circ_NOTCH3 Functions as a Protooncogene Competing With miR-205-5p, Modulating KLF12 Expression and Promoting the Development and Progression of Basal-Like Breast Carcinoma

Circ_0007432 promotes non-small cell lung cancer progression and macrophage M2 polarization through SRSF1/KLF12 axis

Circular RNAs (circRNAs) plays critical roles in non-small cell lung cancer (NSCLC) development. Herein, we illustrated the effects of circ_0007432 on malignant features of NSCLC. We found that circ_0007432 played a promoting role in NSCLC progression, lying in accelerating cell viability, migration and invasion of NSCLC cells, promoting M2 macrophage polarization, suppressing cell apoptosis of NSCLC cells, and enhancing tumor growth in vivo. Mechanistically, the interactions among circ_0007432, SRSF1, KLF12, and IL-8 were validated by RNA-binding protein immunoprecipitation (RIP), electrophoretic mobility shift assay (EMSA), RNA pull-down, dual luciferase reporter assay and chromatin immunoprecipitation (ChIP) assays. Circ_0007432 upregulated KLF12 by recruiting SRSF1. KLF12 facilitated IL-8 expression and release by binding to IL-8 promoter. Furthermore, the role of circ_0007432/SRSF1/KLF12/IL-8 axis in malignant phenotypes of tumor cells or macrophage polarization was investigated using rescue experiments. In conclusion, circ_0007432 bound with SRSF1 to stabilize KLF12 and then promote IL-8 release, thus promoting malignant behaviors of NSCLC cells and M2 macrophage polarization.

CircRNA-CIRH1A Promotes the Development of Osteosarcoma by Regulating PI3K/AKT and JAK2/STAT3 Signaling Pathways

Osteogenic sarcoma (OS), one of the mesenchymal tumors with a high degree of malignancy, mainly occurs in the metaphysis of the long bones and around the knee joints in children and adolescents. The poor diagnosis in patients with OS can be attributed to the lack of early clinical symptoms, although the growth of tumor mass gradually results in severe pain and systemic symptoms. The mechanisms underlying the pathogenesis of OS are not fully understood. Thus, identifying early diagnostic biomarkers and novel targets involved in the progression of OS is of critical significance in the management of OS. CircRNA is a class of non-coding RNAs characterized by the close-loop structure and increased stability, which are implicated in the regulation of cell proliferation, differentiation, migration, and apoptosis. Moreover, circRNAs also play significant roles in aging and chronic disorders, such as cancer and cardiovascular diseases. Accordingly, we reported the upregulation of circRNA-CIRH1A in OS tissues and cell lines. Silencing circRNA-CIRH1A in OS cell lines (U2OS, HOS, Saos-2, and MG-63) could inhibit the cell proliferation, invasion, migration, and apoptosis, which was also validated in xenograft tumorigenesis mouse model. We further demonstrated that circRNA-CIRH1A sponged miR-1276, which subsequently disrupted the effect of miR-1276 on PI3K/AKT and JAK2/STAT3 signaling pathways. Together, our study revealed the oncogenic role of circRNA-CIRH1A in OS, and identified miR-1276/ PI3K-AKT and JAK2-STAT3 signaling axis as the key downstream mediators of circRNA-CIRH1A.

KLF12 promotes the proliferation of breast cancer cells by reducing the transcription of p21 in a p53-dependent and p53-independent manner

Breast cancer is the most common cancer affecting women worldwide. Many genes are involved in the development of breast cancer, including the Kruppel Like Factor 12 (KLF12) gene, which has been implicated in the development and progression of several cancers. However, the comprehensive regulatory network of KLF12 in breast cancer has not yet been fully elucidated. This study examined the role of KLF12 in breast cancer and its associated molecular mechanisms. KLF12 was found to promote the proliferation of breast cancer and inhibit apoptosis in response to genotoxic stress. Subsequent mechanistic studies showed that KLF12 inhibits the activity of the p53/p21 axis, specifically by interacting with p53 and affecting its protein stability via influencing the acetylation and ubiquitination of lysine370/372/373 at the C-terminus of p53. Furthermore, KLF12 disrupted the interaction between p53 and p300, thereby reducing the acetylation of p53 and stability. Meanwhile, KLF12 also inhibited the transcription of p21 independently of p53. These results suggest that KLF12 might have an important role in breast cancer and serve as a potential prognostic marker and therapeutic target.

