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.     

c-Myc-induced circ-NOTCH1 promotes aggressive phenotypes of nasopharyngeal carcinoma cells by regulating the miR-34c-5p/c-Myc axis

Nasopharyngeal carcinoma (NPC) is the subclass of head and neck cancer with the highest incidence among otolaryngology malignancies. A growing amount of evidence has proven that circular RNAs (circRNAs) play key roles in the progression of multiple cancers. It has been reported that circ-NOTCH1 is a novel circRNA and functions as an oncogene in gastric cancer, while the regulatory mechanism of circ-NOTCH1 in NPC remains unknown. In the present research, our findings revealed that circ-NOTCH1 was overexpressed in NPC tissues and cells. Circ-NOTCH1 knockdown suppressed NPC cell proliferation, invasion, and migration. Subsequently, we discovered that c-Myc can activate circ-NOTCH1 by binding to the NOTCH1 promoter. c-Myc functioned as a tumor promoter in NPC cells. Mechanistically, circ-NOTCH1 served as a competitive endogenous RNA to modulate c-Myc expression by sponging miR-34c-5p. Additionally, overexpression of c-Myc reversed the circ-NOTCH1 knockdown-mediated inhibition of NPC cellular progression. Overall, this study suggested that c-Myc-induced circ-NOTCH1 promoted malignant phenotypes of NPC cells by regulating the miR-34c-5p/c-Myc axis.     

Circular RNA circ-VANGL1 as a competing endogenous RNA contributes to bladder cancer progression by regulating miR-605-3p/VANGL1 pathway

Increasing reports indicate that circular RNAs (circRNAs) are very important regulators in human diseases, including cancers. In bladder cancer (BC), several circRNAs have been reported to be involved in tumor progressions, such as circ-ITCH and circTCF25. However, the functions of most circRNAs in BC still remains largely unknown. In this study, we identified a novel circRNA termed as circ-VANGL1 by bioinformatics analysis. We found that circ-VANGL1 was highly expressed in BC tissues compared with adjacent normal tissues. Furthermore, we showed that circ-VANGL1 could serve as a prognostic marker for patients with BC. Through functional experiments, we found that circ-VANGL1 knockdown significantly suppressed BC cell proliferation, cell cycle, migration, and invasion in vitro. Besides, circ-VANGL1 silence inhibited BC cell propagation in vivo. Mechanistically, we identified circ-VANGL1 as a sponge of miR-605-3p which targeted VANGL1 in BC cells. Through repressing miR-605-3p availability, circ-VANGL1 contributes to VANGL1 expression, consequently leading to BC cell proliferation, migration, and invasion. Taken together, our study demonstrated circ-VANGL1/miR-605-3p/VANGL1 as a novel essential signaling pathway involved in BC progression.     

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     

CircRNA has_circ_0006427 suppresses the progression of lung adenocarcinoma by regulating miR-6783–3p/DKK1 axis and inactivating Wnt/β-catenin signaling pathway

Recently, circular RNAs (circRNAs) are identified as a novel class of noncoding RNAs playing important roles in human malignant tumors. However, the regulatory function of circRNA in lung adenocarcinoma (LUAD) is still largely unknown. Present study aimed to explore the role of circ_0006427 in LUAD progression. Firstly, the downregulation of circ_0006427 in LUAD tissues and cell lines was revealed by microarray analysis and qRT-PCR analysis. And we also confirmed the circ_0006427 as a prognostic target in LUAD patients. Functionally, overexpression of circ_0006427 effectively suppressed cell proliferation, migration and invasion. Mechanistically, circ_0006427 was found to be predominantly located in the cytoplasm of LUCA cell, and was further revealed to positively regulate DKK1 in LUAD by sponging miR-6783–3p. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis and western blot analysis revealed that circ_0006427 inactivated Wnt/β-catenin signaling pathway by upregulating DKK1. At last, rescue assays proved the function of circ_0006427/miR-6783–3p/DKK1 axis in LUAD progression. In conclusion, our study revealed that circ_0006427 suppressed lung adenocarcinoma progression through regulating miR-6783–3p/DKK1 axis.     

circ-ZEB1 regulates epithelial-mesenchymal transition and chemotherapy resistance of colorectal cancer through acting on miR-200c-5p

