Department of Pathology and Women's Hospital, Zhejiang University School of Medicine, Research Unit of Intelligence Classification of Tumor Pathology and Precision Therapy, Chinese Academy of Medical Sciences (2019RU042), Hangzhou, 310058, China.
Department of Pathology, Research Unit of Intelligence Classification of Tumor Pathology and Precision Therapy of Chinese Academy of Medical Sciences (2019RU042), Zhejiang University School of Medicine, Hangzhou, 310058, China.
Mol Cancer. 2022 Feb 11;21(1):46. doi: 10.1186/s12943-022-01511-1.
BACKGROUND & AIMS: To clarify the biological roles, circularization process and secretion pathway of circRHOBTB3 in colorectal cancer (CRC) progression.
We performed a comprehensive analysis of circRNA levels in serum exosomes from multiple types of cancer patients in public databases and verified the higher level of circRHOBTB3 in CRC sera versus healthy donors by RT-qPCR. Then, the function of circRHOBTB3 in CRC was investigated in vitro and in vivo. RNA-seq and RNA pull-down assays together with mass spectrometry identified the downstream signals and the binding proteins of circRHOBTB3. Finally, Antisense oligonucleotides (ASOs) were designed to target circularization and secretion elements of circRHOBTB3 for CRC therapy.
circRHOBTB3 levels were increased in the sera but was downregulated in tissue samples in CRC, and the downregulation was associated with poor prognosis. Furthermore, circRHOBTB3 acts a tumor-suppressive circRNA by repressing metabolic pathways, intracellular ROS production in CRC. Several key elements were discovered to regulate circRHOBTB3 circularization and exosomal secretion. Moreover, SNF8 was identified that sorts circRHOBTB3 into exosomes. Interestingly, we found that CRC cells could actively secrete more circRHOBTB3 than normal cells. According to the sequence of regulatory elements for circularization and exosomal secretion, we designed and synthesized ASOs, which increased circRHOBTB3 expression and blocked circRHOBTB3 exosomal secretion. More importantly, ASOs could inhibit CRC growth and metastasis in vitro and in vivo.
circRHOBTB3 plays a tumor-suppressive role in CRC and has to be excreted out of cells to sustain cancer cell fitness. ASOs targeting regulatory elements for circularization and exosomal secretion will become a novel antitumor strategy.
阐明环状 RNA（circRNA）RHOBTB3 在结直肠癌（CRC）进展中的生物学作用、环状化过程和分泌途径。
我们在公共数据库中对来自多种类型癌症患者的血清外泌体中的 circRNA 水平进行了全面分析，并通过 RT-qPCR 验证了 CRC 血清中 circRHOBTB3 水平高于健康供体。然后，在体外和体内研究了 circRHOBTB3 在 CRC 中的功能。RNA 测序和 RNA 下拉实验以及质谱分析鉴定了 circRHOBTB3 的下游信号和结合蛋白。最后，设计了反义寡核苷酸（ASO）来靶向 circRHOBTB3 的环状化和分泌元件，用于 CRC 治疗。
circRHOBTB3 水平在 CRC 患者的血清中升高，而在组织样本中降低，下调与预后不良相关。此外，circRHOBTB3 通过抑制 CRC 中的代谢途径和细胞内 ROS 产生，发挥肿瘤抑制 circRNA 的作用。发现了几个关键元素来调节 circRHOBTB3 的环状化和外泌体分泌。此外，鉴定到 SNF8 将 circRHOBTB3 分选到外泌体中。有趣的是，我们发现 CRC 细胞比正常细胞更能主动分泌更多的 circRHOBTB3。根据环状化和外泌体分泌的调节元件序列，我们设计并合成了 ASO，增加了 circRHOBTB3 的表达并阻断了 circRHOBTB3 的外泌体分泌。更重要的是，ASO 可以抑制 CRC 细胞在体外和体内的生长和转移。
circRHOBTB3 在 CRC 中发挥肿瘤抑制作用，并且必须从细胞中排出以维持癌细胞的适应性。靶向环状化和外泌体分泌的调节元件的 ASO 将成为一种新的抗肿瘤策略。
