miR-582-5p Is Upregulated in Patients with Active Tuberculosis and Inhibits Apoptosis of Monocytes by Targeting FOXO1

Macrophage apoptosis is a host innate defense mechanism against tuberculosis (TB). In this study, we found that percentage of apoptotic cells in peripheral blood monocytes from patients with active TB was lower than that from healthy controls (p<0.001). To understand whether microRNAs can modulate apoptosis of monocytes, we investigated differentially expressed microRNAs in patients with active TB. miR-582-5p was mainly expressed in monocytes and was upregulated in patients with active TB. The apoptotic percentage of THP-1 cells transfected with miR-582-5p mimics was significantly lower than those transfected with negative control of microRNA mimics (p<0.001), suggesting that miR-582-5p could inhibit apoptosis of monocytes. To our knowledge, the role of miR-582-5p in regulating apoptosis of monocytes has not been reported so far. Systematic bioinformatics analysis indicated that FOXO1 might be a target gene for miR-582-5p and its 3′UTR contains potential binding sites for miR-582-5p. To determine whether miR-582-5p could influence FOXO1 expression, miR-582-5p mimics or negative control of microRNA mimics were transfected into THP-1 cells. RT-PCR and western blot analysis showed that the miR-582-5p could suppress both FOXO1 mRNA and protein expression. Co-transfection of miR-582-5p and FOXO1 3′UTR-luciferase reporter vector into cells demonstrated that significant decrease in luciferase activity was only found in reporter vector that contained a wild type sequence of FOXO1 3′UTR, suggesting that miR-582-5p could directly target FOXO1. In conclusion, miR-582-5p inhibited apoptosis of monocytes by down-regulating FOXO1 expression and might play an important role in regulating anti-M. tuberculosis directed immune responses.     

Circular RNA hsa_circ_0110389 promotes gastric cancer progression through upregulating SORT1 via sponging miR-127-5p and miR-136-5p

Increasing studies have found that circular RNAs (circRNAs) are aberrantly expressed and play important roles in the occurrence and development of human cancers. However, the function of circRNAs on environmental carcinogen-induced gastric cancer (GC) progression remains poorly elucidated. In the present study, hsa_circ_0110389 was identified as a novel upregulated circRNA in malignant-transformed GC cells through RNA-seq, and subsequent quantitative real-time PCR verified that hsa_circ_0110389 was significantly increased in GC tissues and cells. High hsa_circ_0110389 expression associates with advanced stages of GC and predicts poor prognosis. Knockdown and overexpression assays demonstrated that hsa_circ_0110389 regulates proliferation, migration, and invasion of GC cells in vitro. In addition, hsa_circ_0110389 was identified to sponge both miR-127-5p and miR-136-5p and SORT1 was validated as a direct target of miR-127-5p and miR-136-5p through multiple mechanism assays; moreover, hsa_circ_0110389 sponged miR-127-5p/miR-136-5p to upregulate SORT1 expression and hsa_circ_0110389 promoted GC progression through the miR-127-5p/miR-136-5p–SORT1 pathway. Finally, hsa_circ_0110389 knockdown suppressed GC growth in vivo. Taken together, our findings firstly identify the role of hsa_circ_0110389 in GC progression, which is through miR-127-5p/miR-136-5p–SORT1 pathway, and our study provides novel insight for the identification of diagnostic/prognostic biomarkers and therapeutic targets for GC.Subject terms: Gastrointestinal cancer, Non-coding RNAs     

microRNA-17-5p Modulates Bacille Calmette-Guerin Growth in RAW264.7 Cells by Targeting ULK1

To explore the potential roles of miRNAs in controlling the survival of mycobacteria in macrophages, miR-17-5p in the regulation of Bacillus Calmette-Guérin(BCG)growth in the macrophage RAW264.7 cells was interrogated. Our results reveal that an infection of BCG shows a time-dependent up-regulation of miR-17-5p in RAW264.7 cells in early phase; importantly, excessive expression of miR-17-5p in these cells exhibits an increased propagation of intracellular BCG. Mechanistically, the Unc-51 like autophagy activating kinase 1 (ULK1), an initial molecular of autophagy are identified as novel target of miR-17-5p, the miR-17-5p is capable of targeting down-regulating the expression of ULK1 protein. In addition, an overexpression of miR-17-5p in RAW264.7 cells is correlated with repression of ULK1 and the autophagosome related proteins LC3I/II. These results imply that miR-17-5p may be able to arrest the maturation of mycobacterial phagosomes in part by targeting ULK1, subsequently reduces the ability of host cells to kill intracellular BCG.     

