Telomere attrition and chromosome instability via downregulation of TRF2 contributes to arsenic trioxide-induced apoptosis of human T-Cell leukemia cell line molt-4 cells.

Abstract

Overexpression of human telomere repeat binding factor 2 (TRF2), which may play an important role in the fate of cancer cells, has been observed in adult T-cell leukemia. Previous reports have shown that the inhibition of TRF2 results in the apoptosis of cancer cells. In this study, we demonstrated that arsenic trioxide (As2O3) induced in vitro growth inhibition and/or apoptosis of human T-cell leukemia cell line Molt-4 in a caspase-independent manner. Telomerase activity was not inhibited, although the level of the reverse transcriptase subunit of the human telomerase gene (hTERT) mRNA expression was down regulated during the early times and then recovered to the level found in untreated controls about 48 hours after treatment with As2O3. Furthermore, a remarkable telomere shortening related to exposure of As2O3 was observed in 50 population doubling. Inc ontrast, the alteration of telomere length did not occur after exposure to higher concentration of As2O3 (10 microM) for 24 hours and 48 hours, respectively, suggesting that the shortening of telomeres induced by As2O3 is dependent of a series of cell division cycles. Chromosomal analysis showed that As2O3 exposure caused chromosomal end-to-end fusion in human T-cell leukemia cells while downregulation of TRF2 was observed. Finally, the inhibition of TRF2 protein expression and the sensitivity to As2O3 in a panel of leukemia cell lines were checked. The data revealed that inhibition of TRF2 rendered leukemia cells more susceptible to As2O3. In conclusion, the downregulation of TRF2 by As2O3 contribute to chromosomal end-to-end fusion, and apoptosis in leukemia cells, suggesting that TRF2 could be an attractive target for new therapies of leukemia.

• Authors: Yangwen Jiao, Weifang Zhang, Junqing Liu, Wanmao Ni, Weilai Xu, Jie Jin, Wenbin Qian
• Journal: Cancer biology & therapy (Cancer Biol Ther) Vol. 6 Issue 8 Pg. 1186-92 (Aug 2007) ISSN: 1555-8576 [Electronic] United States
• PMID: 17643074 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• Arsenicals
• Oxides
• Telomeric Repeat Binding Protein 2
• TERT protein, human
• Telomerase
• Caspases
• Arsenic Trioxide

Topics

• Antineoplastic Agents (pharmacology)
• Apoptosis
• Arsenic Trioxide
• Arsenicals (pharmacology)
• Caspases (metabolism)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Chromosomal Instability
• Humans
• Leukemia-Lymphoma, Adult T-Cell (genetics, metabolism)
• Oxides (pharmacology)
• Telomerase (antagonists & inhibitors, genetics, metabolism)
• Telomere (drug effects)
• Telomeric Repeat Binding Protein 2 (antagonists & inhibitors, metabolism)