Blockage of tropomyosin receptor kinase a (TrkA) enhances chemo-sensitivity in breast cancer cells and inhibits metastasis in vivo

Abstract

Hyper-activation of the Neurotrophin Receptor Signaling contributes to the development and metastasis of breast cancer. The inhibition of growth factor-dependent growth of breast cancer cell demonstrated a promising way for cancer therapy. In this study, the signaling pathway of tropomyosin receptor kinase A (TrkA) had been investigated for the role it played in the proliferation of chemo-resistance of breast cancer cells. Small interference RNA (siRNA) was used to down-regulate the expression of TrkA in breast cancer cell and tumor xenograft mice model. Our results indicated that siRNA mediated down-regulation of TrkA lead to the proliferation inhibition of cancer cells and arrested cells cycle at G0/G1 phase via inactivation of NF-κBp65. Application of TrkA siRNA to cancer cell also increased the chemo-sensitivity to paclitaxel, and further promoted apoptosis in cancer cell through the activation of caspase-3. Moreover, TrkA siRNA increased the efficacy of paclitaxel and decreased the incidence of lung metastasis in tumor xenografted mice. In sum, these results indicate that TrkA signaling plays an important role in breast cancer chemo-resistance and metastasis. It could be a potential pharmacologic target to enhance the effectiveness of chemo-therapy for breast cancer.

Keywords: TrkA; breast cancer; metastasis; siRNA.

Figure 1

Verification of siRNA transfection. A. Expression of TrkA mRNA in MCF-7 human breast cancer cells. B. Expression of TrkA protein in MCF-7 human breast cancer cells. *P<0.05.

Figure 2

TrkA siRNA inhibits NGF-induced proliferation and NF-κB p65 activity. A. Cell viabilities in different groups; B. Cell cycle distributions in three groups; C. Flow Cytometry picture for cell cycle analysis; D. Activities of NF-κBp65 after treatment. *P<0.05.

Figure 3

The Synergistic Effects of paclitaxel on TrkA siRNA-mediated proliferation inhibition. A. Cell viabilities in different groups. B. Cell morphological changes after treatment. C. Activation of caspase-3 in different groups. Values are means of three independent experiments. D. Relative intensity of bands. *P<0.05.

Figure 4

TrkA siRNA in combination with paclitaxel inhibits tumor growth and lung metastasis. A. Significant decrement in tumor mass in siRNA group. B. Normal and metastatic lung tissue.