The role of TC-PTP (PTPN2) in modulating sensitivity to imatinib and interferon-α in CML cell line, KT-1 cells.

T-cell protein tyrosine phosphatase (TC-PTP, also known as PTPN2) is a negative regulator of the JAK/STAT pathway. STAT5 is activated by BCR-ABL kinase and STAT1 is an important transcription factor for interferon (IFN)-α-induced signaling in chronic myeloid leukemia (CML). We used siRNA to delete TC-PTP in the CML cell line, KT-1, and examined changes in the sensitivity to imatinib and IFN-α. Suppression of TC-PTP induced activation of STAT5, leading to imatinib resistance, while prolonged phosphorylation of STAT1 was induced by IFN-α, triggering cell death in KT-1 cells. These findings suggest that TC-PTP modulates sensitivity to imatinib and IFN-α in CML.