PDF(Pubmed)
Abstract：
Germline TP53 pathogenic variants can lead to a cancer susceptibility syndrome known as Li-Fraumeni (LFS). Variants affecting its activity can drive tumorigenesis altering p53 pathways and their identification is crucial for assessing individual risk. This study explored the functional impact of TP53 missense variants on its transcription factor activity. We selected seven TP53 missense variants (c.129G > C, c.320A > G, c.417G > T, c.460G > A, c,522G > T, c.589G > A and c.997C > T) identified in Brazilian families at-risk for LFS. Variants were created through site-directed mutagenesis and transfected into SK-OV-3 cells to assess their transcription activation capabilities. Variants K139N and V197M displayed significantly reduced transactivation activity in a TP53-dependent luciferase reporter assay. Additionally, K139N negatively impacted CDKN1A and MDM2 expression and had a limited effect on GADD45A and PMAIP1 upon irradiation-induced DNA damage. Variant V197M demonstrated functional impact in all target genes evaluated and loss of Ser15 phosphorylation. K139N and V197M variants presented a reduction of p21 levels after irradiation. Our data show that K139N and V197M negatively impact p53 functions, supporting their classification as pathogenic variants. This underscores the significance of conducting functional studies on germline TP53 missense variants classified as variants of uncertain significance to ensure proper management of LFS-related cancer risks.
摘要：
种系TP53致病变体可导致称为Li-Fraumeni（LFS）的癌症易感性综合征。影响其活性的变体可以驱动肿瘤发生改变p53途径，它们的鉴定对于评估个体风险至关重要。本研究探讨了TP53错义变体对其转录因子活性的功能影响。我们选择了七个TP53错义变体(c.129G>C，c.320A>G，c.417G>T，c.460G>A，C,522G>T,c.589G>A和c.997C>T）在有LFS风险的巴西家庭中确定。通过定点诱变产生变体并转染到SK-OV-3细胞中以评估其转录激活能力。变体K139N和V197M在TP53依赖性荧光素酶报告基因测定中显示显著降低的反式激活活性。此外,K139N对CDKN1A和MDM2的表达产生负面影响，并且在辐射诱导的DNA损伤后对GADD45A和PMAIP1的影响有限。变体V197M在所评估的所有靶基因中表现出功能影响和Ser15磷酸化的丧失。K139N和V197M变体在照射后呈现p21水平的降低。我们的数据显示K139N和V197M对p53功能有负面影响，支持将其分类为致病变体。这强调了对种系TP53错义变异进行功能研究的重要性，这些变异被分类为不确定意义的变异，以确保对LFS相关癌症风险的适当管理。
