Circular RNA circPIP5K1A contributes to cancer stemness of osteosarcoma by miR-515-5p/YAP axis.

BACKGROUND: Osteosarcoma is a common type of bone tumors and frequently occurs in children and adolescents. Cancer stem cells (CSCs) are a unique sub-type of self-renewal cancer cells and the stemness of cancer cells are involved in the spread, recurrence, metastasis, and even therapeutic resistance. However, the regulation mechanisms of CSCs in osteosarcoma are poorly understood. Circular RNA (circRNA) is a unique sort of non-coding RNAs and widely participate in the modulation of cancer progression. METHODS: In this study, we identified the critical function of circular RNA circPIP5K1A in stemness of osteosarcoma cells. RESULTS: CircPIP5K1A expression was significantly enhanced in clinical osteosarcoma tissues compared with the adjacent normal tissues. The depletion of circPIP5K1A by siRNA repressed osteosarcoma cell viabilities and induced osteosarcoma cell apoptosis. The suppression of circPIP5K1A attenuated the capabilities of invasion and migration of osteosarcoma cells. The circPIP5K1A knockdown increased E-Cadherin expression and decreased Vimentin expression in osteosarcoma cells. The sphere formation abilities of osteosarcoma cells were repressed by the depletion of circPIP5K1A. The CD133+CD44+ cell population of osteosarcoma cells was reduced by circPIP5K1A knockdown. The expression of ALDH1 and Nanog was decreased by the inhibition of circPIP5K1A in osteosarcoma cells. Mechanically, circPIP5K1A enhanced YAP expression by targeting miR-515-5p. MiR-515-5p inhibited stemness of osteosarcoma cells. The CSCs properties of osteosarcoma cells were repressed by circPIP5K1A knockdown or miR-515-5p mimic, while miR-515-5p inhibitor or YAP overexpression reversed circPIP5K1A knockdown-induced repression. Tumor xenograft analysis in nude mice demonstrated that the depletion of circPIP5K1A represses osteosarcoma cell growth in vivo. CONCLUSION: In conclusion, we identified that circular RNA circPIP5K1A contributed to cancer stemness of osteosarcoma by miR-515-5p/YAP axis. Targeting circPIP5K1A may be considered as a potential therapeutic strategy for osteosarcoma treatment.

CircRNA PIP5K1A promotes the progression of glioma through upregulation of the TCF12/PI3K/AKT pathway by sponging miR-515-5p.

BACKGROUND: Increasing studies have revealed that circular RNAs (CircRNAs) make great contributions to regulating tumor progression. Therefore, we intended to explore the expression characteristics, function, and related mechanisms of a novel type of circRNA, PIP5K1A, in glioma. METHODS: Firstly, reverse transcription-polymerase chain reaction (RT-PCR) was carried out to examine CircPIP5K1A expression in glioma tissues and adjacent normal tissues, and the correlation between CircPIP5K1A level and the clinical-pathological indicators of glioma was analyzed. Then, the CircPIP5K1A expression in various glioma cell lines was detected, and CircPIP5K1A overexpression and knockdown cell models were constructed. Subsequently, cell proliferation and viability were detected by the CCK8 method and BrdU staining. Cell apoptosis was detected by flow cytometry, and cell invasion was examined by Transwell assay. The expression of TCF12, PI3K/AKT pathway apoptotic related proteins (Caspase3, Bax, and Bcl2) and epithelial-mesenchymal transition (EMT) markers (E-cadherin, Vimentin, and N-cadherin) was determined by western blot or RT-PCR. RESULTS: The results manifested that CircPIP5K1A was upregulated in glioma tissues (compared with that in normal adjacent tissues), and overexpressed CircPIP5K1A was related to glioma volume and histopathological grade. Functionally, overexpressing CircPIP5K1A notably elevated glioma cell proliferation, invasion, and EMT and inhibited apoptosis both in vivo and in vitro. Besides, CircPIP5K1A upregulated TCF12 and PI3K/AKT activation. Bioinformatics analysis testified that miR-515-5p was a common target of CircPIP5K1A and TCF12, while the dual-luciferase reporter assay and RNA immunoprecipitation (RIP) experiment further confirmed that CircPIP5K1A targeted miR-515-5p, which bound the 3'-untranslated region (UTR) of TCF12. CONCLUSIONS: Overall, the study illustrated that CircPIP5K1A is a potential prognostic marker in glioma and regulates glioma evolvement by modulating the miR-515-5p-mediated TCF12/PI3K/AKT axis.

CircPIP5K1A facilitates gastric cancer progression via miR-376c-3p/ZNF146 axis.

