Mamaeva Olga A, Kim Junghyun, Feng Gong, McDonald Jay M
Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35249-7331, USA.
J Cell Biochem. 2009 Jan 1;106(1):25-32. doi: 10.1002/jcb.21973.
Notch signaling is associated with prostate osteoblastic bone metastases and calcium/calmodulin-dependent kinase II (CaMKII) is associated with osteoblastogenesis of human mesenchymal stem cells. Here we show that prostate cancer cell lines C4-2B and PC3, both derived from bone metastases and express Notch-1, have all four isoforms of CaMKII (alpha, beta, gamma, delta). In contrast, prostate cancer cell lines LNcaP and DU145, which are not derived from bone metastases and lack the Notch-1 receptor, both lack the alpha isoform of CaMKII. In addition, DU145 cells also lack the beta-isoform. In C4-2B cells, inhibition of CaMKII by KN93 or gamma-secretase by L-685,458 inhibited the formation of the cleaved form of Notch-1 thus inhibiting Notch signaling. KN93 inhibited down stream Notch-1 signaling including Hes-1 gene expression, Hes-1 promoter activity, and c-Myc expression. In addition, both KN93 and L-685,458 inhibited proliferation and Matrigel invasion by C4-2B cells. The activity of gamma-secretase was unaffected by KN93 but markedly inhibited by L-685,458. Inhibition of the expression of alpha, beta, or gamma-isoform by siRNA did not affect Hes-1 gene expression, however when expression of one isoform was inhibited by siRNA, there were compensatory changes in the expression of the other isoforms. Over-expression of CaMKII-alpha increased Hes-1 expression, consistent with Notch-1 signaling being at least partially dependent upon CaMKII. This unique crosstalk between CaMKII and Notch-1 pathways provides new insight into Notch signaling and potentially provides new targets for pharmacotherapeutics.
Notch信号通路与前列腺成骨细胞性骨转移相关，而钙/钙调蛋白依赖性激酶II（CaMKII）与人骨髓间充质干细胞的成骨细胞生成相关。在此我们发现，源自骨转移且表达Notch-1的前列腺癌细胞系C4-2B和PC3具有CaMKII的所有四种亚型（α、β、γ、δ）。相比之下，并非源自骨转移且缺乏Notch-1受体的前列腺癌细胞系LNcaP和DU145均缺乏CaMKII的α亚型。此外，DU145细胞还缺乏β亚型。在C4-2B细胞中，KN93抑制CaMKII或L-685,458抑制γ-分泌酶可抑制Notch-1裂解形式的形成，从而抑制Notch信号通路。KN93抑制Notch-1下游信号通路，包括Hes-1基因表达、Hes-1启动子活性和c-Myc表达。此外，KN93和L-685,458均抑制C4-2B细胞的增殖和基质胶侵袭。γ-分泌酶的活性不受KN93影响，但被L-685,458显著抑制。通过小干扰RNA（siRNA）抑制α、β或γ亚型的表达并不影响Hes-1基因表达，然而，当一种亚型的表达被siRNA抑制时，其他亚型的表达会发生代偿性变化。CaMKII-α的过表达增加了Hes-1表达，这与Notch-1信号通路至少部分依赖于CaMKII一致。CaMKII与Notch-1通路之间这种独特的相互作用为Notch信号通路提供了新的见解，并可能为药物治疗提供新的靶点。
