Apoptosis and inactivation of the PI3-kinase pathway by tetrocarcin A in breast cancers.
A survival kinase, Akt, is a downstream factor in the phosphatidylinositide-3'-kinase-dependent pathway, which mediates many biological responses including glucose uptake, protein synthesis and the regulation of proliferation and apoptosis, which is assumed to contribute to acquisition of malignant properties of human cancers. Here we find that an anti-tumor antibiotic, tetrocarcin A, directly induces apoptosis of human breast cancer cells. The apoptosis is accompanied by the activation of a proteolytic cascade of caspases including caspase-3 and -9, and concomitantly decreases phosphorylation of Akt, PDK1, and PTEN, a tumor suppressor that regulates the activity of Akt through the dephosphorylation of polyphosphoinositides. Tetrocarcin A affected neither expression of Akt, PDK1, or PTEN, nor did it affect the expression of Bcl family members including Bcl-2, Bcl-X(L), and Bax. These results suggest that tetrocarcin A could be a potent chemotherapeutic agent for human breast cancer targeting the phosphatidylinositide-3'-kinase/Akt signaling pathway.
Nakajima
Hiroo
H
Department of Endocrine and Breast Surgery, Kyoto Prefectural University of Medicine, Kawaramachi, Hirokoji, Kamikyo-ku, Kyoto 602-0841, Japan.
Sakaguchi
Koichi
K
Fujiwara
Ikuya
I
Mizuta
Mitsuhiko
M
Tsuruga
Mie
M
Magae
Junji
J
Mizuta
Naruhiko
N
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000617:Aminoglycosides / Q000494:pharmacology*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000617:Aminoglycosides; D000903:Antibiotics, Antineoplastic; D053148:Caspase 3; D053453:Caspase 9; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C494811:BCL2L1 protein, human; C025518:tetrocarcin A; C578562:PDPK1 protein, human