Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Life Sci. 2023 Jun 1;322:121646. doi: 10.1016/j.lfs.2023.121646. Epub 2023 Apr 1.
RN7SK (7SK), a highly conserved non-coding RNA, serves as a transcription regulator via interaction with a few proteins. Despite increasing evidences which support the cancer-promoting roles of 7SK-interacting proteins, limited reports address the direct link between 7SK and cancer. To test the hypothetic suppression of cancer by overexpression of 7SK, the effects of exosomal 7SK delivery on cancer phenotypes were studied.
Exosomes derived from human mesenchymal stem cells were loaded with 7SK (Exo-7SK). MDA-MB-231, triple negative breast cancer (TNBC), cell line was treated with Exo-7sk. Expression levels of 7SK were evaluated by qPCR. Cell viability was assessed via MTT and Annexin V/PI assays as well as qPCR assessment of apoptosis-regulating genes. Cell proliferation was evaluated by growth curve analysis, colony formation and cell cycle assays. Aggressiveness of TNBCs was evaluated via transwell migration and invasion assays and qPCR assessment of genes regulating epithelial to mesenchymal transition (EMT). Moreover, tumor formation ability was assessed using a nude mice xenograft model.
Treatment of MDA-MB-231 cells with Exo-7SK resulted in efficient overexpression of 7SK; reduced viability; altered transcription levels of apoptosis-regulating genes; reduced proliferation; reduced migration and invasion; altered transcription of EMT-regulating genes; and reduced in vivo tumor formation ability. Finally, Exo-7SK reduced mRNA levels of HMGA1, a 7SK interacting protein with master gene regulatory and cancer promoting roles, and its bioinformatically-selected cancer promoting target genes.
Altogether, as a proof of the concept, our findings suggest that exosomal delivery of 7SK may suppress cancer phenotypes via downregulation of HMGA1.
RN7SK（7SK）是一种高度保守的非编码 RNA，通过与几种蛋白质相互作用充当转录调节剂。尽管越来越多的证据支持 7SK 相互作用蛋白具有促进癌症的作用，但很少有报道涉及 7SK 与癌症之间的直接联系。为了测试通过过表达 7SK 抑制癌症的假设，研究了外泌体递送 7SK 对癌症表型的影响。
负载 7SK（Exo-7SK）的人间质干细胞衍生的外泌体。用 Exo-7sk 处理 MDA-MB-231、三阴性乳腺癌（TNBC）细胞系。通过 qPCR 评估 7SK 的表达水平。通过 MTT 和 Annexin V/PI 测定以及凋亡调节基因的 qPCR 评估来评估细胞活力。通过生长曲线分析、集落形成和细胞周期测定来评估细胞增殖。通过 Transwell 迁移和侵袭测定以及调节上皮间质转化（EMT）的基因的 qPCR 评估来评估 TNBC 的侵袭性。此外，使用裸鼠异种移植模型评估肿瘤形成能力。
用 Exo-7SK 处理 MDA-MB-231 细胞可有效过表达 7SK；降低活力；调节凋亡调节基因的转录水平；降低增殖；降低迁移和侵袭；调节 EMT 调节基因的转录；降低体内肿瘤形成能力。最后，Exo-7SK 降低了与 7SK 相互作用的 HMGA1 的 mRNA 水平，HMGA1 是一种具有主基因调节和促进癌症作用的 7SK 相互作用蛋白，以及其生物信息学选择的癌症促进靶基因。
总之，作为概念验证，我们的研究结果表明，通过下调 HMGA1，外泌体递送 7SK 可能抑制癌症表型。
