Cytokine-induced Apoptosis in Epithelial HT-29 Cells Is Independent of Nitric Oxide Formation

Wright, Karen L.; Kolios, George; Westwick, John; Ward, Stephen G.

doi:10.1074/jbc.274.24.17193

Cited by 79 publications

(27 citation statements)

References 71 publications

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“…Under these conditions no detectable signs of cell death were observed, and a 2.5-fold increase of PTEN proteins was detected using an anti-PTEN antibody (data not shown). IL-13 is known to activate Akt/PKB in HT-29 cells in a class I PI 3-K-dependent manner (13,23). When wt-PTEN-expressing cells were challenged with IL-13 after IPTG addition, we observed a decrease in Akt/PKB phosphorylation when compared with the control cells (Fig.…”

Section: Pten Controls the Il-13-dependent Activation Of Pkb Inmentioning

confidence: 72%

The Tumor Suppressor PTEN Positively Regulates Macroautophagy by Inhibiting the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway

Arico¹,

Petiot²,

Bauvy³

et al. 2001

Journal of Biological Chemistry

531

431

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The tumor suppressor PTEN is a dual protein and phosphoinositide phosphatase that negatively controls the phosphatidylinositol (PI) 3-kinase/protein kinase B (Akt/PKB) signaling pathway. Interleukin-13 via the activation of the class I PI 3-kinase has been shown to inhibit the macroautophagic pathway in the human colon cancer HT-29 cells. Here we demonstrate that the wild-type PTEN is expressed in this cell line. Its overexpression directed by an inducible promoter counteracts the interleukin-13 down-regulation of macroautophagy. This effect was dependent upon the phosphoinositide phosphatase activity of PTEN as determined by using the mutant G129E, which has only protein phosphatase activity. The role of Akt/PKB in the signaling control of interleukin-13-dependent macroautophagy was investigated by expressing a constitutively active form of the kinase ( Myr PKB). Under these conditions a dramatic inhibition of macroautophagy was observed. By contrast a high rate of autophagy was observed in cells expressing a dominant negative form of PKB. These data demonstrate that the signaling control of macroautophagy overlaps with the well known PI 3-kinase/PKB survival pathway and that the loss of PTEN function in cancer cells inhibits a major catabolic pathway.

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Section: Pten Controls the Il-13-dependent Activation Of Pkb Inmentioning

confidence: 72%

The Tumor Suppressor PTEN Positively Regulates Macroautophagy by Inhibiting the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway

Arico¹,

Petiot²,

Bauvy³

et al. 2001

Journal of Biological Chemistry

531

431

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“…Similarly to other cytokines such as IL-2 and IL-3 (42)(43)(44), the IL-13 transduction pathway activates Akt/PKB (Ref. 45 and this study). Nevertheless our results provide no direct evidence that the activation of Akt/ PKB is required for controlling macroautophagic sequestration.…”

Section: Discussionmentioning

confidence: 99%

Distinct Classes of Phosphatidylinositol 3′-Kinases Are Involved in Signaling Pathways That Control Macroautophagy in HT-29 Cells

Petiot¹,

Ogier–Denis²,

Blommaart³

et al. 2000

Journal of Biological Chemistry

1,098

870

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3-Methyladenine which stops macroautophagy at the sequestration step in mammalian cells also inhibits the phosphoinositide 3-kinase (PI3K) activity raising the possibility that PI3K signaling controls the macroautophagic pathway (Blommaart, E. F. C., Krause, U., Schellens, J. P. M., Vreeling-Sindelá rová , H., and Meijer, A. J. Macroautophagy is a major intralysosomal catabolic process conserved during the evolution of eukaryotic cells (1-4). In mammalian cells, the macroautophagic pathway starts with the sequestration of cytoplasmic material (including mitochondria, peroxisomes, smooth and rough membranes, and cytosolic constituents: proteins, glycogen, neutral lipids, RNA, and ribosomes) to form an early autophagosome. The membrane of early autophagosomes is derived from ribosome-free regions of the rough endoplasmic reticulum (5) and/or a related organelle called the phagophore (see Ref. 6 and references therein). After acidification the early autophagosome is transformed in a late autophagosome. Fusion between late autophagosomes and lysosomes triggers the degradation of sequestered material into autolysosomes. Material from the endocytic pathway can be imported in autophagic vacuoles at different steps of their maturation (7,8).Recently, studies have shed light on the intracellular mechanisms that control membrane flow along the autophagic/lysosomal pathway in mammalian cells (reviewed in Refs. 9 and 10). It has been suggested that the phosphoinositide 3-kinase (PI3K) 1 signaling cascade controls macroautophagy (11) and that 3-MA, an inhibitor of macroautophagic sequestration (12), behaves as a PI3K inhibitor.PI3K belongs to a family of enzymes that phosphorylates the 3Ј-hydroxyl group on the inositol ring of phosphoinositides (reviewed in Refs. 13-16). These phospholipids are involved in a large array of signal transduction pathways controlling mitogenic responses, differentiation, apoptosis, cytoskeletal organization, and membrane flow along the secretory and endocytic pathways (reviewed in Ref. 17). PI3Ks are classified into three classes. Class I enzymes are composed of catalytic p110 subunits and p85 adaptors. The SH2 motif contained in p85 adaptors bind to phosphorylated Tyr residues thereby linking the catalytic subunit to the Tyr kinase signaling pathway (class I A ). A member of the class I PI3K family (class I B , p110␥/p101) is activated by subunits of trimeric G proteins (18,19). Class I PI3Ks phosphorylate PtdIns, PtdIns(4)P, PtdIns(4,5)P 2 but in vivo PtdIns(4,5)P 2 is likely to be the favorite substrate. Class II enzymes are large enzymes (Ͼ200 kDa) characterized by a C-terminal containing a C2 domain (20-23). These enzymes phosphorylate in vitro PtdIns, PtdIns(4)P, but not PtdIns(4,5)P 2 . Class III enzymes 1 The abbreviations used are: PI3K, phosphatidylinositol 3-kinase; diC16PtdIns(3)P, dipalmitoyl phosphatidylinositol 3-phosphate; diC16PtdIns(4)P, dipalmitoyl phosphatidylinositol 4-phosphate; diC16Ptd-Ins(3,4)P 2 , dipalmitoyl phosphatidylinositol 3,4-bisphosphate; diC16Pt-dIns(4,5)P 2 ...

