P53 status influences regulation of HSPs and ribosomal proteins by PDTC and radiation John S. Thompson * , Reto Asmis, Judith Glass, Hua Liu, Colin Wilson, Brandy Nelson, Stephen A. Brown, Arnold J. Stromberg Veterans Affairs Medical Center, Lexington Kentucky, 40502, USA Department of Internal Medicine, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA Department of Statistics, University of Kentucky, Lexington, KY 40506, USA Department of Medicine, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA Received 17 February 2006 Available online 9 March 2006 Abstract Pyrrolidine dithiocarbamate (PDTC) is a thiol-containing compound that can act under varying conditions as an anti-oxidant or pro- oxidant. Utilizing microarrays, we determined the effect of PDTC +/À ionizing radiation (IR) on the expression of heat shock protein (HSP) genes in isolated B6/129 wild-type (WT) and p53À/À spleen cells. Extremely significant microarrays demonstrated that PDTC, but not IR, markedly up-regulated the expression of the majority of detectable HSP genes in WT and many to a significantly greater degree in p53À/À deficient cells. Determination of the glutathione/glutathione disulfide ratio indicated that PDTC was acting as a pro-oxidant under these conditions. From these data we conclude that the clinical use of ‘‘antioxidants’’ with radiotherapy or chemo- therapy must be very carefully based on knowledge of the p53 status of their intended normal and tumor target cells. Published by Elsevier Inc. Keywords: Microarray; Pyrrolidine dithiocarbamate; Ionizing radiation; Heat shock proteins; p53 The host response to stress may be the induction of many genes that regulate the induction of apoptosis and/ or necrosis. Included in this group are the genes encoding heat shock proteins (HSPs). Although under some circum- stances they have been associated with tissue injury [1], more commonly HSPs protect cells from a variety of inju- ries. A few examples include reduction in injury secondary to ischemia–reperfusion [2,3], experimental kidney trans- plantation [4],H 2 O 2 -induced apoptosis of L929 fibroblast cells [5], and radiation-induced cell apoptosis [6]. On the other hand, high levels of HSP70 [7] and HSP 90 [8] have been identified in tumor cells and reported to be in associ- ation with mutant p53. This suggests that they and perhaps other hsps could be possible targets for anti-cancer treatment. For example, agents targeting HSP 90 such as geldanamycin or a new investigational drug 17AAG could become clinically useful cancer therapeutic agents [8]. Unfortunately, high expression of HSPs may inhibit radia- tion [6] and chemotherapeutic drug [9] -induced apoptosis of cancer cells. Additionally, inclusion of anti-oxidants along with radiation or chemotherapeutic therapy must be carefully monitored. For example, Workman et al., have demonstrated that the anti-oxidant NAC prevents glen- danamycin-induced apoptosis of BCR-ABL cancer cells [8]. In addition to heat, HSPs can be induced by a large number of physical and pharmacological agents [10,11]. One such agent is pyrrolidine dithiocarbamate (PDTC). PDTC has been shown to induce heat shock factor 1 (HSF-1), a transcription factor mediating the expression of many HSPs including HSP 70 [12,13], HSP 90, HSP 10, and DNAJ protein homologs 1 [14]. 0006-291X/$ - see front matter Published by Elsevier Inc. doi:10.1016/j.bbrc.2006.02.159 * Corresponding author. Fax: +1 859 281 4989. E-mail address: jsthom1@uky.edu (J.S. Thompson). www.elsevier.com/locate/ybbrc Biochemical and Biophysical Research Communications 343 (2006) 435–442 BBRC