p53 Gene and Protein Status: The Role of p53 Alterations in Predicting Outcome in Patients With Bladder Cancer Ben George, Ram H. Datar, Lin Wu, Jie Cai, Nancy Patten, Stephen J. Beil, Susan Groshen, John Stein, Donald Skinner, Peter A. Jones, and Richard J. Cote A B S T R A C T Purpose The p53 gene status (mutation) and protein alterations (nuclear accumulation detectable by immunohistochemistry; p53 protein status) are associated with bladder cancer progression. Substantial discordance is documented between the p53 protein and gene status, yet no studies have examined the relationship between the gene-protein status and clinical outcome. This study evaluated the clinical relationship of the p53 gene and protein statuses. Materials and Methods The complete coding region of the p53 gene was queried using DNA from paraffin-embedded tissues and employing a p53 gene–sequencing chip. We compared p53 gene status, mutation site, and protein status with time to recurrence. Results The p53 gene and protein statuses show significant concordance, yet 35% of cases showed discordance. Exon 5 mutations demonstrated a wild-type protein status in 18 of 22 samples. Both the p53 gene and protein statuses were significantly associated with stage and clinical outcome. Specific mutation sites were associated with clinical outcome; tumors with exon 5 mutations showed the same outcome as those with the wild-type gene. Combining the p53 gene and protein statuses stratifies patients into three distinct groups, based on recurrence-free intervals: patients showing the best outcome (wild-type gene and unaltered protein), an intermediate outcome (either a mutated gene or an altered protein) and the worst outcome (a mutated gene and an altered protein). Conclusion We show that evaluation of both the p53 gene and protein statuses provides information in assessing the clinical recurrence risk in bladder cancer and that the specific mutation site may be important in assessing recurrence risk. These findings may substantially impact the assessment of p53 alterations and the management of bladder cancer. J Clin Oncol 25:5352-5358. © 2007 by American Society of Clinical Oncology INTRODUCTION The p53 gene and protein statuses both play a critical role in the regulation of the normal cell cycle, cell cycle arrest, and apoptotic response. 1-3 Alterations in the p53 protein, leading to a loss of its tumor suppressor function, have been reported previously by us and by others. 4-6 The p53 gene status has been examined in a number of malignancies, including cancers of bladder, 7 breast, 8 lung, 9 ovary 10 and colo- rectal cancer. 11 The wild-type p53 protein has a short half-life of 15 to 30 minutes. 12 However, mis- sense p53 gene mutations result in a protein with a prolonged half-life, 13 which is the basis of its nuclear accumulation that is detectable by immunohisto- chemistry (IHC). Nuclear accumulation of the p53 protein in bladder cancer has been associated with mutations in the gene, although substantial discor- dance has been demonstrated between the altered p53 protein status (nuclear accumulation) and mu- tant p53 gene status. 14-17 Nuclear accumulation of p53 is associated with a poor clinical outcome in invasive bladder cancer. 4,5,18 However, there is evi- dence that the wild-type p53 protein can also accu- mulate to detectable levels, 19 in part because of aberrant expression of upstream regulators of p53 function. Further, the absence of nuclear accumula- tion of the p53 protein does not rule out a mutated p53 gene. 7,14,15 Few studies have examined the rela- tionship between the p53 gene status and clinical outcome because of the difficulty and cost of se- quencing. 7,20 The recent development of chip- based, p53 gene–sequencing technologies addresses this limitation. We had previously investigated p53 From the Departments of Pathology, Urology, Preventive Medicine, and Biochemistry, University of Southern California, Keck School of Medicine, Los Angeles; and Roche Molecular Systems, Pleasanton, CA. Submitted December 15, 2006; accepted July 19, 2007. Supported in part by Grants No. NCI CA 70903, NCI CA 14089, and NCI PO1 CA 86871 from the National Cancer Institute. B.G. and R.H.D. share first authorship. Authors’ disclosures of potential con- flicts of interest and author contribu- tions are found at the end of this article. Address reprint requests to Richard J. Cote, MD, FRCPath, Department of Pathology and Urology, University of Southern California Keck School of Medicine, 1441 Eastlake Avenue, NOR 2424, Los Angeles, CA 90033; e-mail cote_r@ccnt.usc.edu. © 2007 by American Society of Clinical Oncology 0732-183X/07/2534-5352/$20.00 DOI: 10.1200/JCO.2006.10.4125 JOURNAL OF CLINICAL ONCOLOGY O R I G I N A L R E P O R T VOLUME 25  NUMBER 34  DECEMBER 1 2007 5352 Downloaded from ascopubs.org by 3.239.82.167 on June 11, 2022 from 003.239.082.167 Copyright © 2022 American Society of Clinical Oncology. All rights reserved.