KISS1 methylation and expression as predictors of disease progression in colorectal cancer patients

AIM:To examine the effect of aberrant methylation of the KISS1 promoter on the development of colorectal cancer(CRC)and to investigate reversing aberrant methylation of the KISS1 promoter as a potential therapeutic target.METHODS:KISS1 promoter methylation,mRNA expression and protein expression were detected by methylation-specific polymerase chain reaction(PCR),real-time quantitative PCR and Western blotting,respectively,in 126 CRC tissues and 142 normal colorectal tissues.Human CRC cells with KISS1 promoter hypermethylation and poor KISS1 expression were treated in vitro with 5-aza-2’-deoxycytidine(5-Aza-CdR).After treatment,KISS1 promoter methylation,KISS1 mRNA and protein expression and cell migration and invasion were evaluated.RESULTS:Hypermethylation of KISS1 occurred frequently in CRC samples(83.1%,105/126),but was infrequent in normal colorectal tissues(6.34%,9/142).Moreover,KISS1 methylation was associated with tumor differentiation,the depth of invasion,lymph node metastasis and distant metastasis(P<0.001).KISS1methylation was also associated with low KISS1 expression(P<0.001).Furthermore,we observed re-expression of the KISS1 gene and decreased cell migration after 5-Aza-CdR treatment in a CRC cell line.CONCLUSION:These data suggest that KISS1 is down-regulated in cancer tissues via promoter hypermethylation and therefore may represent a candidate target for treating metastatic CRC.     

Somatic molecular changes and histo-pathological features of colorectal cancer in Tunisia

AIM:To determine correlations between family history,clinical features and mutational status of genes involved in the progression of colorectal cancer(CRC).METHODS:Histo-pathological features and molecular changes[KRAS,BRAF and CTNNB1 genes mutations,microsatellite instability(MSI)phenotype,expression of mismatch repair(MMR)and mucin(MUC)5AC proteins,mutation and expression analysis of TP53,MLH1promoter hypermethylation analysis]were examined in a series of 51 unselected Tunisian CRC patients,10 of them had a proven or probable hereditary disease,on the track of new tumoral markers for CRC susceptibility in Tunisian patients.RESULTS:As expected,MSI and MMR expression loss were associated to the presence of familial CRC(75%vs 9%,P<0.001).However,no significant associations have been detected between personal or familial cancer history and KRAS(codons 12 and 13)or TP53(exons 4-9)alterations.A significant inverse relationship has been observed between the presence of MSI and TP53 accumulation(10.0%vs 48.8%,P=0.0335)in CRC tumors,suggesting different molecular pathways to CRC that in turn may reflect different environmental exposures.Interestingly,MUC5AC expression was significantly associated to the presence of MSI(46.7%vs 8.3%,P=0.0039),MMR expression loss(46.7%vs8.3%,P=0.0039)and the presence of familial CRC(63%vs 23%,P=0.039).CONCLUSION:These findings suggest that MUC5AC expression analysis may be useful in the screening of Tunisian patients with high risk of CRC.     

Sporadic Colon Cancer: Mismatch Repair Immunohistochemistry and Microsatellite Instability in Omani Subjects

