Aberrant expression of krUppel-like factor 6 protein in colorectal cancers

AIM: To investigate whether krUppel-like factor 6 (KLF6) plays an important role in the development and/or progression of colorectal cancer. METHODS: A total of 123 formalin-fixed and paraffin-embedded colorectal cancer specimens were analyzed by immunohistochemistry using tissue microarray for the expression of KLF6 protein. The specimens were collected over a 3-year period in the laboratories at our large teaching hospital in Seoul, Republic of Korea. The correlation of KLF6 expression with clinicopathologic parameters was analyzed by x2 test and Bartholomew test. RESULTS: Normal colonic epithelium showed weak to moderate expression of KLF6, whereas reduced KLF 6 expression or loss of KLF6 expression was seen in 45 (36.6%) of the 123 colorectal carcinoma specimens. Interestingly, aberrant expression of KLF6 was detected in 25 (43.1%) of 58 cases with metastasis to regional lymph node and in 31 (47.0%) of 66 tumors more than 5 cm in size. Statistically, loss of KLF6 expression was significantly associated with tumor size (P<0.05). However, there was no significant correlation between KLF6 expression and Dukes' stage (Bartholomew test, P>0.05), tumor location and lymph node metastasis (x2 test, P> 0.05). CONCLUSION: Loss of KLF6 expression may be a common and early event in colorectal carcinogenesis.     

Aberrant expression of krüppel-like factor 6 protein in colorectal cancers

AIM: To investigate whether kr(U)ppel-like factor 6 (KLF6)plays an important role in the development and/or progression of colorectal cancer.METHODS: A total of 123 formalin-fixed and paraffinembedded colorectal cancer specimens were analyzed by immunohistochemistry using tissue microarray for the expression of KLF6 protein. The specimens were collected over a 3-year period in the laboratories at our large teaching hospital in Seoul, Republic of Korea. The correlation of KLF6 expression with clinicopathologic parameters was analyzed by x2 test and Bartholomew test.RESULTS: Normal colonic epithelium showed weak to moderate expression of KLF6, whereas reduced KLF 6expression or loss of KLF6 expression was seen in 45(36.6%) of the 123 colorectal carcinoma specimens.Interestingly, aberrant expression of KLF6 was detected in 25 (43.1%) of 58 cases with metastasis to regional lymph node and in 31 (47.0%) of 66 tumors more than 5 cm in size. Statistically, loss of KLF6 expression was significantly associated with tumor size (P＜0.05).However, there was no significant correlation between KLF6 expression and Dukes' stage (Bartholomew test,P＞ 0.05), tumor location and lymph node metastasis (x2test, P＞ 0.05).CONCLUSION: Loss of KLF6 expression may be a common and early event in colorectal carcinogenesis.     

SIRT6, a protein with many faces

Sirtuins are NAD⁺ dependent deacylases enzymes. There are seven mammalian sirtuins, SIRT1–SIRT7, which are localized to different cellular compartments and are capable of diverse catalytic activities. SIRT6 is a key regulator of healthy ageing. In the past decade our understanding of SIRT6 significantly increased in many different aspects. We know its cellular localization, catalytic activities, substrates and the pathways it is involved in. This review discusses the recent discoveries regarding the SIRT6 enzyme.     

Are many colorectal cancers due to missed adenomas?

BackgroundAn unknown number of colorectal cancers could be due to missed adenomas during previous endoscopy. Data in the literature are sparse. A large cross-sectional study was done in a prospective database of all patients diagnosed with colorectal cancer.MethodsAll consecutive endoscopies over a period of 15 years, in which colorectal cancer was diagnosed were included. All patients who underwent more than one endoscopy and in whom ultimately cancer was diagnosed were studied separately.ResultsColorectal cancer was diagnosed in 835 patients. Twenty-five patients underwent a previous endoscopy without a cancer diagnosis. These 25 patients were divided into three groups according to the time between the endoscopy in which the cancer was detected and the previous endoscopy. Five out of these 25 patients underwent regular surveillance. Only 11 patients had no argument for regular follow-up. Assuming that these cancers developed from an adenoma than only 11 out of 835 (1.3%) cancers were missed in the adenoma phase. There was no difference in the size of the tumour between the three groups of patients.ConclusionIn normal daily practice, only a small number of clinically important adenomas are missed. The problem of missed adenomas probably is being exaggerated.     

