The roles and molecular mechanisms of long non-coding RNA WT1-AS in the maintenance and development of gastric cancer stem cells

It has been proposed that cancer stem cells (CSCs) are responsible for almost all malignant phenotypes of tumors. Long non-coding RNA WT1 antisense RNA (WT1-AS) has been found to be implicated in lung cancer cell stemness. However, the roles and molecular mechanisms of WT1AS in the development of gastric cancer stem cells (GCSCs) remain unknown. Our present study showed that WT1-AS negatively regulated WT1 expression in GCSCs. WT1-AS knockdown or Wilms' tumor 1 (WT1) overexpression improved GCSC proliferative and migratory capacities, inhibited GCSC apoptosis, potentiated the resistance of GCSCs to 5-FU, promoted GCSC EMT, induced HUVEC angiogenesis, enhanced GCSC stemness, and facilitated in-vitro 3D GCSC aggregate formation. WT1-AS overexpression exerted reverse effects. WT1-AS ameliorated the malignant phenotypes of GCSCs by down-regulating WT1 in vitro. WT1-AS inhibited tumor growth and metastasis, and reduced tumor stemness in GCSCs-derived (s.c., i.p., and i.v.) xenografts in vivo. Moreover, XBP1 was identified as an upstream regulator of WT1-AS in GCSCs. Also, 4 potential WT1-AS downstream targets (i.e. PSPH, GSTO2, FYN, and PHGDH) in GCSCs were identified. Additionally, CACNA2D1 was demonstrated to be a downstream target of the WT1-AS/ WT axis. XBP1 or CACNA2D1 knockdown exerted an adverse effect on the maintenance of stem cell-like behaviors and characteristics of GCSCs. In conclusion, WT1-AS weakened the stem celllike behaviors and characteristics of GCSCs in vitro and in vivo by down-regulating WT1. Investigations into the molecular mechanisms underlying the complex phenotypes of GCSCs might contribute to the better management of gastric cancer.