RESUMO
Type I protein arginine methyltransferases (PRMTs) catalyze asymmetric dimethylation of arginines on proteins. Type I PRMTs and their substrates have been implicated in human cancers, suggesting inhibition of type I PRMTs may offer a therapeutic approach for oncology. The current report describes GSK3368715 (EPZ019997), a potent, reversible type I PRMT inhibitor with anti-tumor effects in human cancer models. Inhibition of PRMT5, the predominant type II PRMT, produces synergistic cancer cell growth inhibition when combined with GSK3368715. Interestingly, deletion of the methylthioadenosine phosphorylase gene (MTAP) results in accumulation of the metabolite 2-methylthioadenosine, an endogenous inhibitor of PRMT5, and correlates with sensitivity to GSK3368715 in cell lines. These data provide rationale to explore MTAP status as a biomarker strategy for patient selection.
Assuntos
Antineoplásicos/farmacologia , Inibidores Enzimáticos/farmacologia , Proteína-Arginina N-Metiltransferases/antagonistas & inibidores , Purina-Núcleosídeo Fosforilase/deficiência , Processamento Alternativo , Antineoplásicos/química , Biomarcadores , Linhagem Celular Tumoral , Sinergismo Farmacológico , Inibidores Enzimáticos/química , Humanos , Metilação , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Ligação Proteica , Proteína-Arginina N-Metiltransferases/química , Especificidade por SubstratoRESUMO
CARM1 is an arginine methyltransferase with diverse histone and non-histone substrates implicated in the regulation of cellular processes including transcriptional co-activation and RNA processing. CARM1 overexpression has been reported in multiple cancer types and has been shown to modulate oncogenic pathways in in vitro studies. Detailed understanding of the mechanism of action of CARM1 in oncogenesis has been limited by a lack of selective tool compounds, particularly for in vivo studies. We describe the identification and characterization of, to our knowledge, the first potent and selective inhibitor of CARM1 that exhibits anti-proliferative effects both in vitro and in vivo and, to our knowledge, the first demonstration of a role for CARM1 in multiple myeloma (MM). EZM2302 (GSK3359088) is an inhibitor of CARM1 enzymatic activity in biochemical assays (IC50 = 6 nM) with broad selectivity against other histone methyltransferases. Treatment of MM cell lines with EZM2302 leads to inhibition of PABP1 and SMB methylation and cell stasis with IC50 values in the nanomolar range. Oral dosing of EZM2302 demonstrates dose-dependent in vivo CARM1 inhibition and anti-tumor activity in an MM xenograft model. EZM2302 is a validated chemical probe suitable for further understanding the biological role CARM1 plays in cancer and other diseases.
Assuntos
Antineoplásicos/uso terapêutico , Proteínas Adaptadoras de Sinalização CARD/antagonistas & inibidores , Inibidores Enzimáticos/uso terapêutico , Guanilato Ciclase/antagonistas & inibidores , Isoxazóis/uso terapêutico , Mieloma Múltiplo/tratamento farmacológico , Pirimidinas/uso terapêutico , Compostos de Espiro/uso terapêutico , Animais , Antineoplásicos/farmacocinética , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacocinética , Humanos , Técnicas In Vitro , Isoxazóis/farmacocinética , Masculino , Camundongos , Transplante de Neoplasias , Pirimidinas/farmacocinética , Ratos Sprague-Dawley , Compostos de Espiro/farmacocinéticaRESUMO
The EZH2 small-molecule inhibitor tazemetostat (EPZ-6438) is currently being evaluated in phase II clinical trials for the treatment of non-Hodgkin lymphoma (NHL). We have previously shown that EZH2 inhibitors display an antiproliferative effect in multiple preclinical models of NHL, and that models bearing gain-of-function mutations in EZH2 were consistently more sensitive to EZH2 inhibition than lymphomas with wild-type (WT) EZH2 Here, we demonstrate that cell lines bearing EZH2 mutations show a cytotoxic response, while cell lines with WT-EZH2 show a cytostatic response and only tumor growth inhibition without regression in a xenograft model. Previous work has demonstrated that cotreatment with tazemetostat and glucocorticoid receptor agonists lead to a synergistic antiproliferative effect in both mutant and wild-type backgrounds, which may provide clues to the mechanism of action of EZH2 inhibition in WT-EZH2 models. Multiple agents that inhibit the B-cell receptor pathway (e.g., ibrutinib) were found to have synergistic benefit when combined with tazemetostat in both mutant and WT-EZH2 backgrounds of diffuse large B-cell lymphomas (DLBCL). The relationship between B-cell activation and EZH2 inhibition is consistent with the proposed role of EZH2 in B-cell maturation. To further support this, we observe that cell lines treated with tazemetostat show an increase in the B-cell maturation regulator, PRDM1/BLIMP1, and gene signatures corresponding to more advanced stages of maturation. These findings suggest that EZH2 inhibition in both mutant and wild-type backgrounds leads to increased B-cell maturation and a greater dependence on B-cell activation signaling. Mol Cancer Ther; 16(11); 2586-97. ©2017 AACR.
