Rationale: Mesenchymal stem cells (MSCs) have been the focus of many studies because of their abilities to modulate immune responses, angiogenesis, and promote tumor growth and metastasis. Our previous work showed that gastric cancer MSCs (GCMSCs) promoted immune escape by secreting of IL-8, which induced programmed cell death ligand 1 (PD-L1) expression in GC cells. Mounting evidence has revealed that PD-L1 expression is related to intrinsic tumor cell properties. Here, we investigated whether GCMSCs maintained a pool of cancer stem cells (CSCs) through PD-L1 signaling and the specific underlying molecular mechanism./nMethods: Stem cell surface markers, aldehyde dehydrogenase (ALDH) activity, migration and sphere formation abilities were tested to evaluate the stemness of GC cells. PD-L1-expressing lentivirus and PD-L1 specific siRNA were used to analyze the effects of PD-L1 on GC cells stemness. Annexin V/PI double staining was used to assess apoptosis of GC cells induced by chemotherapy. Co-Immunoprecipitation (Co-IP) and Mass spectrometry were employed to determine the PD-L1 binding partner in GC cells. PD-L1^Negative and PD-L1^Positive cells were sorted by flow cytometry and used for limiting dilution assays to verify the effect of PD-L1 on tumorigenic ability in GC cells./nResults: The results showed that GCMSCs enhanced the CSC-like properties of GC cells through PD-L1, which led to the resistance of GC cells to chemotherapy. PD-L1 associated with CTCF to contribute to the stemness and self-renewal of GC cells. In vivo, PD-L1^Positive GC cells had greater stemness potential and tumorigenicity than PD-L1^Negative GC cells. The results also indicated that GC cells were heterogeneous, and that PD-L1 in GC cells had different reactivity to GCMSCs./nConclusions: Overall, our data indicated that GCMSCs enriched CSC-like cells in GC cells, which gives a new insight into the mechanism of GCMSCs prompting GC progression and provides a potential combined therapeutic target.

中文翻译：

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胃癌间充质干细胞调节PD-L1-CTCF增强癌症干细胞样特性和肿瘤发生

基本原理：间充质干细胞（MSC）由于具有调节免疫反应，血管生成，促进肿瘤生长和转移的能力，因此成为许多研究的重点。我们以前的工作表明，胃癌细胞MSC（GCMSC）通过分泌IL-8促进免疫逃逸，IL-8诱导了GC细胞中程序性细胞死亡配体1（PD-L1）的表达。越来越多的证据表明，PD-L1表达与肿瘤细胞固有特性有关。这里，我们调查是否GCMSCs维持癌症干细胞（CSC）通过PD-L1信令和特定底层分子mechanism./n池方法：测试了干细胞表面标记，醛脱氢酶（ALDH）活性，迁移和球形成能力，以评估GC细胞的干性。用PD-L1表达慢病毒和PD-L1特异性siRNA分析PD-L1对GC细胞干性的影响。Annexin V / PI双重染色用于评估化学疗法诱导的GC细胞凋亡。使用共免疫沉淀（Co-IP）和质谱法确定GC细胞中的PD-L1结合伴侣。PD-L1^的负和PD-L1^阳性细胞通过流式细胞术分选，并且用于有限稀释测定法来验证在GC cells./n致瘤能力的PD-L1的影响结果：结果表明，GCMSCs通过PD-L1增强了GC细胞的CSC样特性，从而导致了GC细胞对化疗的耐药性。与CTCF相关的PD-L1有助于GC细胞的干性和自我更新。在体内，PD-L1^阳性GC细胞比PD-L1^阴性GC细胞具有更大的潜能和致瘤性。结果还表明，GC细胞是异质的，并且GC细胞中的PD-L1对GCMSCs具有不同的反应性。/n结论：总体而言，我们的数据表明GCMSCs丰富了GC细胞中的CSC样细胞，这为我们提供了新的认识GCMSCs促进GC进展的机制，并提供了潜在的联合治疗靶点。