Project description:Expression profiling of thymic lymphomas derived from HIF1a+/+, p53R270H/R270H; HIF1a+/-, p53R270H/R270H; and HIF1aKI/+, p53R270H/R270H mice. HIF1a and HIF2a share a high degree of sequence homology, but recent work has shown that the two a subunits can have contrasting and tissue-specific effects on tumor growth. To directly compare the role of each HIFa subunit in spontaneous tumorigenesis, we bred a mouse model of expanded HIF2a expression and Hif1a+/- mice to homozygotes for the R270H mutation in p53. Heterozygosity for Hif1a significantly reduced the incidence of thymic lymphomas observed in this model. Moreover, reduced Hif1a levels correlated with decreased stabilization of activated Notch1 and expression of the Notch target genes, Dtx1 and Nrarp. Keywords: genetic modification, disease state analysis Thymic lymphoma tissue was preserved at the time mice were sacrificed. 4-5 samples from each of 3 genotypes (HIF1a+/-, p53R270H/R270H, HIF1aKI/+; p53R270H/R270H; and HIF1a+/+, p53R270H/R270H) were then used for microarray analysis to identify differences in gene expression that could account for changes in tumor onset and incidence.
Project description:Expression profiling of thymic lymphomas derived from HIF1a+/+, p53R270H/R270H; HIF1a+/-, p53R270H/R270H; and HIF1aKI/+, p53R270H/R270H mice. HIF1a and HIF2a share a high degree of sequence homology, but recent work has shown that the two a subunits can have contrasting and tissue-specific effects on tumor growth. To directly compare the role of each HIFa subunit in spontaneous tumorigenesis, we bred a mouse model of expanded HIF2a expression and Hif1a+/- mice to homozygotes for the R270H mutation in p53. Heterozygosity for Hif1a significantly reduced the incidence of thymic lymphomas observed in this model. Moreover, reduced Hif1a levels correlated with decreased stabilization of activated Notch1 and expression of the Notch target genes, Dtx1 and Nrarp. Keywords: genetic modification, disease state analysis
Project description:Our group previously demonstrated that the Trp53 R270H mutation can drive prostate cancer (CaP) initiation in a genetically engineered mouse model (FVB.129S4(Trp53tm3Tyj/wt);FVB.129S(Nkx3-1tm3(cre)Mmswt)). The objective of the current study was to identify molecules that may facilitate Trp53 R270H-mediated prostate carcinogenesis. Mice that harbor a Trp53 R270H germline mutation (B6.129S4-Trp53tm3.1Tyj/J) were used for the current study. Wildtype (Trp53WT/WT), heterozygous (Trp53R270H/WT), and homozygous mice (Trp53R270H/R270H) were exposed to 5 Gy radiation to activate and stabilize p53 and thereby enhance our ability to identify differences in transcriptional activity between the 3 groups of mice. Mouse prostates were harvested 6 hours post-irradiation and either processed for histological/immunohistochemistry (IHC) analysis or snap-frozen for RNA extraction and transcriptome profiling with RNA-Sequencing (RNA-Seq) analysis. IHC was used to assess cell proliferation (Ki67) and apoptosis (activated caspase 3). PIN lesions were observed in heterozygous and homozygous mice as early as 3 months, thereby validating our prior finding that the Trp53 R270H mutation can drive CaP initiation. RNA-Seq analysis identified 1,378 differentially expressed genes, including multiple wildtype p53 target genes (E.g. Cdkn1a, Bax, Bcl2, Kras, Mdm2), p53 gain-of-function (GOF) genes (Mgmt, Id4), and CaP-related genes (Cav-1, Raf1, Kras). Our combined data validate a role for the Trp53 R270H mutation in CaP initiation, and identify molecules that may contribute to Trp53 R270H-mediated prostate carcinogenesis.
Project description:We used gene transcript profiling to gain a deeper understanding of the role of FBXW7 in tumor development and to determine the influence of mTOR inhibition by rapamycin on tumor transcriptome and biological functions. In comparison to tumors from p53 single heterozygous (p53+/-) mice, we find that tumors from Fbxw7/p53 double heterozygous (Fbxw7+/-p53+/-) mice show significant deregulation of cholesterol metabolic processes independent of rapamycin treatment, while cell cycle related genes were upregulated in tumors from placebo treated Fbxw7+/-p53+/- mice, but not in tumors from rapamycin treated Fbxw7+/-p53+/- mice. On the other hand, tumors from rapamycin treated Fbxw7+/-p53+/- mice were enriched for genes involved in the integrated stress response, an adaptive mechanism to survive in stressful environments. p53+/â and p53+/âFbxw7+/â mice were generated by crossing p53-/- mice with Fbxw7+/- mice. At 5 weeks of age, mice were exposed whole-body to a single dose of 4 Gy X-ray irradiation. Mice were divided randomly into two groups and treated with rapamycin or placebo. RNA was isolated from thymic lymphomas.
