VEGF-neuropilin-2 signaling promotes stem-like traits in breast cancer cells by TAZ-mediated repression of the Rac GAP beta2-chimaerin
Department of Molecular, Cell and Cancer Biology; Medical Scientist Training Program; Graduate School of Biomedical Sciences, MD/PhD Program; UMass Metabolic Network
Amino Acids, Peptides, and Proteins | Cancer Biology | Cell Biology | Enzymes and Coenzymes | Genetic Phenomena | Neoplasms
The role of vascular endothelial growth factor (VEGF) signaling in cancer is not only well known in the context of angiogenesis but also important in the functional regulation of tumor cells. Autocrine VEGF signaling mediated by its co-receptors called neuropilins (NRPs) appears to be essential for sustaining the proliferation and survival of cancer stem cells (CSCs), which are implicated in mediating tumor growth, progression, and drug resistance. Therefore, understanding the mechanisms involved in VEGF-mediated support of CSCs is critical to successfully treating cancer patients. The expression of the Hippo effector TAZ is associated with breast CSCs and confers stem cell-like properties. We found that VEGF-NRP2 signaling contributed to the activation of TAZ in various breast cancer cells, which mediated a positive feedback loop that promoted mammosphere formation. VEGF-NRP2 signaling activated the GTPase Rac1, which inhibited the Hippo kinase LATS, thus leading to TAZ activity. In a complex with the transcription factor TEAD, TAZ then bound and repressed the promoter of the gene encoding the Rac GTPase-activating protein (Rac GAP) beta2-chimaerin. By activating GTP hydrolysis, Rac GAPs effectively turn off Rac signaling; hence, the TAZ-mediated repression of beta2-chimaerin resulted in sustained Rac1 activity in CSCs. Depletion of beta2-chimaerin in non-CSCs increased Rac1 activity, TAZ abundance, and mammosphere formation. Analysis of a breast cancer patient database revealed an inverse correlation between beta2-chimaerin and TAZ expression in tumors. Our findings highlight an unexpected role for beta2-chimaerin in a feed-forward loop of TAZ activation and the acquisition of CSC properties.
DOI of Published Version
Sci Signal. 2018 May 1;11(528). pii: eaao6897. doi: 10.1126/scisignal.aao6897. Link to article on publisher's site
Elaimy, Ameer L.; Guru, Santosh; Chang, Cheng; Ou, Jianhong; Amante, John J.; Zhu, Lihua Julie; Goel, Hira Lal; and Mercurio, Arthur M., "VEGF-neuropilin-2 signaling promotes stem-like traits in breast cancer cells by TAZ-mediated repression of the Rac GAP beta2-chimaerin" (2018). University of Massachusetts Medical School Faculty Publications. 1593.