Omar Al-Obeed

Genome-wide mRNA and miRNA expression profiling reveal multiple regulatory networks in colorectal cancer

Despite recent advances in cancer management, colorectal cancer (CRC) remains the third most common cancer and a major health-care problem worldwide. MicroRNAs have recently emerged as key regulators of cancer development and progression by targeting multiple cancer-related genes; however, such regulatory networks are not well characterized in CRC. Thus, the aim of this study was to perform global messenger RNA (mRNA) and microRNA expression profiling in the same CRC samples and adjacent normal tissues and to identify potential miRNA-mRNA regulatory networks. Our data revealed 1273 significantly upregulated and 1902 downregulated genes in CRC. Pathway analysis revealed significant enrichment in cell cycle, integrated cancer, Wnt (wingless-type MMTV integration site family member), matrix metalloproteinase, and TGF-β pathways in CRC. Pharmacological inhibition of Wnt (using XAV939 or IWP-2) or TGF-β (using SB-431542) pathways led to dose- and time-dependent inhibition of CRC cell growth. Similarly, our data revealed up- (42) and downregulated (61) microRNAs in the same matched samples. Using target prediction and bioinformatics, ~77% of the upregulated genes were predicted to be targeted by microRNAs found to be downregulated in CRC. We subsequently focused on EZH2 (enhancer of zeste homolog 2 ), which was found to be regulated by hsa-miR-26a-5p and several members of the let-7 (lethal-7) family in CRC. Significant inverse correlation between EZH2 and hsa-miR-26a-5p (R2=0.56, P=0.0001) and hsa-let-7b-5p (R2=0.19, P=0.02) expression was observed in the same samples, corroborating the belief of EZH2 being a bona fide target for these two miRNAs in CRC. Pharmacological inhibition of EZH2 led to significant reduction in trimethylated histone H3 on lysine 27 (H3K27) methylation, marked reduction in cell proliferation, and migration in vitro. Concordantly, small interfering RNA-mediated knockdown of EZH2 led to similar effects on CRC cell growth in vitro. Therefore, our data have revealed several hundred potential miRNA-mRNA regulatory networks in CRC and suggest targeting relevant networks as potential therapeutic strategy for CRC.

MicroRNA-320 suppresses colorectal cancer by targeting SOX4, FOXM1, and FOXQ1

Colorectal cancer (CRC) is the third most common cancer causing high mortality rates world-wide. Delineating the molecular mechanisms leading to CRC development and progression, including the role of microRNAs (miRNAs), are currently being unravelled at a rapid rate. Here, we report frequent downregulation of the microRNA miR-320 family in primary CRC tissues and cell lines. Lentiviral-mediated re-expression of miR-320c (representative member of the miR-320 family) inhibited HCT116 CRC growth and migration in vitro, sensitized CRC cells to 5-Fluorouracil (5-FU), and inhibited tumor formation in SCID mice. Global gene expression analysis in CRC cells over-expressing miR-320c, combined with in silico prediction identified 84 clinically-relevant potential gene targets for miR-320 in CRC. Using a series of biochemical assays and functional validation, SOX4, FOXM1, and FOXQ1 were validated as novel gene targets for the miR-320 family. Inverse correlation between the expression of miR-320 members with SOX4, FOXM1, and FOXQ1 was observed in primary CRC patients specimens, suggesting that these genes are likely bona fide targets for the miR-320 family. Interestingly, interrogation of the expression levels of this gene panel (SOX4, FOXM1, and FOXQ1) in The Cancer Genome Atlas (TCGA) colorectal cancer data set (319 patients) revealed significantly poor disease-free survival in patients with elevated expression of this gene panel (P-Value: 0.0058). Collectively, our data revealed a novel role for the miR-320/SOX4/FOXM1/FOXQ1 axes in promoting CRC development and progression and suggest targeting those networks as potential therapeutic strategy for CRC.

