A novel approach to cancer treatment using structural hybrids of the p53 gene family.

The p53 tumor suppressor belongs to a gene family that includes two other structurally and functionally related members: p73 and p63. The regulation of p53 activity differs significantly from that of p73 and p63. To enhance the tumor suppressive activity of p53, we constructed six recombinant adenoviruses that encode hybrid proteins with three functional domains derived from either p53 or TAp63γ. The potency of these hybrid molecules in suppressing tumorigenesis was evaluated using in vitro and in vivo models. Of the hybrid molecules tested, one hybrid named p63-53O was the most potent activator of apoptosis in human cancer cells. The p63-53O hybrid is composed of the transcriptional activation domain and DNA-binding domain of TAp63γ and the oligomerization domain of p53. The p63-53O hybrid efficiently transactivated p53AIP1. Moreover, silencing of p53AIP1 partially abolished the apoptotic response to p63-53O in human cancer cells. The p53-p63 hybrid molecule is a novel potent anti-proliferative agent for the treatment of cancer.

Silencing of Kruppel-like factor 2 by the histone methyltransferase EZH2 in human cancer.

The Kruppel-like factor (KLF) proteins are multitasked transcriptional regulators with an expanding tumor suppressor function. KLF2 is one of the prominent members of the family because of its diminished expression in malignancies and its growth-inhibitory, pro-apoptotic and anti-angiogenic roles. In this study, we show that epigenetic silencing of KLF2 occurs in cancer cells through direct transcriptional repression mediated by the Polycomb group protein Enhancer of Zeste Homolog 2 (EZH2). Binding of EZH2 to the 5'-end of KLF2 is also associated with a gain of trimethylated lysine 27 histone H3 and a depletion of phosphorylated serine 2 of RNA polymerase. Upon depletion of EZH2 by RNA interference, short hairpin RNA or use of the small molecule 3-Deazaneplanocin A, the expression of KLF2 was restored. The transfection of KLF2 in cells with EZH2-associated silencing showed a significant anti-tumoral effect, both in culture and in xenografted nude mice. In this last setting, KLF2 transfection was also associated with decreased dissemination and lower mortality rate. In EZH2-depleted cells, which characteristically have lower tumorigenicity, the induction of KLF2 depletion 'rescued' partially the oncogenic phenotype, suggesting that KLF2 repression has an important role in EZH2 oncogenesis. Most importantly, the translation of the described results to human primary samples demonstrated that patients with prostate or breast tumors with low levels of KLF2 and high expression of EZH2 had a shorter overall survival.

Risk of perforation during dilation for esophageal strictures after endoscopic resection in patients with early squamous cell carcinoma.

BACKGROUND AND STUDY AIMS: Growing evidence suggests that esophageal stricture frequently develops after endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) in early esophageal cancer patients, with an incidence proportional to the greater extent of mucosal defects resulting from improved EMR/ESD techniques. There seems to be a potential risk of perforation during bougienage in such patients. PATIENTS AND METHODS: 648 stricture dilations for 78 lesions in 76 patients were consecutively included. The outcomes after combined use of Maloney and Savary wire-guided bougienage for esophageal strictures after EMR/ESD were analyzed in a single-institute retrospective case series study. The perforation rate was determined and risk factors for perforation were identified. RESULTS: Patients underwent a median of 5.0 dilation procedures performed over a median 3.0 months for post-EMR/ESD strictures. Initial dilation was done a median 14 days following endoscopic resection. Perforations developed in seven patients (7/648 dilation procedures, 1.1%), all in the lower esophagus, and bleeding occurred in one patient (0.1% dilations). Two independent risk factors for development of perforation during dilation therapy for post-EMR/ESD stricture were identified: multiple dilations (odds ratio [OR] 1.2; P=0.012), and lower site of stricture (OR 12.8; P=0.043). Dysphagia was ameliorated by the dilations, and no patient required surgery. CONCLUSIONS: A specific emerging risk of perforation in dilation therapy for post-EMR/ESD strictures was identified. Carefully planned treatment is necessary in patients with severe post-EMR/ESD strictures especially strictures requiring multiple dilations or located in the lower esophagus.

Preventing oxidative stress: a new role for XBP1.

