Treating triple-negative breast cancer by a combination of rapamycin and cyclophosphamide: an in vivo bioluminescence imaging study.

Published

Journal Article

Rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, has been shown to inhibit the growth of oestrogen positive breast cancer. However, triple-negative (TN) breast cancer is resistant to rapamycin treatment in vitro. We set to test a combination treatment of rapamycin with DNA-damage agent, cyclophosphamide, in a TN breast cancer model. By binding to and disrupting cellular DNA, cyclophosphamide kills cells via interfering with their normal functions. We assessed the responses of nude mice bearing tumour xenografts of TN MDA-MB-231 cells to the combination of rapamycin and cyclophosphamide in both orthotopic mammary and lung-metastasis models. We tracked tumour growth and metastasis by bioluminescent imaging and examined the expression of Ki67, CD34 and HIF-1alpha in tumour tissues by immunohistochemistry and apoptosis index with TUNEL assay, and found that MDA-MB-231 cells are sensitive to rapamycin therapy in orthotopic mammary, but not in lung with metastasis. Rapamycin when combined with cyclophosphamide is found to have a more significant effect in reducing tumour volume and metastasis with a much improved survival rate. Our data also show that the sensitivity of TN tumours to rapamycin is associated with the microenvironment of the tumour cells. The data indicate that in a relatively hypoxic environment HIF-1alpha may play a role in mediating the anti-cancer effect of rapamycin and cyclophosphamide may prevent the feedback activation of Akt by rapamycin. Overall our results show that rapamycin plus cyclophosphamide can achieve an improved efficacy in suppressing tumour growth and metastasis, suggesting that the combination therapy can be a promising treatment option for TN cancer.

Full Text

Duke Authors

Cited Authors

  • Zeng, Q; Yang, Z; Gao, Y-J; Yuan, H; Cui, K; Shi, Y; Wang, H; Huang, X; Wong, STC; Wang, Y; Kesari, S; Ji, R-R; Xu, X

Published Date

  • April 2010

Published In

Volume / Issue

  • 46 / 6

Start / End Page

  • 1132 - 1143

PubMed ID

  • 20156674

Pubmed Central ID

  • 20156674

Electronic International Standard Serial Number (EISSN)

  • 1879-0852

Digital Object Identifier (DOI)

  • 10.1016/j.ejca.2010.01.014

Language

  • eng

Conference Location

  • England