Loss of activin receptor type 2 protein expression in microsatellite unstable colon cancers

BACKGROUND & AIMS: Colorectal tumors manifesting high-frequency microsatellite instability (MSI-H) develop genetically as a consequence of mutations in genes harboring repetitive DNA sequences. The activin type 2 receptor (ACVR2), possessing 2 polyadenine coding sequences, was identified as a mutational target, but it is not clear if expression is abrogated. Here, we analyzed MSI-H colorectal cancers for ACVR2 mutation and expression to assess if biallelic inactivation occurs. METHODS: All 54 MSI-H colon cancers and 20 random microsatellite stable (MSS) tumors from a population-based cohort of 503 patients were analyzed for mutations in 2 A(8) tracts (exon 3 and 10) of ACVR2 and the A(10) tract of transforming growth factor beta receptor 2 (TGFBR2). Additionally, we sequenced exon 10 of ACVR2 in select cancers. ACVR2 expression was determined by immunohistochemistry using an antibody targeting an epitope beyond the predicted truncated protein. RESULTS: Forty-five of 54 MSI-H cancers (83%) showed mutation (A(8) to A(7)) in the polyadenine tract of exon 10 compared with no MSS tumors. Of tumors with mutant ACVR2, 62% lacked protein expression but all MSS and MSI-H tumors with wild-type ACVR2 expressed protein. We found no evidence of loss of heterozygosity at the ACVR2 locus in MSS tumors. Comparatively, 69% of MSI-H cancers had frameshift mutation in TGFBR2. CONCLUSIONS: ACVR2 mutations are highly frequent in MSI-H colon cancers and in most cases cause loss of ACVR2 expression, indicating biallelic inactivation of the gene. Loss of activin signaling through mutation of ACVR2, similar to observations with TGFBR2, may be important in the genesis of MSI-H colorectal cancer.     

C-reactive protein as a biomarker for urological cancers

Systemic inflammation has been linked with the progression of cancer, and, in patients with urological cancers, the presence of a systemic inflammatory response is thought to be indicative of poor prognosis. C-reactive protein (CRP) is an acute-phase reactant, the levels of which can be objectively measured using standardized reliable assays, and a useful marker of systemic inflammation. CRP levels have been shown to predict survival in patients with urological cancers, including renal cell carcinoma, upper urinary tract and bladder cancers, and prostate cancer, and the incorporation of CRP into prognostic models for urological cancers improves the models' predictive accuracy. Furthermore, the kinetics of CRP release and the analysis of dynamic changes in CRP concentrations over time, could predict tumor aggressiveness and potential treatment efficacy. For instance, in long-term survivors of testicular cancer, CRP is associated with the risk of late complications, such as cardiovascular disease, and with the development of second non-germ-cell cancer. CRP could, therefore, be an important biomarker for urological cancers.     

S-adenosyl methionine regulates ubiquitin-conjugating enzyme 9 protein expression and sumoylation in murine liver and human cancers

Ubiquitin-conjugating enzyme 9 (Ubc9) is required for sumoylation and is overexpressed in several malignancies, but its expression in hepatocellular carcinoma (HCC) is unknown. Hepatic S-adenosyl methionine (SAMe) levels decrease in methionine adenosyltransferase 1A (Mat1a) knockout (KO) mice, which develop HCC, and in ethanol-fed mice. We examined the regulation of Ubc9 by SAMe in murine liver and human HCC, breast, and colon carcinoma cell lines and specimens. Real-time polymerase chain reaction and western blotting measured gene and protein expression, respectively. Immunoprecipitation followed by western blotting examined protein-protein interactions. Ubc9 expression increased in HCC and when hepatic SAMe levels decreased. SAMe treatment in Mat1a KO mice reduced Ubc9 protein, but not messenger RNA (mRNA) levels, and lowered sumoylation. Similarly, treatment of liver cancer cell lines HepG2 and Huh7, colon cancer cell line RKO, and breast cancer cell line MCF-7 with SAMe or its metabolite 5'-methylthioadenosine (MTA) reduced only Ubc9 protein level. Ubc9 posttranslational regulation is unknown. Ubc9 sequence predicted a possible phosphorylation site by cell division cycle 2 (Cdc2), which directly phosphorylated recombinant Ubc9. Mat1a KO mice had higher phosphorylated (phospho)-Ubc9 levels, which normalized after SAMe treatment. SAMe and MTA treatment lowered Cdc2 mRNA and protein levels, as well as phospho-Ubc9 and protein sumoylation in liver, colon, and breast cancer cells. Serine 71 of Ubc9 was required for phosphorylation, interaction with Cdc2, and protein stability. Cdc2, Ubc9, and phospho-Ubc9 levels increased in human liver, breast, and colon cancers. Conclusion: Cdc2 expression is increased and Ubc9 is hyperphosphorylated in several cancers, and this represents a novel mechanism to maintain high Ubc9 protein expression that can be inhibited by SAMe and MTA. (HEPATOLOGY 2012;56:982-993).     

