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ABSTRACT:
PROVIDER: PRJNA814832 | ENA |
REPOSITORIES: ENA
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Project description:<h4>Background</h4>Colorectal cancer (CRC) development is a multi-step process resulting in the accumulation of genetic alterations. Despite its high incidence, there are currently no mouse models that accurately recapitulate this process and mimic sporadic CRC. We aimed to develop and characterize a genetically engineered mouse model (GEMM) of Apc/Kras/Trp53 mutant CRC, the most frequent genetic subtype of CRC.<h4>Methods</h4>Tumors were induced in mice with conditional mutations or knockouts in Apc, Kras, and Trp53 by a segmental adeno-cre viral infection, monitored via colonoscopy and characterized on multiple levels via immunohistochemistry and next-generation sequencing.<h4>Results</h4>The model accurately recapitulates human colorectal carcinogenesis clinically, histologically and genetically. The Trp53 R172H hotspot mutation leads to significantly increased metastatic capacity. The effects of Trp53 alterations, as well as the response to treatment of this model, are similar to human CRC. Exome sequencing revealed spontaneous protein-modifying alterations in multiple CRC-related genes and oncogenic pathways, resulting in a genetic landscape resembling human CRC.<h4>Conclusions</h4>This model realistically mimics human CRC in many aspects, allows new insights into the role of TP53 in CRC, enables highly predictive preclinical studies and demonstrates the value of GEMMs in current translational cancer research and drug development.
| S-EPMC7919037 | BioStudies
Project description:Small cell lung carcinoma (SCLC) is a highly lethal, smoking-associated cancer with few known targetable genetic alterations. Using genome sequencing, we characterized the somatic evolution of a genetically engineered mouse model (GEMM) of SCLC initiated by loss of Trp53 and Rb1. We identified alterations in DNA copy number and complex genomic rearrangements and demonstrated a low somatic point mutation frequency in the absence of tobacco mutagens. Alterations targeting the tumor suppressor Pten occurred in the majority of murine SCLC studied, and engineered Pten deletion accelerated murine SCLC and abrogated loss of Chr19 in Trp53; Rb1; Pten compound mutant tumors. Finally, we found evidence for polyclonal and sequential metastatic spread of murine SCLC by comparative sequencing of families of related primary tumors and metastases. We propose a temporal model of SCLC tumorigenesis with implications for human SCLC therapeutics and the nature of cancer-genome evolution in GEMMs.
| S-EPMC4040459 | BioStudies
Project description:We analyzed miRNA-based shRNA off-target effects by transducing Trp53-/- MEFs at single- and high-copy with six well-characterized, potent and weak Trp53 shRNAs. To advance RNAi therapy for KRAS-mutant cancer, we developed a functionally validated library of siRNAs against RAS pathway genes that minimize off-target effects and enable combination gene silencing at low dose. We developed an in vivo model for real-time tracking of nanoparticle-based siRNA delivery and offer proof-of-principle that siRNA-mediated inhibition of a single gene (KRAS) or combinations of genes (A/B/C-RAF or KRAS+PIK3C-A/B) can impair the growth of KRAS-mutant colorectal cancer xenografts. Trp53-/- MEFs were transduced with LMP expressing Trp53 shRNAs at single copy (11-21% infection efficiency) and high copy (>98% infection efficiency), selected on puromycin and grown in absence of the selection agent before harvest. Uninfected Trp53-/- MEFs and Trp53-/- MEFs infected with an empty vector control served as M-bM-^@M-^\no shRNAM-bM-^@M-^] reference.
| E-GEOD-59952 | BioStudies
Project description:Human colorectal carcinomas are defined by a nonrandom distribution of genomic imbalances that are characteristic for this disease. Often, these imbalances affect entire chromosomes. Understanding the role of these aneuploidies for carcinogenesis is of utmost importance. Currently, established transgenic mice do not recapitulate the pathognonomic genome aberration profile of human colorectal carcinomas. We have developed a novel model based on the spontaneous transformation of murine colon epithelial cells. During this process, cells progress through stages of pre-immortalization, immortalization and, finally, transformation, and result in tumors when injected into immunocompromised mice. We analyzed our model for genome and transcriptome alterations using ArrayCGH, spectral karyotyping (SKY), and array based gene expression profiling. ArrayCGH revealed a recurrent pattern of genomic imbalances. These results were confirmed by SKY. Comparing these imbalances with orthologous maps of human chromosomes revealed a remarkable overlap. We observed focal deletions of the tumor suppressor genes Trp53 and Cdkn2a/p16. High-level focal genomic amplification included the locus harboring the oncogene Mdm2, which was confirmed by FISH in the form of double minute chromosomes. Array-based global gene expression revealed distinct differences between the sequential steps of spontaneous transformation. Gene expression changes showed significant similarities with human colorectal carcinomas. Pathways most prominently affected included genes involved in chromosomal instability and in epithelial to mesenchymal transition. Our novel mouse model therefore recapitulates the most prominent genome and transcriptome alterations in human colorectal cancer, and might serve as a valuable tool for understanding the dynamic process of tumorigenesis, and for preclinical drug testing. © 2016 Wiley Periodicals, Inc.