Monopolar Electrosurgery through Single-Port Laparoscopy: A Potential Hidden Hazard for Bowel Burns

BACKGROUNDnSurveys indicate that up to 90% of general surgeons and gynecologists use monopolar radiofrequency during laparoscopy and 18% have experienced visceral burns. Monopolar electrosurgery compared with other energy sources is associated with unique characteristics and inherent risks and complications caused by inadvertent direct or capacitive coupling or insulation failure of instruments. These dangers become particularly important with the reemergence of single-port laparoscopy, which requires close proximity and crossing of multiple intraabdominal instruments outside the surgeons field of view.nnnSTUDY OBJECTIVESnTo determine the effects of monopolar electrosurgery on various tissues/organs during simulated single-port laparoscopic surgery in vitro and in vivo.nnnDESIGNnSimulation in a dry laboratory with fresh sheep liver, pig bowel and bowel in an anesthetized dog (Canadian Classification II-3).nnnSETTINGnUniversity-affiliated teaching hospital and animal facilities.nnnMEASUREMENTS AND MAIN RESULTSnWe used Valleylab Force 2 and FX electrosurgical generators at clinically used power outputs of 40 to 60 watts, and both high- and low-voltage (coagulation and cut) waveforms and commercially-available single-port devices. The effect on tissue was recorded by pictures and video camera and graded visually and histologically with hematoxylin and eosin stains. During activation of any standard monopolar laparoscopic instrument (scissors, coagulating electrode, etc), capacitive coupled currents resulting in visible tissue burn (blanching) caused by other adjacent cold instrument (graspers, etc) including metallic suction-irrigation cannulas and the laparoscope itself were noted. Histopathologic study confirmed transmural thermal damage extending to the mucosa of small bowel, even in the presence of mild serosa blanching. With prolonged activation of the electrosurgical generator, the capacitive coupled corona discharge burned the insulation and caused rapid insulation breakdown of the electrode instrument resulting in direct coupling (sparking, arcing) to adjacent cold instruments and more severe burning to the contacted tissue/organ.nnnCONCLUSIONSnDuring single-port laparoscopy and use of monopolar radiofrequency, the proximity and crossing of multiple instruments generate capacitive or direct coupled currents, which may cause visceral burns.

Identification of the TP53-induced glycolysis and apoptosis regulator in various stages of colorectal cancer patients

The TP53-induced glycolysis and apoptosis regulator (TIGAR) is a p53 target gene known to regulate glycolysis by acting as fructose bis-phosphatase (FBPase) and modulate reactive oxygen species. TIGAR expression has been implicated in oncogenesis and progression of several human cancers. However, TIGAR expression is not known in various stages of colorectal cancer (CRC). There is an increase in the colorectal cancer incidence in Saudi Arabia. We sought to analyze TIGAR expression in this ethnic group. The aim of this study was to investigate the TIGAR expression in colorectal cancer (CRC) patients from Saudi Arabia. Tissue microarray (TMA) was constructed from 22 matched colorectal tumor tissues and adjacent normal tissues. TIGAR expression was examined in TMA slide using immunohistochemistry. TIGAR mRNA was determined in 14 matched tumor tissue and adjacent normal tissue. TIGAR protein expression was also examined in CRC tumor tissues and cell lines. Statistical analyses (t-test) were applied to evaluate the significance of TIGAR expression. TIGAR mRNA level was upregulated significantly in stage II (p<0.01) and stage III (p<0.05) when compared to adjacent normal tissue. Immunohistochemical studies revealed that TIGAR expression was increased in colorectal cancer. Strong TIGAR positive staining was found in 68% (15/22) of the tumor samples with nuclear localization. TIGAR staining was found to be significantly increased in early stage (stage I and II) CRC (p<0.05) and late stage (stage III and IV) CRC (p<0.01). TIGAR protein was also found to be highly expressed in stage II and III colorectal cancer tissues and CRC cell lines. These findings indicate that TIGAR is highly expressed at the mRNA and protein levels in colorectal cancer with prominent nuclear localization. TIGAR expression may be used as a bio-marker for detection of colorectal cancer and can be used as a target for developing therapeutics for the treatment of colorectal cancer.

Trends in colon cancer surgery in Ontario: 2002–2009

Aimu2002 The safety and efficacy of laparoscopic surgery for colon cancer is well established but its uptake in the province has not been previously explored. We report an investigation of the trends of open and laparoscopic surgery for colon cancer in Ontario, Canada.

Polymorphisms of tumor necrosis factor alpha in Middle Eastern population with colorectal cancer

