 7 patients who underwent surgery had no evidence of disease at last follow-up. One patient was succumbed to the disease at 12 months despite adjunctive treatment with TRK inhibitor larotrectinib after surgery. One patient was treated with larotrectinib alone. He showed significant response at 7 months after treatment. NTRK-rearranged spindle cell neoplasm represents an exceptionally rare entity in the gastrointestinal tract. The presence of interstitial collagen fibers and ring-like perivascular hyalinization and co-expression of CD34 and S100 are diagnostic clues to low-grade neoplasms. However, high-grade sarcomas pose a considerable diagnostic challenge to pathologists owing to the lack of specific features. The final diagnosis relies on molecular assays. Patients with advanced disease may benefit from TRK inhibitor treatment.

NGF Signaling Exacerbates KOA Peripheral Hyperalgesia via the Increased TRPV1-Labeled Synovial Sensory Innervation in KOA Rats.

Knee osteoarthritis (KOA) pain is caused by nociceptors, which are actually sensory nerve fiber endings that can detect stimuli to produce and transmit pain signals, and high levels of NGF in synovial tissue led to peripheral hyperalgesia in KOA. The purpose of this study is to investigate how sensory nerve fibers respond to the NGF/TrKA signal pathway and mediate the peripheral hyperalgesia in KOA rats. Forty SD male rats were randomly divided into 4 groups: normal, KOA, KOA + NGF, and KOA + siRNA TrKA. KOA model rats were induced by anterior cruciate ligament transection (ACLT). Mechanical and cold withdrawal thresholds (MWT and CWT) were measured 4 times in each group. The synovial tissues were harvested on day 28, and the expressions of NGF, TrKA, TRPV1, IL-1β, and PGP9.5 were determined using western blot, qPCR, and immunofluorescence staining. The primary rat fibroblast-like synoviocytes (FLSs) and DRG cells were divided into 4 groups as in vivo. The expressions of NGF, TrKA, TRPV1, and CGRP in vitro were determined using western blot and qPCR. KOA and intra-articular injection with NGF protein increased both mRNA and protein levels, not only TRPV1, PGP 9.5, and IL-1β in the synovial tissue, but also TRPV1, PGP 9.5, and S100 in the DRG tissue, while above changes were partly reversed after siRNA TrKA intervention. Besides, siRNA TrKA could improve peripheral hyperalgesia and decreased the TRPV1 positive nerve fiber innervation in synovial tissue. The results in vitro were consistent with those in vivo. This study showed the activation of the NGF/TrKA signaling pathway in KOA promoted the release of pain mediators, increased the innervation of sensory nerve fibers in the synovium, and worsened peripheral hyperalgesia. It also showed increased TRPV1 positive sensory innervation in KOA was mediated by NGF/TrKA signaling and exacerbated peripheral hyperalgesia.

IMMUNOHISTOCHEMICAL EXPRESSION OF NGF/TrkA AND BDNF/TrkB IN TUMOR PARIENCHYMA AND PERIPROSTATIC ADIPOSE TISSUE, DEPENDING ON THE PATHOANATOMIC STAGE OF PROSTATE CANCER

Introduction: For more than 30 years, the idea of inhibiting growth factors has taken over the minds of different generations of scientists since the progression of the neoplastic process is determined by uncontrolled proliferation differentiation and apotosis and the metastasis of the neoangiogenesis process. The aim: of this work is to show the density of immunohistochemical expression of NGF/TrkA and BDNF/TrkB A Trk B in tumor parienchyma and periprostatic adipose tissue. The study ability is to use it as a prognostic indicator for metastasis of prostate cancer. Material and methods: During the period 2018-2022, 184 patients were diagnosed with radical prostateectomy on the occasion of localized prostate cancer with PSA < or > 20 nmoll/ml, Gleason< or >7, G< or >II. study of the density of expression besch determined by a semi-quantitative method and was established by counting epithelial cells associated with a monocronal antibody, calculated on 20 fields. Results: The study showed expression of Trk receptors in epithelial cells in all tissue samples. NGF/TrkA has poor expression in adipose tissue in areas perirectally and ventrally in the pathoanatomical stage G1, and it becomes moderately positive as the process of undifferentiation progresses. The same tendency is observed in the expression of neurotrophin in prostate-epithelial cells. Conclusions: The increased density of NGF, as well as the preoperative determination of the expression of BDNF and TrK a,b receptors in the pathoantomic preparation, can be used as a negative prognostic indicator of the aggressiveness of the CaP tumor, as well as its possible metastasis.