Hsa_circ_0076931 suppresses malignant biological properties,down-regulates miR-6760-3p through direct binding,and up-regulates CCBE1 in glioma

The function of circular RNAs (circRNAs) in gliomas is as yet unknown. The present study explored role of hsa_circ_0076931 in glioma. circRNA expression profiles were identified via RNA-seq followed by qRT-PCR validation in three pairs of glioma and normal brain tissues (NBT). The function of hsa_circ_0076931 was investigated in vitro using cell lines as well as in vivo using a xenograft tumor. Hsa_circ_0076931 was up-regulated by overexpression and an mRNA profile compared with wild-type was identified by RNA-seq. The relationship between miR-6760-3p and hsa_circ_0076931 or CCBE1 was confirmed via luciferase reporter or AGO2-RIP assays. A total of 507 circRNAs were identified in glioma tissues that were differentially expressed compared with that in NBT, and the sequencing data were deposited in BioProject (ID: PRJNA746438). Hsa_circ_0007694 and hsa_circ_0008016 were memorably increased whereas hsa_circ_0076931 and hsa_circ_0076948 decreased in glioma compared with those in NBT. Additionally, hsa_circ_0076931 expression was negatively correlated with histological grade. Overexpression of hsa_circ_0076931 inhibited proliferation, migration, and invasion while promoting apoptosis of glioma cells. A total of 4383 and 537 aberrantly expressed genes were identified between the hsa_circ_0076931-overexpressed and control groups in H4 and U118-MG cells, respectively; the sequencing data were deposited in BioProject (ID: PRJNA746438). These differentially expressed genes were mainly enriched in cancer-related pathways. In addition, elevated hsa_circ_0076931 levels induced the expression of CCBE1 while suppressing miR-6760-3p expression. miR-6760-3p can bind to hsa_circ_0076931. The experimental evidence supports using hsa_circ_0076931 as a marker for glioma and to help prevent malignant progression. The mechanism might be relevant to miR-6760-3p and CCBE1.     

Hsa_circ_0003596 enhances the development of cell renal clear cell carcinoma through the miR-502-5p/IGF1/PI3K/AKT axis

Accumulating research findings have shown that circular RNAs (circRNAs) play an indispensable role in tumorigenesis and tumor progression. The current study aimed to explore the role and modulatory mechanism of hsa_circ_0003596 in clear cell renal cell carcinoma (ccRCC). Quantitative real-time polymerase chain reaction was adopted to detect the expression of hsa_circ_0003596 in ccRCC tissue and cell lines. 5-Ethynyl-2′-deoxyuridine, cell counting kit 8 and the colony formation assay were utilized to assess the proliferation potential of the ccRCC cells. Transwell along with wound healing assays were adopted to quantify infiltration coupled with the migration potential of the cells. The current research study found that the circRNA hsa_circ_0003596 was overexpressed in ccRCC tissue and cell lines. Further, result showed that hsa_circ_0003596 was associated with distant metastasis of renal cancer. Notably, the knockdown of hsa_circ_0003596 can lower the proliferation, infiltration and migration potential of ccRCC cells. The results of in vivo experiments found that the reduction of hsa_circ_0003596 significantly hampered the growth of tumors in mice. In addition, it was evident that hsa_circ_0003596 acts as a “molecular sponge” for miR-502-5p to upregulate the expression of the microRNA-502-5p (miR-502-5p) target insulin-like growth factor 1 (IGF1R). Furthermore, it was found that the phosphatidylinositol 3-kinase (PI3K)/AKT signaling was the downstream cascade of hsa_circ_0003596/miR-502-5p/IGF1R cascade, which is partly responsible for the cancer-promoting effect. Overall, the results of the present study showed that hsa_circ_0003596 facilitated the proliferation, infiltration and migration of ccRCC through the miR-502-5p/IGF1R/PI3K/AKT axis. Therefore, it was evident that hsa_circ_0003596 can serve as a possible biomarker and therapeutic target against ccRCC.     

