N-WASP is a putative tumour suppressor in breast cancer cells, in vitro and in vivo, and is associated with clinical outcome in patients with breast cancer

Abstract

N-WASP is a key regulator of cell migration and actin polymerisation. We examined the correlation of N-WASP, with human breast cancer, in vitro, in vivo and in clinical breast cancer tissue. Immunohistochemical study of frozen sectioned human breast mammary tissues (n=124) revealed that mammary epithelial cells stained positively for N-WASP and that cancer cells in tumour tissues stained very weakly. Quantitative RT-PCR revealed that breast cancer tissues had significantly lower levels of N-WASP compared with normal background mammary tissues (0.83+/-0.3 vs 13.6+/-13, P=0.03). Although no significantly correlation was found with tumour grade and TNM staging, lower levels of transcript were seen to correlate with clinical outcome following a ten year follow up. Thus tumours from patients with predicted poor prognosis had significantly lower levels than from those with good prognosis (0.098+/-0.14 vs 1.14+/-0.56, P=0.05). Patients with metastatic disease/died of breast cancer had significantly lower levels of N-WASP compared to those remaining disease free (0.04+/-0.02 and 0.47+/-0.3, vs 0.79+/-0.44, P=0.01 and P<0.05 respectively). During in vitro experiments, MDA-MB-231 cells stably transfected with N-WASP (MDA-MB-231(WASP+)) exhibited a significantly reduced in vitro invasiveness and motility compared with control and wild type cells (P<0.0001), had increased adhesiveness (P=0.05) and moreover MDA-MB-231(WASP+ )exhibited reduced in vivo growth (P=0.002). The motogen HGF (50 ng/ml) caused a relocation of N-WASP to the cell periphery in a temporal and spatial response. It is concluded that N-WASP, a member of the N-WASP family may act as a tumour progression suppressor in human breast cancer and may therefore have significant clinical value in this condition.

N-WASP-mediated invadopodium formation is involved in intravasation and lung metastasis of mammary tumors

“…It has been reported that lower levels of expression of N-WASP in whole breast tumor tissue is correlated with poor outcome, using disease-free survival as the end point (Martin et al, 2008). However, this study did not evaluate the behavior of the migratory and disseminating population of breast cancer cells in the primary tumor or the requirement of N-WASP for these phenotypes in vivo.…”

“…A previous study has shown that the overexpression of N-WASP or DN N-WASP does not affect cell-cell junctions in epithelial cells (Yamaguchi et al, 2002) and that DN N-WASP overexpression had little effect on random cell migration in vitro, indicating that N-WASP is not involved in general cell locomotion. A different study (Martin et al, 2008) reported that N-WASP overexpression increased adhesiveness in breast cancer cells and reduced tumor growth rate.…”

Evaluation of the expression of stem cell markers in human breast cancer reveals a correlation with clinical progression and metastatic disease in ductal carcinoma

“…Sections were counterstained in Mayer's haematoxylin for 1 min, dehydrated, cleared and mounted in DPX. Following this, the sections were analyzed for staining intensity as previously described (9,10).…”

Neural Wiskott-Aldrich syndrome protein modulates Wnt signaling and is required for hair follicle cycling in mice

“…It was recently revealed that an absence or decrease in WASP family protein expression in T cells has been associated with a decrease in cell proliferation (33). In contrast, N-WASP has been implicated as a tumor suppressor in breast epithe- lium (45). One can speculate that N-WASP, via its apparent effect on actin cytoskeleton dynamics, regulates keratinocyte adhesion to the extracellular matrix, a process known to control keratinocyte growth (37).…”