Simon Siu Man Ng

Promoter methylation of the Wnt/β‐catenin signaling antagonist Dkk‐3 is associated with poor survival in gastric cancer

Abnormal activation of the Wnt/β‐catenin signaling pathway is common and critical in the pathogenesis of digestive cancers. In this study, the authors investigated the promoter methylation of the dickkopf homolog 3 gene Dkk‐3 in these cancers and its prognostic significance in gastric cancer.

MicroRNA dysregulation in colorectal cancer: a clinical perspective

Recent researches have shed light on the biological importance of microRNAs (miRNAs) in colorectal cancer (CRC) genesis, progression and response to treatments. The potential utility of miRNAs in the preclinical stage have been explored and investigated. In this review, we explored the literature and reviewed the cutting edge progress in the discovery of noninvasive plasma and faecal miRNAs for CRC early diagnosis, as well as their measurability and predictability. We also discussed the utility of miRNAs as novel prognostic and predictive markers, and their association with CRC clinical phenotypes including recurrence, metastasis and therapeutic outcomes. Finally, we summarised miRNA-related single-nucleotide polymorphisms and their potential influence on sporadic CRC susceptibility and therapeutic response. In conclusion, the use of miRNAs as biomarker for CRC is still in its infancy and need further characterisation and evaluation.

Identification of microRNA-135b in Stool as a Potential Noninvasive Biomarker for Colorectal Cancer and Adenoma

Purpose: Detecting microRNA (miRNA) in stool is a novel approach for colorectal cancer (CRC) screening. This study aimed to identify stool-based miRNA as noninvasive biomarkers for detection of CRC and adenoma. Experimental Design: A miRNA expression array covering 667 human miRNAs was performed on five pairs of CRC and two pairs of advanced adenoma tissues. The most upregulated miRNAs were validated in 40 pairs of CRC tissues, 16 pairs of advanced adenoma tissues, and 424 stool samples, including 104 CRCs, 169 adenomas, 42 inflammatory bowel diseases (IBD), and 109 healthy controls. miRNA levels were followed-up after removal of lesions. Results: In an array analysis, miR-31 and miR-135b were the most upregulated miRNAs in CRC and advanced adenoma as compared with their adjacent normal tissues (>13-fold increase). In stool samples, level of miR-135b was significantly higher in subjects with CRC (P < 0.0001) or adenomas (P < 0.0001), but not in patients with IBD compared with controls. miR-135b showed a significant increasing trend across the adenoma to cancer sequence (P < 0.0001). Levels of miR-31 were not significantly different among groups. The sensitivity of stool mR-135b was 78% for CRC, 73% for advanced adenoma, and 65% for any adenoma, respectively, with a specificity of 68%. No significant difference in the miR-135b level was found between proximal and distal colorectal lesions. Stool miR-135b dropped significantly upon removal of CRC or advanced adenoma (P < 0.0001). Conclusion: Stool-based miR-135b can be used as a noninvasive biomarker for the detection of CRC and advanced adenoma. Clin Cancer Res; 20(11); 2994–3002. ©2014 AACR.

Epigenetic inactivation of T-box transcription factor 5 , a novel tumor suppressor gene, is associated with colon cancer

T-box transcription factor 5 (TBX5) is a member of a phylogenetically conserved family of genes involved in the regulation of developmental processes. The function of TBX5 in cancer development is largely unclear. We identified that TBX5 was preferentially methylated in cancer using methylation-sensitive arbitrarily primed PCR. We aim to clarify the epigenetic inactivation, biological function and clinical significance of TBX5 in colon cancer. Promoter methylation was evaluated by combined bisulfite restriction analysis and bisulfite genomic sequencing. Cell proliferation was examined by cell viability assay and colony formation assay, apoptosis by flow cytometry and cell migration by wound-healing assay. TBX5 target genes were identified by cDNA microarray analysis. Cox regression model and log-rank test were used to identify independent predictors of prognosis. TBX5 was silenced or downregulated in 88% (7/8) colon cancer cell lines, but was expressed in normal colon tissues. Loss of gene expression was associated with promoter methylation. The biological function of TBX5 in human colon cancer cells was examined. Re-expression of TBX5 in silenced colon cancer cell lines suppressed colony formation (P<0.001), proliferation (P<0.001), migration and induced apoptosis (P<0.01). Induction of apoptosis was mediated through cross-talk of extrinsic apoptosis pathway, apoptotic BCL2-associated X protein and Granzyme A signaling cascades. TBX5 suppressed tumor cell proliferation and metastasis through the upregulation of cyclin-dependent kinase inhibitor 2A, metastasis suppressor 1 and downregulation of synuclein gamma and metastasis-associated protein 1 family member 2. TBX5 methylation was detected in 68% (71/105) of primary colon tumors. Multivariate analysis showed that patients with TBX5 methylation had a significantly poor overall survival (P=0.0007). In conclusion, we identified a novel functional tumor suppressor gene TBX5 inactivated by promoter methylation in colon cancer. Detection of methylated TBX5 may serve as a potential biomarker for the prognosis of this malignancy.

