Search

Uncontrolled metastasis significantly contributes to high lethality of patients suffering from ovarian cancer. To date, the detailed molecular mechanisms which account for ovarian tumor cell spreading and metastasis remain largely unknown. In a recent study, we have demonstrated that aberrantly high expression of the non-receptor tyrosine kinase FER is responsible for ovarian tumor cell metastasis both in vitro and in vivo. Mechanistically, we indentified Hepatocyte Growth Factor Receptor HGFR/MET as a novel substrate of FER, and through which the kinase FER modulates ovarian cancer cell motility and invasiveness in a ligand-independent manner. We also observed aberrantly high expression of PAK1 kinase in cancer cells, and RNAi-mediated knockdown of FER kinase inactivated the RAC1-PAK1 signaling pathway and decreased metastatic potential of CAOV4 ovarian cancer cells. Overall, our study revealed a previously uncharacterized, pro-metastatic role of the kinase FER in ovarian cancer through the MET-RAC1-PAK1 pathway. Further efforts are essential to investigating beneficial outcomes towards targeting the RAC1-PAK1 signaling pathway in reducing metastatic burden of this deadly disease. [ABSTRACT FROM AUTHOR]

Metastasis is the leading cause of high ovarian-cancer-related mortality worldwide. Three major processes constitute the whole metastatic cascade: invasion, intravasation, and extravasation. Tumor cells often reprogram their metabolism to gain advantages in proliferation and survival. However, whether and how those metabolic alterations contribute to the invasiveness of tumor cells has yet to be fully understood. Here we performed a genome-wide CRISPR-Cas9 screening to identify genes participating in tumor cell dissemination and revealed that PTGES3 acts as an invasion suppressor in ovarian cancer. Mechanistically, PTGES3 binds to phosphofructokinase, liver type (PFKL) and generates a local source of prostaglandin E2 (PGE2) to allosterically inhibit the enzymatic activity of PFKL. Repressed PFKL leads to downgraded glycolysis and the subsequent TCA cycle for glucose metabolism. However, ovarian cancer suppresses the expression of PTGES3 and disrupts the PTGES3-PGE2-PFKL inhibitory axis, leading to hyperactivation of glucose oxidation, eventually facilitating ovarian cancer cell motility and invasiveness. [Display omitted] • CRISPR-Cas9 screening identifies PTGES3 as an invasion suppressor in ovarian cancer • PTGES3 is associated with the glycolytic rate-limiting enzyme PFKL • PTGES3-mediated prostaglandin E2 production elicits allosteric inhibition of PFKL • Loss of PTGES3 facilitates the epithelial-mesenchymal transition Chen et al. identify a tumor-suppressive gene, PTGES3 , and a tumor-suppressive metabolite, PGE2, in ovarian cancer cells, which behave as a "glycolytic rheostat." They elucidate the mechanism of how PGE2 allosterically inhibits the activity of the glycolytic rate-limiting enzyme PFKL, providing a potential molecular vulnerability for treating ovarian cancer metastasis. [ABSTRACT FROM AUTHOR]

Although DNA encodes the molecular instructions that underlie the control of cell function, it is the proteins that are primarily responsible for implementing those instructions. Therefore quantitative analyses of the proteome would be expected to yield insights into important candidates for the detection and treatment of disease. We present an iTRAQ (isobaric tag for relative and absolute quantification)-based proteomic analysis of ten ovarian cancer cell lines and two normal ovarian surface epithelial cell lines. We profiled the abundance of 2659 cellular proteins of which 1273 were common to all 12 cell lines. Of the 1273, 75 proteins exhibited elevated expression and 164 proteins had diminished expression in the cancerous cells compared with the normal cell lines. The iTRAQ expression profiles allowed us to segregate cell lines based upon sensitivity and resistance to carboplatin. Importantly, we observed no substantial correlation between protein abundance and RNA expression or epigenetic DNA methylation data. Furthermore, we could not discriminate between sensitivity and resistance to carboplatin on the basis of RNA expression and DNA methylation data alone. The present study illustrates the importance of proteomics-based discovery for defining the basis for the carboplatin response in ovarian cancer and highlights candidate proteins, particularly involved in cellular redox regulation, homologous recombination and DNA damage repair, which otherwise could not have been predicted from whole genome and expression data sources alone. [ABSTRACT FROM AUTHOR]

A critical aspect of understanding the regulation of signal transduction is not only to identify the protein-protein interactions that govern assembly of signaling pathways, but also to understand how those pathways are regulated in time and space. In this report, we have applied both gain-of-function and loss-of-function analyses to assess the role of the non-receptor protein tyrosine kinase FER in activation of the HGF Receptor protein tyrosine kinase MET. Overexpression of FER led to direct phosphorylation of several signaling sites in MET, including Tyr1349, but not the activation loop residues Tyr1234/5; in contrast, suppression of FER by RNAi revealed that phosphorylation of both a C-terminal signaling site (Tyr1349) and the activation loop (Tyr1234/5) were influenced by the function of this kinase. Adaptin β, a component of the adaptor protein complex 2 (AP-2) that links clathrin to receptors in coated vesicles, was recruited to MET following FER-mediated phosphorylation. Furthermore, we provide evidence to support a role of FER in maintaining plasma membrane distribution of MET and thereby delaying protein-tyrosine phosphatase PTP1B-mediated inactivation of the receptor. Simultaneous up-regulation of FER and down-regulation of PTP1B observed in ovarian carcinoma-derived cell lines would be expected to contribute to persistent activation of HGF-MET signaling, suggesting that targeting of both FER and MET may be an effective strategy for therapeutic intervention in ovarian cancer. [ABSTRACT FROM AUTHOR]