Challenging differential diagnosis of a wild-type gastrointestinal stromal tumour (GIST) or rare reticular perineurioma of the stomach? The role for mutational analysis.

The differential diagnosis of submucosal stomach lesions includes gastrointestinal stromal tumour (GIST), leiomyoma, synovial sarcomas, perineurioma, myxoid chondrosarcoma, myoepithelial tumour and other rare mesenchymal tumours. GISTs are well-defined lesions with distinctive morphologic and histogenetic characteristics that show 95% positive staining for CD117. Differential diagnosis of wild-type GISTs can be challenging. Here, we present two stomach tumours that were operated on in our surgical department. Both presented with positive immunoreactivity for CD117. In one tumour, c-Kit mutation analysis demonstrated positivity of exon 11_c.1674_1676delGGT, thus confirming the diagnosis of a GIST. Mutational analysis of the second stomach lesion demonstrated negativity for all known c-KIT and PDGFRA exons. In situ hybridisation ruled out a synovial sarcoma. An additional immunohistochemical staining for epithelial membrane antigen eventually confirmed the diagnosis of an extremely rare reticular perineurioma in the stomach, so far reported for the second time worldwide. Both patients have not shown any signs of recurrence 2 years after surgery. The presented cases emphasise the benefits of performing a mutational analysis in difficult GISTs, including wt-GISTs, and demonstrates the importance and challenges in differentiating GISTs from other mesenchymal tumours.

Down-regulation of MTUS1 in human colon tumors.

Loss of proliferative control and failure to undergo cellular differentiation are key events during carcinogenesis. We recently identified a new potential tumor suppressor gene named MTUS1 (mitochondrial tumor suppressor 1), down-regulated in undifferentiated tumor cell lines, inhibiting tumor cell proliferation after recombinant over-expression. The aim of this study was to investigate whether MTUS1 is also down-regulated in human tumor tissues, and whether reduced expression of MTUS1 enhances cellular proliferation. Expression of MTUS1 in human colon cancer tissues was compared with corresponding normal colon tissues using Western blot analysis and RT-PCR. Investigation of the DNA sequence and methylation pattern was performed using bisulfite reaction and DNA sequencing. Promotor activity was measured by promoter assays. Silencing of MTUS1 was carried out by siRNA transfection. Proliferation was measured by cell count. MTUS1 expression is significantly down-regulated in colon cancer tissues, compared to the corresponding normal tissues, on protein and mRNA level. No mutations of MTUS1 were detected in the coding sequence or the predicted promoter region in cancer tissues. No difference of CpG methylation, but an altered CpNpG methylation was found in the predicted promoter region. Functional significance of the predicted promoter region was demonstrated by promoter assays. Down-regulation of the MTUS1 expression by siRNA transfection significantly increased cellular proliferation. This study demonstrates a significant down-regulation of the MTUS1 expression in human colon cancer tissues. Since reduced expression of MTUS1 results in increased cellular proliferation, these data suggest that MTUS1 could be involved in the loss of proliferative control in human colon cancer.

Protein profiling of microdissected pancreas carcinoma and identification of HSP27 as a potential serum marker.

BACKGROUND: Patients with pancreatic adenocarcinomas have a poor prognosis because of late clinical manifestation and the tumor's aggressive nature. We used proteomic techniques to search for markers of pancreatic carcinoma. METHODS: We performed protein profiling of microdissected cryostat sections of 9 pancreatic adenocarcinomas and 10 healthy pancreatic tissue samples using ProteinChip technology (surface-enhanced laser desorption/ionization). We identified proteins by use of 2-dimensional gel electrophoresis, peptide fingerprint mapping, and immunodepletion and used immunohistochemistry for in situ localization of the proteins found. We used ELISA to quantify these proteins in preoperative serum samples from 35 patients with pancreatic cancer and 37 healthy individuals. RESULTS: From among the differentially expressed signals that were detected by ProteinChip technology, we identified 2 proteins, DJ-1 and heat shock protein 27 (HSP27). We then detected HSP27 in sera of patients by use of ELISA, indicating a sensitivity of 100% and a specificity of 84% for the recognition of pancreatic cancer. CONCLUSIONS: The detection of DJ-1 and HSP27 in pure defined tissue and the retrieval of HSP27 in serum by antibody-based methods identifies a potential marker for pancreatic cancer.

Orazipone, a locally acting immunomodulator, ameliorates intestinal radiation injury: a preclinical study in a novel rat model.

PURPOSE: Intestinal radiation injury (radiation enteropathy) is relevant to cancer treatment, as well as to radiation accidents and radiation terrorism scenarios. This study assessed the protective efficacy of orazipone, a locally-acting small molecule immunomodulator. METHODS AND MATERIALS: Male rats were orchiectomized, a 4-cm segment of small bowel was sutured to the inside of the scrotum, a proximal anteperistaltic ileostomy was created for intraluminal drug administration, and intestinal continuity was re-established by end-to-side anastomosis. After three weeks postoperative recovery, the intestine in the "scrotal hernia" was exposed locally to single-dose or fractionated X-radiation. Orazipone (30 mg/kg/day) or vehicle was administered daily through the ileostomy, either during and after irradiation, or only after irradiation. Structural, cellular, and molecular aspects of intestinal radiation toxicity were assessed two weeks after irradiation. RESULTS: Orazipone significantly ameliorated histologic injury and transforming growth factor-beta immunoreactivity levels, both after single-dose and fractionated irradiation. Intestinal wall thickness was significantly reduced after single-dose and nonsignificantly after fractionated irradiation. Mucosal surface area and numbers of mast cells were partially restored by orazipone after single-dose irradiation. CONCLUSIONS: This work (1) demonstrates the utility of the ileostomy rat model for intraluminal administration of response modifiers in single-dose and fractionated radiation studies; (2) shows that mucosal immunomodulation during and/or after irradiation ameliorates intestinal toxicity; and (3) highlights important differences between single-dose and fractionated radiation regimens.

Characterization of pepsinogen C as a potential biomarker for gastric cancer using a histo-proteomic approach.

We analyzed 74 cryostat sections of central gastric tumor, tumor margin, and normal gastric epithelium using ProteinChip Arrays and SELDI-TOF MS. One peak was significantly down-regulated in tumor tissue (P = 1.43 x 10(-6)) and identified as pepsinogen C using MS/MS analysis and immunodepletion. This signal was further characterized by immunohistochemistry. This work demonstrates that differentially expressed signals can be identified and assessed using a proteomic approach comprising tissue-microdissection, protein profiling, and immunohistochemistry.