[Retracted] Role of the AKT pathway in microRNA expression of human U251 glioblastoma cells.

Following the publication of the above article, a concerned reader drew to the Editor's attention that, regarding the western blots featured in Fig. 3B on p. 670, the bands featured in the U251 and U251­MC lanes for the miR­21 and U6 experiments appeared to be duplicates of each other. Moreover, certain of these data were strikingly similar to data that appeared in another article published at around the same time featuring some of the same authors (again, with apparent duplications of bands within the same gel slices, as they were presented). After having conducted an internal investigation of this matter, the Editor of International Journal of Oncology has judged that the apparently anomalous grouping of the data could not have been attributed to pure coincidence. Therefore, the Editor has decided that this article should be retracted from the publication on the grounds of an overall lack of confidence in the data. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor sincerely apologizes to the readership for any incovenience caused, and we thank the reader for bringing this matter to our attention. [International Journal of Oncology 36: 665­672, 2010; DOI: 10.3892/ijo_00000542].

MUC1 promotes glioblastoma progression and TMZ resistance by stabilizing EGFRvIII.

Epidermal growth factor receptor variant III (EGFRvIII) is a mutant isoform of EGFR with a deletion of exons 2-7 making it insensitive to EGF stimulation and downstream signal constitutive activation. However, the mechanism underlying the stability of EGFRvIII remains unclear. Based on CRISPR-Cas9 library screening, we found that mucin1 (MUC1) is essential for EGFRvIII glioma cell survival and temozolomide (TMZ) resistance. We revealed that MUC1-C was upregulated in EGFRvIII-positive cells, where it enhanced the stability of EGFRvIII. Knockdown of MUC1-C increased the colocalization of EGFRvIII and lysosomes. Upregulation of MUC1 occurred in an NF-κB dependent manner, and inhibition of the NF-κB pathway could interrupt the EGFRvIII-MUC1 feedback loop by inhibiting MUC1-C. In a previous report, we identified AC1Q3QWB (AQB), a small molecule that could inhibit the phosphorylation of NF-κB. By screening the structural analogs of AQB, we obtained EPIC-1027, which could inhibit the NF-κB pathway more effectively. EPIC-1027 disrupted the EGFRvIII-MUC1-C positive feedback loop in vitro and in vivo, inhibited glioma progression, and promoted sensitization to TMZ. In conclusion, we revealed the pivotal role of MUC1-C in stabilizing EGFRvIII in glioblastoma (GBM) and identified a small molecule, EPIC-1027, with great potential in GBM treatment.

Identification of long non-coding RNA HERC2P2 as a tumor suppressor in glioma.

Long non-coding RNAs (lncRNAs) have been reported to play important roles in glioma; however, most of them promote glioma progression. We constructed a competing endogenous (ceRNA) network based on the Chinese Glioma Genome Atlas dataset, and lncRNA hect domain and RLD 2 pseudogene 2 (HERC2P2) is the core of this network. Highly connected genes in the ceRNA network classified the glioma patients into three clusters with significantly different survival rates. The expression of HERC2P2 is positively correlated with survival and negatively correlated with clinical grade. Cell colony formation, Transwell and cell scratch tests were performed to evaluate the role of HERC2P2 in glioblastoma growth. Furthermore, we overexpressed HERC2P2 in U87 cells and established a mouse intracranial glioma model to examine the function of HERC2P2 in vivo. In conclusion, we identified a lncRNA with tumor suppressor functions in glioma that could be a potential biomarker for glioma patients.

Targeted design and identification of AC1NOD4Q to block activity of HOTAIR by abrogating the scaffold interaction with EZH2.