Background Colorectal carcinoma (CRC) is the most common gastrointestinal malignancy in the world, and there are suggestions of a particularly high incidence in the Middle East, including those of African origin. Defects in DNA mismatch repair (MMR) systems are involved in the carcinogenesis of both sporadic and inherited human cancers. We assessed colonic cancers in an attempt to identify tumors with DNA MMR deficiency and microsatellite instability (MSI). Additionally, we tested the ability of cell cycle regulator p16 that effects cell proliferation and can be abrogated by hypermethylation of the promoter region. Methods We reviewed the charts of 756 patients who were referred to the Oman major colonoscopy unit of the Sultan Qaboos University Hospital and Royal Hospital from the years 2000 to 2004. Colon cancer tissue was assayed using immunohistochemistry for expression of hMLH1 and hMSH2, and a panel of five pairs of microsatellite primers (NR21, NR22, NR24, BAT25, and BAT26) for MSI-H analysis and additional dinucleotide markers (D17S250, D5S346, and D2S123) used for MSI-L. The expression status of MMR genes and MSI was correlated with cancer stage, location, and histology. A total of 49 tumors were analyzed for histopathology, MSI, and hMLH1/hMSH2 protein expression analysis. The methylation status of the p16 promoter was determined by methylation-specific polymerase chain reaction (PCR). Results The mean age for the carcinomas was 52.2 years and 53% of the patients were male. The majority of the tumors were left-sided. The information currently available indicates that there is an incidence of 4.7% colon cancer (49/1036) and 12.1% (126/1290) colon adenoma among the cases who underwent colonoscopy at these centers. The rate of MSI-H was 12.2% (n = 6), which appears to be the same as previously reported in literature. Eight of 49 tumors (16.3%) were MMR defective by IHC. Defects in the mismatch repair genes hMLH1 and hMSH2 were found in four (66.7%) and two (33.3%) of CRCs MSI-H cases, respectively. Defects in hMLH1 expression in tumors were commonly associated with moderate differentiation. The p16 promoter was methylated in 4% of tumors. Conclusion This is the first genetic study of CRC in this region of the world to demonstrate the incidence of MSI, p16 methylation, and hMLH1 and MSH2 expression in the Omani population. In addition, a relatively high frequency of CRC in younger age groups was noted, which is an important observation. The left-sided preponderance of MMR defective tumors was mostly associated with hMLH1, and with possible loss of hMSH2 expression, an observation that differs from studies on other populations. In conclusion, although the overall rate of CRC is unknown in this region, the frequency of MSI in CRC in this region appears to be the same as in Caucasians in the USA.     

Microsatellite instability is not an uncommon finding in adult de novo acute myeloid leukemia

To investigate the biologic relevance of microsatellite instability (MSI) in de novo acute myeloid leukemia (AML), 102 consecutive adult patients were analyzed by using a panel of seven microsatellites (BAT25, BAT26, D13S1267, D13S174, D2S123, D5S346 and Mdf15). Frame-shift mutations in the repetitive sequences in the coding region of MSH3, MSH6, BAX, TGFBRII and IGFRII were also investigated by using a fluorescent PCR-based assay. Methylation-specific PCR was used to determine the methylation status of hMLH1 in MSI+ cases. MSH3, MSH6 and MLH1 expression was also analyzed in 68 cases by means of real-time quantitative PCR. MSI was detected in 20 cases: 14 cases had MSI-high (instability of at least two microsatellite markers) and 6 cases corresponded to MSI-low (a single polymorphic marker with instability). Six MSI+ cases showed an associated MLL rearrangement (p=0.002). No single case showed a mutation in the repetitive sequences of the MSH3, MSH6, BAX, TGFBRII and IGFRII genes. Most samples displayed low mRNA levels of the repair genes. hMLH1 promoter was hypermethylated in five MSI+ cases. Overall survival analysis revealed no adverse effect of MSI positivity. These results suggest that MSI may be a common biologic finding in de novo AML.     

Fibulin-1 Is Downregulated Through Promoter Hypermethylation in Colorectal Cancer: A Consort Study

Fibulin-1 (FBLN1) is involved in the progression of some types of cancer. However, the role of FBLN1 in colorectal cancer (CRC) has not been examined. The purpose of this study was to understand the molecular mechanisms and clinical significance of FBLN1 inactivation in CRC.The expression of FBLN1 in CRC tissues and adjacent normal tissues was analyzed by immunohistochemical analysis and quantitative real-time polymerase chain reaction (qRT-PCR). Methylation-specific polymerase chain reaction (MSP) and bisulfite sequencing PCR (BSP) were performed to examine the methylation status of the FBLN1 gene promoter. Furthermore, the methylated level of FBLN1 was analyzed with the clinicopathological characteristics.Immunohistochemical analysis and qRT-PCR analysis showed that FBLN1 protein and messenger RNA (mRNA) levels in tumor tissues were both significantly decreased compared with that in adjacent nontumor tissues. The methylation rate of FBLN1 promoter was significantly higher in CRC tissues than that in adjacent nontumor tissues (P < 0.001). In addition, the correlation between FBLN1 hypermethylation, protein expression, and overall survival (OS) was statistically significant.Our results indicated that the FBLN1 gene may be a novel candidate of tumor suppressor gene in CRC, and that promoter hypermethylation of FBLN1 is an important reason for its downregulation and is also a good predictor of OS for CRC.     