Effect of electroacupuncture at Neiguan (PC6) at different time points on myocardial ischemia reperfusion arrhythmia in rats.

To observe the effects of electroacupuncture at Neiguan (PC6) at different time points on reperfusion arrhythmia (RA) after myocardial ischemia and reperfusion in rats, and to investigate the correlation of this protective effect with nerve growth factor (NGF), tyrosine kinase A (TrkA), tyrosine hydroxylase (TH), and norepinephrine (NE). METHODS：A total of 72 Sprague-Dawley male rats were randomly divided into six groups (n = 12 rats/group): normal group (Norm), sham operation group (Sham), ischemia reperfusion group (I/R), pre-ischemic electroacupuncture group (EAI), pre-reperfusion electroacupuncture group (EAII), post-reperfusion electroacupuncture group (EAIII). The myocardial ischemia-reperfusion injury (MIRI) model was induced by occlusion of left anterior descending coronary artery for 20 min followed by reperfusion for 40 min in rats. With no intervention in the Norm group and only threading without ligation in the Sham group. Electroacupuncture pre-treatment at 20 min/d for 7 d before ligation in the EAⅠ group, 20 min of electroacupuncture before reperfusion in the EAII group and 20 min of electroacupuncture after reperfusion in the EAIII group. The electrocardiogram (ECG) of each group was recorded throughout the whole process, and the success of the MIRI model was determined based on the changs of J-point and T-wave in the ECG. The arrhythmia score was used to record premature ventricular contractions, ventricular tachycardia and ventricular fibrillation during the reperfusion period to assess the reperfusion induced arrhythmias. The expression levels of NGF, TrkA, TH protein were measured by Western blot. Moreover, the expression levels of plasma and myocardial NE levels were detected by enzyme linked immunosorbent assay. The differences between Norm group and Sham group were not statistically significant in all indexes. Arrhythmia score, myocardial NGF, TrkA, TH, and NE expression were significantly higher in the I/R group compared with the Sham group. Arrhythmia score, myocardial NGF, TrkA, TH, and NE expression were significantly lower in each EA group compared with the I/R group. Electroacupuncture at Neiguan (PC6) at different time points can reduce the incidence and severity of reperfusion arrhythmias in rats. This protective effect is related to electroacupuncture regulating NGF, TrkA, TH, NE expression and reducing sympathetic hyperactivation.

Breaking NGF-TrkA immunosuppression in melanoma sensitizes immunotherapy for durable memory T cell protection.

Melanoma cells, deriving from neuroectodermal melanocytes, may exploit the nervous system's immune privilege for growth. Here we show that nerve growth factor (NGF) has both melanoma cell intrinsic and extrinsic immunosuppressive functions. Autocrine NGF engages tropomyosin receptor kinase A (TrkA) on melanoma cells to desensitize interferon γ signaling, leading to T and natural killer cell exclusion. In effector T cells that upregulate surface TrkA expression upon T cell receptor activation, paracrine NGF dampens T cell receptor signaling and effector function. Inhibiting NGF, either through genetic modification or with the tropomyosin receptor kinase inhibitor larotrectinib, renders melanomas susceptible to immune checkpoint blockade therapy and fosters long-term immunity by activating memory T cells with low affinity. These results identify the NGF-TrkA axis as an important suppressor of anti-tumor immunity and suggest larotrectinib might be repurposed for immune sensitization. Moreover, by enlisting low-affinity T cells, anti-NGF reduces acquired resistance to immune checkpoint blockade and prevents melanoma recurrence.

Brachial Plexus Root Avulsion Injury-Induced Endothelin-Converting Enzyme-Like 1 Overexpression Is Associated with Injured Motor Neurons Survival.

