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Contents lists available at ScienceDirect
Cancer Letters
journal homepage: www.elsevier.com/locate/canlet
Original Articles
C-terminal HSP90 inhibitor L80 elicits anti-metastatic effects in triple-negative breast cancer via STAT3 inhibition 
T
Tae-Min Choa,b,1, Ji Young Kima,1, Yoon-Jae Kima,c, Daeil Sunga,b, Eunhye Oha,b, Seojin Janga,b, Lee Farrandd, Van-Hai Hoange, Cong-Truong Nguyene, Jihyae Anne, Jeewoo Leee,∗∗, Jae Hong Seoa,b,∗ a Division of Medical Oncology, Department of Internal Medicine, Korea University College of Medicine, Korea University, Seoul, 152-703, Republic of Korea b Brain Korea 21 Program for Biomedical Science, Korea University College of Medicine, Korea University, Seoul, 152-703, Republic of Korea c Department of Biomedical Research Center, Korea University Guro Hospital, Korea University, Seoul, 08308, Republic of Korea d AusHealth Research, 65 Hardys Rd, Underdale, Adelaide, South Australia, 5032, Australia e Laboratory of Medicinal Chemistry, College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea
Keywords:
C-terminal HSP90 inhibitor
Triple-negative breast cancer
Cancer stem cells
STAT3
Metastasis 
Triple-negative breast cancer (TNBC) is an aggressive heterogeneous disease with a divergent profile. It has an earlier tendency to form metastases and is associated with poor clinical outcomes due to the limited treatment options available. Heat-shock protein (HSP90) represents a potential treatment target as it promotes tumor progression and metastasis by modulating the maturation and stabilization of signal transduction proteins. We sought to investigate the efficacy of the C-terminal HSP90 inhibitor L80 on cell proliferation, breast cancer stem cell (BCSC)-like properties, tumor growth and metastasis. L80 suppressed cell viability and concomitantly in-hibited AKT/MEK/ERK/JAK2/STAT3 signaling in TNBC cells but did not induce cytotoxicity in normal cells. L80 effectively targeted BCSC-like traits, together with significant reductions in the CD44high/CD24low-population, ALDH1 activity and mammosphere forming-ability. In support of the in vitro observations, L80 administration caused significant impairment in tumor growth, angiogenesis and distant metastases in an orthotopic allograft model with BCSC-enriched cells in vivo. These phenomena were associated with the suppression of BCSC-like characteristics and STAT3 dysfunction. Our findings highlight properties of the L80 compound that may be useful in suppressing metastatic TNBC.
1. Introduction