Previous studies by the applicant indicated that BCR/ABL, a leukemogenic tyrosine kinase, activates phosphatidylinositol-3 kinase (PI-3K), which plays an essential role in BCR/ABL-induced leukemogenesis. The objective of the proposed research is to examine molecular interactions between BCR/ABL and PI-3K, to determine the crucial downstream effectors of PI-3K, and to investigate if simultaneous inhibition of BCR/ABL and PI-3K has synergistic anti-leukemia effect.
The first aim of this application is focused on examination of the mechanisms of BCR/ABL-PI-3K interactions. For this purpose various PI-3K mutants will be tested. Also, the intermediating proteins will be identified and their role in BCP/ABL-PI-3K interaction will be determined.
The second aim i s to investigate the mechanisms of activation of the downstream effectors of PI-3K in BCR/ABL-mediated transformation. The already known effectors such as Akt and Raf-1 will be assayed.
The third aim i s to examine the role of PI-3K and its downstream effectors in the malignant progression of CML from chronic phase to blast crisis. For this reason, a murine model will be employed consisting of the BCR/ABL-induced transformation of p53+/+ and P53-/- bone marrow cells.
The fourth aim i s to determine if simultaneous inhibition of BCR/ABL and PI-3K exerts synergistic antileukemia effect. Previous studies by the applicant revealed that downregulation of BCR/ABL expression by an antisense strategy or inhibition of PI-3K by its specific inhibitor wortmannin (WT), strongly inhibited proliferation of chronic myelogenous leukemia cells without affecting normal hematopoiesis. Preliminary data indicate that simultaneous inhibition of both BCR/ABL and PI-3K exerts synergistic antileukemia effect. The BCR/ABL antisense strategy and the ABL specific inhibitor will be employed to down modulate BCR/ABL, and PI-3K activity will be simultaneously inhibited by WT. Bone marrow purging experiments will be performed to test the antitumor effectiveness of the simultaneous inhibition of BCR/ABL and PI-3K in conditions mimicking those of bone marrow purging. Finally, the applicant will test the effects of a systemic therapy consisting of simultaneous inhibition of BCR/ABL and PI-3K using the applicant's in vivo models of CML in SCID mice.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA083700-02
Application #
6377544
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Program Officer
Forry, Suzanne L
Project Start
2000-07-01
Project End
2004-06-30
Budget Start
2001-07-01
Budget End
2002-06-30
Support Year
2
Fiscal Year
2001
Total Cost
$283,950
Indirect Cost
Name
Temple University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
City
Philadelphia
State
PA
Country
United States
Zip Code
19122
Ren, Shu-Yue; Bolton, Elisabeth; Mohi, M Golam et al. (2005) Phosphatidylinositol 3-kinase p85{alpha} subunit-dependent interaction with BCR/ABL-related fusion tyrosine kinases: molecular mechanisms and biological consequences. Mol Cell Biol 25:8001-8
Ren, Shu-yue; Xue, Fan; Feng, Jan et al. (2005) Intrinsic regulation of the interactions between the SH3 domain of p85 subunit of phosphatidylinositol-3 kinase and the protein network of BCR/ABL oncogenic tyrosine kinase. Exp Hematol 33:1222-8
Stoklosa, Tomasz; Slupianek, Artur; Datta, Mandrita et al. (2004) BCR/ABL recruits p53 tumor suppressor protein to induce drug resistance. Cell Cycle 3:1463-72
Slupianek, Artur; Skorski, Tomasz (2004) NPM/ALK downregulates p27Kip1 in a PI-3K-dependent manner. Exp Hematol 32:1265-71
Nieborowska-Skorska, Malgorzata; Hoser, Grazyna; Kossev, Plamen et al. (2002) Complementary functions of the antiapoptotic protein A1 and serine/threonine kinase pim-1 in the BCR/ABL-mediated leukemogenesis. Blood 99:4531-9
Slupianek, A; Schmutte, C; Tombline, G et al. (2001) BCR/ABL regulates mammalian RecA homologs, resulting in drug resistance. Mol Cell 8:795-806