ABSTRACT
The major breast cancer suppressor proteins BRCA1 and BRCA2 play essential roles in homologous recombination (HR)-mediated DNA repair, which is thought to be critical for tumor suppression. The two BRCA proteins are linked by a third tumor suppressor, PALB2, in the HR pathway. While truncating mutations in these genes are generally pathogenic, interpretation of missense variants remains a challenge. To date, patient-derived missense variants that disrupt PALB2 binding have been identified in BRCA1 and BRCA2; however, there has not been sufficient evidence to prove their pathogenicity in humans, and no variants in PALB2 that disrupt either its BRCA1 or BRCA2 binding have been reported. Here we report on the identification of a novel PALB2 variant, c.104T>C (p.L35P), that segregates in a family with a strong history of breast cancer. Functional analyses showed that L35P abrogates the PALB2-BRCA1 interaction and completely disables its abilities to promote HR and confer resistance to platinum salts and PARP inhibitors. Whole-exome sequencing of a breast cancer from a c.104T>C carrier revealed a second, somatic, truncating mutation affecting PALB2, and the tumor displays hallmark genomic features of tumors with BRCA mutations and HR defects, cementing the pathogenicity of L35P. Parallel analyses of other germline variants in the PALB2 N-terminal BRCA1-binding domain identified multiple variants that affect HR function to varying degrees, suggesting their possible contribution to cancer development. Our findings establish L35P as the first pathogenic missense mutation in PALB2 and directly demonstrate the requirement of the PALB2-BRCA1 interaction for breast cancer suppression.
Subject(s)
BRCA1 Protein/metabolism , Breast Neoplasms/metabolism , Nuclear Proteins/metabolism , Tumor Suppressor Proteins/metabolism , Amino Acid Sequence , BRCA1 Protein/genetics , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Cell Line, Tumor , Fanconi Anemia Complementation Group N Protein , Female , Genetic Predisposition to Disease , Humans , Mutation, Missense , Nuclear Proteins/genetics , Protein Binding , Risk , Transfection , Tumor Suppressor Proteins/geneticsABSTRACT
The aim of this study was to assess the role of add-on devices for the prevention of phlebitis and other complications associated with the use of peripheral catheters. Patients admitted to an infectious diseases ward and requiring the insertion of a peripheral catheter for at least 24h were randomly allocated to be managed with or without add-on devices. Incidence of phlebitis and all complications were the primary outcomes. Extravasation, inadvertent withdrawal, obstruction and rupture were considered to be mechanical complications, and analysis was performed using survival methods. Of 683 evaluated catheters, 351 were allocated to the add-on device arm and 332 to the control arm. Despite randomisation, patients in the add-on device group were older (P=0.048), less likely to have human immunodeficiency virus (P=0.02) and more likely to have received antibiotics (P=0.05). After adjustment for these variables, the hazard ratio for phlebitis remained non-significant (hazard ratio: 0.95; 95% confidence interval: 0.7-1.3), but the risk of mechanical complications became lower in the add-on device arm (0.68; 0.5-0.94). This translated into a trend towards a lower risk of any complication (0.83; 0.67-1.01). The beneficial effect on mechanical or all complications was noticeable after six days of catheterisation. Add-on devices do not reduce the incidence of phlebitis but may prevent mechanical complications. However, the impact of add-on devices on the incidence of all complications is at most small and only apparent after the sixth day of catheter use.