Fecal Bacteria Act as Novel Biomarkers for Noninvasive Diagnosis of Colorectal Cancer

Purpose: Gut microbiota have been implicated in the development of colorectal cancer. We evaluated the utility of fecal bacterial marker candidates identified by our metagenome sequencing analysis for colorectal cancer diagnosis. Experimental Design: Subjects (total 439; 203 colorectal cancer and 236 healthy subjects) from two independent Asian cohorts were included. Probe-based duplex quantitative PCR (qPCR) assays were established for the quantification of bacterial marker candidates. Results: Candidates identified by metagenome sequencing, including Fusobacterium nucleatum (Fn), Bacteroides clarus (Bc), Roseburia intestinalis (Ri), Clostridium hathewayi (Ch), and one undefined species (labeled as m7), were examined in fecal samples of 203 colorectal cancer patients and 236 healthy controls by duplex-qPCR. Strong positive correlations were demonstrated between the quantification of each candidate by our qPCR assays and metagenomics approach (r = 0.801–0.934, all P < 0.0001). Fn was significantly more abundant in colorectal cancer than controls (P < 0.0001), with AUROC of 0.868 (P < 0.0001). At the best cut-off value maximizing sum of sensitivity and specificity, Fn discriminated colorectal cancer from controls with a sensitivity of 77.7%, and specificity of 79.5% in cohort I. A simple linear combination of four bacteria (Fn + Ch + m7-Bc) showed an improved diagnostic ability compared with Fn alone (AUROC = 0.886, P < 0.0001) in cohort I. These findings were further confirmed in an independent cohort II. In particular, improved diagnostic performances of Fn alone (sensitivity 92.8%, specificity 79.8%) and four bacteria (sensitivity 92.8%, specificity 81.5%) were achieved in combination with fecal immunochemical testing for the detection of colorectal cancer. Conclusions: Stool-based colorectal cancer–associated bacteria can serve as novel noninvasive diagnostic biomarkers for colorectal cancer. Clin Cancer Res; 23(8); 2061–70. ©2016 AACR.

A novel peptide specifically targeting the vasculature of orthotopic colorectal cancer for imaging detection and drug delivery

Colorectal cancer (CRC) is the third most common malignancy and the fourth most frequent cause of cancer deaths worldwide. Ligand-mediated diagnosis and targeted therapy would have vital clinical applications in cancer treatment. In this study, an orthotopic model of colorectal cancer was established in mice. In vivo phage library selection was then utilized to isolate peptides specifically recognizing the vasculature of colorectal cancer tissues. A phage (termed TCP-1 phage) was isolated by this manner and it homed to the colorectal cancer tissues by 11- to 94-fold more than other organs. Chemical synthetic peptide (CTPSPFSHC, termed TCP-1) displayed by TCP-1 phage inhibited the homing ability of the phage to the tumor mass when co-injected intravenously with the TCP-1 phage into mice with colon cancer. Meanwhile, immunostaining analysis indicated that TCP-1 phage and peptide localized in the vasculature of the colorectal cancer tissue, but not of normal tissues. Moreover, TCP-1 peptide bound to blood vessels of surgical tissue samples of human colorectal cancer. After intravenous injection of FITC-labeled TCP-1 into the tumor-bearing mice for 20h, there was a strong fluorescent signal in the tumors but not other tissues when observed under blue light. In addition, TCP-1 conjugated with a pro-apoptotic peptide specifically induced apoptosis of tumor-associated blood vessels in vivo. The data define a novel peptide TCP-1 as an effective agent for imaging detection and drug delivery for colorectal cancer.

Outcomes and Predictors of Mortality and Stoma Formation in Surgical Management of Colonoscopic Perforations: A Multicenter Review

OBJECTIVES To perform a retrospective review of all patients with colonoscopic perforations managed in hospitals within the Eastern New Territories region of Hong Kong and to determine the predictors of mortality and stoma formation in patients with colonoscopic perforations. DESIGN Retrospective computer-based review. SETTING Multicenter (1 university teaching hospital and 2 district hospitals). METHODS We reviewed the outcomes of patients with colonoscopic perforations surgically managed between January 1, 1998, and December 31, 2005. Predictors of mortality and stoma formation were identified with multivariable analysis. MAIN OUTCOME MEASURES Mortality and stoma rates and their predictors. RESULTS A total of 37,971 colonoscopies were performed during the study period, and 43 colonoscopic perforations were identified. The overall perforation rate was 0.113% and represented a decreasing trend. There was no significant difference in the perforation rate between gastroenterologists (0.148%) and surgeons (0.091%) (P = .15). Perforations that occurred during diagnostic colonoscopies were significantly larger than those that occurred during therapeutic colonoscopies (P = .04), and the patients presented earlier (P = .02). Surgical intervention was performed in 39 patients. The overall morbidity and mortality rate was 48.7% and 25.6%, respectively. The stoma rate was 38.5%. The predictors of stoma formation include moderate to severe peritoneal contamination and the presence of malignant colonic neoplasms (P = .01 and P = .008, respectively). The predictors of mortality include American Society of Anesthesiologists class 3 or higher and antiplatelet therapy (P = .009 and P = .001, respectively). CONCLUSIONS Colonoscopic perforations were in a decreasing trend. Patients with predictors of mortality should not be treated conservatively. Other options of large bowel investigations should be considered in high-risk patients when the potential diagnostic yield is low.

