The increasing incidence of various cancers indicates the urgent need for finding accurate early diagnostic markers and more effective treatments for these malignancies. MicroRNAs (miRNAs) are small noncoding RNAs with great potentials to enter into cancer clinics as both diagnostic markers and therapeutic targets. miR-21 is elevated in many cancers, and promotes cell proliferation, metastasis, and drug resistance. In recent years, many studies have shown that targeting miR-21 combined with conventional chemotherapeutic agents could enhance their therapeutic efficacy, and overcome drug resistance and cancer recurrence both in vitro and in animal models. In this review, we first summarize the effects and importance of miR-21 in various cancers, and explore its function in drug resistance of cancer cells. Next, the challenges and prospects for clinical translation of anti-miR-21, as a therapeutic agent, will be discussed in combination cancer therapy.

中文翻译：

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miR-21：一种在联合癌症治疗中发挥重要作用的关键小分子

各种癌症发病率的增加表明迫切需要为这些恶性肿瘤找到准确的早期诊断标志物和更有效的治疗方法。MicroRNAs (miRNAs) 是小的非编码 RNA，具有作为诊断标志物和治疗靶点进入癌症临床的巨大潜力。miR-21 在许多癌症中升高，并促进细胞增殖、转移和耐药性。近年来，多项研究表明靶向miR-21联合常规化疗药物可提高其治疗效果，并在体外克服耐药性和癌症复发。在动物模型中。在这篇综述中，我们首先总结了miR-21在各种癌症中的作用和重要性，并探讨了它在癌细胞耐药中的作用。接下来，将讨论抗miR-21作为治疗剂在临床转化中的挑战和前景，将在联合癌症治疗中进行讨论。