Norcantharidin impairs tumor growth in vivo and inhibits stemness of triple-negative breast cancer cells

DAMIAN E. BERARDI; GUIDO CICUTTIN; AGUSTINA TARUSELLI; STÉFANO M. CIRIGLIANO; ELISA D. BAL DE KIER JOFFÉ; ALEJANDRO J. URTREGER; LAURA B. TODARO

Whasington

Congreso; 108th Annual Meeting of the American Associaton for Cancer Research; 2017

American Associaton for Cancer Research (AACR)

Triple-negative breast cancer (TNBC) is characterized by an abundance of treatment-resistant cancer stem cells (CSC). The absence of a molecular target, coupled with its highly aggressiveness, leads to the lack of an effective therapy for TNBC. Norcantharidin (NCTD) is a synthetic demethylated small-molecule analog of the naturally occurring cantharidin isolated from blister beetles (Mylabris phalerata Pall). Unlike the conventional chemotherapeutics, NCTD toxicity is higher to cancer cells than normal ones, making this small molecule promising for cancer treatment. The aims of this work were: A) To study the effect of NCTD on 4T1 cell line proliferation in vitro. B) To analyze the effect of NCTD on 4T1 derived CSC on self-renewal and clonogenic capacity. C) To evaluate the effect of NCTD on 4T1 tumor growth in vivo. We employed the well-known 4T1 triple-negative breast cancer cell model, which presents a huge proportion of CSC. We observed that NCTD treatment during 96 h significantly reduced 4T1 cell proliferation in vitro. In addition, the IC50 value of NCTD was 27.35+2.83 uM. Related to CSC, NCTD pre-treatment for 96 h impaired CSC self-renewal (Number of secondary mammospheres: Control: 276+39; NCTD: 163+18) as well as the clonogenic capacity (Number of colonies: Control: 359+38; NCTD: 122+11). By q-PCR, we observed that NCTD treatment for 48 h significantly induced an increase of Gli-1 and Smooth in CSC, keys member of Sonic Hedgehog pathway. Finally, we performed an in vivo assay, where 4T1 cells were orthotopically inoculated on mammary gland of BALB/c mice, and NCTD was i.p. inoculated twice a week (5mg/kg). We observed that NCTD treatment significantly reduced tumor growth in vivo. Our data suggest that NCTD treatment reduces tumor growth both in vitro and in vivo, possibly through the direct effect on CSC self-renewal and clonogenic capacity, by modulating Sonic Hedgehog pathway.