TrkA Expression Research Articles

Role of TrkA signaling during tadpole tail regeneration and early embryonic development in Xenopus laevis.

Neurotrophic signaling regulates neural cell behaviors in development and physiology, although its role in regeneration has not been fully investigated. Here, we examined the role of neurotrophic signaling in Xenopus laevis tadpole tail regeneration. After the tadpole tails were amputated, the expression of neurotrophin ligand family genes, especially ngf and bdnf, was up-regulated as regeneration proceeded. Moreover, notochordal expression of the NGF receptor gene TrkA, but not that of other neurotrophin receptor genes TrkB and TrkC, became prominent in the regeneration bud, a structure arising from the tail stump after tail amputation. The regenerated tail length was significantly shortened by the pan-Trk inhibitor K252a or the TrkA inhibitor GW-441756, but not by the TrkB inhibitor ANA-12, suggesting that TrkA signaling is involved in elongation of regenerating tails. Furthermore, during Xenopus laevis embryonic development, TrkA expression was detected in the dorsal mesoderm at the gastrula stage and in the notochord at the neurula stage, and its knockdown led to gastrulation defects with subsequent shortening of the body axis length. These results suggest that Xenopus laevis TrkA signaling, which can act in the mesoderm/notochord, plays a key role in body axis elongation during embryogenesis as well as tail elongation during tadpole regeneration.

Nerve growth factor (NGF)-TrkA axis in head and neck squamous cell carcinoma triggers EMT and confers resistance to the EGFR inhibitor erlotinib.

Understanding the molecular mechanisms regulating tumor dissemination and therapeutic resistance is of central importance for effective cancer therapies. Here, we report that nerve growth factor (NGF) and its receptor TrkA facilitate epithelial-mesenchymal transition (EMT) and EGFR inhibitor resistance via STAT3 activation in head and neck squamous cell carcinoma (HNSCC). Both NGF and TrkA expression were elevated in HNSCC, indicating poor clinical outcomes. NGF was highly expressed in cancer cells and nerves in perineural niche, whereas TrkA expression was higher in cancer cells with perineural invasion. The NGF/TrkA axis could promote HNSCC cell dissemination and trigger EMT via STAT3 activation. Moreover, we discovered that the NGF/TrkA axis conferred resistance to the EGFR inhibitor erlotinib via EMT processes in HNSCC cells. Blocking TrkA signaling markedly reversed EMT and sensitized HNSCC cells to erlotinib in both in vitro and in vivo models. Overall, our results demonstrate novel evidence that the paracrine NGF/TrkA axis favors EMT and confers EGFR-targeted therapeutic resistance in HNSCC.

Nerve growth factor and Tropomyosin receptor kinase A are increased in the gastric mucosa of patients with functional dyspepsia

BackgroundNerve growth factor (NGF) and enteric glial cells (EGCs) are associated with visceral hypersensitivity and gastrointestinal motility disorder, which may represent the pathogenesis of functional dyspepsia (FD). This study aimed to investigate the expression of NGF, its high affinity receptor tropomyosin receptor kinase A (TrkA) and the EGC activation marker glial fibrillary acidic protein (GFAP) in the gastric mucosa of patients with FD and the association of these proteins with dyspeptic symptoms.MethodsGastric mucosal biopsies taken from 27 FD patients (9 epigastric pain syndrome (EPS) patients, 7 postprandial distress syndrome (PDS) patients and 11 EPS overlap PDS patients) and 26 control subjects were used for analysis. The expression of NGF, TrkA and GFAP was examined, and the association of these proteins with dyspeptic symptoms, including epigastric pain, postprandial fullness, early satiation and epigastric burning, was analysed.ResultsThe expression levels of NGF, TrkA, and GFAP in the gastric mucosa were significantly higher in the EPS group, the PDS group, and the EPS overlap PDS group than in the healthy control group. There was no significant difference between the FD subgroups. TrkA colocalized with GFAP, which indicated that TrkA was localized to EGCs, and the expression of TrkA in EGCs was significantly higher in the FD group than in the control group. Changes in the expression of NGF, TrkA, and GFAP were positively correlated with epigastric pain, postprandial fullness and early satiation but had no significant relationship with epigastric burning.ConclusionsThe increased expression of gastric NGF, TrkA and GFAP might be involved in FD pathophysiology and symptom perception.