Prognostic significance of ANO1 expression in cancers

Background:Anoctamin-1 (ANO1) plays a pivotal role in cancer progression. A meta-analysis was conducted to assess the potential prognostic role of ANO1 in cancers.Methods:A total of 1760 patients from 7 eligible studies were included into the analysis. Pooled hazard ratios or odds ratios were extracted and calculated with a random-effects model, and analyses of heterogeneity bias were conducted.Results:Our results showed that over expression of ANO1 was significantly correlated with poor overall survival in all cancers (HR = 1.52; 95% CI: 1.19–1.92; P = .0006). Subgroup analysis indicated that there was a significant association between over expression of ANO1 and poor prognosis breast cancer (HR = 3.24; 95% CI: 1.74–6.04), head and neck squamous cell carcinoma (HR = 1.14; 95% CI: 1.00–1.30), esophageal squamous cell carcinoma (HR = 1.93; 95% CI: 1.07–3.50), gastric cancer (HR = 1.62; 95% CI: 1.12–2.34) and colorectal cancer (HR = 1.38; 95% CI: 1.03–1.85). In addition, over expression of ANO1 was not associated with TNM stage, histological grade, lymph node metastasis, tumor size, age and gender. However, ANO1 was significantly associated with human epidermal growth factor receptor 2, but not associated with progesterone receptor or estrogen receptor in breast cancer.Conclusions:Our results indicate that ANO1 can be a predictive factor for prognosis of cancer.     

Defective hMSH2/hMLH1 protein expression is seen infrequently in ulcerative colitis associated colorectal cancers

BACKGROUND: Ulcerative colitis is associated with an increased risk of colorectal cancer above that of the normal population. The relative risk correlates with the extent and duration of the disease but the genetic basis of ulcerative colitis associated cancer risk is not known. AIMS: To assess the prevalence of microsatellite instability and mismatch repair gene abnormalities in ulcerative colitis associated colorectal cancer. PATIENTS: Forty six patients with colorectal cancer, with a previous histological diagnosis of ulcerative colitis. METHODS: The frequency of microsatellite instability and/or immunohistochemical expression of hMSH2 and hMLH1 was assessed. Thirty three cases were investigated using both approaches. RESULTS: Although 6/41 (14.6%) cases showed microsatellite instability at one or more markers, only one case (2. 4%) exhibited high level instability (at least two markers affected). Of 38 cases which were assessed using antibodies against hMSH2 and hMLH1, only one case (2.6%) showed loss of expression. This case, which showed loss of hMSH2 expression, was the same case which exhibited high level microsatellite instability. The 33 cases which were investigated using both approaches showed that loss of expression of either hMSH2 or hMLH1 was not seen in any case which exhibited microsatellite instability in no more than one marker. CONCLUSIONS: This study suggests that both high level microsatellite instability and loss of expression of hMSH2/hMLH1 are infrequent events in ulcerative colitis associated colorectal cancers. Low level microsatellite instability was not associated with loss of expression of either hMSH2 or hMLH1.     