BACKGROUND: Nearly 25% of long intergenic non-coding RNAs (lincRNAs) recruit chromatin-modifying proteins (e.g., EZH2) to silence target genes. HOX antisense intergenic RNA (HOTAIR) is deregulated in diverse cancers and could be an independent and powerful predictor of eventual metastasis and death. Yet, it is challenging to develop small molecule drugs to block activity of HOTAIR with high specificity in a short time. RESULTS: Our previous study proved that the 5' domain, but not its 3' domain, was the function domain of HOTAIR responsible for tumorigenesis and metastasis in glioblastoma and breast cancer, by recruiting and binding EZH2. Here, we targeted to establish a structure-based methodology to identify lead compounds of HOTAIR, by abrogating scaffold interactions with EZH2. And a small compound AC1NOD4Q (ADQ) was identified by high-throughput molecular docking-based virtual screening of the PubChem library. Our analysis revealed that ADQ was sufficiently and specifically interfering HOTAIR/EZH2 interaction, thereby impairing the H3K27-mediated tri-methylation of NLK, the target of HOTAIR gene, and consequently inhibiting tumor metastasis through Wnt/ß-catenin pathway in vitro and in orthotopic breast cancer models. The results of RIP and EMSA further revealed that 36G46A of 5' domain was the essential binding site for ADQ exerted its inhibitory effect, further narrowed the structure and function of HOTAIR from the 5' functional domain to the micro-domain. CONCLUSIONS: Our findings suggest of a potential new strategy to discover the lead compound for targeted lincRNA therapy and potentially pave the way for exploiting ADQ as a scaffold for more effective small molecule drugs.

m6A RNA methylation regulators contribute to malignant progression and have clinical prognostic impact in gliomas.

N6-methyladenosine (m6A) RNA methylation, associated with cancer initiation and progression, is dynamically regulated by the m6A RNA methylation regulators ("writers", "erasers" and "readers"). Here, we demonstrate that most of the thirteen main m6A RNA methylation regulators are differentially expressed among gliomas stratified by different clinicopathological features in 904 gliomas. We identified two subgroups of gliomas (RM1/2) by applying consensus clustering to m6A RNA methylation regulators. Compared with the RM1 subgroup, the RM2 subgroup correlates with a poorer prognosis, higher WHO grade, and lower frequency of IDH mutation. Moreover, the hallmarks of epithelial-mesenchymal transition and TNFα signaling via NF-κB are also significantly enriched in the RM2 subgroup. This finding indicates that m6A RNA methylation regulators are closely associated with glioma malignancy. Based on this finding, we derived a risk signature, using seven m6A RNA methylation regulators, that is not only an independent prognostic marker but can also predict the clinicopathological features of gliomas. Moreover, m6A regulators are associated with the mesenchymal subtype and TMZ sensitivity in GBM. In conclusion, m6A RNA methylation regulators are crucial participants in the malignant progression of gliomas and are potentially useful for prognostic stratification and treatment strategy development.

Paracrine and epigenetic control of CAF-induced metastasis: the role of HOTAIR stimulated by TGF-ß1 secretion.

BACKGROUND: The communication between carcinoma associated fibroblasts (CAFs) and cancer cells facilitate tumor metastasis. In this study, we further underlying the epigenetic mechanisms of CAFs feed the cancer cells and the molecular mediators involved in these processes. METHODS: MCF-7 and MDA-MB-231 cells were treated with CAFs culture conditioned medium, respectively. Cytokine antibody array, enzyme-linked immunosorbent assay, western blotting and immunofluorescence were used to identify the key chemokines. Chromatin immunoprecipitation and luciferase reporter assay were performed to explore the transactivation of target LncRNA by CAFs. A series of in vitro assays was performed with RNAi-mediated knockdown to elucidate the function of LncRNA. An orthotopic mouse model of MDA-MB-231 was conducted to confirm the mechanism in vivo. RESULTS: Here we reported that TGF-ß1 was top one highest level of cytokine secreted by CAFs as revealed by cytokine antibody array. Paracrine TGF-ß1 was essential for CAFs induced EMT and metastasis in breast cancer cells, which is a crucial mediator of the interaction between stromal and cancer cells. CAF-CM significantly enhanced the HOTAIR expression to promote EMT, whereas treatment with small-molecule inhibitors of TGF-ß1 attenuated the activation of HOTAIR. Most importantly, SMAD2/3/4 directly bound the promoter site of HOTAIR, located between nucleotides -386 and -398, -440 and -452, suggesting that HOTAIR was a directly transcriptional target of SMAD2/3/4. Additionally, CAFs mediated EMT by targeting CDK5 signaling through H3K27 tri-methylation. Depletion of HOTAIR inhibited CAFs-induced tumor growth and lung metastasis in MDA-MB-231 orthotopic animal model. CONCLUSIONS: Our findings demonstrated that CAFs promoted the metastatic activity of breast cancer cells by activating the transcription of HOTAIR via TGF-ß1 secretion, supporting the pursuit of the TGF-ß1/HOTAIR axis as a target in breast cancer treatment.

