Although mutated forms of ras are not associated with the majority of breast cancers (<5%), there is considerable experimental evidence that hyperactive Ras can promote breast cancer growth and development. Therefore, we determined whether Ras and Ras-responsive signaling pathways were activated persistently in nine widely studied human breast cancer cell lines. Although only two of the lines harbor mutationally activated ras, we found that five of nine breast cancer cell lines showed elevated active Ras-GTP levels that may be due, in part, to HER2 activation. Unexpectedly, activation of two key Ras effector pathways, the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase and phosphatidylinositol 3-kinase/AKT signaling pathways, was not always associated with Ras activation. Ras activation also did not correlate with invasion or the expression of proteins associated with tumor cell invasion (estrogen receptor ␣ and cyclooxygenase 2). We then examined the role of Ras signaling in mediating resistance to matrix deprivationinduced apoptosis (anoikis). Surprisingly, we found that ERK and phosphatidylinositol 3-kinase/AKT activation did not have significant roles in conferring anoikis resistance. Taken together, these observations show that Ras signaling exhibits significant cell context variations and that other effector pathways may be important for Ras-mediated oncogenesis, as well as for anoikis resistance, in breast cancer. Additionally, because ERK and AKT activation are not strictly associated with Ras activation, pharmacological inhibitors of these two signaling pathways may not be the best approach for inhibition of aberrant Ras function in breast cancer treatment.

Increased expression of protease-activated receptor 1 (PAR1), a G protein-coupled receptor for thrombin, has previously been correlated with breast carcinoma cell invasion. PAR1 is irreversibly proteolytically activated, internalized, and sorted directly to lysosomes, a critical process for the termination of signaling. We determined that activated PAR1 trafficking is severely altered in metastatic breast carcinoma cells but not in nonmetastatic or normal breast epithelial cells. Consequently, the proteolytically activated receptor is not sorted to lysosomes and degraded. Altered trafficking of proteolytically activated PAR1 caused sustained activation of phosphoinositide hydrolysis and extracellular signal-regulated kinase signaling, even after thrombin withdrawal, and enhanced cellular invasion. Thus, our results reveal that a novel alteration in trafficking of activated PAR1 causes persistent signaling and, in addition to other processes and proteins, contributes to breast carcinoma cell invasion.The genetic changes that initiate tumor cell metastasis and invasion are unclear. The procoagulant activities of tumor cells and surrounding stromal cells that lead to thrombin generation and fibrin deposition appear to provide an important influence on tumor cell invasion and metastasis (3). Although a link between coagulation factors and tumor progression and metastasis has been firmly established, the molecular basis remains poorly understood (7, 26).Thrombin, the main effector protease of the coagulation cascade, is generated by the actions of tissue factor and other coagulation factors. The first description of thrombin-induced murine tumor cell metastasis was provided by Nierodzik and colleagues (23,24). Subsequent studies determined that tissue factor, like thrombin, is highly expressed in carcinoma cells and contributes to metastasis (20,21). In addition, the anticoagulants heparin and warfarin have been shown to significantly decrease experimentally induced pulmonary metastasis in vivo (37). A similar decrease in tumor cell metastasis in vivo was observed with hirudin, a specific inhibitor of thrombin (9). Fibrin, generated by the action of thrombin on fibrinogen, is a significant component of the tumor microenvironment and has been strongly associated with tumor progression and metastasis (7). A recent genetic study revealed that, in fibrinogendeficient mice, the development of both spontaneous and experimental lung metastases was substantially diminished (27). However, hirudin further diminished the metastatic potential of tumor cells in fibrinogen-deficient mice. Thus, while fibrinogen is one critical component of metastasis, thrombin appears to contribute to tumor cell dissemination through at least one fibrinogen-independent mechanism.

Background and Purpose. There is limited research on the effects of the number of exercises a person is told to perform on compliance and performance, as defined by cueing requirements, correct alignment, and quality of movement. Some studies of medication suggest that compliance decreases as the number of medications increases. The purpose of this study was to determine whether older adults comply and perform better (ie, requiring less cueing, exhibiting correct alignment, and exhibiting controlled, coordinated, and continuous movements) when they are asked to do 2, 5, or 8 exercises. Subjects. Subjects were 11 women and 4 men, aged 67 to 82 years (X̄=72.8), who were living independently in their communities. Methods. Subjects were randomly prescribed 2, 5, or 8 general strengthening home exercises. They were instructed on their exercises at an initial session and asked to record the number of repetitions performed each day in a self-report exercise log. At a return session 7 to 10 days later, subjects were scored on their performance of the prescribed exercises using a newly designed assessment tool. Results. The group that was prescribed 2 exercises performed better, as defined by their performance tool score, than the group that was prescribed 8 exercises. The group that was prescribed 5 exercises was not different from the groups that performed 2 or 8 exercises. No differences were found among groups regarding the self-report measurement of compliance. There was a moderate correlation between performance scores and the self-report percentage rates. Conclusion and Discussion. Subjects who were prescribed 2 exercises performed better than subjects who were prescribed 8 exercises. The question of an optimal number of exercises to prescribe to elderly people warrants further study.