Potential therapeutic effect of targeting glycogen synthase kinase 3\u03b2 in esophageal squamous cell carcinoma

Dilireba Bolidong,Tomoharu Miyashita,Masahiro Uehara,Toshinari Minamoto,Takahiro Domoto,Itasu Ninomiya,Richard W Wong,Hemragul Sabit,Mitsutoshi Nakada,Tomoyuki Okumura,Yoshio Endo

doi:10.1038/s41598-020-68713-9

Abstract

Esophageal squamous cell carcinoma (ESCC) is a common gastrointestinal cancer and is often refractory to current therapies. Development of efficient therapeutic strategies against ESCC presents a major challenge. Glycogen synthase kinase (GSK)3β has emerged as a multipotent therapeutic target in various diseases including cancer. Here we investigated the biology and pathological role of GSK3β in ESCC and explored the therapeutic effects of its inhibition. The expression of GSK3β and tyrosine (Y)216 phosphorylation-dependent activity was higher in human ESCC cell lines and primary tumors than untransformed esophageal squamous TYNEK-3 cells from an ESCC patient and tumor-adjacent normal esophageal mucosa. GSK3β-specific inhibitors and small interfering (si)RNA-mediated knockdown of GSK3β attenuated tumor cell survival and proliferation, while inducing apoptosis in ESCC cells and their xenograft tumors in mice. GSK3β inhibition spared TYNEK-3 cells and the vital organs of mice. The therapeutic effect of GSK3β inhibition in tumor cells was associated with G0/G1- and G2/M-phase cell cycle arrest, decreased expression of cyclin D1 and cyclin-dependent kinase (CDK)4 and increased expression of cyclin B1. These results suggest the tumor-promoting role of GSK3β is via cyclin D1/CDK4-mediated cell cycle progression. Consequently, our study provides a biological rationale for GSK3β as a potential therapeutic target in ESCC.

Highlights

Esophageal squamous cell carcinoma (ESCC) is a common gastrointestinal cancer and is often refractory to current therapies
phosphate buffered saline (PBS) Phosphate buffered saline pGSK3βS9 GSK3β phosphorylated in S9 residue pGSK3βY216 GSK3β phosphorylated in Y216 residue pGSS641 Glycogen synthase (GS) phosphorylated at S641 residue propidium iodide (PI) Propidium iodide S Serine standard deviations (SDs)(s) Standard deviation(s) siRNA Small interfering RNA TCGA The Cancer Genome Atlas TUNEL Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling Y Tyrosine
The expression levels of GSK3β and its Y216 phosphorylated fraction were higher in all ESCC cell lines compared to normal esophageal squamous TYNEK-3 cells (Fig. 1A), with less detectable S9 phosphorylation

Summary

Introduction

Esophageal squamous cell carcinoma (ESCC) is a common gastrointestinal cancer and is often refractory to current therapies. The therapeutic effect of GSK3β inhibition in tumor cells was associated with G0/G1- and G2/M-phase cell cycle arrest, decreased expression of cyclin D1 and cyclin-dependent kinase (CDK)[4] and increased expression of cyclin B1 These results suggest the tumor-promoting role of GSK3β is via cyclin D1/CDK4-mediated cell cycle progression. Accumulating studies indicate that esophageal squamous cell carcinogenesis is initiated by a combination of extrinsic/environmental (e.g., alcohol, cigarette smoking) and intrinsic (e.g., acetaldehyde, an intermediate metabolite of alcohol) carcinogenic factors[2,4,5] These carcinogenic stimuli cause ESCC to develop through a sequential transformation of squamous epithelial cells to squamous dysplasia (mild to severe, or low-grade and high-grade intraepithelial neoplasia), intraepithelial (in situ) SCC, and progressing to invasive S CC14. We hypothesized that GSK3β is aberrantly expressed and/or activated in ESCC

Methods

Results

Conclusion