BDNF mediated TrkB activation is a survival signal for transitional cell carcinoma cells.
ABSTRACT Pathologically, >90% of bladder cancer is transitional cell carcinoma (TCC). Previously, brain-derived neurotrophic factor (BDNF) but not tropomyosin-related kinase B (TrkB) was found in normal urothelium. TrkB activation by BDNF has been shown to promote the progression of several cancers, however, the existence and functional roles of both BDNF and TrkB in TCC have not been elucidated. In this study, three human TCC cell lines, BFTC905, TSGH8301, and T24 were used for the investigation. Both BDNF and TrkB but not TrkA or TrkC identified by RT-PCR and Western blotting were found in these cell lines. Immunostaining demonstrated the cytosolic expression of BDNF and TrkB, as well as membranous expression of TrkB in these cells. BDNF released from three cell lines was also detected in culture medium by ELISA. The proliferation of BFTC905 cells was enhanced by recombinant human BDNF (rhBDNF) in vitro, which was associated with increased phospho-TrkB and phospho-ERK levels. In contrast, TrkB-Fc chimeric protein served as BDNF scavenger eliciting cytotoxicity. Addition of rhBDNF in these cell lines cultured in poly-HEMA [Poly(2-hydroxyethyl methacrylate)] coated dishes for 48 h did not confer resistance to anoikis. Increased phospho-Akt expression was observed transiently within an hour after rhBDNF administration but disappeared 24 h later. Weekly injections of 100 ng rhBDNF into the cancer cell-loading site for 6 weeks promoted BFTC905 xenograft growth in SCID mice. Daily injection of 5 microg TrkB-Fc chimeric protein into the tumor 2 weeks after tumor cell implantation delayed tumor growth concomitant with phospho-TrkB suppression in xenografts. These results indicate that BDNF binding to TrkB receptor is a survival signal for TCC cells. Drugs that block BDNF or TrkB may provide a new and potential approach for TCC therapy.
- SourceAvailable from: PubMed Central[show abstract] [hide abstract]
ABSTRACT: Brain-derived neurotrophic factor (BDNF) and its receptor Tropomysin-related kinase B (TrkB) are commonly up-regulated in a variety of human tumors. However, the roles of BDNF/TrkB in hepatocellular carcinoma (HCC) have been poorly investigated. We evaluated the expressions of BDNF and TrkB in 65 cases of HCC by immunohistochemical staining. Moreover, in human HCC cell lines of HepG2 and high metastatic HCCLM3, the secretory BDNF in supernatant was measured by ELISA, the effects of BDNF neutralizing antibody or Trk tyrosine kinase inhibitor K252a on apoptosis and invasion were examined by flow cytometry and transwell assay respectively. Higher expression of BDNF (63.1%) or positive expression of TrkB (55.4%) was found in HCC specimens, which was significantly correlated with multiple and advanced stage of HCC. BDNF secretory level in HCCLM3 was higher than that in HepG2 cells. Both anti-BDNF and K252a effectively induced apoptosis and suppressed invasion of HepG2 and HCCLM3 cells. These findings suggested that BDNF/TrkB are essential for HCC cells survival and invasion. BDNF/TrkB signaling should probably be an effective target to prevent HCC advancement.Journal of Experimental & Clinical Cancer Research 01/2011; 30:97. · 3.07 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Anoikis is apoptosis initiated upon cell detachment from the native extracellular matrix. Since survival upon detachment from basement membrane is required for metastasis, the ability to resist anoikis contributes to the metastatic potential of breast tumors. miR-200c, a potent repressor of epithelial to mesenchymal transition, is expressed in luminal breast cancers, but is lost in more aggressive basal-like, or triple negative breast cancers (TNBC). We previously demonstrated that miR-200c restores anoikis sensitivity to TNBC cells by directly targeting the neurotrophic receptor tyrosine kinase, TrkB. In this study, we identify a TrkB ligand, neurotrophin 3 (NTF3), as capable of activating TrkB to induce anoikis resistance, and show that NTF3 is also a direct target of miR-200c. We present the first evidence that anoikis resistant TNBC cells up-regulate both TrkB and NTF3 when suspended, and show that this up-regulation is necessary for survival in suspension. We further demonstrate that NF-κB activity increases 6 fold in suspended TNBC cells, and identify RelA and NF-κB1 as the transcription factors responsible for suspension-induced up-regulation of TrkB and NTF3. Consequently, inhibition of NF-κB activity represses anoikis resistance. Taken together, our findings define a critical mechanism for transcriptional and post-transcriptional control of suspension-induced up-regulation of TrkB and NTF3 in anoikis resistant breast cancer cells.PLoS ONE 01/2012; 7(11):e49987. · 3.73 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Brain-derived neurotrophic factor (BDNF) has been observed to be elevated in solid tumors including colorectal cancer. The present study aimed to investigate the effect of modulation of BDNF at the transcription level on the cellular function of colorectal cells and to increase our understanding of its biological role in human colon cancer. An investigation of a cohort of human colorectal tissues (tumor n=66; normal n=88) using quantitative PCR and immunohistochemistry demonstrated that BDNF is aberrantly expressed in human colon cancer and a significantly raised level of BDNF is associated with its stage at diagnosis. The expression profile of BDNF in human colon cancer cell lines was evaluated using RT-PCR. A set of anti-BDNF ribozymes were used to transfect colon cancer cells in order to generate BDNF knockdown cells to evaluate the effect on growth and apoptosis. BDNF gene transcripts were successfully detected in the colon cancer cell lines, Caco-2 and HRT18. BDNF knockdown in Caco-2 and HRT18 cell lines resulted in decreased rates of growth and proliferation. Analysis of apoptosis showed that cell apoptosis was increased. It is concluded that BDNF, a neurotrophic growth factor aberrantly expressed in cancers such as colon cancer, has a profound impact on the cellular behavior of colon cancer cells and that BDNF is associated with a reduction in the apoptosis of colon cancer. BDNF is therefore a potential therapeutic target in colon cancer and its effect in human colon cancer requires further investigation.Experimental and therapeutic medicine 12/2013; 6(6):1475-1481. · 0.34 Impact Factor