Futami Hitoyasu, Sakai Ryuichi
Growth Factor Division, National Cancer Center Research Institute, 5-1-1, Tsukiji, Chuo-ku, Tokyo 104-0044, Japan.
Cancer Sci. 2009 Jun;100(6):1034-9. doi: 10.1111/j.1349-7006.2009.01143.x. Epub 2009 Feb 20.
The receptor tyrosine kinase RET is expressed in a number of neuroblastoma tissues and cell lines, but its role in neuroblastoma remains to be determined. In this study, we examined the roles of RET protein in neuroblastoma by the RNA interference technique using the NB-39-nu neuroblastoma cell line. NB-39-nu neuroblastoma cells show high expression and elevated tyrosine phosphorylation of RET, although short interfering RNA against RET (RET siRNA) did not significantly inhibit cell proliferation or suppression of basal levels of phosphorylation of extracellular regulated kinase (ERK)1/2 or protein kinase B (AKT). By the addition of glial cell line-derived neurotrophic factor (GDNF), both the expression and phosphorylation of RET and the phosphorylation of ERK1/2 and AKT were further increased, whereas cell proliferation was not stimulated under normal culture conditions. However, proliferation of cells cultured under non-adherent conditions was significantly increased by GDNF. The increased proliferation was suppressed by RET siRNA, which also caused inhibition of the phosphorylation of ERK1/2 and AKT. These results suggest that RET signaling plays an important role in GDNF-induced enhancement of non-adherent proliferation of NB-39-nu cells, which might contribute to the metastasis of neuroblastoma.
受体酪氨酸激酶RET在许多神经母细胞瘤组织和细胞系中表达，但其在神经母细胞瘤中的作用尚待确定。在本研究中，我们使用NB-39-nu神经母细胞瘤细胞系，通过RNA干扰技术研究了RET蛋白在神经母细胞瘤中的作用。NB-39-nu神经母细胞瘤细胞显示RET高表达且酪氨酸磷酸化增强，尽管针对RET的小干扰RNA（RET siRNA）并未显著抑制细胞增殖，也未抑制细胞外调节激酶（ERK）1/2或蛋白激酶B（AKT）的基础磷酸化水平。通过添加胶质细胞系源性神经营养因子（GDNF），RET的表达和磷酸化以及ERK1/2和AKT的磷酸化均进一步增加，而在正常培养条件下细胞增殖未受刺激。然而，在非贴壁条件下培养的细胞增殖被GDNF显著增强。RET siRNA可抑制这种增殖增加，同时还可抑制ERK1/2和AKT的磷酸化。这些结果表明，RET信号在GDNF诱导的NB-39-nu细胞非贴壁增殖增强中起重要作用，这可能有助于神经母细胞瘤的转移。