EGFR/EGFRvIII remodels the cytoskeleton via epigenetic silencing of AJAP1 in glioma cells.

EGFR amplification and mutations are the most common oncogenic events in GBM. EGFR overexpression correlates with GBM invasion, but the underlying mechanisms are poorly understood. In a previous study, we showed that AJAP1 is involved in regulating F-actin to inhibit the invasive ability of GBM. In addition, in a GBM cell line, the AJAP1 promoter was highly bound by H3K27me3 and, through bioinformatics analysis, we found that AJAP1 expression was negatively correlated with EGFR. In this study, we found that the pathway downstream of EGFR had a higher activation level in GBM cell lines, which led to excessive tumor suppressor silencing. Therefore, we deduced that in glioma cells, the pathway downstream of EGFR remodels the cytoskeleton via AJAP1 epigenetic silencing to enhance invasion. Furthermore, MK2206 reversed AJAP1 downregulation by inhibiting the EGFR pathway. In vivo, MK2206 also inhibited the proliferation and local invasion of 87-EGFRvIII. These data suggest that activation of the EGFR signal transduction pathway genetically silences anti-oncogenes to enhance GBM malignancy. MK2206 might be a promising therapeutic for EGFR/EGFRvIII-positive GBMs.

SNORD47, a box C/D snoRNA, suppresses tumorigenesis in glioblastoma.

SNORD47 is a member of the C/D box small nucleolar RNAs, which have been implicated in cancer development. We intended to investigate the therapeutic potential of SNORD47 in glioma. We found that the expression of SNORD47 was downregulated in glioma tissues samples and inversely associated with advanced tumor stage (WHO grade IV). Kaplan-Meier survival analysis revealed that glioma patients with high SNORD47 expression had longer overall survival than those with low SNORD47 expression. SNORD47 suppressed the proliferation of glioma cells and induced G2 phase arrest. In addition, upregulation of SNORD47 suppressed invasion and epithelial-mesenchymal transition in glioma cells, and combination treatment with lenti-SNORD47 could augment the anti-tumor effect of temozolomide. These results showed that SNORD47 acted as a tumor suppressor in glioma, and provided the potential anti-tumor function in glioma treatment.

Signal Peptide Peptidase, Encoded by HM13, Contributes to Tumor Progression by Affecting EGFRvIII Secretion Profiles in Glioblastoma.

BACKGROUND AND AIMS: EGFRvIII is the most prevalent glioblastoma mutation, occurring in more than 25% of glioblastomas. EGFRvIII cells release microvesicles that contain proteins, miRNAs, and mRNAs that enhance the growth and survival of surrounding tumor cells. However, little is known about the maturation process and regulatory mechanisms of secreted vesicles in EGFRvIII cells. METHODS: Signal peptide peptidase (SPP) provides a fascinating mechanism for protein cleavage and subsequent dislocation in the endoplasmic reticulum transmembrane domain. RESULTS: In this study, we reported that SPP facilitates the secretion of cytokines in vitro and promotes tumor progression in mice. Human cytokine antibody arrays revealed that EGFRvIII secreted higher levels of cytokines, but these levels were significantly reduced following SPP knockdown, suggesting that cytokines in EGFRvIII secretion profiles play important roles in GBM development. Identical results were confirmed in intracellular maturation tracking of TGF-ß1 in mouse serum. Clinically, analyses of GBM patient data from the database revealed that HM13 expression was closely related to patient prognosis and survival, suggesting an influence by the secreted vesicles of EGFRvIII tumor cells. CONCLUSIONS: Collectively, our study identifies that SPP affects EGFRvIII secretion profiles and thus promotes tumor progression, providing further understanding of the formation of secreted vesicles and driving role of EGFRvIII in GBM.

