Apoptosis signal-regulating kinase 1 and cyclin D1 compose a positive feedback loop contributing to tumor growth in gastric cancer.

Mitogen-activated protein kinase (MAPK) pathways regulate multiple cellular functions and are highly active in many types of human cancers. Apoptosis signal-regulating kinase 1 (ASK1) is an upstream MAPK involved in apoptosis, inflammation, and carcinogenesis. This study investigated the role of ASK1 in the development of gastric cancer. In human gastric cancer specimens, we observed increased ASK1 expression, compared to nontumor epithelium. Using a chemically induced murine gastric tumorigenesis model, we observed increased tumor ASK1 expression, and ASK1 knockout mice had both fewer and smaller tumors than wild-type (WT) mice. ASK1 siRNA inhibited cell proliferation through the accumulation of cells in G1 phase of the cell cycle, and reduced cyclin D1 expression in gastric cancer cells, whereas these effects were uncommon in other cancer cells. ASK1 overexpression induced the transcription of cyclin D1, through AP-1 activation, and ASK1 levels were regulated by cyclin D1, via the Rb-E2F pathway. Exogenous ASK1 induced cyclin D1 expression, followed by elevated expression of endogenous ASK1. These results indicate an autoregulatory mechanism of ASK1 in the development of gastric cancer. Targeting this positive feedback loop, ASK1 may present a potential therapeutic target for the treatment of advanced gastric cancer.

Factors affecting the accuracy of endoscopic transpapillary sampling methods for bile duct cancer.

BACKGROUND AND AIM: Various methods for endoscopic transpapillary sampling have been developed. However, the factors affecting the accuracy of these methods for bile duct cancer are unknown. The aim of the present study was to determine the factors affecting the accuracy of endoscopic transpapillary sampling methods. METHODS: We reviewed the results from 101 patients with bile duct cancer who underwent transpapillary sampling by aspiration bile cytology, brushing cytology, and fluoroscopic forceps biopsy. The final diagnosis of bile duct cancer was made on the basis of pathological evaluation of specimens obtained at surgery and the clinical course over at least 1 year in patients not operated on. We carried out subgroup analyses for the factors affecting the accuracy of each transpapillary sampling method. RESULTS: Aspiration bile cytology was carried out 238 times in 77 patients, brushing cytology was carried out 67 times in 60patients, and fluoroscopic forceps biopsy was carried out 64 times in 53 patients. Accuracies of aspiration bile cytology were significantly higher for longer (≥15 mm) biliary cancerous lesions than for shorter (<15 mm) lesions (30% vs 18%, respectively, P = 0.049). Accuracies of brushing cytology and fluoroscopic forceps biopsy were significantly higher for non-flat than for flat-type biliary cancerous lesions (brushing: 58% vs 38%, respectively, P = 0.032; forceps biopsy: 60% vs 33%, respectively, P = 0.043). CONCLUSION: Endoscopic transpapillary sampling methods are more accurate for longer or elevated (non-flat) biliary cancerous lesions than for shorter or flat lesions.

Use of F-18 fluorodeoxyglucose positron emission tomography with dual-phase imaging to identify intraductal papillary mucinous neoplasm.

