Ras-mediated up-regulation of survivin expression in cytokine-dependent murine pro-B lymphocytic cells.
Survivin, a member of the inhibitor of apoptosis protein (IAP) family, has been widely studied because of its aberrant expression in human cancer. Survivin has multiple functions, including cell-cycle regulation at mitosis, inhibition of apoptosis and caspase-independent cytoprotection. Clinical studies have shown that survivin is associated with resistance to treatment and its expression is linked to poor prognosis. Recent studies indicated that Ras pathways up-regulate survivin expression in hematopoietic cells. Here we analyzed downstream pathways of Ras in interleukin-3 (IL-3)-dependent Baf-3 murine-derived pro-B lymphocytic cells that express constitutively active Ras mutants, using signaling pathway-specific inhibitors. Both mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3 kinase (PI3-K) pathways are involved in the induction of survivin. Downstream of PI3-K, the signaling pathway is composed of two kinases, Akt and mammalian target of rapamycin (mTOR) pathways. In the downstream targets of PI3-K, mTOR but not Akt is responsible for survivin expression. Using a counterflow centrifugal elutriator, we observed G2/M phase-dominant survivin expression in Baf-3 cells. Interestingly, constitutively active Ras mutants also induced survivin in a cell cycle-dependent manner. Reporter assays of the survivin gene promoter revealed a transcriptional regulatory cis-acting region that is responsible for Ras signaling, indicating that Ras increases the transcription of the survivin gene through specific enhancer elements. These data illustrate the pathways regulating survivin expression by Ras. Ras activates the MAPK, PI3-K and mTOR pathways, and these signals enhance survivin transcription. Our data will provide the new information about mechanisms of survivin expression by Ras-signalling pathways.
Shinjyo
Tetsuharu
T
Department of Endocrinology and Metabolism, University of the Ryukyus, School of Medicine, Okinawa, Japan. tshinjo@ryudai2nai.com
Kurosawa
Hidemitsu
H
Miyagi
Jun-ichi
J
Ohama
Kiyoto
K
Masuda
Masato
M
Nagasaki
Akitoshi
A
Matsui
Hirotaka
H
Inaba
Toshiya
T
Furukawa
Yusuke
Y
Takasu
Nobuyuki
N
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D002352:Carrier Proteins / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology; D002460:Cell Line / Q000187:drug effects / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D004742:Enhancer Elements, Genetic; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation; D011905:Genes, ras; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D007377:Interleukin-3 / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis* / Q000235:genetics; D009025:Morpholines / Q000494:pharmacology; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000502:physiology; D017354:Point Mutation; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D012097:Repressor Proteins; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D020123:Sirolimus / Q000494:pharmacology; D000077022:Survivin; D058570:TOR Serine-Threonine Kinases; D014162:Transfection
D002352:Carrier Proteins; D002867:Chromones; D005419:Flavonoids; D051034:Inhibitor of Apoptosis Proteins; D007377:Interleukin-3; D008869:Microtubule-Associated Proteins; D009025:Morpholines; D015689:Oncogene Protein p21(ras); D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017853:Phosphotransferases (Alcohol Group Acceptor); D051057:Proto-Oncogene Proteins c-akt; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D020123:Sirolimus; D000077022:Survivin; D058570:TOR Serine-Threonine Kinases; C117749:Birc5 protein, mouse; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C546842:MTOR protein, human; C546843:mTOR protein, mouse; C514862:Akt1 protein, mouse; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one