The CRISPR/Cas9 system targeting EGFR exon 17 abrogates NF-κB activation via epigenetic modulation of UBXN1 in EGFRwt/vIII glioma cells.

Worldwide, glioblastoma (GBM) is the most lethal and frequent intracranial tumor. Despite decades of study, the overall survival of GBM patients remains unchanged. epidermal growth factor receptor (EGFR) amplification and gene mutation are thought to be negatively correlated with prognosis. In this study, we used proteomics to determine that UBXN1 is a negative downstream regulator of the EGFR mutation vIII (EGFRvIII). Via bioinformatics analysis, we found that UBXN1 is a factor that can improve glioma patients' overall survival time. We also determined that the down-regulation of UBXN1 is mediated by the upregulation of H3K27me3 in the presence of EGFRvIII. Because NF-κB can be negatively regulated by UBXN1, we believe that EGFRwt/vIII activates NF-κB by suppressing UBXN1 expression. Importantly, we used the latest genomic editing tool, CRISPR/Cas9, to knockout EGFRwt/vIII on exon 17 and further proved that UBXN1 is negatively regulated by EGFRwt/vIII. Furthermore, knockout of EGFR/EGFRvIII could benefit GBM in vitro and in vivo, indicating that CRISPR/Cas9 is a promising therapeutic strategy for both EGFR amplification and EGFR mutation-bearing patients.

EGFL7 is an intercellular EGFR signal messenger that plays an oncogenic role in glioma.

Epidermal Growth Factor like domain 7 (EGFL7), also known as Vascular Endothelial-statin (VE-statin), is a secreted angiogenic factor. Recent data have demonstrated the potential oncogenic role and prognostic significance of EGFL7 in several human cancers. However, the clinical signature and further mechanisms of EGFL7's function in gliomagenesis are poorly understood. In the present study, we found that increased EGFL7 expression was associated with tumor grade. High expression of EGFL7 in EGFRvIII-positive glioblastoma multiforme (GBM) was determined to be a strong and independent risk factor for reduced life expectancy. EGFRvIII cells can secrete the EGFL7 protein to improve the activity of the ß-catenin/TCF4 Transcription complex in EGFRwt cells, thus promoting their own EGFL7 expression. Our research demonstrates that oncogenic activation of EGFRwt in GBM is likely maintained by a continuous EGFL7 autocrine flow line, and may be an attractive target for therapeutic intervention.

Non-coding RNAs as regulators in epigenetics (Review).

Epigenetics is a discipline that studies heritable changes in gene expression that do not involve altering the DNA sequence. Over the past decade, researchers have shown that epigenetic regulation plays a momentous role in cell growth, differentiation, autoimmune diseases, and cancer. The main epigenetic mechanisms include the well-understood phenomenon of DNA methylation, histone modifications, and regulation by non-coding RNAs, a mode of regulation that has only been identified relatively recently and is an area of intensive ongoing investigation. It is generally known that the majority of human transcripts are not translated but a large number of them nonetheless serve vital functions. Non-coding RNAs are a cluster of RNAs that do not encode functional proteins and were originally considered to merely regulate gene expression at the post-transcriptional level. However, taken together, a wide variety of recent studies have suggested that miRNAs, piRNAs, endogenous siRNAs, and long non-coding RNAs are the most common regulatory RNAs, and, significantly, there is a growing body of evidence that regulatory non-coding RNAs play an important role in epigenetic control. Therefore, these non-coding RNAs (ncRNAs) highlight the prominent role of RNA in the regulation of gene expression. Herein, we summarize recent research developments with the purpose of coming to a better understanding of non-coding RNAs and their mechanisms of action in cells, thus gaining a preliminary understanding that non-coding RNAs feed back into an epigenetic regulatory network.

