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Endothelin-receptor antagonists are proapoptotic and antiproliferative in human colon cancer cells.

Peduto Eberl L, Bovey R, Juillerat-Jeanneret L - Br. J. Cancer (2003)

Bottom Line: Bosentan and/or FasLigand (FasL) did not modulate the expression of caspase-8 or FLIP.These results suggest that the binding of ET-1 to high-affinity sites inhibits FasL-induced apoptosis, while the binding of either ET-1 or receptor antagonists to low-affinity sites promotes FasL-induced apoptosis.In conclusion, endothelin signalling pathways do not induce human colon cancer cell proliferation, but are survival signals controling resistance to apoptosis.

View Article: PubMed Central - PubMed

Affiliation: University Institute of Pathology, CHUV, University of Lausanne, Bugnon 25, Switzerland.

ABSTRACT
Endothelin (ET)-1 can act as an autocrine/paracrine growth factor or an antiapoptotic factor in human cancers. To study the role of ET-1 in human colon cancer, proliferation and apoptosis of colon carcinoma cells was investigated using human HT-29 and SW480 colon carcinoma cells. ET-1 was secreted by these cells. Treatment of cells with bosentan, a dual ET(A/B)-receptor antagonist, decreased cell number. Inhibition of DNA synthesis by bosentan was observed only in the presence of serum. Exogenously added ET-1 did not increase DNA synthesis in serum-deprived cells. SW480 cells were sensitive and HT-29 cells were resistant to FasL-induced apoptosis. Bosentan sensitised resistant HT-29 cells to FasL-induced, caspase-mediated apoptosis, but not to TNF-alpha-induced apoptosis. Bosentan and/or FasLigand (FasL) did not modulate the expression of caspase-8 or FLIP. Bosentan sensitisation to apoptosis was reversed by low concentrations (10(-13)-10(-10) M), but not by high concentrations (10(-9)-10(-7) M) of ET-1. These results suggest that the binding of ET-1 to high-affinity sites inhibits FasL-induced apoptosis, while the binding of either ET-1 or receptor antagonists to low-affinity sites promotes FasL-induced apoptosis. In conclusion, endothelin signalling pathways do not induce human colon cancer cell proliferation, but are survival signals controling resistance to apoptosis.

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Related in: MedlinePlus

Bosentan sensitisation to FasL-induced apoptosis in HT-29 cells is blocked by the general caspase inhibitor zVAD-fmk. Cells were preincubated with 100 μM zVAD-fmk for 1 h, then 150 μM bosentan (without FasL) or 80 μM bosentan (with FasL) were added. Incubation was continued for 24 h and apoptosis was evaluated. Values are the mean+s.d. of two independent determinations. P<0.01: bosentan+FasL vs control; z-VAD-fmk+bosentan+FasL vs bosentan+FasL.
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fig8: Bosentan sensitisation to FasL-induced apoptosis in HT-29 cells is blocked by the general caspase inhibitor zVAD-fmk. Cells were preincubated with 100 μM zVAD-fmk for 1 h, then 150 μM bosentan (without FasL) or 80 μM bosentan (with FasL) were added. Incubation was continued for 24 h and apoptosis was evaluated. Values are the mean+s.d. of two independent determinations. P<0.01: bosentan+FasL vs control; z-VAD-fmk+bosentan+FasL vs bosentan+FasL.

Mentions: Expression of the FLIP and caspase-8 in HT29 and SW480 cells. (A) HT-29 and SW480 cells express the long and the short FLIP mRNAs. RT–PCR was performed on total RNA extracted from the two tumoral cell lines. (B) Bosentan and FasL do not modulate the expression of the short form of FLIP in SW480 cells. Half-confluent SW480 cells were incubated with bosentan and/or FasL for 24 h and the presence of sFLIP was determined by Western blotting. (C) Bosentan and FasL do not modulate the expression of caspase-8 in HT-29 and SW480 cells exposed to bosentan and FasL. Half-confluent SW480 or HT-29 cells were incubated with bosentan and/or FasL for 24 h and the presence of caspase-8 was determined by Western blotting. Two independent experiments gave similar results.


