Purpose: Cyclooxygenase-2 (COX-2) promotes carcinogenesis and its expression associates with clinicopathologic characteristics in gastric cancer. HuR is an mRNA binding protein that controls the stability of certain transcripts including COX-2.We evaluated the prognostic significance of COX-2 and HuR expressions in gastric cancer and whether there exists a link between HuR and COX-2 expressions. Experimental Design: The study included 342 consecutive patients with histologically confirmed gastric adenocarcinoma, of whom 321patients had tissue specimens available for COX-2 and 316 for HuR immunohistochemistry. Specimens were stained by COX-2^and HuR-specific monoclonal antibodies and scored by two independent observers. Correlation to clinical data and survival was assessed. TMK-1 gastric adenocarcinoma cells were treated with small interfering RNA against HuR and expressions of HuR and COX-2 were detected by immunofluorescence andWestern blot analysis. Results: Patients with low COX-2 expression had a cumulative 5-year survival of 53% and those with high COX-2 expression had 16% (P < 0.0001). In multivariate analysis, COX-2 was an independent prognostic factor (P = 0.003). Cytoplasmic HuR expression was associated with high COX-2 expression (P < 0.0001) and with reduced survival (P = 0.004) whereas nuclear positivity for HuR was not. When TMK-1 cells were treated with HuR small interfering RNA, expressions of HuR and COX-2 were reduced. Conclusions: High COX-2 is an independent prognostic factor in gastric cancer. Cytoplasmic expression of HuR associates with high COX-2 expression and with reduced survival, and tissue culture experiments show that HuR can regulate expression of COX-2 in gastric cancer cells.

BRAF V600E is the most common mutation in conventional ameloblastoma (AM) of the mandible. In contrast, maxillary AMs appear to harbor more frequently RAS, FGFR2, or SMO mutations. Unicystic ameloblastoma (UAM) is considered a less aggressive variant of ameloblastoma, amenable to more conservative treatment, and classified as a distinct entity. The aim of this study was to characterize the mutation profile of UAM ( n = 39) and to compare it to conventional AM ( n = 39). The associations between mutation status and recurrence probability were also analyzed. In the mandible, 94% of UAMs (29/31, including 8/8 luminal, 6/8 intraluminal, and 15/15 mural subtypes) and 74% of AMs (28/38) revealed BRAF V600E mutations. Among the BRAF wild-type cases, 1 UAM showed a missense SMO mutation (p.L412F), whereas 2 NRAS (p.Q61R), 2 HRAS (p.Q61R), and 2 FGFR2 (p.C383R) activating mutations were identified in AM. Of the 3 maxillary UAMs, only 1 revealed a BRAF V600E mutation. Taken together, our findings demonstrate high frequency of activating BRAF V600E mutations in both UAM and AM of the mandible. In maxillary UAMs, the BRAF V600E mutation prevalence appears to be lower as was shown for AM previously. It could therefore be argued that UAM and AM are part of the spectrum of the same disease. AMs without BRAF V600E mutations were associated with an increased rate of local recurrence ( P = 0.0003), which might indicate that routine mutation testing also has an impact on prognosis.

Pseudomyxoma peritonei (PMP) is a relatively rare clinical syndrome characterized by neoplastic epithelial cells growing in the peritoneal cavity and secreting mucinous ascites. Our aim was to explore the molecular events behind this fatal but under-investigated disease. We extracted DNA from 19 appendix-derived PMP tumors and nine corresponding normal tissues, and analyzed the mutational hotspot areas of 48 cancer-related genes by amplicon-based next-generation sequencing (NGS). Further, we analyzed the protein expression of V600E mutated BRAF, MLH1, MSH2, MSH6 and p53 from a larger set of PMP tumors (n 5 74) using immunohistochemistry. With NGS, we detected activating somatic KRAS mutations in all of the tumors studied. GNAS was mutated in 63% of the tumors with no marked difference between low-grade and high-grade tumors. Only one (5.3%) tumor showed oncogenic PIK3CA mutation, one showed oncogenic AKT1 mutation, three (15.8%) showed SMAD4 mutations and none showed an APC mutation. P53 protein was aberrantly expressed in higher proportion of high-grade tumors as compared with low-grade ones (31.3 vs. 7.1%, respectively; p 5 0.012) and aberrant expression was an independent factor for reduced overall survival (p 5 0.002). BRAF V600E mutation was only found in one (1.4%) high-grade tumor by immunohistochemistry (n 5 74). All the studied tumors expressed mismatch repair proteins MLH1, MSH2 and MSH6. Our results indicate that KRAS mutations are evident in all and GNAS mutations in most of the PMPs, but BRAF V600E, PIK3CA and APC mutations are rare. Aberrantly expressed p53 is associated with high-grade histology and reduced survival.Pseudomyxoma peritonei (PMP) is a relatively rare subtype of mucinous adenocarcinoma with estimated incidence of one to two persons per million per year. 1 PMP arises most often from mucinous neoplasms of the appendix, which leak tumor cells into the peritoneal cavity, colonize peritoneal cavity and produce abundant mucinous ascites. The classical low-grade (LG) form of PMP has been considered to be a rather benign disease, as it progresses slowly and does not by the definition show invasive characteristics. However, progressive obstruction makes even the LG form of PMP a fatal disease. In contrast, high-grade (HG) PMP possess invasive and metastasizing capacity with the 5-year survival being as low as 23%, while for the LG disease it is 63%. 2 At the moment, the optimal treatment for PMP is aggressive cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC). 3 In addition to PMP-related mortality, these complex treatments are, however, associated with considerable morbidity and mortality. 4 Furthermore, not all patients are amenable to these treatment options. 5 Thus, targeted therapies, even ones that would reduce mucin production, would be important additions to the treatment arsenal for PMP patients. To this end, biomarkers and prognostic factors would be helpful to estimate the aggressiveness of the disease and direct personalized treatment options...

