Department of Pediatrics, Division of Hematology, Oncology and Blood and Marrow Transplantation, The Saban Research Institute at Children's Hospital Los Angeles and Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
Department of Pediatrics, Division of Hematology, Oncology and Blood and Marrow Transplantation, The Saban Research Institute at Children's Hospital Los Angeles, Los Angeles, California, USA.
Sci Rep. 2019 Sep 25;9(1):13902. doi: 10.1038/s41598-019-50157-5.
G-protein coupled receptor kinase 2 (GRK2; ADRBK1, BARK1) is most known as a regulator of G-protein coupled receptors. However, GRK2 also has other functions. Medulloblastomas are the most common malignant brain cancers in children. GRK2 has not been implicated in medulloblastoma biology. Here we report that GRK2 knockdown slowed cell growth, diminished proliferation, and enhanced cisplatin- and etoposide-induced apoptosis in medulloblastoma cell lines UW228-2 and Daoy. Reciprocally, GRK2 overexpression attenuated apoptosis induced by these chemotherapy drugs. Cisplatin and etoposide increased phosphorylation of AKT (S473) and GRK2 knockdown mitigated this increase. Cisplatin and etoposide attenuated ERK phosphorylation, but GRK2 knockdown did not alter this effect. Wildtype GRK2 reversed the increase in cisplatin- and etoposide-induced apoptosis caused by GRK2 knockdown. GRK2-K220R (kinase dead) and GRK2-S670A (unphosphorylated, constitutively active) conferred protection from cisplatin that was similar to wildtype GRK2, suggesting that this protection may be mediated though a kinase-independent activity of GRK2. These data demonstrate that GRK2 contributes to proliferation and survival of these medulloblastoma cell lines and to their protection from cisplatin- and etoposide-induced apoptosis.
G 蛋白偶联受体激酶 2（GRK2；ADRBK1，BARK1）最常被认为是 G 蛋白偶联受体的调节剂。然而，GRK2 还有其他功能。髓母细胞瘤是儿童中最常见的恶性脑癌。GRK2 尚未涉及髓母细胞瘤生物学。在这里，我们报告 GRK2 敲低可减缓细胞生长、减少增殖，并增强髓母细胞瘤细胞系 UW228-2 和 Daoy 中顺铂和依托泊苷诱导的细胞凋亡。相反，GRK2 过表达可减弱这些化疗药物诱导的细胞凋亡。顺铂和依托泊苷增加 AKT（S473）的磷酸化，而 GRK2 敲低减轻了这种增加。顺铂和依托泊苷减弱 ERK 磷酸化，但 GRK2 敲低没有改变这种作用。野生型 GRK2 逆转了 GRK2 敲低引起的顺铂和依托泊苷诱导的细胞凋亡增加。GRK2-K220R（激酶失活）和 GRK2-S670A（未磷酸化，组成型激活）赋予对顺铂的保护作用与野生型 GRK2 相似，这表明这种保护可能是通过 GRK2 的激酶非依赖性活性介导的。这些数据表明，GRK2 有助于这些髓母细胞瘤细胞系的增殖和存活，并有助于它们免受顺铂和依托泊苷诱导的凋亡。
