Royal Brisbane and Womens Hospital Research Foundation

Brisbane, Australia

Royal Brisbane and Womens Hospital Research Foundation

Brisbane, Australia
Time filter
Source Type

Ishii T.,Royal Brisbane and Womens Hospital Research Foundation | Ishii T.,Queensland Institute of Medical Research | Ishii T.,Okayama University | Notohara K.,Kurashiki Central Hospital | And 16 more authors.
American Journal of Surgical Pathology | Year: 2011

Advanced colorectal polyps are identified based on size ≥10 mm, high-grade dysplasia, and/or villous histology. A diagnosis of tubular adenoma (TA) is recommended if villous change occupies <20% of the lesion, or tubulovillous adenoma (TVA) is recommended if there is 20% to 80% villosity. We hypothesized that even subtle villous changes (1% to 20%) would correlate with advanced molecular features. Two hundred sixty-nine colorectal adenomas were examined for KRAS and BRAF mutation and immunohistochemical staining of β-catenin, O6-Methyl Guanine DNA Methyltransferase (MGMT), and p53. Adenomas were classified as TA1 (0% villosity, n=70), TA2 (1% to 20% villosity, n=81), or TVA (21% to 80% villosity, n=118). Clinical and molecular features were analyzed by univariate χ and multivariate logistic regression. There was an incremental increase in KRAS mutation frequency with increasing villous compartment (17.9% TA1, 59.0% TA2, 78.4% TVA; P<0.001). MGMT was more frequently lost in TA2 (37.0%) than in TA1 (8.6%) (P<0.001) but did not differ from TVA (39.8%). p53 overexpression was more common in TA2 (38.3%) than in TA1 (10.0%) (P<0.001) but did not differ from TVA (32.2%). On multivariate analysis, TA2 adenomas were more likely to have a KRAS mutation [odds ratio (OR) 6.6, 95% confidence interval (CI), 3.0-14.2], MGMT loss (OR 6.2, 95% CI, 2.4-16.0), or p53 overexpression (OR 5.6, 95% CI, 2.3-13.7) than TA1. We have identified a subgroup of TAs based on subtle villous changes. These adenomas are more likely to show molecular features that are characteristic of TVAs than TAs. These data support the concept that any villous change may indicate increased malignant potential and may be useful to consider when assigning surveillance guidelines. Copyright © 2011 by Lippincott Williams & Wilkins.

De Carcer D.A.,CSIRO | Cuiv P.O.,CSIRO | Wang T.,CSIRO | Wang T.,Shanghai JiaoTong University | And 8 more authors.
ISME Journal | Year: 2011

We applied constrained ordination numerical ecology methods to data produced with a human intestinal tract-specific phylogenetic microarray (the Aus-HIT Chip) to examine the microbial diversity associated with matched biopsy tissue samples taken from the caecum, transverse colon, sigmoid colon and rectum of 10 healthy patients. Consistent with previous studies, the profiles revealed a marked intersubject variability; however, the numerical ecology methods of analysis allowed the subtraction of the subject effect from the data and revealed, for the first time, evidence of a longitudinal gradient for specific microbes along the colorectum. In particular, probes targeting Streptococcus and Enterococcus spp. produced strongest signals with caecal and transverse colon samples, with a gradual decline through to the rectum. Conversely, the analyses suggest that several members of the Enterobacteriaceae increase in relative abundance towards the rectum. These collective differences were substantiated by the multivariate analysis of quantitative PCR data. We were also able to identify differences in the microarray profiles, especially for the streptococci and Faecalibacterium prausnitzii, on the basis of gender. The results derived by these multivariate analyses are biologically intuitive and suggest that the biogeography of the colonic mucosa can be monitored for changes through cross-sectional and/or inception cohort studies. © 2011 International Society for Microbial Ecology All rights reserved.

