Strong EZH2 expression was associated with increased tumor cell proliferation in all four cancer types. Associations were also found between EZH2 and important clinicopathologic variables. EZH2 expression showed significant prognostic impact in melanoma, prostate, and endometrial carcinoma in univariate survival analyses, and revealed independent prognostic importance in carcinoma of the endometrium and prostate. CONCLUSION Our findings point at EZH2 as a novel and independent prognostic marker in endometrial cancer, and validate previous findings on prostate and breast cancer. Further, EZH2 expression was associated with features of aggressive cutaneous melanoma. The fact that EZH2 might identify increased tumor cell proliferation and aggressive subgroups in several cancers may be of practical interest because the polycomb group proteins have been suggested as candidates for targeted therapy. EZH2 expression should, therefore, be further examined as a possible predictive factor.

Metastasis underlies the majority of cancer-related deaths. Thus, furthering our understanding of the molecular mechanisms that enable tumor cell dissemination is a vital health issue. Epithelialto-mesenchymal transitions (EMTs) endow carcinoma cells with enhanced migratory and survival attributes that facilitate malignant progression. Characterization of EMT effectors is likely to yield new insights into metastasis and novel avenues for treatment. We show that the presence of the receptor tyrosine kinase Axl in primary breast cancers independently predicts strongly reduced overall patient survival, and that matched patient metastatic lesions show enhanced Axl expression. We demonstrate that Axl is strongly induced by EMT in immortalized mammary epithelial cells that establishes an autocrine signaling loop with its ligand, Gas6. Epiallelic RNA interference analysis in metastatic breast cancer cells delineated a distinct threshold of Axl expression for mesenchymal-like in vitro cell invasiveness and formation of tumors in foreign and tissue-engineered microenvironments in vivo. Importantly, in two different optical imagingbased experimental breast cancer models, Axl knockdown completely prevented the spread of highly metastatic breast carcinoma cells from the mammary gland to lymph nodes and several major organs and increased overall survival. These findings suggest that Axl represents a downstream effector of the tumor cell EMT that is required for breast cancer metastasis. Thus, the detection and targeted treatment of Axl-expressing tumors represents an important new therapeutic strategy for breast cancer.carcinoma | receptor tyrosine kinase | breast cancer

The polycomb group protein enhancer of zeste homologue 2 (EZH2) has been linked to invasive properties of aggressive breast cancer. In this report, tissue microarray analysis of 190 breast carcinomas from a nested case-control study shows that EZH2 is significantly associated with interval breast cancers. Further, a strong relationship was found with tumor cell proliferation (by Ki-67 expression), locally advanced disease, metastasis at presentation, markers of the basal epithelial phenotype (positivity for cytokeratin 5/6 or P-cadherin), and p53 status. EZH2 expression was also significantly associated with glomeruloid microvascular proliferation, an aggressive angiogenic phenotype. For prediction of aggressive disease (any event of locally advanced disease, lymph node spread, or distant spread), EZH2 was the only variable of significance in multivariate analysis, whereas no additional information was given by Ki-67. Although EZH2 expression was significant in univariate survival analysis, only tumor cell proliferation and lymph node status were significant in the final multivariate model. In conclusion, our findings indicate an important relationship not only between EZH2 and markers of tumor cell proliferation but also with aggressive disease. These findings might be practically important and relevant because the polycomb group proteins have recently been suggested as candidates for targeted therapy.Progression of breast cancer is a significant clinical problem and there is a need for novel treatment strategies. Although multiple prognostic factors have been reported, few markers, like c-erbB-2 status (Her2; ref. 1), have practical value as response predictors for targeted therapy (2). The enhancer of zeste homologue 2 (EZH2) is a member of the polycomb group of genes and has been involved in cell cycle regulation, and polycomb group proteins were recently suggested as candidates for targeted treatment (3). In human tumors, expression of EZH2 was first associated with hormone refractory and aggressive prostate cancer (4). In breast cancer, Kleer et al. (5) showed that EZH2 expression was increased in malignant tumors and promoted anchorage-independent and invasive growth in vitro, whereas proliferation was not significantly enhanced. EZH2 expression was further associated with increased tumor diameter, negative estrogen receptor (ER) and progesterone receptor (PR) status, and advanced stage of disease. Reduced patient survival was significantly predicted by EZH2 positivity in a subgroup of 194 cases. In a different study, Raaphorst et al. (6) found that EZH2 expression was associated with poorly differentiated and invasive breast cancers, whereas no clear relationship with proliferation was found. In this study, there was no prognostic effect of EZH2 expression.EZH2 is regulated by E2F transcription factors, which are liberated by retinoblastoma protein phosphorylation (7,8). Activated p53 down-regulates the EZH2 gene through repression of its promoter (9). Recently published cDNA microarray data i...