Circular RNA hsa_circ_0000263 participates in cervical cancer development by regulating target gene of miR-150-5p

Circular RNA (circRNA) is a new class of noncoding RNA, and plays an important role in many pathological processes. Cervical cancer is the most common gynecologic malignant tumor. Recently, studies have shown that there is a variety of circRNA involved in the pathogenesis of cervical cancer. We screened out the highly expressed hsa_circ_0000263 from GSE102686 by the quantitative real-time polymerase chain reaction assay in cervical cancer cell lines. In this study, we investigated whether hsa_circ_0000263 might affect cell proliferation, migration, cell cycle and apoptosis in cervical cancer in vitro and in vivo. The luciferase reporter assay and RNA immunoprecipitation assay confirmed the direct interaction between miR-150-5p and hsa_circ_0000263. By using western blot and immunohistochemistry, we confirmed that hsa_circ_0000263 can regulate the expression of murine double minute 4 (MDM4) by affecting miR-150-5p, and finally affect the expression of p53 gene. We found that hsa_circ_0000263 was significantly upregulated in cervical cancer cells. In addition, the knockdown of hsa_circ_0000263, would inhibit cell proliferation and migration ability. In conclusion, our current research reveals the important role of hsa_circ_0000263/miR-150-5p/MDM4/p53 regulatory network in cervical cancer and provides a new insight into the pathogenesis of cervical cancer.     

Down-regulation of miR-20a-5p triggers cell apoptosis to facilitate mycobacterial clearance through targeting JNK2 in human macrophages

Induction of cell apoptosis is one of the major host defense mechanisms through which macrophages control Mycobacterium tuberculosis (Mtb) infection. However, the mechanisms underlying macrophage apoptosis triggered by Mtb infection are still largely unknown. In this study, a microarray profiling survey revealed 14 miRNAs were down-regulated in CD14+ monocytes from active pulmonary tuberculosis patients, and only the reduction of miR-20a-5p could be reversed after successful anti-tuberculosis treatment. Validation of miR-20a-5p expression was confirmed using real time qPCR. Moreover, miR-20a-5p expression also decreased in differentiated THP-1 macrophages after mycobacterial infection in vitro. Functional assays through forced or inhibited expression of miR-20a-5p in THP-1 macrophages demonstrated that miR-20a-5p functioned as a negative regulator of mycobacterial-triggered apoptosis. Importantly, inhibition of miR-20a-5p expression resulted in more efficient mycobacterial clearance from infected THP-1 macrophages while miR-20a-5p overexpression promoted mycobacterial survival. Mechanistically, miR-20a-5p was demonstrated to regulate Bim expression in a JNK2-dependent manner, unlike Bcl2, and luciferase assay showed JNK2 was a novel direct target of miR-20a-5p. Together, our findings indicate that downregulation of miR-20a-5p triggers macrophage apoptosis as a novel mechanism for host defense against mycobacterial infection.     

The mmu_circRNA_37492/hsa_circ_0012138 function as potential ceRNA to attenuate obstructive renal fibrosis

Circular RNAs (circRNAs) are involved in the pathogenesis of certain renal diseases, however, the function and mechanism of them in renal fibrosis remains largely unknown. In the present study, RNA expression data in unilateral ureteral obstruction (UUO) kidneys was obtained from our previous circRNA Microarray and public Gene Expression Omnibus datasets to construct a ceRNA network. The effects of target circRNA as long as the homologous human circRNA on renal fibrosis was examined in vitro and in vivo. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was further performed among genes regulated by the human circRNA. We found that circRNA_37492, showing well connection degree in the ceRNA network, was abundant expression and high sequence conservation. We observed that the expression of circRNA_37492 was induced by the TGF-β1 or UUO in BUMPT cells and C57BL/6 mice, respectively. In vitro, cytoplasmic circRNA_37492 inhibited type I, III collagen and fibronectin deposition by sponging miR-7682-3p and then upregulated its downstream target Fgb. In vivo, overexpression of circRNA_37492 attenuated fibrotic lesions in the kidneys of UUO mice via targeting miR-7682-3p/Fgb axis. Furthermore, hsa_circ_0012138, homologous with circRNA_37492, may potentially target miR-651-5p/FGB axis in human renal fibrosis. Not only that, GO and KEGG enrichment revealed that hsa_circ_0012138-regulated genes were previously demonstrated to related to the fibrosis. In conclusion, we for the first time demonstrated that circRNA_37492 attenuated renal fibrosis via targeting miR-7682-3p/Fgb axis, and the homologous hsa_circRNA_0012138 was speculated as a possible ceRNA to regulate multiple gene expressions and involve in human renal fibrosis, suggesting that circRNA_37492/hsa_circ_0012138 may serve as potent therapy target for obstructive renal fibrosis disease. Subject terms: End-stage renal disease, miRNAs     

