Colorectal Cancer Cell Biology, Epigenetics, Methylation, Biomarker development, Clinical Trials.
The main emphasis of Germaine’s research over the last 11 years has been to study the role of the Wnt antagonists in the development of colorectal neoplasia. The work has analysed the expression of a number of Wnt-related genes in tumour and normal colon mucosa taken from patients with sporadic colorectal cancer and patients with the genetic form of the disease, familial adenomatous polyposis (FAP).
The Wnt antagonist sFRP1 is silenced at the early stages of colorectal tumourigenesis. Subsequent work has shown that other Wnt antagonists (sFRP2, sFRP4, sFRP5 and WIF1) are also silenced. Analysis of the mechanism for gene silencing has shown that the sFRP1 gene is hypermethylated in tumours compared with normal mucosa.
More recently the work has examined the role of the Wnt antagonists in colitis-associated colorectal tumourigenesis. Ulcerative colitis affects around 120,000 people in the UK. Patients with UC have an increased risk of developing colorectal cancer with an actuarial cumulative incidence by disease duration of 1.5% at 10 years, 7.7% at 20 years, 15.8% at 30 years, and 22.7% at 40 years. Cancer risk is also associated with extent of disease.
Guidelines suggest all patients with UC have an index colonoscopy approximately 10 years after the onset of colitic symptoms. Surveillance colonoscopies are subsequently conducted yearly, 3-yearly or 5-yearly dependent on all the variables. Despite the surveillance in high-risk patients, colonoscopy is not wholly effective in cancer prevention. There is a pressing clinical need for a supplementary test that would improve our ability to identify patients for surgery, prior to the onset of invasive cancer. In addition, more effective risk stratification would reduce surveillance frequency for a lower risk population.
We have demonstrated hypermethylation of the Wnt antagonists (sFRP1 and WIF-1) in UC-associated dysplasia and cancer. Methylation of these markers was also detected in macroscopically normal mucosa taken from patients with UC-associated neoplasia suggesting a field change. Data sFRP1 and WIF1 demonstrates hypermethylaion of one or more CpG sites occurs in 77% of colitis-associated cancer, 72% of colitis-associated dysplasia and 56% of non-neoplastic tissue from patients with colitis-associated cancer. None of controls (UC patients without neoplasia and disease <10years) was methylated at these 4 CpG sites. The data indicates a sensitivity of 76% and a specificity of 100% at detecting colitis-associated neoplasia (cancer and dysplasia). This work is continuing and a panel of predictive markers is being developed to improve sensitivity.
In addition to providing biomarkers of progression, this also raises the potential for using therapies directed against these events to delay or prevent tumour formation. The panel of predictive markers may provide useful surrogate markers of effect in future clinical trials of novel treatment agents. Currently samples from small phase II clinical trial are being tested. The trial assesses the effect of glucocorticoid steroids on methylation and expression of the Wnt antagonists in the UC population. Cell line data suggests that these steroids can reverse the expression of the antagonists and may have an effect on tumour prevention.
K. J. Leong, W. Wei, L. A. Tannahill, G. M. Caldwell, C. E. Jones, D. G. Morton, G. M. Matthews, S. P. Bach. Methylation profiling of rectal cancer identifies novel markers of early-stage disease. British Journal of Surgery 2011; 98: In Press
Caldwell GM, Jones CE, Ashley AM, Wei W, Hejmadi RK, Morton DG, Matthews GM. (2010) Wnt signalling in adenomas of familial adenomatous polyposis patients. Br J Cancer. 103:910-7. Epub 2010 Jul 13.
Caldwell GM, Jones CE, Warrack R, Soon Y, Morton DG, Matthews GM (2008) Reorganisation of the Wnt signalling pathway in colorectal tumourigenesis. Br J Cancer 98:1437-42.
Caldwell GM, Jones CE, Taniere P, Warrack R, Soon Y, Matthews GM, Morton DG. (2006) Wnt antagonist sFRP1 is downregulated in premalignant large bowel adenomas. Br J Cancer. 94: 922-7.
Caldwell GM, Jones C, Gensberg K, Jan S, Hardy RG, Byrd P, Chughtai S, Wallis Y, Matthews GM, Morton DG. (2004) The Wnt Antagonist sFRP1 in Colorectal Tumorigenesis. Cancer Res. 64: 883-888.
Wagner KJ, Cooper WN, Grundy RG, Caldwell G, Jones C, Wadey RB, Morton D, Schofield PN, Reik W, Latif F, Maher ER. (2002) Frequent RASSF1A tumour suppressor gene promoter methylation in Wilms' tumour and colorectal cancer. Oncogene. 21:7277-82.
Caldwell GM, Eddy RL, Day CD, Haley LH, Cooper PR, Sait SS, Hejtmancik F, Smith RJ, Morton CC, Higgins MJ, Shows TB. (2001) Mapping of genes and transcribed sequences in a gene rich 400-kb region on human chromosome 11p15.1-->p14. Cytogenet Cell Genet. 92:103-7.
Caldwell GM, Kakuk LE, Griesinger IB, Simpson SA, Nowak NJ, Small KW, Maumenee IH, Rosenfeld PJ, Sieving PA, Shows TB, Ayyagari R. (1999) Bestrophin gene mutations in patients with Best vitelliform macular dystrophy. Genomics. 58:98-101.