RESUMO
Large-scale heterozygous deletions are a hallmark of cancer genomes. The concomitant loss of multiple genes creates vulnerabilities that are impossible to reveal through the study of individual genes. To delineate the functional outcome of chromosome 8p loss of heterozygosity (LOH), a common aberration in breast cancer, we modeled 8p LOH using TALEN-based genomic engineering. 8p LOH alters fatty acid and ceramide metabolism. The shift in lipid metabolism triggers invasiveness and confers tumor growth under stress conditions due to increased autophagy. The resistance of 8p-deleted cells to chemotherapeutic drugs concurs with poorer survival rates of breast cancer patients harboring an 8p LOH. The autophagy dependency of 8p-deleted cells provides the rational basis for treatment of 8p LOH tumors with autophagy inhibitors.
Assuntos
Neoplasias da Mama/genética , Deleção Cromossômica , Cromossomos Humanos Par 8/genética , Metabolismo dos Lipídeos/genética , Antineoplásicos/farmacologia , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Hipóxia Celular , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Transformação Celular Neoplásica/efeitos dos fármacos , Transformação Celular Neoplásica/genética , Progressão da Doença , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Hibridização in Situ Fluorescente/métodos , Estimativa de Kaplan-Meier , Metabolismo dos Lipídeos/efeitos dos fármacos , Análise Multivariada , Prognóstico , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Esferoides Celulares/efeitos dos fármacos , Esferoides Celulares/metabolismoRESUMO
The complex of the yeast Lsm1p-7p proteins with Pat1p is an important mRNA decay factor that is involved in translational shutdown of deadenylated mRNAs and thus prepares these mRNAs for degradation. While the Lsm proteins are highly conserved, there is no unique mammalian homolog of Pat1p. To identify proteins that interact with human LSm1, we developed a novel immunoprecipitation technique that yields virtually pure immunocomplexes. Mass-spec analysis therefore identifies mostly true positives, avoiding tedious functional screening. The method unambiguously identified the Pat1p homolog in HeLa cells, Pat1b. When targeted to a reporter mRNA, Pat1b represses gene expression by inducing deadenylation of the mRNAs. This demonstrates that Pat1b, unlike yPat1p, acts as an mRNA-specific deadenylation factor, highlighting the emerging importance of deadenylation in the mRNA regulation of higher eukaryotes.