Circular RNAs (circRNAs) have been demonstrated to be important regulators in human malignant tumors, including colorectal cancer (CRC). While the role circ-ZEB1 played in CRC remains unclear. In this study, we aim to explore the biological function and the underlying mechanism of circ-ZEB1 in CRC. RNAscope was used to analyze the expression and localization of circ-ZEB1 in CRC tissues. Loss of function experiments were conducted, including CCK-8, transwell assays, flow cytometry analysis, and murine xenograft models, so as to detect the effect of circ-ZEB1 on CRC cells. IC50 assay was used to evaluate the influence of circ-ZEB1 on the chemoresistance of CRC cells. Epithelial-mesenchymal transition (EMT) related markers were detected. The relationship between circ-ZEB1 and miR-200c-5p was investigated by FISH, dual-luciferase reporter assay, and RIP assay. We found in our study that circ-ZEB1 was significantly upregulated in CRC tissues. Downregulation of circ-ZEB1 inhibited cell proliferation, colony formation, as well as cell migration and invasion abilities of CRC cell lines. In vivo experiments indicated that knockdown of circ-ZEB1 suppressed tumorigenesis and distant metastasis of CRC cells in nude mice. What's more, EMT and chemoresistance of CRC cells were also attenuated following circ-ZEB1 knockdown. Mechanistically, we proved that circ-ZEB1 could directly bind with miR-200c and functioned as miR-200c sponge to exert its biological functions in CRC cells. In conclusion, circ-ZEB1 could promote CRC cells progression, EMT, and chemoresistance via acting on miR-200c, elucidating a potential therapeutic target to inhibit CRC progression.     

Circular RNA circABCC4 as the ceRNA of miR‐1182 facilitates prostate cancer progression by promoting FOXP4 expression

In recent years, circular RNAs (circRNAs) have been identified to be essential regulators of various human cancers. However, knowledge of the functions of circRNAs in prostate cancer remains very limited. The correlation between circABCC4 and human cancer is largely unknown. This study aims to investigate the biological functions of circABCC4 in prostate cancer progression and illustrate the underlying mechanism. We found that circABCC4 was remarkably up‐regulated in prostate cancer tissues and cell lines and promoted FOXP4 expression by sponging miR‐1182 in prostate cancer cells. CircABCC4 knockdown markedly suppressed prostate cancer cell proliferation, cell‐cycle progression, migration and invasion in vitro. Furthermore, silencing of the circRNA also delayed tumor growth in vivo. Taken together, our findings indicated that circABCC4 facilitates the malignant behaviour of prostate cancer by promoting FOXP4 expression through sponging of miR‐1182. The circABCC4–miR‐1182‐FOXP4 regulatory loop may be a promising therapeutic target for prostate cancer intervention.     

miR-29c-3p Increases Cell Viability and Suppresses Apoptosis by Regulating the TNFAIP1/NF-κB Signaling Pathway via TNFAIP1 in Aβ-Treated Neuroblastoma Cells

Alzheimer’s disease (AD) is the most common cause of dementia among older people in worldwide. miR-29c-3p was reported to play a role in AD development. However, the detail function of miR-29c-3p in AD remains unclear. The aim of this research is to analyze the functional mechanism of miR-29c-3p in AD. The RNA levels of miR-29c-3p and Tumor necrosis factor-α-inducible protein-1 (TNFAIP1) were detected by Quantitative real time polymerase chain (qRT-PCR) reaction. Western blot assay was carried out to examine the protein levels of TNFAIP1, Bax, B-cell lymphoma-2 (Bcl-2), Cleaved caspase 3, and Nuclear factor-k-gene binding (NF-κB). The interaction between miR-29c-3p and TNFAIP1 was predicted by online tool TargrtScan and verified using the dual luciferase reporter assay and RNA immunoprecipitation RIP (RIP) assay. Besides, cell proliferation and apoptosis rate were determined by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry analysis, respectively. Aβ treatment decreased miR-29c-3p expression and increased TNFAIP1 expression. Overexpression of miR-29c-3p mitigated the effects of Aβ on proliferation and apoptosis. Similarly, knockdown of TNFAIP1 also reversed the effects of Aβ on cell progression. Interestingly, miR-29c-3p suppressed the expression of TNFAIP1 via binding to 3′UTR of TNFAIP1 mRNA. As expected, overexpression of TNFAIP1 reversed the effects of miR-29c-3p on Aβ-mediated cell progression. Besides, we also confirmed that miR-29c-3p affected Aβ-mediated cell progression by regulating TNFAIP1/NF-κB signaling pathway. In conclusion, our findings confirmed that miR-29c-3p attenuated Aβ-induced neurotoxicity through regulation of NF-κB signaling pathway by directly targeting TNFAIP1, providing the potential value for the treatment of AD patients.

