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Published on: May 27, 2011
Arsenic trioxide and the growth of human T-cell leukemia virus type I infected T-cell lines
K Ishitsuka1, S Hanada, K Uozumi
12nd Department of Internal Medicine, Faculty of Medicine, Kagoshima University, Kagoshima, Japan. kishkoj@med6.kufm.kagoshima-u.ac.jp
Abstract:
A novel therapeutic potential for acute promyelocytic leukemia using arsenic trioxide (As(2) O(3) ) has been reported. Recent in vitro studies demonstrated that As(2) O(3) effectively inhibits the growth of some cell lines derived from patients with malignant lymphoma, chronic lymphocytic leukemia and multiple myeloma. Adult T-cell leukemia (ATL) is an aggressive neoplasm of mature T-cell origin caused by human T-cell leukemia virus type-I (HTLV-I) the prognosis of which still remains very poor. A possible role of As(2) O(3) for the treatment of ATL is demonstrated from evidence that As(2) O(3) significantly inhibits the growth of HTLV-I infected T-cell lines and induces apoptosis in fresh ATL cells at clinically achievable concentration of the agent. The growth inhibition of As(2) O(3) treated HTLV-I infected T-cell lines was induced by both apoptosis and G(1) phase accumulation. Cleaved bcl-2 protein and an enhanced expression of bak protein in the cells were coincidentally observed during As(2) O(3) treatment. A broad spectrum caspase inhibitor, z-Val-Ala-DL-Asp-fluoromethylketone inhibited the apoptosis induced by As(2) O(3). Increased expression of p53, Cip1/p21 and Kip1/p27, and dephosphorylation of retinoblastoma protein (pRb) were detected in the As(2) O(3) treated cells. In conclusion, As(2) O(3) might become a new therapeutic tool in the treatment of ATL as As(2) O(3) induces apoptosis by destruction of the bcl-2 protein and enhancement of the bak protein production proceeding to activate caspases, and also induces G(1) phase accumulation by enhancement of p53, Cip1/p21, Kip1/p27 and dephosphorylation of pRb to HTLV-I infected T-cell lines.
Insights
Arsenic trioxide (As(2)O(3)) shows promise for treating Adult T-cell Leukemia (ATL). This agent inhibits cancer cell growth and induces apoptosis, offering a potential new therapy for this aggressive disease.
Area of Science:
- Oncology
- Hematology
- Molecular Biology
Background:
- Adult T-cell Leukemia (ATL) is an aggressive T-cell malignancy with a poor prognosis.
- Current treatment options for ATL are limited, necessitating novel therapeutic strategies.
Purpose of the Study:
- To investigate the therapeutic potential of arsenic trioxide (As(2)O(3)) in treating Adult T-cell Leukemia (ATL).
- To elucidate the mechanisms by which As(2)O(3) affects ATL cells.
Main Methods:
- In vitro studies using HTLV-I infected T-cell lines and fresh ATL cells.
- Analysis of cell growth inhibition, apoptosis induction, cell cycle progression, and protein expression (bcl-2, bak, p53, Cip1/p21, Kip1/p27, pRb).
- Assessment of caspase activation using a broad-spectrum caspase inhibitor.
Main Results:
- As(2)O(3) significantly inhibited the growth of HTLV-I infected T-cell lines and induced apoptosis in fresh ATL cells at clinically achievable concentrations.
- Growth inhibition was mediated by apoptosis and G1 phase cell cycle accumulation.
- As(2)O(3) treatment led to bcl-2 destruction, enhanced bak protein expression, caspase activation, increased p53, Cip1/p21, Kip1/p27, and dephosphorylation of pRb.
Conclusions:
- As(2)O(3) demonstrates significant anti-leukemic activity against ATL cells in vitro.
- The mechanism involves induction of apoptosis via modulation of bcl-2/bak proteins and caspase activation.
- As(2)O(3) also induces G1 cell cycle arrest through p53 and pRb pathway activation, suggesting its potential as a novel therapeutic agent for ATL.