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“…In this respect, it is worth noting that pre-incubation with interferon ␥ sensitized HT-29 cells to TNF␣ cytotoxicity. 28,30 One can speculate that interferon ␥ increases not only the synthesis 31 but also the number of TNF receptors at the plasma membrane level. We found that co-treatment with an inhibitor of PKC (␣ and ␤ isoforms) at doses not cytotoxic per se for as long as 48 hr sensitized HT-29 cells to TNF␣ cytotoxicity.…”

Section: Discussionmentioning

confidence: 99%

Expression of protein kinase C ?1 confers resistance to TNF?- and paclitaxel-induced apoptosis in HT-29 colon carcinoma cells

Cesaro¹,

Raiteri²,

Démoz³

et al. 2001

Int. J. Cancer

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The expression of different protein kinase C (PKC) isoenzymes has been shown to vary with proliferation rates, differentiation or apoptosis in normal colon crypts. In addition, the activity of some PKC isoenzymes appears to be reduced in colorectal cancer. The aim of the present work was to determine whether modulation of PKC expression would affect the susceptibility of a p53-defective colon carcinoma cell line to different apoptotic treatments. HT-29 cells exhibited sensitivity to paclitaxel (Taxol) and tumor necrosis factor ␣ (TNF␣) in a dose-and time-dependent manner but were relatively resistant to etoposide. Inhibition of PKC activity augmented the susceptibility of HT-29 cells to apoptosis, and phorbol ester induction of PKC reduced such susceptibility. Key words: protein kinase C; TNF␣; paclitaxel; apoptosis; colon carcinomaColorectal cancer is one of the most common solid tumors world-wide. Due to its high metastatic potential and the frequent onset of resistance to chemotherapy, it is one of the four major causes of death by neoplasia in westernized countries. Loss of function of p53 occurs in more than 75% of human colorectal cancers. Since p53 regulates a complex array of cellular responses to DNA damage, including cell cycle arrest and apoptosis, its loss of function is also expected to affect the sensitivity of tumor cells to DNA-damaging antiblastic drugs. 1,2The expression of different protein kinase C (PKC) isoenzymes varies with proliferation rates, differentiation or apoptosis in normal colon crypts, [3][4][5][6] and the activity of some PKC isoenzymes is reduced in colorectal cancer. [7][8][9] Whether, in addition to loss of function of p53, altered functioning of PKCs contributes to the low sensitivity of colon carcinomas to apoptosis-based chemotherapy remains to be established. In the present work we addressed this issue by examining the effect of various apoptotic treatments on HT-29 colon cancer cells that lack functional p53 10 and either do or do not express abnormal levels of the isoform ␤1 of PKC. We found that paclitaxel (Taxol) and TNF␣, but not etoposide, efficiently induced apoptosis of HT-29 cells in a dose-and timedependent manner.The involvement of PKC in the apoptotic pathways triggered by paclitaxel or TNF␣ was assessed by using a myristoylated pseudosubstrate as inhibitor at doses not affecting cell viability. In HT-29 cells, inhibition of PKC (␣ and ␤ isoforms) activity augmented by twofold the cytotoxicity of both drugs. Induction of PKC by the phorbol ester phorbol myristate acetate (PMA) decreased the susceptibility of HT-29 cells to both TNF␣ and paclitaxel treatments. Resistance to apoptotic treatments was consistently observed in transfected HT-29 cells hyper-expressing PKC␤1. The present data implicate PKC (␣ and ␤) as a component of the mechanism responsible for the resistance of colon carcinoma cells to apoptotic drugs. MATERIAL AND METHODS Cells and chemicalsThe HT-29 human colon cancer cell line was obtained from the American Type Culture Collection (ATCC, Rock...

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Cytokine-induced Apoptosis in Epithelial HT-29 Cells Is Independent of Nitric Oxide Formation

Cited by 79 publications

References 71 publications

The Tumor Suppressor PTEN Positively Regulates Macroautophagy by Inhibiting the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway

The Tumor Suppressor PTEN Positively Regulates Macroautophagy by Inhibiting the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway

Distinct Classes of Phosphatidylinositol 3′-Kinases Are Involved in Signaling Pathways That Control Macroautophagy in HT-29 Cells

Expression of protein kinase C ?1 confers resistance to TNF?- and paclitaxel-induced apoptosis in HT-29 colon carcinoma cells

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