A chemical genetic screen identifies inhibitors of regulated nuclear export of a Forkhead transcription factor in PTEN-deficient tumor cells

Kau, Tweeny R; Schroeder, Frank C.; Ramaswamy, Shivapriya; Wojciechowski, Cheryl L; Zhao, Jean J.; Roberts, Thomas M.; Clardy, Jon; Sellers, William R.; Silver, Pamela A.

doi:10.1016/s1535-6108(03)00303-9

Cited by 325 publications

(285 citation statements)

References 55 publications

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“…Proteasome inhibitors MG132 and lactacystin were purchased from Sigma Chemical Co. (St Louis, MO) and were used at 5 (MG132) or 10 (lactacystin) mM for 12 h prior to cell harvesting. PI3-kinase inhibitor LY294002 (Sigma Chemical Co.) and Akt Inhibitor IV (compound 5233705, EMD Biosciences Inc., San Diego, CA) (Kau et al, 2003) were used at 4 and 50 mM concentrations, respectively, for 12 h prior to harvesting cells.…”

Section: Methodsmentioning

confidence: 99%

Complex regulation of human androgen receptor expression by Wnt signaling in prostate cancer cells

et al. 2006

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Section: Methodsmentioning

confidence: 99%

Complex regulation of human androgen receptor expression by Wnt signaling in prostate cancer cells

et al. 2006

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“…Western blot analysis of phospho-proteins demonstrated that EGFR inhibition selectively blocked phosphorylation of ERK1/2 and RPS6 in cells with wt-VHL. The inhibition of RPS6 phosphorylation by Iressa, however, was not universal, which may relate to the presence of a PTEN mutation in 786-O and its derivatives (Kau et al, 2003). Mutant VHL lines showed little response to Iressa in terms of ERK and RPS6 phosphorylation and AKT phosphorylation was unaffected by either agent irrespective of VHL.…”

Section: Discussionmentioning

confidence: 93%

Synergistic growth inhibition by Iressa and Rapamycin is modulated by VHL mutations in renal cell carcinoma

et al. 2005

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Epidermal growth factor receptor (EGFR) and tumour growth factor alpha (TGFa) are frequently overexpressed in renal cell carcinoma (RCC) yet responses to single-agent EGFR inhibitors are uncommon. Although von Hippel -Lindau (VHL) mutations are predominant, RCC also develops in individuals with tuberous sclerosis (TSC). Tuberous sclerosis mutations activate mammalian target of rapamycin (mTOR) and biochemically resemble VHL alterations. We found that RCC cell lines expressed EGFR mRNA in the near-absence of other ErbB family members. Combined EGFR and mTOR inhibition synergistically impaired growth in a VHLdependent manner. Iressa blocked ERK1/2 phosphorylation specifically in wt-VHL cells, whereas rapamycin inhibited phospho-RPS6 and 4E-BP1 irrespective of VHL. In contrast, phospho-AKT was resistant to these agents and MYC translation initiation (polysome binding) was similarly unaffected unless AKT was inhibited. Primary RCCs vs cell lines contained similar amounts of phospho-ERK1/2, much higher levels of ErbB-3, less phospho-AKT, and no evidence of phospho-RPS6, suggesting that mTOR activity was reduced. A subset of tumours and cell lines expressed elevated eIF4E in the absence of upstream activation. Despite similar amounts of EGFR mRNA, cell lines (vs tumours) overexpressed EGFR protein. In the paired cell lines, PRC3 and WT8, EGFR protein was elevated posttranscriptionally in the VHL mutant and EGF-stimulated phosphorylation was prolonged. We propose that combined EGFR and mTOR inhibitors may be useful in the subset of RCCs with wt-VHL. However, apparent differences between primary tumours and cell lines require further investigation.

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“…To investigate the role of Akt phosphorylation on PRAS40 activation, we administered Akt inhibitor IV (Calbiochem, San Diego, CA, USA), a cell-permeable benzimidazole compound that inhibits Akt phosphorylation by targeting the adenosine triphosphate binding site of a kinase upstream of Akt, but downstream of PI3K (Kau et al, 2003). Akt inhibitor IV was dissolved in DMSO PRAS40 protects motor neurons from death after SCI F Yu et al to make a stock solution of 10 mmol/L, and further diluted to 100 mmol/L in filtered PBS (pH 7.4) before use.…”

Section: Drug Injectionmentioning

confidence: 99%

Increased Expression of a Proline-Rich Akt Substrate (PRAS40) in Human Copper/Zinc-Superoxide Dismutase Transgenic Rats Protects Motor Neurons from Death after Spinal Cord Injury

Narasimhan

Saito

et al. 2007

J Cereb Blood Flow Metab

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The serine-threonine kinase, Akt, plays an important role in the cell survival signaling pathway. A proline-rich Akt substrate, PRAS40, has been characterized, and an increase in phospho-PRAS40 (pPRAS40) is neuroprotective after transient focal cerebral ischemia. However, the involvement of PRAS40 in the cell death/survival pathway after spinal cord injury (SCI) is unclear. Liposomemediated PRAS40 transfection was performed to study whether overexpression of pPRAS40 is neuroprotective. We further examined the expression of pPRAS40 after SCI by immunohistochemistry and Western blot using copper/zinc-superoxide dismutase (SOD1) transgenic (Tg) rats and wild-type (Wt) littermates. We then examined the relationship between PRAS40 and Akt by injection of LY294002, a phosphatidylinositol 3-kinase (PI3K) pathway inhibitor, or Akt inhibitor IV, a compound that inhibits Akt activation after SCI. Our data demonstrated that increased pPRAS40 resulted in survival of more motor neurons compared with control complementary DNA transfection. Phosphorylated PRAS40 increased in the Wt rats after SCI, whereas there was a greater and prolonged increase in the SOD1 Tg rats. Coimmunoprecipitation showed that binding of pPRAS40 with 14-3-3 increased 1 day after SCI in the Wt rats, whereas there was a significant increase in the Tg rats. The inhibitor studies showed that phospho-Akt and pPRAS40 were decreased after injection of LY294002 or Akt inhibitor IV. We conclude that an increase in pPRAS40 by transfection after SCI results in survival of motor neurons, and overexpression of SOD1 in the Tg rats results in an increase in endogenous pPRAS40 and a decrease in motor neuron death through the PI3K/Akt pathway.

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A chemical genetic screen identifies inhibitors of regulated nuclear export of a Forkhead transcription factor in PTEN-deficient tumor cells

Cited by 325 publications

References 55 publications

Complex regulation of human androgen receptor expression by Wnt signaling in prostate cancer cells

Complex regulation of human androgen receptor expression by Wnt signaling in prostate cancer cells

Synergistic growth inhibition by Iressa and Rapamycin is modulated by VHL mutations in renal cell carcinoma

Increased Expression of a Proline-Rich Akt Substrate (PRAS40) in Human Copper/Zinc-Superoxide Dismutase Transgenic Rats Protects Motor Neurons from Death after Spinal Cord Injury

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