Background:

Identifying the genes and signaling pathways related to chemoresistance might facilitate the development of novel therapeutic strategies for colon cancer. In this study, we aimed to investigate the biological functions and underlying mechanisms of action of miR-19b and NR3C1, as well as their effects on chemosensitivity to oxaliplatin and prognosis of colon cancer patients.

Methods:

Reverse transcription–polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemical staining were used to analyze the expression of miR-19b and NR3C1. Dual firefly luciferase reporter gene analysis was used to identify miR-19b target genes. Associations of miR-19b and NR3C1 with survival were estimated by the Kaplan–Meier method and Cox regression analyses. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometric analysis were used to measure cell viability, cytotoxicity, cell cycle phase, and apoptosis, respectively. The effect of miR-19b on cell proliferation was investigated in vivo.

Results:

The miR-19b was overexpressed and NR3C1 was decreased in colon cancer tissue and cell lines (SW480 and DLD-1). The miR-19b inhibition and NR3C1 overexpression inhibited cell proliferation, and induced G1/S cell cycle blockade, apoptosis, and chemosensitivity to oxaliplatin in vitro. The miR-19b inhibition suppressed subcutaneous tumorigenesis in vivo. Increased miR-19b and decreased NR3C1 in colon cancer were correlated with poor prognosis. In addition, our results confirmed NR3C1 was directly targeted by miR-19b. Thus, miR-19b might inhibit apoptosis and enhance oxaliplatin chemoresistance via the PI3K/AKT/mTOR pathway.

Conclusions:

Our study revealed that miR-19b promotes cell survival and chemoresistance to oxaliplatin via the PI3K/AKT/mTOR pathway by downregulating NR3C1 in colon cancer. miR-19b and NR3C1 might be potential intervention targets for chemoresistance of colon cancer.

中文翻译：

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MicroRNA-19b通过PI3K / AKT / mTOR途径下调结肠癌中的NR3C1并增强奥沙利铂的化学耐药性。

背景：

鉴定与化学抗性有关的基因和信号通路可能促进结肠癌新治疗策略的发展。在这项研究中，我们旨在研究miR-19b和NR3C1的生物学功能和潜在作用机制，以及它们对奥沙利铂的化学敏感性和结肠癌患者预后的影响。

方法：

逆转录-聚合酶链反应（RT-PCR），蛋白质印迹和免疫组化染色被用于分析miR-19b和NR3C1的表达。使用萤火虫萤光素酶双重报告基因基因分析来鉴定miR-19b靶基因。通过Kaplan-Meier方法和Cox回归分析评估了miR-19b和NR3C1与存活率的关系。3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四唑溴化物（MTT）和流式细胞仪分析分别用于测量细胞活力，细胞毒性，细胞周期期和细胞凋亡。体内研究了miR-19b对细胞增殖的影响。

结果：

在结肠癌组织和细胞系（SW480和DLD-1）中，miR-19b过表达，而NR3C1降低。miR-19b抑制和NR3C1过表达抑制细胞增殖，并在体外诱导G1 / S细胞周期阻滞，凋亡和对奥沙利铂的化学敏感性。miR-19b抑制抑制体内皮下肿瘤发生。结肠癌中miR-19b的升高和NR3C1的降低与不良预后相关。另外，我们的结果证实了NR3C1直接被miR-19b靶向。因此，miR-19b可能通过PI3K / AKT / mTOR途径抑制细胞凋亡并增强奥沙利铂的化学耐药性。

结论：

我们的研究表明，miR-19b通过下调结肠癌组织中的NR3C1，通过PI3K / AKT / mTOR途径促进细胞存活和对奥沙利铂的化学耐药性。miR-19b和NR3C1可能是结肠癌化学耐药性的潜在干预目标。