Hsa_circ_103973 Acts as a Sponge of miR-335 to Promote Cervical Cancer Progression

M6A-induced transcription factor IRF5 contributes to the progression of cervical cancer by upregulating PPP6C

Cervical cancer (CC) is a gynaecological malignancy tumour that seriously threatens women's health. Recent evidence has identified that interferon regulatory factor 5 (IRF5), a nucleoplasm shuttling protein, is a pivotal transcription factor regulating the growth and metastasis of various human tumours. This study aimed to investigate the function and molecular basis of IRF5 in CC development. IRF5, protein phosphatase 6 catalytic subunit (PPP6C) and methyltransferase-like 3 (METTL3) mRNA levels were evaluated by quantitative real-time (qRT)-polymerase chain reaction (PCR). IRF5, PPP6C, METTL3, B-cell lymphoma 2 and Bax protein levels were detected using western blot. Cell proliferation, migration, invasion, angiogenesis and apoptosis were determined by using colony formation, 5-ethynyl-2'-deoxyuridine (EdU), transwell, tube formation assay and flow cytometry assay, respectively. Glucose uptake and lactate production were measured using commercial kits. Xenograft tumour assay in vivo was used to explore the role of IRF5. After JASPAR predication, binding between IRF5 and PPP6C promoter was verified using chromatin immunoprecipitation and dual-luciferase reporter assays. Moreover, the interaction between METTL3 and IRF5 was verified using methylated RNA immunoprecipitation (MeRIP). IRF5, PPP6C and METTL3 were highly expressed in CC tissues and cells. IRF5 silencing significantly inhibited cell proliferation, migration, invasion, angiogenesis and glycolytic metabolism in CC cells, while induced cell apoptosis. Furthermore, the absence of IRF5 hindered tumour growth in vivo. At the molecular level, IRF5 might bind with PPP6C to positively regulate the expression of PPP6C mRNA. Meanwhile, IRF5 was identified as a downstream target of METTL3-mediated m6A modification. METTL3-mediated m6A modification of mRNA might promote CC malignant progression by regulating PPP6C, which might provide a promising therapeutic target for CC treatment.

Circular RNAs and cervical cancer: friends or foes? A landscape on circRNA-mediated regulation of key signaling pathways involved in the onset and progression of HPV-related cervical neoplasms

Cervical cancer (CC) is a common gynecologic malignancy, accounting for a significant proportion of women death worldwide. Human papillomavirus (HPV) infection is one of the major etiological causes leading to CC onset; however, genetic, and epigenetic factors are also responsible for disease expansion. Circular RNAs (circRNAs), which are known as a particular subset of non-coding RNA (ncRNA) superfamily, with covalently closed loop structures, have been reported to be involved in the progression of diverse diseases, especially neoplasms. In this framework, abnormally expressed circRNAs are in strong correlation with CC pathogenesis through regulating substantial signaling pathways. Also, these RNA molecules can be considered as promising biomarkers and therapeutic targets for CC diagnosis/prognosis and treatment, respectively. Herein, we first review key molecular mechanisms, including Wnt/β-catenin, MAPK, and PI3K/Akt/mTOR signaling pathways, as well as angiogenesis and metastasis, by which circRNAs interfere with CC development. Then, diagnostic, prognostic, and therapeutic potentials of these ncRNA molecules will be highlighted in depth.

Circular RNA ATP2C1 (has_circ_0005797) sponges miR-432/miR-335 to promote breast cancer progression through regulating CCND1 expression

Breast cancer (BC) is the most frequently diagnosed malignancy in the world. Accumulating evidence has indicated that circular RNAs (circRNAs) play essential roles in BC. Here we investigated the biological functions of circATP2C as a competing endogenous RNA (ceRNA) in BC development. We found that circATP2C1 expression was upregulated in BC cells and tissues and was significantly associated with the poor overall survival in BC patients. CircATP2C1 is more resistant to RNase R exonuclease and Actinomycin D than is the linear mRNA of ATP2C1. CircATP2C1-knockdown inhibited the viability, colony proliferation and invasion abilities, while increasing the apoptosis rates of BC cells in vitro, as well as inhibiting tumor mass, size and weight in vivo. Upregulation of miR-432 and miR-335 inhibited CCND1 expression in BC cells. Both miR-432/miR-335 specifically bind to the 3'-UTR of circATP2C1 and CCND1 (CyclinD1). The inhibition of the aggression of BC cells by circATP2C1-knockdown was rescued by co-transfection of miR-432/miR-335 inhibitors. In conclusion, circATP2C1 promotes BC oncogenesis and metastasis by sponging miR-432/miR-335 to abolish the inhibition of the target gene, CCND1. This study suggests that circATP2C1 has implications for BC diagnosis and treatment.

