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.

中文翻译：

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RORβ通过下调Wnt信号通路的活性来抑制胃癌细胞的干性。

胃癌 (GC) 是癌症相关死亡的第三大原因，也是全球第五大最常见的癌症类型。据报道，GC 干细胞 (GCSC) 是导致 GC 恶性行为的原因。然而，控制GCSC功能的关键分子机制仍不清楚。本研究旨在研究视黄酸相关孤儿受体 β (RORβ) 在 GC 中的功能。使用蛋白质印迹、逆转录-定量 PCR (RT-qPCR) 和免疫组织化学分析 RORβ 在 GC 细胞和临床 GC 组织中的表达水平。使用基因集富集分析分析 RORβ 表达水平与 GCSC 标记之间的关联，并进行 GeneChip 以鉴定对照和 RORβ 过表达 GC 细胞之间的差异表达基因。CCK-8 和流式细胞术分别用于评估 RORβ 对细胞活力和细胞凋亡的影响。使用球形成试验测量 RORβ 对 GCSCs 自我更新能力的影响，通过 RT-qPCR 和蛋白质免疫学检测诱导多能干 (iPS) 因子和上皮间充质转化 (EMT) 相关因子的表达水平。印迹，并通过测量致瘤能力体内小鼠模型。最后，使用蛋白质印迹和 TOP/FOP 快速测定确定了 RORβ 对 Wnt 信号通路的影响。结果表明，与癌旁组织相比，胃癌组织中RORβ的表达水平下调，并与GCSC标志物的表达水平呈负相关。RORβ的过表达上调促凋亡基因Bcl-2样蛋白11的表达水平，随后抑制GC细胞的活力并促进其凋亡。此外，RORβ 降低球体形成能力，并下调 iPS 细胞和 EMT 相关因子的表达水平。体内，RORβ抑制GC细胞的致瘤能力和干细胞。从机制上讲，RORβ 会降低 GCSC 中 Wnt/β-catenin 信号通路的活性。总之，本研究的结果将 RORβ 确定为 GCSC 的新型抑制因子，并强调了 RORβ 作为基于干细胞的 GC 治疗的新型候选靶标的前景。