BACKGROUND & AIMS: We investigated the usefulness of dual-phase F-18 fluorodeoxyglucose positron emission tomography with computed tomography (FDG-PET/CT) to differentiate benign from malignant intraductal papillary mucinous neoplasms (IPMNs) and to evaluate branch-duct IPMNs. METHODS: We used FDG-PET/CT to evaluate IPMNs in 48 consecutive patients who underwent surgical resection from May 2004 to March 2012. IPMNs were classified as benign (n = 16) or malignant (n = 32) on the basis of histology analysis. The ability of FDG-PET/CT to identify branch-duct IPMNs was compared with that of the International Consensus Guidelines. RESULTS: The maximum standardized uptake value (SUVmax) was higher for early-phase malignant IPMNs than that for benign IPMNs (3.5 ± 2.2 vs 1.5 ± 0.4, P < .001). When the SUVmax cutoff value was set at 2.0, early-phase malignant IPMNs were identified with 88% sensitivity, specificity, and accuracy. The retention index values for malignant and benign IPMNs were 19.6 ± 17.8 and -2.6 ± 12.9, respectively. When the SUVmax cutoff was set to 2.0 and the retention index value to -10.0, early-phase malignant IPMNs were identified with 88% sensitivity, 94% specificity, and 90% accuracy. In identification of branch-duct IPMNs, when the SUVmax cutoff was set to 2.0, the sensitivity, specificity, and accuracy values were 79%, 92%, and 84%, respectively. By using a maximum main pancreatic duct diameter ≥7 mm, the Guidelines identified branch-duct IPMNs with greater specificity than FDG-PET/CT. The Guidelines criteria of maximum cyst size ≥30 mm and the presence of intramural nodules identified branch-duct IPMNs with almost equal sensitivity to FDG-PET/CT. CONCLUSIONS: Dual-phase FDG-PET/CT is useful for preoperative identification of malignant IPMN and for evaluating branch-duct IPMN.

Endoscopic sphincterotomy combined with large balloon dilation for removal of large bile duct stones.

BACKGROUND/AIMS: Recently, there have been sporadic reports of lithotomy using endoscopic sphincterotomy combined with large balloon dilation (EPLBD) against large or multiple bile duct stones. However, there are not many reports so far concerning this procedure. Therefore, we decided to discuss the results of EPLBD against large or multiple bile duct stones. METHODOLOGY: Stone retrieval using EPLBD was performed with 59 patients of choledocholithiasis, A) with 13 mm or more in shortest dimension, or B) multiple (≥3) bile duct stones, with the smallest more than 10 mm in shortest dimension. The papilla treated with endoscopic sphincterotomy (EST) was dilated using a 12-20 mm balloon suitable for the biliary ductal size. RESULTS: The success rate for the first lithotomy for choledocholithiasis was 83.1% (49/59). The final lithotomy rate was 100% (59/59). The time required for lithotomy was 43.7 (12-125) minutes and the number of treatment was 1.3 (1-4) on average. Lithotripsy was needed in 13.6% (8/59). The incidence of coincidental events associated with the procedure was 6.8% (4/59). No pancreatitis was noted. CONCLUSIONS: An endoscopic treatment using EST plus large balloon dilation against large or multiple bile duct stones was suggested to be safe and effective.

3-Deazaneplanocin A is a promising therapeutic agent for the eradication of tumor-initiating hepatocellular carcinoma cells.

Recent advances in stem cell biology have identified tumor-initiating cells (TICs) in a variety of cancers including hepatocellular carcinoma (HCC). Polycomb group gene products such as BMI1 and EZH2 have been characterized as general self-renewal regulators in a wide range of normal stem cells and TICs. We previously reported that Ezh2 tightly regulates the self-renewal and differentiation of murine hepatic stem/progenitor cells. However, the role of EZH2 in tumor-initiating HCC cells remains unclear. In this study, we conducted loss-of-function assay of EZH2 using short-hairpin RNA and pharmacological inhibition of EZH2 by an S-adenosylhomocysteine hydrolase inhibitor, 3-deazaneplanocin A (DZNep). Both EZH2-knockdown and DZNep treatment impaired cell growth and anchorage-independent sphere formation of HCC cells in culture. Flow cytometric analyses revealed that the two approaches decreased the number of epithelial cell adhesion molecule (EpCAM)(+) tumor-initiating cells. Administration of 5-fluorouracil (5-FU) or DZNep suppressed the tumors by implanted HCC cells in non-obese diabetic/severe combined immunodeficient mice. Of note, however, DZNep but not 5-FU predominantly reduced the number of EpCAM(+) cells and diminished the self-renewal capability of these cells as judged by sphere formation assays. Our findings reveal that tumor-initiating HCC cells are highly dependent on EZH2 for their tumorigenic activity. Although further analyses of TICs from primary HCC would be necessary, pharmacological interference with EZH2 might be a promising therapeutic approach to targeting tumor-initiating HCC cells.

