Modulation of Telomerase Activity and Human Telomerase Reverse Transcriptase Expression by Caspases and Bcl-2 Family Proteins in Cisplatin-Induced Cell Death.
10.3343/kjlm.2006.26.4.287
- Author:
Yuk Pheel PARK
1
;
Seung Chul CHOI
;
Mi Young CHO
;
Eun Young SONG
;
Jae Wha KIM
;
Sang Gi PAIK
;
Young Kwon KIM
;
Jong Wan KIM
;
Hee Gu LEE
Author Information
1. Cellomics Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Korea. hglee@kribb.re.kr
- Publication Type:Original Article
- Keywords:
Apoptosis;
Cisplatin;
hTERT;
Bcl-2;
Bak
- MeSH:
Apoptosis;
Caspases*;
Catalytic Domain;
Cell Death*;
Cisplatin;
HEK293 Cells;
HeLa Cells;
Humans*;
Ribonucleoproteins;
Telomerase*;
Trypan Blue
- From:The Korean Journal of Laboratory Medicine
2006;26(4):287-293
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND: Human telomerase is a ribonucleoprotein polymerase, which synthesizes telomeric repeat sequences, and human telomerase reverse transcriptase (hTERT) has been identified as the catalytic subunit, as well as the rate-limiting component, of telomerase. In this study, we attempted to identify the modulators of telomerase, and to determine the molecular mechanisms underlying cisplatin-induced apoptosis. METHODS: To determine the role of telomerase in cisplatin-induced apoptosis, we measured telomerase activity and analyzed apoptosis using PI and trypan blue staining. Also, we inhibited the caspase activations using Z-VAD-fmk to analyze the effects on expression of hTERT protein. Finally, we induced the transient co-expression of the Bcl-2 and Bak genes in HEK293 cells, and then, the telomerase activity and expression of hTERT were evaluated. RESULTS: In the Bcl-2-overexpressing HeLa cells, telomerase activity was more enhanced, and cell death was reduced to 40-50% that of the mock controls. This finding suggests that Bcl-2-induced telomerase activity exerts an antiapoptotic effect in cisplatin-induced death. As caspase activation was inhibited via Z-VAD-fmk, the hTERT protein was recovered in the mock controls, but not in the Bcl-2-overexpressing cells. This suggests that the expression of hTERT can be regulated by caspases, but Bcl-2 was located within the upstream pathway. Moreover, when the Bcl-2 and Bak genes were co-transfected into the HEK293, both telomerase activity and hTERT protein were prominently reduced. CONCLUSIONS: Bcl-2-induced telomerase activity inhibits cisplatin-induced apoptosis in HeLa cells, and can be regulated via both caspases and the interaction of Bcl-2 and Bak.