Expression of Nerve Growth Factor and Tyrosine Kinase A in Laryngeal Squamous Cell Carcinoma: A Novel Study

AbstractBackground: Laryngeal Squamous Cell Carcinoma (LS-CC) is a common cancer worldwide so knowing the biological markers related to this tumor aggressiveness can help improv-ing the patient's management. A recent attention was payed towards Nerve Growth Factor (NGF) and its receptors in tumorigenesis.Aim of Study: This work aimed at studying for the first time the immunohistochemical expression of NGF and its TrkA receptor in LSCC and determine the possibility of finding a relationship between their expression and the different clinico-pathological data of the patients especially the clinical stage of the disease.Material and Methods: Using the immunohistochemical staining, the expression of NGF and TrkA was evaluated in 60 LSCC tissues.Results: The result showed that the expression of both NGF and TrkA was significantly related to the nodal status, the tumor and the clinical stages of the patients (p<0.001).Conclusion: The increased expression of both markers in advanced clinical stage of the disease suggested considering them as potential markers not only as prognostic factors, but also as a therapeutic target in LSCC.

Up-regulated GGA3 promotes non-small cell lung cancer proliferation by regulating TrkA receptor

Background: GGA3 has been reported to be related to cellular events such as cell survival, cell migration and cell apoptosis through different molecular mechanisms, which imply the potential role in tumorigenesis. However, the function of GGA3 in non-small cell lung cancer (NSCLC) is not clear. This research aims to reveal the effect of GGA3 on NSCLC proliferation and its underlying mechanisms. Methods: The mRNA expression of GGA3 and TrkA, and association between GGA3 and TrkA in NSCLC tissues were analyzed based on data from TCGA database. And the mRNA expression level of GGA3 in NSCLC cell lines was determined by qRT-PCR. Expression level of GGA3 in A549 cell was detected by qRT-PCR and western blot after transfected with pcDNA3.1-GGA3. Cell counting kit 8, transwell, and flow cytometry assays were performed to detect A549 cell proliferation, aggressiveness, and apoptosis. Western blot was applied to assess the protein expression during apoptosis and TrkA-AKT/ERK signaling pathway. Results: High expression of GGA3 was presented in NSCLC tissues and cell lines. In addition, overexpression of GGA3 could promote proliferation, invasion, and migration of A549 cell, but inhibit the apoptosis of A549 cell. After depletion of GGA3, the expression of anti-apoptotic protein Bcl-2 was increased, and the expression of pro-apoptotic protein Bax and Active Caspase 3 were reduced. Moreover, we found the expression of TrkA, p-AKT and p-ERK in pcDNA3.1-GGA3 group were obviously up-regulated in contrast with the sham group, which suggested that the induced effect of GGA3 on NSCLC cells might be performed via the TrkA-AKT/ERK signaling pathway. Conclusions: Taken together, overexpressed GGA3 in NSCLC could promote the A549 cells tumorigenesis partly through TrkA-AKT/ERK signaling pathway, supplying a theoretical basis for revealing the mechanism for NSCLC.

Up-regulated GGA3 promotes non-small cell lung cancer proliferation by regulating TrkA receptor.

