RAC1B function is essential for breast cancer stem cell maintenance and chemoresistance of breast tumor cells

Fuhui Chen, Sevim B. Gurler, David Novo, Cigdem Selli, Denis G. Alferez, Secil Eroglu, Kyriaki Pavlou, Jingwei Zhang, Andrew H. Sims, Neil E. Humphreys, Antony Adamson, Andrew Campbell, Owen J. Sansom, Cathy Tournier, Robert B. Clarke, Keith Brennan, Charles H. Streuli, Ahmet Ucar

Research output: Contribution to journalArticlepeer-review


Breast cancer stem cells (BCSC) are presumed to be responsible for treatment resistance, tumor recurrence and metastasis of breast tumors. However, development of BCSC-targeting therapies has been held back by their heterogeneity and the lack of BCSC-selective molecular targets. Here, we demonstrate that RAC1B, the only known alternatively spliced variant of the small GTPase RAC1, is expressed in a subset of BCSCs in vivo and its function is required for the maintenance of BCSCs and their chemoresistance to doxorubicin. In human breast cancer cell line MCF7, RAC1B is required for BCSC plasticity and chemoresistance to doxorubicin in vitro and for tumor-initiating abilities in vivo. Unlike Rac1, Rac1b function is dispensable for normal mammary gland development and mammary epithelial stem cell (MaSC) activity. In contrast, loss of Rac1b function in a mouse model of breast cancer hampers the BCSC activity and increases their chemosensitivity to doxorubicin treatment. Collectively, our data suggest that RAC1B is a clinically relevant molecular target for the development of BCSC-targeting therapies that may improve the effectiveness of doxorubicin-mediated chemotherapy.

Original languageEnglish
Pages (from-to)679-692
Number of pages14
Early online date5 Jan 2023
Publication statusPublished - 24 Feb 2023

Research Beacons, Institutes and Platforms

  • Manchester Cancer Research Centre


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