Extracellular vesicles (EVs) have received increasing attention for their role as possible regulators of cancer. miR-221-3p is a microRNA (miR) up-regulated in EVs secreted by drug-resistant A549-GR lung cancer cells. However, the underlying mechanism through which miR-221-3p-containing EVs regulate the progression of lung cancer remains elusive. Here, we attempted to reveal the mechanism by which miR-221-3p-containing EVs secreted by drug-resistant lung cancer cells regulate the functions of surrounding cells during the progression of lung cancer. A gemcitabine-sensitive lung cancer cell line was treated with isolated drug-resistant lung cancer EVs followed by an evaluation of the proliferation and migration of sensitive lung cancer cell lines and their resistance to gemcitabine treatment. Moreover, the miR-221-3p target gene HMBOX1 was identified by the Targetscan database while the progression of lung cancer was detected by knocking down miR-221-3p or overexpressing HMBOX1, or by treating sensitive cell lines with Akt/mTOR activator and inhibitor, respectively. Furthermore, an in vivo study was performed to validate the relationship between miR-221-3p and HMBOX1 and their roles in the progression of lung cancer. The proliferation and migration of sensitive lung cancer cell lines and their resistance to drugs were significantly enhanced after the treatment with drug-resistant EVs. Knockdown of miR-221-3p (in the EV of drug-resistant lung cancer or overexpression of HMBOX1 in sensitive lung cancer cell lines) reduced the transformation of sensitive lung cell lines, whereas, the treatment of sensitive lung cell lines with Akt/mTOR activator or inhibitor significantly affected the progression of lung cancer. In vivo experiments further confirmed that miR-221-3p released by drug-resistant lung cancer cells targeted the HMBOX1 to regulate the Akt/mTOR signaling pathway and affected the progression of lung cancer. We conclude that miR-221-3p-containing EVs secreted by drug-resistant lung cancer cells can potentially activate the Akt/mTOR signaling pathway by inhibiting HMBOX1, promoting the progression of lung cancer. The regulation of miR-221-3p represents a novel therapeutic target for the treatment of lung cancer.

细胞外囊泡 (EV) 因其作为可能的癌症调节剂的作用而受到越来越多的关注。miR-221-3p 是一种 microRNA (miR)，在耐药 A549-GR 肺癌细胞分泌的 EV 中上调。然而，含有 miR-221-3p 的 EV 调节肺癌进展的潜在机制仍然难以捉摸。在这里，我们试图揭示耐药肺癌细胞分泌的含有 miR-221-3p 的 EV 在肺癌进展过程中调节周围细胞功能的机制。用分离的耐药肺癌 EVs 处理对吉西他滨敏感的肺癌细胞系，然后评估敏感肺癌细胞系的增殖和迁移及其对吉西他滨治疗的耐药性。而且，miR-221-3p 靶基因 HMBOX1 由 Targetscan 数据库识别，而肺癌的进展通过敲除 miR-221-3p 或过表达 HMBOX1，或分别用 Akt/mTOR 激活剂和抑制剂处理敏感细胞系来检测. 此外，还进行了一项体内研究以验证 miR-221-3p 和 HMBOX1 之间的关系及其在肺癌进展中的作用。耐药性EVs治疗后，敏感肺癌细胞系的增殖和迁移及其对药物的耐药性显着增强。抑制 miR-221-3p（在耐药肺癌的 EV 中或敏感肺癌细胞系中 HMBOX1 的过表达）减少了敏感肺细胞系的转化，而，用 Akt/mTOR 激活剂或抑制剂处理敏感的肺细胞系显着影响肺癌的进展。体内实验进一步证实，耐药肺癌细胞释放的miR-221-3p靶向HMBOX1调控Akt/mTOR信号通路，影响肺癌的进展。我们得出结论，耐药肺癌细胞分泌的含有 miR-221-3p 的 EVs 可能通过抑制 HMBOX1 激活 Akt/mTOR 信号通路，促进肺癌的进展。miR-221-3p 的调控代表了治疗肺癌的新治疗靶点。体内实验进一步证实，耐药肺癌细胞释放的miR-221-3p靶向HMBOX1调控Akt/mTOR信号通路，影响肺癌的进展。我们得出结论，耐药肺癌细胞分泌的含有 miR-221-3p 的 EVs 可能通过抑制 HMBOX1 激活 Akt/mTOR 信号通路，促进肺癌的进展。miR-221-3p 的调控代表了治疗肺癌的新治疗靶点。体内实验进一步证实，耐药肺癌细胞释放的miR-221-3p靶向HMBOX1调控Akt/mTOR信号通路，影响肺癌的进展。我们得出结论，耐药肺癌细胞分泌的含有 miR-221-3p 的 EVs 可能通过抑制 HMBOX1 激活 Akt/mTOR 信号通路，促进肺癌的进展。miR-221-3p 的调控代表了治疗肺癌的新治疗靶点。