     

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.     

CircBACH1 (hsa_circ_0061395) promotes hepatocellular carcinoma growth by regulating p27 repression via HuR

In recent years, an increasing number of circular RNAs (circRNAs) have been discovered in hepatocellular carcinoma (HCC). However, the functions of most circRNAs require further investigation. Here, we found that circBACH1 was significantly upregulated in HCC tissues and that high circBACH1 levels were closely associated with poor prognosis. In addition, circBACH1 could promote HCC growth by accelerating cell cycle progression in vitro and in vivo. We next investigated the cellular and molecular mechanisms and discovered that circBACH1 inhibited p27 translation, which influenced cell cycle progression. Moreover, we revealed that circBACH1 could combine directly with HuR using RNA immunoprecipitation assays, pull-down assays, and electrophoretic mobility shift assays. The combination of these molecules facilitated HuR translocation from the nucleus to the cytoplasm according to the fluorescence in situ hybridization and immunofluorescence results. Finally, silencing HuR abrogated circBACH1's inhibition of p27 translation and abolished the circBACH1-induced effect on HCC proliferation. In sum, circBACH1 plays a significant role as an oncogene through the circBACH1/HuR/p27 axis in HCC development.     

CircTIMELESS regulates the proliferation and invasion of lung squamous cell carcinoma cells via the miR-136-5p/ROCK1 axis

Numerous studies demonstrate that circular RNAs (circRNAs) are critical regulators of the occurrence and progression of tumors. However, research on the involvement of circRNAs in lung squamous cell carcinoma (LUSC) is limited. In our study, circTIMELESS (also named hsa_circ_0000408 in the Human circRNA Database) was upregulated in both LUSC tissues and LUSC cells, and circTIMELESS expression was positively associated with the TNM stage. Moreover, circTIMELESS silencing markedly suppressed invasion in vitro and disrupted proliferation in vitro as well as in vivo. Additional investigations have shown that circTIMELESS functions as a miR-136-5p “sponge” and regulates miR-136-5p expression. Furthermore, the impact of miR-136-5p upregulation was consistent with the results of circTIMELESS silencing, both of which inhibited the proliferation and invasion of LUSC cells. Additional results showed that Rho-associated coiled-coil containing protein kinase 1 (ROCK1) is targeted by miR-136-5p. The results of recovery experiments showed that ROCK1 overexpression partly rescued the impact of circTIMELESS silencing and miR-136-5p upregulation on proliferation and invasion. Consequently, our findings confirmed that circTIMELESS exists in LUSC and acts as a tumor promoter through the miR-136-5p/ROCK1 axis. Based on these findings, circTIMELESS may be potentially utilized as a therapeutic target for LUSC.     

Circular RNA TUBA1C accelerates the progression of non-small-cell lung cancer by sponging miR-143-3p

Non-small-cell lung cancer (NSCLC) is one of the most common solid tumors and the leading cause of lung cancer-related fatality. Growing evidence has indicated that circular RNAs (circRNAs) play important roles in the progression of multiple human cancers. As a novel circRNA, very little research has focused on the function of circRNA TUBA1C (circTUBA1C) in cancer development, including NSCLC. In the present study, we found that the expression of circTUBA1C was significantly upregulated in NSCLC tissues. The loss-of function assays suggested that circTUBA1C deficiency notably hampered cell proliferation as well as accelerated cell apoptosis in NSCLC. In mechanism, we discovered that circTUBA1C could act as a sponge for miR-143-3p and then negatively regulate miR-143-3p. Moreover, rescue assays demonstrated that knockdown of miR-143-3p could reverse circTUBA1C silence-mediated effects on cell proliferation and apoptosis. Besides, we established a xenografted tumor model to investigate the function of circTUBA1C in vivo. The result illustrated that the decline of tumor growth resulted from circTUBA1C deficiency could be recovered by miR-143-3p knockdown. Taken together, these findings indicated the important role of circTUBA1C/miR-143-3p axis in NSCLC, which may provide a potential target for NSCLC therapy.     