| S-EPMC7832084 | BioStudies
Project description:Genotoxic colibactin-producing pks+ Escherichia coli induce DNA double-strand breaks, mutations, and promote tumor development in mouse models of colorectal cancer (CRC). Colibactin's distinct mutational signature is reflected in human CRC, suggesting a causal link. Here, we investigate its transformation potential using organoids from primary murine colon epithelial cells. Organoids recovered from short-term infection with pks+ E. coli show characteristics of CRC cells, e.g., enhanced proliferation, Wnt-independence, and impaired differentiation. Sequence analysis of Wnt-independent organoids reveals an enhanced mutational burden, including chromosomal aberrations typical of genomic instability. Although we do not find classic Wnt-signaling mutations, we identify several mutations in genes related to p53-signaling, including miR-34a. Knockout of Trp53 or miR-34 in organoids results in Wnt-independence, corroborating a functional interplay between the p53 and Wnt pathways. We propose larger chromosomal alterations and aneuploidy as the basis of transformation in these organoids, consistent with the early appearance of chromosomal instability in CRC.
| S-EPMC7881031 | BioStudies
Project description:Genetic alterations of tumor suppressor genes (TSGs) are frequently observed to have cumulative or cooperative tumorigenic effects. We examined whether the TSGs <i>Rb1</i>, <i>Trp53</i>, <i>Pten</i> and <i>Men1</i> have cooperative effects in suppressing neuroendocrine tumors (NETs) in mice. We generated pairwise homozygous deletions of these four genes in insulin II gene expressing cells using the Cre-LoxP system. By monitoring growth and examining the histopathology of the pituitary (Pit) and pancreas (Pan) in these mice, we demonstrated that pRB had the strongest cooperative function with PTEN in suppressing PitNETs and had strong cooperative function with Menin and TRP53, respectively, in suppressing PitNETs and PanNETs. TRP53 had weak cooperative function with PTEN in suppressing pituitary lesions. We also found that deletion of <i>Pten</i> singly led to prolactinomas in female mice, and deletion of <i>Rb1</i> alone led to islet hyperplasia in pancreas. Collectively, our data indicated that pRB and PTEN pathways play significant roles in suppressing PitNETs, while the Menin-mediated pathway plays a significant role in suppressing PanNETs. Understanding the molecular mechanisms of these genes and pathways on NETs will help us understand the molecular mechanisms of neuroendocrine tumorigenesis and develop effective preclinical murine models for NET therapeutics to improve clinical outcomes in humans.
| S-EPMC7367653 | BioStudies
Project description:We analyzed miRNA-based shRNA off-target effects by transducing Trp53-/- MEFs at single- and high-copy with six well-characterized, potent and weak Trp53 shRNAs. To advance RNAi therapy for KRAS-mutant cancer, we developed a functionally validated library of siRNAs against RAS pathway genes that minimize off-target effects and enable combination gene silencing at low dose. We developed an in vivo model for real-time tracking of nanoparticle-based siRNA delivery and offer proof-of-principle that siRNA-mediated inhibition of a single gene (KRAS) or combinations of genes (A/B/C-RAF or KRAS+PIK3C-A/B) can impair the growth of KRAS-mutant colorectal cancer xenografts. Trp53-/- MEFs were transduced with LMP expressing Trp53 shRNAs at single copy (11-21% infection efficiency) and high copy (>98% infection efficiency), selected on puromycin and grown in absence of the selection agent before harvest. Uninfected Trp53-/- MEFs and Trp53-/- MEFs infected with an empty vector control served as “no shRNA” reference.
