Department of Histology-Embryology, Medical School, University of Crete, Heraklion, Greece.
Cancer Lett. 2011 Dec 22;312(2):235-44. doi: 10.1016/j.canlet.2011.08.016. Epub 2011 Aug 22.
Low molecular weight heparin (LMWH) has significant antimetastatic capabilities and affects cancer progression in humans through, not fully defined mechanisms. Here we evaluated its activity at the intracellular level and how it is correlated with melanoma cell adhesion and migration. LMWH inhibited M5 and A375 melanoma cell adhesion and migration in a dose-dependent manner (p⩽0.01). Treatment of M5 melanoma cells with LMWH caused a marked down regulation of constitutive as well as the FN-induced phosphorylation (p⩽0.01) of protein kinase C alpha (PKCa). This was associated with a profound decrease in the cytoplasmic pPKCa (p⩽0.05) and a simultaneous enhancement of nuclear pPKCa localization (p⩽0.01). A significant decrease in the levels of pJNK (p⩽0.01), which is a downstream effector of PKCa, was also demonstrated in the LMWH-treated cells. Furthermore, LMWH-treated cells had disorganized actin stress fibers correlated to a strong decrease in cell-substratum interface area (p⩽0.05) and altered morphology. The decrease in the activation of PKCa, which is an important regulator of cell motility, was directly correlated to the reduced ability of the LMWH-treated melanoma cells to adhere onto and migrate towards the fibronectin (FN) substrate (p⩽0.01). The lineage activation of PKCa-JNK/p38 and their correlation to M5 cell adhesion was confirmed with the utilization of specific inhibitors. In conclusion, LMWH through the downregulation of pPKCa and redistribution to nuclear region attenuates JNK activation, which in turn induces cytoskeleton changes correlated to M5 cell decreased adhesion/migration. This may provide clues for the pharmacological targeting of melanoma.
低分子量肝素（LMWH）具有显著的抗转移能力，并通过尚未完全明确的机制影响人类癌症的进展。在这里，我们评估了其在细胞内的活性，以及它与黑色素瘤细胞黏附和迁移的相关性。LMWH 以剂量依赖的方式抑制 M5 和 A375 黑色素瘤细胞的黏附和迁移（p ⩽ 0.01）。用 LMWH 处理 M5 黑色素瘤细胞会导致组成型和 FN 诱导的蛋白激酶 C 阿尔法（PKCa）磷酸化明显下调（p ⩽ 0.01）。这与细胞质 pPKCa 的深刻减少（p ⩽ 0.05）和核内 pPKCa 定位的同时增强（p ⩽ 0.01）相关。还证明了 LMWH 处理的细胞中 pJNK（p ⩽ 0.01）水平显著下降，这是 PKCa 的下游效应物。此外，LMWH 处理的细胞中的肌动蛋白应力纤维紊乱，与细胞-基质界面区域的强烈减少（p ⩽ 0.05）和形态改变相关。PKCa 的激活减少，这是细胞迁移的重要调节剂，与 LMWH 处理的黑色素瘤细胞黏附到纤维连接蛋白（FN）基质和向其迁移的能力降低直接相关（p ⩽ 0.01）。利用特异性抑制剂证实了 PKCa-JNK/p38 的谱系激活及其与 M5 细胞黏附的相关性。总之，LMWH 通过下调 pPKCa 并重新分布到核区域来减弱 JNK 的激活，这反过来又诱导与 M5 细胞黏附/迁移减少相关的细胞骨架变化。这可能为黑色素瘤的药物靶向提供线索。