Exosomal hsa_circ_0004658 derived from RBPJ overexpressed-macrophages inhibits hepatocellular carcinoma progression via miR-499b-5p/JAM3

Macrophage-derived exosomes (Mφ-Exo) have multidimensional involvement in tumor initiation, progression, and metastasis, but their regulation in hepatocellular carcinoma (HCC) is not fully understood. RBPJ has been implicated in macrophage activation and plasticity. In this study we assess the role of exosomes derived from RBPJ-overexpressed macrophages (RBPJ^+/+ Mφ-Exo) in HCC. The circular RNA (circRNA) profiles in RBPJ^+/+ Mφ-Exo and THP-1-like macrophages (WT Mφ)-Exo was evaluated using circRNA microarray. CCK-8, Transwell, and flow cytometry analyses were used to evaluate the function of Mφ-Exo-circRNA on HCC cells. Luciferase reporter assays, RNA immunoprecipitation, and Pearson’s correlation analysis were used to confirm interactions. A nude mouse xenograft model was used to further analyze the functional significance of Mφ-Exo-cirRNA in vivo. Our results shown that hsa_circ_0004658 is upregulated in RBPJ^+/+ Mφ-Exo compared to WT Mφ-Exo. RBPJ^+/+ Mφ-Exo and hsa_circ_0004658 inhibits proliferation and promotes apoptosis in HCC cells, whereas hsa_circ_0004658 knockdown stimulated cell proliferation and migration but restrained apoptosis in vitro and promotes tumor growth in vivo. The effects of RBPJ^+/+ Mφ-Exo on HCC cells can be reversed by the hsa_circ_0004658 knockdown. Mechanistic investigations revealed that hsa_circ_0004658 acts as a ceRNA of miR-499b-5p, resulting in the de-repression of JAM3. These results indicate that exosome circRNAs secreted from RBPJ^+/+ Mφ inhibits tumor progression through the hsa_circ_0004658/miR-499b-5p/JAM3 pathway and hsa_circ_0004658 may be a diagnostic biomarker and potential target for HCC therapy.Subject terms: Cancer stem cells, Liver cancer     

Circular RNA ubiquitin-associated protein 2 enhances autophagy and promotes colorectal cancer progression and metastasis via miR-582-5p/FOXO1 signaling

Numerous circular RNAs (circRNAs) have been identified as vital regulators in various cancers. The newly reported circular RNA ubiquitin-associated protein 2 (circUBAP2) is a critical player in cell growth and metastasis in various types of cancers, although its role in colorectal cancer (CRC) has yet to be fully elucidated. We find that circUBAP2 is upregulated in CRC tissues and cell lines to induce autophagy both in vitro and in vivo. The effects of circUBAP2 on migration, invasion, and proliferation may be partially related to autophagy. Mechanistically, we uncover that circUBAP2 can directly interact with miR-582-5p and subsequently act as a microRNA sponge to regulate the expression of the miR-582-5p target gene forkhead box protein O1 (FOXO1) and downstream signaling molecules, which collectively advance the progression and metastasis of CRC. These results suggest that circUBAP2 acts as an oncogene via a novel circUBAP2/miR-582-5p/FOXO1 axis, providing a potential biomarker and therapeutic target for CRC management.     

Lipotoxic hepatocytes promote nonalcoholic fatty liver disease progression by delivering microRNA-9-5p and activating macrophages

M1-polarized macrophages are involved in chronic inflammatory diseases, including nonalcoholic fatty liver disease (NAFLD). However, the mechanisms responsible for the activation of macrophages in NAFLD have not been fully elucidated. This study aimed at investigating the physiological mechanisms by which extracellular vesicles (EVs)-encapsulated microRNA-9-5p (miR-9-5p) derived from lipotoxic hepatocytes might activate macrophages in NALFD. After blood sample and cell collection, EVs were isolated and identified followed by co-culture with macrophages. Next, the palmitic acid-induced cell and high fat diet-induced mouse NALFD models were established to explore the in vitro and in vivo effects of EVs-loaded miR-9-5p on NAFLD as evidenced by inflammatory cell infiltration and inflammatory reactions in macrophages. Additionally, the targeting relationship between miR-9-5p and transglutaminase 2 (TGM2) was identified using dual-luciferase reporter gene assay. miR-9-5p was upregulated in the NAFLD-EVs, which promoted M1 polarization of THP-1 macrophages. Furthermore, miR-9-5p could target TGM2 to inhibit its expression. Downregulated miR-9-5p in NAFLD-EVs alleviated macrophage inflammation and M1 polarization as evidenced by reduced levels of macrophage inflammatory factors, positive rates of CD86⁺ CD11b⁺, and levels of macrophage surface markers in vitro. Moreover, the effect of silencing of miR-9-5p was replicated in vivo, supported by reductions in TG, TC, AST and ALT levels and attenuated pathological changes. Collectively, lipotoxic hepatocytes-derived EVs-loaded miR-9-5p downregulated the expression of TGM2 and facilitated M1 polarization of macrophages, thereby promoting the progression of NAFLD. This highlights a potential therapeutic target for treating NAFLD.     