Increased frequency and clinical significance of myeloid-derived suppressor cells in human colorectal carcinoma

AIM: To investigate the frequency and clinical significance of the myeloid-derived suppressor cells (MDSC) in human colorectal carcinoma (CRC).METHODS: Samples of peripheral blood and tumor tissue from 49 CRC patients were analyzed. Mononuclear cells were isolated by Ficoll-Hypaque density gradient centrifugation and were subjected to a flow cytometry-based immunophenotypic analysis.RESULTS: A considerable increase in the percentage of CD33⁺HLA-DR^- MDSCs was observed in the peripheral blood (1.89% ± 0.75%) and tumor tissues (2.99% ± 1.29%) of CRC patients as compared with that in the peripheral blood of healthy controls (0.54% ± 0.35%). This expanded CD33⁺HLA-DR^- subset exhibited immature myeloid cell markers, but not lineage markers, and showed up-regulation of CD18/CD11b expression as compared with the MDSCs from healthy donors. Further studies showed that the MDSC proportion in CRC peripheral blood was correlated with nodal metastasis(P = 0.023), whereas that in tumor tissues was correlated with nodal/distant metastasis (P = 0.016/P = 0.047) and tumor stage (P = 0.028), suggesting the involvement of MDSCs in CRC tumor development.CONCLUSION: Characterization of MDSCs in CRC suggests the clinical significance of circulating and tumor-infiltrating MDSCs and may provide new insights into the CRC immunotherapy targeting MDSCs.     

MGMT and MLH1 methylation in Helicobacter pylori-infected children and adults

AIM:To evaluate the association between Helicobacter pylori(H.pylori) infection and MLH1 and MGMT methylation and its relationship with microsatellite instability(MSI).METHODS:The methylation status of the MLH1 and MGMT promoter region was analysed by methylation specific methylation-polymerase chain reaction(MSPPCR) in gastric biopsy samples from uninfected or H.pylori-infected children(n = 50),from adults with chronic gastritis(n = 97) and from adults with gastric cancer(n = 92).MLH1 and MGMT mRNA expression were measured by real-time PCR and normalised to a constitutive gene(β actin).MSI analysis was performed by screening MSI markers at 4 loci(Bat-25,Bat-26,D17S250 and D2S123) with PCR;PCR products were analysed by single strand conformation polymorphism followed by silver staining.Statistical analyses were performed with either the χ 2 test with Yates continuity correction or Fisher’s exact test,and statistical significance for expression analysis was assessed using an unpaired Student’s t-test.RESULTS:Methylation was not detected in the promoter regions of MLH1 and MGMT in gastric biopsy samples from children,regardless of H.pylori infection status.The MGMT promoter was methylated in 51% of chronic gastritis adult patients and was associated with H.pylori infection(P < 0.05);this region was methylated in 66% of gastric cancer patients,and the difference in the percentage of methylated samples between these patients and those from H.pylori-infected chronic gastritis patients was statistically significant(P < 0.05).MLH1 methylation frequencies among H.pylori-infected and non-infected chronic gastritis adult patients were 13% and 7%,respectively.We observed methylation of the MLH1 promoter(39%) and increased MSI levels(68%) in samples from gastric cancer patients in comparison to samples from H.pylori-infected adult chronic gastritis patients(P < 0.001 and P < 0.01,respectively).The frequency of promoter methylation for both genes was higher in gastric cancer samples than in H.pylori-positiv     

Biliary diversion increases resting energy expenditure leading to decreased blood glucose level in mice with type 2 diabetes