High expression of anti-apoptotic protein Bcl-2 is a good prognostic factor in colorectal cancer: Result of a metaanalysis

AIM To systematically evaluate the prognostic-predictive capability of Bcl-2 in colorectal cancer(CRC).METHODS A systematic literature search was conducted using Pub Med,Web of Science and EMBASE databases. Any eligible study must meet the following criteria:(1) bcl-2 expression was evaluated in human CRC tissues by immunohistochemistry;(2) assessment of the relationships between bcl-2 expression and overall survival(OS),disease free survival(DFS),recurrent free survival(RFS) or clinic-pathological characteristics of CRC was included;(3) sufficient information was provided to estimate the hazard ratio(HR) or odds ratio and their 95% confidence intervals(CIs); and(4) the study was published in English. The impact of Bcl-2 expression on survival of CRC patients were evaluated through this meta-analysis.RESULTS A total of 40 eligible articles involving 7658 patients were enrolled in our final analysis. We drew the conclusion that Bcl-2 high expression was significantly correlated with favorable OS(pooled HR = 0.69,95%CI: 0.55-0.87,P = 0.002) and better DFS/RFS(pooled HR = 0.65,95%CI: 0.50-0.85,P = 0.001). Additionally,the subgroup analysis suggested that Bcl-2 overexpression was significantly associated withprognosis(OS) especially in patients came from Europe and America but not Asian and patients who did not receive any adjuvant therapy before surgery. Finally,our present results indicated that expression of bcl-2 protein was associated with high differentiation grade and A/B Ducks' stage. CONCLUSION Bcl-2 high expression was significantly correlated with favorable OS and better DFS/RFS. Hence,we propose that Bcl-2 may be a valuable prognostic-predictive marker in CRC.     

Tbx2蛋白在胰腺癌组织和细胞中的表达及其意义

目的 检测Tbx2蛋白在胰腺癌组织及细胞中的表达,并探讨Tbx2表达与胰腺癌临床和病理的关系.方法 运用免疫组化SP法,检测13例正常胰腺组织和49例胰腺癌组织中Tbx2蛋白的表达,并分析其表达水平与胰腺癌临床病理因素间的关系;采用RT-PCR和Western印迹检测Tbx2在胰腺癌细胞株SW1990中的表达.结果 癌组织中Tbx2表达率(34/49,69.4%)高于正常胰腺组织(1/13,7.7%),P＜0.01;Tbx2的表达水平与肿瘤细胞分化程度、TNM分期有关,与患者性别、年龄以及肿瘤发生部位无关;胰腺癌细胞株SW1990中亦有Tbx2表达.结论 Tbx2蛋白在胰腺癌组织和细胞中表达水平特异性升高,并与肿瘤细胞分化程度、TNM分期有关.Tbx2参与了胰腺癌的发生发展.     

High interobserver variability in endosonographic staging of upper gastrointestinal cancers

Mostly based on results of experienced examiners, endoscopic ultrasound (EUS) has been reported to be highly accurate for locoregional staging of upper gastrointestinal cancers. However, data on interobserver variability among EUS examiners, depending on their experience levels, is sparse. A study was therefore conducted to analyse well-documented videotapes of EUS examinations of 108 patients with resected cancers of the esophagus (n = 55) or stomach (n = 53) in a strictly blinded fashion by 5 examiners, all of whom were experienced in EUS (more than 300 examinations: n = 3, more than 100 examinations: n = 2). Besides the individual accuracy rates in cancer staging, a kappa-statistic was calculated to check for interobserver variability. Under the conditions described, the staging accuracy of all investigators was lower than that usually achieved under clinical routine conditions. The mean T staging accuracy was 41.1 % +/- 9.4 and 46.9 % +/- 5.4 in gastric and esophageal cancers, respectively. For N-staging the respective values were 47.9 % +/- 5.1 (stomach) and 67.7 % +/- 5.4 (oesophagus). Kappa-values were above 0.4 only in the staging of non-invasive esophagogastric tumours of the N0 and T1-category, corresponding to a fairly good agreement among the five investigators. Differences depending on experience levels could not be consistently found. Hence, it can be concluded that endosonographic cancer staging performed in a blinded manner results in a low accuracy and high interobserver variability even among experienced examiners.     

Reduced expression of cyclooxygenase 2 proteins in hereditary nonpolyposis colorectal cancers relative to sporadic cancers.

