Lamellipodia and Membrane Blebs Drive Efficient Electrotactic Migration of Rat Walker Carcinosarcoma Cells WC 256

The endogenous electric field (EF) may provide an important signal for directional cell migration during wound healing, embryonic development and cancer metastasis but the mechanism of cell electrotaxis is poorly understood. Additionally, there is no research addressing the question on the difference in electrotactic motility of cells representing various strategies of cell movement—specifically blebbing vs. lamellipodial migration. In the current study we constructed a unique experimental model which allowed for the investigation of electrotactic movement of cells of the same origin but representing different modes of cell migration: weakly adherent, spontaneously blebbing (BC) and lamellipodia forming (LC) WC256 cells. We report that both BC and LC sublines show robust cathodal migration in a physiological EF (1–3 V/cm). The directionality of cell movement was completely reversible upon reversing the field polarity. However, the full reversal of cell direction after the change of EF polarity was much faster in the case of BC (10 minutes) than LC cells (30 minutes). We also investigated the distinct requirements for Rac, Cdc42 and Rho pathways and intracellular Ca2+ in electrotaxis of WC256 sublines forming different types of cell protrusions. It was found that Rac1 is required for directional movement of LC to a much greater extent than for BC, but Cdc42 and RhoA are more crucial for BC than for LC cells. The inhibition of ROCK did not affect electrotaxis of LC in contrast to BC cells. The results also showed that intracellular Ca2+ is essential only for the electrotactic reaction of BC cells. Moreover, inhibition of MLCK and myosin II did not affect the electrotaxis of LC in contrast to BC cells. In conclusion, our results revealed that both lamellipodia and membrane blebs can efficiently drive electrotactic migration of WC 256 carcinosarcoma cells, however directional migration is mediated by different signalling pathways.

内源性电场（endogenous electric field, EF）可为伤口愈合、胚胎发育及癌症转移过程中的定向细胞迁移提供重要信号，但细胞趋电运动（electrotaxis）的机制仍不甚明确。此外，目前尚无研究探讨代表不同细胞运动策略——即胞膜出泡（blebbing）迁移与板状伪足（lamellipodial）迁移——的细胞在趋电运动能力上的差异。本研究构建了一种独特的实验模型，可用于探究同一起源但具有不同细胞迁移模式的细胞的趋电运动：弱粘附、自发出泡型（BC）以及形成板状伪足型（LC）WC256细胞。研究发现，BC与LC亚细胞系均可在生理强度电场（1–3 V/cm）中表现出显著的阴极定向迁移。当反转电场极性时，细胞运动的方向性可完全逆转；但电场极性改变后，BC细胞（10分钟）完成方向完全反转的速度远快于LC细胞（30分钟）。本研究还探究了Rac、Cdc42、Rho通路及细胞内钙离子（intracellular Ca2+）在形成不同细胞突起的WC256亚细胞系趋电运动中的独特必要条件。结果显示，Rac1对于LC细胞的定向运动的必要性远高于BC细胞，而Cdc42与RhoA对BC细胞的重要性则显著高于LC细胞。与BC细胞不同，ROCK的抑制并不会影响LC细胞的趋电运动。此外，细胞内钙离子仅对BC细胞的趋电反应至关重要。相较于BC细胞，MLCK与肌球蛋白II的抑制同样不会影响LC细胞的趋电运动。综上，本研究结果表明，板状伪足与膜出泡均可有效驱动WC256癌肉瘤细胞的趋电迁移，但定向迁移由不同的信号通路介导。