BACKGROUND: Recently, many emerging circular RNAs (circRNAs) have been studied in human malignancies, including gastric cancer (GC). Researches concerning cancers have revealed that aberrant expression of circRNAs play a big part in tumorigenesis and development of diverse malignant tumors. Although hsa_circ_0014130 (circPIP5K1A) has been confirmed to be closely related to non-small cell lung cancer (NSCLC) progression, the knowledge of its function on GC progression remains unclear. Therefore, it is of great interest to uncover the underlying role of circPIP5K1A in GC. METHODS: The expression and characteristic of circPIP5K1A were separately analyzed by RT-qPCR, nucleic acid electrophoresis, RNase R and Actinomycin D treatment. CCK-8, colony formation, EdU, transwell, TUNEL, flow cytometry, luciferase reporter, RIP and RNA pull-down assays were employed to testify the regulatory role of circPIP5K1A in GC. RESULTS: In current study, circPIP5K1A, featured with closed-loop structure, was proved to be highly expressed in tissues and cells of GC. Loss-of-function assays depicted that silencing circPIP5K1A suppressed GC development. Follow-up mechanism tests unveiled that circPIP5K1A bound with miR-376c-3p and inhibition of miR-376c-3p reversed circPIP5K1A downregulation-mediated effect on GC progression. Additionally, ZNF146 was verified to be the downstream molecule of circPIP5K1A/miR-376c-3p axis in modulating GC progression. CONCLUSIONS: circPIP5K1A stimulates GC progression by sponging miR-376c-3p to upregulate ZNF146 expression.

circPIP5K1A serves as a competitive endogenous RNA contributing to ovarian cancer progression via regulation of miR-661/IGFBP5 signaling.

Increasing evidence demonstrates the crucial regulatory functions of circular RNAs in different cancer types. The major aim of the current study was to establish functions of circPIP5K1A during ovarian cancer. Our results showed an increased expression of circPIP5K1A in both ovarian cancers and cell lines, which was associated with poor prognosis. In functional analyses, downregulation of circPIP5K1A suppressed ovarian cancer cell migration, proliferation, and invasion in vitro. The miR-661 was indicated as a target of circPIP5K1A and insulin-like growth factor-binding protein 5 (IGFBP5) as a target of miR-661. circPIP5K1A silencing triggered downregulation of IGFBP5 through inducing an increase in miR-66 levels, as determined by the luciferase reporter assay. Data from cell counting kit-8, colony formation, wound healing, and Transwell assays showed that overexpression of IGFBP5 effectively reversed the circPIP5K1A depletion effects. The results collectively indicated that circPIP5K1A contributed to ovarian cancer progression via targeting the miR-661/IGFBP5 axis, supporting its utility as a candidate target for therapy of the disease.

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.

Circular RNA PIP5K1A (circPIP5K1A) accelerates endometriosis progression by regulating the miR-153-3p/Thymosin Beta-4 X-Linked (TMSB4X) pathway.

As a common gynecologic disease, endometriosis (EM) poses a threat to the reproductive health of about 10% women globally. Recent studies have revealed that circular RNAs (circRNAs) are deeply implicated in EM pathogenesis. However, the functions of circPIP5K1A in EM have not been studied yet. Our study intended to uncover the molecular mechanism of circPIP5K1A in EM. In this work, gene and protein expressions were determined by RT-qPCR or Western blotting. CCK-8, wound healing, transwell, and flow cytometry assays were conducted to analyze cell viability, migration, invasion, cell cycle, and apoptosis. Additionally, bioinformatics analysis, dual-luciferase reporter assay, as well as RIP assay were performed to investigate the combination between miR-153-3p and circPIP5K1A or TMSB4X. Herein, we found remarkable high circPIP5K1A expression in EM tissues and cells. Silencing of circPIP5K1A suppressed proliferation, restrained cell cycle, increased cell apoptosis, and decreased migration and invasion in EM cells. In addition, miR-153-3p inhibition could abrogate the impacts of circPIP5K1A knockdown on EM progression in vitro. Also, we found that circPIP5K1A regulated TMSB4X level via interaction with miR-153-3p in EM cells. Besides, circPIP5K1A promoted EM progression via TMSB4X. Moreover, TMSB4X could activate the TGF-ß signaling in hEM15A cells. To sum up, our study elucidated that circPIP5K1A accelerated EM progression in vitro by activating the TGF-ß signaling pathway via the miR-153-3p/TMSB4X axis, providing a potential clinical target for EM treatment.

CircPIP5K1A activates KRT80 and PI3K/AKT pathway to promote gastric cancer development through sponging miR-671-5p.

BACKGROUND: Gastric cancer (GC) has been regarded as a kind of the most common cancers in gastrointestinal malignant tumors. Circular RNA (circRNA) is a newly discovered category of non-coding RNAs and plays a significant role in the initiation or development of human cancers. Nevertheless, the role of circPIP5K1A in GC remains unclear. METHODS: The relative expression level and the circular structure of circPIP5K1A were confirmedby RT-qPCR. The biological function of circPIP5K1A in GC was evaluated by colony formation, transwell and western blot assays. The binding capacity between miR-671-5p and circPIP5K1A (or KRT80) was assessed by luciferase reporter and Ago2-RIP assays. Protein levels of PI3K/AKT pathway were measured by western blot assay. RESULTS: CircPIP5K1A was up-regulated in GC tissues and cells with a circular structure. Functionally, circPIP5K1A silence limited cell proliferation, invasion, migration and EMT process. Mechanistically, circPIP5K1A directly interacted with miR-671-5p to modulate KRT80 expression. Either miR-671-5p inhibitor or KRT80 overexpression could offset the inhibitory effect of circPIP5K1A depletion on GC development. Besides, circPIP5K1A played its oncogenic role in GC through regulating PI3K/AKT pathway. At last, circPIP5K1A promoted GC tumor growth in vivo. CONCLUSIONS: CircPIP5K1A/miR-671-5p/KRT80 axis contributes to GC progression through PI3K/AKT pathway, implying this axis may be a potential therapeutic target for the treatment of GC patients.