Inhibition of Uterine Sarcoma Cell Growth through Suppression of Endogenous Tyrosine Kinase B Signaling

Abstract

Uterine leiomyosarcoma is an aggressive tumor typically found at advanced stages due to difficulties with early diagnosis. Because uterine leiomyosarcoma is resistant to conventional radiation and chemotherapy, the development of more potent medical therapeutics is anticipated. Using quantitative real-time RT-PCR and immunostaining, we found the expression of brain-derived neurotrophic factor (BDNF) and neurotropin-4/5, together with their receptor, tyrosine kinase B (TrkB), in different uterine sarcoma cell lines and primary tumor samples from uterine leiomyosarcoma patients. We noted that levels of BDNF were more abundant than those of neurotropin-4/5. Moreover, the expression of TrkB and its ligands was elevated in a multidrug-resistant cell line and samples obtained from patients with leiomyosarcoma. In cultured uterine sarcoma cells, inhibition of endogenous TrkB signaling by treatment with either the soluble TrkB ectodomain or the Trk receptor inhibitor, K252a, suppressed cell proliferation and increased apoptosis based on cell viability and proliferation, in situ terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick end-labeling and caspase-3/7 assays, whereas an inactive plasma membrane nonpermeable K252b was ineffective. Correspondingly, treatment with exogenous BDNF increased cell proliferation. In in vivo studies in athymic nude mice bearing multidrug-resistant uterine sarcoma cell tumors, we demonstrate suppression of tumor growth by treatment with K252a, but not K252b, as reflected by decreased cell proliferation and increased levels of apoptosis and caspase-3/7 activities without obvious side effects. Our findings indicated that endogenous signaling of the TrkB pathway contributed to uterine sarcoma cell growth, and inhibition of TrkB signaling in these tumors could provide a novel medical therapy for patients with uterine sarcomas.

Upregulation of TrkB Promotes Epithelial-Mesenchymal Transition and Anoikis Resistance in Endometrial Carcinoma

“…Previous studies have demonstrated a key role for BDNF-TrkB signaling in modulating the response to cytotoxic agents, and modulation of TrkB expression enhanced the sensitivity of cells to cis-Diamminedichloroplatinum Cisplatin (CDDP) in head and neck squamous cell carcinoma [16]. Recently, It was reported Trk inhibitor K252a inhibited cell growth and induced apoptotic cell death in uterine leiomyosarcoma [47].Therefore, further studies are needed to explore the development of small-molecule compounds that act as TrkB antagonists, or monoclonal antibodies against either BDNF or TrkB, as promising novel therapies for the treatment of endometrial carcinoma. Our findings provide new insights into biological mechanisms of EC and establish TrkB as a potential target for future therapies for this disease.…”

BDNF: An Oncogene or Tumor Suppressor?

“…Mice inoculated with breast cancer cells and treated with antibodies against BDNF display slower tumor progression compared to mice treated with control antibodies (38). These results were recapitulated in a mouse model of uterine sarcoma (39) and neuroblastoma (40,41). Mice flanked with choriocarcinoma xenografts and subsequently treated with K252a exhibited drastically slower tumor growth paralleled with a tumor-specific 15-fold increase in caspase-3/7 levels (42).…”

NT3-chitosan elicits robust endogenous neurogenesis to enable functional recovery after spinal cord injury

“…injection of 6% chloral hydrate (0.6 mL/kg body weight), to prepare rat models of thoracic spinal cord transection (SI Materials and Methods). The amounts of k-252a and k-252b used in these experiments were based on previously published studies (26).…”