Circular RNA circPIP5K1A promotes non-small cell lung cancer proliferation and metastasis through miR-600/HIF-1α regulation

Circular RNAs (circRNAs) have an important function in human diseases, especially in cancer. circRNA hsa_circ_0014130 (circPIP5K1A), a particularly abundant circRNA, participates in the tumorigenesis of non-small cell lung cancer (NSCLC), although the underlying regulatory mechanism remains unclear. Here, we investigated the circPIP5K1A role in NSCLC. Expression of circPIP5K1A in NSCLC cell lines was explored with quantitative real-time PCR. The effect of circPIP5K1A on NSCLC was evaluated with circPIP5K1A silencing, miR-600 mimic transfection, and hypoxia-inducible factor (HIF)-1α overexpression, followed by assessment of cell proliferation, metastasis, and tumorigenesis in nude mice. The subcellular localization of circPIP5K1A was evaluated via fluorescence in situ hybridization (FISH), and correlation between circPIP5K1A, miR-600, and HIF-1α was assessed by luciferase assay. The data demonstrated that circPIP5K1A expression was increased in NSCLC cells. FISH showed that circPIP5K1A localized to the cytoplasm. The circPIP5K1A knockdown suppressed NSCLC cell metastasis and proliferation by promoting expression of miR-600. Overexpression of miR-600 inhibited HIF-1α-mediated metastasis and proliferation of NSCLC cell by downregulating the endothelial mesenchymal transition-related proteins, Snail and vimentin, and upregulating E-cadherin. In vivo experiments illustrated that circPIP5K1A silence suppressed tumor growth and pulmonary metastasis. The circPIP5K1A may function as an miR-600 sponge to facilitate NSCLC proliferation and metastasis by promoting HIF-1α. A bifluorescein reporter experiment confirmed that miR-600 was the circPIP5K1A target, and miR-600 interacted with the 3′ untranslated region of HIF-1α. These results show that circPIP5K1A acted as a tumor promoter through a novel circPIP5K1A/miR-600/HIF-1α axis, which provides candidate markers and therapeutic targets for NSCLC.     

Circ_0027599/PHDLA1 suppresses gastric cancer progression by sponging miR-101-3p.1

Background

Pleckstrin homology-like domain family A member 1 (PHLDA1) is a tumor suppressor gene in gastric cancer, but its role regulated by circular RNAs (circRNAs) is not known. CircRNAs are important regulators in cancer growth and progression, however, the molecular roles of circRNAs in gastric cancer are rarely known. The study was aimed to investigate the role of circRNAs in regulating PHLDA1 expression in gastric cancer.

Results

The circRNA expression profile in the gastric cancer tissues by circRNA microarray showed that hsa_circ_0027599 (circ_0027599) was significantly down-regulated in gastric cancer patients and cells when comparing with the controls. Circ_0027599 overexpression suppressed gastric cancer cell proliferation and metastasis. By using bioinformatics tools and luciferase reporter assays, circ_0027599 was verified as a sponge of miR-101-3p.1 (miR-101) and suppressed cancer cell survival and metastasis. It was also verified that PHLDA1 was regulated by circ_0027599 in gastric cancer cells.

Conclusions

The study uncovered that PHLDA1 was regulated by circ_0027599/miR-101, which suppressed gastric cancer survival and metastasis in gastric cancer.

     

The circular RNA circBCL2L1 regulates innate immune responses via microRNA-mediated downregulation of TRAF6 in teleost fish

Growing numbers of studies have shown that circular RNAs (circRNAs) can function as regulatory factors to regulate the innate immune response, cell proliferation, cell migration, and other important processes in mammals. However, the function and regulatory mechanism of circRNAs in lower vertebrates are still unclear. Here, we discovered a novel circRNA derived from the gene encoding Bcl-2-like protein 1 (BCL2L1) gene, named circBCL2L1, which was related to the innate immune responses in teleost fish. Results indicated that circBCL2L1 played essential roles in host antiviral immunity and antibacterial immunity. Our study also identified a microRNA, miR-30c-3-3p, which could inhibit the innate immune response by targeting inflammatory mediator TRAF6. And TRAF6 is a key signal transduction factor in innate immune response mediated by TLRs. Moreover, we also found that the antiviral and antibacterial effects inhibited by miR-30c-3-3p could be reversed with the expression of circBCL2L1. Our data revealed that circBCL2L1 functioned as a competing endogenous RNA (ceRNA) of TRAF6 by competing for binding with miR-30c-3-3p, leading to activation of the NF-κB/IRF3 inflammatory pathway and then enhancing the innate immune responses. Our results suggest that circRNAs can play an important role in the innate immune response of teleost fish.     

