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Background: O6-Methylguanine-DNA methyltransferase (MGMT) loss of expression has been suggested to be predictive of response to temozolomide in neuroendocrine tumours (NETs), but so far, only limited data are available. We evaluated the prognostic and predictive value of MGMT status, assessed by two molecular methods and immunohistochemistry, in a large series of NETs of different origins. Methods: A total of 107 patients, including 53 treated by alkylants (temozolomide, dacarbazine or streptozotocin), were retrospectively studied. In each case, we used methyl-specific PCR (MS-PCR) and pyrosequencing for evaluation of promoter methylation and immunohistochemistry for evaluation of protein status. Results: MGMT promoter methylation was detected in 12 out of 99 (12%) interpretable cases by MS-PCR and in 24 out of 99 (24%) by pyrosequencing. O6-Methylguanine-DNA methyltransferase loss of expression was observed in 29 out of 89 (33%) interpretable cases. Status of MGMT was not correlated with overall survival (OS) from diagnosis. Progression-free survival and OS from first alkylant use (temozolomide, dacarbazine and streptozotocin) were higher in patients with MGMT protein loss (respectively, 20.2 vs 7.6 months, P

The ΔNp63 protein, a product of the TP63 gene that lacks the N-terminal domain, has a critical role in the maintenance of self renewal and progenitor capacity in several types of epithelial tissues. ΔNp63 is frequently overexpressed in squamous cell carcinoma (SCC) and in some other epithelial tumours. This overexpression may contribute to tumour progression through dominant-negative effects on the transcriptionally active (TA) isoforms of the p53 family (TAp63, TAp73 and p53), as well as through independent mechanisms. However, the molecular basis of ΔNp63 overexpression is not fully understood. Here, we show that the expression of ΔNp63 is regulated by the Wnt/β-catenin pathway in human hepatocellular carcinoma (HCC) and SCC cell lines. This regulation operates in particular through TCF/LEF sites present in the P2 promoter of TP63. In addition, we show that ΔNp63 and β-catenin are frequently coexpressed and accumulated in oesophageal SCC, but not in HCC. These results suggest that activation of the β-catenin pathway may contribute to overexpression of ΔNp63 during tumour progression, in a cell type-specific manner.

Gastrointestinal stromal tumours (GISTs) are rare tumours of mesenchymal origin arising in the gastrointestinal tract. Incidence data obtained from registries indicate an incidence of approximately 12–15 new cases per million inhabitants per year in western countries (Goettsch et al, 2005; Nilsson et al, 2005); however, there remain uncertainties because of variations in diagnostic criteria before the NCI consensus reported in 2002 (Fletcher et al, 2002). Approximately 95% of GISTs stain positive for CD117 (KIT) and 85% of cases harbour activating mutations in the gene of one of two structurally related transmembrane tyrosine-kinase receptors: KIT and PDGFRA (Hirota et al, 1998; Heinrich et al, 2003a, 2003b; Corless et al, 2005). These activating mutations affect primarily the exons 9 and 11 of KIT, but may also be found on exons 8, 13 and 17 of KIT and exons 12, 14 and 18 of PDGFRA (Heinrich et al, 2003a, 2008; Debiec-Rychter et al, 2006). The relative frequency of the different KIT and PDGFRA mutations in patients with advanced GIST has been previously reported (Heinrich et al, 2003a, 2008; Debiec-Rychter et al, 2006). The frequency of KIT and PDGFRA mutations in localised GIST has been reported in a single-institution study from Italy. Other preliminary reports indicate that PDGFRA mutations may be higher in localised than metastatic GIST, which may reflect their more favourable prognosis. Two recent autopsy series have shown that the incidence of GIST may be as high as 50% in stomach specimens (Kawanowa et al, 2006; Agaimy et al, 2007); in one of these series, canonical KIT or PDGFRA mutations were found in 50% of assessable tumours (Agaimy et al, 2007). We sought to assess the precise incidence of GIST and other sarcomas in the Rhone-Alpes region in France. This report focuses exclusively on GIST.

Dysregulation of growth factors and their receptors is central to human hepatocellular carcinoma (HCC). We previously demonstrated that the Frizzled-7 membrane receptor mediating the Wnt signalling can activate the beta-catenin pathway and promotes malignancy in human hepatitis B virus-related HCCs. Expression patterns of all the 10 Frizzled receptors, and their extracellular soluble autoparacrine regulators (19 Wnt activators and 4 sFRP inhibitors) were assessed by real-time RT-PCR in 62 human HCC of different etiologies and their matched peritumorous areas. Immunostaining was performed to localise Frizzled on cell types in liver tissues. Regulation of three known Frizzled-dependent pathways (beta-catenin, protein kinase C, and C-Jun NH(2)-terminal kinase) was measured in tissues by western blot. We found that eight Frizzled-potentially activating events were pleiotropically dysregulated in 95% HCC and 68% peritumours as compared to normal livers (upregulations of Frizzled-3/6/7 and Wnt3/4/5a, or downregulation of sFRP1/5), accumulating gradually with severity of fibrosis in peritumours and loss of differentiation status in tumours. The hepatocytes supported the Wnt/Frizzled signalling since specifically overexpressing Frizzled receptors in liver tissues. Dysregulation of the eight Frizzled-potentially activating events was associated with differential activation of the three known Frizzled-dependent pathways. This study provides an extensive analysis of the Wnt/Frizzled receptor elements and reveals that the dysregulation may be one of the most common and earliest events described thus far during hepatocarcinogenesis.

