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Project description:Multiple myeloma (MM) is a hematological malignancy caused by accumulation of abnormal clonal plasma cells. Despite the recent development of novel therapies, relapse of MM eventually occurs due to a remaining population of drug-resistant myeloma stem cells. Side population (SP) cells exhibit cancer stem cell-like characteristics in MM; thus targeting these cells is a promising strategy to completely cure this malignancy. Here, we showed that SP cells expressed higher levels of enhancer of zeste (EZH) 1 and EZH2, which encode the catalytic subunits of Polycomb repressive complex 2 (PRC2), than non-SP cells, suggesting that EZH1/2 are both potential therapeutic targets to eradicate myeloma stem cells. A novel EZH1/2 dual inhibitor, OR-S1, effectively eradicated SP cells and had a greater antitumor effect than a selective EZH2 inhibitor in vitro and in vivo, including in a patient-derived xenograft model. Moreover, long-term continuous administration of OR-S1 completely cured mice bearing orthotopic xenografts. Additionally, PRC2 directly regulated WNT signaling, and over-activation of this signaling induced by dual inhibition of EZH1/2 eradicated myeloma stem cells. Our results demonstrate that dual inhibition of EZH1/2 is a promising therapeutic approach to eradicate myeloma stem cells, leading to significant advances in the treatment of MM.
2019-01-25 | GSE109673 | GEO
Project description:Multiple myeloma (MM) is a hematological malignancy caused by accumulation of abnormal clonal plasma cells. Despite the recent development of novel therapies, relapse of MM eventually occurs due to a remaining population of drug-resistant myeloma stem cells. Side population (SP) cells exhibit cancer stem cell-like characteristics in MM; thus targeting these cells is a promising strategy to completely cure this malignancy. Here, we showed that SP cells expressed higher levels of enhancer of zeste (EZH) 1 and EZH2, which encode the catalytic subunits of Polycomb repressive complex 2 (PRC2), than non-SP cells, suggesting that EZH1/2 are both potential therapeutic targets to eradicate myeloma stem cells. A novel EZH1/2 dual inhibitor, OR-S1, effectively eradicated SP cells and had a greater antitumor effect than a selective EZH2 inhibitor in vitro and in vivo, including in a patient-derived xenograft model. Moreover, long-term continuous administration of OR-S1 completely cured mice bearing orthotopic xenografts. Additionally, PRC2 directly regulated WNT signaling, and over-activation of this signaling induced by dual inhibition of EZH1/2 eradicated myeloma stem cells. Our results demonstrate that dual inhibition of EZH1/2 is a promising therapeutic approach to eradicate myeloma stem cells, leading to significant advances in the treatment of MM.
2019-01-25 | GSE109674 | GEO
Project description:Dual inhibition of EZH1/2 depletes stem cells and over-activates WNT signaling in multiple myeloma
| PRJNA431632 | ENA
Project description:Dual inhibition of EZH1/2 depletes stem cells and over-activates WNT signaling in multiple myeloma [ChIP-seq]
| PRJNA431631 | ENA
Project description:Dual inhibition of EZH1/2 depletes stem cells and over-activates WNT signaling in multiple myeloma [RNA-seq]
| PRJNA431630 | ENA
Project description:Multiple myeloma (MM) is an incurable hematological malignancy caused by accumulation of abnormal clonal plasma cells. Despite the recent development of novel therapies, relapse of MM eventually occurs as a result of a remaining population of drug-resistant myeloma stem cells. Side population (SP) cells show cancer stem cell-like characteristics in MM; thus, targeting these cells is a promising strategy to completely cure this malignancy. Herein, we showed that SP cells expressed higher levels of enhancer of zeste homolog (EZH) 1 and EZH2, which encode the catalytic subunits of Polycomb repressive complex 2 (PRC2), than non-SP cells, suggesting that EZH1 as well as EZH2 contributes to the stemness maintenance of the MM cells and that targeting both EZH1/2 is potentially a significant therapeutic approach for eradicating myeloma stem cells. A novel orally bioavailable EZH1/2 dual inhibitor, OR-S1, effectively eradicated SP cells and had a greater antitumor effect than a selective EZH2 inhibitor in vitro and in vivo, including a unique patient-derived xenograft model. Moreover, long-term continuous dosing of OR-S1 completely cured mice bearing orthotopic xenografts. Additionally, PRC2 directly regulated WNT signaling in MM, and overactivation of this signaling induced by dual inhibition of EZH1/2 eradicated myeloma stem cells and negatively affected tumorigenesis, suggesting that repression of WNT signaling by PRC2 plays an important role in stemness maintenance of MM cells. Our results show the role of EZH1/2 in the maintenance of myeloma stem cells and provide a preclinical rationale for therapeutic application of OR-S1, leading to significant advances in the treatment of MM.