Long noncoding RNA Linc00339 promotes triple-negative breast cancer progression through miR-377-3p/HOXC6 signaling pathway

Recently, long noncoding RNAs (lncRNAs) have become the key gene regulators and prognostic biomarkers in various cancers. Through microarray data, Linc00339 was identified as a candidate oncogenic lncRNA. We compared the expression levels of Linc00339 in several breast cancer cell lines and normal mammary gland epithelial cell line. The effects of Linc00339 on tumor progression were examined both in vitro and in vivo. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays were applied to evaluate the functions of Linc00339, miR-377-3p, and HOXC6 on cell proliferation. Flow cytometry analysis was used to detect apoptosis and cell cycle distribution. Overall survival (OS) was analyzed using data from The Cancer Genome Atlas and molecular taxonomy of breast cancer international consortium (METABRIC). Dual luciferase assay and RNA immunoprecipitation were performed to confirm the interaction between Linc003339 and miR-377-3p. Linc00339 was increased in breast cancer cell lines compared with the normal epithelial cell. Through in vitro and in vivo experiments, Linc00339 overexpression promoted triple-negative breast cancer (TNBC) proliferation, inhibited cell cycle arrest, and suppressed apoptosis. Silencing of Linc00339 obtained the opposite effects. Mechanistic investigations demonstrated that Linc00339 could sponge miR-377-3p and regulate its expression. Higher expression of miR-377-3p indicated longer OS in breast cancer patients, especially in TNBC patients. Overexpression of miR-377-3p retarded TNBC cell growth through regulating cell cycle distribution and apoptosis. And miR-377-3p was involved in Linc00339-mediated TNBC proliferation through regulating HOXC6 expression. Knockdown of HOXC6 inhibited TNBC progression. In conclusion, our results illuminated that the novel Linc00339/miR-377-3p/HOXC6 axis played a critical role in TNBC progression and might be a promising therapeutic target for TNBC treatment.     

Tumor-derived exosomal circPSMA1 facilitates the tumorigenesis,metastasis, and migration in triple-negative breast cancer (TNBC) through miR-637/Akt1/β-catenin (cyclin D1) axis

Circular RNAs (circRNAs) are increasingly gaining importance and attention due to their diverse potential functions and their value as diagnostic biomarkers (disease specific). This study aims to explore the novel mechanisms by which exosome-contained circRNAs promote tumor development and metastasis in TNBC. We identified increased circRNA circPSMA1 in TNBC cells, their exosomes, and serum exosomes samples from TNBC patients. The overexpression of circPSMA1 promoted TNBC cell proliferation, migration, and metastasis both in vitro and in vivo. Moreover, we investigated the tumor-infiltrating immune cells (TICs) or stromal components in immune microenvironment (IME), and identified the significant differences in the immune cells between TNBC and non-TNBC samples. Mechanistically, circPSMA1 acted as a “miRNAs sponge” to absorb miR-637; miR-637 inhibited TNBC cell migration and metastasis by directly targeted Akt1, which recognized as a key immune-related gene and affected downstream genes β-catenin and cyclin D1. Subsequent co-culture experiments also demonstrated that exosomes from TNBC carrying large amounts of circPSMA1 could transmit migration and proliferation capacity to recipient cells. Kaplan–Meier plots showed that high expression of Akt1 and low expression of mir-637 are highly correlated with poor prognosis in patients with lymph node metastasis of TNBC. Collectively, all these results reveal that circPSMA1 functions as a tumor promoter through the circPSMA1/miR-637/Akt1-β-catenin (cyclin D1) regulatory axis, which can facilitate the tumorigenesis, metastasis, and immunosuppression of TNBC. Our research proposes a fresh perspective on novel potential biomarkers and immune treatment strategies for TNBC.Subject terms: Breast cancer, Cancer microenvironment     

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.