BackgroundGGA3 has been reported to be related to cellular events such as cell survival, cell migration and cell apoptosis through different molecular mechanisms, which imply the potential role in tumorigenesis. However, the function of GGA3 in non-small cell lung cancer (NSCLC) is not clear. This research aims to reveal the effect of GGA3 on NSCLC proliferation and its underlying mechanisms.MethodsThe mRNA expression of GGA3 and TrkA, and association between GGA3 and TrkA in NSCLC tissues were analyzed based on data from TCGA database. And the mRNA expression level of GGA3 in NSCLC cell lines was determined by qRT-PCR. Expression level of GGA3 in A549 cell was detected by qRT-PCR and western blot after transfected with pcDNA3.1-GGA3. Cell counting kit 8, transwell, and flow cytometry assays were performed to detect A549 cell proliferation, aggressiveness, and apoptosis. Western blot was applied to assess the protein expression during apoptosis and TrkA-AKT/ERK signaling pathway.ResultsHigh expression of GGA3 was presented in NSCLC tissues and cell lines. In addition, overexpression of GGA3 could promote proliferation, invasion, and migration of A549 cell, but inhibit the apoptosis of A549 cell. After depletion of GGA3, the expression of anti-apoptotic protein Bcl-2 was increased, and the expression of pro-apoptotic protein Bax and Active Caspase 3 were reduced. Moreover, we found the expression of TrkA, p-AKT and p-ERK in pcDNA3.1-GGA3 group were obviously up-regulated in contrast with the sham group, which suggested that the induced effect of GGA3 on NSCLC cells might be performed via the TrkA-AKT/ERK signaling pathway.ConclusionsTaken together, overexpressed GGA3 in NSCLC could promote the A549 cells tumorigenesis partly through TrkA-AKT/ERK signaling pathway, supplying a theoretical basis for revealing the mechanism for NSCLC.

Results of a first panTRK IHC ringtrial

Abstract Background Because of the limited experience with tyrosine kinase receptor (TRK) gene fusion, a Belgian ring trial for TRK immunohistochemistry (IHC) staining was organised by the pathology department of Antwerp University Hospital. The trial was conducted between January and July 2019 with a total of 9 participating laboratories and aimed to harmonize pan-TRK IHC staining protocols and pan-TRK IHC interpretation. Methods The first and last slides of six selected cases were stained for TRK using the VENTANA pan-TRK Assay (clone EPR17341) on the Benchmark Ultra platform. Each participating laboratory received two unstained slides and was asked to return one TRK–stained slide per case and to report the protocol used and their interpretation. One site participated with two different protocols. The stained slides were evaluated by two designated pathologists. The results of a comparative study evaluating the IHC interpretations from the in-house pathologists of the different laboratories and those obtained from the trial-designated pathologists were communicated to the participating laboratories. Results Two different clones were used during the ring trial: A7H6R (Cell Signaling) and EPR17341 (Abcam/Ventana). The VENTANA pan-TRK Assay (clone EPR17341) on the Benchmark Ultra platform was most popular and used by 40% of the labs. The remaining in-house protocols used EPR17341 in its concentrated form (abcam) or A7H6R (Cell Signaling). Overall, 7 protocols achieved a sufficient performance mark and 3 labs were advised to further optimise the protocol. Interpretation of panTRK IHC proofed to be challenging in cases with physiological TRK expression. In addition, depending on the NTRK fusion partner, the staining can vary strongly in both intensity and staining pattern. Conclusions To our knowledge, this is the first panTRK IHC ring trial. According to our results, the EPR17341 and A7H6R clones are both highly recommendable antibodies for panTRK IHC. Labs using the Ventana ready-to-use system based on the EPR17341 clone and using the recommended protocol settings scored best. However, given some small optimisation, all labs scored well on the technical staining and the succeeding evaluation. Legal entity responsible for the study Antwerp University Hospital. Funding Bayer. Disclosure All authors have declared no conflicts of interest.

β-Hydroxybutyrate Ameliorates Aβ-Induced Downregulation of TrkA Expression by Inhibiting HDAC1/3 in SH-SY5Y Cells.

