Hsa_circ_0010220 regulates miR-198/Syntaxin 6 axis to promote osteosarcoma progression

SNARE proteins: Core engines of membrane fusion in cancer

Vesicles are loaded with a variety of cargoes, including membrane proteins, secreted proteins, signaling molecules, and various enzymes, etc. Not surprisingly, vesicle transport is essential for proper cellular life activities including growth, division, movement and cellular communication. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediate membrane fusion of vesicles with their target compartments that is fundamental for cargo delivery. Recent studies have shown that multiple SNARE family members are aberrantly expressed in human cancers and actively contribute to malignant proliferation, invasion, metastasis, immune evasion and treatment resistance. Here, the localization and function of SNARE proteins in eukaryotic cells are firstly mapped. Then we summarize the expression and regulation of SNAREs in cancer, and describe their contribution to cancer progression and mechanisms, and finally we propose engineering botulinum toxin as a strategy to target SNAREs for cancer treatment.

Osteosarcoma in a ceRNET perspective

Osteosarcoma (OS) is the most prevalent and fatal type of bone tumor. It is characterized by great heterogeneity of genomic aberrations, mutated genes, and cell types contribution, making therapy and patients management particularly challenging. A unifying picture of molecular mechanisms underlying the disease could help to transform those challenges into opportunities.This review deeply explores the occurrence in OS of large-scale RNA regulatory networks, denominated "competing endogenous RNA network" (ceRNET), wherein different RNA biotypes, such as long non-coding RNAs, circular RNAs and mRNAs can functionally interact each other by competitively binding to shared microRNAs. Here, we discuss how the unbalancing of any network component can derail the entire circuit, driving OS onset and progression by impacting on cell proliferation, migration, invasion, tumor growth and metastasis, and even chemotherapeutic resistance, as distilled from many studies. Intriguingly, the aberrant expression of the networks components in OS cells can be triggered also by the surroundings, through cytokines and vesicles, with their bioactive cargo of proteins and non-coding RNAs, highlighting the relevance of tumor microenvironment. A comprehensive picture of RNA regulatory networks underlying OS could pave the way for the development of innovative RNA-targeted and RNA-based therapies and new diagnostic tools, also in the perspective of precision oncology.

Circ_0049271 targets the miR-1197/PTRF axis to attenuate the malignancy of osteosarcoma

BACKGROUND

Circular RNAs (circRNAs) perform key regulatory functions in osteosarcoma (OS) tumorigenesis. In this study, we aimed to explore the detailed action mechanisms of circ_0049271 in OS progression.

METHODS

Cell colony formation, cell counting kit-8, and transwell assays were performed to assess the proliferation and invasion of OS cells. Quantitative reverse transcription-polymerase chain reaction and western blotting were used to determine the expression levels of polymerase 1 and transcript release factor (PTRF), microRNA (miR)-1197, and circ_0049271 in OS cells. Furthermore, RNA immunoprecipitation and dual luciferase assays were conducted to explore the targeted relationships among PTRF, miR-1197, and circ_0049271. Finally, a tumor formation assay was conducted to determine the effects of circ_0049271 on in vivo tumor growth in mice.

RESULTS

High expression levels of miR-1197 and low levels of circ_0049271 and PTRF were observed in OS cells. circ _0049271 targeted miR-1197 to mediate PTRF expression. Moreover, the proliferation and invasion of OS cells were repressed by circ_0049271 or PTRF overexpression and increased by miR-1197 upregulation. Enforced circ_0049271 also impeded tumor growth in vivo. Upregulation of miR-1197 reversed the antitumor effects of circ_0049271 on OS progression in vitro; however, PTRF overexpression attenuated the cancer-promoting effects of miR-1197 on OS in vitro.

CONCLUSIONS

Our findings revealed that circ_0049271 targeted the miR-1197/PTRF axis to attenuate the malignancy of OS, suggesting a potential target for its clinical treatment.

Circ_0136666 aggravates osteosarcoma development through mediating miR-1244/CEP55 axis

Background

Accumulating articles demonstrate that circular RNAs play pivotal functions in tumorigenesis. However, the working mechanism of circ_0136666 in osteosarcoma (OS) progression remains to be further clarified.

