The P53 homolog p63 encodes multiple proteins with transactivating, apoptosis-inducing, and oncogenic activities. We showed that p63 is amplified and that DeltaNp63 isotypes are overexpressed in squamous cell carcinoma (SCC) and enhance oncogenic growth in vitro and in vivo. Moreover, p53 associated with DeltaNp63alpha and mediated its degradation. Here, we report that DeltaNp63 associates with the B56alpha regulatory subunit of protein phosphatase 2A (PP2A) and glycogen synthase kinase 3beta (GSK3beta), leading to a dramatic inhibition of PP2A-mediated GSK3beta reactivation. The inhibitory effect of DeltaNp63 on GSK3beta mediates a decrease in phosphorylation levels of beta-catenin, which induces intranuclear accumulation of beta-catenin and activates beta-catenin-dependent transcription. Our results suggest that DeltaNp63 isotypes act as positive regulators of the beta-catenin signaling pathway, providing a basis for their oncogenic properties.

p63 is a member of the p53 tumor suppressor gene family, which regulates downstream target gene expression by binding to sequence-specific response elements similar to those of p53. By using oligonucleotide expression microarray analysis and analyzing the promoters of p63-induced genes, we have identified novel p63-specific response elements (p63-REs) in the promoter regions of EVPL and SMARCD3. These p63-REs exhibit characteristic differences from the canonical p53-RE (RRRCWWGYYY) in both the core-binding element (CWWG) as well as the RRR and/or YYY stretches. Luciferase assays on mutagenized promoter constructs followed by electromobility shift analysis showed that p53 preferentially activates and binds to the RRRCATGYYY sequence, whereas p63 preferentially activates RRRCGTGYYY. Whereas EVPL protein is highly expressed in epithelial cells of the skin and pharynx in the p63 ؉/؉ mouse, it is undetectable in these tissues in the p63 ؊/؊ mouse. Our results indicate that p63 can regulate expression of specific target genes such as those involved in skin, limb, and craniofacial development by preferentially activating distinct p63-specific response elements.p63 is a member of the p53 tumor suppressor gene family. Similar to p53, p63 is a transcription factor that activates target genes through sequence-specific DNA binding (35,41,43,52,56). It has been shown that expression of p21 waf-1 , MDM2, and BAX are induced by TAp63s through binding to p53 response elements (p53-REs) (45). In spite of their structural similarities, p63 functions differ greatly from those of p53. The most striking difference is the apparent involvement of p63 in skin and limb development. The p63 knockout mouse exhibits skin and limb defects as well as craniofacial abnormalities (29, 57). On the other hand, the p53 knockout mouse develops normally but is prone to suffering from various cancers from an early age (7). Heterozygous p63 germ line mutations cause several skin and other developmental disorders (1,3,17,28,53). On the other hand, germ line mutations of p53 cause Li-Fraumeni syndrome, in which affected individuals are exceptionally prone to developing cancer (26). p63 complements p53-dependent apoptosis induced by DNA damage. However, p63 itself induces apoptosis to a lesser extent than p53 (12, 42).These differences may be due to the differential regulation of target genes by p53 and p63. The p53 and p63 proteins can bind to two or more tandem repeats of RRRCWWGYYY (p53-RE) or some other motifs and subsequently activate target gene expression (5, 9, 54, 56). In the case of the 14-3-3 promoter, p53 and p63 differentially bind to two distinct response elements (55). Until now, a number of genes have been reported to be targets of p63 and its close relative, p73, such as JAG1, JAG2, IL4R, ⌬Np73, AQP3, and REDD1 (11,30,39,40,59). However, p63-specific response elements (p63-REs) have not yet been defined. Thus, the specific mechanism of gene activation exhibited by p63 and its distinction from that exhibited by p53 remain unclear.In order...