Tyrosine kinase receptor A (TrkA) plays an important role in the protection of cholinergic neurons in Alzheimer's disease (AD). This study was designed to investigate whether β-hydroxybutyrate (BHB), an endogenous histone deacetylase (HDAC) inhibitor, upregulates the expression of TrkA by affecting histone acetylation in SH-SY5Y cells treated with amyloid β-protein (Aβ). The results showed that BHB ameliorated the reduction of cell vitality and downregulation of TrkA expression induced by Aβ. Furthermore, BHB inhibited the upregulation of HDAC1/2/3 expression and downregulation of histone acetylation (Ace-H3K9 and Ace-H4K12) levels in Aβ-treated cells. The expression of TrkA was upregulated in HDAC1- or 3-silenced SH-SY5Y cells. However, there was no significant difference in TrkA expression between the HDAC2 knockdown and control cells. In conclusion, this study demonstrates that BHB protects against Aβ-induced neurotoxicity in SH-SY5Y cells. The underlying mechanism of the effect may be associated with the upregulation of TrkA expression by inhibiting HDAC1/3.

Effect and mechanisms of sacral nerve stimulation on visceral hypersensitivity mediated by nerve growth factor.

To investigate the efficacy of sacral nerve stimulation (SNS) on nerve growth factor (NGF) mediated visceral sensitivity in normal rat and visceral hypersensitivity model rats. 120 male newborn rats were randomly divided into 6 groups: group A was normal model group; group B ~ F were all sensitized with acetic acid enema and grouped again. Group c2 was given NGF antagonist, d2 group was given NGF agonist, e2 group was given PI3K inhibitor, and f2 group was given PLC‐γ inhibitor. After treatment, the expression of NGF, TrKA, PI3K, AKT, PLC‐γ, NF‐κB, TRPV1, pTRPV1 and intracellular Ca2+ content were detected. The expression of protein TRPV1 and pTRPV1 was increased, and Ca2+ was increased in the visceral hypersensitive group. NGF, TrKA in NGF antagonist group, PI3K, AKT, NF‐κB in PI3K inhibitor group, PLC‐γ in PLC‐γ inhibitor group were all almost not expressed. The relative expression of NGF, TrKA, PI3K, AKT, PLC‐γ and NF‐κB in NGF antagonist group was lower than that in visceral hypersensitivity group and NGF activator group (P < .01). The relative expression of NGF, TrKA, PI3K and AKT mRNA in NGF antagonist group was lower than that in the normal model group (P < .01). There was no significant difference in the relative expression of PLC‐γ and NF‐κB mRNA (P > .05). The expression level of MAPK, ERK1 and ERK2 in visceral hypersensitivity group was higher than that in PI3K inhibitor group and PLC‐γ inhibitor group. The normal group Ca2+ curve was flat, and the NGF agonist group had the highest Ca2+ curve peak. Calcium concentration in visceral hypersensitivity group was higher than that in PI3K inhibitor group and that in PLC‐γ inhibitor group was higher than that in NGF antagonist group. The binding of TrkA receptor to NGF activates the MAPK/ERK pathway, the PI3K/Akt pathway and the PLC‐γ pathway, causing changes in the fluidity of intracellular and extracellular Ca2+, resulting in increased sensitivity of visceral tissues and organs.

Two Receptors, Two Isoforms, Two Cancers: Comprehensive Analysis of KIT and TrkA Expression in Neuroblastoma and Acute Myeloid Leukemia.

Pediatric cancers represent a wide variety of different tumors, though they have unique features that distinguish them from adult cancers. Receptor tyrosine kinases KIT and TrkA functions in AML and NB, respectively, are well-characterized. Though expression of these receptors is found in both tumors, little is known about KIT function in NB and TrkA in AML. By combining gene enrichment analysis with multidimensional scaling we showed that pediatric AMLs with t(8;21) or inv16 and high KIT expression levels stand out from other AML subtypes as they share prominent transcriptomic features exclusively with KIT-overexpressing NBs. We showed that AML cell lines had a predominant expression of an alternative TrkAIII isoform, which reportedly has oncogenic features, while NB cell lines had dominating TrkAI-II isoforms. NB cells, on the other hand, had an abnormal ratio of KIT isoforms as opposed to AML cells. Both SCF and NGF exerted protective action against doxorubicin and cytarabine for t(8;21) AML and NB cells. We identified several gene sets both unique and common for pediatric AML and NB, and this expression is associated with KIT or TrkA levels. NMU, DUSP4, RET, SUSD5, NOS1, and GABRA5 genes are differentially expressed in NBs with high KIT expression and are associated with poor survival in NB. We identified HOXA10, BAG3, and MARCKS genes that are connected with TrkA expression and are marker genes of poor outcome in AML. We also report that SLC18A2, PLXNC1, and MRPL33 gene expression is associated with TrkA or KIT expression levels in both AML and NB, and these genes have a prognostic value for both cancers. Thus, we have provided a comprehensive characterization of TrkA and KIT expression along with the oncogenic signatures of these genes across two pediatric tumors.

