# ICAT mediates the inhibition of stemness and tumorigenesis in acute myeloid leukemia cells induced by 1,25-(OH)2D3

## TL;DR

This study shows that vitamin D inhibits leukemia cell stemness and tumor growth, possibly by interacting with the ICAT protein.

## Contribution

The study identifies ICAT as a mediator of 1,25-(OH)2D3's anti-leukemic effects on stemness and tumorigenesis.

## Key findings

- 1,25-(OH)2D3 inhibits proliferation and stemness of AML cells and promotes monocyte differentiation.
- ICAT knockdown reduces the inhibitory effects of 1,25-(OH)2D3, while ICAT overexpression enhances them.
- ICAT modulates the Wnt/β-catenin signaling pathway in response to 1,25-(OH)2D3 in AML cells.

## Abstract

The role of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) in cancer prevention and treatment is an emerging topic of interest. However, its effects on the stemness of acute myeloid leukemia (AML) cells are poorly understood.

The proliferation and differentiation of AML cells (HL60 and NB4) were investigated by the CCK-8 assay, immunocytochemical staining, and flow cytometry. The abilities of HL60 and NB4 cells to form spheres were examined by the cell sphere formation assay. In addition, the levels of stemness-associated markers (SOX2, Nanog, OCT4, and c-Myc) in HL60 and NB4 cells were measured by western blotting and quantitative real-time polymerase chain reaction. Moreover, we obtained β-catenin-interacting protein 1 (ICAT)-knockout and ICAT-overexpressing HL-60 cells using gene editing and lentiviral infection techniques and investigated the role of ICAT in modulating the stemness-inhibiting effects of 1,25-(OH)2D3 using the aforementioned experimental methods. Finally, we validated our findings in vivo using NOD/SCID mice.

1,25-(OH)2D3 inhibited the proliferation and stemness of AML cells (HL60 and NB4) and induced their differentiation into monocytes. Additionally, the knockdown of ICAT in HL60 cells attenuated the inhibitory effects of 1,25-(OH)2D3 on proliferation and stemness and suppressed the expression of stemness markers. Conversely, overexpression of ICAT enhanced the aforementioned inhibitory effects of 1,25-(OH)2D3. Consistently, in NOD/SCID mice, 1,25-(OH)2D3 suppressed tumor formation by HL-60 cells, and the effects of ICAT knockdown or overexpression on 1,25-(OH)2D3 aligned with the in vitro findings.

1,25-(OH)2D3 inhibits AML cell stemness, possibly through modulation of the ICAT-mediated Wnt/β-catenin signaling pathway.