Whitehall V.L.J.,Royal Brisbane and Womens Hospital Research Foundation | Whitehall V.L.J.,Queensland Health | Rickman C.,Royal Brisbane and Womens Hospital Research Foundation | Bond C.E.,Royal Brisbane and Womens Hospital Research Foundation | And 19 more authors.
International Journal of Cancer | Year: 2012

Oncogenic PIK3CA mutations contribute to colorectal tumorigenesis by activating AKT signaling to decrease apoptosis and increase tumor invasion. A synergistic association of PIK3CA mutation with KRAS mutation has been suggested to increase AKT signaling and resistance to antiepidermal growth factor receptor inhibitor therapy for advanced colorectal cancer, although studies have been conflicting. We sought to clarify this by examining PIK3CA mutation frequency in relation to other key molecular features of defined pathways of tumorigenesis. PIK3CA mutation was assessed by high resolution melt analysis in 829 colorectal cancer samples and 426 colorectal polyps. Mutations were independently correlated with clinicopathological features including patient age, sex and tumor location as well as molecular features including microsatellite instability, KRAS and BRAF mutation, MGMT methylation and the CpG Island Methylator Phenotype (CIMP). Mutation of the helical (Exon 9) and catalytic (Exon 20) domain mutation hotspots were also examined independently. Overall, PIK3CA mutation was positively correlated with KRAS mutation (p < 0.001), MGMT methylation (p = 0.007) and CIMP (p < 0.001). Novel, exon-specific associations linked Exon 9 mutations to a subgroup of cancers characterized by KRAS mutation, MGMT methylation and CIMP-Low, whilst Exon 20 mutations were more closely linked to features of serrated pathway tumors including BRAF mutation, microsatellite instability and CIMP-High or Low. PIK3CA mutations were uncommonly, but exclusively, seen in tubulovillous adenomas (4/124, 3.2%) and 1/4 (25.0%) tubulovillous adenomas with a focus of cancer. These data provide insight into the molecular events driving traditional versus serrated pathway tumorigenesis. Copyright © 2011 UICC.

Bond C.E.,Royal Brisbane and Womens Hospital Research Foundation | Umapathy A.,Royal Brisbane and Womens Hospital Research Foundation | Ramsnes I.,Royal Brisbane and Womens Hospital Research Foundation | Greco S.A.,Royal Brisbane and Womens Hospital Research Foundation | And 9 more authors.
International Journal of Cancer | Year: 2012

The majority of "serrated pathway" colorectal cancers have mutation of the BRAF oncogene and display the CpG island methylator phenotype (CIMP). Half these cancers have microsatellite instability (MSI) and an excellent prognosis. In the absence of MSI (microsatellite stable, MSS), BRAF mutation has been associated with a particularly poor prognosis. "Traditional pathway" cancers are BRAF wild type. Mutation of p53 is common and this correlates with advanced stage. We therefore hypothesized that p53 mutation would be common in MSS/BRAF mutant colorectal cancer. One thousand and eighty-one colorectal cancers were screened for BRAF mutation to identify two BRAF mutant study groups (MSI: n = 77; MSS: n = 69) and a BRAF wild type control group (n = 101). These were screened for p53 mutation by high resolution melt analysis and classified for CIMP and MGMT methylation by quantitative methylation specific PCR. Molecular data were compared to patient age, gender, tumor location and stage. p53 was mutated significantly more frequently in MSS/BRAF mutant (28/69, 40.6%) compared to MSI/BRAF mutant cancers (13/77, 16.9%), but this mutation rate did not differ from MSS/BRAF wild type cancers (47/101, 46.5%)(p < 0.0001). CIMP was less common in MSS/BRAF mutant (26/47, 55.3%) compared to MSI/BRAF mutant cancers (41/54, 75.9%), but was more common than in MSS/BRAF wild type cancers (3/85, 3.5%) (p < 0.0001). MSS/BRAF mutant cancers were more commonly proximal (38/54, 70.3%), but were similar to MSS/BRAF wild type cancers in terms of patient age, gender distribution and stage at presentation. MSS/BRAF mutant cancers share molecular and clinical features of both the serrated and traditional pathways of colorectal tumorigenesis. Copyright © 2011 UICC.

Leggett B.,Royal Brisbane and Womens Hospital Research Foundation | Leggett B.,Royal Brisbane and Womens Hospital | Whitehall V.,Royal Brisbane and Womens Hospital Research Foundation | Whitehall V.,Queensland Health
Gastroenterology | Year: 2010

The "serrated neoplastic pathway" describes the progression of serrated polyps, including sessile serrated adenomas and traditional serrated adenomas, to colorectal cancer. The recognition of this pathway during the last 15 years has led to a paradigm shift in our understanding of the molecular basis of colorectal cancer and significant changes in clinical practice. These findings are particularly relevant to prevention of interval cancers through colonoscopy surveillance programs-an important issue for colonoscopists. In the past, all serrated polyps were classified simply as hyperplastic polyps and were considered to have no malignant potential. Reappraisal of this view was largely driven by increasing recognition of the malignant potential of hyperplastic polyposis. © 2010 AGA Institute.

