Differential gene expression in mouse mammary adenocarcinomas in the presence and absence of wild type p53.
The tumor suppressor p53 transcriptionally regulates a large number of target genes that may affect cell growth and cell death pathways. To better understand the role of p53 loss in tumorigenesis, we have developed a mouse mammary cancer model, the Wnt-1 TG/p53 model. Wnt-1 transgenic females that are p53-/- develop mammary adenocarcinomas that arise sooner, grow faster, appear more anaplastic, and have higher levels of chromosomal instability than their Wnt-1 transgenic p53+/+ counterparts. In this study, we used several assays to determine whether the presence or absence of p53 affects gene expression patterns in the mammary adenocarcinomas. Most of the differentially expressed genes are increased in p53+/+ tumors and many of these represent known target genes of p53 (p21WAF/C1P1, cyclin G1, alpha smooth muscle actin, and cytokeratin 19). Some of these genes (cytokeratin 19, alpha smooth muscle actin, and kappa casein) represent mammary gland differentiation markers which may contribute to the inhibited tumor progression and are consistent with the more differentiated histopathology observed in the p53+/+ tumors. Several differentially expressed genes are growth regulatory in function (p21, c-kit, and cyclin B1) and their altered expression levels correlate well with the differing growth properties of the p53+/+ and p53-/- tumors. Thus, while tumors can arise and progress in the presence of functioning wild type p53, p53 may directly or indirectly regulate expression of an array of genes that facilitate differentiation and inhibit proliferation, contributing to a more differentiated, slow growing, and genomically stable phenotype.
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Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA.
Donehower
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D000199:Actins / Q000235:genetics; D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D015153:Blotting, Western; D002364:Caseins / Q000235:genetics; D002455:Cell Division; D019926:Cyclin B / Q000235:genetics; D056744:Cyclin B1; D056746:Cyclin G; D056766:Cyclin G1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics; D005260:Female; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D007150:Immunohistochemistry; D015994:Incidence; D007633:Keratins / Q000235:genetics; D015674:Mammary Neoplasms, Animal / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D009363:Neoplasm Proteins / Q000235:genetics; D023282:Nuclease Protection Assays; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology; D012334:RNA, Neoplasm / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D051153:Wnt Proteins; D051155:Wnt1 Protein; D029961:Zebrafish Proteins
D000199:Actins; D002364:Caseins; C534700:Ccnb1 protein, mouse; C534703:Ccng1 protein, mouse; C493957:Cdkn1a protein, mouse; D019926:Cyclin B; D056744:Cyclin B1; D056746:Cyclin G; D056766:Cyclin G1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D012334:RNA, Neoplasm; D016159:Tumor Suppressor Protein p53; D051153:Wnt Proteins; D051155:Wnt1 Protein; C495246:Wnt1 protein, mouse; D029961:Zebrafish Proteins; D007633:Keratins