Circular RNAs: New layer of complexity evading breast cancer heterogeneity

Advances in high-throughput sequencing techniques and bioinformatic analysis have refuted the "junk" RNA hypothesis that was claimed against non-coding RNAs (ncRNAs). Circular RNAs (circRNAs); a class of single-stranded covalently closed loop RNA molecules have recently emerged as stable epigenetic regulators. Although the exact regulatory role of circRNAs is still to be clarified, it has been proven that circRNAs could exert their functions by interacting with other ncRNAs or proteins in their own physiologically authentic environment, regulating multiple cellular signaling pathways and other classes of ncRNAs. CircRNAs have also been reported to exhibit a tissue-specific expression and have been associated with the malignant transformation process of several hematological and solid malignancies. Along this line of reasoning, this review aims to highlight the importance of circRNAs in Breast Cancer (BC), which is ranked as the most prevalent malignancy among females. Notwithstanding the substantial efforts to develop a suitable anticancer therapeutic regimen against the heterogenous BC, inter- and intra-tumoral heterogeneity have resulted in an arduous challenge for drug development research, which in turn necessitates the investigation of other markers to be therapeutically targeted. Herein, the potential of circRNAs as possible diagnostic and prognostic biomarkers have been highlighted together with their possible application as novel therapeutic targets.

Hsa_circ_NOTCH3 regulates ZNF146 through sponge adsorption of miR-875-5p to promote tumorigenesis of hepatocellular carcinoma

Background

To explore the specific mechanism of circular RNA (circRNA) in the occurrence and development of hepatocellular carcinoma (HCC), and provide new ideas for its diagnosis and treatment.

Methods

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was for evaluating the expression of circ_NOTCH3 in liver cancer tissues and matched normal tissues and related cell lines. After overexpression or co-expression of circ_NOTCH3 or microRNA (miRNA) in cells, the changes in cell function were analyzed. Bioinformatics analysis and dual luciferase report analysis were utilized to predict and verify the binding site between circ_NOTCH3 and miRNA. Western blotting was applied to detect gene expression alterations. Additionally, in vivo tumor growth was also utilized to further assess the influence of knocking-down circ_NOTCH3 on the progression of HCC.

Results

It was confirmed circ_NOTCH3 was highly expressed in HCC specimens and cells. The proliferation, migration, invasion, and oxaliplatin-resistance potential of HCC could be restrained by silencing circ_NOTCH3 or by ectopic expression of miR-875-5p in vitro. In terms of mechanism, circ_NOTCH3 directly binds to miR-875-5p, regulating its activity by targeting the 3'-UTR of ZNF146. Overexpression of circ_NOTCH3 evidently overturned the diminishing influence of miR-875-5p mimics on HCC cells.

Conclusions

As an oncogene, circ_NOTCH3 can trigger the proliferation, invasion, migration, and oxaliplatin resistance of HCC cells through the miR-875-5p/ZNF146 axis, and may be a promising target for the treatment of HCC.

circ_0000467 promotes the proliferation, metastasis, and angiogenesis in colorectal cancer cells through regulating KLF12 expression by sponging miR-4766-5p

Background

Circular RNAs have been identified as crucial players in the initiation and progression of cancers, including colorectal cancer (CRC). The Has_circ_0000467 (circ_0000467) expression has been found to be upregulated in CRC, but its function and mechanism remain unclear.

Methods

The expression levels of circ_0000467, microRNA-4766-5p (miR-4766-5p), and Krueppel-like factor 12 (KLF12) were examined using reverse transcription-quantitative polymerase chain reaction. Cell proliferation was analyzed by cell counting kit-8 assay and colony formation assay. The apoptosis was measured by flow cytometry. Transwell migration and invasion assays were applied to evaluate cell metastatic ability. Angiogenesis was detected using tube formation assay. All protein expressions were quantified by western blot assay. Dual-luciferase reporter assay was used to analyze intergenic binding. Xenograft models were constructed for the experiment of circ_0000467 in vivo.

Results

The expression of circ_0000467 was upregulated in CRC tissues and cells. Knockdown of circ_0000467 repressed cell proliferation, metastasis, and angiogenesis, but it induced apoptosis in CRC cells. circ_0000467 targeted miR-4766-5p and inhibited the expression of miR-4766-5p. Silencing of circ_0000467 inhibited CRC progression by upregulating miR-4766-5p. miR-4766-5p suppressed the expression of target gene KLF12 and KLF12 overexpression reversed the effects of miR-4766-5p on CRC cell behaviors. circ_0000467 positively regulated the expression of KLF12 by targeting miR-4766-5p. circ_0000467 downregulation in vivo reduced CRC tumorigenesis by regulating miR-4766-5p and KLF12.