Circular RNA KIF4A Promotes Liver Metastasis of Breast Cancer by Reprogramming Glucose Metabolism

Background

Circular RNAs (circRNAs) regulate complex functional processes and play crucial roles in cancer development and progression. It was reported that circKIF4 regulates the progression of triple-negative breast cancer (TNBC). This study evaluates the role of circKIF4 in breast cancer distant metastasis and metabolic reprogramming.

Methods

RT-qPCR was performed to verify the expression of circKIF4A in breast cancer, liver metastatic tissues, and cell lines. The function of circKIF4A in metastasis was evaluated both in vitro and in vivo through a series of experiments, including cell migration and glucose intake experiments. Additionally, we conducted molecular experiments to clarify the regulatory role of circKIF4A. We then conducted a Luciferase reporter assay and an RNA immunoprecipitation assay to identify the molecular interactions between circKIF4A and miRNA.

Results

circKIF4A was overexpressed in breast cancer cell lines and tissues, inhibiting its expression and suppressing breast cancer growth and metastasis. Interestingly, we observed that circKIF4A reprogrammed the glucose metabolism of breast cancer, and silencing circKIF4A greatly affected glucose uptake and lactate production in breast cancer cells. miR-335 can be sponged by circKIF4A, which affected the expression of ALDOA/OCT4 protein and regulated HK2/PKM2 expression.

Conclusions

This study demonstrated that the circKIF4A-miR-335-OCT4/ALDOA-HK2/PKM2 axis is critical to breast cancer metabolic reprogramming, indicating that this axis could be a novel therapeutic target for the treatment of liver metastasis of breast cancer.

Knockdown of circHECTD1 inhibits oxygen-glucose deprivation and reperfusion induced endothelial-mesenchymal transition

Ischemic stroke (IS) has become a cerebrovascular disease which seriously threatens the elderly people. It has been reported that circRNAs participate in multiple diseases, including IS. However, the role of circHECTD1 in IS remains largely unknown. To mimic IS in vitro, human cerebral microvascular endothelial cells (HCMECs) were treated with oxygen glucose deprivation/reperfusion (OGD/R). Meanwhile, MCAO mouse model was established to detect the expression of circHECTD1 in IS. qRT-PCR and western blot were used to test gene and protein expressions, respectively. CCK-8 assay was used to investigate the cell viability. Moreover, cell migration and tube formation were assessed by transwell and tube formation assays. In addition, RIP and luciferase assay were performed to explore the association among circHECTD1, miR-335 and NOTCH2. CircHECTD1 was significantly upregulated in IS. OGD/R significantly induced EndoMT in HCMECs, while knockdown of circHECTD1 notably reversed this phenomenon. In addition, silencing of circHECTD1 remarkably reversed OGD/R-induced promotion of HCMEC tube formation and migration. Meanwhile, circHECTD1 upregulated the level of NOTCH2 through binding with miR-335. Furthermore, miR-335 inhibited the process of EndoMT in IS via targeting NOTCH2. In summary, circHECTD1 knockdown significantly alleviated EndoMT process in HCMECs via mediation of miR-335/NOTCH2 axis. Thus, circHECTD1 might act as a potential target against IS.

Hsa_circ_0074269-mediated Upregulation of TUFT1 Through miR-485-5p Increases Cisplatin Resistance in Cervical Cancer

Most cervical cancer patients are prone to developing acquired cisplatin (DDP) resistance. Hsa_circ_0074269 (circ_0074269) plays a promoting role in cervical cancer, but whether circ_0074269 mediates cervical cancer resistance to DDP is unclear. Expression of circ_0074269 was detected by real-time quantitative polymerase chain reaction (RT-qPCR). The half-maximal inhibitory concentration (IC₅₀) value, viability, proliferation, colony formation, migration, and apoptosis of DDP-resistant cervical cancer cells were determined. The molecular mechanisms associated with circ_0074269 were predicted by bioinformatics analysis and confirmed by dual-luciferase reporter and RIP assays. Xenograft assay was conducted to validate the effect of circ_0074269 on DDP resistance in vivo. Exosomes were isolated by ultracentrifugation. Circ_0074269 was overexpressed in DDP-resistant cervical cancer samples and cells. Silencing of circ_0074269 elevated DDP sensitivity, repressed DDP-resistant cervical cancer cell proliferation, and induced DDP-resistant cervical cancer cell apoptosis in vivo and in vitro and curbed DDP-resistant cervical cancer cell migration in vitro. And circ_0074269 could regulate DDP resistance via regulating TUFT1 expression via sponging miR-485-5p. More strikingly, circ_0074269 was also overexpressed in exosomes from DDP-resistant cervical cancer cells, and circ_0074269 could be delivered via exosomes. Circ_0074269 facilitated DDP resistance via elevating TUFT1 expression via sponging miR-485-5p, proving novel evidence to offer circ_0074269 as a target for cervical cancer treatment.

