Tumor-suppressive circRHOBTB3 is excreted out of cells via exosome to sustain colorectal cancer cell fitness

Molecular Cancer

Fengyan Han¹  Xuan Lai¹  Kehong Ye¹  Siqin Lei¹  Minglang Mai¹  Hongfei Yu¹  Chaoyi Chen¹  Honghe Zhang²  Maode Lai³ 

[1]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), 310058, Hangzhou, China

[2]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), 310058, Hangzhou, China

[3]Key Laboratory of Disease Proteomics, 310058, Hangzhou, Zhejiang Province, China

[4]Cancer Center, Zhejiang University, 310058, Hangzhou, China

[5]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, 310058, Hangzhou, China

[6]Key Laboratory of Disease Proteomics, 310058, Hangzhou, Zhejiang Province, China

[7]Cancer Center, Zhejiang University, 310058, Hangzhou, China

[8]Department of Pharmacology, China Pharmaceutical University, 210009, Nanjing, China

关键词: Exosome;    Metastasis;    Colorectal cancer;    circRHOBTB3;    Circularization;   

DOI  :  10.1186/s12943-022-01511-1

来源: Springer

【 摘 要 】

Background & AimsTo clarify the biological roles, circularization process and secretion pathway of circRHOBTB3 in colorectal cancer (CRC) progression.MethodsWe 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.ResultscircRHOBTB3 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.ConclusionscircRHOBTB3 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.

【 授权许可】

CC BY