Aims/IntroductionType 2 diabetes mellitus is a group of metabolism abnormalities in carbohydrates and energy. Our aim was to investigate resting energy expenditure (REE) and blood glucose changes after biliary diversion in mice with diabetes.Materials and MethodsMale mice with diabetes were randomly divided into biliary diversion and sham groups. REE was detected by indirect calorimetry, the levels of fasting blood glucose, total bile acids and triiodothyronine were analyzed. After mice were killed, the weight amount of brown adipose tissue (BAT) and gastrocnemius was measured, and the expression level of G protein‐coupled bile acid receptor and type 2 iodothyronine deiodinase in BAT and gastrocnemius were examined.ResultsThe two groups of mice were pair‐fed, the bodyweights (P < 0.001) and the fasting blood glucose level (P < 0.001) in the biliary diversion group significantly decreased 24 weeks after surgery. The intraperitoneal glucose tolerance test (P = 0.035) and oral glucose tolerance test (P = 0.027) showed improvement in glucose tolerance after surgery. The REE level significantly increased 24 weeks after surgery (P = 0.005), the levels of total bile acids (P = 0.014) and triiodothyronine (P < 0.001) increased at the 24th postoperative week. The weight ratio of BAT (P = 0.038) and gastrocnemius (P = 0.026) in the biliary diversion group were higher than that in the sham group. The expression of G protein‐coupled bile acid receptor in BAT (P < 0.001) and gastrocnemius (P = 0.003) were upregulated after surgery, and the type 2 iodothyronine deiodinase expression also increased in BAT (P = 0.015) and gastrocnemius (P = 0.015).ConclusionsThe REE level increased and the glucose metabolism improved in mice with diabetes after biliary diversion.     

Epigenetic silencing of LRRC3B in colorectal cancer

Objective. Tumor suppressor gene silencing via promoter hypermethylation is an important event in the pathogenesis of colorectal cancer (CRC). Some aberrant DNA hypermethylation has high tumor specificity, so it may contribute to early diagnosis of CRC. The objective of this study was to establish novel therapeutic and diagnostic strategies against CRC by identifying the novel methylation-related genes. Material andmethods. Two microarray-based approaches were used to identify novel methylation-related genes in CRC. We identified methylation-sensitive genes in colon cancer cell line SW1116 by comparing differential expression genes after treatment with the methylation inhibiting drug, 5-aza-2'-deoxycitidine (5-aza-dC) using gene expression microarray. Promoter microarray analysis was performed to identify cancer-specific, methylation-related genes in two patients with CRC. Gene promoter methylation was identified by methylation-specific polymerase chain reaction (PCR) (MSP) in primary CRC. Gene expression level was assessed using real-time PCR analysis. Results. By using gene expression microarray, up-regulation of 253 genes was detected in the CRC cell line, SW1116, after treatment with 5-aza-dC. Of the 253 genes identified by gene expression microarray analysis, LRRC3B (leucine-rich repeat containing 3B) was isolated as a potential methylation-specific gene by promoter microarray analysis. MSP analysis showed frequent methylation of LRRC3B in primary CRC (24/31 cases, 77%). In addition, the LRRC3B methylation intensity was significantly higher in cancer tissues than in the corresponding non-cancerous tissues. Decreased LRRC3B expression (17/31, 55%) was observed in the cancer tissues by real-time PCR. Conclusions.LRRC3B may be a novel methylation-sensitive tumor suppressor gene in CRC. LRRC3B methylation has significant tumor specificity and may be a biomarker of CRC.     