Current situation of endoscopic treatment for common bile duct stones.

BACKGROUND/AIMS: The progression of endoscopy and devices as well as newly developed treatment methods have enabled endoscopic lithotomy. In this study, we examined to what degree is it possible to endoscopically treat patients who are diagnosed as having common bile duct stones. METHODOLOGY: Lithotomy was conducted using a backward side-viewing endoscope for patients without surgical history of upper gastrointestinal tract and patients with stomach reconstructed with Billroth-I method, using an ordinary endoscope for patients with stomach reconstructed with Billroth-II method (Bil-II) and using a double balloon endoscope for patients with difficulty in reaching the papilla or patients of Roux-en-Y anastomosis (R-Y). As for treatment methods, we selected endoscopic sphincterotomy as the first choice for papilla treatment and selected endoscopic papillary balloon dilation for patients with bleeding tendency or patients of Bil-II or R-Y. For patients with multiple stones or giant stones, lithotripsy was selected depending on judgment of the endoscopist. RESULTS: Endoscopic complete lithotomy was successful in 97.7% (168/172). An accidental disease was observed in 2.9% (5/172). In one patient with the perforated gastrointestinal tract, a surgery was performed but others were mild. CONCLUSIONS: Common bile duct stones can be endoscopically treated safely with high rate.

Identification of a suppressive mechanism for Hedgehog signaling through a novel interaction of Gli with 14-3-3.

Gli transcription factors are central effectors of Hedgehog signaling in development and tumorigenesis. Using a tandem affinity purification (TAP) strategy and mass spectrometry, we have found that Gli1 interacts with 14-3-3epsilon, and that Gli2 and Gli3 also bind to 14-3-3epsilon through homologous sites. This interaction depends on their phosphorylation, and cAMP-dependent protein kinase (PKA), a known negative regulator of Hedgehog signaling serves as a responsible kinase. A Gli2 mutant engineered to eliminate this interaction exhibited increased transcriptional activity (2 approximately 3x). Transcriptional repression by 14-3-3 binding was also observed with Gli3, when its N-terminal repressor domain was deleted. The phosphorylation sites responsible for the binding to 14-3-3 are distinct from those required for proteolysis, the known mechanism for PKA-induced repression of Hh signaling. Our data propose a novel mechanism in which PKA down-regulates Hedgehog signaling by promoting the interaction between Gli and 14-3-3 as well as proteolysis. Given the certain neuronal or malignant disorders in human caused by the abnormality of 17p13 encompassing 14-3-3epsilon overlap with increased Hh signaling, the Gli-14-3-3 interaction may have pathological significance for those human diseases.

Reduced expression of RAS protein activator like-1 in gastric cancer.

RAS signaling is frequently deregulated in human neoplasms. However, RAS mutations have been found in only a small proportion of human gastric cancers, implicating other mechanisms in the activation of RAS signaling in gastric tumorigenesis. We have previously reported that decreased expression of RAS protein activator like-1 (RASAL1), a member of the RAS-GTPase-activating proteins that switch off RAS activity, contributes to colon tumor progression. In our study, we explored the involvement of decreased RASAL1 expression in gastric tumorigenesis. RASAL1 expression was reduced in 6 of 10 gastric cancer cell lines examined by immunoblotting. Knockdown of RASAL1 increased mitogen-activated protein kinase signaling in response to growth factor stimulation, and the forced expression of RASAL1 reduced proliferation of gastric cancer cells. Immunohistochemical analyses in primary gastric tumors showed that RASAL1 expression was reduced in 23 of 48 (48%) of the gastric cancers but in none of the adenomas (0/10). Methylation of the RASAL1 promoter region and loss of heterozygosity (LOH) at the RASAL1 locus were examined to investigate the causes of RASAL1 silencing. All cell lines with reduced RASAL1 had RASAL1 methylation, and two had LOH. In primary gastric cancers, methylation or LOH was detected in 50% (6/12) of those with reduced RASAL1. Furthermore, RASAL1 expression was restored in some cell lines by histone deacetylase inhibitor treatment. Our findings demonstrate that reduced RASAL1 expression, partly due to genetic and epigenetic changes, contributes to gastric carcinogenesis, and also re-emphasize the importance of RAS signaling in gastric cancer development.

