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Protein kinase C inhibition and x-linked inhibitor of apoptosis protein degradation contribute to the sensitization effect of luteolin on tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in cancer cells.
Cancer Res. 2005 Sep 01; 65(17):7815-23.CR

Abstract

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is an important member of the TNF superfamily with great potential in cancer therapy. Luteolin is a dietary flavonoid commonly found in some medicinal plants. Here we found that pretreatment with a noncytotoxic concentration of luteolin significantly sensitized TRAIL-induced apoptosis in both TRAIL-sensitive (HeLa) and TRAIL-resistant cancer cells (CNE1, HT29, and HepG2). Such sensitization is achieved through enhanced caspase-8 activation and caspase-3 maturation. Further, the protein level of X-linked inhibitor of apoptosis protein (XIAP) was markedly reduced in cells treated with luteolin and TRAIL, and ectopic expression of XIAP protected against cell death induced by luteolin and TRAIL, showing that luteolin sensitizes TRAIL-induced apoptosis through down-regulation of XIAP. In search of the molecular mechanism responsible for XIAP down-regulation, we found that luteolin and TRAIL promoted XIAP ubiquitination and proteasomal degradation. Next, we showed that protein kinase C (PKC) activation prevented cell death induced by luteolin and TRAIL via suppression of XIAP down-regulation. Moreover, luteolin inhibited PKC activity, and bisindolylmaleimide I, a general PKC inhibitor, simulated luteolin in sensitizing TRAIL-induced apoptosis. Taken together, these results present a novel anticancer effect of luteolin and support its potential application in cancer therapy in combination with TRAIL. In addition, our data reveal a new function of PKC in cell death: PKC activation stabilizes XIAP and thus suppresses TRAIL-induced apoptosis.

Authors+Show Affiliations

Department of Community, Occupational, and Family Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Republic of Singapore.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16140950

Citation

Shi, Ran-Xin, et al. "Protein Kinase C Inhibition and X-linked Inhibitor of Apoptosis Protein Degradation Contribute to the Sensitization Effect of Luteolin On Tumor Necrosis Factor-related Apoptosis-inducing Ligand-induced Apoptosis in Cancer Cells." Cancer Research, vol. 65, no. 17, 2005, pp. 7815-23.
Shi RX, Ong CN, Shen HM. Protein kinase C inhibition and x-linked inhibitor of apoptosis protein degradation contribute to the sensitization effect of luteolin on tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in cancer cells. Cancer Res. 2005;65(17):7815-23.
Shi, R. X., Ong, C. N., & Shen, H. M. (2005). Protein kinase C inhibition and x-linked inhibitor of apoptosis protein degradation contribute to the sensitization effect of luteolin on tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in cancer cells. Cancer Research, 65(17), 7815-23.
Shi RX, Ong CN, Shen HM. Protein Kinase C Inhibition and X-linked Inhibitor of Apoptosis Protein Degradation Contribute to the Sensitization Effect of Luteolin On Tumor Necrosis Factor-related Apoptosis-inducing Ligand-induced Apoptosis in Cancer Cells. Cancer Res. 2005 Sep 1;65(17):7815-23. PubMed PMID: 16140950.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Protein kinase C inhibition and x-linked inhibitor of apoptosis protein degradation contribute to the sensitization effect of luteolin on tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in cancer cells. AU - Shi,Ran-Xin, AU - Ong,Choon-Nam, AU - Shen,Han-Ming, PY - 2005/9/6/pubmed PY - 2005/11/16/medline PY - 2005/9/6/entrez SP - 7815 EP - 23 JF - Cancer research JO - Cancer Res VL - 65 IS - 17 N2 - Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is an important member of the TNF superfamily with great potential in cancer therapy. Luteolin is a dietary flavonoid commonly found in some medicinal plants. Here we found that pretreatment with a noncytotoxic concentration of luteolin significantly sensitized TRAIL-induced apoptosis in both TRAIL-sensitive (HeLa) and TRAIL-resistant cancer cells (CNE1, HT29, and HepG2). Such sensitization is achieved through enhanced caspase-8 activation and caspase-3 maturation. Further, the protein level of X-linked inhibitor of apoptosis protein (XIAP) was markedly reduced in cells treated with luteolin and TRAIL, and ectopic expression of XIAP protected against cell death induced by luteolin and TRAIL, showing that luteolin sensitizes TRAIL-induced apoptosis through down-regulation of XIAP. In search of the molecular mechanism responsible for XIAP down-regulation, we found that luteolin and TRAIL promoted XIAP ubiquitination and proteasomal degradation. Next, we showed that protein kinase C (PKC) activation prevented cell death induced by luteolin and TRAIL via suppression of XIAP down-regulation. Moreover, luteolin inhibited PKC activity, and bisindolylmaleimide I, a general PKC inhibitor, simulated luteolin in sensitizing TRAIL-induced apoptosis. Taken together, these results present a novel anticancer effect of luteolin and support its potential application in cancer therapy in combination with TRAIL. In addition, our data reveal a new function of PKC in cell death: PKC activation stabilizes XIAP and thus suppresses TRAIL-induced apoptosis. SN - 0008-5472 UR - https://www.unboundmedicine.com/medline/citation/16140950/Protein_kinase_C_inhibition_and_x_linked_inhibitor_of_apoptosis_protein_degradation_contribute_to_the_sensitization_effect_of_luteolin_on_tumor_necrosis_factor_related_apoptosis_inducing_ligand_induced_apoptosis_in_cancer_cells_ L2 - http://cancerres.aacrjournals.org/cgi/pmidlookup?view=long&pmid=16140950 DB - PRIME DP - Unbound Medicine ER -