结直肠癌错配修复蛋白和微卫星不稳定检测的对比分析

目的目前最常用的筛查结直肠癌DNA错配修复基因缺失的方法是免疫组化检测错配修复（MMR）基因相关蛋白的表达,以及基于PCR检测多个微卫星位点判断有否微卫星不稳定（MSI）这2种方法,本研究主要目的是比较这二种检测之间的一致性,并对分子病理室作室内质量控制。 方法收集2014年8月至2015年10月湖北省肿瘤医院结直肠癌368例手术切除标本,免疫组化常规检测癌组织MLH1,PMS2,MSH2及MSH6这4种蛋白的表达。免疫组化显示任一蛋白完全缺失,判读为MMR蛋白缺失（dMMR）;如癌细胞4个MMR有多少不等的核着色,判读为MMR无缺失（pMMR）。选取其中的65例行PCR-毛细管电泳法检测MSI,其中28例为pMMR,37例为dMMR。然后对这65例组织用PCR毛细管电泳法检测Bethesda推荐的5个微卫星位点。比对这65例患者上述二种检测结果之间的一致性,并分析、整理其临床病理特征。 结果368例结直肠癌中有37例免疫组化结果为dMMR中,其余331例为pMMR。37例中剔除2例后对其中35例行毛细管PCR法检测,显示高频MSI者32例,微卫星稳定（MSS）者3例。选取331例中的28例行PCR检测,显示MSS者27例,MSI-H者1例。免疫组化法检测的敏感度和特异性分别为97.0%和90.0%,PCR检测结果的敏感度和特异性分别为91.4%和96.4%;二者总的一致性为93.7%。伴MSI的结直肠癌原发灶以右半结肠最多见（占48.6%）,病理形态以低分化腺癌伴淋巴细胞浸润和粘液分泌最常见,病理TNM分期以Ⅱ期和Ⅲ期为主。 结论免疫组化检测MMR蛋白和基于PCR的毛细管电泳法检测MSI二者的一致性高,其中免疫组化法可以作为临床初筛结直肠癌微卫星不稳定性的一种经济而便捷的方法,值得推广。     

Hypermethylation of TGF-β1 gene promoter in gastric cancer

AIM:To examine transforming growth factor-β1(TGF-β1)promoter methylation in gastric cancer and to determine if Helicobacter pylori(H.pylori)or interleukin(IL)-1β could induce TGF-β1 hypermethylation in vitro.METHODS:We examined the frequency and extent of TGF-β1 promoter methylation using methylationspecific PCR in the gastric tissues from 47 gastric cancer patients and 39 non-gastric cancer subjects.H.pylori infection was confirmed by a positive result from either a serological test,histological analysis or C13urea breath test.GES-1 and MKN-45 cells co-cultured with H.pylori or treated with IL-1β for 12,24 and 48 h in vitro tested the effects of H.pylori or IL-1β on TGF-1β.RESULTS:Twenty-four/forty-seven(51%)cases of gastric cancer(GC)tissues showed TGF-β1 promoter methylation,15/47(31.9%)cases of matched noncancerous gastric mucosa tissues from the GC patients,and 11/39(28%)case of the normal gastric mucosa tissues from non-GC subjects showed TGF-β1 promoter methylation(51%vs 28%,P<0.05).Significantly higher levels of methylation of TGF-β1 were found in the tumor tissues than in non-tumor tissues from GC patients(0.24±0.06 vs 0.17±0.04,P<0.05)and normal gastric tissues from non-GC subjects(0.24±0.06 vs 0.15±0.03,P<0.05).TGF-β1 methylation was found in 48.3% of H.pylori-positive gastric mucosal tissues whereas only 23.1% of H.pylori-negative gastric mucosal tissues showed TGF-β1 methylation(48.3%vs 23.1%,P<0.05).IL-1β appeared to induce a dose-dependent methylation of TGF-β1 and the strongest methylation was observed in GES-1 cells treated with 2.5 ng/mL of IL-1β for 48 h.Further studies showed that pre-treatment of GES-1 cells with 20ng/mL IL-1RA for 1 h could partially abolish the effect of IL-1β on TGF-β1 methylation.Infection of GES-1cells by H.pylori was not found to induce significant TGF-β1 promoter methylation.CONCLUSION:Our data revealed that TGF-1 promoter is methylated in GC patients.IL-1β may be an important mediator for H.pylori induced gene methylation during GC     

Immunohistochemical expression of SP-NK-1R-EGFR pathway and VDR in colonic inflammation and neoplasia