Antioxidant molecules reduce oxidative stress and protect cells from reactive oxygen species (ROS)-mediated cellular damage and probably the development of cancer. We have investigated the contribution of X-box-binding protein (XBP1), a major endoplasmic reticulum stress-linked transcriptional factor, to cellular resistance to oxidative stress. After exposure to hydrogen peroxide (H(2)O(2)) or a strong ROS inducer parthenolide, loss of mitochondrial membrane potential (MMP) and subsequent cell death occurred more extensively in XBP1-deficient cells than wild-type mouse embryonic fibroblast cells, whereas two other anticancer agents induced death similarly in both cells. In XBP1-deficient cells, H(2)O(2) exposure induced more extensive ROS generation and prolonged p38 phosphorylation, and expression of several antioxidant molecules including catalase was lower. Knockdown of XBP1 decreased catalase expression, enhanced ROS generation and MMP loss after H(2)O(2) exposure, but extrinsic catalase supply rescued them. Overexpression of XBP1 recovered catalase expression in XBP1-deficient cells and diminished ROS generation after H(2)O(2) exposure. Mutation analysis of the catalase promoter region suggests a pivotal role of CCAAT boxes, NF-Y-binding sites, for the XBP1-mediated enhancing effect. Taken together, these results indicate a protective role of XBP1 against oxidative stress, and its positive regulation of catalase expression may at least in part account for this function.

Proposal for a new clinical entity, IgG4-positive multiorgan lymphoproliferative syndrome: analysis of 64 cases of IgG4-related disorders.

BACKGROUND: Mikulicz's disease (MD) has been considered as one manifestation of Sjögren's syndrome (SS). Recently, it has also been considered as an IgG(4)-related disorder. OBJECTIVE: To determine the differences between IgG(4)-related disorders including MD and SS. METHODS: A study was undertaken to investigate patients with MD and IgG(4)-related disorders registered in Japan and to set up provisional criteria for the new clinical entity IgG(4)-positive multiorgan lymphoproliferative syndrome (IgG(4)+MOLPS). The preliminary diagnostic criteria include raised serum levels of IgG(4) (>135 mg/dl) and infiltration of IgG(4)(+) plasma cells in the tissue (IgG(4)+/IgG+ plasma cells >50%) with fibrosis or sclerosis. The clinical features, laboratory data and pathologies of 64 patients with IgG(4)+MOLPS and 31 patients with typical SS were compared. RESULTS: The incidence of xerostomia, xerophthalmia and arthralgia, rheumatoid factor and antinuclear, antiSS-A/Ro and antiSS-B/La antibodies was significantly lower in patients with IgG(4)+MOLPS than in those with typical SS. Allergic rhinitis and autoimmune pancreatitis were significantly more frequent and total IgG, IgG(2), IgG(4) and IgE levels were significantly increased in IgG(4)+MOLPS. Histological specimens from patients with IgG(4)+MOLPS revealed marked IgG(4)+ plasma cell infiltration. Many patients with IgG(4)+MOLPS had lymphocytic follicle formation, but lymphoepithelial lesions were rare. Few IgG(4)+ cells were seen in the tissue of patients with typical SS. Thirty-eight patients with IgG(4)+MOLPS treated with glucocorticoids showed marked clinical improvement. CONCLUSION: Despite similarities in the involved organs, there are considerable clinical and pathological differences between IgG(4)+MOLPS and SS. Based on the clinical features and good response to glucocorticoids, we propose a new clinical entity: IgG(4)+MOLPS.

Frequent epigenetic inactivation of Wnt antagonist genes in breast cancer.

Although mutation of APC or CTNNB1 (beta-catenin) is rare in breast cancer, activation of Wnt signalling is nonetheless thought to play an important role in breast tumorigenesis, and epigenetic silencing of Wnt antagonist genes, including the secreted frizzled-related protein (SFRP) and Dickkopf (DKK) families, has been observed in various tumours. In breast cancer, frequent methylation and silencing of SFRP1 was recently documented; however, altered expression of other Wnt antagonist genes is largely unknown. In the present study, we found frequent methylation of SFRP family genes in breast cancer cell lines (SFRP1, 7 out of 11, 64%; SFRP2, 11 out of 11, 100%; SFRP5, 10 out of 11, 91%) and primary breast tumours (SFRP1, 31 out of 78, 40%; SFRP2, 60 out of 78, 77%; SFRP5, 55 out of 78, 71%). We also observed methylation of DKK1, although less frequently, in cell lines (3 out of 11, 27%) and primary tumours (15 out of 78, 19%). Breast cancer cell lines express various Wnt ligands, and overexpression of SFRPs inhibited cancer cell growth. In addition, overexpression of a beta-catenin mutant and depletion of SFRP1 using small interfering RNA synergistically upregulated transcriptional activity of T-cell factor/lymphocyte enhancer factor. Our results confirm the frequent methylation and silencing of Wnt antagonist genes in breast cancer, and suggest that their loss of function contributes to activation of Wnt signalling in breast carcinogenesis.