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.

654 Stimulation and Protection of Cutaneous Sensory Neuron System induced by Forest Honey from Ikaria Island

Sensory innervation involves nerve endings which are located in dermis and epidermis, reaching the uppermost viable layer of skin. Cutaneous innervation is closely linked with major skin functions and contributes to skin homeostasis. Wound-healing, repair process, sense of touch, perception of thermal stimuli as well as intra-epidermal nerve fibre density on face decrease with aging and are associated with changes in neuronal functions and structures. For centuries, honey has been utilized for wound healing purposes but recently, information regarding honey’s mechanisms of action on wound healing and as a therapeutic agent for skin disorders has accumulated at a rapid pace. However, each honey is very specific especially due to the surrounding flora and bee strains associated. Our previous studies have shown that all honeys were not equivalent and consequently, they did not induce the same biological activities. For counteracting the alteration of sensory innervation system, we studied the activities of a forest honey from Ikaria Island (FHII) on a new human sensory neurons 2D model. Human sensory neurons derived from human induced pluripotent cells were co-cultured with human keratinocytes. After treatment by FHII for 10 days; the numbers of neurons, the growth of neurites and the expression of TrkA (NGF receptor) and mu-opioid receptors (MOR), which are four key parameters for sensory neuron homeostasis, were studied by immunocytofluorescence. We have observed that treatment by FHII did not induce neurone proliferation but significantly stimulated by 30% the growth of neurites and the increase of TrkA and MOR expressions by +38% and +45% respectively. These results indicate that FHII stimulates the development of neuronal network, protects its functionalities and suggest a beta-endorphin-like activity of this natural compound making this forest honey from Ikaria island a good candidate for maintaining homeostasis of human cutaneous sensory neuron system and skin.

454 Occurrence of TRKAIII splice variant in melanoma: a pilot study

TrkA is a member of the transmembrane neurotrophin receptor family with a critical role in cell proliferation, survival and differentiation. TrkA oncogenic activation is an emerging driver in a wide variety of solid tumors, and TrkA-targeted therapies using inhibitors have been reported to exhibit marked and durable efficacy. An alternative TrkA splice variant, the TrkAIII, characterized by exon 6-7 skipping, exhibits spontaneous aberrant activation. We aimed to explore a potential oncogenic role for TrkA in cutaneous melanoma. Cutaneous melanoma samples from patients of stage III-IV have been collected from the Department of Dermatology of University of L’Aquila. DNA and RNA was extracted from FFPE sections. The cDNA was amplified using TrkA-specific primers. The copy number variation of TrkA gene was evaluated by TaqMan Copy Number assays. Somatic mutations in the region spanning TrkA intron/exon 6 to the intron/exon 8 were analyzed by Sanger Sequencing. Overall, we collected 30 primary melanomas tissue and 12 normal skin specimens. We identified predominant alternative TrkAIII splice variant in 16 of 30 (53%) primary melanomas, while the remaining 14 (47%) cases express mainly the full length TrkA. Normal skin samples exhibit low to undetectable full length TrkA expression. The presence of TrkAIII was always confirmed by sequencing. Somatic DNA mutations in intron/exon boundary that could explain the exons skipping were not found. TrkA gene amplification was detected in 4 of 30 (13%) melanomas. Our results could open the way to new personalized therapeutic approaches for melanoma patients by targeting TrkA oncogenic signals.

Effects of the selective TrkA agonist gambogic amide on pigmentation and growth of human hair follicles in vitro.

