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.     

Upregulation of hsa_circ_0136666 contributes to breast cancer progression by sponging miR-1299 and targeting CDK6

Circular RNAs (circRNAs) can participate in multiple cancers, including breast cancer. Increasing circRNAs are recognized in various cancers because of the high-throughput sequencing. However, the potential physiological effect of hsa_circ_0136666 in breast cancer progression is unknown. In our study, the biological role of hsa_circ_0136666 in breast cancer development was studied. It was displayed that hsa_circ_0136666 was greatly increased in breast cancer. In addition, overexpression of hsa_circ_0136666 was able to promote Michigan Cancer Foundation-7 (MCF7) and BT474 cell proliferation and triggered cell cycle in G2/M phase. microRNA plays critical role in tumor development and they can act as direct targets of circRNAs. miR-1299 has been implicated as a famous tumor suppressor in many cancers. Here, miR-1299 was predicted as the target of hsa_circ_0136666. Meanwhile, its Upregulation repressed breast cancer proliferation, migration and invasion capacity, which could be reversed by the increase of hsa_circ_0136666. Furthermore, Cyclin-dependent kinase 6 (CDK6) was speculated as the downstream target of miR-1299. In MCF7 and BT474 cells, CDK6 was greatly overexpressed and it was shown that CDK6 contributed a lot to breast cancer progression. Subsequently, it was implied that hsa_circ_0136666 could modulate CDK6 levels positively in vitro. In conclusion, it was revealed that Upregulation of hsa_circ_0136666 promoted breast cancer progression by sponging miR-1299 and targeting CDK6.     

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     

Circular RNA hsa_circ_0085131 is involved in cisplatin‐resistance of non‐small‐cell lung cancer cells by regulating autophagy

Non‐small‐cell lung carcinoma (NSCLC) continues to top the list of cancer mortalities worldwide. The role of circular RNAs (circRNAs) in tumorigenesis has been increasingly appreciated, although it is relatively unexplored in NSCLC. Herein, we reported the role of hsa_circ_0085131 in NSCLC. In the present study, NSCLC tumor specimens exhibited a higher hsa_circ_0085131 level in comparison to para‐tumor samples. And the higher level of hsa_circ_0085131 was associated with recurrence and poorer survival of NSCLC. Moreover, hsa_circ_0085131 promoted cell proliferation and cisplatin (DDP)‐resistance. Furthermore, hsa_circ_0085131 regulated cell DDP‐resistance by modulating autophagy. Hsa_circ_0085131 acted as a competing endogenous RNA of miR‐654‐5p to release autophagy‐associated factor ATG7 expression, thereby promoting cell chemoresistance. In conclusion, hsa_circ_0085131 enhances DDP‐resistance of NSCLC cells through sequestering miR‐654‐5p to upregulate ATG7, leading to cell autophagy. Therefore, these findings advocate targeting the hsa_circ_0085131/miR‐654‐5p/ATG7 axis as a potential therapeutic option for patients with NSCLC who are resistant to DDP.     

环状RNA：胃癌诊治的新星

环状RNA (circular RNA,circRNA)是一类闭合环状结构的RNA分子，广泛分布于各种组织中，它比线性RNA更稳定。circRNA分为外显子circRNA、外显子-内含子circRNA和内含子circRNA等3类。circRNA的主要功能为充当微RNA海绵、与RNA结合蛋白结合、翻译成蛋白质和调节转录等。近年来，大量研究表明，circRNA的异常表达在胃癌发生发展过程中起着至关重要的作用。circPTPN22、hsa＿circ＿0001772、circCYFIP2、hsa＿circ＿0017639和circPIP5K1A等的上调以及hsa＿circ＿002059、hsa＿circ＿0000190和circMTO1等的下调与胃癌的增殖和转移密切相关；而hsa＿circ＿0001313等影响胃癌细胞的顺铂耐药性。组织、血浆及外泌体中circPTPN22、hsa＿circ＿102958、hsa＿circ＿0141633、hsa＿circ＿0065149和hsa＿circ＿0026344等是胃癌新型诊断标志物；而hsa＿circ＿0005529、circ-RanGAP1、cir...     

Analysis of co-expression networks for circular RNAs and mRNAs reveals that circular RNAs hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 are candidate oncogenes in gastric cancer

Accumulating evidence has suggested that circular RNAs (circRNAs) play important roles in oncogenesis and tumor progression. However, our knowledge of circRNAs in gastric cancer (GC) remains limited. To investigate circRNAs involved in GC oncogenesis, we examined differentially-expressed circRNAs and mRNAs in GC tissues and paired noncancerous mucosa tissues using circRNA and mRNA microarrays. Next, we built gene co-expression networks according to the degree of correlation to predict the critical circRNAs in GC. Through bioinformatics analysis, we observed three newly identified circRNAs that are substantially upregulated in GC: hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15. Additionally, hsa_circ_0047905 and hsa_circ_0138960 positively correlated with their parental gene mRNA. Knockdown of hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 in GC cells, resulted in downregulation of parental gene expression. Functional assays suggested that inhibition of these three circular RNAs suppresses GC cell proliferation and invasion in vitro. Those findings suggest that hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 might act as tumor promoters in the pathogenesis of gastric cancer.     