Circular RNA hsa_circ_0043280 inhibits cervical cancer tumor growth and metastasis via miR-203a-3p/PAQR3 axis

Circular RNAs (circRNAs) are known to act as key regulators in a variety of malignancies. However, the role of circRNAs in cervical cancer (CCa) remains largely unknown. Herein, we demonstrated that a circRNA derived from the TADA2A gene (hsa_circ_0043280) was significantly downregulated in CCa and that this reduction in expression was correlated with a poor prognosis. Furthermore, our results demonstrated that hsa_circ_0043280 functions as a tumor suppressor to inhibit tumor growth and metastasis in CCa. Mechanistically, hsa_circ_0043280 competitively sponges miR-203a-3p and prevents miR-203a-3p from reducing the levels of PAQR3. Collectively, our results demonstrate that hsa_circ_0043280 plays a pivotal role in the development and metastasis of CCa, thus suggesting that hsa_circ_0043280 has significant potential as a prognostic biomarker and a therapeutic target for CCa.Subject terms: Prognostic markers, Cervical cancer     

Exosomal transfer of tumor-associated macrophage-derived hsa_circ_0001610 reduces radiosensitivity in endometrial cancer

The occurrence of radioresistance is a clinical obstacle to endometrial cancer (EC) treatment and induces tumor relapse. In this study, we found that tumor-associated macrophages (TAMs) enriched in EC specimens were determined to present an M2-like phenotype. In vitro, the coculture of M2-polarized macrophages significantly downregulated the radiosensitivity of EC cells by releasing exosomes. Hsa_circ_0001610 was found to be abundant in exosomes derived from M2-polarized macrophages (EXOs), and hsa_circ_0001610 knockdown eliminated the reduction effect of EXOs on the radiosensitivity of EC cells. The following mechanism research revealed that hsa_circ_0001610 functioned as the competing endogenous RNA of miR-139-5p, thereby upregulating cyclin B1 expression, which is a vital pusher of radioresistance in several types of cancer by regulating the cell cycle. Hsa_circ_0001610 overexpression reduced the radiosensitivity of EC cells, which was then reversed by miR-139-5p overexpression. In vivo, the promotion effect of EXOs on xenograft tumor growth in nude mice treated with irradiation was further reinforced after hsa_circ_0001610 overexpression. In conclusion, TAM-derived exosomes transferred hsa_circ_0001610 to EC cells, and the overexpressed hsa_circ_0001610 in EC cells released cyclin B1 expression through adsorbing miR-139-5p, thereby weakening the radiosensitivity of EC cells.Subject terms: Cancer, Cell biology     

Circular RNA hsa_circ_0001564 regulates osteosarcoma proliferation and apoptosis by acting miRNA sponge

Circular RNAs (circRNAs) is a novel type of non-coding RNAs generated from back splicing, which has been verified to mediate multiple tumorigenesis. However, the role of circRNA in osteosarcoma is still unclear. In the present study, we preliminarily screened the circRNAs expression profiles in osteosarcoma and investigated the potential regulation mechanism. The circRNAs expression profiles in osteosarcoma were screened using circRNA microarray analysis, and results showed that there were 1152 circRNAs up-regulated and 915 circRNAs down-regulated in tumor tissue compared to adjacent tissue. Hsa_circ_0001564, located at 5q35.3 and its associated-gene symbol is CANX, was one of the significantly overexpressed circRNAs in osteosarcoma tissue, as well as in osteosarcoma cell lines. In functional experiments, hsa_circ_001564 knockdown significantly suppressed the proliferation activity, induced cell cycle arrest in G0/G1 phase, and promoted apoptosis in HOS and MG-63 cells. Subsequently, we explored the probable mechanism of hsa_circ_001564, and fortunately, bioinformatics analysis revealed that miR-29c-3p contained the complementary binding region with hsa_circ_0001564, which was confirmed by dual-luciferase reporter assay. Moreover, rescue experiments illustrated that miR-29c-3p could reverse the oncogenesis effect of hsa_circ_001564. Our study discovers that hsa_circ_0001564 acts as miR-29c-3p sponge to mediate the tumorigenicity, which could act as a potential biomarker for the osteosarcoma and provide a novel insight for competing endogenous RNAs (ceRNAs) mechanism in osteosarcoma.     