Methods

Real time-quantitative polymerase chain reaction and western blot assay were applied to determine RNA and protein expression, respectively. Cell proliferation was assessed by 5-Ethynyl-2′-deoxyuridine assay and colony formation assay. Transwell assays were carried out to assess cell migration and invasion abilities. Flow cytometry was performed to analyze cell apoptosis. Cell glycolysis was evaluated by analyzing the uptake of glucose and the production of lactate using the corresponding kits. Dual-luciferase reporter assay and biotinylated RNA-pull down assay were performed to confirm the target interaction between microRNA-1244 (miR-1244) and circ_0136666 or centrosomal protein 55 (CEP55). Xenograft tumor model was utilized to explore the role of circ_0136666 in tumor growth in vivo.

Results

Circ_0136666 expression was prominently elevated in OS tissues and cell lines. Circ_0136666 absence restrained the proliferation, migration, invasion and glycolytic metabolism and promoted the apoptosis of OS cells. Circ_0136666 negatively regulated miR-1244 expression by binding to it in OS cells. MiR-1244 overexpression suppressed the malignant behaviors of OS cells. CEP55 was a target of miR-1244 in OS cells. Circ_0136666 positively regulated CEP55 expression partly by sequestering miR-1244 in OS cells. CEP55 overexpression largely reversed circ_0136666 silencing-mediated influences in OS cells. Circ_0136666 silencing significantly suppressed tumor growth in vivo.

Conclusion

Circ_0136666 silencing inhibited OS progression partly by targeting miR-1244/CEP55 signaling. Silencing circ_0136666 and CEP55 or restoring miR-1244 level might be a potential therapeutic strategy for OS.

Circular RNA_0078767 upregulates Kruppel-like factor 9 expression by targeting microRNA-889, thereby inhibiting the progression of osteosarcoma

Among kids and juveniles, osteosarcoma (OS) is a common bone malignancy. Circular RNAs (circs, circRNAs) play important roles in multiple malignancies including OS, yet circ_0078767ʹs biological functions in OS are far from well elucidated. This study is targeted at understanding circ_0078767ʹs biological functions in OS and its molecular mechanisms. This study confirmed that circ_0078767 expression was reduced in OS cell lines and tissues. Circ_0078767 overexpression remarkably inhibited OS cell growth, migration, invasion, epithelial-mesenchymal transition (EMT), and promoted apoptosis, whereas circ_0078767 knockdown resulted in the opposite effects. MicroRNA-889 (miR-889) was targeted and regulated by circ_0078767, and miR-889 could negatively modulate Kruppel-like factor 9 (KLF9) expression. Besides, circ_0078767 positively regulated KLF9 expression in OS cells via repressing miR-889. In conclusion, circ_0078767 enhances KLF9 expression by targeting miR-889 to inhibit OS progression.

The promising role and prognostic value of miR-198 in human diseases

The importance of microRNAs (miRNAs or miRs) has attracted more and more attention. MiRNA is an approximately 22-nucleotide, single-stranded, non-coding RNA molecule that affects the expression of downstream target genes. MiRNAs regulate the occurrence and development of human diseases. The objective of this article is to explore the abnormal expression of miR-198 in a variety of human diseases. The relationships between abnormally expressed miR-198 and clinicopathological characteristics are also summarized. Its roles in various diseases and potential molecular mechanisms include involvement in many biological processes, such as cell cycle regulation, proliferation, invasion, migration, apoptosis, and drug resistance. The potential value of miR-198 for disease diagnosis, treatment, and especially, prognosis, are discussed. More in-depth research on miRNA will support the conversion from basic research to clinical applications of this molecule.

Dexmedetomidine disrupts esophagus cancer tumorigenesis by modulating circ_0003340/miR-198/HMGA2 axis

More and more studies have focused on the regulatory role of circular RNAs (circRNAs) in various cancers. However, it is not clear how dexmedetomidine (DEX) affects esophagus cancer progression by affecting the expression of circRNAs. This study aimed to investigate the role of DEX in esophagus cancer and its underlying mechanism. Cell Counting Kit-8 assay and 5-ethynyl-2'-deoxyuridine assays were conducted to evaluate cell proliferation. Flow cytometry analysis and transwell assay were performed for cell apoptosis and invasion. The protein levels of cleaved caspase-3, matrix metallopeptidase 9, and high mobility group AT-hook 2 (HMGA2) were assessed by western blot assay. The expression levels of circ_0003340 and microRNA-198 (miR-198) were determined by quantitative real-time PCR. Dual-luciferase reporter assay was performed to verify the interaction between miR-198 and circ_0003340 or HMGA2. Murine xenograft model was established to investigate the role of circ_0003340 and DEX in vivo. DEX exerted antitumor effects in esophagus cancer cells. DEX hindered proliferation and invasion while inducing apoptosis of esophagus cancer cells, which was abolished by circ_0003340 elevation, HMGA2 overexpression, or miR-198 silencing. miR-198 directly interacted with circ_0003340 and HMGA2 in esophagus cancer cells. Moreover, knockdown of circ_0003340 could improve the anticancer role of DEX in vivo. DEX constrained cell carcinogenesis by regulating circ_0003340/miR-198/HMGA2 axis in esophagus cancer, providing an effective clinical implication for preventing the development of the esophagus cancer by the DEX.