MiR-20a-5p functions as a potent tumor suppressor by targeting PPP6C in acute myeloid leukemia

Acute myeloid leukemia (AML) is as a highly aggressive and heterogeneous hematological malignancy. MiR-20a-5p has been reported to function as an oncogene or tumor suppressor in several tumors, but the clinical significance and regulatory mechanisms of miR-20a-5p in AML cells have not been fully understood. In this study, we found miR-20a-5p was significantly decreased in bone marrow from AML patients, compared with that in healthy controls. Moreover, decreased miR-20a-5p expression was correlated with risk status and poor survival prognosis in AML patients. Overexpression of miR-20a-5p suppressed cell proliferation, induced cell cycle G0/G1 phase arrest and apoptosis in two AML cell lines (THP-1 and U937) using CCK-8 assay and flow cytometry analysis. Moreover, miR-20a-5p overexpression attenuated tumor growth in vivo by performing tumor xenograft experiments. Luciferase reporter assay and western blot demonstrated that protein phosphatase 6 catalytic subunit (PPP6C) as a target gene of miR-20a-5p was negatively regulated by miR-20a-5p in AML cells. Furthermore, PPP6C knockdown imitated, while overexpression reversed the effects of miR-20a-5p overexpression on AML cell proliferation, cell cycle G1/S transition and apoptosis. Taken together, our findings demonstrate that miR-20a-5p/PPP6C represent a new therapeutic target for AML and a potential diagnostic marker for AML therapy.

CircSAMD11 facilitates progression of cervical cancer via regulating miR-503/SOX4 axis through Wnt/β-catenin pathway

Cervical cancer (CC) is a common gynaecological malignant tumour with a high mortality rate. Circular RNAs (circRNAs) play a critical role in tumour occurrence and development. This study aimed to investigate the function and molecular basis of hsa_circ_0009189 (circSAMD11) in CC development. RNA levels were determined by qRT-PCR, and protein expression was measured by western blot. Cell proliferation, migration, invasion and apoptosis were detected by Cell Counting Kit-8 (CCK-8), colony formation, Transwell and flow cytometry assays. The relationship between miR-503 and circSAMD11/SOX4 was validated via dual-luciferase reporter assay, RIP or RNA pull-down assay. Xenograft assay was conducted to test tumour growth in vivo. CircSAMD11 and SOX4 levels were elevated, while miR-503 level was reduced in CC tissues and cells. Knockdown of circSAMD11 suppressed CC cell proliferation, migration and invasion and accelerated apoptosis. CircSAMD11 was localised in cytoplasm and directly targeted miR-503. Also, circSAMD11 sponged miR-503 to modulate SOX4 expression. Additionally, circSAMD11 regulated CC progression via absorbing miR-503 or modulating SOX4. Besides, depletion of circSAMD11 hindered tumorigenesis in vivo. CircSAMD11 contributed to CC progression by regulating miR-503/SOX4 signalling and activating Wnt/β-catenin pathway, which provides a promising therapeutic target for cervical cancer.

Functions and Targets of miR-335 in Cancer

MicroRNAs (miRNAs) are small non-coding RNAs (18~25 nt in length) that act as master regulators of eukaryotic gene expression. They might play an oncogenic or tumor-suppressive role in multiple cancers. In recent decades, several studies have focused on the functions and mechanisms of miR-335 in cancer. The expression level of miR-335 in tissues and cells varies with cancer types, and miR-335 has been proposed as a potential biomarker for the prognosis of cancer. Besides, miR-335 may serve as an oncogene or tumor suppressor via regulating different targets or pathways in tumor initiation, development, and metastasis. Furthermore, miR-335 also influences tumor microenvironment and drug sensitivity. MiR-335 is regulated by various factors such as lncRNAs and microRNAs. In this review, we reveal the functions and targets of miR-335 in various cancers and its potential application as a possible biomarker in prognostic judgment and treatment of malignant tumors.

Investigating the Underlying Mechanisms of Circular RNAs and Their Application in Clinical Research of Cervical Cancer

Circular RNAs (circRNAs) are non-coding RNA molecules, and these are differentially expressed in various diseases, including cancer, suggesting that circRNAs can regulate certain diseases. CircRNAs can act as miRNAs sponges, RNA-binding protein (RBP) sponges, and translation regulators, and they can become an important part of the regulation of gene expression. Furthermore, because of their biomedical features in body fluids, such as high abundance, conservation, and stability, circRNAs are seen as potential biomarkers for various cancers. Cervical cancer (CC) is one of the main causes of cancer-related death in women, and there have been a large number of studies that analyze circRNAs as a new object to be evaluated in CC. Therefore, this review, by understanding the role of circRNAs in CC, may create innovative strategies in the future clinical diagnosis, treatment, and prognosis of CC and promote the development of personalized and highly accurate cancer therapy.