The human hair follicle is a neuroendocrine mini-organ that can be used to study aging processes in vitro. Neurotrophins maintain homeostasis in hair biology via the Trk-family of receptors. TrkA, the high affinity receptor for nerve growth factor (NGF), is expressed in hair follicle melanocytes and keratinocytes, where it regulates proliferation, differentiation and apoptosis and may thereby play a role in hair pigmentation and growth. We investigated TrkA expression during the human hair cycle and the effects of a selective high affinity TrkA agonist, Gambogic Amide, on hair pigmentation and hair growth in human hair follicles in vitro. In human scalp skin, TrkA expression was strongest in proliferating melanocytes re-establishing the pigmentary unit in the hair bulb during the early hair growth phase, anagen. During high anagen and in the de-composing pigmentary-unit of the regression phase, catagen, bulb-melanocytes lost TrkA expression and only undifferentiated outer root sheath melanocytes maintained it. In cultured human anagen hair follicles, Gambogic Amide was able to prevent gradual pigment loss, while it stimulated hair shaft elongation. This was achieved by increased melanocyte activation, migration and dendricity, highlighted by distinct c-KIT-expression in melanocyte sub-populations. Our results suggest that Gambogic Amide can maintain hair follicle pigmentation by acting on undifferentiated melanocytes residing in the outer root sheath and making them migrate to establish the pigmentary-unit. This suggests that the selective TrkA agonist Gambogic Amide acts as an anti-hair greying and hair growth promoting molecule in vitro.

TrkA neurotrophin receptor and PI3K-Akt signaling involvement in cranial irradiation-induced memory deficit.

e14679 Background: This study aimed to investigate the role of neurotrophin receptor TrkA in cranial radiation-induced memory decline. Methods: Single dose of 10Gy 4MeV electron beam whole brain irradiation (WBI) was given to young male Sprague-Dawley rats (50–60g, day 21). 3 months after WBI, western blot was performed to detect protein level of TrkA and its downstream signaling molecules. The Morris water maze test was performed to evaluate the consequence of WBI on hippocampus-dependent memory formation. Immunohistochemistry was performed to evaluate the consequence of WBI on neurogenesis. For overexpression of TrkA, Adeno-associated virus were injected at the rate of 0.2μl/min (n = 15-20 per group). After that, Morris water maze test was performed again. Results: In Morris water maze test, WBI lead to notable memory deficit, the irradiation rats spent longer latency time than control rats (p &lt; 0.05). In the spatial probe trial, the irradiation rats spent less time in the target quadrant than control rats (p &lt; 0.05). Immunohistochemistry showed that cranial irradiation inhibited proliferation and neurogenesis in hippocampus. The protein level of TrkA expression decreased significantly at 3 months after irradiation compared with control group. Phosphorylation of PI3k, AKT, ERK1/2, CREB were also observed to be significantly inhibited (all p &lt; 0.05). Next, we explored the irradiation-induced apoptotic signal transduction. The increased expression of JNK, caspase-3/9 and reduced expression of BCl2 confirm the irradiation induced apoptosis. After Adeno-associated virus injection, AAV-overexpression TrkA rats showed less escape latency time (p &lt; 0.05) and spent more time (p &lt; 0.05) in the target quadrant than AAV-irradiation rats, but still more escape latency time (p &lt; 0.05) and spent less time (p &lt; 0.05) in the target quadrant than AAV-control rats. Additionally, immunofluorescence staining showed AAV-overexpression-TrkA also rescued radiation-induced neurogenesis impairment Conclusions: TrkA may play a critical role in radiation-induced memory deficit, which indicate the data may have important therapeutic implications.

Immunohistochemistry with a pan-TRK antibody distinguishes secretory carcinoma of the salivary gland from acinic cell carcinoma.

