RORβ suppresses the stemness of gastric cancer cells by downregulating the activity of the Wnt signaling pathway

Abstract

Gastric cancer (GC) is the third leading cause of cancer-related mortality and the fifth most common type of cancer worldwide. GC stem cells (GCSCs) have been reported to be responsible for the malignant behavior of GC. However, the key molecular mechanism controlling GCSC function remains unclear. The present study aimed to investigate the function of retinoic acid-related orphan receptor β (RORβ) in GC. The expression levels of RORβ in GC cells and clinical GC tissues were analyzed using western blotting, reverse transcription-quantitative PCR (RT-qPCR) and immunohistochemistry. The association between RORβ expression levels and GCSC markers was analyzed using Gene Set Enrichment Analysis, and GeneChip was performed to identify differentially expressed genes between control and RORβ-overexpressing GC cells. CCK-8 and flow cytometric assays were used to evaluate the effect of RORβ on cell viability and apoptosis, respectively. The effect of RORβ on the self-renewal capacity of GCSCs was measured using a sphere formation assay, the expression levels of induced pluripotent stem (iPS) factors and epithelial-mesenchymal transition (EMT)-related factors were measured by RT-qPCR and western blotting, and the tumorigenic capacity was measured by an in vivo mouse model. Finally, the impact of RORβ on the Wnt signaling pathway was determined using western blotting and a TOP/FOP flash assay. The results revealed that the expression levels of RORβ were downregulated in GC tissues compared with para-carcinoma tissues, and were inversely associated with the expression levels of GCSC markers. The overexpression of RORβ upregulated the expression levels of the pro-apoptotic gene, Bcl-2 like protein 11, which subsequently inhibited the viability and promoted the apoptosis of GC cells. In addition, RORβ decreased the sphere forming ability, and downregulated the expression levels of iPS cell-and EMT-related factors. In vivo, RORβ suppressed the tumorigenic capacity and stemness of GC cells. Mechanistically, RORβ was revealed to decrease the activity of the Wnt/β-catenin signaling pathway in GCSCs. In conclusion, the findings of the present study identified RORβ as a novel suppressor of GCSCs and highlighted the prospect of RORβ as a novel candidate target for stem cell-based GC therapy.

Dysregulation of B7 family and its association with tumor microenvironment in uveal melanoma

“…CABP4 has been reported to be associated with the TME of urothelial carcinoma of the bladder currently (79). RORB can down-regulate the activity of Wnt signaling pathway, thus inhibiting the stemness of gastric cancer cells (82). RORB has also been found to be a prognostic marker of breast cancer (83).…”

HER2–CDH1 Interaction via Wnt/B-Catenin Is Associated with Patients’ Survival in HER2-Positive Metastatic Gastric Adenocarcinoma

“…Hyperactivation of canonical Wnt/β-catenin signaling has been reported in various cancer types including about 30–50% of GC [ 40 ], but, for the first time, we associated this pathway with the HER2-positive mGC subtype and its survival. Indeed, mounting evidence has suggested that overexpression of Wnt/β-catenin signaling not only affects gastric cell proliferation, but also the GC relapse and metastasis by giving rise to a new cancer population of stemness-associated self-renewal cells [ 41 , 42 ]. Furthermore, the self-renewal cell activity was found to increase in HER2-positive cancer stem cells via Wnt/β-catenin signaling [ 43 ] that had also been implicated in important tumor growth processes such as cell nutrient acquisition, cell metabolism, and immune response against the tumor cells [ 44 , 45 , 46 ].…”

Targeting Gastric Cancer Stem Cells to Enhance Treatment Response

“…Many other genes affect GCSCs through WNT, NOTCH, Hedgehog, and HIPPO signaling pathways, which we have summarized in Table 1 [ 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 ].…”