Quality of life after laparoscopic vs open sphincter-preserving resection for rectal cancer

AIM To compare quality of life (QoL) outcomes in Chinese patients after curative laparoscopic vs open surgery for rectal cancer. METHODS Eligible Chinese patients with rectal cancer undergoing curative laparoscopic or open sphincter-preserving resection between July 2006 and July 2008 were enrolled in this prospective study. The QoL outcomes were assessed longitudinally using the validated Chinese versions of the European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-CR38 questionnaires before surgery and at 4, 8, and 12 mo after surgery. The QoL scores at the different time points were compared between the laparoscopic and open groups. A higher score on a functional scale indicated better functioning, whereas a higher score on a symptom scale indicated a higher degree of symptoms. RESULTS Seventy-four patients (49 laparoscopic and 25 open) were enrolled. The two groups of patients were comparable in terms of sociodemographic data, types of surgery, tumor staging, and baseline mean QoL scores. There was no significant decrease from baseline in global QoL for the laparoscopic group at different time points, whereas the global QoL was worse compared to baseline beginning at 4 mo but returned to baseline by 12 mo for the open group (P = 0.019, Friedman test). Compared to the open group, the laparoscopic group had significantly better physical (89.9 ± 1.4 vs 79.2 ± 3.7, P = 0.016), role (85.0 ± 3.4 vs 63.3 ± 6.9, P = 0.005), and cognitive (73.5 ± 3.4 vs 50.7 ± 6.2, P = 0.002) functioning at 8 mo, fewer micturition problems at 4-8 mo (4 mo: 32.3 ± 4.7 vs 54.7 ± 7.1, P = 0.011; 8 mo: 22.8 ± 4.0 vs 40.7 ± 6.9, P = 0.020), and fewer male sexual problems from 8 mo onward (20.0 ± 8.5 vs 76.7 ± 14.5, P = 0.013). At 12 mo after surgery, no significant differences were observed in any functional or symptom scale between the two groups, with the exception of male sexual problems, which remained worse in the open group (29.2 ± 11.3 vs 80.0 ± 9.7, P = 0.026). CONCLUSION Laparoscopic sphincter-preserving resection for rectal cancer is associated with better preservation of QoL and fewer male sexual problems when compared with open surgery in Chinese patients. These findings, however, should be interpreted with caution because of the small sample size of the study.

microRNA-20a in human faeces as a non-invasive biomarker for colorectal cancer

Objective Detection of microRNA (miRNA) aberrations in human faeces is a new approach for colorectal cancer (CRC) screening. The aim of this study was to characterise miR-20a in faeces as a non-invasive biomarker for diagnosis of CRC. Results miR-20a expression was significantly higher in the 40 CRC tumours compared to their respective adjacent normal tissues (P = 0.0065). Levels of miR-20a were also significantly higher in faecal samples from CRC patients (P < 0.0001). The area under receiver operating characteristic (AUROC) curve for miR-20a was 0.73, with a sensitivity of 55% and specificity of 82% for CRC patients compared with controls. No significant difference in the level of miR-20a was found between patients with proximal, distal, and rectal cancer. The use of antibiotics did not influence faecal miR-20a levels. Patients and Methods miR-20a was selected from an expression microarray containing 667 miRNAs. Further verification of miR-20a was performed in 40 pairs of primary CRC tissues, as well as 595 faecal samples (198 CRCs, 199 adenomas, and 198 healthy controls) using TaqMan probe based quantitative Real-Time PCR (qRT-PCR). Conclusions Faecal-based miR-20a can be utilised as a potential non-invasive biomarker for CRC screening.

Current and future molecular diagnostics in colorectal cancer and colorectal adenoma

Colorectal cancer (CRC) is one of the most prevalent cancers in developed countries. On the other hand, CRC is also one of the most curable cancers if it is detected in early stages through regular colonoscopy or sigmoidoscopy. Since CRC develops slowly from precancerous lesions, early detection can reduce both the incidence and mortality of the disease. Fecal occult blood test is a widely used non-invasive screening tool for CRC. Although fecal occult blood test is simple and cost-effective in screening CRC, there is room for improvement in terms of the accuracy of the test. Genetic dysregulations have been found to play an important role in CRC development. With better understanding of the molecular basis of CRC, there is a growing expectation on the development of diagnostic tests based on more sensitive and specific molecular markers and those tests may provide a breakthrough to the limitations of current screening tests for CRC. In this review, the molecular basis of CRC development, the characteristics and applications of different non-invasive molecular biomarkers, as well as the technologies available for the detection were discussed. This review intended to provide a summary on the current and future molecular diagnostics in CRC and its pre-malignant state, colorectal adenoma.