Centre for Academic Surgery - Molecular Oncology
The main focus of our work is surgical and molecular oncology, with particular emphasis on translational research. We are investigating colorectal cancer development and metastasis, and the molecular and clinical differences between microsatellite unstable (MSI), chromosome unstable (CIN) and microsatellite and chromosome stable (MACS) tumours. Another interest concerns the transfer of molecular technology into practical, clinical use: by including molecular parameters into clinical tumour staging and defining molecular risk patterns in large series of patients with different cancer types, we seek to improve the prognostic quality of tumour staging, predict combinations of risk factors that indicate certain predictive qualities and find subgroups of patients that are ultimately candidates for new molecular therapeutic strategies.
1. Prognostic markers: Development of a tumour atlas in colorectal cancer
Aim: to generate clinically relevant RNA signatures from microdissected tumours for outcome and treatment evaluation in colorectal cancer.
The development of molecular analytical techniques and their application to clinical diagnostic studies has been rapid. However, the reliable interpretation of results obtained from gene expression analyses is largely influenced by the selection of appropriate study material. Colorectal cancer biopsies contain multiple cell types, are multiclonal and are characterised by distinctive histopathologies with discrete gene expression profiles. As a result, gene expression profiles from bulk biopsies obscure clinically relevant expression signatures from areas associated with poor treatment outcome, such as those characterised by vascular and lymphatic invasion and lymphocytic infiltration. A critical consequence of this heterogeneity is that such samples are unable to provide robust expression signatures capable of accurate prognostic stratification of individual colorectal cancer patients following surgery. Our solution is to use microdissection to establish gene expression profiles from specific histopathological areas that are clinically relevant and associated with poor outcome. This will allow the development of a tumour atlas associating defined histopathological areas with specific gene expression profiles and treatment outcome.
Scientific relevance: This study represents a systematic and novel approach to identifying RNA signatures that are more appropriate for predicting disease outcome than those obtained from bulk biopsies. They should define distinct gene expression features associated with high metastatic potential and poor treatment outcome in primary colorectal cancers.
2. Molecular mechanisms: Identification of Vitamin D receptor-mediated signalling pathways involved in colorectal tumourigenesis
Aim: to identify the molecular mechanisms underlying the tumour-preventative effects of vitamin D.
Vitamin D, whose biological effects are mediated by the vitamin D receptor (VDR) has been postulated to play a role in CRC prevention. Its function has been linked to the inhibition of cancer cell growth and stimulation of cellular differentiation. Therefore, the VDR is viewed as an important target for cancer prevention and therapy by specific VDR modulators. We have discovered a molecular mechanism that accounts for the dysregulation of the vitamin D signalling pathway in colorectal cancers. Moreover, we have identified numerous vitamin D-dependent genes whose expression is co-regulated with VDR in normal colon, but becomes dysregulated in colorectal cancers. Some of these genes have previously been identified as vitamin D-responsive, but the majority have never been linked to vitamin D. A significant number of these novel vitamin D-regulated genes are negative regulators of the wnt pathway and positive regulators of the TGFβ pathway, the two prime signalling pathways implicated in colorectal cancer development.
Scientific relevance: The elucidation of the mechanisms by which vitamin D modifies the occurrence or progression of colorectal cancer is of prime relevance for the design of chemopreventative protocols for colorectal cancer. Our research is identifying vitamin D as a central coordinator of pathways that are critical for maintaining homeostasis in the normal colon.
3. PCR and clinical diagnostics
Molecular diagnostics offers the promise of accurately matching patient with treatment, and a resultant significant effect on improved disease outcome. More specifically, the real-time reverse transcription polymerase chain reaction (qRT-PCR), with its combination of conceptual simplicity and technical utility, has the potential to become a valuable analytical tool for the detection of mRNA targets from tissue biopsies and body fluids. Its potential is particularly promising in cancer patients, both as a prognostic assay and for monitoring response to therapy. Colorectal cancer provides an instructive paradigm for this potential as well as the problems associated with its use as a clinical assay.
Currently, histopathological staging, which provides a static description of the anatomical extent of tumour spread within a surgical specimen, defines patient prognosis. The detection of lymph node (LN) metastasis constitutes the most important prognostic factor in colorectal cancer and as the primary indicator of systemic disease spread, LN status determines the choice of postoperative adjuvant chemotherapy. However, its limitations are emphasised by the considerable prognostic heterogeneity of patients within a given tumour stage: not all patients with LN-negative cancers are cured and not all patients with LN-positive tumours die from their disease. This has resulted in a search for more accurate staging protocols and has seen the introduction of the concept of “molecular staging”, the incorporation of molecular parameters into clinical tumour staging. Quantification of disease-associated mRNA is one such parameter that utilises the qRT-PCR assay’s potential for generating quantitative results. These are not only more informative than qualitative data, but contribute to assay standardisation and quality management. However, there are many contradictory results encountered in the literature and there is an urgent need for standardisation at every level, starting with pre-assay sample acquisition and template preparation, assay protocols and post-assay analysis.
| 
