Abstract LB111: Drug repurposing of niclosamide to regulate Wnt/beta-catenin signaling pathway through upregulating SFRP1 in colorectal cancer
Authors: Wu Mia Mingxia , Tong Christy Wing Sum , Yan Vivi Wei , To Kenneth Kin-wah 
Published: July 2021

Abstract
Aim: This study investigated the inhibition of proliferation and invasiveness of colorectal cancer (CRC) by niclosamide via targeting the secreted Frizzled-related protein 1 (SFRP1) and the Wnt/beta-catenin signaling pathway. Background: CRC is the third most common cancer worldwide. Aberrant activation of various signaling pathways in CRC leads to its poor response to chemotherapy. Hyperactivation of Wnt/beta-catenin pathway is known to drive cell proliferation, invasion, and migration of CRC. Epigenetic silencing of extracellular Wnt inhibitors, such as secreted Frizzled-related proteins (SFRPs), has been shown to stabilize beta-catenin and subsequently activate the Wnt signaling pathway. Niclosamide is a clinically approved drug indicated for the treatment of tapeworm infections. We have recently reported the repurposing of niclosamide to potentiate chemotherapeutic drugs for treating CRC by STAT3 inhibition. Niclosamide was also reported to be a Wnt/beta-catenin inhibitor but the precise mechanism is not clear. Methods: The antiproliferative effect was assessed by MTT assay and colony formation assay. The mRNA level, protein expression, and methylation status of SFRP1, and sets of SFRP1 co-expressed genes in CRC were analyzed by the TCGA data portal. The mRNA expression of SFRP1 and CpG island methylator phenotype (CIMP) marker genes were measured by qRT-PCR. DNA methylation was analyzed by bisulfite genomic sequencing. Inhibition of Wnt/beta-catenin and its downstream targets were examined by Western blot analysis. Cell migration and invasion were investigated by wound healing and transwell chamber migration assay. The intracellular localization of beta-catenin was determined by immunofluorescence assay. Results: Niclosamide inhibited HCT116 cell proliferation and colony formation in a concentration-dependent manner. Compared with normal colon tissues, CRC expressed significantly lower level of SFRP1 mRNA. SFRP1 methylation was inversely correlated with its mRNA expression. The DNA-demethylating agent 5-azacytidine was shown to restore expression of SFRP1 and CIMP panel genes in HCT116 cells after 5-day treatment. However, SFRP1 mRNA level was only upregulated by 1-day niclosamide treatment, but not 3-day niclosamide treatment. The upregulation of SFRP1 by niclosamide was found not relevant to DNA demethylation according to bisulfite genomic sequencing data. Immunofluorescence and Western blotting analysis showed that the increased SFRP1 expression was accompanied by reduced expression and nuclear accumulation of beta-catenin. Moreover, a low concentration of niclosamide that has minimal effect on cell proliferation, was shown to significantly suppress migration and invasion of HCT116 cells. Conclusion: Niclosamide is a promising candidate for drug repurposing. It was shown to upregulate SFRP1 and subsequently suppress Wnt/beta-catenin signaling, thereby impairing CRC cell migration and invasion. Upregulation of SFRP1 by niclosamide was not dependent on DNA demethylation.
Citation Format: Mia Mingxia Wu, Christy Wing Sum Tong, Vivi Wei Yan, Kenneth Kin-wah To. Drug repurposing of niclosamide to regulate Wnt/beta-catenin signaling pathway through upregulating SFRP1 in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB111.