F25P preproinsulin abrogates the secretion of pro-growth factors from EGFRvIII cells and suppresses tumor growth in an EGFRvIII/wt heterogenic model.

Extensive heterogeneity is a defining hallmark of glioblastoma multiforme (GBM) at the cellular and molecular levels. EGFRvIII, the most common EGFR mutant, is expressed in 24-67% of cases and strongly indicates a poor survival prognosis. By co-expressing EGFRvIII and EGFRwt, we established an EGFRvIII/wt heterogenic model. Using this approach, we confirmed that a mixture of EGFRvIII and EGFRwt at a certain ratio could clearly enhance tumor growth in vitro and in vivo compared with EGFRwt cells, thereby indicating that EGFRvIII cells promote tumor growth. Furthermore, we demonstrated that the EGFRvIII cells could support the growth of EGFRwt cells by secreting growth factors, thus acting as the principal source for maintaining tumor survival. F25P preproinsulin effectively reduced the concentrations of EGF, VEGF, and MMP-9 in the blood of tumor-bearing mice by competitively inhibiting the endoplasmic reticulum signal peptidase and increased the overall survival in orthotopic models. Taken together, our results provided an effective therapy of F25P preproinsulin in the EGFRvIII/wt heterogenic model.

Reprogramming carcinoma associated fibroblasts by AC1MMYR2 impedes tumor metastasis and improves chemotherapy efficacy.

Carcinoma associated fibroblasts (CAFs) produce a nutrient-rich microenvironment to fuel tumor progression and metastasis. Reactive oxygen species (ROS) levels and the inflammation pathway co-operate to transform CAFs. Therefore, elucidating the mechanism mediating the activity of CAFs might identify novel therapies. Abnormal miR-21 expression was reported to be involved in the conversion of resident fibroblasts to CAFs, yet the factor that drives transformation was poorly understood. Here, we reported that high miR-21 expression was strongly associated with lymph node metastasis in breast cancer, and the activation of the miR-21/NF-кB was required for the metastatic promoting effect of CAFs. AC1MMYR2, a small molecule inhibitor of miR-21, attenuated NF-кB activity by directly targeting VHL, thereby blocking the co-precipitation of NF-кB and ß-catenin and nuclear translocation. Taxol failed to constrain the aggressive behavior of cancer cells stimulated by CAFs, whereas AC1MMYR2 plus taxol significantly suppressed tumor migration and invasion ability. Remodeling and depolarization of F-actin, decreased levels of ß-catenin and vimentin, and increased E-cadherin were also detected in the combination therapy. Furthermore, reduced levels of FAP-α and α-SMA were observed, suggesting that AC1MMYR2 was competent to reprogram CAFs via the NF-кB/miR-21/VHL axis. Strikingly, a significant reduction of tumor growth and lung metastasis was observed in the combination treated mice. Taken together, our findings identified miR-21 as a critical mediator of metastasis in breast cancer through the tumor environment. AC1MMYR2 may be translated into the clinic and developed as a more personalized and effective neoadjuvant treatment for patients to reduce metastasis and improve the chemotherapy response.

AC1MMYR2 impairs high dose paclitaxel-induced tumor metastasis by targeting miR-21/CDK5 axis.

