BACKGROUND Exosomes are essential for tumor growth, metastasis, and are used as novel signaling molecules in targeted therapies. Therefore, exosomal miRNAs can be used in new diagnostic and therapeutic approaches due to their involvement in the development of cancers. However, the detailed biological function, potential molecular mechanism and clinical application of exo-miR-15b-3p in gastric cancer (GC) remains unclear. METHODS miR-15b-3p mRNA levels in tissues, serum, cells and exosomes were analyzed using qRT-PCR assays. qRT-PCR, immunohistochemical and western blotting analyses were utilized for the determination of DYNLT1 expression. The interrelationship connecting miR-15b-3p with DYNLT1 was verified using Dual-luciferase report, western blotting and qRT-PCR assays. Fluorescent PKH-26 or GFP-Lv-CD63 labeled exosomes, as well as Cy3-miR-15b-3p, were utilized to determine the efficacy of the transfer of exo-miR-15b-3p between BGC-823 and recipient cells. Several in vitro assays and xenograft tumor models were conducted to determine exo-miR-15b-3p impact on GC progression. RESULTS This is the first study to confirm high miR-15b-3p expression in GC cell lines, tissues and serum. Exosomes obtained from 108 GC patient serum samples and GC cell-conditioned medium were found to show upregulation of exo-miR-15b-3p, with the area under the ROC curve (AUC) being 0.820 [0.763-0.876], which is superior to the AUC of tissues and serum miR-15b-3p (0.674 [0.600-0.748] and 0.642 [0.499-0.786], respectively). In addition, high exo-miR-15b-3p expression in serum was found to accurately predict worse overall survival. SGC-7901 and GES-1 cells are capable of internalizing BGC-823 cell-derived exosomes, allowing the transfer of miR-15b-3p. Migration, invasion, proliferation and inhibition of apoptosis in vitro and in vivo were enhanced by exo-miR-15b-3p, by restraining DYNLT1, Cleaved Caspase-9 and Caspase-3 expression. CONCLUSIONS This study identified a previously unknown regulatory pathway, exo-miR-15b-3p/DYNLT1/Caspase-3/Caspase-9, which promotes GC development and GES-1 cell malignant transformation. Therefore, serum exo-miR-15b-3p may be a potential GC diagnosis and prognosis biomarker, which can be used in precise targeted GC therapy.

中文翻译：

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miR-15b-3p的外体转移可通过DYNLT1 / Caspase-3 / Caspase-9信号通路增强胃癌的发生和恶性转化。

背景技术外泌体对于肿瘤生长，转移是必不可少的，并且在靶向疗法中用作新型信号分子。因此，由于外泌体miRNA参与了癌症的发展，因此可以用于新的诊断和治疗方法。但是，尚不清楚exo-miR-15b-3p在胃癌（GC）中的详细生物学功能，潜在的分子机制和临床应用。方法采用qRT-PCR方法分析组织，血清，细胞和外泌体中miR-15b-3p mRNA的水平。使用qRT-PCR，免疫组化和免疫印迹分析确定DYNLT1表达。miR-15b-3p与DYNLT1之间的相互关系已通过双重荧光素酶报告，蛋白质印迹和qRT-PCR分析进行了验证。荧光PKH-26或GFP-Lv-CD63标记的外泌体，以及Cy3-miR-15b-3p被用来确定exo-miR-15b-3p在BGC-823和受体细胞之间转移的功效。进行了几种体外测定和异种移植肿瘤模型，以确定exo-miR-15b-3p对GC进展的影响。结果这是第一个证实miR-15b-3p在GC细胞系，组织和血清中高表达的研究。发现从108名GC患者血清样品和GC细胞条件培养基中获得的外泌体显示exo-miR-15b-3p的上调，ROC曲线下的面积（AUC）为0.820 [0.763-0.876]，优于组织的AUC和血清miR-15b-3p（分别为0.674 [0.600-0.748]和0.642 [0.499-0.786]）。此外，发现血清中高exo-miR-15b-3p表达可准确预测较差的总生存期。SGC-7901和GES-1细胞能够内化BGC-823细胞衍生的外来体，从而可以转移miR-15b-3p。exo-miR-15b-3p通过抑制DYNLT1，Cleaved Caspase-9和Caspase-3的表达增强了其在体内外的迁移，侵袭，增殖和凋亡抑制作用。结论这项研究确定了一个以前未知的调控途径，exo-miR-15b-3p / DYNLT1 / Caspase-3 / Caspase-9，它可以促进GC的发展和GES-1细胞的恶性转化。因此，血清exo-miR-15b-3p可能是潜在的GC诊断和预后生物标志物，可用于精确的靶向GC治疗。Caspase-9和Caspase-3的表达减少。结论这项研究确定了一个以前未知的调控途径，exo-miR-15b-3p / DYNLT1 / Caspase-3 / Caspase-9，它可以促进GC的发展和GES-1细胞的恶性转化。因此，血清exo-miR-15b-3p可能是潜在的GC诊断和预后生物标志物，可用于精确的靶向GC治疗。Caspase-9和Caspase-3的表达减少。结论这项研究确定了一个以前未知的调控途径，exo-miR-15b-3p / DYNLT1 / Caspase-3 / Caspase-9，它可以促进GC的发展和GES-1细胞的恶性转化。因此，血清exo-miR-15b-3p可能是潜在的GC诊断和预后生物标志物，可用于精确的靶向GC治疗。