Biological and clinical characterisation of human phosphatidylinositide 3-kinase mutations

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Colorectal and breast cancers are the two most common registrable cancers in Australia and are second only to lung cancer in the total number of cancer deaths each year (4,678 and 2,612 deaths in 1997 for colorectal and breast, respectively). Ovarian cancer kills a further 740 women each year (Source: Cancer in Australia 1997, AIHW and AACR 2000). Thus, on average, one Australian dies of colorectal, breast or ovarian cancer every hour! Clearly, these are major diseases with a significant impact on our society. Unfortunately, though, we still do not understand the basic molecular and-or biochemical abnormalities that initiate and-or drive the development of these cancers. Our laboratory has recently reported a high frequency of mutation of the phosphoinositide 3-kinase (PI3K) gene PIK3CA in breast, colorectal and ovarian tumours. This work, funded by the NHMRC, has not only confirmed that PI3K is a bone fide human oncogene but also that mutations in the PI3K family of genes are one of the most common, and thus potentially one of the most important, genetic abnormalities in solid human tumours. In the current proposal, we aim to extend and complement our genetic studies by addressing the biological consequences and clinical significance of the mutations we have identified. This will provide crucial new insights into the biology of human tumourigenesis and further our understanding of the critical pathways and processes involved in the initiation and progression of human tumours. Such knowledge will help us to identify novel markers for diagnosis, prognosis and the early detection of cancer and enable a rational approach to the design of new anti-cancer therapies.