Has_circ_0010220 regulates the miR-574-3p/IL-6 axis to increase doxorubicin resistance in osteosarcoma

Background

Osteosarcoma (OS) is the most common primary bone malignancy. It has an aggressive nature and produces drug resistance in diseased patients, which in turn causes obstacles in treating cancer with chemotherapy. The objective of our investigation was to analyze the function and hsa_circ_0010220 mechanism in doxorubicin (DOX) resistance to OS.

Methods

The hsa_circ_0010220, IL-6, and miR-574-3p levels in OS diseased tissues and cell resistance towards DOX drug were elucidated by qRT-PCR and Elisa assay. The DOX half-inhibitory concentration (IC50) was quantified by Cell Counting Kit-8. For this study, we used RNA pull-down, RNA immunoprecipitation, and a dual-luciferase reporter experiment to identify the proteins that interacted with has_circ_0010220, IL-6, and miR-574-3p in OS cells that have developed resistance towards DOX.

Results

The results indicated upregulated Hsa_circ_0010220 and IL-6 expression, However, DOX-resistant OS tissues and cells showed a downregulation of miR-574-3p. Reducing DOX resistance in vitro was achieved by silencing Has_circ_0010220. Further, by sponging miR-574-3p, increasing has_circ_0010220 boosted DOX resistance. However, miR-574-3p bound to IL-6 and inhibited DOX resistance. Additionally, it was discovered that hsa_circ_0010220 sponged miR-574-3p for upregulating IL-6 expression.

Conclusions

Hsa_circ_0010220 encouraged OS resistance to DOX by miR-574-3p/IL-6 axis regulation, suggesting its potency as a promising biomarker for treating OS.

Emerging role and function of miR-198 in human health and diseases

Ever since their discovery, microRNAs (miRNAs/miRs) have astonished us by the plethora of processes they regulate, and thus adding another dimension to the gene regulation. They have been implicated in several diseases affecting cardiovascular, neurodegenerative, hepatic, autoimmune and inflammatory functions. A primate specific exonic miRNA, miR-198 has been vastly studied during the past decade, and shown to have a critical role in wound healing. The aberrant expression of miR-198 was first reported in schizophrenia, linking it to neural development. Later, its dysregulation and tumor suppressive role was reported in hepatocellular carcinoma. However, this was just a beginning, and after which there was an explosion of reports linking miR-198 deregulation to cancers and other ailments. The first target to be identified for miR-198 was Cyclin T1 in monocytes affecting HIV1 replication. Depending on the type of cancer, miR-198 has been shown to function either as a tumor suppressor or an oncomir. Interestingly, miR-198 is not only known to regulate multiple targets and pathways, but also is itself regulated by several circular RNAs and long-non-coding RNAs, highlighting a complex regulatory network. This review highlights the currently understood mechanism and regulation of miR-198 in different diseases, and its possible diagnostic and therapeutic potential.

Dissecting the Role of Circular RNAs in Sarcomas with Emphasis on Osteosarcomas

Circular RNAs (circRNAs) are single-stranded RNAs generated from exons back-splicing from a single pre-mRNA, forming covalently closed loop structures which lack 5'-3'-polarity or polyadenylated tail. Ongoing research depicts that circRNAs play a pivotal role in tumorigenesis, tumor progression, metastatic potential and chemoresistance by regulating transcription, microRNA (miRNA) sponging, RNA-binding protein interactions, alternative splicing and to a lesser degree, protein coding. Sarcomas are rare malignant tumors stemming from mesenchymal cells. Due to their clinically insidious onset, they often present at advanced stage and their treatment may require aggressive chemotherapeutic or surgical options. This review is mainly focused on the regulatory functions of circRNAs on osteosarcoma progression and their potential role as biomarkers, an area which has prompted lately extensive research. The attributed oncogenic role of circRNAs on other mesenchymal tumors such as Kaposi Sarcoma (KS), Rhabdomyosarcoma (RMS) or Gastrointestinal Stromal Tumors (GISTs) is also described. The involvement of circRNAs on sarcoma oncogenesis and relevant emerging diagnostic, prognostic and therapeutic applications are expected to gain more research interest in the future.