RESUMEN
Replication stress converts the stalled forks into reversed forks, which is an important protection mechanism to prevent fork degradation and collapse into poisonous DNA double-strand breaks (DSBs). Paradoxically, the mechanism also acts in cancer cells to contribute to chemoresistance against various DNA-damaging agents. PARP1 binds to and is activated by stalled forks to facilitate fork reversal. Aprataxin and polynucleotide kinase/phosphatase-like factor (APLF) binds to PARP1 through the poly(ADP-ribose) zinc finger (PBZ) domain and is known to be involved in non-homologous end joining (NHEJ). Here, we identify a novel function of APLF involved in interstrand DNA crosslink (ICL) repair and fork protection. We demonstrate that PARP1 activity facilitates the APLF recruitment to stalled forks, enabling the FANCD2 recruitment to stalled forks. The depletion of APLF sensitizes cells to cisplatin, impairs ICL repair, reduces the FANCD2 recruitment to stalled forks, and results in nascent DNA degradation by MRE11 nucleases. Additionally, cisplatin-resistant cancer cells show high levels of APLF and homologous recombination-related gene expression. The depletion of APLF sensitizes cells to cisplatin and results in fork instability. Our results reveal the novel function of APLF to facilitate ICL repair and fork protection, thereby contributing to cisplatin-resistant phenotypes of cancer cells.
Asunto(s)
Cisplatino , Reparación del ADN , Replicación del ADN , ADN-(Sitio Apurínico o Apirimidínico) Liasa , Resistencia a Antineoplásicos , Poli(ADP-Ribosa) Polimerasa-1 , Humanos , Antineoplásicos/farmacología , Línea Celular Tumoral , Cisplatino/farmacología , ADN/metabolismo , ADN/genética , Roturas del ADN de Doble Cadena , Daño del ADN , Replicación del ADN/efectos de los fármacos , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Resistencia a Antineoplásicos/genética , Proteína del Grupo de Complementación D2 de la Anemia de Fanconi/metabolismo , Proteína del Grupo de Complementación D2 de la Anemia de Fanconi/genética , Poli(ADP-Ribosa) Polimerasa-1/metabolismo , Poli(ADP-Ribosa) Polimerasa-1/genética , Proteínas de Unión a Poli-ADP-RibosaRESUMEN
Dynamic duplex sonography (DUS) is not comprehensive in the evaluation of arteriogenic erectile dysfunction (ED). We introduced a new parameter, the flow index (FI), into the assessment of arteriogenic ED. A retrospective review of a prospective database was conducted. Patients undergoing DUS and pelvic computed tomography angiography for the evaluation of ED were included. The FI was calculated from peak systolic velocity (PSV) and the percentages of pelvic arterial (PLA) stenosis. Correlations between PSV, PLA stenosis, the FI, and erectile function were calculated. Eighty-three patients were included. Compared with PSV, the FI had better correlations with the erection hardness score (EHS) (rs = 0.405, P < 0.001 for FI; rs = 0.294, P = 0.007 for PSV). For EHS < 3, the areas under the ROC curve of FI and PSV were 0.759 and 0.700, respectively. In patients with normal DUS but EHS < 3, PLA stenosis was more severe (62.5% vs. 10.0%, P = 0.015), and the FI was lower (8.35 vs. 57.78, P = 0.006), while PSV was not different. The FI is better than PSV in the evaluation of arteriogenic ED. On the other hand, assessment of the pelvic arterial system should be included in the evaluation of ED.