Brachial plexus root avulsion (BPRA) injury arises from challenging delivery during childbirth, sports-related incidents, or car accidents, leading to extensive loss of motor neurons (MNs) and subsequent paralysis, including both motor and sensory impairment. Surgical nerve re-implantation cannot effectively restore motor function, and the survival of injured MNs is vital for axon regeneration and re-innervating the target muscles. Therefore, identifying novel molecular targets to improve injured MNs survival is of great significance in the treatment of BPRA injuries. Endothelin-converting enzyme-like 1 (ECEL1), a membrane-bound metallopeptidase, was initially identified as a molecule associated with nerve injuries. Damaged neurons exhibit a significant increase in the expression of ECEL1 following various types of nerve injuries, such as optic nerve injury and sciatic nerve injury. This study aimed to investigate the relationship between ECEL1 overexpression and the survival of injured MNs following BPRA injury. Our results observed a significant elevation in ECEL1 expression in injured MNs and positively correlated with MNs survival following BPRA injury. The transcription of ECEL1 is regulated by the transcription factors c-Jun and ATF3 in the context of BPRA injury, which is consistent with previous other nerve injuries study. In addition, the expression of TrkA gradually decreases in ECEL1-positive MNs and ECEL1 possibly preserves the activity of downstream AKT-GSK3β pathway of TrkA in injured MNs. In conclusion, our results introduce a promising therapeutic molecular target to assist re-implantation surgery for the treatment of BPRA injury.

Neurotrophin growth factors and their receptors as promising blood biomarkers for Alzheimer's Disease: a gene expression analysis study.

Alzheimer's disease (AD) is a multifaceted neurological ailment affecting more than 50million individuals globally, distinguished by a deterioration in memory and cognitive abilities. Investigating neurotrophin growth factors could offer significant contributions to understanding AD progression and prospective therapeutic interventions. The present investigation collected blood samples from 50 patients diagnosed with AD and 50 healthy individuals serving as controls. The mRNA expression levels of neurotrophin growth factors and their receptors were measured using quantitative PCR. A Bayesian regression model was used in the research to assess the relationship between gene expression levels and demographic characteristics such as age and gender. The correlations between variables were analyzed using Spearman correlation coefficients, and the diagnostic potential was assessed using a Receiver Operating Characteristic curve. NTRK2, TrkA, TrkC, and BDNF expression levels were found to be considerably lower (p-value < 0.05) in the blood samples of AD patients compared to the control group. The expression of BDNF exhibited the most substantial decrease in comparison to other neurotrophin growth factors. Correlation analysis indicates a statistically significant positive association between the genes. The ROC analysis showed that BDNF exhibited the greatest Area Under the Curve (AUC) value of 0.76, accompanied by a sensitivity of 70% and specificity of 66%. TrkC, TrkA, and NTRK2 demonstrated considerable diagnostic potential in distinguishing between cases and controls. The observed decrease in the expression levels of NTRK2, TrkA, TrkC, and BDNF in AD patients, along with the identified associations between specific genes and their diagnostic capacity, indicate that these expressions have the potential to function as biomarkers for the diagnosis and treatment of AD.

Design, synthesis and anticancer evaluation of novel arylhydrazones of active methylene compounds

Nerve growth factor (NGF) and its receptor, tropomyosin kinase receptor kinase type A (TrkA) is emerging as an important target for Glioblastoma (GBM) treatment. TrkA is the cancer biomarker majorly involved in tumor invasion and migration into nearby normal tissue. However, currently, available Trk inhibitors exhibit many adverse effects in cancer patients, thus demanding a novel class of ligands to regulate Trk signaling. Here, we exploited the role of TrkA (NTRK1) expression from the 651 datasets of brain tumors. RNA sequence analysis identified overexpression of NTRK1 in GBM, recurrent GBM as well in Oligoastrocytoma patients. Also, TrkA expression tends to increase over the higher grades of GBM. TrkA protein targeting hydrazone derivatives, R48, R142, and R234, were designed and their mode of interaction was studied using molecular docking and dynamic simulation studies. Ligands' stability and binding assessment reveals R48, 2 2-(2-(2-hydroxy-4-nitrophenyl) hydrazineylidene)-1-phenylbutane-1,3-dione, as a potent ligand that interacts well with TrkA's hydrophobic residues, Ile, Phe, Leu, Ala, and Val. R48- TrkA exhibits stable binding potentials with an average RMSD value <0.8 nm. R48 obeyed Lipinski's rule of five and possessed the best oral bioavailability, suggesting R48 as a potential compound with drug-likeness properties. In-vitro analysis also revealed that R48 exhibited a higher cytotoxicity effect for U87 GBM cells than TMZ with the IC50 value of 68.99 μM. It showed the lowest percentage of cytotoxicity to the non-cancerous TrkA expressing MEF cells. However, further SiRNA analysis validates the non-specific binding of R48, necessitating structural alteration for the development of R48-based TrkA inhibitor for GBM therapeutics.

