Department of Laboratory Medicine, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-Ku, Tokyo 113-8519, Japan.
Anticancer Res. 2013 Oct;33(10):4293-8.
The effects of small interfering RNA (siRNA)-mediated knockdown of NOTCH1 and NOTCH2 on cell proliferation and downstream signaling pathways in leukemia cells were examined.
Two T-lymphoblastic leukemia (T-ALL) cell lines and two acute myeloblastic leukemia (AML) cell lines were transfected with siRNAs targeting NOTCH1 and NOTCH2. The effects of knockdown on cell proliferation and protein expression were examined by colorimetric WST-8 assay and immunoblotting, respectively.
In T-ALL cell lines, NOTCH1 knockdown as well as NOTCH2 knockdown suppressed cell proliferation and induced apoptosis. v-Myc avian myelocytomatosis viral oncogene homolog (MYC) protein expression was down-regulated in NOTCH1-knockdown cells but not affected in NOTCH2-knockdown cells. In AML cell lines, cell proliferation was not significantly affected by NOTCH siRNAs. NOTCH2 knockdown increased the level of cleaved NOTCH1 fragment without increasing NOTCH1 expression. NOTCH knockdown reduced the level of mechanistic target of rapamycin (mTOR) protein in the monoblastic leukemia cell line THP-1. Contrastingly, NOTCH activation by NOTCH ligand stimulation increased the expression of mTOR in THP-1 cells.
These novel findings on NOTCH signaling may contribute to the development of effective NOTCH-targeted therapies against leukemia.
研究小干扰 RNA（siRNA）介导的 NOTCH1 和 NOTCH2 敲低对白血病细胞增殖和下游信号通路的影响。
用靶向 NOTCH1 和 NOTCH2 的 siRNA 转染两种 T 淋巴细胞白血病（T-ALL）细胞系和两种急性髓细胞白血病（AML）细胞系。通过比色 WST-8 测定法和免疫印迹法分别检测敲低对细胞增殖和蛋白表达的影响。
在 T-ALL 细胞系中，NOTCH1 敲低和 NOTCH2 敲低均抑制细胞增殖并诱导细胞凋亡。v-Myc 禽髓细胞瘤病毒癌基因同源物（MYC）蛋白表达在 NOTCH1 敲低细胞中下调，但在 NOTCH2 敲低细胞中不受影响。在 AML 细胞系中，NOTCH siRNA 对细胞增殖没有显著影响。NOTCH2 敲低增加了裂解的 NOTCH1 片段的水平，而没有增加 NOTCH1 的表达。NOTCH 敲低降低了单核白血病细胞系 THP-1 中雷帕霉素（mTOR）蛋白的水平。相反，NOTCH 配体刺激激活 NOTCH 增加了 THP-1 细胞中 mTOR 的表达。
这些关于 NOTCH 信号的新发现可能有助于开发针对白血病的有效 NOTCH 靶向治疗。