Transcriptional silencing of hedgehog-interacting protein by CpG hypermethylation and chromatic structure in human gastrointestinal cancer.

Hedgehog-interacting protein (HHIP) was identified as a putative antagonist of the Hh pathway and as a target of Hh signalling. Our aim was to clarify the expression profiles and epigenetic alterations of the HHIP gene in gastrointestinal cancer. The expression and promoter epigenetic status of HHIP in cancer cell lines and freshly resected gastrointestinal cancer tissues were examined using RT-PCR, tissue microarray analysis, methylation-specific PCR, and chromatin immunoprecipitation assay. Cells were treated with the demethylating agent 5-aza-2'-deoxycytidine and/or histone deacetylase inhibitor trichostatin A. WST-8 assays and in vitro invasion assays after treatment with HHIP-specific siRNA were performed. HHIP expression levels were reduced in most of the gastrointestinal cancer cell lines and in a certain subset of cancer tissues, and these were correlated with promoter hypermethylation. A heterochromatic structure characterized by neither acetylated H3 nor acetylated H4, and histone H3 lysine 9 hypermethylation and histone H3 lysine 4 hypomethylation was observed in cancer cells in which the HHIP gene was aberrantly silenced. On the other hand, overexpression of the HHIP gene was also found in some cancer tissues and there were significant correlations between protein expression levels of HHIP and those of Sonic hedgehog (Shh), Indian hedgehog, Patched, and glioma-associated oncogene homologue-1. An association was found between lymph node metastasis and HHIP silencing in colorectal cancer tissues with strong Shh expression and between advanced TNM stage and HHIP silencing in diffuse-type gastric cancer tissues with strong Shh expression. Down-regulation of HHIP expression by siRNA resulted in a significant increase in colon cancer cell growth and invasion in vitro. Silencing of the HHIP gene due to hypermethylation and chromatin remodelling appears to be frequently involved in gastrointestinal tumourigenesis.

Frequent epigenetic inactivation of SFRP genes and constitutive activation of Wnt signaling in gastric cancer.

Activation of Wnt signaling has been implicated in gastric tumorigenesis, although mutations in APC (adenomatous polyposis coli), CTNNB1 (beta-catenin) and AXIN are seen much less frequently in gastric cancer (GC) than in colorectal cancer. In the present study, we investigated the relationship between activation of Wnt signaling and changes in the expression of secreted frizzled-related protein (SFRP) family genes in GC. We frequently observed nuclear beta-catenin accumulation (13/15; 87%) and detected the active form of beta-catenin in most (12/16; 75%) GC cell lines. CpG methylation-dependent silencing of SFRP1, SFRP2 and SFRP5 was frequently seen among GC cell lines (SFRP1, 16/16, 100%; SFRP2, 16/16, 100%; SFRP5, 13/16, 81%) and primary GC specimens (SFRP1, 42/46, 91%; SFRP2, 44/46, 96%; SFRP5, 30/46, 65%), and treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine rapidly restored SFRP expression. Ectopic expression of SFRPs downregulated T-cell factor/lymphocyte enhancer factor transcriptional activity, suppressed cell growth and induced apoptosis in GC cells. Analysis of global expression revealed that overexpression of SFRP2 repressed Wnt target genes and induced changes in the expression of numerous genes related to proliferation, growth and apoptosis in GC cells. It thus appears that aberrant SFRP methylation is one of the major mechanisms by which Wnt signaling is activated in GC.

Nonsteroidal anti-inflammatory drugs and oxidative stress in cancer cells.

Nonsteroidal antiinflammatory drugs (NSAIDs) induce apoptosis in a variety of cancer cells, including those of colon, prostate, breast and leukemia. In addition, the classical NSAIDs sulindac and aspirin are promising chemopreventive agents against colon cancer. NSAIDs inhibit cyclooxygenases (COX) preventing the formation of prostaglandins, prostacyclin and thromboxane. NSAIDs also exert other biological effects, including generation of reactive oxygen species (ROS) and inhibition of NF-kappaB-mediated signals. Despite many suggested mechanisms for their anticancer effects, it remains uncertain how they induce cell cycle arrest and apoptosis in cancer cells. Furthermore, there is little information on the selectivity of NSAIDs-mediated anticancer effects, although this is one of the most important issues in cancer therapy. Increased understanding of the biological basis for the anticancer activity of NSAIDs and their selectivity is essential for future therapeutic advances. In this paper, we propose that increased ROS generation is one of the key mechanisms for NSAIDs-mediated anticancer effects on various cancer cells.