helial-to-Mesenchymal Transition Promotes Tubulin yrosination and Microtentacles that Enhance

Downlo helial-to-mesenchymal transition (EMT) is associated with increased breast tumor metastasis; however, ecific mechanisms by which EMT promotes metastasis remain somewhat unclear. Despite the imporof cytoskeletal dynamics during both EMT and metastasis, very few current studies examine the cyton of detached and circulating tumor cells. Specific posttranslational α-tubulin modifications are critical herent cell motility and implicated in numerous pathologies, but also remain understudied in detached e report here that EMT induced through ectopic expression of Twist or Snail promotes α-tubulin deation and the formation of tubulin-based microtentacles in detached HMLEs. Mechanistically, EMT egulates the tubulin tyrosine ligase enzyme, resulting in an accumulation of detyrosinated α-tubulin ubulin), and increases microtentacles that penetrate endothelial layers to facilitate tumor cell reattachConfocal microscopy shows that microtentacles are capable of penetrating the junctions between helial cells. Suppression of endogenous Twist in metastatic human breast tumor cells is capable of ng both tubulin detyrosination and microtentacles. Clinical breast tumor samples display high concorbetween Glu-tubulin and Twist expression levels, emphasizing the coupling between EMT and tubulin sination in vivo. Coordinated elevation of Twist and Glu-tubulin at invasive tumor fronts, particularly ductal carcinoma in situ samples, establishes that EMT-induced tubulin detyrosination occurs at the t stages of tumor invasion. These data support a novel model where the EMT that occurs during tumor n downregulates tubulin tyrosine ligase, increasing α-tubulin detyrosination and promoting microteninvasio tacles that could enhance the reattachment of circulating tumor cells to the vascular endothelium during metastasis. Cancer Res; 70(20); 8127–37. ©2010 AACR.