Paclitaxel (taxol) is a widely used chemo-drug for many solid tumors, while continual taxol treatment is revealed to stimulate tumor dissemination. We previously found that a small molecule inhibitor of miR-21, termed AC1MMYR2, had the potential to impair tumorigenesis and metastasis. The aim of this study was to investigate whether combining AC1MMYR2 with taxol could be explored as a means to limit tumor metastasis. Here we showed that abnormal activation of miR-21/CDK5 axis was associated with breast cancer lymph node metastasis, which was also contribute to high dose taxol-induced invasion and epithelial mesenchymal transition (EMT) in both breast cancer cell line MDA-MB-231 and glioblastoma cell line U87VIII. AC1MMYR2 attenuated CDK5 activity by functional targeting CDK5RAP1, CDK5 activator p39 and target p-FAK(ser732). A series of in vitro assays indicated that treatment of AC1MMYR2 combined with taxol suppressed tumor migration and invasion ability in both MDA-MB-231 and U87VIII cell. More importantly, combination therapy impaired high-dose taxol induced invadopodia, and EMT markers including ß-catenin, E-cadherin and vimentin. Strikingly, a significant reduction of lung metastasis in mice was observed in the AC1MMYR2 plus taxol treatment. Taken together, our work demonstrated that AC1MMYR2 appeared to be a promising strategy in combating taxol induced cancer metastasis by targeting miR-21/CDK5 axis, which highlighted the potential for development of therapeutic modalities for better clinic taxol application.

[DZNep raises miR-200c expression to delay the invasion and migration of MGC-803 gastric carcinoma cells].

The aim of the present study was to investigate the regulatory effects of histone methylation modifications on the expression of miR-200c, as well as invasion and migration of gastric carcinoma cells. Gastric carcinoma cell line, MGC-803, were treated by 2.5 µmol/L histone methyltransferase inhibitor, DZNep. The expression of miR-200c was detected by real-time quantitative PCR (qRT-PCR). The epithelial-mesenchymal transition (EMT) indicators (ZEB1/2 and E/N-cadherin), EZH2, EED, SUZ12 and H3K27me3 expressions were detected by Western blot. Cell migration and invasion abilities were detected by Transwell and scratch tests. The result showed that, compared with DMSO (control) group, DZNep significantly increased the expression of miR-200c to about 2.1 times, inhibited ZEB1, ZEB2, and N-cadherin expressions, and activated E-cadherin expression; Also, DZNep decreased the protein expressions of EZH2, EED, SUZ12 and H3K27me3; Moreover, DZNep could inhibit MGC-803 cell invasive and migrative abilities, as well as MMP9 expression. These results suggest DZNep raises miR-200c expression to delay the invasion and migration of gastric carcinoma cells, and the underlying mechanisms involve the regulations of EMT-related proteins and polycomb repressive complex 2.

miR-21 improves the neurological outcome after traumatic brain injury in rats.

The expression levels of microRNAs (miRNAs) including miR-21, have been reported to change in response to traumatic brain injury (TBI), suggesting that they may influence the pathophysiological process in brain injury. To analyze the potential effect of miR-21 on neurological function after TBI, we employed the fluid percussion injury rat model and manipulated the expression level of miR-21 in brain using intracerebroventricular infusion of miR-21 agomir or antagomir. We found that upregulation of miR-21 level in brain conferred a better neurological outcome after TBI by improving long-term neurological function, alleviating brain edema and decreasing lesion volume. To further investigate the mechanism underlying this protective effect, we evaluated the impact of miR-21 on apoptosis and angiogenesis in brain after TBI. We found that miR-21 inhibited apoptosis and promoted angiogenesis through regulating the expression of apoptosis- and angiogenesis-related molecules. In addition, the expression of PTEN, a miR-21 target gene, was inhibited and Akt signaling was activated in the procedure. Taken together, these data indicate that miR-21 could be a potential therapeutic target for interventions after TBI.

RNA-seq of 272 gliomas revealed a novel, recurrent PTPRZ1-MET fusion transcript in secondary glioblastomas.

