Factors Promoting Tamoxifen Resistance in Breast Cancer via Stimulating Breast Cancer Stem Cell Expansion

Author(s): Diane Ojo, Fengxiang Wei, Yun Liu, Enli Wang, Hongde Zhang, Xiaozeng Lin, Nicholas Wong, Anita Bane, Damu Tang

Journal Name: Current Medicinal Chemistry

Volume 22 , Issue 19 , 2015

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Estrogen receptor-alpha positive (ER+) breast cancer constitutes 70-75% of the disease incidence. Tamoxifen has been the basis of endocrine therapy for patients with ER+ breast cancer for more than three decades. The treatment reduces the annual mortality rate of breast cancer by 31%, and remains the most effective targeted cancer therapy. However, approximately one-third of patients treated with adjuvant tamoxifen suffer from aggressive recurrent disease. Resistance to tamoxifen, thus, remains a major challenge in providing effective treatments for these patients. In an effort to overcome the resistance, intensive research has been conducted to understand the underlying mechanisms; this has resulted in the identification of complex factors/pathways contributing to tamoxifen resistance, including modulations of the ERsignaling, upregulation of a set of growth factor receptor networks (HER2, EGFR, FGFR, and IGF1R), alterations of the PI3K-PTEN/AKT/mTOR pathway, and an elevation of the NF-κB signaling. Despite these advances, our understanding of the acquired resistance remains fragmented and there is a lack of a platform to integrate these diversified molecular factors/ pathways into a cohesive mechanistic model. Nonetheless, at the cellular level, it is becoming increasingly recongnized that cancer stem cells (CSCs) are key in driving cancer metastasis and therapy resistance. Likewise, evidence is emerging for the critical contributions of breast cancer stem cells (BCSCs) to tamoxifen resistance. In this review, we will discuss these recent developments of BCSC-mediated resistance to tamoxifen and the contributions of those demonstrated molecular factors/pathways to BCSC expansion during the emergency of tamoxifen resistance.

Keywords: Breast cancer, breast cancer stem cells, endocrine therapy, estrogen receptor, tamoxifen, tamoxifen resistance.

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Article Details

Year: 2015
Published on: 01 July, 2015
Page: [2360 - 2374]
Pages: 15
DOI: 10.2174/0929867322666150416095744
Price: $65

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