CNSC-35. EVALUATING THE THERAPEUTIC POTENTIAL OF NOVEL NTRK AGONISTS AND ANTAGONISTS IN HIGH-RISK NEUROBLASTOMA

Abstract Neuroblastoma is the most common extra-cranial tumor diagnosed in children within the first two years of their lives. Although low-risk and intermediate -risk neuroblastoma patients have a survival rate of 90-95%, high-risk neuroblastoma patients have a survival rate of approximately 50%. To improve the survival rate in high-risk patients, our group focuses on tropomyosin receptor kinases (TRKs), which are family of tyrosine kinases that have been heavily implicated in crucial developmental processes, such as differentiation, that are typically hijacked in cancer. Using de novo agonists specifically designed against three different neurotrophin receptors (TrkA, TrkB, TrkC), our group is investigating the fundamental biological role of TRK receptors in mediating tumorigenesis in neuroblastoma. Preliminary results show that our TrkA agonist not only increase both ERK and AKT activity but also causes a significant decrease in TrkA expression in several neuroblastoma cell lines which we hypothesize is due to constitutive activation of TrkA, leading to its internalization and degradation. Phenotypically, we observe that neuroblastoma cell line SK-N-SY5Y, which is typically used in differentiation studies, lose their neuroblast-like phenotype when treated with TrkA agonist, and begin to exhibit neurite outgrowth which may be indicative of differentiation-associated pathways being activated due to TrkA activation. Using a combination of de novo protein design, immunoblotting, RNA-sequencing, and in vivo studies to characterize the effect(s) TRK agonists have on neuroblastoma, we hope to assess whether targeting and modifying the activity of TrkA, and other Trk receptors such as TrkB and TrkC, holds new therapeutic promise for patients with high-risk neuroblastoma.

An in silico study of protein-protein interactions and design of novel peptides for TrkA in ameloblastoma

Ameloblastoma is a benign odontogenic jawbone tumor. The binding of Nerve growth factor (NGF) to receptor tyrosine kinase A (TrkA) promotes cell survival, proliferation, and differentiation via PI3K/AKT and Ras/MAPK signaling. Although the exact cause of ameloblastoma remains unknown, elevated levels of NGF and TrkA expression in ameloblastoma are associated with aggressive tumor behavior and poor patient outcomes. It is previously demonstrated that His 4, Arg 9, and Glu 11 residues of NGF made crucial interactions with the TrkA subunit. The main aim of our present study to develop potential therapeutic strategies by identifying promising peptide candidates. The objectives include starting with a detailed in silico analysis to identify a crucial peptide sequence of NGF that is bound by TrkA, creating a library of novel peptides from the identified peptide sequence through a single-point mutation on interacting residues (His 4, Arg 9, and Glu 11), and selecting the top peptides based on docking score, interactions analysis, and desirable pose analysis. The study ultimately designed a hybrid peptide candidate through the simultaneous and continuous mutation of the top residues, resulting in a peptide that exhibited a more specific interaction with TrkA, blocking the binding site and preventing the interaction between NGF and TrkA. Communicated by Ramaswamy H. Sarma

NGF/PI3K/TRPV1 pathway mediates the regulation of visceral pain by acupuncture at "Shangjuxu" (ST37) in irritable bowel syndrome rats with chronic visceral hyperalgesia.

