Research over the past decade suggested critical roles for circular RNAs in the natural growth and disease progression. However, it remains poorly defined whether the circular RNAs participate in Hirschsprung disease (HSCR). Here, we reported that the cir-ZNF609 was down-regulated in HSCR compared with normal bowel tissues. Furthermore, suppression of cir-ZNF609 inhibited the proliferation and migration of cells. We screened out several putative cir-ZNF609 ceRNAs of which the AKT3 transcript was selected. Finally, RNA immunoprecipitation and luciferase reporter assays demonstrated that cir-ZNF609 may act as a sponge for miR-150-5p to modulate the expression of AKT3. In conclusion, these findings illustrated that cir-ZNF609 took part in the onset of HSCR through the crosstalk with AKT3 by competing for shared miR-150-5p.
KLF5 (Krüppel-like factor 5) plays critical roles in normal and cancer cell proliferation through modulating cell cycle progression. In this study, we demonstrated that curcumin targeted KLF5 by promoting its proteasome degradation, but not by inhibiting its transcription in bladder cancer cells. We also demonstrated that lentivirus-based knockdown of KLF5 inhibited cancer cell growth, while over-expression of a Flag-tagged KLF5 could partially reverse the effects of curcumin on cell growth and cyclin D1 expression. Furthermore, we found that curcumin could down-regulate the expression of Hippo pathway effectors, YAP and TAZ, which have been reported to protect KLF5 protein from degradation. Indeed, knockdown of YAP by small interfering RNA caused the attenuation of KLF5 protein, but not KLF5 mRNA, which was reversed by co-incubation with proteasome inhibitor. A xenograft assay in nude mice finally proved the potent inhibitory effects of curcumin on tumor growth and the pro-proliferative YAP/TAZ/KLF5/cyclin D1 axis. Thus, our data indicates that curcumin promotes KLF5 proteasome-dependent degradation through targeting YAP/TAZ in bladder cancer cells and also suggests the therapeutic potential of curcumin in the treatment of bladder cancer.
H19 is a long noncoding RNA differentially expressed in many tumors and participates in tumorigenesis. This study aimed to investigate the expression and function of H19 in pancreatic ductal adenocarcinoma (PDAC). Pure malignant cells were isolated from frozen sections of 25 PDAC cases by laser captured microdessection, and H19 expression level was detected by qRT-PCR. Knockdown and overexpression were employed to manipulate H19 levels in pancreatic cancer cells, then cell viability, proliferation, apoptosis and cell cycle, and the growth of xenografts were evaluated. E2F-1 levels in PDAC tissues were detected by Western blot and immunohistochemical analysis. We found that H19 was overexpressed in PDAC tissues and correlated to histological grade of PDAC. Knockdown of H19 in T3M4 and PANC-1 cells with high H19 endogenous level suppressed cell viability, proliferation and tumor growth, while H19 overexpression in COLO357 and CAPAN-1 with low H19 endogenous level enhanced cell viability, proliferation and tumor growth. Knockdown of H19 led to G0/G1 arrest, accompanied by decreased levels of E2F-1 and its downstream targets. E2F-1 was overexpressed in PDAC tissues with possible correlation with H19 expression level. In conclusion, H19 is overexpressed and plays oncogenic role in PDAC through promoting cancer cell proliferation via the upregulation of E2F-1.
Abundant evidence has demonstrated critical roles of KLF5 in regulating cell proliferation in various cancers, however, its additional roles in other aspects of cancer development remain to be further clarified. In this study, we found that KLF5 was essential for cancer cell-endothelial cell interaction in vitro and tumor angiogenesis in nude mice based on lentivirus-mediated KLF5 knockdown bladder cancer cell models. Moreover, KLF5 insufficiency abolished the ability of bladder cancer cells to induce neovascularization in rabbit cornea. Mechanistically, the pro-angiogenic factor VEGFA was identified as a direct downstream target of KLF5, which bound to GC-boxes and CACCC elements of VEGFA promoter and regulated its transcriptional activity. In addition, there was a positive correlation between KLF5 and VEGFA expression in human bladder cancer tissues by immunohistochemistry assay and statistical analysis from TCGA and GEO data. Furthermore, we found that two pivotal pathways in bladder cancer, RTKs/RAS/MAPK and PI3K/Akt, might convey their oncogenic signaling through KLF5-VEGFA axis. Taken together, our results indicate that KLF5 promotes angiogenesis of bladder cancer through directly regulating VEGFA transcription and suggest that KLF5 could be a novel therapeutic target for angiogenesis inhibition in bladder cancer.