Autophagy-associated circular RNA hsa_circ_0007813 modulates human bladder cancer progression via hsa-miR-361-3p/IGF2R regulation

Circular RNAs (circRNAs) drive several cellular processes including proliferation, survival, and differentiation. Here, we identified a circRNA hsa_circ_0007813, whose expression was upregulated in bladder cancer. High hsa_circ_0007813 expression was associated with larger tumor size, higher primary tumor T stage, and higher pathologic grade. Survival analysis showed that patients with high hsa_circ_0007813 expression levels had a poorer prognosis. Based on these findings from clinical tissue samples and cell lines, we assumed that hsa_circ_0007813 functioned a vital role in bladder cancer progression. Next, functional experiments revealed that knockdown of hsa_circ_0007813 inhibited proliferation, migration, and invasiveness of bladder cancer cells both in vitro and in vivo. Through extensive bioinformatic prediction and RNA pull-down assays, we identified hsa-miR-361-3p as a competing endogenous RNA of hsa_circ_0007813. Further bioinformatic studies narrowed targets to 35 possible downstream genes. We then found that knockdown of hsa_circ_0007813 led to altered cell autophagy, bringing our attention to IGF2R, one of the possible downstream genes. IGF2R was also known as cation-independent mannose-6-phosphate receptor (CI-M6PR), was discovered to participate in both autophagy and tumor biology. Regarding autophagy has a dominant role in the survival of tumor cells overcoming cellular stress and correlates with tumor progression, investigations were made to prove that hsa_circ_0007813 could regulate IGF2R expression via hsa-miR-361-3p sponging. The potential of hsa_circ_0007813 in regulating IGF2R expression explained its influence on cell behavior and clinical outcomes. Collectively, our data could offer new insight into the biology of circRNA in bladder cancer.Subject terms: Cancer metabolism, Bladder cancer, Macroautophagy, Cell growth, Cell invasion     

Circular RNA hsa_circ_101555 promotes hepatocellular carcinoma cell proliferation and migration by sponging miR-145-5p and regulating CDCA3 expression

Circular RNAs have been reported to play significant roles in regulating pathophysiological processes while also guiding clinical diagnosis and treatment of hepatocellular carcinoma (HCC). However, only a few circRNAs have been identified thus far. Herein, we investigated the role of a specific closed-loop structure of hsa_circ_101555 that was generated by back-splicing of the host gene casein kinase 1 gamma 1 (CSNK1G1) in the development and proliferation of HCC. We investigated the expression of Hsa_circ_101555 in HCC and normal tissues using bioinformatics. The expression level of hsa_circ_101555 was further detected by fluorescence in situ hybridization and qRT-PCR in ten HCC patients. Transwell, migration, WST-1 assays, and colony formation assays were used to evaluate the role of hsa_circ_101555 in HCC development and proliferation. The regulatory mechanisms of hsa_circ_101555 in miR-145-5p and CDCA3 were determined by dual luciferase reporter assay. A mouse xenograft model was also used to determine the effect of hsa_circ_101555 on HCC growth in vivo. hsa_circ_101555 showed greater stability than the linear RNA; while in vitro and in vivo results demonstrated that hsa_circ_101555 silencing significantly suppressed cell proliferation, migration, and invasion of HCC cells. Rescue experiments further demonstrated that suppression of miR-145-5p significantly attenuated the biological effects of hsa_circ_101555 knockdown in HCC cells. We also identified a putative oncogene CDCA3 as a potential miR-145-5p target. Thus, our results demonstrated that hsa_circ_101555 might function as a competing endogenous RNA of miR-145-5p to upregulate CDCA3 expression in HCC. These findings suggest that hsa_circ_101555 may be a potential therapeutic target for patients with HCC.Subject terms: Liver cancer, Long non-coding RNAs