The recently discovered enzyme phosphatidylinositol 3-kinase (Pl 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, Pl(3)P, phosphatidylinositol 3,4-bisphosphate, Pl(3,4)P2, and phosphatidylinositol 3,4,5-trisphosphate, Pl(3,4,5)P3. Mutational studies of growth factor receptors and oncogenes have shown that the associated Pl 3-kinase and its products Pl(3,4)P2 and Pl(3,4,5)P3 regulate cell growth and transformation. The 3-PPI are not physiological substrates for the Pl-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 Pl(3,4)P2 and Pl(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 spectrometric 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 Pl(3,4,5)P3, and the product will be fully characterized by analytical, physicochemical and spectrometric measurements. In Phase 1I, these approaches will be adapted and extended for the syntheses of Pl(3)P, P13,4)P2, isomers and analogues.Awardee's statement of the potential commercial applications of the research: The precise roles and the mechanistic basis of action of the 3-PPI have not been defined, but the available evidence strongly suggests that these novel polyphosphoinositides play a critical role in transmitting growth signals to the cell. The 3-PPI and analogues also have commercial potential in the development of anticancer agents and medical biotechnology.National Institute of General Medical Sciences (NIGMS)