AIM:To determine the expression of neurokinin-1receptor(NK-1R),phosphorylated epidermal growth factor receptor(p EGFR),cyclooxygenase-2(Cox-2),and vitamin D receptor(VDR)in normal,inflammatory bowel disease(IBD),and colorectal neoplasia tissues from Puerto Ricans.METHODS:Tissues from patients with IBD,colitisassociated colorectal cancer(CAC),sporadic dysplasia,and sporadic colorectal cancer(CRC),as well as normal controls,were identified at several centers in Puerto Rico.Archival formalin-fixed,paraffin-embedded tissues were de-identified and processed by immunohistochemistry for NK-1R,p EGFR,Cox-2,and VDR.Pictures of representative areas of each tissues diagnosis were taken and scored by three observers using a4-point scale that assessed intensity of staining.Tissues with CAC were further analyzed by photographing representative areas of IBD and the different grades of dysplasia,in addition to the areas of cancer,within each tissue.Differences in the average age between the five patient groups were assessed with one-way analysis of variance and Tukey-Kramer multiple comparisons test.The mean scores for normal tissues and tissues with IBD,dysplasia,CRC,and CAC were calculatedand statistically compared using one-way analysis of variance and Dunnett’s multiple comparisons test.Correlations between protein expression patterns were analyzed with the Pearson’s product-moment correlation coefficient.Data are presented as mean±SE.RESULTS:On average,patients with IBD were younger(34.60±5.81)than normal(63.20±6.13,P0.01),sporadic dysplasia(68.80±4.42,P0.01),sporadic cancer(74.80±4.91,P0.001),and CAC(57.50±5.11,P0.05)patients.NK-1R in cancer tissue(sporadic CRC,1.73±0.34;CAC,1.57±0.53)and sporadic dysplasia(2.00±0.45)were higher than in normal tissues(0.73±0.19).p EGFR was significantly increased in sporadic CRC(1.53±0.43)and CAC(2.25±0.47)when compared to normal tissue(0.07±0.25,P0.05,P0.001,respectively).Cox-2 was significantly increased in sporadic colorectal cancer(2.20±0.23 vs 0.80±0.37 for normal tissues,P0.05).In comparison to normal(2.80±0.13)and CAC(2.50±0.33)tissues,VDR was significantly decreased in sporadic dysplasia(0.00±0.00,P0.001 vs normal,P0.001 vs CAC)and sporadic CRC(0.47±0.23,P0.001 vs normal,P0.001 vs CAC).VDR levels negatively correlated with NK-1R(r=-0.48)and p EGFR(r=-0.56)in normal,IBD,sporadic dysplasia and sporadic CRC tissue,but not in CAC.CONCLUSION:Immunohistochemical NK-1R and p EGFR positivity with VDR negativity can be used to identify areas of sporadic colorectal neoplasia.VDR immunoreactivity can distinguish CAC from sporadic cancer.     

Similar fecal immunochemical test results in screening and referral colorectal cancer

AIM: To improve the interpretation of fecal immunochemical test (FIT) results in colorectal cancer (CRC) cases from screening and referral cohorts. METHODS: In this comparative observational study, two prospective cohorts of CRC cases were compared. The first cohort was obtained from 10 322 average risk subjects invited for CRC screening with FIT, of which, only subjects with a positive FIT were referred for colonoscopy. The second cohort was obtained from 3637 subjects scheduled for elective colonoscopy with a positive FIT result. The same FIT and positivity threshold (OC sensor; ≥ 50 ng/mL) was used in both cohorts. Colonoscopy was performed in all referral subjects and in FIT positive screening subjects. All CRC cases were selected from both cohorts. Outcome measurements were mean FIT results and FIT scores per tissue tumor stage (T stage). RESULTS: One hundred and eighteen patients with CRC were included in the present study: 28 cases obtained from the screening cohort (64% male; mean age 65 years, SD 6.5) and 90 cases obtained from the referral cohort (58% male; mean age 69 years, SD 9.8). The mean FIT results found were higher in the referral cohort (829 ± 302 ng/mLvs 613 ± 368 ng/mL,P = 0.02). Tissue tumor stage (T stage) distribution was dif-ferent between both populations [screening population: 13 (46%) T1, eight (29%) T2, six (21%) T3, one (4%) T4 carcinoma; referral population: 12 (13%) T1, 22 (24%) T2, 52 (58%) T3, four (4%) T4 carcinoma], and higher T stage was significantly associated with higher FIT results (P 0.001). Per tumor stage, no significant difference in mean FIT results was observed (screening vs referral: T1 498 ± 382 ng/mL vs 725 ± 374 ng/mL, P = 0.22; T2 787 ± 303 ng/mL vs 794 ± 341 ng/mL, P = 0.79; T3 563 ± 368 ng/mLvs 870 ± 258 ng/mL,P = 0.13; T4 not available). After correction for T stage in logistic regression analysis, no significant differences in mean FIT results were observed between both types of cohorts (P = 0.10). CONCLUSION: Differences in T stage distribution largely explain differences in FIT results between screening and referral cohorts. Therefore, FIT results should be reported according to T stage.     

