CircRNA-100284 activates aurora kinase B by inducing methylation of HSP70 via microRNA-217 to promote proliferation of bladder cancer cells

Molecular mechanism of microRNAs, long noncoding RNAs, and circular RNAs regulating lymphatic metastasis of bladder cancer

Bladder cancer (BC), a malignancy originating in the epithelial tissue in the inner wall of the bladder, is a common urological cancer type. BC spreads through 3 main pathways: direct infiltration, lymphatic metastasis, and hematogenous metastasis. Lymphatic metastasis is considered a poor prognostic factor for BC and is often associated with lower survival rates. The treatment of BC after lymphatic metastasis is complex and challenging. A deeper understanding of the molecular mechanisms underlying lymphatic metastasis of BC may yield potential targets for its treatment. Here, we summarize the current knowledge on epigenetic factors-including miRNAs, lncRNAs, and circRNAs-associated with lymphatic metastasis in BC. These factors are strongly associated with lymphangiogenesis, cancer cell proliferation and migration, and epithelial-mesenchymal transition processes, providing new insights to develop newer BC treatment strategies.

The Role of microRNAs in Arsenic-Induced Human Diseases: A Review

MicroRNAs (miRNAs) are noncoding RNAs with 20-22 nucleotides, which are encoded by endogenous genes and are capable of targeting the majority of human mRNAs. Arsenic is regarded as a human carcinogen, which can lead to many adverse health effects including diabetes, skin lesions, kidney disease, neurological impairment, male reproductive injury, and cardiovascular disease (CVD) such as cardiac arrhythmias, ischemic heart failure, and endothelial dysfunction. miRNAs can act as tumor suppressors and oncogenes via directly targeting oncogenes or tumor suppressors. Recently, miRNA dysregulation was considered to be an important mechanism of arsenic-induced human diseases and a potential biomarker to predict the diseases caused by arsenic exposure. Endogenic miRNAs such as miR-21, the miR-200 family, miR-155, and the let-7 family are involved in arsenic-induced human disease by inducing translational repression or RNA degradation and influencing multiple pathways, including mTOR/Arg 1, HIF-1α/VEGF, AKT, c-Myc, MAPK, Wnt, and PI3K pathways. Additionally, exogenous miRNAs derived from plants, such as miR-34a, miR-159, miR-2911, miR-159a, miR-156c, miR-168, etc., among others, can be transported from blood to specific tissue/organ systems in vivo. These exogenous miRNAs might be critical players in the treatment of human diseases by regulating host gene expression. This review summarizes the regulatory mechanisms of miRNAs in arsenic-induced human diseases, including cancers, CVD, and other human diseases. These special miRNAs could serve as potential biomarkers in the management and treatment of human diseases linked to arsenic exposure. Finally, the protective action of exogenous miRNAs, including antitumor, anti-inflammatory, anti-CVD, antioxidant stress, and antivirus are described.

Bladder cancer tissue-derived exosomes suppress ferroptosis of T24 bladder cancer cells by transporting miR-217

It has been reported that miR-217 can inhibit the oncogenic activity and progression of bladder cancer (BCa) cells, but it has not been explored whether miR-217 is involved in the regulation of ferroptosis. In the present study, RNA transfection, real-time PCR, flow cytometry, Western blotting assays, immunofluorescence and ELISA were performed to explore the effects and mechanisms of miR-217 in BCa tissue-derived exosomes. We found that extracellular fluid from bladder cancer tissue promoted the growth and miR-217 expression of T24 cells and inhibited ferroptosis. MiR-217 was confirmed to inhibit ferroptosis in bladder cancer cells by RNA interference and functional assays. By cell membrane fluorescence probe (CM-Dil) labeling, inhibiting exosome secretion by GW4689 and exosome extraction, we determined that BCa tissue-derived exosomes transport miR-217 into T24 cells. Culture of T24 cells with extracellular fluid after RNA interference showed that exosomes carrying miR-217 derived from BCa tissues inhibited ferroptosis of T24 cells. We conclude that bladder cancer tissue-derived exosomes inhibit ferroptosis of T24 bladder cancer cells by transporting miR-217. The results of our study provide a new insight into the progression of bladder cancer.

Interactions of circRNAs with methylation: An important aspect of circRNA biogenesis and function (Review)

Circular RNA (circRNA) molecules are noncoding RNAs with unique circular covalently closed structures that contribute to gene expression regulation, protein translation and act as microRNA sponges. circRNAs also have important roles in human disease, particularly tumorigenesis and antitumor processes. Methylation is an epigenetic modification that regulates the expression and roles of DNA and coding RNA and their interactions, as well as of noncoding RNA molecules. Previous studies have focused on the effects of methylation modification on circRNA expression, transport, stability, translation and degradation of circRNAs, as well as how circRNA methylation occurs and the influence of circRNAs on methylation modification processes. circRNA and methylation can also regulate disease pathogenesis via these interactions. In the present study, we define the relationship between circRNAs and methylation, as well as the functions and mechanisms of their interactions during disease progression.

Circular RNA circGLIS3 promotes bladder cancer proliferation via the miR-1273f/SKP1/Cyclin D1 axis

Extensive research confirmed that circRNA can play a regulatory role in various stages of tumors by interacting with various molecules. Identifying the differentially expressed circRNA in bladder cancer and exploring its regulatory mechanism on bladder cancer progression are urgent. In this study, we screened out a circRNA-circGLIS3 with a significant upregulation trend in both bladder cancer tissues and cells. Bioinformatics prediction results showed that circGLIS3 may be involved in multiple tumor-related pathways. Function gain and loss experiments verified circGLIS3 can affect the proliferation, migration, and invasion of bladder cancer cells in vitro. Moreover, silencing circGLIS3 inhibited bladder cancer cell growth in vivo. Subsequent research results indicated circGLIS3 regulated the expression of cyclin D1, a cell cycle–related protein, and cell cycle progression. Mechanically, circGLIS3 upregulates the expression of SKP1 by adsorbing miR-1273f and then promotes cyclin D1 expression, ultimately promoting the proliferation of bladder cancer cells. In summary, our study indicates that circGLIS3 plays an oncogene role in the development of bladder cancer and has potential to be a candidate for bladder cancer.