RESUMO
Maintenance of phenotypic heterogeneity within cell populations is an evolutionarily conserved mechanism that underlies population survival upon stressful exposures. We show that the genomes of a cancer cell subpopulation that survives treatment with otherwise lethal drugs, the drug-tolerant persisters (DTPs), exhibit a repressed chromatin state characterized by increased methylation of histone H3 lysines 9 and 27 (H3K9 and H3K27). We also show that survival of DTPs is, in part, maintained by regulators of H3K9me3-mediated heterochromatin formation and that the observed increase in H3K9me3 in DTPs is most prominent over long interspersed repeat element 1 (LINE-1). Disruption of the repressive chromatin over LINE-1 elements in DTPs results in DTP ablation, which is partially rescued by reducing LINE-1 expression or function.
Assuntos
Cromatina/genética , Resistencia a Medicamentos Antineoplásicos/genética , Repressão Epigenética/efeitos dos fármacos , Elementos Nucleotídeos Longos e Dispersos/genética , Neoplasias/patologia , Animais , Antineoplásicos/farmacologia , Regulação Neoplásica da Expressão Gênica , Instabilidade Genômica/efeitos dos fármacos , Histona-Lisina N-Metiltransferase/metabolismo , Histonas/metabolismo , Humanos , Metilação , Camundongos , Camundongos Nus , Camundongos SCID , Neoplasias/tratamento farmacológico , Neoplasias/genética , Estresse Fisiológico , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Although standard chemotherapies are commonly used to treat most types of solid tumors, such treatment often results in inadequate response to, or relapse after, therapy. This is particularly relevant for lung cancer because most patients are diagnosed with advanced-stage disease and are treated with frontline chemotherapy. By studying the residual tumor cells that remain after chemotherapy in several in vivo non-small cell lung cancer models, we found that these cells have increased levels of human epidermal growth factor receptor (HER) signaling due, in part, to the enrichment of a preexisting NRG1(HI) subpopulation. Neuregulin 1 (NRG1) signaling in these models can be mediated by either the HER3 or HER4 receptor, resulting in the differential activation of downstream effectors. Inhibition of NRG1 signaling inhibits primary tumor growth and enhances the magnitude and duration of the response to chemotherapy. Moreover, we show that inhibition of ligand-mediated Her4 signaling impedes disease relapse in cases where NRG1 inhibition is insufficient. These findings demonstrate that ligand-dependent Her4 signaling plays an important role in disease relapse.