Altered composition of fatty acids exacerbates hepatotumorigenesis during activation of the phosphatidylinositol 3-kinase pathway.

BACKGROUND & AIMS: Some clinical findings have suggested that systemic metabolic disorders accelerate in vivo tumor progression. Deregulation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway is implicated in both metabolic dysfunction and carcinogenesis in humans; however, it remains unknown whether the altered metabolic status caused by abnormal activation of the pathway is linked to the protumorigenic effect. METHODS: We established hepatocyte-specific Pik3ca transgenic (Tg) mice harboring N1068fs*4 mutation. RESULTS: The Tg mice exhibited hepatic steatosis and tumor development. PPARγ-dependent lipogenesis was accelerated in the Tg liver, and the abnormal profile of accumulated fatty acid (FA) composition was observed in the tumors of Tg livers. In addition, the Akt/mTOR pathway was highly activated in the tumors, and in turn, the expression of tumor suppressor genes including Pten, Xpo4, and Dlc1 decreased. Interestingly, we found that the suppression of those genes and the enhanced in vitro colony formation were induced in the immortalized hepatocytes by the treatment with oleic acid (OA), which is one of the FAs that accumulated in tumors. CONCLUSIONS: Our data suggest that the unusual FA accumulation has a possible role in promoting in vivo hepato-tumorigenesis under constitutive activation of the PI3K pathway. The Pik3ca Tg mice might help to elucidate molecular mechanisms by which metabolic dysfunction contributes to in vivo tumor progression.

Utility of placement of pancreatic duct spontaneous dislodgement stent for prevention of post-ERCP pancreatitis in patients with difficulty in selective biliary cannulation.

BACKGROUND/AIMS: To examine the utility of placement of pancreatic duct spontaneous dislodgement stents for prevention of post-ERCP pancreatitis in patients with difficulty in selective biliary cannulation. METHODOLOGY: The incidence of pancreatitis was compared between the group with P(+) pancreatic duct spontaneous dislodgement stent placed for prevention of post-ERCP pancreatitis and the group without P(-) in patients with difficulty in selective biliary cannulation. RESULTS: The final success rate of selective biliary cannulation was 94.45%. Post-ERCP pancreatitis was observed at 7.07%. The success rate of placement of pancreatic duct stent in the P(+) group was 99.0%. The incidence of pancreatitis in 99 patients in the P(+) group was 3.0%, that of abdominal pain was 3.0%, that of hyperamylasemia was 16.2%, and the mean post-ERCP amylase level was 353.031 +/- 520.792 IU/L. The incidence of pancreatitis in the P(-) group was 11.1%, that of abdominal pain was 20.2%, that of hyperamylasemia was 33.3%, and the mean post-ERCP amylase level was 541.204 +/- 771.843 IU/L. Comparing between the P(+) group and P(-) group, the incidence of pancreatitis, that of abdominal pain, that of hyperamylasemia and the mean post-ERCP amylase level were significantly decreased in the P(+) group (p<0.05). CONCLUSION: Placement of pancreatic duct spontaneous dislodgement stent in patients with difficulty in selective biliary cannulation could be useful for prevention of post-ERCP pancreatitis.

Transpancreatic precut papillotomy in patients with difficulty in selective biliary cannulation.

BACKGROUND/AIMS: Transpancreatic precut papillotomy (TPPP) is considered as an effective method in patients with difficulty in selective biliary cannulation. However, the use of placing a pancreatic duct stent as a measure against post-ERCP pancreatitis has not been clarified. Here we examine the methods of implementing TPPP safely. METHODOLOGY: TPPP was conducted on patients with difficulty in selective biliary cannulation. The incidence of pancreatitis was compared between group P(+) in which a spontaneous dislodgement type pancreatic duct stent was placed and group P(-) without a duct stent. RESULTS: The success rate of biliary cannulation was 83.3% at the first ERCP and finally 93.9%. Post-ERCP pancreatitis was observed in 9.09% of patients. The success rate of placement of pancreatic duct stent in the P(+) group was 100%. The incidence of pancreatitis in the P(+) group was 4.1% and the mean post-ERCP amylase level was 340.071 ±420.035IU/L. The incidence of pancreatitis in the P(-) group was 23.5% and the mean post-ERCP amylase level was 661.250±772.285IU/L. The incidence of pancreatitis and the mean post-ERCP amylase level were significantly lower in the P(+) group (p<0.05). CONCLUSIONS: In the patients with difficulty in selective biliary cannulation, TPPP is a useful technique for biliary cannulation. The placement of a spontaneous dislodgement type pancreatic duct stent after TPPP may be useful for prevention of post-ERCP pancreatitis.

Pancreatic duct guidewire-indwelling method for patients resistant to selective biliary cannulation and usefulness of pre-cut papillotomy following unsuccessful biliary cannulation with pancreatic duct guidewire-indwelling method.

BACKGROUND/AIMS: Pancreatic duct guidewire-indwelling method (P-GW) is effective when selective biliary cannulation (SBC) has failed, but neither its true success rate nor a salvage technique have been established. In this study, we examined the usefulness of pre-cut papillotomy employing a pancreatic duct guidewire as the salvage treatment after unsuccessful SBC under P-GW. METHODOLOGY: P-GW was conducted in 55 patients. When cannulation under P-GW was unsuccessful, pre-cut papillotomy was performed. Then, if SBC after trial was still unsuccessful, ERCP was tried again at a later date. The incidence of pancreatitis following ERCP in patients with difficult SBC, with and without pancreatic duct stenting was determined. RESULTS: P-GW resulted in successful SBC in 63.6% of patients. For the 20 patients in which SBC failed pre-cut papillotomy using the pancreatic duct guidewire was performed. Transpancreatic pre-cut papillotomy was performed in 17 patients; 3 patients underwent needle-knife pre-cut papillotomy. SBC was successful at first attempt in 89.1% and eventually in 96.4% of patients. Post-ERCP pancreatitis occurred in 7.3%, broken down into 0% for those with pancreatic duct stenting (p=0.03) and 16.7% for those without. CONCLUSIONS: Pre-cut papillotomy using a pancreatic duct guidewire was useful for patients with unsuccessful SBC with P-GW alone, and the risk for pancreatitis was reduced by pancreatic stenting.

Macroscopic morphologic subtypes of laterally spreading colorectal tumors showing distinct molecular alterations.

Recent advances in colonoscopic techniques have resulted in more frequent detection of superficial-type colorectal tumors, that is, laterally spreading tumors (LSTs), although little is known about the characteristic clinical features and genetic alterations of LSTs. To elucidate the molecular characteristics of LSTs, genetic alterations in the KRAS, BRAF and PIK3CA genes and abnormal expression of the p53, beta-catenin and MYC proteins were analyzed using direct DNA sequencing and immunohistochemistry for 50 protruded-type tumors (Protruded), 35 granular-type LSTs (LST-G) and 19 nongranular-type LSTs (LST-NG). In addition, loss of heterozygosity (LOH) close to the adenomatous polyposis coli (APC) gene (5q21) was examined in these tumors. In univariate analyses, significant differences were noted in the percentages with KRAS mutations (Protruded, LST-G, LST-NG = 30.0%, 54.3%, 21.1%, respectively, p = 0.0156), nuclear accumulation of beta-catenin (Protruded, LST-G, LST-NG = 50.0%, 37.1%, 68.4%, respectively, p = 0.0267), expression of MYC (Protruded, LST-G, LST-NG = 26.0%, 17.1%, 42.1%, respectively, p = 0.0456) and LOH at the APC gene locus (Protruded, LST-G, LST-NG = 22.0%, 20.0%, 47.4%, respectively, p = 0.0302). Multivariate analysis demonstrated that the macroscopic subtype of LST was significantly associated with KRAS mutation (for LST-NG: odds ratio [OR] 0.23, 95% CI 0.06-0.90) and nuclear accumulation of beta-catenin (for LST-NG: OR 4.05, 95% CI 1.11-14.8). Our data revealed that the 2 subtypes of LST have different molecular characteristics, suggesting that 2 or more different molecular mechanisms result in colorectal tumors with a similar growth pattern.

Prognostic significance of genetic alterations detected by high-density single nucleotide polymorphism array in gastric cancer.

We sought to identify genomic changes that could be useful for clinical application, focusing on chromosomal instability and using a high-density single nucleotide polymorphism (SNP) array. We analyzed 34 gastric cancer cell lines for areas of DNA that exhibited copy number changes using the Affymetrix GeneChip Human Mapping 50 K Arrays. The results obtained with the cell lines were verified in 42 gastric cancer tissues using genomic PCR, quantitative real-time PCR, and loss of heterozygosity (LOH) analyses. Twenty-six local homozygous deletion regions, including 13 novel loci, and 31 recurrent high-grade gain regions, encompassing 14 novel loci, were found in the gastric cancer cell lines. Among the genes detected for high-grade gain in the cell lines, MYC, PAK1, and ITGB4BP showed copy number gain in more than 40% of gastric cancer tissues. LOH of AB051467, PTPRD, A2BP1, and C20orf133 was detected in more than 35% of gastric cancer tissues. The number of LOH was significantly greater in tumors with lymph node metastasis. In the early stage, the prognosis of patients with LOH of less than two genes was significantly better than that of those with LOH of two genes or more. Using high-density SNP arrays, we identified several novel and minute genomic alterations. LOH of four genes could be useful for prediction of lymph node metastasis and prognosis in early stage gastric cancers.

Decreased expression of the RAS-GTPase activating protein RASAL1 is associated with colorectal tumor progression.

BACKGROUND & AIMS: Although colorectal cancer (CRC) progression has been associated with alterations in KRAS and RAS signaling, not all CRC cells have KRAS gene mutations. RAS activity is modulated by RAS-GTPase-activating proteins (RASGAPs), so we investigated the role of RASGAPs in CRC progression. METHODS: The level of RASGAP expression in CRC cells was analyzed using quantitative real-time polymerase chain reaction. The expression of the RAS protein activator like-1 (RASAL1) was examined in clinical colorectal neoplasms using immunohistochemistry. The clinicopathologic (age, sex, and tumor site and grade) and molecular (KRAS gene mutation, as well as CTNNB1 and TP53 expression patterns) factors that could affect RASAL1 expression were examined. RESULTS: Of 12 RASGAPs examined, expression levels of only RASAL1 decreased in CRC cells; RASAL1 expression decreased in most CRC cells with wild-type KRAS gene but rarely in those with mutant KRAS gene. A transfection assay showed that RASAL1 repressed RAS/mitogen-activated protein kinase signaling in response to growth factor stimulation and reduced proliferation of CRC cells that contained wild-type KRAS gene. RASAL1 expression was detected in 46.9% (30/64) of adenocarcinoma, 17.4% (8/46) of large adenoma, and no (0/42) small adenoma samples. RASAL1 expression levels were correlated with the presence of wild-type KRAS gene in CRC tumor samples (P= .0010), distal location (P= .0066), and abnormal expression of TP53 (P= .0208). CONCLUSIONS: RASAL1 expression is reduced in CRC cells that contain wild-type KRAS gene. Reductions in RASAL1 expression were detected more frequently in advanced lesions than in small adenomas, suggesting that RASAL1 functions in the progression of benign colonic neoplasms.

Gastric cancer cell line Hs746T harbors a splice site mutation of c-Met causing juxtamembrane domain deletion.

Receptor tyrosine kinases (RTKs) are involved in oncogenesis and disease progression for many cancers. Inhibitors targeting them are vigorously developed and some of them are tested in the clinical setting. Amplifications of certain RTKs (c-Met, FGFR2 and ErbB2) have been associated with human gastric cancer progression. According to our genome-wide scans of genetic lesions in 34 gastric cancer cell lines using high-density single-nucleotide polymorphism genotyping microarrays, we confirmed that the c-met locus was amplified in four gastric cancer cell lines (Hs746T, MKN45, NUGC4 and SNU5). It was reported that somatic mutation is occasionally detected in tumor samples of a certain type of cancer with gene amplification. Previous reports showed gastric cancers harbored mutations of FGFR2 and ErbB2, but c-Met oncogenic mutation had not yet been reported. We performed mutational analysis of the cytoplasmic domains of c-Met using the genome DNA of the gastric cancer cell lines, and found that Hs746T cells had a splice site mutation of exon 14. By cDNA sequencing and Western blotting, we showed that the mutation caused juxtamembrane domain deletion. Previously, this mutation had been detected only in lung cancer specimens and this deletion resulted in the loss of Cbl E3-ligase binding causing decreased ubiquitination and delayed down-regulation. In conclusion, four gastric cancer cell lines harbored amplification of c-met locus, and among them, Hs746T had a putative oncogenic mutation with amplification. This information will be useful for screening of inhibitors targeting gastric cancer with c-Met aberration.

Regulation of the hedgehog signaling by the mitogen-activated protein kinase cascade in gastric cancer.

The hedgehog and mitogen-activated protein kinase (MAPK) signaling pathways regulate growth in many tumors, suggesting cooperation between these two pathways in the regulation of cell proliferation. However, interactions between these pathways have not been extensively studied. We assessed cross-talk between hedgehog and MAPK signaling in the regulation of cell proliferation in gastric cancer. We showed that PTCH expression was significantly correlated with extracellular signal-regulated kinase (ERK) 1/2 phosphorylation (P = 0.016) as well as SHH expression (P = 0.034) in the 35 gastric cancers assessed by immunohistochemistry. Indeed, MAPK signaling increased the GLI transcriptional activity and induced the expression of hedgehog target genes in gastric cancer cells. The inductive effect of activated KRAS and mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) 1 was blocked by the suppressor of fused (SUFU), indicating that MAPK signaling regulates GLI activity via a SUFU-independent process. Moreover, the deletion of the NH2-terminal domain of GLI1 gene resulted in reduced response to MEK1 stimulation. Our results suggest that the KRAS-MEK-ERK cascade has a positive regulatory role in GLI transcriptional activity in gastric cancer.

Down-regulation of hedgehog-interacting protein through genetic and epigenetic alterations in human hepatocellular carcinoma.

PURPOSE: Hedgehog (Hh) signaling is activated in several cancers. However, the mechanisms of Hh signaling activation in hepatocellular carcinoma (HCC) have not been fully elucidated. We analyzed the involvement of Hh-interacting protein (HHIP) gene, a negative regulator of Hh signaling, in HCC. EXPERIMENTAL DESIGN: Glioma-associated oncogene homologue (Gli) reporter assay, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, and quantitative real-time reverse transcription-PCR for the target genes of the Hh signals were performed in HHIP stably expressing hepatoma cells. Quantitative real-time PCR for HHIP was performed in hepatoma cells and 36 HCC tissues. The methylation status of hepatoma cells and HCC tissues was also analyzed by sodium bisulfite sequencing, demethylation assay, and quantitative real-time methylation-specific PCR. Loss of heterozygosity (LOH) analysis was also performed in HCC tissues. RESULTS: HHIP overexpression induced significant reductions of Gli reporter activity, cell viability, and transcription of the target genes of the Hh signals. HHIP was hypermethylated and transcriptionally down-regulated in a subset of hepatoma cells. Treatment with a demethylating agent led to the HHIP DNA demethylation and restoration of HHIP transcription. HHIP transcription was also down-regulated in the majority of HCC tissues, and more than half of HCC tissues exhibited HHIP hypermethylation. The HHIP transcription level in HHIP-methylated HCC tissues was significantly lower than in HHIP-unmethylated HCC tissues. More than 30% of HCC tissues showed LOH at the HHIP locus. CONCLUSIONS: The down-regulation of HHIP transcription is due to DNA hypermethylation and/or LOH, and Hh signal activation through the inactivation of HHIP may be implicated in the pathogenesis of human HCC.

Cholangiopancreatography troubleshooting: the usefulness of endoscopic retrieval of migrated biliary and pancreatic stents.

BACKGROUND: Stent migration in the hepatopancreatic duct might arise as one of the rare complications associated with biliary or pancreatic stenting. Although there are some procedures to retrieve the migrated stent, including surgical, percutaneous, and endoscopic approaches, endoscopy should be attempted first because it is least invasive. This study set out to evaluate the usefulness of endoscopic retrieval of migrated biliary and pancreatic stents. METHODS: Plastic stents that migrated in the bile duct (35 patients) or pancreatic duct (2) were retrieved with endoscopic retrograde cholangiopancreatography. Devices used were snare forceps, a basket catheter, grasping forceps, biopsy forceps, a balloon catheter, and the Soehendra stent retriever. RESULTS: Endoscopic retrieval of migrated stents was performed successfully in 36 (97.0%) of the 37 patients. The devices utilized for successful treatment were basket catheter (13 patients), grasping forceps (10), snare forceps (8), balloon catheter (3), biopsy forceps (1), and the Soehendra stent retriever (1). The unsuccessfully treated patient with chronic pancreatitis underwent surgery since the guide wire did not move forward due to bile duct stenosis, and there was also duodenal stenosis. One patient developed mild pancreatitis after withdrawal of the stent; the pancreatitis was relieved with conservative treatment. CONCLUSIONS: Endoscopic retrieval of migrated biliary and pancreatic stents appears to be useful because of its safety and low invasiveness. However, various forceps should be prepared for the retrieval of a migrated stent.

Integrated analysis of copy number alterations and loss of heterozygosity in human pancreatic cancer using a high-resolution, single nucleotide polymorphism array.

OBJECTIVE: To chart molecular genetic events in pancreatic cancer. METHODS: We analyzed genome-wide copy number alterations and loss of heterozygosity (LOH) in 25 established pancreatic cancer cell lines using a high-density single nucleotide polymorphism (SNP) array. We verified the data using genomic PCR and applied them to clinical samples. RESULTS: Twenty-six homozygous deletion regions were detected in at least 1 cell line and LOH was found at 9p, 18q, 17p, 8p, 13q, 6q, 3p, 6p, 22q, 9q and 12q with high frequency (>50%), consistent with a previous study. Moreover, we found 23 amplified regions in at least 2 cell lines, including 8 unreported loci. We then examined representative genes at the 8 amplified loci in matched pairs of pancreatic cancer and normal tissues. The amplification was detected in 1 (7.1%) to 5 (35.7%) of 14 microdissected tissue specimens. CONCLUSION: Using high-resolution SNP arrays, we studied genome-wide copy number alterations and LOH simultaneously. We identified several novel and minute genomic amplifications, which contained candidate oncogenes in human pancreatic cancers.