D-3 Phosphorylated Phosphoinositides and Analogs

The recently discovered enzyme phosphatidylinositol 3-kinase (PI 3- kinase) physically associates with and is phosphorylated by activated growth factor receptors and oncogenes which manifest protein-tyrosine kinase activity. It phosphorylates phosphatidylinositols specifically at the D-3-hydroxyl to produce the 3-phosphorylated phosphoinositides, 3-PPI, comprising phosphatidylinositol 3-phosphate, PI(3)P, phosphatidylinositol 3,4-bisphosphate, PI(3,4)P2, and phosphatidylinositol 3,4,5-trisphosphate, PI(3,4,5)P3. Mutational studies of growth factor receptors and oncogenes have shown that the associated PI 3-kinase and its products PI(3,4)P2 and PI(3,4,5)P3 regulate cell growth and transformation. The 3-PPI are not physiological substrates for the PI-specific phospholipases C, and so the intact lipids have been suggested as novel critical second messengers of growth signals. Biochemical studies to determine the cellular targets of PI(3,4)P2 and PI(3,4,5)P3, the metabolic fate of these lipids, and their roles in the cell cycle have been handicapped because well characterized 3-PPI samples are not readily available; there is no commercial source. These materials are needed as research probes for defining their biochemical and physiological roles. The materials may also be useful for developing new anticancer agents and applications in medical biotechnology. Practical synthetic methods for 3-PPI are not available. The overall objectives are to develop synthetic methods and analogues for the 3-PPI and to prepare and characterize these by physicochemical and spectro- metric techniques. A strategy based on total synthesis and partial synthesis as complementary approaches is suggested. During Phase I, the feasibility of these complementary approaches will be tested for the synthesis of PI(3,4,5)P3, and the product will be fully characterized by analytical, physicochemical and spectrometric measurements. In Phase II, these approaches will be adapted and extended for the syntheses of PI(3)P, PI3,4)P2, isomers and analogues.