Project description:Ovarian cancer is a nearly uniform lethal disease and its highly aggressive metastatic phenotype portends a poor prognosis. Lack of a well-controlled, relevant experimental model has been a major obstacle to identifying key molecules causing metastasis. Here we describe the creation of a new isogenic model of spontaneous human ovarian cancer metastasis exhibiting opposite phenotypes - highly metastatic (HM) and non-metastatic (NM) - both in vitro and in vivo. HM was unique in its ability to metastasize consistently to the peritoneum, mimicking the major dissemination route of human ovarian cancer. In contrast, NM failed to form detectable metastases although it was equally tumorigenic. Using comparative label-free quantitative LC-MS/MS, we identified b-catenin which we demonstrated for the first time a direct role in the pathogenesis of ovarian cancer metastasis. Our studies also revealed a previously unrecognized role of b-catenin in the downregulation of multiple microRNAs (miRNAs) through attenuating miRNA biogenesis by targeting Dicer, a key component of the microRNA processing machinery. One such downregulated miRNAs was miR-29s involved in epithelial-to-mesenchymal transition and subsequent stem cell traits. Silencing b-catenin or overexpressing Dicer or miR-29 mimics in HM significantly reduced the ability of these cells to migrate. B-catenin knockdown cells also failed to metastasize in an orthotopic model of ovarian cancer. Meta-analysis revealed an increase in CTNNB1 and a decrease in DICER1 expression levels in the high-risk group. These results uncover b-catenin as a critical player in promoting ovarian cancer aggressiveness and a new mechanism linking between b-catenin and miRNA downregulation underlying this process.
Project description:Deregulation of canonical Wnt/beta-catenin pathway is one of the earliest events in the pathogenesis of colon cancer. Mutations in APC or CTNNB1 (beta-catenin gene) are highly frequent in colon cancer and cause aberrant stabilization of b-catenin, which activates the transcription of Wnt target genes by binding to chromatin via the TCF/LEF transcription factors. Here we report an integrative analysis of genome-wide chromatin occupancy of b-catenin by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) and gene expression profiling by microarray analysis upon RNAi-mediated knockdown of beta-catenin in colon cancer cells (GSE53656). Immunoprecipitated samples from human colon cancer SW480 cells with antibodies against beta-catenin and control IgG respectively were used for ChIP-seq experiments.
Project description:Affymetrix GeneChip human gene 2.0 ST array analysis of SKOV-3 human ovarian cancer cells following siRNA knockdown of MAD2 or TLR4 compared to cells transfected with scrambled negative control siRNAs.
Project description:Deregulation of canonical Wnt/beta-catenin pathway is one of the earliest events in the pathogenesis of colon cancer. Mutations in APC or CTNNB1 (beta-catenin gene) are highly frequent in colon cancer and cause aberrant stabilization of b-catenin, which activates the transcription of Wnt target genes by binding to chromatin via the TCF/LEF transcription factors. Here we report an integrative analysis of genome-wide chromatin occupancy of b-catenin by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) and gene expression profiling by microarray analysis upon RNAi-mediated knockdown of beta-catenin in colon cancer cells (GSE53656).
Project description:Spheroids are 3D multi-cell aggregates formed in non-addherent culture conditions. In ovarian cancer (OC), they serve as a vehicle for cancer cell dissemination in the peritoneal cavity. We investigated genes and networks upregulated in three dimensional (3D) versus two-dimensional (2D) culture conditions by Affymetrix gene expression profiling and identified ALDH1A1, a cancer stem cell marker as being upregulated in OC spheroids. Network analysis confirmed ALDH1A1 upregulation in spheroids in direct connection with elements of the beta-catenin pathway. A parallel increase in the expression levels of beta-catenin and ALDH1A1 was demonstrated in spheroids vs. monolayers an in successive spheroid generations by using OC cell liness and primary OC cells. The percentage of Aldefluor positive cells was significantly higher in spheroids vs. monolayers in IGROV1, A2780, SKOV3, and primary OC cells. B-catenin knock-down decreased ALDH1A1 expression and chromatin immunoprecipitation demonstrated that beta-catenin directly binds to the ALDH1A1 promoter. Both siRNA mediated beta-catenin knock-down and a novel ALDH1A1 small molecule enzymatic inhibitor described here for the first time, decreased the number of OC spheroids (p<0.001) and cell viability. These data strongly support the role of beta-catenin regulated ALDH1A1 in the maintenance of OC spheroids and of a stem cell phenotype and propose new ALDH1A1 inhibitors targeting this cell population. Different gene profiles were observed in ovarian cancer spheroids versus ovarian cancer monolayers. Nine samples were analyzed in triplicate. Each group is a reference.