Dowty J.G.,University of Melbourne | Win A.K.,University of Melbourne | Buchanan D.D.,Queensland Institute of Medical Research | Lindor N.M.,Mayo Medical School | And 24 more authors.
Human Mutation | Year: 2013

We studied 17,576 members of 166 MLH1 and 224 MSH2 mutation-carrying families from the Colon Cancer Family Registry. Average cumulative risks of colorectal cancer (CRC), endometrial cancer (EC), and other cancers for carriers were estimated using modified segregation analysis conditioned on ascertainment criteria. Heterogeneity in risks was investigated using a polygenic risk modifier. Average CRC cumulative risks at the age of 70 years (95% confidence intervals) for MLH1 and MSH2 mutation carriers, respectively, were estimated to be 34% (25%-50%) and 47% (36%-60%) for male carriers and 36% (25%-51%) and 37% (27%-50%) for female carriers. Corresponding EC risks were 18% (9.1%-34%) and 30% (18%-45%). A high level of CRC risk heterogeneity was observed (P < 0.001), with cumulative risks at the age of 70 years estimated to follow U-shaped distributions. For example, 17% of male MSH2 mutation carriers have estimated lifetime risks of 0%-10% and 18% have risks of 90%-100%. Therefore, average risks are similar for the two genes but there is so much individual variation about the average that large proportions of carriers have either very low or very high lifetime cancer risks. Our estimates of CRC and EC cumulative risks for MLH1 and MSH2 mutation carriers are the most precise currently available. © 2012 Wiley Periodicals, Inc.

Worthley D.L.,Royal Brisbane and Womens Hospital Research Foundation | Worthley D.L.,Queensland Institute of Medical Research | Whitehall V.L.J.,Royal Brisbane and Womens Hospital Research Foundation | Whitehall V.L.J.,Queensland Institute of Medical Research | And 16 more authors.
Digestive Diseases and Sciences | Year: 2011

Background: DNA methylation varies throughout the normal colorectal mucosa and DNA methylation in normal appearing mucosa is associated with serrated and adenomatous neoplasia elsewhere within the colorectum. Aims: The purpose of this study was to measure luminal chemistry, rectal proliferation and mucosal DNA methylation and thus determine whether regional and pathological patterns of DNA methylation could be explained by luminal and epithelial factors. Methods: Twenty healthy subjects had normal rectal mucosal biopsies and a 24-h fecal collection. Rectal biopsies were analyzed for epithelial proliferation (Ki67 immunohistochemistry) and DNA methylation at 17 different markers, including "type A" markers (ESR1, GATA5, HIC1, HPP1, SFRP1), "type C" markers (MGMT, MLH1, CDKN2A, MINT1, MINT2, MINT31, IGF2, CACNA1G, NEUROG1, SOCS1, RUNX3), and LINE-1. Fecal analysis included short-chain fatty acids (SCFA), pH and ammonia. Mean "type A" and CIMP panel methylation Z-scores were calculated. Results: Rectal proliferation was significantly correlated with methylation at ESR1 (ρ = 0.81, P = 0.003) and GATA5 (ρ = 0.78, P = 0.012). LINE-1 methylation was 71.7 vs. 74.1%, in patients with "low" and "high" fecal total SCFA concentration (defined by the median value), respectively (P = 0.0019). On multivariate linear regression "type A" methylation was independently associated with rectal proliferation (P = 0.001). LINE-1 methylation was directly associated with rectal proliferation (P = 0.038) and total fecal SCFA concentration (P = 0.002), and inversely associated with fecal NH3 concentrations (P = 0.003). Conclusions: DNA methylation in normal rectal mucosa is associated with crypt proliferation and fecal SCFA concentration. These associations may help to explain regional differences in DNA methylation as well as providing a possible link between the colorectal lumen and carcinogenesis. © 2010 Springer Science+Business Media, LLC.

Loading Royal Brisbane and Womens Hospital Research Foundation collaborators
Loading Royal Brisbane and Womens Hospital Research Foundation collaborators