The ubiquitin E3 ligase WWP1 decreases CXCL12-mediated MDA231 breast cancer cell migration and bone metastasis

Abstract

Advanced breast cancers preferentially metastasize to bone where cells in the bone microenvironment produce factors that enhance breast cancer cell homing and growth. Expression of the ubiquitin E3 ligase WWP1 is increased in some breast cancers, but its role in bone metastasis has not been investigated. Here, we studied the effects of WWP1 and itch, its closest family member, on breast cancer bone metastasis. First, we immunostained a multi-tumor tissue microarray and a breast cancer tissue microarray and demonstrated that WWP1 and ITCH are expressed in some of breast cancer cases. We then knocked down WWP1 or itch in MDA-MB-231 breast cancer cells using shRNA and inoculated these cells and control cells into the left ventricle of athymic nude mice. Radiographs showed that mice given shWWP1 cells had more osteolytic lesions than mice given control MDA-MB-231 cells. Histologic analysis confirmed osteolysis and showed significantly increased tumor area in bone marrow of the mice. WWP1 knockdown did not affect cell growth, survival or osteoclastogenic potential, but markedly increased cell migration toward a CXCL12 gradient in vitro. Furthermore, WWP1 knockdown significantly reduced CXCL12-induced CXCR4 lysosomal trafficking and degradation. In contrast, itch knockdown had no effect on MDA-MB-231 cell bone metastasis. Taken together, these findings demonstrate that WWP1 negatively regulates cell migration to CXCL12 by limiting CXCR4 degradation to promote breast cancer metastasis to bone and highlight the potential utility of WWP1 as a prognostic indicator for breast cancer bone metastasis.

WW Domain Containing E3 Ubiquitin Protein Ligase 1 (WWP1) Negatively Regulates TLR4-Mediated TNF-α and IL-6 Production by Proteasomal Degradation of TNF Receptor Associated Factor 6 (TRAF6)

“…Lee et al (2013) reported that WWP1 interacted with AMPK and downregulated its expression through ubiquitin ligase activity in skeletal muscle [32]. Subik et al (2012) demonstrated that WWP1 functioned as an inhibitor of breast cancer metastasis to bone by negatively regulating CXCL 12-induced lysosomal degradation of CXCR4 [33]. In this study, we show for the first time that WWP1 plays an important role in TLR-mediated inflammation as an E3 ubiquitin ligase.…”

Functional Characterization of a WWP1/Tiul1 Tumor-derived Mutant Reveals a Paradigm of Its Constitutive Activation in Human Cancer

“…Indeed, many published studies have described various consequences of the WWP1-induced ubiquitination depending on the substrates, including proteasomal degradation, lysosomal degradation, subcellular redistribution, and transcriptional activity (5,22,23,30,31). Here, we found that WWP1 conjugated its polyubiquitination mainly through Lys-63 polyubiquitin chains, although we could clearly detect Lys-48-linked polyubiquitination.…”

Molecular functions of NEDD4 E3 ubiquitin ligases in cancer

“…WWP1 depletion led to increased cell migration towards a CXCL12 gradient, as well as reduced CXCL12-induced CXCR4 lysosomal trafficking and degradation, suggesting that WWP1 targets CXCR4 to lysosome-mediated destruction, although a more detailed mechanism remains to be elucidated. Mice inoculated with the breast cancer cells stably depleted of WWP1 showed more osteolytic lesions and significantly increased tumor area in bone marrow [138]. Overall, these findings suggest negative correlation between WWP1 level and bone metastasis in metastatic breast cancer, highlighting WWP1 as a potential biomarker and/or target of the disease.…”