Porcine model elucidates function of p53 isoform in carcinogenesis and reveals novel circTP53 RNA

Abstract

Recent years have seen an increasing number of genetically engineered pig models of human diseases including cancer. We previously generated pigs with a modified TP53 allele that carries a Cre-removable transcriptional stop signal in intron 1, and an oncogenic mutation TP53R167H (orthologous to human TP53R175H) in exon 5. Pigs with the unrecombined mutant allele (flTP53R167H) develop mainly osteosarcoma but also nephroblastomas and lymphomas. This observation suggested that TP53 gene dysfunction is itself the key initiator of bone tumorigenesis, but raises the question which aspects of the TP53 regulation lead to the development of such a narrow tumour spectrum. Molecular analysis of p53 revealed the presence of two internal TP53 promoters (Pint and P2) equivalent to those found in human. Consequently, both pig and human express TP53 isoforms. Data presented here strongly suggest that P2-driven expression of the mutant R167H-Δ152p53 isoform (equivalent to the human R175H-Δ160p53 isoform) and its circular counterpart circTP53 determine the tumour spectrum and play a critical role in the malignant transformation in flTP53R167H pigs. The detection of Δ152p53 isoform mRNA in serum is indicative of tumorigenesis. Furthermore, we showed a tissue-specific p53-dependent deregulation of the p63 and p73 isoforms in these tumours. This study highlights important species-specific differences in the transcriptional regulation of TP53. Considering the similarities of TP53 regulation between pig and human, these observations provide useful pointers for further investigation into isoform function including the novel circTP53 in both the pig model and human patients.

Allelic Expression Imbalance Analysis Identified YAP1 Amplification in p53- Dependent Osteosarcoma

“…A total of 39 flTP53 R167H/+ heterozygous and ten flTP53 R167H/R167H homozygous pigs were examined by necropsy. Out of 29 heterozygous animals, 18 developed bone tumours by the age of 36 months and 10 out of 10 homozygous pigs by the age of 16 months, all of which were classified histologically as osteoblastic osteosarcomas, as previously described [34].…”

“…We recently identified a mutant R167H-∆152p53 isoform in flTP53 R167H pigs, which is overexpressed in OS [34]. The cooperative role for the p53 pathway and YAP1 in mediating the tumorigenesis has been reported, reviewed in [61].…”

“…Pigs were humanely killed and examined by complete necropsy at the Tiergesundheitsdienst Bayern (Bavarian Animal Health Service). In total, 48 OS and matched healthy bone samples from hetero-and homozygous flTP53 R167H pigs were analysed, as previously described [34].…”

EGF-Induced miR-223 Modulates Goat Mammary Epithelial Cell Apoptosis and Inflammation via ISG15

“…It was demonstrated that the expression of ISG15 was also reduced by epidermal growth factor (EGF), which suggested the expression of ISG15 could be reduced by EGF-induced miR-223. The apoptotic rate was measured by flow cytometry and the expressions of anti-apoptotic Bcl-2 ( Bruckheimer et al, 1998 ), and pro-apoptotic caspase 3 ( Choudhary et al, 2015 ) and p53 ( Aubrey et al, 2018 ; Zhang et al, 2020a , 2021a ; Niu et al, 2021a , b ) were detected to evaluate the apoptosis of gMEC. The inflammation of gMEC was estimated by inflammation-related proteins.…”

The CRISPR/Cas9 Minipig—A Transgenic Minipig to Produce Specific Mutations in Designated Tissues

“…Single gene alteration has often not resulted in cancer, and transgenic pigs with overexpression of oncogenes have resulted in other complications that have compromised the model [ 13 , 14 ]. The few successful cancer models in pigs have revealed new aspects of cancer biology, for example highlighted by the insight to TP53, which is not evolutionary conserved to the mouse [ 15 ]. Hence, large animals can contribute to understanding cancer biology, leading to better cancer treatments.…”