Loss of TP53-DNA interaction induced by p.C135R in lung cancer

Abstract

The p53 tumor suppressor gene (TP53; OMIM: 191170) plays an important role in tumorigenesis in lung epithelial cells. TP53 encodes a sequence-specific DNAbinding protein that regulates transcription of several genes in response to DNA damage promoting cell cycle arrest, DNA repair or apoptosis. A mutation does not necessarily alter the protein function and since not all altered tumor protein p53 (TP53) conformations lead to the same biological properties, we studied Cys135Arg TP53 gene mutation in squamous cell type of non-small cell lung cancers (NSCLCs), by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and direct sequencing. Cys135Arg TP53 mutation, rare in databases (11/23544 in R11, IARC TP53 database), was detected. We chose p.C135R in order to examine DNA-TP53 interaction. A comparison with the wild-type after 1 nano-second molecular dynamic simulation analysis revealed a significant structural change (over 4Å displacement) in the contact loop Lys-Ser-Val which lies upstream and next to the mutated site in the TP53, that sterically prevents its DNA-binding activity. Additionally, the mutation produced a change in the electrostatic potential surface of the protein in the same loop where the structural modification took place. To demonstrate the degree of loss of function, functional assays in yeast and bacteria with oligonucleotides for competitive electrophoretic mobility shift assays (EMSAs) were done proving that this mutation decreases TP53 ability to bind DNA of the TP53 response element from the human p21 gene. These results demonstrate that the amino acid change C135R in the human TP53 generates the loss of TP53 DNA-binding activity directly affecting its role as a transcription factor and suggests that this observation can explain part of the phenotype described in patients affected by this type of tumor.

Tp53 haploinsufficiency is involved in hotspot mutations and cytoskeletal remodeling in gefitinib-induced drug-resistant EGFRL858R-lung cancer mice

“…Various residues located in different regions of p53 can be mutated during cancer progression and the therapeutic period. Many residues located in the DNA binding domain of p53 can be mutated to abolish its DNA binding activity, thereby causing p53 to lose its function as a transcriptional factor to regulate its target genes, which are involved in controlling cell cycle checkpoint-, DNA damage repair-and apoptosis-related genes [47,48]. In this study, we used deletion of Tp53 exon 5, whose encoded residues are located within the DNA binding domain, to abolish p53 DNA binding activity in mice to study its effect on mutation burden during the acquisition of TKI-induced drug resistance.…”

Comprehensive analysis of differential co-expression patterns reveal transcriptional dysregulation mechanism and identify novel prognostic lncRNAs in esophageal squamous cell carcinoma

“…The multifunctional TF TP53 was involved in the carcinogenesis of various malignancies, and is frequently mutated in >50% of human cancers 58–60. A lot of TP53 mutants can lead to the loss of its DNA-binding activity and affect its role as a TF 58–61…”

“…58 – 60 A lot of TP53 mutants can lead to the loss of its DNA-binding activity and affect its role as a TF. 58 – 61 …”