Secretory carcinoma (previously known as mammary analogue secretory carcinoma) is characterised by ETV6 rearrangements, most often ETV6-NTRK3 fusion. Given its histological overlap with other salivary gland tumours, secretory carcinoma can be difficult to diagnose without genetic confirmation. A recently developed pan-TRK antibody shows promise for identifying tumours with NTRK fusions. The aim of this study was to evaluate the utility of pan-TRK immunohistochemistry in distinguishing secretory carcinoma from mimics. We examined whole-tissue sections from 86 tumours, including 14 secretory carcinomas (12 parotid primaries and one buccal primary, and one metastasis; five with ETV6 rearrangement confirmed by fluorescence in-situ hybridisation, and one with ETV6-NTRK3 fusion and one with ETV6-RET fusion detected by targeted sequencing), 14 acinic cell carcinomas, 18 polymorphous adenocarcinomas, 20 low-grade mucoepidermoid carcinomas, and 20 pleomorphic adenomas. Immunohistochemistry was performed with a pan-TRK rabbit monoclonal antibody. Pan-TRK staining was detected in nine (64%) secretory carcinomas, all with a nuclear pattern and four with diffuse staining (>50% of cells). Among other tumour types, pan-TRK immunoreactivity was observed in all (100%) pleomorphic adenomas (particularly myoepithelial cell-rich, myxoid areas), 15 (83%) polymorphous adenocarcinomas, and four (20%) low-grade mucoepidermoid carcinomas, all with predominantly membranous/cytoplasmic immunoreactivity; only six cases showed focal (<10%) nuclear staining. All acinic cell carcinomas were entirely negative. Although pan-TRK expression is not entirely sensitive or specific for secretory carcinoma, nuclear staining distinguishes secretory carcinoma from mimics. Acinic cell carcinomas are negative for pan-TRK, though membranous expression of TRK is common in other salivary gland neoplasms. The lack of pan-TRK immunoreactivity in a subset of secretory carcinomas may suggest non-NTRK fusion partners.

Upregulation of TRPV1 in spinal dorsal root ganglion by activating NGF-TrkA pathway contributes to pelvic organ cross-sensitisation in rats with experimental autoimmune prostatitis.

Chronic prostatitis/chronic pelvic pain syndrome (CP⁄CPPS) is the prostate gland inflammation characterised as genitourinary pain in the pelvic region. The rat experimental autoimmune prostatitis (EAP) was achieved to mimic CP⁄CPPS. The expressions of transient receptor potential vanilloid 1 (TRPV1) in the prostate, bladder and spinal dorsal root ganglion (DRG) were analysed by Western blotting. Tropomyosin receptor kinase A (TrkA) and nerve growth factor (NGF) in the DRG were also analysed by Western blotting. Measurements of inflammatory cytokines were carried out according to the instructions of the corresponding kits. The expressions of TRPV1 in the prostate, bladder and DRG in the EAP group were significantly higher than those in the control group. The expressions of NGF and TrkA in the DRG in the EAP group were significantly higher than those in the control group. The levels of serum TNF-α and IL-1β in the EAP group were significantly higher than those in the control group. We conclude that CP⁄CPPS may participate in the pathological activation of neurons in the L5-S1 segment of DRG by activating NGF-TrkA pathway and cause pelvic organ cross-sensitisation by upregulating the expression of TRPV1 in the prostate, bladder and DRG.

Tropomyosin-Related Kinase Receptor and Neurotrophin Expression in Cutaneous Melanoma Is Associated with a Poor Prognosis and Decreased Survival

Objective: Normally, activation of tropomyosin-related kinase (TRK) receptors by neurotrophins (NTs) stimulates intracellular pathways involved in cell survival and proliferation. Dysregulation of NT/TRK signaling may affect neoplasm prognosis. Data on NT and TRK expression in melanomas are limited, and it is unclear whether NT/TRK signaling pathways are involved in the origin and progression of this neoplasm. Methods: We examined whether NT/TRK expression differs across different cutaneous melanoma grades and subtypes, and whether it is associated with melanoma prognosis and survival. A cross-sectional study was performed in which the expression of TrkA, TrkB, nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF) was analyzed by immunohistochemistry of 154 melanoma samples. We investigated NT/TRK expression associations with prognostic factors for melanoma, relapse-free survival (RFS), and overall survival (OS). Results: Of the 154 melanoma samples, 77 (55.4%) were TrkA immunopositive, 81 (58.3%) were TrkB immunopositive, 113 (81.3%) were BDNF immunopositive, and 104 (75.4%) were NGF immunopositive. We found NT/TRK expression associated strongly with several clinical prognostic factors, including the tumor-node-metastasis stage (p < 0.001), histological subtype (p < 0.001), and Clark level (p < 0.05), as well as with a worse OS (p < 0.05 for all, except TrkB) and RFS (p < 0.05 for all). Conclusions: Our results show strong associations of NT/TRK expression with melanoma stage progression and a poor prognosis.