Pancreatic cancer (PCa) is one of the most lethal malignancies, with a 5 year survival rate of less than 8%. Current treatment regiments have a low response rate in unselected patients. However, the subgroup of PCa patients with BRCA mutations may benefit from poly-ADP-ribose polymerase inhibitors (PARPi) due to their biological properties in DNA repair. Doselimiting toxicity in normal tissues is frequently observed when PARPi are combined with other chemotherapies, and the co-delivery of two drugs to tumor sites at an adequate concentration is challenging. To address this issue, we have engineered an epidermal growth factor receptor (EGFR) targeting (with GE11 peptide) self-assembly amphiphilic peptide nanoparticle (GENP) to co-deliver gemcitabine and the PARPi olaparib to treat BRCA mutant PCa. The GENP was relatively stable, exhibited high encapsulation efficiency, and could coordinately release the two drugs in tumor milieu. Gemcitabine and olaparib showed strong synergistic actions in optimized conditions in vitro. The nanoparticle prolonged the half-life of both drugs and resulted in their tumor accumulation at the optimal therapeutic ratio in vivo. The drug-loaded nanoparticles were able to significantly suppress tumor growth in a murine PCa model with minimal side effects. Drug codelivery of DNA damaging agents and PARP inhibitors via the GENP represents a promising approach for treatment of pancreatic cancers with molecular defects in the DNA repair pathway.
The long noncoding RNA (lncRNA) H19 has been proven to be overexpressed in human pancreatic ductal adenocarcinoma (PDAC). H19-induced PDAC cell proliferation is cell cycle-dependent by modulating E2F-1. However, the mechanism of how H19 regulates E2F-1 remains unclear. In this study, we investigated the expression of miR-675 in PDAC tumours and cells, the biological function of miR-675 in PDAC cell proliferation and the possible relationship among H19, miR-675 and E2F-1. As a transcript of the first exon of H19, the level of miR-675 was negatively correlated with H19 expression in microdissected PDAC tissues (r=-0.0646, P=0.001). The serum miR-675 expression was significantly down-regulated in patients with PDAC compared to those in healthy individuals. Moreover, an evaluation of five PDAC cases showed that there was a remarkable increase of serum miR-675 levels after resection of the primary tumours. Ectopic overexpression of miR-675 in AsPC-1 and PANC-1 cells decreased cell viability, the colony-forming ability and the percentage of cells in S phase; contrarily, miR-675 knockdown resulted in enhanced cell proliferation. Furthermore, the suppressed cell proliferation caused by H19 knockdown could be rescued by inhibiting miR-675 expression. Additionally, intratumoural injection of either miR-675 agomir or antagomir could significantly affect tumour growth in vivo. Both the bioinformatic prediction and luciferase activity assay confirmed that E2F-1 was a direct target of miR-675. And the decrease of E2F-1 protein expression caused by siH19 could be partially reversed by miR-675 knockdown. We concluded that there might be a H19/miR-675/E2F-1 regulatory loop in cell cycle modulation. Serum miR-675 might serve as a potential biomarker for not only early diagnosis but also outcome prediction in PDAC.
Long non-coding RNA (lncRNA) MEG3 has been demonstrated to be a tumour suppressor in many malignancies. However, the functional role of MEG3 in pancreatic cancer (PC) is unclear. In this study, the expression pattern of MEG3 was evaluated in 25 samples of microdissected PC tissues and 8 PC cell lines and was compared to the expression in adjacent non‑cancerous tissues and a human pancreatic normal epithelial cell line. Loss of MEG3 expression was observed in both the cancerous tissues and cancer cell lines. Although the absence of expression of MEG3 was not statistically correlated to either histological grade or TNM stage in the 25 cases, the prognosis was significantly worse. MEG3 knockdown enhanced cell proliferation, promoted cell migration and invasion, induced epithelial‑mesenchymal transition (EMT), increased the sphere‑forming ability and cancer stem cell (CSC) properties, and decreased the chemosensitivity to gemcitabine in vitro. In contrast, forced expression of MEG3 resulted in a reverse effect. In conclusion, MEG3 functions as a tumour suppressor in human PC. The underlying cause of the poor prognosis induced by low levels of MEG3 expression in PC patients might involve EMT induction, enhanced CSC phenotypes and reduced chemoresistance, all of which might be associated with Snail activation.
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