EZH2-regulated PARP-1 Expression is a Likely Mechanism for the Chemoresistance of Gliomas to Temozolomide.

BACKGROUND: Chemoresistance in gliomas accounts for the major cause of tumor progress and recurrence during comprehensive treatment with alkylating agents including temozolomide (TMZ). The oncogenic role of Enhancer of zeste homolog 2 (EZH2) has been identified in many solid malignancies including gliomas, though the accurate effect of EZH2 on chemotherapy resistance of gliomas has been elusive. OBJECTIVE: To elucidate the role of EHZ2 on TMZ resistance of gliomas and the molecular mechanisms. METHODS: Immunohistochemistry (IHC) and Reverse transcription-quantitative (RT-q) PCR, and western blot assay were performed for expressional analysis. Cell Counting Kit-8 (CCK-8) assay was applied to determine the TMZ sensitivity. EZH2-silencing lentivirus was generated for mechanic study. RESULTS: EZH2 was overexpressed in gliomas both at the transcriptional and protein levels. EZH2 level in glioma cell lines was positively correlated with resistance to TMZ, represented by the 50% inhibition rate (IC50). Moreover, there was increased TMZ sensitivity in EZH2-inhibited glioma cells than in the control cells. Furthermore, we determined that PARP1 was a common molecule among the downregulated DNA repair proteins in both U251 and U87 glioma cell lines after EZH2 inhibition. Specifically, we observed a spontaneous increase of PARP1 expression with TMZ treatment and interestingly, the increase of PARP1 could be also reduced by EZH2 inhibition in the glioma cells. Finally, combined treatment with lentivirus-induced EZH2 inhibition and a PARP1 inhibitor dramatically enhanced TMZ cytotoxicity compared with either one alone. CONCLUSION: EZH2-PARP-1 signaling axis is possibly responsible for the chemoresistance of gliomas to TMZ. Simultaneously inhibiting these two genes may improve the outcome of TMZ chemotherapy.

Entrepreneurial Psychology and Motivation of Museum Cultural and Creative Product Development.

More students who majored in design should be led to be self-employment, as they can use their major advantages to lead cultural and creative industries of museums toward a more creative direction. Based on the present situation of self-employment of college students related to cultural and creative industries, developing patterns and structure of cultural and creative industries of museums are analyzed to study the practical requirement of development of creative and cultural products of museums on the students majored in design. College students and graduates (within 2 years) in design major of a college in Zhejiang province who have experience in starting a business are invited to make the questionnaire survey and to study the practical problems with motives and barriers of starting a business. After the investigation of the entrepreneurial status of cultural and creative entrepreneurs of college students, it is found that the third year is the peak period for students to choose entrepreneurship, followed by the end of the senior year. Only 36.8% of respondents are satisfied with the results of entrepreneurship, which reflects that entrepreneurs do face many obstacles in the actual process of entrepreneurship, mainly due to a lack of experience and funds. The motivation for students to stick to entrepreneurial activities mainly focuses on "obtaining personal wealth" and "realizing self-worth." In view of this situation, universities, society, and government can provide technical support and policy support to stimulate the entrepreneurial potential of cultural and creative entrepreneurs of college students, thus promoting the efficient development of museum cultural and creative industry.

P4HA2 Promotes Epithelial-to-Mesenchymal Transition and Glioma Malignancy through the Collagen-Dependent PI3K/AKT Pathway.

Prolyl-4-hydroxylase subunit 2 (P4HA2) is a member of collagen modification enzymes involved in the remodeling of the extracellular matrix (ECM). Mounting evidence has suggested that deregulation of P4HA2 is common in cancer. However, the role of P4HA2 in glioma remains unknown. The present study aimed to elucidate the expression pattern, oncogenic functions, and molecular mechanisms of P4HA2 in glioblastoma cells. The TCGA datasets and paraffin samples were used for examining the expressions of P4HA2. P4HA2-specific lentivirus was generated to assess its oncogenic functions. A P4HA2 enzyme inhibitor (DHB) and an AKT agonist (SC79) were utilized to study the mechanisms. As a result, we demonstrated that P4HA2 is overexpressed in glioma and inversely correlates with patient survival. Knockdown of P4HA2 inhibited proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT) like phenotype of glioma cells in vitro and suppressed tumor xenograft growth in vivo. Mechanistically, expressions of a series of collagen genes and of phosphorylated PI3K/AKT were downregulated by either P4HA2 silencing or inhibition of its prolyl hydroxylase. Finally, the inhibitory effects on the migration, invasion, and EMT-related molecules by P4HA2 knockdown were reversed by AKT activation with SC79. Our findings for the first time reveal that P4HA2 acts as an oncogenic molecule in glioma malignancy by regulating the expressions of collagens and the downstream PI3K/AKT signaling pathway.