Effect of Tamibarotene on the proliferation and Tyrosine kinase receptor A, N-myc expressions of neuroblastoma SH-SY5Y cells

Objective To study the effect of Tamibarotene on the SH-SY5Y cell proliferation inhibition ability and the mRNA and protein expressions of tyrosine kinase receptor a (TrkA) and N-myc (MYCN) in order to provide some experimental bases for the treatment of neuroblastoma. Methods The SH-SY5Y cells were treated with different concentrations of Am80 (0, 10, 20, 40, 80, 160 μmol/L) for 48 h, then Cell Counting Kit-8(CCK-8)was used to test the cell proliferation.Reverse transcription PCR(RT-PCR)and Western blot were used to test the mRNA and protein expressions of TrkA and MYCN at 48 hours. Results When the concentration was 10 μmol/L, Am80 had no significant inhibitory effect on SH-SY5Y cells[(3.51±1.68)%, inhibition ratio<5%]; but when the concentration was 20 μmol/L, it showed weak inhibition[(9.60±1.97)%, inhibition ratio<10%]. The inhibition rate of SH-SY5Y cell proliferation[(57.43±4.95)%] was significantly enhanced at Am80 with a concentration of 80 μmol/L.The concentrations of Am80 could effectively inhibit SH-SY5Y cell proliferation in a dose-dependent manner(P<0.05). The expression of TrkA increased with the increase of Am80 concentration.Am80 significantly decreased the expression of MYCN in SH-SY5Y cells(10 μmol/L: 0.65±0.05 vs.20 μmol/L: 0.36±0.06), and the difference was statistically significant(P<0.05). Conclusions It is suggested that Am80 can effectively inhibit SH-SY5Y cell proliferation in a concentration-dependent manner.The underlying mechanism involves increasing the expression of TrkA by down-regulation of MYCN. Key words: Tamibarotene; Neuroblastoma SH-SY5Y cells; Proliferation; Tyrosine kinase receptor A; N-myc gene

Predicting outcome of neuroblastoma using N-myc status and Trk-A expression

Background: Neuroblastoma is an embryonal cancer of the postganglionic sympathetic nervous system. It is the third most common pediatric cancer. The aim of the present study was to determine MYCN amplification and Trk-A expression in tissue samples of neuroblastoma cases and to correlate them with clinical status, stage and histopathology of the disease.Methods: This prospective study was conducted at the Institute of Child Health and hospital for children [ICH &amp; HC], Egmore during the period from June 2011 to March 2012. Ten children of age between 8 months to 12 years diagnosed with neuroblastoma were included in the study. Tissue samples were collected from all patients and sent to evaluate histopathology to confirm the presence of neuroblastoma. Gene expression was studied using TaqMan quantitative RT-PCR. Immunohistochemistry of tissues samples were done to evaluate N-myc amplification and Trk A expression.Results: The most common presenting symptom was mass in the abdomen (60%) in the patients. In majority, stage 3 neuroblastoma was noticed in 5 (50%) cases. On histopathology, 2 (20%) cases were identified of ganglioneuro-blastoma, and 8 (80%) cases as neuroblastoma. N-myc was amplified in 3 cases (30%). No amplification was noted in all 3 cases (0%) of stage 1. None of the case in this study group showed Trk-A expression.Conclusions: N-myc amplification was well correlated with the stages of neuroblastoma. It should be considered to be as an important prognostic marker to select appropriate treatment in children with neuroblastomas.