ABSTRACT
Failure of currently used cytotoxic chemotherapy is one of the main reasons behind high mortality from metastatic high grade serous ovarian carcinoma. We found that high expression of a receptor for fractalkine (CX3CR1) significantly correlated with shorter survival of patients with serous ovarian carcinoma treated with cytotoxic DNA damage chemotherapies, and reduction of CX3CR1 expression resulted in sensitization to several DNA damaging modalities, including x-ray radiation and cisplatin. Here, we show that CX3CR1 plays a role in double-strand DNA break response and repair by regulating expression of RAD50 by a MYC-dependent mechanism. We demonstrate that downregulation of CX3CR1 alone and in a combination with irradiation affects peritoneal metastasis in an organ-specific manner; we show that CX3CR1 regulates lipid uptake which could control omental metastasis. This study identifies CX3CR1 as a novel potential target for sensitization of ovarian carcinoma to DNA damage therapies and reduction of peritoneal carcinomatosis.
ABSTRACT
CD44, a cell surface glycoprotein, has been increasingly implicated in the pathogenesis and progression of epithelial ovarian cancer, the deadliest gynecologic malignancy in women. Here, we review recent reports on the expression and function of CD44 in epithelial ovarian carcinoma. Further functional data for CD44 in peritoneal adhesion and metastatic progression and its association with stem cells is highlighted. Recent studies utilizing CD44 for therapeutic targeting are also discussed.
Subject(s)
Carcinoma/metabolism , Hyaluronan Receptors/metabolism , Ovarian Neoplasms/metabolism , Animals , Carcinoma/genetics , Carcinoma/therapy , Female , Humans , Hyaluronan Receptors/genetics , Neoplastic Stem Cells/metabolism , Ovarian Neoplasms/genetics , Ovarian Neoplasms/therapy , Protein Processing, Post-TranslationalABSTRACT
BACKGROUND: Epithelial ovarian carcinoma is a deadly disease characterized by overt peritoneal metastasis. Individual cells and multicellular aggregates, or spheroids, seed these metastases, both commonly found in ascites. Mechanisms that foster spheroid attachment to the peritoneal tissues preceding formation of secondary lesions are largely unknown. METHODS: Cell culture models of SKOV-3, OVCAR3, OVCAR4, Caov-3, IGROV-1, and A2780 were used. In this report the role of versican was examined in adhesion of EOC spheroids and cells to peritoneal mesothelial cell monolayers in vitro as well as in formation of peritoneal tumors using an in vivo xenograft mouse model. RESULTS: The data demonstrate that versican is instrumental in facilitating cell and spheroid adhesion to the mesothelial cell monolayers, as its reduction with specific shRNAs led to decreased adhesion. Furthermore, spheroids with reduced expression of versican failed to disaggregate to complete monolayers when seeded atop monolayers of peritoneal mesothelial cells. Failure of spheroids lacking versican to disaggregate as efficiently as controls could be attributed to a reduced cell migration that was observed in the absence of versican expression. Importantly, both spheroids and cells with reduced expression of versican demonstrated significantly impaired ability to generate peritoneal tumors when injected intraperitoneally into athymic nude mice. CONCLUSIONS: Taken together these data suggest that versican regulates the development of peritoneal metastasis originating from cells and spheroids.
Subject(s)
Neoplasms, Glandular and Epithelial/metabolism , Neoplasms, Glandular and Epithelial/pathology , Ovarian Neoplasms/metabolism , Ovarian Neoplasms/pathology , Versicans/metabolism , Animals , Carcinoma, Ovarian Epithelial , Cell Adhesion/genetics , Cell Line, Tumor , Cell Movement/genetics , Disease Models, Animal , Extracellular Matrix , Female , Gene Expression Regulation, Neoplastic , Humans , Immunophenotyping , Mice , Neoplasm Metastasis , Neoplasms, Glandular and Epithelial/genetics , Ovarian Neoplasms/genetics , Peritoneal Neoplasms/genetics , Peritoneal Neoplasms/pathology , Peritoneal Neoplasms/secondary , Peritoneum/metabolism , Peritoneum/pathology , RNA Interference , Spheroids, Cellular , Tumor Cells, Cultured , Up-Regulation , Versicans/geneticsABSTRACT
EZH2 catalyzes trimethylation of histone H3 lysine 27 (H3K27). Point mutations of EZH2 at Tyr641 and Ala677 occur in subpopulations of non-Hodgkin's lymphoma, where they drive H3K27 hypertrimethylation. Here we report the discovery of EPZ005687, a potent inhibitor of EZH2 (K(i) of 24 nM). EPZ005687 has greater than 500-fold selectivity against 15 other protein methyltransferases and has 50-fold selectivity against the closely related enzyme EZH1. The compound reduces H3K27 methylation in various lymphoma cells; this translates into apoptotic cell killing in heterozygous Tyr641 or Ala677 mutant cells, with minimal effects on the proliferation of wild-type cells. These data suggest that genetic alteration of EZH2 (for example, mutations at Tyr641 or Ala677) results in a critical dependency on enzymatic activity for proliferation (that is, the equivalent of oncogene addiction), thus portending the clinical use of EZH2 inhibitors for cancers in which EZH2 is genetically altered.