The aim of the study was to detect mutations of BRAF oncogene in colorectal cancer and to use this information to identify Lynch syndrome patients. Consecutive cases of primary colorectal cancer (n = 137) were analyzed for MLH1 protein expression using immunohistochemistry (IHC). BRAF V600E mutation was detected by IHC using a specific monoclonal antibody (VE1) and by qPCR. All MLH1 protein-negative cases were subjected to microsatellite instability analysis and MLH1 promoter methylation assay. MLH1 protein expression deficiency and high microsatellite instability (MSI-H) were detected in 18 of the 137 (13.1%) consecutive colorectal cancer specimens. Detection of the BRAF V600E mutation by IHC was 100% sensitive and specific as compared to qPCR, and this mutation was frequently present in the MSI-H group (77.8%; 14/18) and less frequently in the microsatellite-stable group (7.6%; 9/118). All BRAF V600E mutated cases of the MSI-H group presented with a MLH1 promoter methylation (14/14) as detected by methylation-specific multiplex ligation-dependent probe amplification. When BRAF was wild type in the MSI-H group, only one MLH1 promoter methylation was detected (1/4), and of the remaining three cases without MLH1 methylation, two were identified to harbor an MLH1 mutation consistent with Lynch syndrome. Finally, 11 previously confirmed Lynch syndrome cases were analyzed for BRAF V600E mutation, and all of them were wild type. In conclusion, detection of BRAF V600E in colorectal cancer specimens by IHC is sensitive and specific and may help to identify Lynch syndrome patients.

Purpose: We have investigated the expression and regulation of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in gastric cancer. Experimental Design: Clinical gastric adenocarcinoma samples were analyzed by immunohistochemistry and quantitative real-time PCR for protein and mRNA expression of 15-PGDH and for methylation status of 15-PGDH promoter. The effects of interleukin-1h (IL-1h) and epigenetic mechanisms on 15-PGDH regulation were assessed in gastric cancer cell lines. Results: In a gastric cancer cell line with a very low 15-PGDH expression (TMK-1), the15-PGDH promoter was methylated and treatment with a demethylating agent 5-aza-2 ¶-deoxycytidine restored 15-PGDH expression. In a cell line with a relatively high basal level of 15-PGDH (MKN-28), IL-1h repressed expression of 15-PGDH mRNA and protein. This effect of IL-1h was at least in part attributed to inhibition of 15-PGDH promoter activity. SiRNA-mediated knockdown of 15-PGDH resulted in strong increase of prostaglandin E 2 production in MKN-28 cells and increased cell growth of these cells by 31% in anchorage-independent conditions. In clinical gastric adenocarcinoma specimens, 15-PGDH mRNA levels were 5-fold lower in gastric cancer samples when compared with paired nonneoplastic tissues (n = 26) and 15-PGDH protein was lost in 65% of gastric adenocarcinomas (n = 210). Conclusions: 15-PGDH is down-regulated in gastric cancer, which could potentially lead to accelerated tumor progression. Importantly, our data indicate that a proinflammatory cytokine linked to gastric carcinogenesis, IL-1h, suppresses 15-PGDH expression at least partially by inhibiting promoter activity of the 15-PGDH gene.

The worldwide incidence and mortality of gastric cancer (GC) remain high, and new concepts for diagnosis and treatment are needed. In this review, we summarize recent studies that applied next-generation sequencing approaches and also report the latest development in microRNA research. Two recently published studies identified somatic mutations in ARID1A gene in GC using exome sequencing. On the other hand, dysregulation of micro-RNA expression can alter processes such as proliferation, apoptosis, invasion, and metastasis. These novel markers may prove to be useful in earlier diagnosis and as prognostic or predictive markers in patients with GC .Gastric cancer (GC) is currently the fourth most common cancer worldwide, and 8% of the newly diagnosed cancer cases are malignancies of the stomach. Over 700,000 people die each year from GC, which makes it the second leading cause for cancer-related deaths [1]. GC is an asymptomatic disease at early stages and is therefore often detected late; the 5-year survival being only 20-30% [2]. As treatment modalities are limited, new approaches for diagnosis and treatment are necessary. This review focuses on recent discoveries by using next-generation sequencing and novel insights in the field of microRNA biology in GC.

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Cyclooxygenase-2 (COX-2) expression is a marker of poor prognosis in gastric cancer patients, and its inhibition suppresses gastric tumorigenesis in experimental animal models. The mechanism that leads to COX-2 overexpression in this tumor type is unknown. We have now shown that inhibition of phosphatidylinositol 3-kinase by LY294002 suppresses both basal and phorbol myristate acetate-induced COX-2 expression in TMK-1 and MKN-28 gastric cancer cells. Furthermore, inhibition of glycogen synthase kinase-3␤ (GSK-3␤) by SB415286 induced expression of COX-2 mRNA and protein as well as the enzyme activity in the gastric cancer cells. The effect of SB415286 was confirmed by the use of two additional GSK-3␤ inhibitors, lithium chloride and SB216763. SB415286 had a modest 1.6-fold stimulatory effect on a 2-kb COX-2 promoter reporter construct, but more importantly, it was shown to block the decay of COX-2 mRNA. In contrast to modulation of phosphatidylinositol 3-kinase/Akt/GSK-3␤ pathway, inhibitors of mitogen-activated protein kinases (MEK 1/2, p38, JNK) or the mammalian target of rapamycin did not alter COX-2 expression in gastric cancer cells. Our data show that inhibition of GSK-3␤ stimulates COX-2 expression in gastric cancer cells, which seems to be primarily facilitated via an increase in mRNA stability and to a lesser extent through enhanced transcription.