Tags

Type your tag names separated by a space and hit enter

Smac induces cytochrome c release and apoptosis independently from Bax/Bcl-x(L) in a strictly caspase-3-dependent manner in human carcinoma cells.
Oncogene 2004; 23(26):4523-35O

Abstract

The mitochondrial apoptosis pathway mediates cell death through the release of various pro-apoptotic factors including cytochrome c and Smac, the second mitochondrial activator of caspases, into the cytosol. Smac was shown previously to inhibit IAP proteins and to facilitate initiation of the caspase cascade upon cytochrome c release. To investigate Smac function during apoptosis and to explore Smac as an experimental cancer therapeutic, we constructed an expression system based on a single adenoviral vector containing Smac under control of the Tet-off system supplied in cis. Conditional expression of Smac induced apoptosis in human HCT116 and DU145 carcinoma cells regardless of the loss of Bax or overexpression of Bcl-x(L). Nevertheless, apoptosis induced by Smac was associated with cytochrome c release and breakdown of the mitochondrial membrane potential. This indicates that Smac acts independently of Bax and Bcl-x(L) during initiation of apoptosis and triggers a positive feedback loop that results in Bax/Bcl-x(L)-independent activation of mitochondria. In caspase-proficient cells, Smac-induced apoptosis could be inhibited partially by cell-permeable LEHD (caspase-9 inhibitor) and DEVD (caspase-3 inhibitor) peptides. Furthermore, loss of caspase-3 expression in MCF-7 cells carrying a caspase-3 null mutation completely abrogated the sensitivity for Smac-induced apoptotic or nonapoptotic, necrosis-like cell death, while re-expression of caspase-3 conferred sensitivity. Altogether, caspase-3 but not caspase-9 activation was necessary for execution of Smac-induced cell death. Notably, Smac did not induce caspase-9 processing in the absence of caspase-3. Thus, caspase-9 processing occurs secondary to caspase-3 activation during Smac-induced apoptosis. Altogether, Smac is capable of circumventing defects in mitochondrial apoptosis signaling such as loss of Bax or overexpression of Bcl-x(L) that are frequently observed in tumor cells resistant to anticancer therapy. Consequently, Smac appears to be a promising therapeutic target in anticancer treatment.

Authors+Show Affiliations

Department of Hematology Oncology and Tumor Immunology, University Medical Center Charité, Campus Berlin-Buch, Humboldt University, Berlin, Germany.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

15064710

Citation

Hasenjäger, Anne, et al. "Smac Induces Cytochrome C Release and Apoptosis Independently From Bax/Bcl-x(L) in a Strictly Caspase-3-dependent Manner in Human Carcinoma Cells." Oncogene, vol. 23, no. 26, 2004, pp. 4523-35.
Hasenjäger A, Gillissen B, Müller A, et al. Smac induces cytochrome c release and apoptosis independently from Bax/Bcl-x(L) in a strictly caspase-3-dependent manner in human carcinoma cells. Oncogene. 2004;23(26):4523-35.
Hasenjäger, A., Gillissen, B., Müller, A., Normand, G., Hemmati, P. G., Schuler, M., ... Daniel, P. T. (2004). Smac induces cytochrome c release and apoptosis independently from Bax/Bcl-x(L) in a strictly caspase-3-dependent manner in human carcinoma cells. Oncogene, 23(26), pp. 4523-35.
Hasenjäger A, et al. Smac Induces Cytochrome C Release and Apoptosis Independently From Bax/Bcl-x(L) in a Strictly Caspase-3-dependent Manner in Human Carcinoma Cells. Oncogene. 2004 Jun 3;23(26):4523-35. PubMed PMID: 15064710.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Smac induces cytochrome c release and apoptosis independently from Bax/Bcl-x(L) in a strictly caspase-3-dependent manner in human carcinoma cells. AU - Hasenjäger,Anne, AU - Gillissen,Bernhard, AU - Müller,Antje, AU - Normand,Guillaume, AU - Hemmati,Philipp G, AU - Schuler,Martin, AU - Dörken,Bernd, AU - Daniel,Peter T, PY - 2004/4/6/pubmed PY - 2004/7/10/medline PY - 2004/4/6/entrez SP - 4523 EP - 35 JF - Oncogene JO - Oncogene VL - 23 IS - 26 N2 - The mitochondrial apoptosis pathway mediates cell death through the release of various pro-apoptotic factors including cytochrome c and Smac, the second mitochondrial activator of caspases, into the cytosol. Smac was shown previously to inhibit IAP proteins and to facilitate initiation of the caspase cascade upon cytochrome c release. To investigate Smac function during apoptosis and to explore Smac as an experimental cancer therapeutic, we constructed an expression system based on a single adenoviral vector containing Smac under control of the Tet-off system supplied in cis. Conditional expression of Smac induced apoptosis in human HCT116 and DU145 carcinoma cells regardless of the loss of Bax or overexpression of Bcl-x(L). Nevertheless, apoptosis induced by Smac was associated with cytochrome c release and breakdown of the mitochondrial membrane potential. This indicates that Smac acts independently of Bax and Bcl-x(L) during initiation of apoptosis and triggers a positive feedback loop that results in Bax/Bcl-x(L)-independent activation of mitochondria. In caspase-proficient cells, Smac-induced apoptosis could be inhibited partially by cell-permeable LEHD (caspase-9 inhibitor) and DEVD (caspase-3 inhibitor) peptides. Furthermore, loss of caspase-3 expression in MCF-7 cells carrying a caspase-3 null mutation completely abrogated the sensitivity for Smac-induced apoptotic or nonapoptotic, necrosis-like cell death, while re-expression of caspase-3 conferred sensitivity. Altogether, caspase-3 but not caspase-9 activation was necessary for execution of Smac-induced cell death. Notably, Smac did not induce caspase-9 processing in the absence of caspase-3. Thus, caspase-9 processing occurs secondary to caspase-3 activation during Smac-induced apoptosis. Altogether, Smac is capable of circumventing defects in mitochondrial apoptosis signaling such as loss of Bax or overexpression of Bcl-x(L) that are frequently observed in tumor cells resistant to anticancer therapy. Consequently, Smac appears to be a promising therapeutic target in anticancer treatment. SN - 0950-9232 UR - https://www.unboundmedicine.com/medline/citation/15064710/Smac_induces_cytochrome_c_release_and_apoptosis_independently_from_Bax/Bcl_x_L__in_a_strictly_caspase_3_dependent_manner_in_human_carcinoma_cells_ L2 - http://dx.doi.org/10.1038/sj.onc.1207594 DB - PRIME DP - Unbound Medicine ER -