RESUMO
Despite an increasing number of approved therapies, multiple myeloma (MM) remains an incurable disease and only a small number of patients achieve prolonged disease control. Some genes have been linked with response to commonly used anti-MM compounds, including immunomodulators (IMiDs) and proteasome inhibitors (PIs). In this manuscript, we demonstrate an increased incidence of acquired proteasomal subunit mutations in relapsed MM compared to newly diagnosed disease, underpinning a potential role of point mutations in the clonal evolution of MM. Furthermore, we are first to present and functionally characterize four somatic PSMB5 mutations from primary MM cells identified in a patient under prolonged proteasome inhibition, with three of them affecting the PI-binding pocket S1. We confirm resistance induction through missense mutations not only to Bortezomib, but also, in variable extent, to the next-generation PIs Carfilzomib and Ixazomib. In addition, a negative impact on the proteasome activity is assessed, providing a potential explanation for later therapy-induced eradication of the affected tumor subclones in this patient.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Biomarcadores Tumorais/genética , Resistencia a Medicamentos Antineoplásicos/genética , Mieloma Múltiplo/genética , Mutação , Recidiva Local de Neoplasia/genética , Complexo de Endopeptidases do Proteassoma/genética , Biomarcadores Tumorais/metabolismo , Compostos de Boro/administração & dosagem , Bortezomib/administração & dosagem , Estudos de Coortes , Feminino , Seguimentos , Regulação Neoplásica da Expressão Gênica , Glicina/administração & dosagem , Glicina/análogos & derivados , Humanos , Masculino , Pessoa de Meia-Idade , Mieloma Múltiplo/tratamento farmacológico , Mieloma Múltiplo/patologia , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/patologia , Oligopeptídeos/administração & dosagem , Prognóstico , Complexo de Endopeptidases do Proteassoma/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/metabolismo , Taxa de SobrevidaRESUMO
shRNA expression is an established technique to transiently or permanently deplete cells of a particular mRNA/protein. In functional analyses of oncogenic pathways it can thus be used as an alternative to pharmacologic inhibitors, or as a means to address otherwise undruggable targets. Here we describe and functionally validate a simple reiterative cloning system to generate concatenated multi-shRNA expression plasmids. The multi-shRNA expression cassette can eventually be subcloned into any suitably designed vector for the stable transfection of cells, here tested with derivatives of the Sleeping Beauty transposon vector for stable transfection of multiple myeloma cell lines at the lowest biosafety level. We finally test inducible versions of such multi-cassette knockdown vectors and show their efficacy for the induced concerted knockdown of all four components of the MEK/MAPK-module in the Ras/MAPK pathway. The described vector system(s) should be useful for functional knockdown analyses in a wide array of cell line models.