Increased expression of the proteoglycan, versican is strongly associated with poor outcome for many different cancers. Depending on the cancer type, versican is expressed by either the cancer cells themselves or by stromal cells surrounding the tumor. Versican plays diverse roles in cell adhesion, proliferation, migration and angiogenesis, all features of invasion and metastasis. These wide ranging functions have been attributed to the central glycosaminoglycan-binding region of versican, and to the N-(G1) and C-(G3) terminal globular domains which collectively interact with a large number of extracellular matrix and cell surface structural components. Here we review the recently identified mechanisms responsible for the regulation of versican expression and the biological roles that versican plays in cancer invasion and metastasis. The regulation of versican expression may represent one mechanism whereby cancer cells alter their surrounding microenvironment to facilitate the malignant growth and invasion of several tumor types. A greater understanding of the regulation of versican expression may contribute to the development of therapeutic methods to inhibit versican function and tumor invasion.

The majority of human melanomas harbor activating mutations in either the BRAF or NRAS gene. To date, the role of oncogenic NRAS in melanoma remains poorly defined and no current therapies are directed at specifically suppressing oncogenic NRAS in human melanoma tumors. The aim of our study, therefore, was to investigate the effects of suppressing oncogenic NRAS in human melanoma cell lines in vitro. Using both small interfering RNAand plasmid based-RNA interference techniques, oncogenic NRAS was specifically suppressed in 2 human melanoma cell lines, 224 and BL, which harbor a codon 61 CAA (glutamine) to CGA (arginine) NRAS mutation. Suppression of oncogenic NRAS in these cell lines resulted in increased apoptosis. Furthermore, in 224 cells we demonstrated decreased phosphorylation of extracellular signal-regulated kinase (ERK) and Akt, and reduced expression of NF-kB and cyclin D1 in the N-Ras signaling pathway. In contrast, RNA interference directed at wild-type (WT) NRAS had no significant effect on apoptosis of 224 cells or 2 human melanoma cell lines (A375 and 397) containing WT NRAS but a codon 600 GTG (valine) to GAG (glutamate) mutation in BRAF. These data suggest that oncogenic NRAS is important for avoidance of apoptosis in melanomas that harbor the codon 61 NRAS mutation and emphasizes oncogenic NRAS as a therapeutic target in patients with tumors that harbor this mutation. ' 2005 Wiley-Liss, Inc.Key words: RNAi; melanoma; Ras; signal transduction; apoptosis Activation of Ras is a common molecular event in the etiology of human cancer. 1 The Ras proteins H-, K-and N-Ras are central regulators of cellular signal transduction processes leading to cell growth and differentiation. In the resting cell, Ras proteins are in the guanosine diphosphate (GDP)-bound inactive state. However, in response to receptor protein tyrosine kinases or other growth factor-dependent stimuli, these Ras proteins become activated by binding guanosine triphosphate (GTP). 2,3 Oncogenic mutations in codons 12, 13 and 61 of RAS genes prevent GTP hydrolysis, resulting in constitutively active Ras proteins. Such mutations that change the protooncogene RAS to an active oncogene are found in approximately 30 to 50% of human tumors. [4][5][6][7][8] Ras has also been demonstrated to be important for both the genesis and maintenance of melanoma. For instance, in a doxycycline-inducible H-Ras V12G mouse melanoma model, withdrawal of doxycycline was demonstrated to result in histological regression of primary and implanted tumors accompanied by marked apoptosis of melanoma cells. 9 Studies on melanoma tumors have confirmed that oncogenic activation of NRAS constitutes the predominant RAS alteration in cutaneous melanoma, with NRAS codon 61 mutations being the most common alterations and codon 12 and 13 mutations being less frequent. 6,7,10,11 In sporadic melanoma cases, the frequency of NRAS alterations reported varies in different studies. [12][13][14] In a study performed by our group, 28% of primary melanomas and 37% of metastatic tumo...

Purpose: Consensus is lacking regarding the androgen receptor (AR) as a prognostic marker in breast cancer. The objectives of this study were to comprehensively review the literature on AR prognostication and determine optimal criteria for AR as an independent predictor of breast cancer survival.Experimental Design: AR positivity was assessed by immunostaining in two clinically validated primary breast cancer cohorts [training cohort, n ¼ 219; validation cohort, n ¼ 418; 77% and 79% estrogen receptor alpha (ERa) positive, respectively]. The optimal AR cut-point was determined by ROC analysis in the training cohort and applied to both cohorts.Results: AR was an independent prognostic marker of breast cancer outcome in 22 of 46 (48%) previous studies that performed multivariate analyses. Most studies used cut-points of 1% or 10% nuclear positivity. Herein, neither 1% nor 10% cut-points were robustly prognostic. ROC analysis revealed that a higher AR cut-point (78% positivity) provided optimal sensitivity and specificity to predict breast cancer survival in the training (HR, 0.41; P ¼ 0.015) and validation (HR, 0.50; P ¼ 0.014) cohorts. Tenfold cross-validation confirmed the robustness of this AR cut-point. Patients with ERa-positive tumors and AR positivity !78% had the best survival in both cohorts (P < 0.0001). Among the combined ERa-positive cases, those with comparable or higher levels of AR (AR:ERa-positivity ratio >0.87) had the best outcomes (P < 0.0001).Conclusions: This study defines an optimal AR cut-point to reliably predict breast cancer survival. Testing this cut-point in prospective cohorts is warranted for implementation of AR as a prognostic factor in the clinical management of breast cancer.