Department of Colorectal and Anal Surgery, The First Hospital of Jilin University, No. 71, Xinmin Street, Changchun, 130021, Jilin, People's Republic of China.
BMC Cancer. 2021 Apr 1;21(1):349. doi: 10.1186/s12885-021-08063-5.
Immunotherapy has been recently established as a new direction for the treatment of colorectal cancer (CRC), a gastrointestinal cancer. In this investigation, we aimed to expound how the posttranscriptional regulation modulated by microRNA-222 (miR-222) from mesenchymal stem cells-derived extracellular vesicles (MSC-EVs) affected the AKT pathway and the immune escape in CRC.
CRC cell malignant phenotype, including proliferation, migration, invasion, and apoptosis, was firstly detected after co-culture with MSC-EVs. miRNAs with differential changes in CRC cells before and after EVs treatment were filtered by microarray analysis. miR-222 was then downregulated to examine its role in CRC cells in response to EVs. Cells were implanted in mice to induce xenograft tumors, and infiltrating T cells was assessed by immunohistochemistry. The mRNA microarray was used to screen target genes, followed by rescue experiments. ChIP and western blot were conducted to validate the downstream biomolecule of ATF3.
After treatment of CRC cells with MSC-EVs, the expression of miR-222 was upregulated, and cell activity was increased. Inhibition of miR-222 decreased CRC malignant aggressiveness in vitro and reduced tumorigenesis and immune escape in vivo. miR-222 targeted and bound to ATF3. Downregulation of ATF3 enhanced CRC cell malignant aggressiveness, tumorigenic capacity and immune escape. Mechanistically, ATF3 inhibited AKT1 transcription and mediated the AKT pathway.
MSC-EVs carry miR-222 to promote CRC cell malignant aggressiveness and immune escape. miR-222 targets and binds to ATF3, which inhibits AKT1 transcriptional activity and thereby mediates the AKT pathway.
免疫疗法最近已被确立为胃肠道癌症——结直肠癌（CRC）的一种新的治疗方向。在本研究中，我们旨在阐述间充质干细胞衍生的细胞外囊泡（MSC-EVs）中的 microRNA-222（miR-222）通过转录后调控如何影响 AKT 通路和 CRC 中的免疫逃逸。
首先通过共培养 MSC-EVs 检测 CRC 细胞恶性表型，包括增殖、迁移、侵袭和凋亡。通过微阵列分析筛选 CRC 细胞在 EVs 处理前后差异变化的 miRNAs。然后下调 miR-222 以研究其在 CRC 细胞对 EVs 反应中的作用。将细胞植入小鼠以诱导异种移植肿瘤，并通过免疫组织化学评估浸润性 T 细胞。使用 mRNA 微阵列筛选靶基因，然后进行挽救实验。ChIP 和 Western blot 用于验证 ATF3 的下游生物分子。
用 MSC-EVs 处理 CRC 细胞后，miR-222 的表达上调，细胞活性增加。抑制 miR-222 可降低 CRC 细胞的体外恶性侵袭性，并减少体内肿瘤发生和免疫逃逸。miR-222 靶向并结合 ATF3。下调 ATF3 增强了 CRC 细胞的恶性侵袭性、致瘤能力和免疫逃逸。从机制上讲，ATF3 抑制 AKT1 转录并介导 AKT 通路。
MSC-EVs 携带 miR-222 促进 CRC 细胞的恶性侵袭性和免疫逃逸。miR-222 靶向并结合 ATF3，抑制 AKT1 转录活性，从而介导 AKT 通路。
