Investigations into the effects and related upstream/downstream regulatory mechanisms of long non-coding RNA WT1-AS in the maintenance and development of gastric cancer stem cells in vitro and in vivo

Abstract Background Cancer stem cells (CSCs) are proposed to be responsible for almost all malignant phenotypes (e.g. heterogeneity, uncontrolled growth, metastasis, recurrence, chemoresistance) of tumors. Long non-coding RNA WT1 antisense RNA (WT1-AS) has been found to be involved in the regulation of lung cancer cell stemness. However, the roles and molecular mechanisms of WT1-AS in the maintenance and development of gastric cancer stem cells (GSCs) have not been investigated. Methods mRNA and protein expression was measured by RT-qPCR and western blot. CCK8 and Soft agar colony formation assays were performed to assess cell viability and colony clone formation ability. Cell cycle and apoptosis were determined by flow cytometry analysis. Cell transwell and wound healing analyses were carried out to assess cell migration ability. In vitro angiogenesis and 3D spheroid cultures assays were also performed. Moreover, in vitro experiments were carried out to explore the function of WT1-AS on tumor growth, metastasis and cell stemness. The upstream transcription factors or downstream genes of WT1-AS were screened through Bioinformatics, dual-luciferase assays and RNA-sequencing (RNA-seq) technology. Results Our present study demonstrated that WT1-AS knockdown or wilms tumor 1 (WT1) overexpression improved GSC proliferative and migratory capacities, promoted GSC EMT, enhanced GSC stemness, inhibited GSC apoptosis, potentiated the resistance of GSCs to 5-FU and induced HUVEC angiogenesis in vitro. WT1-AS loss or WT1 increase facilitated the formation of in-vitro 3D GSC aggregates. WT1-AS ameliorated the malignant phenotypes of GSCs by down-regulating WT in vitro. Additionally, WT1-AS inhibited tumor growth and metastasis, and reduced tumor stemness in GSCs-derived xenografts (s.c., i.p., and i.v.) in vivo. Furthermore, XBP1 was identified as an upstream regulator of WT1-AS in GSCs. RNA-seq and RT-qPCR data suggested that PSPH, GSTO2, FYN, and PHGDH might be the downstream targets of WT1-AS in GSCs. Conclusions Our data demonstrated that WT1-AS weakened the stem-cell like behaviors and characteristics of GSCs in vitro and in vivo by down-regulating WT1. Also, some upstream regulators and downstream targets of WT1-AS were identified in GSCs. Investigations on the molecular mechanisms underlying the complex phenotypes of GSCs might contribute to the better management of headaches in cancers.