To investigate the effect of manual acupuncture at "Shangjuxu"(ST37) on nerve growth factor(NGF)/phosphatidylinositol 3-kinase(PI3K)/transient receptor potential vanilloid 1(TRPV1) signaling pathway in rats with chronic visceral hyperalgesia of irritable bowel syndrome (IBS), so as to explore its underlying mechanism in treating IBS chronic visceral hyperalgesia. IBS chronic visceral hyperalgesia model was established by colorectal dilation stimulation for 2 weeks for SD pups at 8 d after birth, which were fed until 8-week age after the stimulation. Then the verified successfully modeled adult rats were randomly divided into model, Shangjuxu, and non-acupoint groups, with 6 rats in each group, and 6 unmodeled rats were selected as normal group. On the next day of model evaluation, rats in the Shangjuxu group received acupuncture at right ST37 while rats in the non-acupoint group received acupuncture at the non-meridian and non-acupoint point in the right hypochondrium, both for 15 min, with manual twisting of mild reinforcing and reducing performed for 30 s at an interval of 5 min, once a day, for a total of 7 d. Abdominal withdrawal reflex(AWR) score was used to evaluate the degree of chronic visceral pain in rats. Western blot and real-time fluorescence quantitative PCR were used to detect the colonic protein and mRNA expressions of NGF, tropomyosin receptor kinase A (TrkA), PI3K and TRPV1. The positive expressions of PI3K and TRPV1 proteins in the colon of rats were detected by immunohistochemistry method. Compared with the normal group, AWR scores corresponding to 4 pressure levels of 20, 40, 60 and 80 mm Hg, mRNA and protein expressions of NGF, TrkA, PI3K and TRPV1 in colon tissue, and positive expressions of PI3K and TRPV1 in colon tissue were significantly increased(P<0.05) in the model group. After intervention, compared with the model group, rats in the Shangjuxu group had reduced AWR scores corresponding to 4 pressure levels of 20, 40, 60 and 80 mm Hg, lower colonic mRNA and protein expressions of NGF, TrkA, PI3K and TRPV1, and decreased positive expressions of PI3K and TRPV1 in colon tissue(P<0.05), while there were no significant differences in the above indexes of the non-acupoint group. Manual acupuncture at ST37 can alleviate IBS chronic visceral hyperalgesia in rat and its analgesic effect may be related to regulating NGF/PI3K/TRPV1 signaling pathway.

Induction of Cholinergic Phenotype in Mouse Neuroblastoma Cells Using Nerve Growth Factor

Nerve growth factor (NGF) is a key factor of neuronal differentiation. NGF plays an important role in growth and differentiation of sensory and sympathetic neurons in the peripheral nervous system. In the mature brain, NGF is important for the maintenance of a cholinergic neuronal phenotype. Here, we studied whether NGF is sufficient to induce cholinergic phenotype in murine neuroblastoma cells, which are often used to model various physiological and pathological conditions. We detected expression of both TrkA and p75NGFR of NGF receptors in NB41A3 and Neuro2a neuroblastoma cells, two the most popular cell lines widely used to study the properties of cholinergic neurons in vitro. Treatment of both types of cell cultures with NGF did not induce in contrast to 8-Br-cAMP, which induced differentiation of Neuro2a cells with formation neuron-like morphology. Furthermore, we did not reveal the markers of cholinergic phenotype, such as ChAT or VAChT mRNA or protein in these cells, after NGF treatment. Thus, NB41A3 and Neuro2a cells cannot be used as an in vitro model of cholinergic cells because they do not differentiate and/or exhibit cholinergic phenotype in response to NGF stimulation.

Enhanced TrkA signaling impairs basal forebrain-dependent behavior.

Basal forebrain cholinergic neurons (BFCNs) modulate cognitive functions such as attention, learning and memory. The NGF/TrkA pathway plays an important role in the development and function of BFCNs, although two mouse models conditionally deleting TrkA expression in the central nervous system (CNS) have shown contradictory results. To shed light into this discrepancy, we used a mouse model with a gain-of-function in TrkA receptor signaling. Our results indicate that enhanced TrkA signaling did not alter hippocampal cholinergic innervation, general locomotion or anxiety-related behaviors, but it increases ChAT expression, the number of cholinergic neurons at early postnatal stages and, mutant mice showed impaired motor learning and memory functions. These data demonstrate that proper functioning of the cholinergic system in CNS requires a balanced NGF/TrkA signaling.