Seeing into cells

Medicine is undergoing a revolution. Disease is increasingly being redefined in terms of underlying molecular abnormalities, as opposed to the signs and symptoms of the patient. This new definition is referred to as the ‘molecular signature’ of a disease and the current developments in biomedical research are accordingly termed ‘molecular medicine’. In the case of cancer, we know that tumours result from genetic alterations of cells, which may involve overexpression or underexpression of normal genes, or mutations that generate abnormal gene products. This may affect any of the molecules within the cell, the cell membrane or the cancer-cell milieu. In addition, the microenvironment of a tumour, including stromal and vascular endothelial cells, is important for the growth and persistence of the tumour. This entire constellation of the abnormal molecular biology of tumour cells and their microenvironment is the molecular signature of cancer (Hanahan & Weinberg, 2000).