Characterizing the molecular mechanisms of acquired temozolomide resistance in the U251 glioblastoma cell line by protein microarray.

Acquired chemoresistance refers to tumor cells gradually losing their sensitivity to anticancer drugs during the course of treatment, resulting in tumor progression or recurrence. This phenomenon, which has deleterious outcomes for the patient, has long been observed in patients with glioblastoma receiving temozolomide (TMZ)-based radiochemotherapy. Currently, the mechanisms for acquired TMZ chemoresistance are not fully understood. In the present study, a TMZ-resistant cell line U251R with a 4-fold 50% inhibition concentration compared with its TMZ-sensitive parent cell line was isolated by incremental long-time TMZ treatment in the human glioblastoma cell line U251. Fluorescence-activated cell sorting analysis indicated G2/M arrest and a lower proportion of cells in the S phase, accompanied by a decreased apoptosis rate in the U251R cell line compared with the parental U251 cell line. In addition, a sphere-formation assay indicated an increased self-renewal capacity in U251R cells. Furthermore, a high-throughput protein microarray unveiled more than 200 differentially expressed proteins as potential molecular targets accounting for acquired TMZ resistance. Subsequent bioinformatics analysis illustrated the molecular and signaling networks and revealed the central role of SRC. Immunoblotting and reverse-transcription quantitative polymerase chain reaction analysis further confirmed the expressional upregulation of SRC family kinases. Moreover, SRC knockdown led to partial reversal of TMZ resistance in the U251R cell line and sensitization in the U373 cell line. These data helped to develop a comprehensive understanding of survival strategies, particularly with respect to pro-stemness regulation, which could be potential targets for overcoming TMZ resistance.

FBW7 is associated with prognosis, inhibits malignancies and enhances temozolomide sensitivity in glioblastoma cells.

F-box and WD repeat domain-containing 7 (FBW7) is a SCF-type E3 ubiquitin ligase targeting a multitude of oncoproteins for degradation. Acting as one of the most important tumor suppressors, it is frequently inactivated in various tumors. In this study we aimed to evaluate the relationship of FBW7 with glioma pathology and prognosis, and examine its effect in glioma malignancies and temozolomide (TMZ)-based therapy. Clinical tissues and TCGA database analysis revealed that FBW7 expression was correlated inversely with glioma histology and positively with patient survival time. Lentivirus transfection-induced FBW7 overexpression significantly suppressed proliferation, invasion and migration of U251 and U373 cells, whereas knockdown of FBW7 by targeted shRNA promoted proliferation, invasion and migration of glioma cells. Most importantly, the expression level of FBW7 was found to affect the 50% inhibitory concentration (IC50) of U251 and the TMZ-resistant variant. Combining TMZ with FBW7 overexpression notably increased the cytotoxicity compared to TMZ treatment alone, which was conversely attenuated by FBW7 knockdown. Moreover, flow cytometry (FC) analysis showed overexpression of FBW7, TMZ or the combination-increased proportion of G2/M arrest and the apoptotic rate, whereas FBW7 inhibition reduced G2/M arrest and apoptosis in U251 cells. Finally, mechanistic study found that FBW7 overexpression downregulated Aurora B, Mcl1 and Notch1 levels in a time-dependent pattern and this expressional suppression was independent of TMZ. These findings collectively demonstrate the critical role of FBW7 as a prognostic factor and a potential target to overcome chemoresistance of glioblastoma.