title: Prolactin and heregulin override DNA damage-induced growth arrest and promote phosphatidylinositol-3 kinase-dependent proliferation in breast cancer cells.
abstract: Heregulin (HRG), a ligand of ErbB receptor tyrosine kinases, is a potent mitogenic factor for breast cancer cells. Prolactin (PRL) has also been reported to regulate proliferation in breast cancer cells through its receptor, a member of the type I cytokine receptor family. Cytokine receptors are potent mitogens in hematopoietic cells, where they also override DNA damage-induced growth arrest checkpoints through activation of a phosphatidylinositol-3 kinase (PI3K) signaling pathway. In this study, we assessed the effect of gamma-irradiation on the mitogenic activity of HRG and PRL in breast cancer cells. HRG and PRL enhanced the proliferation of non-irradiated breast cancer cell lines in association with their ability to activate PI3K signaling pathways. Both growth factors also overrode irradiation-induced growth arrest in T47D cells, which resulted in decreased viability after irradiation. An inhibitor of PI3K, LY294002, abrogated growth factor-induced proliferation and the activity of cell cycle-dependent kinases in non-irradiated and irradiated cells. Thus, growth factors acting through distinct receptor families share a similar PI3K-dependent ability to promote proliferation and override DNA damage-induced growth arrest in breast cancer cells. These observations also suggest that selective activation of PI3K-dependent signaling can enhance radiosensitivity in breast cancer cells.
authors.affiliation: Department of Pharmacology, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
authors.forename: Paula
authors.initials: P
authors.lastname: Chakravarti
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Henry
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Quelle
mesh_terms: D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D002867:Chromones / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D015972:Gene Expression Regulation, Neoplastic; D006133:Growth Substances; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D020890:Neuregulin-1 / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011388:Prolactin / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D002867:Chromones; D006133:Growth Substances; D009025:Morpholines; D020890:Neuregulin-1; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D011388:Prolactin; D004247:DNA; D019869:Phosphatidylinositol 3-Kinases