Original Paper

Oncogene (2005) 24, 3759−3773. doi: 10.1038/sj.onc.1208452 Published online 14 March 2005
Published online 14 March 2005

alphaVbold italic beta3 integrin regulates heregulin (HRG)-induced cell proliferation and survival in breast cancer

Luciano Vellon1,2, Javier A Menendez1,2 and Ruth Lupu1,2

  1. 1Department of Medicine, Breast Cancer Translational Research Laboratory, Evanston Northwestern Healthcare Research Institute, 1001 University place, Evanston, IL 60201, USA
  2. 2Northwestern University Feinberg School of Medicine, Chicago, IL, USA

Correspondence: R Lupu, E-mail: [email protected]

Received 14 September 2004; Revised 08 December 2004; Accepted 08 December 2004; Published online 14 March 2005.



alphavbeta3 integrin-overexpression in tumor associated vasculature is a marker of poor prognosis in breast cancer. A positive correlation between alphavbeta3 integrin and overexpression of Heregulin (HRG), a growth factor associated with breast cancer aggressiveness was recently demonstrated. Here, we addressed the role of alphavbeta3 in the proliferation and survival of HRG-overexpressing breast cancer models. Expression of the RGD-binding integrins alphavbeta3, alphavbeta5 and alphavbeta6 was assessed in the HRG-overexpressing breast cancer cells MDA-MB-231, Hs578T (231/WT and Hs578T/WT, respectively) and derived cells transfected with the antisense orientation of the HRG-beta2 full-length cDNA (231/ASPOOL, 231/AS31 and Hs578T/AS15). Interestingly, only alphavbeta3 expression was noticeably decreased by blockade of HRG expression in the 231/ASPOOL, 231/AS31 and Hs578T/AS15 cells. Small RGD-based peptidomimetic alphavbeta3 antagonists significantly decreased cell viability and anchorage-dependent cell growth of HRG-overexpressing cells, while the low-HRG-expressing 231/AS31 cells did not show a significant response. Mechanistically, functional blockade of alphavbeta3 impaired HRG-promoted hyperactivation of ERK1/ERK2 MAPK without altering the activation of AKT. Flow cytometric analysis of the cell cycle demonstrated that alphavbeta3 antagonists significantly decreased S- and G2/M-phase subpopulations of 231/WT and control 231/VEC cells. Comparable, this effect was linked to an increase in the levels and nuclear translocation of the CDKs inhibitor p27Kip1. Besides downregulating alphavbeta3 and its driven signaling, HRG blockade led to decreased levels of CYR61 in 231/ASPOOL and 231/AS31 cells. Considering that CYR61 is sufficient to upregulate the expression of alphavbeta3, we then assessed alphavbeta3 levels in MDA-MB-231 cell derivatives expressing the antisense orientation of the CYR61 cDNA (231/CYR61AS-5 and 231/CYR61AS-8). Remarkably, downregulation of CYR61 drastically decreased the levels of alphavbeta3 in the 231/CYR61-5 and 231/CYR61-8 cells, providing further evidence of a key role for CYR61 in HRG-dependent alphavbeta3 overexpression. Moreover, blockade of CYR61 expression impaired the HRG-induced hyperactivation of ERK1/ERK2 MAPK without altering the activation status of AKT in MDA-MB-231 cells, thus resembling the effects exerted by the downregulation of HRG expression as well as by functional blockade of alphavbeta3. These results indicate that HRG is regulating alphavbeta3 levels as well as alphavbeta3-triggered signaling through its downstream effector, CYR61, in highly invasive breast cancer cells. Altogether, the data presented here provide evidence of a CYR61-regulatory role on alphavbeta3 integrin expression in the modulation of uncontrolled growth of HRG-overexpressing breast carcinomas. This work supports additional studies concerning the use of integrin antagonists as dual therapeutic agents in breast cancer, targeting both, endothelial and tumor cells.


Heregulin, alphaVbeta3, integrins, S-247, breast cancer

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