Tumour buds, discussed above, appear to have many features of CSC, and the possibility that a sub-population of tumour buds may represent malignant stem cells is an open question requiring further investigation [133]

Tumour buds, discussed above, appear to have many features of CSC, and the possibility that a sub-population of tumour buds may represent malignant stem cells is an open question requiring further investigation [133]. The presence of a sub-population of CD26+ CSC in primary CRC tumours was found to predict distant metastases on Rabbit polyclonal to ZNF783.ZNF783 may be involved in transcriptional regulation follow-up [239]. more reliable prognostic markers and novel targets for therapy. This review focuses on cell surface proteins that correlate with tumour progression, metastasis and patient outcome, and discusses some of the challenges in finding prognostic protein markers in CRC. Keywords:colorectal cancer, biomarkers, proteomics, prognostic == 1. Introduction == Colorectal cancer (CRC) is a cancer of epithelial origin, localized to the large intestine and rectum. It is one of the most common cancers and will occur at some stage in approximately 5% of the population of the western world. The conventional prognostic factors for patient survival are histologic tumour grade (differentiation) and tumour stage (TNM, tumors/nodes/metastases, stages IIV) [1,2], which is based on depth of Primaquine Diphosphate tumour invasion, involvement of regional lymph nodes and metastatic spread Primaquine Diphosphate to other organs [3]. If metastasis has occurred, patient 5-year survival after surgery falls dramatically from 90% to less than 10% [4]. It is therefore important to increase our understanding of the molecular changes leading to development, spread and metastasis of CRC and to identify potentially prognostic and predictive markers for the disease. Despite the discovery of a range of intra- and extra-cellular protein biomarkers for CRC and continuing efforts to discover potentially prognostic and predictive markers using various approaches [512], the translation of this increasing volume of differential proteomic data into patient care remains a major challenge. This is partly due to the heterogeneous nature of CRC [13, 14] and the complexity of processes involved in its development and spread, but also to challenges presented in detecting and characterising glycoproteins and low abundance proteins [15,16] in complex mixtures. In addition, validation of candidate proteins as prognostic markers is time-consuming and expensive, and recent critical reviews of differentially expressed proteins from comparative proteomic studies have suggested that some reported proteins may be associated with general cellular stress responses, rather than being disease-specific biomarkers [17,18]. The development Primaquine Diphosphate of a reliable assay for determining prognosis and guiding post-surgical therapy therefore remains elusive. The metastatic potential of CRC may be already encoded in the primary tumour [19], and molecular staging using a classifier based on 43 genes has identified patient prognosis more accurately than the traditional clinical Primaquine Diphosphate staging, particularly for intermediate stage II and III patients [20]. It may be possible to identify disease signatures based on protein expression profiles in primary CRC tissues that reflect potential for disease progression and metastasis, and subsequently use these signatures to predict patient recovery and survival after Primaquine Diphosphate surgical removal of the primary CRC tissue. With this goal in mind, we have developed a 122-antibody microarray (DotScan CRC microarray; Medsaic Pty Ltd, NSW, Australia) for immunophenotyping live cells from fresh disaggregated CRC tissues [21,22]. Microarrays prepared as 10 nl antibody dots on nitrocellulose-coated microscope slides (FAST; Grace Bio-labs, Bend, OR, USA) bind cells with corresponding surface molecules, producing a binding pattern that reflects the surface immunophenotype of the mixed cell population. Bound cells are then fixed to the microarray with formalin, and specific sub-populations are profiled by multiplexing with mixtures of soluble fluorescently-labelled antibodies. Hierarchical clustering of binding patterns for these sub-populations of cells yields patient clusters that may correlate with disease stage, tumour invasiveness, differentiation, drug susceptibility or patient outcome. This antibody-based multiple marker approach has already been validated for the classification of a range of common human leukaemias and lymphomas [23]. The evolution of CRC from an adenomatous polyp to metastatic disease is dependent not only on progressive accumulation of genetic and epigenetic abnormalities [24], but also on the complex interactions of different sub-populations of cells within the tumour microenvironment (cancer cells,.