Nobiletin Down-Regulates c-KIT Gene Expression and Exerts Antileukemic Effects on Human Acute Myeloid Leukemia Cells
Pei-Yi Chen1, Yu-Ting Chen2, Wan-Yun Gao2
1Center of Medical Genetics , Buddhist Tzu Chi General Hospital , Hualien 970 , Taiwan.
Abstract:
Nobiletin, a dietary citrus flavonoid, has been reported to possess several biological activities such as antioxidant, anti-inflammatory, and anticancer properties. The aim of this study was to investigate the antileukemic effects of nobiletin and its underlying mechanisms on human acute myeloid leukemia (AML) cells. We demonstrated that nobiletin (0-100 μM) significantly reduced cell viability from 100.0 ± 9.6% to 31.1 ± 2.8% in human AML THP-1 cell line. Nobiletin arrested cell cycle progression in G1 phase and induced myeloid cell differentiation in human AML cells. Microarray analysis showed that mRNA expression of the c- KIT gene, a critical proto-oncogene associated with leukemia progression, was dramatically reduced in nobiletin-treated AML cells. Furthermore, we verified that AML cells treated with nobiletin (40 and 80 μM) for 48 h markedly suppressed c-KIT mRNA expression (from 1.00 ± 0.07-fold to 0.62 ± 0.08- and 0.30 ± 0.05-fold) and reduced the level of c-KIT protein expression (from 1.00 ± 0.11-fold to 0.60 ± 0.15- and 0.34 ± 0.05-fold) by inhibition of KIT promoter activity. The knockdown of c-KIT expression by shRNA attenuated cancer cell growth and induced cell differentiation. Moreover, we found that the overexpression of c-KIT abolished nobiletin-mediated cell growth inhibition in leukemia cells. These results indicate that nobiletin exerts antileukemic effects through the down-regulation of c-KIT gene expression in AML cells. Finally, we demonstrated that the combination of a conventional AML chemotherapeutic agent, cytarabine, with nobiletin resulted in more reduction of cell viability in AML cells. Our current findings suggest that nobiletin is a novel c-KIT inhibitor and may serve as a chemo-preventive or -therapeutic agent against human AML.
Insights
Nobiletin, a citrus flavonoid, effectively inhibits human acute myeloid leukemia (AML) cell growth by down-regulating the c-KIT gene. This natural compound shows promise as a novel therapeutic agent for AML.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Nobiletin, a citrus flavonoid, exhibits antioxidant, anti-inflammatory, and anticancer properties.
- Acute myeloid leukemia (AML) is a significant hematological malignancy with a need for novel therapeutic strategies.
Purpose of the Study:
- To investigate the antileukemic effects of nobiletin on human AML cells.
- To elucidate the underlying molecular mechanisms of nobiletin's action, particularly its effect on c-KIT gene expression.
Main Methods:
- Human AML THP-1 cell line was treated with varying concentrations of nobiletin.
- Cell viability, cell cycle progression, and myeloid cell differentiation were assessed.
- Microarray analysis and quantitative PCR were used to evaluate c-KIT gene expression.
- Western blotting and promoter activity assays were performed to confirm protein expression and inhibition.
- c-KIT knockdown and overexpression studies were conducted.
Main Results:
- Nobiletin significantly reduced AML cell viability in a dose-dependent manner.
- Nobiletin induced G1 phase cell cycle arrest and promoted myeloid cell differentiation.
- Nobiletin markedly suppressed both c-KIT mRNA and protein expression by inhibiting KIT promoter activity.
- Knockdown of c-KIT attenuated cancer cell growth and induced differentiation, while its overexpression abolished nobiletin's inhibitory effects.
- Combination therapy with cytarabine and nobiletin enhanced cell viability reduction.
Conclusions:
- Nobiletin exerts significant antileukemic effects in human AML cells.
- The primary mechanism involves the down-regulation of c-KIT gene expression.
- Nobiletin acts as a novel c-KIT inhibitor and holds potential as a chemo-preventive or therapeutic agent for AML.
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