| S-EPMC6317945 | biostudies-literature
Project description:The unrestrained growth of tumor cells is generally attributed to mutations in essential growth control genes, but tumor cells are also influenced by signals from the environment. In multiple myeloma (MM), the factors and signals coming from the bone marrow microenvironment are possibly even essential for the growth of the tumor cells. As targets for intervention, these signals may be equally important as mutated oncogenes. Given their oncogenic potential, WNT signals form a class of paracrine growth factors that could act to influence MM cell growth. In this paper, we report that MM cells have hallmarks of active WNT signaling, whereas the cells have not undergone detectable mutations in WNT signaling genes such as adenomatous polyposis coli and beta-catenin (CTNNB1). We show that the malignant MM plasma cells overexpress beta-catenin, including its N-terminally unphosphorylated form, suggesting active beta-catenin/T cell factor-mediated transcription. Further accumulation and nuclear localization of beta-catenin, and/or increased cell proliferation, was achieved by stimulation of WNT signaling with either Wnt3a, LiCl, or the constitutively active S33Y mutant of beta-catenin. In contrast, by blocking WNT signaling by dominant-negative T cell factor, we can interfere with the growth of MM cells. We therefore suggest that MM cells are dependent on an active WNT signal, which may have important implications for the management of this incurable form of cancer.
| S-EPMC395933 | biostudies-literature
Project description:Purpose: EZH2 and EZH1, the catalytic components of polycomb repressive complex 2 (PRC2), trigger trimethylation of H3K27 (H3K27me3) to repress the transcription of target genes and are implicated in the pathogenesis of various cancers including multiple myeloma and prostate cancer. Here, we investigated the preclinical effects of UNC1999, a dual inhibitor of EZH2 and EZH1, in combination with proteasome inhibitors on multiple myeloma and prostate cancer.Experimental Design:In vitro and in vivo efficacy of UNC1999 and the combination with proteasome inhibitors was evaluated in multiple myeloma cell lines, primary patient cells, and in a xenograft model. RNA-seq and ChIP-seq were performed to uncover the targets of UNC1999 in multiple myeloma. The efficacy of the combination therapy was validated in prostate cancer cell lines.Results: Proteasome inhibitors repressed EZH2 transcription via abrogation of the RB-E2F pathway, thereby sensitizing EZH2-dependent multiple myeloma cells to EZH1 inhibition by UNC1999. Correspondingly, combination of proteasome inhibitors with UNC1999, but not with an EZH2-specific inhibitor, induced synergistic antimyeloma activity in vitro Bortezomib combined with UNC1999 remarkably inhibited the growth of myeloma cells in vivo Comprehensive analyses revealed several direct targets of UNC1999 including the tumor suppressor gene NR4A1 Derepression of NR4A1 by UNC1999 resulted in suppression of MYC, which was enhanced by the combination with bortezomib, suggesting the cooperative blockade of PRC2 function. Notably, this combination also exhibited strong synergy in prostate cancer cells.Conclusions: Our results identify dual inhibition of EZH2 and EZH1 together with proteasome inhibition as a promising epigenetics-based therapy for PRC2-dependent cancers. Clin Cancer Res; 23(16); 4817-30. ©2017 AACR.
| S-EPMC5562278 | biostudies-literature
Project description:Easily developed chemoresistance is a major characteristic of multiple myeloma (MM) and the main obstacle in curing MM in the clinic, but the key regulators have not been fully identified. In the current study, we find that PPFIA Binding Protein 1 (PPFIBP1) is highly expressed in the plasma cells from MM patients, and higher PPFIBP1 expression predicts poorer outcomes. PPFPIBP1 enhances chemoresistance of MM cells to the treatment of bortezomib (BTZ), a proteasome inhibitor, and manipulation of PPFPIBP1 can alter chemosensitivity of MM cells to BTZ. Mechanistic studies reveal that PPFPIBP1 directly binds and stabilizes RelA, promotes the cyto-nuclear translocation of RelA, and activates NF-κB signaling pathway. Targeting PPFPIBP1 in a xenograft mouse model of MM prohibits tumor growth and prolongs overall survival of mice. Taken together, our findings suggest that PPFIBP1 is a crucial regulator of chemoresistance to PIs in MM cells, and shed light on developing therapeutic strategies to overcome chemoresistance by targeting PPFIBP1.
| S-EPMC10458954 | biostudies-literature
Project description:Multiple myeloma (MM) is a haematological malignancy being characterized by clonal plasma cell proliferation in the bone marrow. Targeting the proteasome with specific inhibitors (PIs) has been proven a promising therapeutic strategy and PIs have been approved for the treatment of MM and mantle-cell lymphoma; yet, while outcome has improved, most patients inevitably relapse. As relapse refers to MM cells that survive therapy, we sought to identify the molecular responses induced in MM cells after non-lethal proteasome inhibition. By using bortezomib (BTZ), epoxomicin (EPOX; a carfilzomib-like PI) and three PIs, namely Rub999, PR671A and Rub1024 that target each of the three proteasome peptidases, we found that only BTZ and EPOX are toxic in MM cells at low concentrations. Phosphoproteomic profiling after treatment of MM cells with non-lethal (IC10 ) doses of the PIs revealed inhibitor- and cell type-specific readouts, being marked by the activation of tumorigenic STAT3 and STAT6. Consistently, cytokine/chemokine profiling revealed the increased secretion of immunosuppressive pro-tumorigenic cytokines (IL6 and IL8), along with the inhibition of potent T cell chemoattractant chemokines (CXCL10). These findings indicate that MM cells that survive treatment with therapeutic PIs shape a pro-tumorigenic immunosuppressive cellular and secretory bone marrow microenvironment that enables malignancy to relapse.
| S-EPMC6850931 | biostudies-literature