BACKGROUND & AIMS: Cyclooxygenase (COX) enzymes catalyze the conversion of arachidonic acid to prostaglandins. Evidence suggests that nonsteroidal anti-inflammatory drugs reduce the risk of colorectal cancer (CRC) and that this effect is mediated through COX inhibition. We analyzed and compared expression of the inducible COX-2 isoform in colorectal neoplasms from patients with hereditary nonpolyposis colorectal cancer (HNPCC), familial adenomatous polyposis (FAP), and sporadic CRC. Given that COX-2 is induced by transforming growth factor (TGF)-beta and that TGF-beta type II receptor (RII) mutations are found in HNPCCs, we determined the relationship between RII status and COX-2 expression. METHODS: COX-2 protein expression was determined in colorectal epithelia using immunohistochemistry and Western blotting. Patients with HNPCC had known mutations in hMLH1 or hMSH2 genes and/or met the Amsterdam criteria. In CRCs from HNPCC cases, mutations were sought in the coding region of the RII gene using the polymerase chain reaction. RESULTS: COX-2 was detected in adenomas from 2 of 3 HNPCC, 6 of 7 FAP, and 5 of 8 sporadic cases. In CRCs, COX-2 staining was found in 16 of 24 (67%) HNPCC vs. 24 of 26 (92%) sporadic cases (P = 0.035) and in 2 of 2 FAP cases. Staining intensity was reduced in HNPCCs compared with sporadic CRCs (P = 0.035). Staining localized to the cytoplasm of neoplastic cells; normal epithelial cells were negative for COX-2. Overexpression of COX-2 in CRCs relative to normal mucosa was confirmed by Western blotting. TGF-beta RII mutations were detected in 12 of 14 HNPCCs examined, including 3 of 4 COX-2-negative and 9 of 10 COX-2-positive cancers. CONCLUSIONS: The frequency and intensity of COX-2 expression was significantly reduced in HNPCCs relative to sporadic CRCs, and was not a consequence of RII mutations. Given that many HNPCCs express COX-2, inhibition of this enzyme may be an important strategy to prevent CRC in these patients.     

Prognostic significance of A-kinase interacting protein 1 expression in various cancers: A meta-analysis based on the Chinese population

Background:Cumulative evidence suggests that A-kinase interacting protein 1 (AKIP1) plays an important role in tumor progression. However, the prognostic value of AKIP1 expression in various cancers remains unclear. Here, we conducted a meta-analysis to evaluate the prognostic value of AKIP1 expression in patients with cancer.Methods:The PubMed, Web of Science, EMBASE, CNKI, and Wanfang databases were systematically searched to identify studies in which the effect of AKIP1 expression on prognosis (overall survival or disease-free survival) was investigated. Hazard ratios (HRs) with 95% confidence intervals (CIs) were combined to assess the effect of AKIP1 expression on patient survival. Odds ratios (ORs) with 95% CIs were pooled to estimate the association between AKIP1 expression and clinicopathological characteristics of patients with cancer.Results:Nineteen eligible studies, encompassing 3979 patients, were included in the meta-analysis. AKIP1 expression was negatively associated with overall survival (HR = 1.86, 95% CI: 1.58–2.18, P < .001) and disease-free survival (HR = 1.69, 95% CI: 1.53–1.87, P < .001) in patients with cancer. Moreover, AKIP1 overexpression was positively correlated with adverse clinicopathological features, such as tumor size (OR = 2.22, 95% CI: 1.67–2.94, P < .001), clinical stage (OR = 2.05, 95% CI: 1.45–2.90, P < .001), depth of tumor invasion (OR = 2.98, 95% CI: 2.21–4.02, P < .001), and degree of lymph node metastasis (OR = 2.12, 95% CI: 1.75–2.57, P < .001).Conclusions:High AKIP1 expression is an unfavorable prognostic biomarker and may serve as a potential therapeutic target in patients with cancer.     

Infrequent activation of mitogen-activated protein kinase in human colon cancers

BACKGROUND/AIMS: Mitogen-activated protein kinase (MAPK) is a downstream factor of the Ras-Raf-MAPK cascade and it is now considered to be a key molecule in signaling processes stimulated by growth factors and differentiation inducers. METHODOLOGY: We examined MAPK activity in 21 advanced colon cancers to investigate whether the MAPK cascade might play a role in the progression of colon cancers. RESULTS: MAPK activation (3.9-10.1-fold) was observed in 4 of 21 cases (18%), but 3 cases (75%, 3 of 4 cases) showed MAPK activation without ras mutation, thus suggesting that MAPK activation did not correlate with the presence of Ki-ras mutations in these cases. Other kinds of oncogene activation would be involved to MAPK activation in human colon cancers. In other cases MAPK activation was not detected or partly down-regulated. CONCLUSIONS: These findings suggest that positive and negative regulation of MAPK activity are associated with loss of normal growth control and may be involved in carcinogenesis of colon cancers.