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     

Genome‐Wide Analysis of circular RNAs and validation of hsa_circ_0006719 as a potential novel diagnostic biomarker in congenital scoliosis patients

Congenital scoliosis (CS) is a form of spinal curvature resulting from anomalous development of vertebrae. Recent studies demonstrated that circRNAs could serve as potential biomarkers of disease diagnosis. Genome‐wide circRNAs expression in seven CS patients and three healthy controls was initially detected. Bioinformatics analysis was conducted to explore the potential pathological pathway of CS. Quantitative PCR (qPCR) was performed to validate the selected circRNAs in the replication cohort with 32 CS patients and 30 healthy controls. Logistic regression controlling for gender was conducted to compare the expression difference. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic value. Twenty‐two differentially expressed circRNAs were filtered from genome‐wide circRNA sequencing. Seven circRNAs were validated by qPCR. Only hsa_circ_0006719 was confirmed to have a higher expression level in the CS group than the healthy control group (P = 0.036). Receiver operating characteristic curve also suggested that hsa_circ_0006719 had significant diagnostic value for CS (AUC = 0.739, P = 0.001). We described the first study of circRNAs in CS and validated hsa_circ_0006719 as a potential novel diagnostic biomarker of CS.     

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     

Hsa_circ_0136666 promotes the proliferation and invasion of colorectal cancer through miR-136/SH2B1 axis

Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide. Currently, an increasing evidence showed that circular RNAs (circRNAs) play important roles in tumor progression. However, the effects and underlying mechanisms of circRNAs in CRC progression remain unclear. In the present study, through circRNA high-throughput sequencing and quantitative real-time polymerase chain reaction, we identified that hsa_circ_0136666 was significantly overexpressed in CRC tissues and cell lines. High hsa_circ_0136666 expression was associated with poor overall survival of patients with CRC. In vitro function assays showed that hsa_circ_0136666 inhibition suppressed CRC cell proliferation, migration, invasion, and arrested CRC cells in the G0/G1 phase. Furthermore, we showed that hsa_circ_0136666 inhibition reduced CRC cell growth in vivo. Mechanistically, we revealed that hsa_circ_0136666 could increase SH2B1 expression via competitively binding miR-136 in CRC cells. In addition, SH2B1 overexpression could reverse the effects of hsa_circ_0136666 inhibition on CRC cell progression. In conclusion, our data suggested that hsa_circ_0136666 could promote CRC cell progression via the miR-136/SH2B1 axis, elucidating a novel approach to improve the effectiveness of CRC treatment.     

Hsa_circ_0001495 contributes to cervical cancer progression by targeting miR-526b-3p/TMBIM6/mTOR axis

Cervical cancer (CC) is a common gynecological malignant tumor, causing poor survival rate. Circular RNAs (circRNAs) are abundantly expressed in CC with their stable loop structure. However, the underlying mechanism and biological function of circRNAs remained unclear. Using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay, we measured the expression of hsa_circ_0001495, miR-526b-3p, and transmembrane Bax inhibitor motif containing 6 (TMBIM6) in CC tissues and cells. The relationship between miR-526b-3p and hsa_circ_0001495 or TMBIM6 was investigated by bioinformatics analysis, dual-luciferase and RIP analysis. Enzyme linked immunosorbent assay (ELISA) was conducted to evaluate glucose consumption and lactate production. 5-ethynyl-2′-deoxyuridine (EDU) assay were used to test cell proliferation. Cell apoptosis was analyzed by using flow cytometry assay. Transwell and wound-healing assays were used to measure cell invasion and migration. The expression of proteins was examined by western blot. Xenograft assay was applied to detect the effect of hsa_circ_0001495 in vivo. Our finding showed that hsa_circ_0001495 and TMBIM6 expression were upregulated, while miR-526b-3p was downregulated in CC tissues and cell lines. Hsa_circ_0001495 knockdown or TMBIM6 knockdown suppressed cell proliferation, migration, glycolysis, while promoted cell apoptosis in vitro, and hsa_circ_0001495 silence curbed tumor growth in vivo. Beside, hsa_circ_0001495 exerted its function in CC by positively regulating TMBIM6. Furthermore, hsa_circ_0001495 acted as a sponge for miR-526b-3p to regulate TMBIM6 expression. Hsa_circ_0001495/miR-526b-3p/TMBIM6 axis also regulated the phosphorylation of mammalian target of rapamycin (mTOR) in CC cells. In summary, hsa_circ_0001495 regulated the progression of CC by regulating miR-526b-3p/TMBIM6/mTOR pathway.     

