Thymoquinone Suppresses Cell Proliferation and Enhances Apoptosis of HL60 Leukemia Cells through Re-Expression of JAK/STAT Negative Regulators.

OBJECTIVE The natural compound, thymoquinone (TQ) has demonstrated potential anticancer properties in inhibiting cell proliferation and promoting apoptosis in myeloid leukemia cells, breast cancer cells, and others. However, the effect mechanism of TQ on AML cells still not fully understood. In this study, the authors examined the effects of TQ on the expression of JAK/STAT-negative regulator genes SOCS-1, SOCS-3, and SHP-1, and their consequences on cell proliferation and apoptosis in HL60 leukemia cells. METHODS MTT and trypan blue exclusion tests were conducted to determine the 50% inhibitory concentration (IC50) and cell proliferation. FITC Annexin and Guava® reagent were used to study the cell apoptosis and examine the cell cycle phases, respectively. The expression of JAK/STAT-negative regulator genes, SOCS-1, SOCS-3, and SHP-1, was investigated using reverse transcriptase- quantitative PCR (RT-qPCR). RESULTS TQ demonstrated a potential inhibition of HL60 cell proliferation and a significant increase in apoptotic cells in dose and time-dependent manner. TQ significantly induced cycle arrest at G0-G1 phase (P .