Project description:The specific roles of mutant p53’s dominant-negative (DN) or gain-of-function (GOF) properties in regulating acute response and long-term tumorigenesis is unclear. Using “knock-in” mouse strains expressing varying R246S mutant levels, we show that DN effect on transactivation is universally observed after acute p53 activation whereas the effect on cellular outcome is cell-type specific. Reducing mutant p53 levels abrogated the DN effect. Mutant p53’s DN effect protected against radiation-induced death, but did not accentuate tumorigenesis. Furthermore, the R246S mutant did not promote tumorigenesis compared to p53-/- mice in various models, even in the absence of MDM2, unlike the R172H mutant. Together, these data demonstrate that mutant p53’s DN property only affects acute responses, whereas GOF is not universal, being mutation-type specific.
Project description:The specific roles of mutant p53’s dominant-negative (DN) or gain-of-function (GOF) properties in regulating acute response and long-term tumorigenesis is unclear. Using “knock-in” mouse strains expressing varying R246S mutant levels, we show that DN effect on transactivation is universally observed after acute p53 activation whereas the effect on cellular outcome is cell-type specific. Reducing mutant p53 levels abrogated the DN effect. Mutant p53’s DN effect protected against radiation-induced death, but did not accentuate tumorigenesis. Furthermore, the R246S mutant did not promote tumorigenesis compared to p53-/- mice in various models, even in the absence of MDM2, unlike the R172H mutant. Together, these data demonstrate that mutant p53’s DN property only affects acute responses, whereas GOF is not universal, being mutation-type specific.
Project description:The specific roles of mutant p53’s dominant-negative (DN) or gain-of-function (GOF) properties in regulating acute response and long-term tumorigenesis is unclear. Using “knock-in” mouse strains expressing varying R246S mutant levels, we show that DN effect on transactivation is universally observed after acute p53 activation whereas the effect on cellular outcome is cell-type specific. Reducing mutant p53 levels abrogated the DN effect. Mutant p53’s DN effect protected against radiation-induced death, but did not accentuate tumorigenesis. Furthermore, the R246S mutant did not promote tumorigenesis compared to p53-/- mice in various models, even in the absence of MDM2, unlike the R172H mutant. Together, these data demonstrate that mutant p53’s DN property only affects acute responses, whereas GOF is not universal, being mutation-type specific.
Project description:WAP-Cre:Ptenf/f:p53lox.stop.lox_R270H composite mice were generated by genetic crossing. In these mice, Pten is deleted and a R270H p53 mutation in the DNA binding domain is induced upon expression of Cre recombinase in pregnancy-identified alveolar progenitors. Tumors were characterized by histology, marker analysis, various bioinformatics methods, high-throughput (HTP) FDA-drug screen as well as orthotopic injection to quantify tumor initiating cells (TICs) and tail-vein injection to identify lung-metastasis. Expression data comparing 2 types of Pten-deficient tumors (spindle and poorly differentiated) with other modles of mouse mammary tumors 2 types of Pten deletion plus p53-R270H mutation tumors (spindle and poorly differentiated) was compared with MMTV-Neu, Spindle Pten-p53-deficient tumors, and wild-type mammary gland cells.
Project description:Lck-MyrAkt2 mice develop spontaneous thymic lymphomas at approximately 100-200 days of age, driven in part by a consitutatively-active AKT (due to myristoylation). mTOR Knock Down mice were crossed with Lck-MyrAkt postive mice to model the affects of decreasing mTOR activity on tumors with an activated PI3K/AKT/MTOR pathway. Lck-Akt/mTOR KD mice had prolonged survival compared to the Lck-Akt/mTOR WT mice. We used microarrays to compare the transcriptome in thymic lymphomas between Lck-Akt positive, mTOR WT and Lck-Akt positive, mTOR KD mice. Four thymic lymphomas from Lck-Akt/mTOR WT mice were compared to three thymic lymphomas from Lck-Akt/mTOR KD mice.