Gene Expression Profiling of p53+/‐ Knockout and Wild‐type Mice Following Diethylstilbestrol Administration

Abstract

SummaryStudies with clastogenic carcinogen diethylstilbestrol (DES) resulted in a broad of spectrum of toxic and carcinogenic effects in humans and rodents, but the cellular and molecular mechanism(s) by which it induces cancer is not clear. To identify putative genetic targets for p53 in vivo, we applied the cDNA macroarray gene expression profiles associated with apoptosis by comparing p53 +/7 knockout mice and wild-type mice on the kidney and uterus of female mice. p53 +/7 knockout mice and wild-type mice were treated with DES (500 mmole kg 71 ) or vehicle i.p once daily for 4 days. Total RNAs were obtained from kidney and uterus of both control and DES-treated. The signal intensities of individual gene spots on the membrane were quantified and normalized to the expression level of the GAPDH gene as an internal control. Our results demonstrated that 16 genes; bad, bax, bcl-2, bcl-w, bcl-x, caspase-3, caspase-7, caspase-8, c-myc, E124, GADD45, mdm2, NKkb1, p53, p21, Rb and trail were up-regulated and six genes; caspase-1, caspase-2, DR5, E2F1, FasL and iNOS did not changed in response to DES treatment in wild-type mice compared to p53 +/7 knockout mice. Most genes are involved in cell cycle regulation, signal transduction, apoptosis, or transcription. The greatest changes were seen in bad, bcl-x, mdm2, p53 and p21 gene expression in wild-type mice compared to p53 +/7 knockout mice. In comparing p53 and p21 gene expression in wild-type mice and p53 +/7 knockout mice, there was an 4.4-fold vs. 1.8-fold; 8-fold vs. 5.2-fold for kidney and16-fold vs. 5.5-fold; 2.1-fold vs. 8.3-fold for uterus samples increase in induction (respectively). RT-PCR and densitometric analysis was used to confirm the biggest changes of p21, p53 and bax genes. Using this approach, we have identified apoptosis associated genes regulated in response to DES and have revealed putative differences between the isogenic parent strain and p53 +/7 knockout mice, which will contribute to a better understanding of toxicity/carcinogenicity mechanisms in this model.

Does time management work? A meta-analysis

“…Media outlets routinely extol the virtues of time management. Employers, educators, parents, and politicians exhort employees, students, children, and citizens to embrace more efficient ways to use time [12][13][14][15][16]. In light of this, it is not surprising that from 1960 to 2008 the frequency of books mentioning time management shot up by more than 2,700% [17].…”

The use of genetically modified mice in cancer risk assessment: Challenges and limitations

“…The CYP450 levels in untreated Trp 53 +/− mice were also increased when compared to those of wild-type mice. Similarly, the expression of genes involved in cell cycle regulation, signal transduction, apoptosis, and transcription also appear to be significantly different between DES-treated p 53 heterozygous mice as compared to DES-treated wild-type mice (Salleh et al, 2004). Other genotoxic and other cellular responses (e.g.…”

Triggering apoptosis in tumors: an overview of potential approaches in treatment of leukemia

“…It engages BCL-2 (antiapoptotic B cell lymphoma 2) family of tens of genes, classified as pro-apoptotic or anti-apoptotic (pro-survival) genes. There are also many "independent" genes with critical role in regulation of cell-death such as TP53 (tumor protein 53) or other genes of cell-cycle regulation which is clearly shown in many genes knock-out studies (Chin & Fu, 1998;Salleh et al 2004). Critical components of apoptotic process are also caspases, a unique family of cysteine proteases.…”