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  • Two naturally derived small molecules disrupt the sineoculis homeobox homolog 1-eyes absent homolog 1 (SIX1-EYA1) interaction to inhibit colorectal cancer cell growth.

Two naturally derived small molecules disrupt the sineoculis homeobox homolog 1-eyes absent homolog 1 (SIX1-EYA1) interaction to inhibit colorectal cancer cell growth.

Chinese medical journal (2021-09-26)
Jing Wu, Bin Huang, Hong-Bo He, Wen-Zhu Lu, Wei-Guo Wang, Hong Liu
ABSTRACT

Emerging evidence indicates that the sineoculis homeobox homolog 1-eyes absent homolog 1 (SIX1-EYA1) transcriptional complex significantly contributes to the pathogenesis of multiple cancers by mediating the expression of genes involved in different biological processes, such as cell-cycle progression and metastasis. However, the roles of the SIX1-EYA1 transcriptional complex and its targets in colorectal cancer (CRC) are still being investigated. This study aimed to investigate the roles of SIX1-EYA1 in the pathogenesis of CRC, to screen inhibitors disrupting the SIX1-EYA1 interaction and to evaluate the efficiency of small molecules in the inhibition of CRC cell growth. Real-time quantitative polymerase chain reaction and western blotting were performed to examine gene and protein levels in CRC cells and clinical tissues (collected from CRC patients who underwent surgery in the Department of Integrated Traditional and Western Medicine, West China Hospital of Sichuan University, between 2016 and 2018, n = 24). In vivo immunoprecipitation and in vitro pulldown assays were carried out to determine SIX1-EYA1 interaction. Cell proliferation, cell survival, and cell invasion were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, clonogenic assay, and Boyden chamber assay, respectively. The Amplified Luminescent Proximity Homogeneous Assay Screen (AlphaScreen) method was used to obtain small molecules that specifically disrupted SIX1-EYA1 interaction. CRC cells harboring different levels of SIX1/EYA1 were injected into nude mice to establish tumor xenografts, and small molecules were also injected into mice to evaluate their efficiency to inhibit tumor growth. Both SIX1 and EYA1 were overexpressed in CRC cancerous tissues (for SIX1, 7.47 ± 3.54 vs.1.88 ± 0.35, t = 4.92, P = 0.008; for EYA1, 7.61 ± 2.03 vs. 2.22 ± 0.45, t = 6.73, P = 0.005). The SIX1/EYA1 complex could mediate the expression of two important genes including cyclin A1 (CCNA1) and transforming growth factor beta 1 (TGFB1) by binding to the myocyte enhancer factor 3 consensus. Knockdown of both SIX1 and EYA1 could decrease cell proliferation, cell invasion, tumor growth, and in vivo tumor growth (all P < 0.01). Two small molecules, NSC0191 and NSC0933, were obtained using AlphaScreen and they could significantly inhibit the SIX1-EYA1 interaction with a half-maximal inhibitory concentration (IC50) of 12.60 ± 1.15 μmol/L and 83.43 ± 7.24 μmol/L, respectively. Administration of these two compounds could significantly repress the expression of CCNA1 and TGFB1 and inhibit the growth of CRC cells in vitro and in vivo. Overexpression of the SIX1/EYA1 complex transactivated the expression of CCNA1 and TGFB1, causing the pathogenesis of CRC. Pharmacological inhibition of the SIX1-EYA1 interaction with NSC0191 and NSC0933 significantly inhibited CRC cell growth by affecting cell-cycle progression and metastasis.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-SIX1 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution
Sigma-Aldrich
Formaldehyde solution, ACS reagent, 37 wt. % in H2O, contains 10-15% Methanol as stabilizer (to prevent polymerization)
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Leukocyte Peroxidase (Myeloperoxidase) Kit, DAB substrate kit
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Chromatin Immunoprecipitation (ChIP) Assay Kit, Contains all necessary reagents to perform 22 individual chromatin immunoprecipitation (ChIP) reactions using inexpensive protein A agarose beads.
Roche
Cell Proliferation Kit I (MTT)
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Crystal Violet, certified by the Biological Stain Commission
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IPTG, ≥99% (TLC), ≤0.1% Dioxane
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Fetal Bovine Serum, USA origin, sterile-filtered, suitable for cell culture, suitable for hybridoma
Sigma-Aldrich
QCM ECMatrix Cell Invasion Assay, 24-well (8 µm), colorimetric, The CHEMICON Cell Invasion Assay Kit uses a 24-well plate, with 8 um pores, which provides an efficient system for evaluating the invasion of tumor cells through a basement membrane model.
Sigma-Aldrich
Anti-EYA1 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody