Search

We aimed to evaluate the efficacy of texture and color enhancement imaging (TXI), which allows the acquisition of brighter images with enhanced color and surface structure in colorectal polyp detection compared to white light imaging.Patients who underwent colonoscopy with repeated ascending colon observation using TXI and white light imaging between August 2020 and January 2021 were identified in three institutions. The outcomes included the mean number of adenomas detected per procedure (MAP), adenoma detection rate (ADR), and ascending colonic adenoma miss rate (Ac-AMR). Logistic regression was used to determine the effects of the variables on the outcomes.We included 1043 lesions from 470 patients in the analysis. The MAP, ADR, flat polyp detection rate, and Ac-AMR in TXI and white light imaging were 1.5% (95% confidence interval 1.3-1.6%) vs. 1.0% (0.9-1.1%), 58.2% (51.7-64.6%) vs. 46.8% (40.2-53.4%), 66.2% (59.8-72.2%) vs. 49.8% (43.2-56.4%), and 17.9% (12.1-25.2%) vs. 28.2% (20.0-37.6%), respectively. TXI, age, withdrawal time, and endoscopy type were identified as significant factors affecting the MAP and the ADR using multivariate regression analysis.Our study indicates that TXI improve the detection of colorectal neoplastic lesions. However, prospective randomized trials are required to confirm these findings.

To examine whether reasonable detection rate of endoscopically diagnosed lesions as adenoma ("endoscopic" adenoma detection rate [ADR]) could be calculated with a database generated from colonoscopy reports and whether it could be used as a surrogate colonoscopy quality indicator of "pathological" ADR.A lesion-by-lesion database of colonoscopies performed between 2010 and 2020 at eight Japanese endoscopy centers and corresponding pathology database were integrated. Differences in numbers of detected polyps, "endoscopic" and "pathological" adenomas, and what these differences could be attributed to were examined. Polyp detection rate (PDR), "endoscopic" and "pathological" ADRs, and correlation coefficients between "pathological" ADR and PDR or "endoscopic" ADR by each endoscopist were calculated.Overall, 129,065 colonoscopy reports were analyzed. Among a total of 146,854 polyps, more "endoscopic" adenomas (117,359) were observed than "pathological" adenomas (70,076), primarily because adenomas were not resected on site, rather than because of a misdiagnosis. In all patients analyzed, PDR, "endoscopic" and "pathological" ADRs were 56.4% (95% confidence interval [CI]: 56.2-56.7), 48.0% (95% CI: 47.7-48.3), and 32.7% (95% CI: 32.5-33.0), respectively. "Endoscopic" and "pathological" ADRs from each endoscopist showed a high correlation in hospitals where adenomas were usually resected at the time of examination.By appropriately describing endoscopically diagnosed lesions as "adenomas" in endoscopy reports, "endoscopic" ADR might be used as a surrogate colonoscopy quality indicator of "pathological" ADR (UMIN000040690).

Background and aim Serrated lesions (SLs) have attracted attention as precursors of colorectal cancer (CRC). However, their prevalence, risk factors, and clinical significance have not been satisfactorily elucidated. This study used high-quality colonoscopy data to determine the prevalence of SLs and to identify their risk factors and relationship with synchronous advanced colorectal neoplasia (ACN) in asymptomatic screened individuals. Methods This study included data for 5218 individuals who underwent first-time screening colonoscopy by highly experienced endoscopists. The relationships between baseline characteristics and the presence of SLs and those between the presence of SLs and synchronous ACN were assessed using the chi-squared test and multivariate logistic regression. Results The proportions of individuals with SLs and right-sided SLs were 23.3% and 7.6%, respectively. Age, sex, family history of CRC, smoking, and body mass index were significantly related with the presence of SLs, and current smoking was most strongly associated with SLs (adjusted odds ratio [aOR] 2.6, 95% confidence interval [CI] 2.1-3.2). The aOR (95% CI) of the presence of SLs, SLs sized ≥ 10 mm, and right-sided SLs ≥ 5 mm for synchronous ACN was 1.4 (1.1-1.9), 3.5 (1.3-9.6), and 1.9 (1.0-3.8), respectively. The presence of left-sided SLs ≥ 10 mm (without right-sided SLs) was also significantly associated with ACN (aOR 8.1, 95% CI 2.0-33.7). Conclusions The relatively high prevalence of SLs and risk factors in screened individuals were elucidated and the significant relationship between SLs, particularly SLs ≥ 10 mm and right-sided SLs ≥ 5 mm, and synchronous ACN was confirmed.

We aimed to clarify the long-term outcomes of endoscopic resection (ER) for early gastric cancers (EGCs) based on pathological curability in a multicenter prospective cohort study.We analyzed the long-term outcomes of 9054 patients with 10,021 EGCs undergoing ER between July 2010 and June 2012. Primary endpoint was the 5-year overall survival (OS). The hazard ratio for all-cause mortality was calculated using the Cox proportional hazards model. We also compared the 5-year OS with the expected one calculated for the surgically resected patients with EGC. If the lower limit of the 95% confidence interval (CI) of the 5-year OS exceeded the expected 5-year OS minus a margin of 5% (threshold 5-year OS), ER was considered to be effective. Pathological curability was categorized into en bloc resection, negative margins, and negative lymphovascular invasion: differentiated-type, pT1a, ulcer negative, ≤2 cm (Category A1); differentiated-type, pT1a, ulcer negative,2 cm or ulcer positive, ≤3 cm (Category A2); undifferentiated-type, pT1a, ulcer negative, ≤2 cm (Category A3); differentiated-type, pT1b (SM1), ≤3 cm (Category B); or noncurative resections (Category C).Overall, the 5-year OS was 89.0% (95% CI, 88.3%-89.6%). In a multivariate analysis, no significant differences were observed when the hazard ratio of Categories A2, A3, and B were compared with that of A1. In all the pathological curability categories, the lower limit of the 95% CI for the 5-year OS exceeded the threshold 5-year OS.ER can be recommended as a standard treatment for patients with EGCs fulfilling Category A2, A3, and B, as well as A1 (UMIN Clinical Trial Registry, UMIN000005871).

Accurate diagnosis of invasion depth for T1 colorectal cancer is of critical importance as it decides optimal resection technique. Few reports have previously covered the effects of endoscopic morphology on depth assessment. We developed and validated a novel diagnostic algorithm that accurately predicts the depth of early colorectal cancer.We examined large pathological and endoscopic databases compiled between Jan 2015 and Dec 2018. Training and validation data cohorts were derived and real-world diagnostic performance of two conditional interference tree algorithms (Models 1 and 2) was evaluated against that of the Japan NBI-Expert Team (JNET) classification used by both expert and non-expert endoscopists.Model 1 had higher sensitivity in deep submucosal invasion than that of JNET alone in both training (45.1% vs. 28.6%, p 0.01) and validation sets (52.3% vs. 40.0%, p 0.01). Model 2 demonstrated higher sensitivity than Model 1 (66.2% vs. 52.3%, p 0.01) in excluding deeper invasion of suspected Tis/T1a lesions.We discovered that machine-learning classifiers, including JNET and macroscopic features, provide the best non-invasive screen to exclude deeper invasion for suspected Tis/T1 lesions. Adding this algorithm improves depth diagnosis of T1 colorectal lesions for both expert and non-expert endoscopists.

Superficially serrated adenoma (SuSA) is a recently proposed subtype of colorectal serrated lesion. We here report a sigmoid colon cancer derived from SuSA, which exhibited aggressive clinical behavior. Endoscopically, the tumor appeared as a superficial elevated lesion with a large nodule. Histological examination of the surgically resected material showed tubular adenocarcinoma associated with SuSA. Although tumor invasion was limited to the submucosal layer, lymph node and extranodal metastases were detected. The patient subsequently developed peritoneal metastases and died 15 months after surgery. Molecular analyses identified a KRAS mutation and a novel PRR15L-RSPO2 fusion, which retains the entire coding region of RSPO2, in both SuSA and adenocarcinoma components. The present study demonstrates the malignant potential of SuSA and expands the spectrum of RSPO fusions in colorectal neoplasms.

BACKGROUND AND AIM Superficially serrated adenoma (SuSA) is a recently proposed subtype of colorectal serrated lesions. It is characterized by distinct clinicopathological and molecular features, including mixed serrated and adenomatous histology and frequent genetic alterations involving KRAS and RSPO. This study aimed to characterize the endoscopic features of isolated and traditional serrated adenoma (TSA)-associated SuSAs. METHODS We retrospectively evaluated the endoscopic findings of 25 isolated SuSAs and 21 TSA-associated SuSAs that were histologically and molecularly characterized. RESULTS SuSAs appeared as a sessile polyp or slightly elevated lesion located mostly in the sigmoid colon and rectum (88%). The size was between 3 and 20 mm (median, 6 mm). Most of them exhibited KRAS mutations (96%) and RSPO fusions/overexpression (92%). Endoscopically, many lesions had a whitish color (84%), a distinct border (96%), an irregular border (76%), and a lobulated surface (72%). However, diminutive lesions exhibited overlapping features with hyperplastic polyps. On narrow-band imaging, vessel patterns were invisible or appeared as lacy microvessels in most lesions (80%). Chromoendoscopy invariably showed stellar or elongated/branched stellar pits, indicating a serrated microarchitecture. Most TSA-associated SuSAs typically presented as polyps with a two-tier raised appearance, consisting of whitish lower and reddish higher components corresponding to a SuSA and a TSA, respectively. CONCLUSIONS SuSAs exhibit several characteristic endoscopic features on white-light and image-enhanced endoscopy. Diminutive lesions exhibit endoscopic features overlapping with hyperplastic polyps. Nonetheless, the endoscopic diagnosis of larger and TSA-associated SuSAs may be feasible.

Cold snare polypectomy (CSP), a safe procedure for removing colon polyps, has a low prevalence of postpolypectomy bleeding (PPB). Previous studies have failed to demonstrate differences in PPB rates between CSP and hot snare polypectomy (HSP), possibly because of their small sample sizes. This study analyzed PPB rates after CSP and HSP.This was a retrospective analysis of colorectal lesions (diameter 10 mm) treated using endoscopic resection at our institution between January 2015 and December 2019. Resections were performed using CSP or HSP, depending on the endoscopist's preference. Endoscopic and histologic findings were recorded in the endoscopic database at our institution. Propensity score (PS) matching was performed to match patient age, lesion size, macroscopic features, location of the lesions, clipping after resection, and antithrombotic agent use. The CSP and HSP groups were compared to determine the adverse event (PPB) rates.The CSP and HSP groups included 12,928 and 2408 lesions (total of 5371 patients), respectively. Univariate analysis revealed that the overall prevalence of PPB after HSP was higher than that after CSP (odds ratio [OR], 5.39; 95% confidence interval [CI], 2.50-11.60). After PS matching (2135 lesions per group), the prevalence of PPB after HSP remained higher than that after CSP (OR, 6.0; 95% CI, 1.34-26.8).For colorectal lesions 10 mm in diameter, the risk of PPB after CSP is significantly lower than that after HSP, after PS matching. CSP for lesions 10 mm could be safely performed compared with HSP.

Pheochromocytomas and paragangliomas are neuroendocrine tumors which arise from adrenal medulla, and sympathetic or parasympathetic nerves, respectively. Hereditary cases afflicted by both or either pheochromocytomas and paragangliomas have been reported: these are called hereditary pheochromocytoma/paraganglioma syndromes (HPPS). Many cases of HPPS are caused by mutations of one of the succinate dehydrogenase (SDH) genes; mainly SDHB and SDHD that encode subunits for the mitochondrial respiratory chain complex II. In this study, we investigated mutations of SDH genes in six HPPS patients from four Japanese pedigrees using peripheral blood lymphocytes (from one patient with pheochromocytoma and five patients with neck paraganglioma) and tumor tissues (from two patients with paraganglioma). Results showed that all of these pedigrees harbor germline mutations in one of the SDH genes. In two pedigrees, a novel IVS2-2A>C mutation in SDHB, at the acceptor-site in intron 2, was found, and the tumor RNA of the patient clearly showed frameshift caused by exon skipping. Each of the remaining two pedigrees harbors a reported missense mutation, R242H in SDHB or G106D in SDHD. Importantly, all these mutations are heterozygous in constitutional DNAs, and two-hit mutations were evident in tumor DNAs. We thus conclude that the newly identified IVS2-2A>C mutation in SDHB is responsible for HPPS. The novel mutation revealed by our study may contribute to improvement of clinical management for patients with HPPS.

Although N-myc downstream regulated gene 2 (NDRG2) is frequently downregulated in various cancers and is considered to be a candidate tumor suppressor gene, molecular mechanisms of the expressional suppression that lead to cancers are largely unknown. Recent studies indicated that epigenetic suppression of NDRG2 involved carcinogenesis and progression in several tumor types, and we demonstrated positive association with NDRG2 suppression and poor prognosis in pancreatic cancer. In this study, we analyzed mRNA and protein expressions of NDRG2 in 26 cancer cell lines (20 colorectal and 6 gastric cancers) and found that many cell lines showed variously reduced NDRG2 expressions. Furthermore, NDRG2 expressions were significantly reduced in primary resected cancer tissues compared to corresponding normal tissues immunohistochemically (19 of 20 colorectal and 14 of 17 gastric cancers). Treatment with 5-Aza-2' deoxycytidine predominantly upregulated NDRG2 expressions in NDRG2 low-expressing cell lines. Bisulfite sequencing analyses and methylation specific PCR revealed that methylation status at one of the two promoters (around exon 2) correlated well with the suppressed expression, and this is the major promoter in colorectal and gastric cancer cell lines. Our present results suggest that hypermethylation in promoter around exon 2 is functioning as essential factors of NDRG2 silencing in gastrointestinal cancers.

DNA methyltransferase (DNMT) inhibitors are epigenetic drugs used to treat myelodysplastic syndrome. They not only induce DNA demethylation but also have significant cytostatic and cytotoxic effects; however, the relationships between these characteristics have not been established yet due to the lack of a method to induce only DNA demethylation. Herein, we show that a fusion protein comprised of the methyl‐CpG‐binding domain (MBD) and the catalytic domain of Ten‐eleven translocation protein 1 (TET1‐CD) globally demethylates and upregulates a number of methylated genes. These upregulated genes frequently contained CpG islands (CGIs) within ± 1000 bp of the transcription start site (TSS). Interestingly, 65% of the genes upregulated fivefold or more by MBD‐TET1‐CDwt were also reactivated after treatment with a DNMT inhibitor, 5‐azacytidine (Aza‐CR), suggesting that gene reactivation by both methods primarily shares the same mechanism, DNA demethylation. In order to examine whether DNA demethylation affects the growth of cancer cells, we have established a tetracycline inducible system that can regulate the expression of MBD‐TET1‐CDwt in a prostate cancer cell line, LNCaP. The induction of MBD‐TET1‐CDwt demethylated and upregulated glutathione S‐transferase pi 1 (GSTP1), one of the hypermethylated genes in prostate cancer. In accordance with the reactivation of methylated genes, induction of MBD‐TET1‐CDwt extensively suppressed the growth of LNCaP cells through G1/S arrest. These results clearly indicate that TET oxidase activity recruited at methyl‐CpG sites through MBD induces reactivation of hypermethylated genes by DNA demethylation and allows us to analyze the effect of only global DNA demethylation in a wide variety of cancer cells.

Pheochromocytomas and paragangliomas are neuroendocrine tumors which arise from adrenal medulla, and sympathetic or parasympathetic nerves, respectively. Hereditary cases afflicted by both or either pheochromocytomas and paragangliomas have been reported: these are called hereditary pheochromocytoma/paraganglioma syndromes (HPPS). Many cases of HPPS are caused by mutations of one of the succinate dehydrogenase (SDH) genes; mainly SDHB and SDHD that encode subunits for the mitochondrial respiratory chain complex II. In this study, we investigated mutations of SDH genes in six HPPS patients from four Japanese pedigrees using peripheral blood lymphocytes (from one patient with pheochromocytoma and five patients with neck paraganglioma) and tumor tissues (from two patients with paraganglioma). Results showed that all of these pedigrees harbor germline mutations in one of the SDH genes. In two pedigrees, a novel IVS2-2AC mutation in SDHB, at the acceptor-site in intron 2, was found, and the tumor RNA of the patient clearly showed frameshift caused by exon skipping. Each of the remaining two pedigrees harbors a reported missense mutation, R242H in SDHB or G106D in SDHD. Importantly, all these mutations are heterozygous in constitutional DNAs, and two-hit mutations were evident in tumor DNAs. We thus conclude that the newly identified IVS2-2AC mutation in SDHB is responsible for HPPS. The novel mutation revealed by our study may contribute to improvement of clinical management for patients with HPPS.

The anti-tumor activity of gemcitabine (GEM) has been clinically proven in several solid tumors, including pancreatic cancer, biliary tract cancer, urinary bladder cancer, and non-small cell lung cancer. However, problems remain with issues such as acquisition of chemoresistance against GEM. GEM is activated after phosphorylation by deoxycytidine kinase (DCK) inside of the cell; thus, DCK inactivation is one of the important mechanisms for acquisition of GEM resistance. We previously investigated the DCK gene in multiple GEM resistant cancer cell lines and identified frequent inactivating mutations. In this study, we identified two crucial genetic alteration in DCK. (1) A total deletion of DCK in RTGBC1-TKB, an acquired GEM resistant cell line derived from a gall bladder cancer cell line TGBC1-TKB. (2) An E197K missense alteration of DCK in MKN28, a gastric cancer cell line; its acquired GEM resistant cancer cell line, RMKN28, showed a loss of the normal E197 allele. We introduced either normal DCK or altered DCK_E197K into RMKN28 and proved that only the introduction of normal DCK restored GEM sensitivity. Furthermore, we analyzed 104 healthy volunteers and found that none of them carried the same base substitution observed in MKN28. These results strongly suggest that (1) the E197K alteration in DCK causes inactivation of DCK, and that (2) loss of the normal E197 allele is the crucial mechanism in acquisition of GEM resistance in RMKN28.

Pancreatic cancer is a highly lethal disease with a poor prognosis; the molecular mechanisms of the development of this disease have not yet been fully elucidated. N-myc downstream regulated gene 2 ( NDRG2 ), one of the candidate tumor suppressor genes, is frequently downregulated in pancreatic cancer, but there has been little information regarding its expression in surgically resected pancreatic cancer specimens. We investigated an association between NDRG2 expression and prognosis in 69 primary resected pancreatic cancer specimens by immunohistochemistry and observed a significant association between poor prognosis and NDRG2-negative staining ( P = 0.038). Treatment with trichostatin A, a histone deacetylase inhibitor, predominantly up-regulated NDRG2 expression in the NDRG2 low-expressing cell lines (PANC-1, PCI-35, PK-45P, and AsPC-1). In contrast, no increased NDRG2 expression was observed after treatment with 5-aza-2′ deoxycytidine, a DNA demethylating agent, and no hypermethylation was detected in either pancreatic cancer cell lines or surgically resected specimens by methylation specific PCR. Our present results suggest that (1) NDRG2 is functioning as one of the candidate tumor-suppressor genes in pancreatic carcinogenesis, (2) epigenetic mechanisms such as histone modifications play an essential role in NDRG2 silencing, and (3) the expression of NDRG2 is an independent prognostic factor in pancreatic cancer.

DNA demethylating agents are useful therapeutic drugs for human cancer; 5-aza-2’-deoxycytidine and 5-azacytidine for myelodysplastic syndrome are good examples. They not only induce DNA demethylation but also have significant cytostatic and cytotoxic effects. However, precise mechanisms for anticancer activity of these demethylating reagents have yet to be established, mainly due to the lack of method to induce only DNA demethylation. Here we show that a fusion protein comprising the methyl-CpG binding domain (MBD) and the catalytic domain of Ten-eleven translocation protein 1 (TET1-CD) globally demethylates and upregulates a number of methylated genes. Gene expression microarray analyses using human embryonic kidney cell line 293T indicate that cells expressing wild-type (wt) TET1 catalytic domain with MBD (MBD-TET1-CDwt) upregulates more genes than ones expressing TET1-CDwt without MBD (TET1-CDwt) or catalytically inactive TET1-CD mutant (mut) with MBD (MBD-TET1-CDmut) and their upregulated genes frequently contained CpG islands (CGIs) within ± 1,000-bp of the transcription start site (TSS). Interestingly, 65% of genes upregulated 5-fold or more by MBD-TET1-CDwt were also reactivated after treatment with 5-azacytidine, DNA demethylating agent. These results suggested a fact that gene reactivation by both methods was primarily based on DNA demethylation. In order to examine growth inhibitory effects of DNA demethylation to cancer cells, we utilized a tetracycline inducible system to regulate the expression of MBD-TET1-CDwt using a prostate cancer cell line. Induction of MBD-TET1-CDwt demethylated and upregulated the glutathione S-transferase pi 1 (GSTP1), one of the hypermethylated genes in prostate cancer. In accordance with reactivation of methylated genes, induction of MBD-TET1-CDwt extensively suppressed the growth of LNCaP cells. Flow cytometry analysis showed decreased cells in S phase and increased cells in G1 phase by MBD-TET1-CDwt expression. Our present results clearly indicate that TET oxidase activity recruited at methyl-CpG sites through MBD induces reactivation of hypermethylated genes by DNA demethylation, and that our methods allow us to analyze the effects of global DNA demethylation in a wide variety of cancer cells. Citation Format: Shinichi Fukushige, Yasuhiko Mizuguchi, Kanchan Chakma, Yuriko Saiki, Akira Horii. Targeted TET oxidase activity through methyl-CpG binding domain extensively suppresses cancer cell proliferation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4432.

Ten-Eleven Translocation (TET) proteins play an important role in regulating DNA methylation fidelity and their inactivation contributes to the DNA hypermethylation phenotype in cancer; they are Fe²+- and 2-oxoglutarate-dependent dioxygenases that successively oxidize 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) and these oxidized methylcytosines are important intermediates in the process of 5mC demethylation. TET proteins convert 5mC to 5hmC in vitro, but it is difficult to explore the process of DNA demethylation and their effects on endogenous hypermethylated genes in cells. In this study, we tried to develop a system that accumulates TET oxidase activity at hypermethylated promoters. To accomplish this, we constructed a fusion protein-producing vector consisting of methyl-CpG binding domain (MBD) and TET1 catalytic domain (TET1 CD) and asked whether this fusion protein (MBD-TET1 CD) could lead to DNA demethylation and gene reactivation. We first prepared DNA constructs that contain wild-type (wt) TET1 CD as well as catalytically inactive TET1 CD mutant (mut) with or without MBD from MBD2 protein and then transfected each construct into human embryonic kidney cell line 293T. We isolated stably transfected 293T cell lines and analyzed the expression of genes transcriptionally silenced by DNA hypermethylation using RT-PCR. Surprisingly, only plasmids containing TET1 CDwt reactivated silenced MAL, SOX17, TRH, MT1M, and MLH1 genes in a MBD dependent manner. To clarify the mechanisms of the antisilencing activities in clones stably expressed MBD-TET1 CDwt, we examined the CpG islands in MAL, TRH, and MT1M promoters by genomic sequencing after bisulfite modifications. Almost all CpG sites were methylated in parental cell line 293T, a TET1 CDwt clone, a TET1 CDmut clone, and a MBD-TET1 CDmut clone. On the other hand, MBD-TET1 CDwt clones showed an extensive demethylation at CpG islands of all three genes. In addition, because bisulfite sequencing does not distinguish between 5mC and 5hmC, we converted 5hmC to glucosylated form and discriminated between 5mC and 5hmC using restriction enzymes MspI and HpaII. Quantitative real time PCR analysis clearly demonstrated that MBD-TET1 CDwt promoted demethylation at CpG sites with some 5hmC bases. We further examined the changes in global gene expression in stable cell lines containing different TET constructs by microarray analyses. All top 50 genes upregulated by MBD-TET1 CDwt-stably expressing cell lines contained CpG islands and interestingly, 43 of top 50 genes were also upregulated after treatment with DNA demethylating agent, 5-azacytidine. These results suggest that specific recruitment of TET oxidase activity on hypermethylated gene promoters induces DNA demethylation and promotes reactivation of epigenetically silenced genes. Citation Format: Shinichi Fukushige, Yasuhiko Mizuguchi, Akira Horii. TET oxidase activity accumulated on methyl-CpG sites extensively upregulates methylated genes through DNA demethylation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 396. doi:10.1158/1538-7445.AM2014-396

It is well known that inactivation of tumor suppressor gene (TSG) by promoter hypermethylation plays an important role during the development and progression of cancer. NDRG2 (N-myc downstream regulated gene 2) is considered to be one of the candidate TSGs. Significant down-regulation in various human cancers were observed, but the molecular mechanisms of reduced expression and the ways to carcinogenesis are largely not well understood. To elucidate the mechanisms in expressional suppression of NDRG2, we studied the methylation status of the putative promoter region in this gene. NDRG2 has two promoters; we first found that the mRNA transcription predominantly starts from the promoter containing exon 1b in organs of the digestive system. Then the expression level of NDRG2 was analyzed by quantitative real-time RT-PCR using 20 colorectal, 6 gastric, and 5 pancreatic cancer cell lines; many cell lines showed reduced expression. Bisulfite modification followed by nucleotide sequencing analyses in the putative promoter region revealed that the methylation status correlated with the suppressed expression. We extended our analysis to the primary tumors by immunohistochemical examination to elucidate clinical significance of suppressed expression of NDRG2 in tumorigenesis; matched normal and cancerous tissues from cancer patients with digestive system were analyzed and observed suppressed expression of NDRG2 in 19 of 20 colorectal, 8 of 10 gastric, and 85 of 86 pancreatic cancer specimens. We then designed a set of primer pairs for methylation specific PCR and examined the relationship between expression level of NDRG2 and promoter hypermethylation in resected primary tumor specimens. Association between methylation status and clinicopathologic features are now studied and the newly obtained results will be presented. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4933.

The jack-up rig is set on the seabed and supported on the seabed ground. There are many problems arising from the seabed ground (such as penetration and punch-through of footing, liquefaction of supporting sand foundation due to earthquake and wave, scouring due to wave and current, suction force on bottom being freed, etc.), which are extremely important in connection with the basic planning and the operation of a jack-up rig and might have been the major cause of its accidents.Of these problems, in this paper, an analysis method of punch-through of footing and a method for reducing suction force are discussed.The analysis method of punch-through of footing is first described. It was used in analyzing an actual example in certain waters based on the local soil and load conditions and the results were compared with the actual values. The main conclusions reached are: (1) an analysis method of punch-through has been proposed, and (2) an actual example of punch-through was analyzed by this method based on the actual soil and load conditions, resulting in good agreement with the actual values.Next, a natural inflow suction breaker was used as a means for reducing suction force. The footing is installed with connection pipes that are allowed to naturally run sea water existing over the footing top therethrough under the suction produced on the bottom being freed, thereby reducing such suction force. A reconsolidated sea-silt ground was prepared in a soil tank. An about 1/20-scaled footing model was placed thereon to penetrate into it for a bottom freeing test. In this test, the suction force, the amount of pullout of footing, the amount of water flow through the suction breaker and the suction on the footing bottom were measured as changing the location of the suction breaker nozzles, water depth and footing pullout speed. The main conclusions obtained in this test are: (1) it is desirable to arrange the suction breaker nozzles evenly around the area close to the footing edge, (2) the relation between the efficiency of the suction breaker and the inflow rate of water into the void under the footing is almost proportional, and (3) the efficiency of the suction breaker has an optimum pullout speed.

Semi-submersible rigs are more versatile than ship shaped drilling rigs for operations in deep water areas due to its better ship motion characteristics.Presently, a number of semi-submersible rigs used as the production platforms for small-sized oil fields are increasing.However floating rigs including semi-submersible sometime have difficulties in coping with environmental factors such as deeper working water depth and harsh meteorological condition.Workability of semi-submersible rigs utilized in the areas can be calculated based on operating limited value of the rig behavior constructed elements which consist of riser, mooring and hull. An optimum system as well as operational safety can be determined by maximizing the workability in the field.This paper shows the outlines of; (1)analysis of consisting elements, (2)spectral analysis method, (3)calculating method of workability with irregular response.The computer analysis is used to accurately calculate workability of the semi-submersible rig operation in relation to environmental condition in the field.As the results of above methods and analysis, the optimum system of the semi-submersible rig for the preselected field can be determined.