Conclusion

circ_0000467 acted as an oncogene in CRC through regulating KLF12 expression by sponging miR-4766-5p. Therefore, circ_0000467 can be used as an effective target in CRC diagnosis and therapy.

circUSP34 accelerates osteosarcoma malignant progression by sponging miR-16-5p

Osteosarcoma (OS) is a primary and highly malignant mesenchymal tissue tumor. The specific pathological mechanism underlying disease initiation or progression remains unclear. Circular RNAs (circRNAs) are a type of covalently circular RNA with a head-to-tail junction site. In this study, we aimed to investigate the sponging mechanism between circRNAs and microRNAs (miRNAs) in OS. Based on the inhibited effect of miR-16-5p reported on OS, circUSP34 was analyzed as a sponge of miR-16-5p via Starbase. We found that circUSP34 promoted the proliferation, migration, and invasion of OS in vitro and in vivo. circUSP34 increased but miR-16-5p decreased in OS by qRT-PCR. Function assays showed that the malignancy of OS cells, including proliferation, migration, and invasion, was inhibited after knocking out circUSP34. Western blotting results showed that the expression level of vimentin and Ki-67 decreased. Similarly, miR-16-5p mimic compromised the proliferation, migration, and invasion of OS cells. FISH assay results indicated that circUSP34 and miR-16-5p were colocalized in the cytoplasm. The sponging mechanism of circUSP34 and miR-16-5p was verified by dual-luciferase reporter assay, RNA immunoprecipitation (RIP), and RNA pull down assays. Interestingly, the miR-16-5p inhibitor partly reversed the inhibitory effect of sh-circUSP34 on the malignancy of OS cells. Further, mice tumors for IHC indicated that vimentin, N-cadherin, and Ki-67 protein expression decreased, but E-cadherin protein expression increased. Collectively, circUSP34 promoted OS malignancy, including proliferation, migration, and invasion, by sponging miR-16-5p. It can serve as a potential therapeutic target and biomarker.

Circ-ACTR2 aggravates the high glucose-induced cell dysfunction of human renal mesangial cells through mediating the miR-205-5p/HMGA2 axis in diabetic nephropathy

BACKGROUND

Circular RNAs (circRNAs) have been considered as pivotal biomarkers in Diabetic nephropathy (DN). CircRNA ARP2 actin-related protein 2 homolog (circ-ACTR2) could promote the HG-induced cell injury in DN. However, how circ-ACTR2 acts in DN is still unclear. This study aimed to explore the molecular mechanism of circ-ACTR2 in DN progression, intending to provide support for the diagnostic and therapeutic potentials of circ-ACTR2 in DN.

METHODS

RNA expression analysis was conducted by the quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Cell growth was measured via Cell Counting Kit-8 and EdU assays. Inflammatory response was assessed by Enzyme-linked immunosorbent assay. The protein detection was performed via western blot. Oxidative stress was evaluated by the commercial kits. The molecular interaction was affirmed through dual-luciferase reporter and RNA immunoprecipitation assays.

RESULTS

Circ-ACTR2 level was upregulated in DN samples and high glucose (HG)-treated human renal mesangial cells (HRMCs). Silencing the circ-ACTR2 expression partly abolished the HG-induced cell proliferation, inflammation and extracellular matrix accumulation and oxidative stress in HRMCs. Circ-ACTR2 was confirmed as a sponge for miR-205-5p. Circ-ACTR2 regulated the effects of HG on HRMCs by targeting miR-205-5p. MiR-205-5p directly targeted high-mobility group AT-hook 2 (HMGA2), and HMGA2 downregulation also protected against cell injury in HG-treated HRMCs. HG-mediated cell dysfunction was repressed by miR-205-5p/HMGA2 axis. Moreover, circ-ACTR2 increased the expression of HMGA2 through the sponge effect on miR-205-5p in HG-treated HRMCs.

CONCLUSION

All data have manifested that circ-ACTR2 contributed to the HG-induced DN progression in HRMCs by the mediation of miR-205-5p/HMGA2 axis.