ΔROCKII vs. 18.4±1.4 control, p<0.001). Similarly, both exhibited reduced motility compared with control cells (p<0.001) and lost their response to HGF. Importantly, no significant difference existed between knockdown and control cells in in vivo tumour growth. ROCKI was significantly higher in human mammary tumours than normal background tissue (2.9±1.1 vs. 0.29±0.13, p=0.023), although expression of ROCKII was fairly consistent in both (2050±646 vs. 2303±2079). ROCKI expression was greater in patients who died from breast cancer than in patients who remained disease free (11.6±7.1 vs. 1.95±0.95). Higher levels of ROCKI were associated with increased grade (0.95±0.73 grade-1; 2.11±1.72 grade-2; and 4.06±1.99 grade-3). Levels of ROCKI, but not ROCKII, were significantly correlated with overall survival of patients (p=0.004, Univariate analysis, median follow-up 120 month).These results show that ROCKI and possibly ROCKII are key factors in regulation of motility/invasion of breast cancer cells. This, together with significant correlation between ROCKI and poor outcome in clinical breast cancer, indicates that it is a potential target in human breast cancer.

Background: Development of metastasis in breast cancer is a multi-step process comprising changes in cytoskeletal structure and gene expression of tumour cells leading to changes in cell adhesion and motility. The Rho GTPase proteins, which function as guanine nucleotide regulated binary switches, govern a variety of cellular processes including cell motility and migration, changes in cell adhesion as well as actin cytoskeletal reorganisation and gene expression/transcription. One group of activators which regulate the Rho-GTPases is the guanine nucleotide exchange factors (GEFs), and this study looked at three such GEFs, Trio, Vav1 and TIAM-1. The purpose of this study was to investigate the expression of these GEFs, in human breast cancer and assess the affect on clinical outcome.

Purpose: The type II transmembrane serine proteases are cell surface proteolytic enzymes that mediate a diverse range of cellular functions, including tumor invasion and metastasis. Matriptase (matriptase-1) and matriptase-2 belong to the type II transmembrane serine protease family. Matriptase-1 is known to play a role in breast cancer progression, and elevated levels of matriptase-1 correlate with poor patient outcome. The role of matriptase-2 and its cellular function in cancer is unknown. This study aimed to provide new insights into the significance of matriptase-2 in cancer. Experimental Design: Matriptase-2 expression levels were assessed in a cohort of human breast cancer specimens (normal, n = 34; cancer, n = 95), in association with patient clinical variables, using both quantitative and qualitative analysis of the matriptase-2 transcript along with immunohistochemical techniques. Matriptase-2 was also experimentally overexpressed in the MDA-MB-231 human breast cancer cell line. The effects of matriptase-2 overexpression were examined through a series of in vitro and in vivo studies.Results: Here, we show that reduced matriptase-2 levels in breast cancer tissues correlate with an overall poor prognosis for the breast cancer patient. This study also reveals that matriptase-2 overexpression in breast cancer cells significantly suppressed tumorigenesis in CD1athymic mice (P = 0.000003). Furthermore, we report that matriptase-2 overexpression dramatically reduced the invasive (P = 0.0001) and migratory properties (P = 0.01) of the breast cancer cells. Conclusions: Matriptase-2 suppresses breast tumor development in vivo, displays prognostic value for breast cancer patients, inhibits both breast cancer cell invasion and motility in vitro, and may play a contrasting role to matriptase-1in breast cancer.Proteases, including metalloproteinases, are key to the destruction of the matrix barriers during the metastatic spread of cancer cells. In recent years, a new class of serine proteases, termed type II transmembrane serine proteases (TTSP), has emerged as another group of enzymes associated with tumor metastasis. TTSPs are characterized by a short NH 2 -terminal cytoplasmic tail, a membrane-spanning region, potential ligand binding domains, and a COOH-terminal serine protease domain (1). These proteolytic enzymes are ideally positioned to interact with other cell surface and soluble proteins and extracellular matrix components and have also been implicated in tumor progression. Members of the TTSP family include enteropeptidase/enterokinase, matriptase-1/membrane-type serine protease-1/TADG-15, hepsin/TMPRSS1, TMPRSS3/ TADG-12, corin, and DESC1 (2 -9). Matriptase-2 (also known as TMPRSS6) is a recently identified membrane-bound enzyme that belongs to the TTSP family (10).Studies suggest that TTSP expression is widely dysregulated during tumor growth and progression (11). Presently, the TTSP generating the most interest is matriptase-1. Matriptase-1 was originally identified in breast cancer cells (3) ...