TrkC signaling is activated in adenoid cystic carcinoma and requires NT-3 to stimulate invasive behavior

Abstract

Treatment options for adenoid cystic carcinoma (ACC) of the salivary gland, a slowly growing tumor with propensity for neuroinvasion and late recurrence, are limited to surgery and radiotherapy. Based on expression analysis performed on clinical specimens of salivary cancers, we identified in ACC expression of the neurotrophin-3 receptor TrkC/NTRK3, neural crest marker SOX10, and other neurologic genes. Here, we characterize TrkC as a novel ACC marker, which was highly expressed in 17 out of 18 ACC primary-tumor specimens, but not in mucoepidermoid salivary carcinomas or head and neck squamous cell carcinoma. Expression of the TrkC ligand NT-3 and Tyr-phosphorylation of TrkC detected in our study suggested the existence of an autocrine signaling loop in ACC with potential therapeutic significance. NT-3 stimulation of U2OS cells with ectopic TrkC expression triggered TrkC phosphorylation and resulted in Ras, Erk 1/2 and Akt activation, as well as VEGFR1 phosphorylation. Without NT-3, TrkC remained unphosphorylated, stimulated accumulation of phospho-p53 and had opposite effects on p-Akt and p-Erk 1/2. NT-3 promoted motility, migration, invasion, soft-agar colony growth and cytoskeleton restructuring in TrkC-expressing U2OS cells. Immunohistochemical analysis demonstrated that TrkC-positive ACC specimens also show high expression of Bcl2, a Trk target regulated via Erk 1/2, in agreement with activation of the TrkC pathway in real tumors. In normal salivary gland tissue, both TrkC and Bcl2 were expressed in myoepithelial cells, suggesting a principal role for this cell lineage in the ACC origin and progression. Sub-micromolar concentrations of a novel potent Trk inhibitor AZD7451 completely blocked TrkC activation and associated tumorigenic behaviors. Pre-clinical studies on ACC tumors engrafted in mice showed efficacy and low toxicity of AZD7451, validating our in vitro data and stimulating more research into its clinical application. In summary, we describe in ACC a previously unrecognized pro-survival neurotrophin signaling pathway and link it with cancer progression.

Adenoid cystic carcinoma of the head and neck – An update

“…In this context, the overexpression of a cluster of neuronal genes grouped around TrkC/NTRK3 (a tyrosine kinase neurotrophic receptor associated with neurogenesis and cancer) suggests that AdCC expresses genes involved in neural stem cell differentiation [60].…”

Investigation of neurotrophic tyrosine kinase receptor 1 fusions and neurotrophic tyrosine kinase receptor family expression in non-small-cell lung cancer and sensitivity to AZD7451 in vitro

“…For this reason, we further investigated the in vitro antitumor effects of AZD7451 on the KM12 cell line [colorectal cancer cell line harboring tropomyosin (TPM)-NTRK1 fusion] (6) and the H460 and H810 cell lines (LCNEC cell lines exhibiting NTRK2 expression). AZD7451 is a potent small-molecule pan-TRK inhibitor with a high degree of specificity and selectivity as compared to other kinases (9). We also performed a PCR using total mRNA extracted from the three cell lines and examined the total mRNA expression levels in these cell lines.…”

Adenoid Cystic Carcinoma

“…Recently, Ivanov and associates identifi ed the expression of the neurotrophin-3 receptor TrkC/NTRK3 in ADCCs suggesting a hitherto unrecognised pro-survival neurotrophin signalling pathway linked with cancer progression. The TrkC signalling requires NT-3 to stimulate invasive behaviour and may hence have a future clinical application [ 87 ]. Adenoid cystic carcinoma is a slowly growing tumour and has a dismal long -term prognosis, and at least the 15-year and preferably the 20-year survival rate should be taken into account.…”