Incidence and functional consequences of hMLH1 promoter hypermethylation in colorectal carcinoma

Inactivation of the genes involved in DNA mismatch repair is associated with microsatellite instability (MSI) in colorectal cancer. We report that hypermethylation of the 5′ CpG island of hMLH1 is found in the majority of sporadic primary colorectal cancers with MSI, and that this methylation was often, but not invariably, associated with loss of hMLH1 protein expression. Such methylation also occurred, but was less common, in MSI− tumors, as well as in MSI+ tumors with known mutations of a mismatch repair gene (MMR). No hypermethylation of hMSH2 was found. Hypermethylation of colorectal cancer cell lines with MSI also was frequently observed, and in such cases, reversal of the methylation with 5-aza-2′-deoxycytidine not only resulted in reexpression of hMLH1 protein, but also in restoration of the MMR capacity in MMR-deficient cell lines. Our results suggest that microsatellite instability in sporadic colorectal cancer often results from epigenetic inactivation of hMLH1 in association with DNA methylation.     

Clinicopathologic and molecular features associated with patient age in gastric cancer

AIM: To compare characteristics and prognosis of gastric cancer based on age.METHODS: A retrospective study was conducted on clinical and molecular data from patients(n =1658) with confirmed cases of gastric cancer in Seoul National University Bundang Hospital(Seoul, South Korea) from 2003 to 2010 after exclusion of patients diagnosed with lymphoma, gastrointestinal stromal tumor, and metastatic cancer in the stomach. DNA was isolated from tumor and adjacent normal tissue,and a set of five markers was amplified by polymerase chain reaction to assess microsatellite instability(MSI). MSI was categorized as high, low, or stable if ≥ 2, 1, or 0 markers, respectively, had changed.Immunohistochemistry was performed on tissue sections to detect levels of expression of p53, human epidermal growth factor receptor(HER)-2, and epidermal growth factor receptor. Statistical analysis of clinical and molecular data was performed to assess prognosis based on the stratification of patients by age(≤ 45 and 45 years).RESULTS: Among the 1658 gastric cancer patients, the number of patients with an age ≤ 45 years was 202(12.2%; 38.9 ± 0.4 years) and the number of patients 45 years was 1456(87.8%; 64.1 ± 0.3 years).Analyses revealed that females were predominant inthe younger group(P 0.001). Gastric cancers in the younger patients exhibited more aggressive features and were at a more advanced stage than those in older patients. Precancerous lesions, such as atrophic gastritis and intestinal metaplasia, were observed less frequently in the older than in the younger group(P 0.001). Molecular characteristics, including overexpression of p53(P 0.001), overexpression of HER-2(P = 0.006), and MSI(P = 0.006), were less frequent in gastric cancer of younger patients. Cancer related mortality was higher in younger patients(P= 0.048), but this difference was not significant after adjusting for the stage of cancer.CONCLUSION: Gastric cancer is distinguishable between younger and older patients based on both clinicopathologic and molecular features, but stage is the most important predictor of prognosis.     

miR-132 inhibits colorectal cancer invasion and metastasis via directly targeting ZEB2

