The Tissue-Reconstructing Ability of Colon CSCs Is Enhanced by FK506 and Suppressed by GSK3 Inhibition.

Ryo Ishida,Michiyo Koyanagi-Aoi,Nobu Oshima,Yoshihiro Kakeji,Takashi Aoi

doi:10.1158/1541-7786.mcr-17-0071

Ryo Ishida, Michiyo Koyanagi-Aoi + Show 3 more

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https://doi.org/10.1158/1541-7786.mcr-17-0071

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Abstract

Cancer stem cells (CSC) are capable of reconstructing cancer tissues, are involved in both recurrence and metastasis, and contribute to therapeutic resistance. Therefore, elucidating the molecular mechanism in CSCs is important to successfully treat unresectable cancers. Previously, we observed that colon cancer stem-like cells can be induced from human colon cancer cell lines by retrovirally introducing OCT3/4, SOX2, and KLF4, and we have designated such cells as induced cancer stem cells (iCSC). In the current study, we used iCSCs to evaluate the molecular mechanism of colon CSCs and developed new methods to control them. The spheres that were derived in vitro from the iCSCs, but not those from parental cells, mimicked human colon cancer tissues in terms of their immunohistologic patterns; therefore, sphere-forming ability was assessed as a measure of the tissue-reconstructing ability of iCSCs. Interestingly, the calcineurin inhibitor FK506 enhanced the sphere-forming ability of iCSCs, whereas GSK3 inhibition by RNAi, CHIR99021, and valproic acid (VPA) impeded the sphere-forming ability and expansion of iCSCs. FK506 and GSK3 inhibition showed the opposite effect regarding the NFATc3 localization of iCSCs. These data reveal the crucial role that NFAT localization, as regulated by calcineurin and GSK3, plays in the tissue-reconstructing ability of colon cancer stem cells and the potential of GSK3 inhibitors, such as VPA, in colon cancer stem cell-targeting therapy.Implications: This study identifies signaling pathways that contribute to the tissue-reconstructing capacity of colon CSCs and suggests that clinically used drugs could be repurposed to improve unresectable colon cancers. Mol Cancer Res; 15(10); 1455-66. ©2017 AACR.

Highlights

Colorectal cancer is the third most common malignancy worldwide after lung and breast cancer
We used three viral vectors that separately carried OCT3/4, SOX2, or KLF4 to generate the induced cancer stem cells (iCSC) from a SW480 human colon cancer cell line [4]
To avoid heterogeneity, which could hinder the identification of the molecular signature of the iCSCs, we constructed a polycistronic retroviral vector in which the three cDNAs encoding OCT3/4, KLF4, and SOX2 were connected with the T2A sequences

Summary

Introduction

Colorectal cancer is the third most common malignancy worldwide after lung and breast cancer. Nearly 1.4 million patients are diagnosed with and more than 600,000 patients die from colorectal cancer each year [1]. About half of all such patients develop metastases, and most of these cases have unresectable tumors. Various drugs, such as chemotherapy and molecular target therapy, have been developed, most of the cases with unresectable tumors cannot be cured. Recent evidence suggests that only a subset of cancer cells, called cancer stem cells (CSC), is capable of reconstructing cancer. Note: Supplementary data for this article are available at Molecular Cancer Research Online (http://mcr.aacrjournals.org/).

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