RESUMEN
Aneuploidies-whole-chromosome or whole-arm imbalances-are the most prevalent alteration in cancer genomes1,2. However, it is still debated whether their prevalence is due to selection or ease of generation as passenger events1,2. Here we developed a method, BISCUT, that identifies loci subject to fitness advantages or disadvantages by interrogating length distributions of telomere- or centromere-bounded copy-number events. These loci were significantly enriched for known cancer driver genes, including genes not detected through analysis of focal copy-number events, and were often lineage specific. BISCUT identified the helicase-encoding gene WRN as a haploinsufficient tumour-suppressor gene on chromosome 8p, which is supported by several lines of evidence. We also formally quantified the role of selection and mechanical biases in driving aneuploidy, finding that rates of arm-level copy-number alterations are most highly correlated with their effects on cellular fitness1,2. These results provide insight into the driving forces behind aneuploidy and its contribution to tumorigenesis.
Asunto(s)
Aneuploidia , Transformación Celular Neoplásica , Neoplasias , Humanos , Transformación Celular Neoplásica/genética , Variaciones en el Número de Copia de ADN/genética , Neoplasias/genética , Neoplasias/patología , Oncogenes/genética , Telómero/genética , Centrómero/genética , Linaje de la Célula , Cromosomas Humanos Par 8/genética , Genes Supresores de TumorRESUMEN
Velcrin compounds kill cancer cells expressing high levels of phosphodiesterase 3A (PDE3A) and Schlafen family member 12 (SLFN12) by inducing complex formation between these two proteins, but the mechanism of cancer cell killing by the PDE3A-SLFN12 complex is not fully understood. Here, we report that the physiological substrate of SLFN12 RNase is tRNALeu(TAA). SLFN12 selectively digests tRNALeu(TAA), and velcrin treatment promotes the cleavage of tRNALeu(TAA) by inducing PDE3A-SLFN12 complex formation in vitro. We found that distinct sequences in the variable loop and acceptor stem of tRNALeu(TAA) are required for substrate digestion. Velcrin treatment of sensitive cells results in downregulation of tRNALeu(TAA), ribosome pausing at Leu-TTA codons and global inhibition of protein synthesis. Velcrin-induced cleavage of tRNALeu(TAA) by SLFN12 and the concomitant global inhibition of protein synthesis thus define a new mechanism of apoptosis initiation.
Asunto(s)
Neoplasias , ARN de Transferencia de Leucina , Línea Celular Tumoral , Muerte Celular , Apoptosis , Biosíntesis de ProteínasRESUMEN
DNMDP and related compounds, or velcrins, induce complex formation between the phosphodiesterase PDE3A and the SLFN12 protein, leading to a cytotoxic response in cancer cells that express elevated levels of both proteins. The mechanisms by which velcrins induce complex formation, and how the PDE3A-SLFN12 complex causes cancer cell death, are not fully understood. Here, we show that PDE3A and SLFN12 form a heterotetramer stabilized by binding of DNMDP. Interactions between the C-terminal alpha helix of SLFN12 and residues near the active site of PDE3A are required for complex formation, and are further stabilized by interactions between SLFN12 and DNMDP. Moreover, we demonstrate that SLFN12 is an RNase, that PDE3A binding increases SLFN12 RNase activity, and that SLFN12 RNase activity is required for DNMDP response. This new mechanistic understanding will facilitate development of velcrin compounds into new cancer therapies.
Asunto(s)
Fosfodiesterasas de Nucleótidos Cíclicos Tipo 3/química , Péptidos y Proteínas de Señalización Intracelular/química , Piridazinas/química , Adenosina Monofosfato/química , Rastreo Diferencial de Calorimetría , Dominio Catalítico , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/genética , Microscopía por Crioelectrón , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 3/genética , Endorribonucleasas/química , Células HEK293 , Células HeLa , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Cinética , Espectrometría de Masas , Complejos Multienzimáticos/ultraestructura , Mutación , Unión Proteica , Conformación Proteica en Hélice alfa , Multimerización de Proteína , Piridazinas/farmacología , Proteínas Recombinantes , Tetrahidroisoquinolinas/químicaRESUMEN
Florence Nightingale brought nursing from a disreputable and immoral vocation into the honest and ethical profession that is enjoyed today by emphasizing strict morals in the personal and work lives of her nursing students. In modern day, ethical principles guide the nursing profession and have many relevant connections to Nightingale's morals. Just as the high moral character of Nightingale's nurses helped nursing rise to a profession in her day, teaching and following ethical principles is crucial in furthering the nursing profession in our day.