Polyamine depletion delays apoptosis of rat  intestinal epithelial cells

Ray, Ramesh M.; Viar, Mary Jane; Yuan, Qing; Johnson, Leonard R.

doi:10.1152/ajpcell.2000.278.3.c480

Cited by 68 publications

(92 citation statements)

References 60 publications

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“…We report that ODC inhibition by DFMO treatment rapidly induces NF-B activation. It has been recently shown that apoptosis induced by DNA damaging agents and tumor necrosis factor-␣ is delayed in polyamine-depleted cells (3). Taken together, these results implicate NF-B in the protective action of DFMO against apoptotic agents in IEC-6 cells.…”

Section: Discussionmentioning

confidence: 61%

Polyamine Depletion Induces Rapid NF-κB Activation in IEC-6 Cells

Pfeffer¹,

Yang²,

Murti³

et al. 2001

Journal of Biological Chemistry

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The proliferation of the rat intestinal mucosal IEC-6 cell line requires polyamines, whose synthesis is catalyzed by the enzyme ornithine decarboxylase (ODC). ODC inhibition leads to polyamine depletion, as well as inhibition of both cell proliferation and apoptosis by regulating gene expression. The NF-B transcription factor regulates genes involved in apoptotic, immune, and inflammatory responses. In the present study we tested the hypothesis that NF-B is activated following ODC inhibition. We found that the inhibition of ODC by ␣-difluoromethylornithine (DFMO) resulted in a ϳ50% decrease in intracellular putrescine levels within 1 h. NF-B is activated by DFMO through the degradation of the inhibitory protein IB␣ that sequesters NF-B in the cytoplasm. The DFMO-induced NF-B complexes contain the p65 and p50 members of the Rel protein family. DFMO-induced NF-B activation was accompanied by the translocation of p65 from the cytoplasm into the nucleus. DFMO selectively inhibited a gene reporter construct dependent on the B site present in the HLA-B7 gene. In contrast, DFMO had no effect on a gene reporter construct dependent on the B site present in the interleukin-8 gene. Thus, we report that ODC inhibition activates the NF-B transcription factor, which may mediate the altered physiological state of intestinal cells that occurs following polyamine depletion.

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Section: Discussionmentioning

confidence: 61%

Polyamine Depletion Induces Rapid NF-κB Activation in IEC-6 Cells

Pfeffer¹,

Yang²,

Murti³

et al. 2001

Journal of Biological Chemistry

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“…EGF activates MEK1, and we have shown that expression of CA-MEK1 restores migration in polyamine-depleted cells [Vaidya et al, 2005]. We have previously reported that maximal polyamine depletion occurs after 4 days of treatment with 5 mM DFMO [Ray et al, 2000]. Within 6 h of DFMO treatment putrescine was undetectable, spermidine was absent after 24 h, and 40% of spermine remained after 4 days.…”

Section: Discussionmentioning

confidence: 74%

“…Polyamines are essential for various cellular processes including proliferation, migration, and apoptosis both in animals and in in vitro cell culture models [Ray et al, 2000[Ray et al, , 2001[Ray et al, , 2002Bhattacharya et al, 2004]. Since migration is involved in mucosal restitution, and polyamine depletion inhibits it, it is important to understand the mechanism by which polyamines affect this process.…”

Section: Introductionmentioning

confidence: 99%

MEK/ERK regulates adherens junctions and migration through Rac1

Ray

Vaidya

Johnson

2006

Cell Motil. Cytoskeleton

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Polyamine depletion with the ornithine decarboxylase inhibitor a-difluoromethyl ornithine (DFMO), prevents Rac1 activation causing the formation of a thick actin cortex at the cell periphery and inhibits migration of intestinal epithelial cells. In the present study, we demonstrate that MEK activation by EGF increased Rac1 activation, dissociation of intercellular contacts, and migration in both control and polyamine-depleted cells, while U0126, a specific inhibitor of MEK1, prevented disruption of junctions as well as EGF-induced Rac1 activation. Constitutively active MEK1 (CA-MEK) expression altered cell-cell contacts in control and polyamine depleted cells. The expression of constitutively active Rac1 (CA-Rac1) restored b-catenin to the cell periphery and prevented the formation of actin cortex and caused the appearance of F-actin stress fibers in polyamine-depleted cells. Inhibition of Rac activation by NSC23766, a specific inhibitor of Tiam1, an upstream guanidine nucleotide exchange factor for Rac1, reproduced the b-catenin localization and actin structure of polyamine-depleted cells. Tiam1 localized more extensively with b-catenin at the cell periphery in CA-Rac1 cells compared to vector cells. Polyamine depletion decreased the expression of E-cadherin to a greater extent compared to b-catenin. Subcellular fractionation further confirmed our immuno-localization and western blotting observations. These data suggest that EGF acting through MEK1/ERK to activate Rac1 regulates cell-cell contacts. Thus, decreased migration in polyamine depleted cells may be due to the inhibition of Tiam1 activation of Rac1 and the subsequent decreased expression of b-catenin and E-cadherin leading to reduced cell-cell contacts. Cell Motil.

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“…Polyamine depletion in tumor cells also alters the response to other chemotherapeutic agents, depending on the apoptotic stimulus and cell type (39). For example, polyamine-depleted IEC-6 rat intestinal epithelial cells show increased susceptibility to apoptosis induced by staurosporin but are protected from apoptosis induced by tumor necrosis factor-a or camptothecin (40,41). Many chemotherapeutic agents affected by polyamine levels target cell cycle checkpoints or chromatin, which are altered in tumor cells.…”

Section: Discussionmentioning

confidence: 99%

Ornithine decarboxylase activity in tumor cell lines correlates with sensitivity to cell death induced by histone deacetylase inhibitors

Saunders

Verdin

2006

Molecular Cancer Therapeutics

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Inhibitors of histone deacetylases (HDAC) show significant promise as targeted anticancer agents against a variety of hematologic and solid tumors. HDAC inhibitors arrest the growth of primary cells, but they induce apoptosis or differentiation of tumor cells. Although the precise mechanism is unknown, differences in cell cycle checkpoints and chromatin structure may be responsible. Cellular polyamines regulate both cell cycle progression and chromatin structure. In tumors, polyamines are abundantly produced because of increased activity of the rate-limiting enzyme in polyamine synthesis, ornithine decarboxylase (ODC). To determine if polyamines contribute to the cellular response to HDAC inhibitors, we inhibited ODC activity with A-difluoromethylornithine. Polyamine depletion increased resistance to apoptosis induced by HDAC inhibitors. In addition, we found that ODC activity levels correlated with sensitivity to HDAC inhibitors in a panel of tumor cell lines. We conclude that polyamines participate in the cellular response to HDAC inhibitors and that ODC activity correlates with sensitivity to HDAC inhibitor -induced apoptosis. Thus, elevated polyamine levels might be a biomarker for tumor sensitivity to HDAC inhibitor -induced apoptosis. These findings warrant clinical evaluation of tumor samples to determine if high ODC activity levels predict sensitivity to HDAC inhibitors.

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Polyamine depletion delays apoptosis of rat intestinal epithelial cells

Cited by 68 publications

References 60 publications

Polyamine Depletion Induces Rapid NF-κB Activation in IEC-6 Cells

Polyamine Depletion Induces Rapid NF-κB Activation in IEC-6 Cells

MEK/ERK regulates adherens junctions and migration through Rac1

Ornithine decarboxylase activity in tumor cell lines correlates with sensitivity to cell death induced by histone deacetylase inhibitors

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