Studies of gene rearrangements and the consequent oncogenic fusion proteins have laid the foundation for targeted cancer therapy. To identify oncogenic fusions associated with glioma progression, we catalogued fusion transcripts by RNA-seq of 272 gliomas. Fusion transcripts were more frequently found in high-grade gliomas, in the classical subtype of gliomas, and in gliomas treated with radiation/temozolomide. Sixty-seven in-frame fusion transcripts were identified, including three recurrent fusion transcripts: FGFR3-TACC3, RNF213-SLC26A11, and PTPRZ1-MET (ZM). Interestingly, the ZM fusion was found only in grade III astrocytomas (1/13; 7.7%) or secondary GBMs (sGBMs, 3/20; 15.0%). In an independent cohort of sGBMs, the ZM fusion was found in three of 20 (15%) specimens. Genomic analysis revealed that the fusion arose from translocation events involving introns 3 or 8 of PTPRZ and intron 1 of MET. ZM fusion transcripts were found in GBMs irrespective of isocitrate dehydrogenase 1 (IDH1) mutation status. sGBMs harboring ZM fusion showed higher expression of genes required for PIK3CA signaling and lowered expression of genes that suppressed RB1 or TP53 function. Expression of the ZM fusion was mutually exclusive with EGFR overexpression in sGBMs. Exogenous expression of the ZM fusion in the U87MG glioblastoma line enhanced cell migration and invasion. Clinically, patients afflicted with ZM fusion harboring glioblastomas survived poorly relative to those afflicted with non-ZM-harboring sGBMs (P < 0.001). Our study profiles the shifting RNA landscape of gliomas during progression and reveled ZM as a novel, recurrent fusion transcript in sGBMs.

BASI, a potent small molecular inhibitor, inhibits glioblastoma progression by targeting microRNA-mediated ß-catenin signaling.

BACKGROUND AND AIMS: The nuclear localization of ß-catenin, a mediator of canonical Wnt signaling, has been indicated in a variety of cancers and is frequently related to tumor progression and metastasis. Therefore, targeting ß-catenin is an attractive therapeutic strategy for cancers. METHODS: Herein, we identified a natural, small molecule inhibitor of ß-catenin signaling, BASI, and evaluated its therapeutic efficacy both in vitro and in orthotopic mouse models of glioma. RESULTS: BASI significantly suppressed proliferation and invasion and induced apoptosis in glioblastoma cells and resulted in the remarkable attenuation of orthotopic tumor growth in vivo. Furthermore, we found that BASI altered the expression of several microRNAs, which mediated the posttranscriptional silencing of ß-catenin expression either directly or indirectly through a von Hippel-Lindau (VHL)-mediated ß-catenin degradation pattern. CONCLUSIONS: Taken together, our findings offer preclinical validation of BASI as a promising new type of ß-catenin inhibitor with a mechanism of inhibition that has broad potential for the improved treatment of glioblastoma.

MicroRNA-566 activates EGFR signaling and its inhibition sensitizes glioblastoma cells to nimotuzumab.

BACKGROUND: Epidermal growth factor receptor (EGFR) is amplified in 40% of human glioblastomas. However, most glioblastoma patients respond poorly to anti-EGFR therapy. MicroRNAs can function as either oncogenes or tumor suppressor genes, and have been shown to play an important role in cancer cell proliferation, invasion and apoptosis. Whether microRNAs can impact the therapeutic effects of EGFR inhibitors in glioblastoma is unknown. METHODS: miR-566 expression levels were detected in glioma cell lines, using real-time quantitative RT-PCR (qRT-PCR). Luciferase reporter assays and Western blots were used to validate VHL as a direct target gene of miR-566. Cell proliferation, invasion, cell cycle distribution and apoptosis were also examined to confirm whether miR-566 inhibition could sensitize anti-EGFR therapy. RESULTS: In this study, we demonstrated that miR-566 is up-regulated in human glioma cell lines and inhibition of miR-566 decreased the activity of the EGFR pathway. Lentiviral mediated inhibition of miR-566 in glioblastoma cell lines significantly inhibited cell proliferation and invasion and led to cell cycle arrest in the G0/G1 phase. In addition, we identified von Hippel-Lindau (VHL) as a novel functional target of miR-566. VHL regulates the formation of the ß-catenin/hypoxia-inducible factors-1α complex under miR-566 regulation. CONCLUSIONS: miR-566 activated EGFR signaling and its inhibition sensitized glioblastoma cells to anti-EGFR therapy.