RETRACTED ARTICLE: Dissecting the role of novel EZH2 inhibitors in primary glioblastoma cell cultures: effects on proliferation, epithelial-mesenchymal transition, migration, and on the pro-inflammatory phenotype

Abstract

BackgroundGlioblastoma (GBM) is the most lethal and aggressive malignant primary brain tumor in adults. After surgical resection of the tumor, the patient typically should be subjected to chemotherapy (temozolomide, TMZ) and concomitant radiotherapy. Since the TMZ treatment does not lead to complete remission and often develops resistance, the identification of efficacious therapeutics is strongly to pursue. Among the epigenetic players, the H3K27 methyltransferase (MT) EZH2 (enhancer of zeste homologue 2) has been found overexpressed or mutated in several human cancers including gliomas, and its overexpression is associated with poor outcome in GBM. Two EZH2 inhibitors (EZH2i), UNC1999 and GSK343, suppressed GBM growth in vitro and in vivo indicating that EZH2i can be potential drugs against GBM.ResultsTwo new EZH2i, MC4040 and MC4041, were designed, prepared, and tested by us to determine their effects in primary GBM cell cultures. MC4040 and MC4041 displayed single-digit micromolar inhibition of EZH2, 10-fold less potency against EZH1, and no activity towards other MTs. In primary GBM cells as well as in U-87 GBM cells, the two compounds reduced H3K27me3 levels, and dose- and time-dependently impaired GBM cell viability without inducing apoptosis and arresting the cell cycle in the G0/G1 phase, with increased p21 and p27 levels. In combination with TMZ, MC4040 and MC4041 displayed stronger, but not additive, effects on cell viability. The potent clinical candidate as EZH2i tazemetostat, alone or in combination with TMZ, exhibited a similar potency of inhibition of GBM cell growth when compared to MC4040 and MC4041. At the molecular level, MC4040 and MC4041 reduced the VEGFR1/VEGF expression, reversed the epithelial-mesenchymal transition (EMT), and hampered cell migration and invasion attenuating the cancer malignant phenotype. Treatment of GBM cells with MC4040 and MC4041 also impaired the GBM pro-inflammatory phenotype, with a significant decrease of TGF-β, TNF-α, and IL-6, joined to an increase of the anti-inflammatory cytokine IL-10.ConclusionsThe two novel EZH2i MC4040 and MC4041 impaired primary GBM cell viability, showing even stronger effects in combination with TMZ. They also weakened the aggressive malignant phenotype by reducing angiogenesis, EMT, cell migration/invasion and inflammation, thus they may be considered potential candidates against GBM also for combination therapies.

Long non-coding RNA HAL suppresses the migration and invasion of serous ovarian cancer by inhibiting EMT signaling pathway

“…At present, the difficulty of multiple tumor treatments is the resistance of relapse and chemotherapy. Studies have pointed out that EMT signaling pathway is an important mechanism for the development of ovarian tumor [5,29]. Studies have shown that the BMP4-mediated signaling pathway led to morphological changes in tumor cells and enhanced cell adhesion, migration, and invasion by inducing EMT [30].…”

MiR-33a functions as a tumor suppressor in triple-negative breast cancer by targeting EZH2

“…Tazemetostat, an EZH2 inhibitor, has been approved for treating epithelioid sarcoma, and it is the first EZH2 inhibitor approved by FDA [47]. Other EZH2 inhibitor, GSK343 and GSK236, were also reported to inhibit tumor progression in various cancer, such as glioblastoma [48], head and neck cancer, [49] and breast cancer [50]. Our in vitro study confirmed the regulatory mechanism of miR-33a/EZH2 cascade in TNBC progression, thus, more investigation of the effects of miR-33a and EZH2 on tumor growth and metastasis in vivo is needed.…”

Mesenchymal Transformation: The Rosetta Stone of Glioblastoma Pathogenesis and Therapy Resistance

“…The histone-lysine N-methyltransferase enzyme EZH2 (enhancer of zeste homolog 2), which catalyzes the addition of methyl groups to histone H3 at lysine 27 thereby silencing gene function, plays an important role in glioma progression. [64,65] EZH2 inhibitor GSK343 upregulates EZH2 target genes, leading to suppression of GBM growth and reversing PMT by controlling Ncadherin and vimentin expression. [66] Vinchure et al demonstrated that epigenetic control of miR-490-3p by EZH2 regulates PMT through TGIF2 signaling.…”