Journal of Biological Chemistry
Volume 285, Issue 47, 19 November 2010, Pages 36721-36735
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Signal Transduction
Hyaluronan-CD44 Interaction Promotes c-Src-mediated Twist Signaling, MicroRNA-10b Expression, and RhoA/RhoC Up-regulation, Leading to Rho-kinase-associated Cytoskeleton Activation and Breast Tumor Cell Invasion*

https://doi.org/10.1074/jbc.M110.162305Get rights and content
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Dysregulation of microRNAs is observed in many cancers, including breast cancer. In particular, miR-10b appears to play an important role in tumor cell invasion and breast cancer progression. In this study, we investigated hyaluronan (HA)-induced CD44 (a primary HA receptor) interaction with c-Src kinase and the transcriptional factor, Twist, in breast tumor cells (MDA-MB-231 cells). Our results indicate that HA binding to CD44 promotes c-Src kinase activation, which, in turn, increases Twist phosphorylation, leading to the nuclear translocation of Twist and transcriptional activation. Further analyses reveal that miR-10b is controlled by an upstream promoter containing the Twist binding site(s), whereas ChIP assays demonstrate that stimulation of miR-10b expression by HA/CD44-activated c-Src is Twist-dependent in breast tumor cells. This process results in the reduction of a tumor suppressor protein (HOXD10), RhoA/RhoC up-regulation, Rho-kinase (ROK) activation, and breast tumor cell invasion. Treatment of MDA-MB-231 cells with PP2 (a c-Src inhibitor) or Twist-specific siRNAs effectively blocks HA-mediated Twist signaling events, abrogates miR-10b production, and increases HOXD10 expression. Subsequently, this c-Src/Twist signaling inhibition causes down-regulation of RhoA/RhoC expression and impairment of ROK-regulated cytoskeleton function (e.g. tumor cell invasion). To further evaluate the role of miR-10b in RhoGTPase signaling, MDA-MB-231 cells were also transfected with a specific anti-miR-10b inhibitor in order to silence miR-10b expression and block its target functions. Our results demonstrate that anti-miR-10b inhibitor not only enhances HOXD10 expression but also abrogates HA/CD44-mediated tumor cell behaviors in breast tumor cells. Taken together, these findings indicate that the HA-induced CD44 interaction with c-Src-activated Twist plays a pivotal role in miR-10b production, leading to the down-regulation of tumor suppressor protein (HOXD10), RhoGTPase-ROK activation, and tumor cell invasion. All of these events are critical prerequisite steps for the acquisition of metastatic properties by human breast cancer cells.

Breast Cancer
Cell Surface Receptor
Hyaluronate
MicroRNA
Signal Transduction
Cytoskeleton

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*

This work was supported, in whole or in part, by National Institutes of Health Grants R01 CA66163, R01 CA78633, and P01 AR39448. This work was also supported by a Veterans Affairs merit review grant.