Circular RNA Sequencing Identifies CircASAP1 as a Key Regulator in Hepatocellular Carcinoma Metastasis

Abstract

Background and Aims There is growing evidence that single‐stranded, circular RNA (circRNA) plays a key role in the development of certain cancers, including hepatocellular carcinoma (HCC). It is less clear, however, what role circRNA plays in HCC metastasis. Approach and Results In this study, through circRNA sequencing, we identified a circRNA: circASAP1 (a circRNA derived from exons 2 and 3 of the ASAP1 gene, hsa_circ_0085616), which is associated with pulmonary metastasis after curative resection in patients with HCC. CircASAP1 was overexpressed in HCC cell lines with high metastatic potential and in metastatic HCCs. In vitro, circASAP1 promoted cell proliferation, colony formation, migration, and invasion, and in vivo, it enhanced tumor growth and pulmonary metastasis. Mechanism studies showed that circASAP1 acts as a competing endogenous RNA for microRNA 326 (miR‐326) and microRNA 532‐5p (miR‐532‐5p), both of which are tumor suppressors in HCC. We found that mitogen‐activated protein kinase (MAPK) 1 and colony stimulating factor (CSF)‐1 were direct common targets for microRNA 326 (miR‐326) and microRNA 532‐5p (miR‐532‐5p), which were regulated by circASAP1. CircASAP1 promotes HCC cell proliferation and invasion by regulating miR‐326/miR‐532‐5p‐MAPK1 signaling and, furthermore, mediates tumor‐associated macrophage infiltration by regulating the miR‐326/miR‐532‐5p‐CSF‐1 pathway. Clinical HCC samples exhibited a positive correlation between circASAP1 expression and levels of CSF‐1, MAPK1, and CD68+ tumor‐associated macrophages, all of which were predictive of patient outcomes. Conclusion We identified circASAP1 as a key regulator of HCC metastasis that acts on miR‐326/miR‐532‐5p‐MAPK1/CSF‐1 signaling and serves as a prognostic predictor in patients with HCC.

CircRNA hsa_circ_0110102 Function as Anti-Oncogenic Gene in Hepatocellular Carcinoma Through Modulating miR-580-5p/CCL2 Pathway

“…CircRNAs have also shown potential effect to in uence the tumor microenvironment, Circular RNA CDR1as may play a speci c role in immune and stromal cell in ltration in tumor tissue, especially those of CD8 + T cells, activated NK cells, M2 macrophages [31]. Circular RNA CircASAP1 could mediates tumor-associated-macrophage in ltration by regulating the miR-326/miR-532-5p-CSF-1 pathway [9]. So, targeting circular RNA on the tumor microenvironment may be a potential direction in the future.…”

“…For example, CircBACH1 (hsa_circ_0061395) is signi cantly upregulated in HCC tissue andcircBACH1 knockdown suppresses the proliferation and increased apoptosis of HCC cells by regulating p27 repression via HuR [8]. CircASAP1 acts as a ceRNA for miR-326 and miR-532-5p to mediates tumor-associated-macrophage (TAM) in ltration [9]. As a consequence, emerging evidences support the critical roles of circRNA for HCC tumorigenesis and development.…”

CircRNA circ-0110102 Function as Anti-oncogenic Gene in Hepatocellular Carcinoma through Modulating miR-580-5p/CCL2 Pathway

“…Circular RNA CircASAP1 could mediates tumor-associated-macrophage in ltration by regulating the miR-326/miR-532-5p-CSF-1 pathway [14]. So, targeting circular RNA on the tumor microenvironment may be a potential direction in the future.…”

“…For example, CircBACH1 (hsa_circ_0061395) is signi cantly upregulated in HCC tissue and circBACH1 knockdown suppresses the proliferation and increased apoptosis of HCC cells by regulating p27 repression via HuR [13]. CircASAP1 acts as a ceRNA for miR-326 and miR-532-5p to mediates tumor-associated-macrophage (TAM) in ltration [14]. As a consequence, emerging evidences support the critical roles of circRNA for HCC tumorigenesis and development.…”

circ_0084927 promotes cervical carcinogenesis by sponging miR-1179 that suppresses CDK2, a cell cycle-related gene

“…These RNAs perform a variety of biological functions, such as regulating genes. In recent years, a growing number of studies have shown that circRNAs are inextricably linked to the malignant process of many cancers [12][13][14][15][16]. Some researchers con rmed that circRNAs could promote CC [17][18][19], while some suggested that multiple circRNAs were associated with the pathological process of CC [20][21][22].…”