Aberrant promoter hypermethylation of tumor suppressor genes is proposed to be a common feature of primary cancer cells. We recently developed a pharmacological unmasking microarray approach to screen unknown tumor suppressor gene candidates epigenetically silenced in human cancers. In this study, we applied this method to identify such genes in head and neck squamous cell carcinoma (HNSCC). We identified 12 novel methylated genes in HNSCC cell lines, including PGP9.5, cyclin A1, G0S2, bone-morphogenetic protein 2A, MT1G, and neuromedin U, which showed frequent promoter hypermethylation in primary HNSCC (60%, 45%, 35%, 25%, 25%, and 20%, respectively). Moreover, we discovered that cyclin A1 methylation was inversely related to p53 mutational status in primary tumors (P ‫؍‬ 0.015), and forced expression of cyclin A1 resulted in robust induction of wild-type p53 in HNSCC cell lines. Pharmacological unmasking followed by microarray analysis is a powerful tool to identify key methylated tumor suppressor genes and relevant pathways.

Hepatocellular carcinoma (HCC) is highly malignant and prone to multicentric occurrence. Differentiation between a true relapse of HCC and a second primary tumour appearing is of clinical importance. At this point, no convenient method is available to determine the origin of these HCCs. Tissue samples were obtained from 19 patients and analysed for the promoter hypermethylation status of multiple tumour suppressor genes (p16, DAP-Kinase, MGMT, GSTP1, APC, RIZ1, SFRP1, SFRP2, SFRP5, RUNX3, and SOCS1) using methylation-specific PCR (MSP). Methylation status was used to determine tumour clonality. In each of the 19 cases, at least one tumour was recognised as having an aberrantly methylated gene. The frequency of the methylation in tumour tissue was 57.1% in p16, 2.4% in DAP-kinase, 23.8% in GSTP1, 90.5% in APC, 45.2% in RIZ1, 64.3% in SFRP1, 59.5% in SFRP2, 28.6% in SFRP5, 47.6% in RUNX3, and 54.8% in SOCS1, while in MGMT, no aberrant methylation was detected. The methylation status of these genes was assessed using MSP as being either positive or negative, and was used to determine the tumour clonality. The clonality of every tumour could be decided even with lesions that could not be judged by clinical diagnosis or by another molecular method (mt DNA mutation). Determining the methylation status of multiple genes in multicentric HCC was useful as a clonal marker and provided useful information for characterising the tumour. From our findings, multicentric HCCs tend to occur more independently than metastatically from the original tumour. Expanded study should be pursued further for a better understanding of the molecular mechanism of hepatocarcinogenesis.

Pancreatectomy with PV resection can be performed safely. Even in radiographic classification type B, pathological PV wall invasion was observed in 51% of patients. Long-term survival was observed in types A and B, and grades 0 and 1.

We recently demonstrated the existence of speci®c patterns of somatic mitochondrial DNA (mtDNA) mutations in several cancers. Here we sought to identify the presence of mtDNA mutations in prostate cancer and their paired PIN lesions. The D-loop region, 16S rRNA, and the NADH subunits of complex I were sequenced to identify mtDNA mutations in 16 matched PIN lesions and primary prostate cancers. Twenty mtDNA mutations were detected in the tumor tissue of three patients. Identical mutations were also identi®ed in the PIN lesion from one patient. This patient with multiple point mutations also harbored a high frequency of microsatellite instability (MSI-H) in nuclear mononucleotide repeat markers. Remarkably, identical mutations were also detected in all (3/3) matched urine and plasma samples obtained from these patients. Although mitochondrial mutations are less common in prostate adenocarcinoma, they occur early in cancer progression and they can be detected in bodily¯uids of early stage disease patients. The identi®cation of MtDNA mutations may complement other early detection approaches for prostate cancer. Oncogene (2001) 20, 5195 ± 5198.

The most important indication for vascular resection in patients with pancreatic cancer is the ability to obtain cancer-free surgical margins. Otherwise, vascular resection is contraindicated. Extended lymphadenectomy may be not of benefit.

The m-BA method is safe and simple and improves postoperative outcomes. We suggest that the m-BA is suitable for use as a standard method of pancreaticojejunostomy after pancreatoduodenectomy.