Assuntos
Benzamidas/administração & dosagem , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Pirazóis/administração & dosagem , Piridonas/administração & dosagem , Pirimidinas/administração & dosagem , Adenina/análogos & derivados , Animais , Linfócitos B/efeitos dos fármacos , Compostos de Bifenilo , Proliferação de Células/efeitos dos fármacos , Metilação de DNA/efeitos dos fármacos , Sinergismo Farmacológico , Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Linfoma Difuso de Grandes Células B/genética , Linfoma Difuso de Grandes Células B/patologia , Camundongos , Morfolinas , Mutação , Piperidinas , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The SWI/SNF complex is a major regulator of gene expression and is increasingly thought to play an important role in human cancer, as evidenced by the high frequency of subunit mutations across virtually all cancer types. We previously reported that in preclinical models, malignant rhabdoid tumors, which are deficient in the SWI/SNF core component INI1 (SMARCB1), are selectively killed by inhibitors of the H3K27 histone methyltransferase EZH2. Given the demonstrated antagonistic activities of the SWI/SNF complex and the EZH2-containing PRC2 complex, we investigated whether additional cancers with SWI/SNF mutations are sensitive to selective EZH2 inhibition. It has been recently reported that ovarian cancers with dual loss of the redundant SWI/SNF components SMARCA4 and SMARCA2 are characteristic of a rare rhabdoid-like subtype known as small-cell carcinoma of the ovary hypercalcemic type (SCCOHT). Here, we provide evidence that a subset of commonly used ovarian carcinoma cell lines were misdiagnosed and instead were derived from a SCCOHT tumor. We also demonstrate that tazemetostat, a potent and selective EZH2 inhibitor currently in phase II clinical trials, induces potent antiproliferative and antitumor effects in SCCOHT cell lines and xenografts deficient in both SMARCA2 and SMARCA4. These results exemplify an additional class of rhabdoid-like tumors that are dependent on EZH2 activity for survival. Mol Cancer Ther; 16(5); 850-60. ©2017 AACR.
Assuntos
Carcinoma de Células Pequenas/tratamento farmacológico , DNA Helicases/genética , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Proteínas Nucleares/genética , Neoplasias Ovarianas/tratamento farmacológico , Tumor Rabdoide/tratamento farmacológico , Fatores de Transcrição/genética , Animais , Carcinoma de Células Pequenas/diagnóstico , Carcinoma de Células Pequenas/genética , Carcinoma de Células Pequenas/patologia , Linhagem Celular Tumoral , Proteínas Cromossômicas não Histona/genética , Diagnóstico Diferencial , Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Histona-Lisina N-Metiltransferase/genética , Humanos , Hipercalcemia/diagnóstico , Hipercalcemia/tratamento farmacológico , Hipercalcemia/genética , Hipercalcemia/patologia , Camundongos , Mutação , Neoplasias Ovarianas/diagnóstico , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Tumor Rabdoide/diagnóstico , Tumor Rabdoide/genética , Tumor Rabdoide/patologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
A novel aryl pyrazole series of arginine methyltransferase inhibitors has been identified. Synthesis of analogues within this series yielded the first potent, selective, small molecule PRMT6 inhibitor tool compound, EPZ020411. PRMT6 overexpression has been reported in several cancer types suggesting that inhibition of PRMT6 activity may have therapeutic utility. Identification of EPZ020411 provides the field with the first small molecule tool compound for target validation studies. EPZ020411 shows good bioavailability following subcutaneous dosing in rats making it a suitable tool for in vivo studies.
RESUMO
Protein arginine methyltransferase-5 (PRMT5) is reported to have a role in diverse cellular processes, including tumorigenesis, and its overexpression is observed in cell lines and primary patient samples derived from lymphomas, particularly mantle cell lymphoma (MCL). Here we describe the identification and characterization of a potent and selective inhibitor of PRMT5 with antiproliferative effects in both in vitro and in vivo models of MCL. EPZ015666 (GSK3235025) is an orally available inhibitor of PRMT5 enzymatic activity in biochemical assays with a half-maximal inhibitory concentration (IC50) of 22 nM and broad selectivity against a panel of other histone methyltransferases. Treatment of MCL cell lines with EPZ015666 led to inhibition of SmD3 methylation and cell death, with IC50 values in the nanomolar range. Oral dosing with EPZ015666 demonstrated dose-dependent antitumor activity in multiple MCL xenograft models. EPZ015666 represents a validated chemical probe for further study of PRMT5 biology and arginine methylation in cancer and other diseases.