Morphological sciences have recently experienced a significant technological breakthrough that offers new opportunities for cell and tissue imaging in situ but also raises new challenges to pathologists, who must adapt to a rapidly evolving environment. New partners, such as cell and molecular biologists, have provided pathologists with highly powerful tools for cell and subcellular imaging. They include: (a) the adaptation of techniques derived from molecular biology and cytogenetics, (b) the development of new microscopic tools, such as confocal microscopy, and (c) the emergence of new preparative techniques, such as microdissection or tissue arrays. However, recent technological progresses in various fields, from endoscopy to genomics, also raise new challenges to pathologists. Pathologists must therefore be prepared to redefine their area of expertise: this will be achieved through a continuous collaboration with all the partners involved in cell and tissue imaging and analysis but also by emphasising the importance of the informations provided by cell and tissue imaging in situ.

In Europe, high incidence rates of oesophageal squamous cell carcinoma (SCCE) are observed in western France (Normandy and Brittany) and in north-eastern Italy. Analysis of TP53 mutations in tumours from these regions has shown a high prevalence of mutations at A:T basepairs that may result from DNA damage caused by specific mutagens. However, the spectrum of TP53 mutations in regions of low incidence is unknown. We report here TP53 mutation analysis in 33 SCCE collected in Lyon, an area of low incidence. These tumours were also examined for MDM2 and P63 amplification, and for expression of p16INK4a/CDKN2a, cyclin E, p27Kipland Cox2. TP53 mutations were detected in 36% of the cases (12/33). In contrast with regions of high incidence, the mutation spectrum did not show a high prevalence of mutations at A:T base pairs. P63 was amplified in 5/32 cases tested (15.5%). No amplification of MDM2 was found. Expression studies revealed frequent loss of p16INK4a/CDKN2a(46%) and p27Kipl(25%) expression, and frequent overexpression of Cyclin E (70%) and Cox2 (42%). Overall, these results indicate that in Europe, SCCE from areas of high and low incidence present a similar pattern of molecular alterations but differ by the type of TP53 mutations. © 2001 Cancer Research Campaign http://www.bjcancer.com

International audience; Context: Deciphering the early processes occurring in adipose tissue during weight gain is a major issue for understanding the development of fat mass and obesity. Experimental overfeeding in humans is a unique situation to tackle these events. Objective: Our aim was to identify the pathways involved in sc adipose tissue remodeling during the initial phase of weight gain. Research Design and Methods: Forty-four healthy men were involved in an overfeeding protocol with a lipid-enriched diet (+ 760 kcal/d) for 2 months. Subcutaneous abdominal adipose tissue biopsies were taken for histology, transcriptomics, and Western blotting in the basal state, after 14 d, and at the end of the protocol. Results: Overfeeding significantly increased body weight (+ 2.5 kg) and fat mass. Reorganization of gene expression patterns occurred in adipose tissue with an up-regulation of numerous genes involved in lipid metabolism and storage, followed by clusters of genes related to angiogenesis and extracellular matrix remodeling. Histological examination showed increased microvascular density and connective tissue deposition after 56 d of overfeeding, with no changes in the number of macrophages or inflammatory cells. Inhibition of the canonical Wnt/beta-catenin signaling pathway and induction of the renin-angiotensin system might be implicated in the remodeling of sc adipose tissue. Conclusions: We characterize the coordinated and time-dependent processes that occur in human adipose tissue during the early phase of weight gain in healthy subjects and identify pathways representing potential targets in pathologies of adipose development, including obesity. (J Clin Endocrinol Metab 97: E183-E192, 2012)

Aims: To clarify the role of β-catenin in digestive endocrine carcinogenesis, a large and representative series of gastroenteropancreatic endocrine tumours was analysed in order to determine the incidence and pattern of β-catenin changes and to analyse the clinical and histological characteristics of the tumours presenting immunohistochemically detectable changes in β-catenin expression. Methods: 229 cases of gastroenteropancreatic endocrine tumours (stomach, 11; duodenum and ampulla, 29; jejunum and ileum, 51; appendix, 13; colon and rectum, 17; and pancreas, 108) were studied by immunohistochemistry to assess the pattern of distribution of β-catenin (membranous, cytoplasmic or nuclear). DNA was analysed to detect mutations in exon 3 of the CTNNB1 gene. Results: The distribution of immunoreactive β-catenin protein was membranous in 164 cases, cytoplasmic in 58 cases and nuclear in seven cases. No mutation was detected in exon 3 of the CTNNB1 gene in any case. The seven cases with nuclear accumulation of β-catenin were large tumours (mean size 44 (standard deviation (SD) 18.5) mm) with metastases, including liver metastases in five cases, high Ki-67 index (mean 34% (SD 16.5%)) and cyclin D1 overexpression; p53 accumulation was detected in six cases. Five patients died of disease; the mean (SD) survival was 13.6 (4.8) months. Conclusions: Immunohistochemically detectable nuclear accumulation of β-catenin is infrequent in gastroenteropancreatic endocrine tumours and is usually not associated with mutations in CNNTB1 exon 3. Changes in β-catenin expression are late events in digestive endocrine carcinogenesis, associated with tumour progression and dissemination.