Gene expression profiling of favorable histology Wilms tumors and its correlation with clinical features.

The aims of this study were to understand the underlying molecular mechanisms of favorable histology Wilms tumors (WTs) and to classify them based on their molecular signatures. We studied a total of 15 favorable histology WTs using microarrays containing 19,968 cDNAs. First, we found commonly altered genes in WT. A total of 267 cDNAs were significantly overexpressed at least 3-fold in all of the tumors compared with noncancerous kidney and contained known WT-related genes such as IGF II and WT1. The gene with the highest expression change compared with noncancerous kidney was topoisomerase IIalpha. By hierarchical clustering, there was a clear distinction between high-stage and low-stage tumors. A total of 30 cDNAs were found differentially expressed between the high- and low-stage groups. One of them, Stathmin 1, which is involved in the microtubule system, was highly expressed in high-stage tumors compared with the low-stage tumors. The present chemotherapy regimens for WT consist mainly of topoisomerase II inhibitors (i.e., actinomycin D, doxorubicin, and etoposide) and antimicrotubule agents (i.e., vincristine and paclitaxel). Our data suggest that high expression of topoisomerase IIalpha and microtubule-related genes such as tubulin and stathmin 1 may be related to the high chemosensitivity of WT. In addition, retinol-related genes such as CRABP2 and retinol-binding protein 1 were overexpressed in WT, and CRABP2 was more highly expressed in the poor outcome patients, which suggests that retinoid acid may be a potential drug. In summary, our findings suggest that the integration of gene expression data and clinical parameters could aid in detecting aggressive tumors among favorable histology WT and lead to the discovery of new drugs for WT.

Differential expression of genes induced by resveratrol in LNCaP cells: P53-mediated molecular targets.

Prostate cancer prevention by key elements present in human nutrients derived from plants and fruits has been confirmed in various cell cultures and tumor models. Resveratrol (RE), a phytoalexin, induces remarkable inhibitory effects in prostate carcinogenesis via diverse cellular mechanisms associated with tumor initiation, promotion and progression. Earlier studies have shown that RE alters the expression of genes involved in cell cycle regulation and apoptosis, including cyclins, cdks, p53 and cdk inhibitors. However, most of the p53-controlled effects related to the role of RE in transcription either by activation or repression of a sizable number of primary and secondary target genes have not been investigated. Our study examined whether RE activates a cascade of p53-directed genes that are involved in apoptosis mechanism(s) or whether it modifies the androgen receptor and its co-activators directly or indirectly and induces cell growth inhibition. We demonstrate by DNA microarray, RT-PCR, Western blot and immunofluorescence analyses that treatment of androgen-sensitive prostate cancer cells (LNCaP) with 10(-5) M RE for 48 hr downregulates prostate-specific antigen (PSA), AR co-activator ARA 24 and NF-kB p65. Altered expression of these genes is associated with an activation of p53-responsive genes such as p53, PIG 7, p21(Waf1-Cip1), p300/CBP and Apaf-1. The effect of RE on p300/CBP plays a central role in its cancer preventive mechanisms in LNCaP cells. Our results implicate activation of more than one set of functionally related molecular targets. At this point we have identified some of the key molecular targets associated with AR and p53 target genes. These findings point to the need for further extensive studies on AR co-activators, such as p300, its central role in post-translational modifications such as acetylation of p53 and/or AR by RE in a time- and dose-dependent manner at different stages of prostate cancer that will fully elucidate the role of RE as a chemopreventive agent for prostate cancer in humans.

Functional and gene expression analysis of the p53 signaling pathway in clear cell sarcoma of the kidney and congenital mesoblastic nephroma.

Mutation of p53 has been implicated in progression of classical Wilms tumor (WT) into the anaplastic variant (AWT), drug resistance, and poor prognosis. Because of prognostic similarities, clear cell sarcoma of the kidney (CCSK) has been classified with AWT and other aggressive pediatric renal tumors, apart from congenital mesoblastic nephroma (CMN), which is instead a relatively benign tumor of neonates. Initially, CCSK and CMN were assumed to be ontologically related, but the role of p53 in the pathogenesis of either disease has not been sufficiently evaluated as in AWT. We examined the status of p53 in CMN and CCSK in comparison to AWT by immunohistochemistry and mRNA analysis of p53, the downstream effector p21(WAF-1/CIP-1) ( p21), the multidrug resistance gene MDR-1, a putative target of p53, and the p53-antagonist Mdm-2. Surprisingly, strong p53 nuclear immunoreactivity was found in cultures from two CMN specimens, but not in frozen or fixed tumor tissue from five other CMN specimens, nor in cell lines or tumor tissue from CCSK. Sequence analysis excluded p53 mutations. The size of the p53 mRNA in CMN and CCSK primary tumors excluded gross deletions or rearrangements. Low levels of Mdm-2 mRNA in CCSK and CMN primary tumors and cultures did not support a role for Mdm-2. Absence of MDR-1 mRNA excluded MDR-1 in the drug-resistant phenotype of CCSK. Cisplatin-induced p21 transactivation assays and G(1) cell cycle arrest analyses showed that p21 transactivation and G(1) arrest occurred in both CCSK and CMN cultures, demonstrating integrity of the p53 signal transduction pathway. Absence of p53 functional abnormalities excluded relationships between CCSK and CMN as in AWT, supporting the association of cellular CMN with congenital fibrosarcomas as more recently proposed.