A mutation within one allele of the p53 tumor suppressor gene can inactivate the remaining wild-type allele in a dominant-negative manner and in some cases can exert an additional oncogenic activity, known as mutant p53 gain of function (GOF). To study the role of p53 mutations in prostate cancer and to discriminate between the dominant-negative effect and the GOF activity of mutant p53, we measured, using microarrays, the expression profiles of three immortalized prostate epithelial cultures expressing wild-type, inactivated p53 or mutated p53. Analysis of these gene expression profiles showed that both inactivated p53 and p53 R175H mutant expression resulted in the upregulation of cell cycle progression genes. A second group, which was upregulated exclusively by mutant p53 R175H, was predominantly enriched in developmental genes. This group of genes included the Twist1, a regulator of metastasis and epithelial-mesenchymal transition (EMT). Twist1 levels were also elevated in metastatic prostate cancer-derived cell line DU145, in immortalized lung fibroblasts and in a subset of lung cancer samples, all in a mutant p53-dependent manner. p53 R175H mutant bearing immortalized epithelial cells showed typical features of EMT, such as higher expression of mesenchymal markers, lower expression of epithelial markers and enhanced invasive properties in vitro. The mechanism by which p53 R175H mutant induces Twist1 expression involves alleviation of the epigenetic repression. Our data suggest that Twist1 expression might be upregulated following p53 mutation in cancer cells.
Bibliographical noteFunding Information:
Acknowledgements. This research was supported by a Center of Excellence grant from Flight Attendant Medical Research Institute (FAMRI), EC FP6 Grant LSHC-CT-2004-503576, the Yad Abraham Center for Cancer Diagnosis and Therapy and the Ridgefield Foundation. Partial funding was provided by the Center for Women’s Health Research. This publication reflects the authors’ views and not necessarily those of the European Community. The EC is not liable for any use that may be made of the information contained herein. VR is the incumbent of the Norman and Helen Asher Professorial Chair Cancer Research at the Weizmann institute. ED is the incumbent of the Henry J Leir Professorial Chair. We are grateful to Alla Voldman and Leslie Pomeraniec for technical assistance.