AIM:To investigate the biological role and underlying mechanism of miR-132 in colorectal cancer(CRC)progression and invasion.METHODS:Quantitative RT-PCR analysis was used to examine the expression levels of miR-132 in five CRC cell lines(SW480,SW620,HCT116,HT29 and LoVo)and a normal colonic cell line NCM460,as well as in tumor tissues with or without metastases.The KaplanMeier method was used to analyze the prognostic significance of miR-132 in CRC patients.The biological effects of miR-132 were assessed in CRC cell lines using the transwell assay.Quantitative RT-PCR and western blot analyses were employed to evaluate the expression of miR-132 targets.The regulation of ZEB2 by miR-132was confirmed using the luciferase activity assay.RESULTS:miR-132 was significantly down-regulated in the CRC cell lines compared with the normal colonic cell line(P<0.05),as well as in the CRC tissues withdistant metastases compared with the tissues without metastases(10.52±4.69 vs 23.11±7.84)(P<0.001).Down-regulation of miR-132 was associated with tumor size(P=0.016),distant metastasis(P=0.002),and TNM stage(P=0.020)in CRC patients.Kaplan-Meier survival curve analysis indicated that patients with low expression of miR-132 tended to have worse diseasefree survival than patients with high expression of miR-132(P<0.001).Moreover,ectopic expression of miR-132 markedly inhibited cell invasion(P<0.05)and the epithelial-mesenchymal transition(EMT)in CRC cell lines.Further investigation revealed ZEB2,an EMT regulator,was a downstream target of miR-132.CONCLUSION:Our study indicated that miR-132 plays an important role in the invasion and metastasis of CRC.     

Mucinous phenotype and CD10 expression of primary adenocarcinoma of the small intestine

AIM:To clarify the correlation with phenotypic expression,clinicopathological features,genetic alteration and microsatellite-instability status in small intestinal adenocarcinoma(SIA).METHODS:The cases of 47 patients diagnosed with primary SIAs that were surgically resected at our institution in 1975-2005 were studied.We reviewed clinicopathological findings(age,gender,tumor size,gross appearance,histological morphologic type,invasion depth,lymphatic permeation,venous invasion,and lymph node metastasis),and the immunohistochemical expression of MUC5 AC,MUC6,MUC2,CD10,and mismatch-repair(MMR) proteins(MLH1 and MSH2).We analyzed KRAS and BRAF gene mutations,and the microsatellite instability(MSI) status.The immunohistochemical staining of CD10,MUC2,MUC5 AC and MUC6 was considered positive when distinct staining in > 5% of the adenocarcinoma cells was recorded.To evaluate of MMR protein expression,we used adjacent normal tissue including lymphoid follicles,inflammatory cells,and stromal cells as an internal positive control.Sections without nuclear staining in the tumor cells were considered to have lost the expression of the respective MMR protein.RESULTS:There were 29 males and 18 females patients(mean age 59.9 years,range:23-87 years).Tumors were located in the duodenum in 14 cases(30%),the jejunum in 21 cases(45%),and the ileumin 12 cases(25%).A phenotypic expression analysis revealed 20 MUC2-positive tumors(42.6%),11 MUC5AC-positive(23.4%),4 MUC6-positive(8.5%),and 7 CD10-positive(14.9%).The tumor sizes of the MUC2(+) tumors were significantly larger than those of the MUC2(-) tumors(mean,5.7 ± 1.4 cm vs 4.7 ± 2.1 cm,P < 0.05).All three tumors with adenomatous component were positive for MUC2(P < 0.05).Polypoid appearance was seen significantly more frequently in the CD10(+) group than in the CD10(-) group(P < 0.05).The tumor size was significantly larger in the CD10(+) group than in the CD10(-) group(mean,5.9 ± 1.4 cm vs 5.0 ± 2.1 cm,P < 0.05).Of 34 SIAs with successfully obtained MSI data,4 were MSI-high.Of the 4 SIAs positive for both MUC5 AC and MUC2,3 showed MSI-H(75%) and 3 were mucinous adenocarcinoma(75%).KRAS mutations were detected in 4 SIAs.SIAs had KRAS mutation expressed only MUC2,but were negative for MUC5 AC,MUC6 and CD10.CONCLUSION:These findings suggest that the phenotypic expression of SIAs is correlated with their biological behavior,genetic alteration,and MSI status.