[Effect of As2O3 on demethylation of SHP-1 gene in human lymphoma cell line T2].

Background and Objective: Inducing gene demethylation may be a mechanism of arsenic trioxide (As(2)O(3)) in treating hematologic cancers. This study was to investigate the effect of As(2)O(3) on demethylation of SH2-containing phosphatase-1 (SHP-1) in human lymphoma cell line T2 and on the proliferation of T2 cells.
Methods: T2 cells were treated with As(2)O(3) and 5-aza-2'-deoxyoytidine (5-AC) alone or in combination. The methylation of SHP-1 in T2 cells was detected by methylation-specific polymerase chain reaction (MSP). The mRNA and protein expression of SHP-1 were determined by fluorescence quantitative-polymerase chain reaction (FQ-PCR) and Western blot. The expression of p-c-kit was detected by Western blot. Cell proliferation was detected by MTT assay. Cell apoptosis was detected by flow cytometry.
Results: As(2)O(3) led to progressive demethylation and re-expression of SHP-1 in T2 cells, as well as down-regulation of phosphorylated c-kit. As(2)O(3) inhibited the proliferation and promoted the apoptosis of T2 cells, and its effects were enhanced along with the increase of concentration and treatment time (p<0.05). The proliferation inhibition rates were significantly lower in As(2)O(3) (2.5 micromol/L) group than in combination (2.5 micromol/L As(2)O(3) plus 2 micromol/L 5-AC) group (9.8% vs. 11.0%on Day 1, 20.3% vs. 36.7% on Day 2, 47.5% vs. 61.0% on Day 3, p<0.05). The apoptosis rates were significantly higher in combination group than in As(2)O(3) group (17.3% vs. 6.1% on Day 1, 37.9% vs. 26.5% on Day 2, 67.9% vs. 50.9% on Day 3, p<0.05).
Conclusions: As(2)O(3) could cause demethylation and re-expression of SHP-1 in T2 cells, and may inhibit proliferation and induce apoptosis of T2 cells via suppressing activation of c-kit receptor and its signal transduction.