title: Activated EGFR promotes the survival of B-lineage acute leukemia in the absence of stromal cells.
abstract: B-lineage acute leukemia (B-ALL) cells often require stromal cell support for optimal proliferation and apoptotic resistance. In addition, stromal cell contact can promote resistance to chemotherapeutic agents. However, the precise biochemical pathways within the leukemic cell that are activated by the bone marrow microenvironment which result promotion of cell proliferation and apoptotic protection are not fully characterized. We have recently reported that simultaneous inhibition of the MEK and PI3K pathways or the MEK and mTOR pathways promote rapid apoptosis of the stromal cell dependent B-lineage ALL cell line BLIN-2 in the presence of stromal cell support. These data indicated that stromal cell induced apoptotic protection is mediated by PI3K/mTOR and MEK in a mechanism(s) that suggests cross-talk or points of convergence. The EGF receptor (EGFR) has been reported to activate both MEK and PI3K. We report herein that use of the EGFR inhibitor, AG1478, inhibits BLIN-2 survival in the presence of stromal cells. FACS analysis revealed that EGFR is expressed on the surface of BLIN-2 cells. The addition of EGF to BLIN-2 cultures in the absence of stromal cells prolongs BLIN-2 survival. Similarly, introduction of a constitutively active form of EGFR, v-ErbB, into BLIN-2 prolongs the survival of BLIN-2 cells in the absence of stromal cell support. These data provide evidence that stimulation of the EGFR pathway is one mechanism by which the bone marrow microenvironment may contribute to the growth and survival of B-cell acute leukemia.
authors.affiliation: Department of Microbiology and Immunology, The Brody School of Medicine at East Carolina University, Greenville, North Carolina 27834, USA.
authors.forename: Justin D
authors.initials: JD
authors.lastname: Spengeman
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Green
authors.forename: James A
authors.initials: JA
authors.lastname: McCubrey
authors.forename: Fred E
authors.initials: FE
authors.lastname: Bertrand
mesh_terms: D017304:Annexin A5 / Q000737:chemistry; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D001402:B-Lymphocytes / Q000378:metabolism*; D001853:Bone Marrow; D001854:Bone Marrow Cells / Q000378:metabolism; D002051:Burkitt Lymphoma / Q000378:metabolism; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002469:Cell Separation; D002470:Cell Survival; D002478:Cells, Cultured; D018920:Coculture Techniques; D066246:ErbB Receptors / Q000378:metabolism* / Q000502:physiology*; D005434:Flow Cytometry; D006801:Humans; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011799:Quinazolines; D012190:Retroviridae / Q000235:genetics; D017154:Stromal Cells / Q000166:cytology*; D013997:Time Factors; D014407:Tumor Cells, Cultured; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D017304:Annexin A5; D000970:Antineoplastic Agents; D011799:Quinazolines; D020032:Tyrphostins; C101044:RTKI cpd; D019869:Phosphatidylinositol 3-Kinases; D066246:ErbB Receptors; D020930:MAP Kinase Kinase Kinases