Serine/threonine-protein kinase 24 is an inhibitor of gastric cancer metastasis through suppressing CDH1 gene and enhancing stemness

Yi-Ling Chen; Chih-Yang Wang; Jung-Hua Fang; Hui-Ping Hsu

Serine/threonine-protein kinase 24 is an inhibitor of gastric cancer metastasis through suppressing CDH1 gene and enhancing stemness

Am J Cancer Res. 2021 Sep 15;11(9):4277-4293. eCollection 2021.

Authors

Yi-Ling Chen^{1

2}, Chih-Yang Wang^{3

4}, Jung-Hua Fang⁵, Hui-Ping Hsu⁶

Affiliations

¹ Department of Senior Citizen Service Management, Chia Nan University of Pharmacy and Science Tainan, Taiwan.
² Department of Health and Nutrition, Chia Nan University of Pharmacy and Science Tainan, Taiwan.
³ Ph.D. Program for Cancer Molecular Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University Taipei, Taiwan.
⁴ Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University Taipei, Taiwan.
⁵ Laboratory Animal Center, College of Medicine, National Cheng Kung University Tainan, Taiwan.
⁶ Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University Tainan, Taiwan.

PMID: 34659887
PMCID: PMC8493374

Abstract

Gastric cancer patients often present with distant metastasis and advanced stages. Suppressing serine/threonine-protein kinase 24 (STK24, also known as MST3) is known to promote gastric tumorigenesis. Here, we investigated the effects from STK24 on the metastasis of gastric cancer. We used CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 technology for genetic knockout of STK24 at the genomic DNA level in human MKN45 and mouse M12 gastric cancer cells. To assess the consequences of STK24 knockdown, western blot, cell migration, and wound healing assays were conducted in vitro. An in vivo mouse model of liver metastasis was established and tested, and bioinformatics analyses were performed. The knockdown of the STK24 gene enhanced cell migration and increased liver metastasis in the mouse model of gastric cancer. STK24-silenced tumors suppressed CD4⁺ T cells and enhanced the expansion of CD11b⁺Ly6C⁺ myeloid-derived suppressor cells (MDSCs) and F4/80⁺ macrophages in the spleen of the mice. In MKN45 cells, STK24 silencing resulted in downregulation of E-cadherin (gene CDH1, Cadherin-1, or epithelial cadherin). In 38 paired specimens of gastric adenocarcinomas and normal tissues, we examined STK24 and CDH1 expression levels via western blot; a positive correlation between the expression levels of STK24 and CDH1 was found (R² = 0.5507, P = 9.72 × 10^-8). Furthermore, in Oncomine database and Kaplan-Meier plotter analysis, the loss of CDH1, increase in CCL2, and upregulation of CD44 were correlated with poor prognosis of gastric cancer patients. Our results demonstrate that knockdown of STK24 increases cell migration through suppressing CDH1 and enhancing CD44. In experimental model of metastatic gastric cancer in syngeneic inbred mice, STK24 is important for immune suppression through expansion of CD11b⁺Ly6C⁺ MDSCs and F4/80⁺ macrophages. We confirmed that STK24 is an inhibitor of gastric cancer metastasis.

Keywords: CD44; CDH1; E-cadherin; Gastric cancer; MDSC; STK24; metastasis; myeloid-derived suppressor cells; serine/threonine-protein kinase 24; stemness.