Endothelin-receptor antagonists are proapoptotic and antiproliferative in human colon cancer cells.

Peduto Eberl L, Bovey R, Juillerat-Jeanneret L - Br. J. Cancer (2003)

Bosentan sensitisation to FasL-induced apoptosis in HT-29 cells is blocked by the general caspase inhibitor zVAD-fmk. Cells were preincubated with 100 μM zVAD-fmk for 1 h, then 150 μM bosentan (without FasL) or 80 μM bosentan (with FasL) were added. Incubation was continued for 24 h and apoptosis was evaluated. Values are the mean+s.d. of two independent determinations. P<0.01: bosentan+FasL vs control; z-VAD-fmk+bosentan+FasL vs bosentan+FasL.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2376352&req=5

fig8: Bosentan sensitisation to FasL-induced apoptosis in HT-29 cells is blocked by the general caspase inhibitor zVAD-fmk. Cells were preincubated with 100 μM zVAD-fmk for 1 h, then 150 μM bosentan (without FasL) or 80 μM bosentan (with FasL) were added. Incubation was continued for 24 h and apoptosis was evaluated. Values are the mean+s.d. of two independent determinations. P<0.01: bosentan+FasL vs control; z-VAD-fmk+bosentan+FasL vs bosentan+FasL.
Mentions: Expression of the FLIP and caspase-8 in HT29 and SW480 cells. (A) HT-29 and SW480 cells express the long and the short FLIP mRNAs. RT–PCR was performed on total RNA extracted from the two tumoral cell lines. (B) Bosentan and FasL do not modulate the expression of the short form of FLIP in SW480 cells. Half-confluent SW480 cells were incubated with bosentan and/or FasL for 24 h and the presence of sFLIP was determined by Western blotting. (C) Bosentan and FasL do not modulate the expression of caspase-8 in HT-29 and SW480 cells exposed to bosentan and FasL. Half-confluent SW480 or HT-29 cells were incubated with bosentan and/or FasL for 24 h and the presence of caspase-8 was determined by Western blotting. Two independent experiments gave similar results.

Bottom Line: Bosentan and/or FasLigand (FasL) did not modulate the expression of caspase-8 or FLIP.These results suggest that the binding of ET-1 to high-affinity sites inhibits FasL-induced apoptosis, while the binding of either ET-1 or receptor antagonists to low-affinity sites promotes FasL-induced apoptosis.In conclusion, endothelin signalling pathways do not induce human colon cancer cell proliferation, but are survival signals controling resistance to apoptosis.

View Article: PubMed Central - PubMed

Affiliation: University Institute of Pathology, CHUV, University of Lausanne, Bugnon 25, Switzerland.

ABSTRACT
Endothelin (ET)-1 can act as an autocrine/paracrine growth factor or an antiapoptotic factor in human cancers. To study the role of ET-1 in human colon cancer, proliferation and apoptosis of colon carcinoma cells was investigated using human HT-29 and SW480 colon carcinoma cells. ET-1 was secreted by these cells. Treatment of cells with bosentan, a dual ET(A/B)-receptor antagonist, decreased cell number. Inhibition of DNA synthesis by bosentan was observed only in the presence of serum. Exogenously added ET-1 did not increase DNA synthesis in serum-deprived cells. SW480 cells were sensitive and HT-29 cells were resistant to FasL-induced apoptosis. Bosentan sensitised resistant HT-29 cells to FasL-induced, caspase-mediated apoptosis, but not to TNF-alpha-induced apoptosis. Bosentan and/or FasLigand (FasL) did not modulate the expression of caspase-8 or FLIP. Bosentan sensitisation to apoptosis was reversed by low concentrations (10(-13)-10(-10) M), but not by high concentrations (10(-9)-10(-7) M) of ET-1. These results suggest that the binding of ET-1 to high-affinity sites inhibits FasL-induced apoptosis, while the binding of either ET-1 or receptor antagonists to low-affinity sites promotes FasL-induced apoptosis. In conclusion, endothelin signalling pathways do not induce human colon cancer cell proliferation, but are survival signals controling resistance to apoptosis.

Show MeSH
Related in: MedlinePlus