Tumor necrosis factor-alpha (TNF-α) contributes in inflammation and has been implicated in the development of colorectal cancer (CRC). Single nucleotide polymorphisms (SNPs) in TNF-α promoter could affect the risk of CRC by regulating TNF-α production. This is the first study to investigate TNF-α SNPs in a Middle Eastern population. In this study, we examined three SNPs in TNF-α for association with CRC. One hundred CRC patients and 100 controls were genotyped for TNF-α -308, -238, and -857 using TaqMan allelic discrimination assay. The TNF-α -238 (G/A) genotype was significantly associated with high risk of CRC (pu2009=u20090.003552). The distribution of three genotypes of -238 G/A was significantly different between the controls and CRC patients even after Bonferroni’s correction. The AA genotype of -238 G/A SNP was observed at considerably higher proportion (13xa0%) in CRCs compared to controls (1xa0%). Additionally, similar to genotypes, the allelic frequencies of -238 G/A were significantly different between the CRC cases and controls (odds ratios (OR)u2009=u20097.647, χ2u2009=u200918.50, pu2009=u20090.00002). The genotype frequencies of -308 and -857 were not notably different between the cases and controls. TNF-α -238A may be useful as a screening marker to identify individuals prior to their acquiring CRC in the Saudi population although, further validations in larger cohorts are needed.

Association between perioperative beta blocker use and cancer survival following surgical resection

BACKGROUNDnRecent studies have demonstrated an association between beta-blocker exposure and improved survival in multiple cancer types. We sought to investigate the effects of beta-blockers at the time of index surgery for breast, lung, and colorectal cancer.nnnMATERIALS AND METHODSnUsing linked data from a provincial cancer registry, we conducted a retrospective matched cohort study comparing disease-specific and overall survival between patients over age 64 exposed and not exposed to beta-blockers before and after index surgical resection for breast, lung and colorectal cancer between April 1st, 2002 and December 31st, 2010. A high-dimensional propensity score was used to match patients and Cox proportional hazard models were used to estimate relative risks of the outcomes.nnnRESULTSn30,020 patients were included in the final matched cohorts. Mean follow up time for breast, lung, and colorectal cancer was 57.6xa0±xa030.5, 43.1xa0±xa028.7, and 53.4xa0±xa031.0 months, respectively. Thexa0adjusted hazard ratio for disease-specific mortality for patients exposed to beta-blockers was 1.03 (0.83-1.29) for breast, 1.05 (0.92-1.20) for lung, and 1.10 (0.96-1.25) for the colorectal cancer cohort.nnnCONCLUSIONSnIn this large population-based study, no association between perioperative beta-blocker exposure and improved cancer-specific survival for breast, lung, or colorectal cancer was demonstrated.

Laparoscopic Colorectal Surgery in the Emergency Setting: Trends in the Province of Ontario.

Background: The purpose of this study was to examine the adoption trends of emergency laparoscopic colorectal surgery in the province of Ontario. Study Design: We conducted a retrospective time-series analysis examining rates of emergency colorectal surgery among 10.5 million adults in Ontario, Canada from April 1, 2002 to December 31, 2009. We linked administrative claims databases and the Ontario Cancer Registry to assess procedure rates over time. Procedure trends were assessed using time-series analysis. Results: Over the 8-year period, 29,676 emergency colorectal procedures were identified. A total of 2582 (8.7%) were performed laparoscopically and 27,094 (91.3%) were open. Open and laparoscopic patients were similar with respect age, sex, and Charlson Comorbidity Index. The proportion of surgery for benign (63.8% of open cases vs. 65.6% laparoscopic, standardized difference=0.04) and malignant disease (36.2% open vs. 34.4% laparoscopic, standardized difference=0.04) was equal between groups. The percentage of emergency colorectal surgery performed laparoscopically increased from 5.7% in 2002 to 12.0% in 2009 (P<0.01). The use of laparoscopy increased for both benign and malignant disease. Statistically significant upward trends in laparoscopic surgery were seen for inflammatory bowel disease (P<0.01), obstruction (P<0.01), and colon cancer (P<0.01). From 2002 to 2009, annual procedure rates increased at a greater rate in nonacademic centers (P<0.01). Conclusions: Laparoscopic emergency colorectal surgery has increased significantly between 2002 and 2009 for both benign and malignant disease and for a wide range of diagnoses. This was driven in part by steadily rising usage of laparoscopy in nonacademic centers.

Lymphangioma of the ileocecal valve clinically masquerading as a submucosal small intestinal GIST: Report of a case and literature review

Lymphangiomas are rare tumors affecting the gastrointestinal tract, and may be seen in the bowel, gall bladder, and pancreas. They resemble hemangiomas, but consist of spaces of variable sizes containing lymph. In this report, we describe the case of a 53-year-old male who presented with abdominal pain and constipation. Computerized tomography (CT) scan showed a polypoidal lesion at the ileocecal valve which was thought to be a gastrointestinal stromal tumor. Resected specimen did, however, show a lymphangioma. We also describe the clinicopathologic features of gastrointestinal lymphangiomas with a literature review.