2014-08-01 | E-GEOD-59952 | ArrayExpress
Project description:Mutations in the tumor protein p53 (TP53) are the most frequently occurring genetic events in high-grade ovarian cancers, especially the prevalence of the Trp53(R172H)-mutant allele. In this study, we investigated the impact of the Trp53(R172H)-mutant allele on epithelial ovarian cancer (EOC) in vivo We used the Pten/Kras(G12D)-mutant mouse strain that develops serous EOC with 100% penetrance to introduce the mutant Trp53(R172H) allele (homolog for human Trp53(R172H)). We demonstrate that the Trp53(R172H) mutation promoted EOC but had differential effects on disease features and progression depending on the presence or absence of the wild-type (WT) TP53 allele. Heterozygous WT/Trp53(R172H) alleles facilitated invasion into the ovarian stroma, accelerated intraperitoneal metastasis, and reduced TP53 transactivation activity but retained responsiveness to nutlin-3a, an activator of WT TP53. Moreover, high levels of estrogen receptor ? in these tumors enhanced the growth of both primary and metastatic tumors in response to estradiol. Ovarian tumors homozygous for Trp53(R172H) mutation were undifferentiated and highly metastatic, exhibited minimal TP53 transactivation activity, and expressed genes with potential regulatory functions in EOC development. Notably, heterozygous WT/Trp53(R172H) mice also presented mucinous cystadenocarcinomas at 12 weeks of age, recapitulating human mucinous ovarian tumors, which also exhibit heterozygous TP53 mutations (?50%-60%) and KRAS mutations. Therefore, we present the first mouse model of mucinous tumor formation from ovarian cells and supporting evidence that mutant TP53 is a key regulator of EOC progression, differentiation, and responsiveness to steroid hormones. Cancer Res; 76(8); 2206-18. ©2016 AACR.
| S-EPMC4873372 | BioStudies
Project description:Transplantable murine models of ovarian high grade serous carcinoma (HGSC) remain an important research tool. We previously showed that ID8, a widely-used syngeneic model of ovarian cancer, lacked any of the frequent mutations in HGSC, and used CRISPR/Cas9 gene editing to generate derivatives with deletions in Trp53 and Brca2. Here we have used one ID8 Trp53 -/- clone to generate further mutants, with additional mutations in Brca1, Pten and Nf1, all of which are frequently mutated or deleted in HGSC. We have also generated clones with triple deletions in Trp53, Brca2 and Pten. We show that ID8 Trp53 -/-;Brca1 -/- and Trp53 -/-;Brca2 -/- cells have defective homologous recombination and increased sensitivity to both platinum and PARP inhibitor chemotherapy compared to Trp53 -/-. By contrast, loss of Pten or Nf1 increases growth rate in vivo, and reduces survival following cisplatin chemotherapy in vivo. Finally, we have also targeted Trp53 in cells isolated from a previous transgenic murine fallopian tube carcinoma model, and confirmed that loss of p53 expression in this second model accelerates intraperitoneal growth. Together, these CRISPR-generated models represent a new and simple tool to investigate the biology of HGSC, and the ID8 cell lines are freely available to researchers.
| S-EPMC5715106 | BioStudies
Project description:MicroRNA-21 (miR-21) is overexpressed virtually in all human cancers and displays oncogenic activity in a transgenic murine model. Similarly, the p53 tumor suppressor gene is the most frequently mutated gene in human cancer, and its loss or mutation leads to tumor formation in mice. To ascertain the role of miR-21 in the p53 pathway in vivo and to characterize their interaction in tumorigenesis, we intercrossed the miR-21 (-/-) and Trp53 (-/-) mice. We found that Trp53 (-/-) miR-21 (-/-) mice develop tumors at a slightly later age, yet show a similar tumor spectrum and survival curve as Trp53 (-/-) mice. When subjected to genotoxic agents, tissues from Trp53 (-/-) miR-21 (-/-) mice have a higher percentage of apoptotic cells. We extracted mouse embryonic fibroblast cells (MEFs) to examine the impact of miR-21 loss on p53-regulated cellular processes in Trp53 (-/-) cells. Higher cellular apoptosis and senescence were found in Trp53 (-/-) miR-21 (-/-) MEFs than in Trp53 (-/-) MEFs. In addition, loss of miR-21 sensitizes transformed Trp53 (-/-) cells to DNA damage-induced apoptosis through elevation of Pten expression. These data suggest that inhibition of miR-21 would be beneficial in apoptosis-inducing cancer therapies directed against p53-deficient tumors.
| S-EPMC3670255 | BioStudies