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_0007456 regulates the natural killer cell-mediated cytotoxicity toward hepatocellular carcinoma via the miR-6852-3p/ICAM-1 axis

Circular RNAs (circRNAs) is one type of important non-coding RNAs that participate in tumorigenesis and cancer progression. In our previous study, we performed a microarray analysis of circRNAs between the tumor tissues and the adjacent normal tissues of hepatocellular carcinoma (HCC) patients, and found that the circRNA hsa_circ_0007456 is significantly downregulated in the tumor tissues and correlated with the prognosis of HCC. We further investigated the relationship between the expression levels of hsa_circ_0007456 in HCC and the susceptibility of NK cells, and found that the expression levels of hsa_circ_0007456 in HCC cell lines significantly influenced their susceptibility to NK cells. Through a series of screening and validation, we found that hsa_circ_0007456 mainly functioned through sponging miR-6852-3p and regulating the expression of intercellular adhesion molecule-1 (ICAM-1) in HCC. The miR-6852-3p/ICAM-1 axis is essential for the NK cytotoxicity toward HCC mediated by hsa_circ_0007456. In conclusion, we identify here hsa_circ_0007456 as a promising biomarker of HCC, and highlight hsa_circ_0007456/miR-6852-3p/ICAM-1 axis as an important signaling pathway in the process of tumor immune evasion and the tumorigenesis of HCC.Subject terms: Tumour biomarkers, Liver cancer     

Identification of novel dysregulated circular RNAs in early-stage breast cancer

Breast cancer is a major cause of cancer-related death in women worldwide. Non-coding RNAs are a potential resource to be used as an early diagnostic biomarker for breast cancer. Circular RNAs are a recently identified group of non-coding RNA with a significant role in disease development with potential utility in diagnosis/prognosis in cancer. In this study, we identified 26 differentially expressed circular RNAs associated with early-stage breast cancer. RNA sequencing and two circRNA detection tools (find_circ and DCC) were used to understand the circRNA expression signature in breast cancer. We identified hsa_circ_0006743 (circJMJD1C) and hsa_circ_0002496 (circAPPBP1) to be significantly up-regulated in early-stage breast cancer tissues. Co-expression analysis identified four pairs of circRNA-miRNA (hsa_circ_0023990 : hsa-miR-548b-3p, hsa_circ_0016601 : hsa_miR-1246, hsa_circ_0001946 : hsa-miR-1299 and hsa_circ_0000117:hsa-miR-502-5p) having potential interaction. The miRNA target prediction and network analysis revealed mRNA possibly regulated by circRNAs. We have thus identified circRNAs of diagnostic implications in breast cancer and also observed circRNA-miRNA interaction which could be involved in breast cancer development.     

Hsa_circ_0110757 upregulates ITGA1 to facilitate temozolomide resistance in glioma by suppressing hsa-miR-1298-5p

Temozolomide (TMZ) is the internationally recognized and preferred drug for glioma chemotherapy treatment. However, TMZ resistance in glioma appears after long-term use and is an urgent problem that needs to be solved. Circular RNAs (circRNAs) are noncoding RNAs and play an important role in the pathogenesis and progression of tumors. Hsa_circ_0110757 was identified in TMZ-resistant glioma cells by high-throughput sequencing analysis and was derived from reverse splicing of myeloid cell leukemia-1 (Mcl-1) exons. The role of hsa_circ_0110757 in TMZ-resistant glioma was evaluated both in vitro and in vivo. It was found that hsa_circ_0110757 and ITGA1 are more highly expressed in TMZ-resistant glioma than in TMZ-sensitive glioma. The overexpression of hsa_circ_0110757 in glioma patients treated with TMZ was obviously associated with tumor invasion. This study indicates that hsa_circ_0110757 inhibits glioma cell apoptosis by sponging hsa-miR-1298-5p to promote ITGA1 expression. Thus, hsa_circ_0110757/hsa-miR-1298-5p/ITGA could be a potential therapeutic target for reversing the resistance of glioma to TMZ.Subject terms: Chemotherapy, Tumour-suppressor proteins     

Circular RNA has_circ_0003204 inhibits oxLDL-induced vascular endothelial cell proliferation and angiogenesis

Circular RNAs (circRNAs) are widely expressed in eukaryotic cells and play a key role in atherosclerosis. The aim of this study is to explore the relationship between hsa_circ_0003204 and atherosclerosis. Here, hsa_circ_0003204 was aberrantly overexpressed in the ox-LDL-induced human umbilical vein endothelial cells (HUVECs). Knockdown of hsa_circ_0003204 facilitated the proliferation, migration, and invasion but reduced the apoptosis of oxLDL-induced HUVECs. Furthermore, hsa_circ_0003204 knockdown significantly reduced the E-cadherin expression but increased the expressions of N-cadherin and vimentin in oxLDL-induced HUVECs. Collectively, these findings suggest that hsa_circ_0003204 plays an important role in the proliferation and angiogenesis of HUVECs, providing a potential target for treating endothelial cell damage in atherosclerosis.