Mesenchymal gene program-expressing ovarian cancer spheroids exhibit enhanced mesothelial clearance.
ABSTRACT: Metastatic dissemination of ovarian tumors involves the invasion of tumor cell clusters into the mesothelial cell lining of peritoneal cavity organs; however, the tumor-specific factors that allow ovarian cancer cells to spread are unclear. We used an in vitro assay that models the initial step of ovarian cancer metastasis, clearance of the mesothelial cell layer, to examine the clearance ability of a large panel of both established and primary ovarian tumor cells. Comparison of the gene and protein expression profiles of clearance-competent and clearance-incompetent cells revealed that mesenchymal genes are enriched in tumor populations that display strong clearance activity, while epithelial genes are enriched in those with weak or undetectable activity. Overexpression of transcription factors SNAI1, TWIST1, and ZEB1, which regulate the epithelial-to-mesenchymal transition (EMT), promoted mesothelial clearance in cell lines with weak activity, while knockdown of the EMT-regulatory transcription factors TWIST1 and ZEB1 attenuated mesothelial clearance in ovarian cancer cell lines with strong activity. These findings provide important insights into the mechanisms associated with metastatic progression of ovarian cancer and suggest that inhibiting pathways that drive mesenchymal programs may suppress tumor cell invasion of peritoneal tissues.
Project description:Dissemination of ovarian tumors involves the implantation of cancer spheroids into the mesothelial monolayer on the walls of peritoneal and pleural cavity organs. Biopsies of tumors attached to peritoneal organs show that mesothelial cells are not present under tumor masses. We have developed a live, image-based in vitro model in which interactions between tumor spheroids and mesothelial cells can be monitored in real time to provide spatial and temporal understanding of mesothelial clearance. Here we provide evidence that ovarian cancer spheroids utilize integrin- and talin- dependent activation of myosin and traction force to promote mesothelial cells displacement from underneath a tumor cell spheroid. These results suggest that ovarian tumor cell clusters gain access to the sub-mesothelial environment by exerting force on the mesothelial cells lining target organs, driving migration and clearance of the mesothelial cells.
Project description:To metastasize, carcinoma cells must attenuate cell-cell adhesion to disseminate into distant organs. A group of transcription factors, including Twist1, Snail1, Snail2, ZEB1, and ZEB2, have been shown to induce epithelial mesenchymal transition (EMT), thus promoting tumor dissemination. However, it is unknown whether these transcription factors function independently or coordinately to activate the EMT program. Here we report that direct induction of Snail2 is essential for Twist1 to induce EMT. Snail2 knockdown completely blocks the ability of Twist1 to suppress E-cadherin transcription. Twist1 binds to an evolutionarily conserved E-box on the proximate Snail2 promoter to induce its transcription. Snail2 induction is essential for Twist1-induced cell invasion and distant metastasis in mice. In human breast tumors, the expression of Twist1 and Snail2 is highly correlated. Together, our results show that Twist1 needs to induce Snail2 to suppress the epithelial branch of the EMT program and that Twist1 and Snail2 act together to promote EMT and tumor metastasis.
Project description:Basic helix-loop-helix transcription factor Twist1 is a master regulator of Epithelial-Mesenchymal Transition (EMT), a cellular program implicated in different stages of development as well as metastatic dissemination of carcinomas. Here, we show that Twist1 requires TGF-beta type-I receptor (TGFBR1)-activation to bind an enhancer region of downstream effector ZEB1, thereby inducing ZEB1 transcription and EMT. When TGFBR1-phosphorylation is inhibited, Twist1 generates a distinct cell state characterized by collective invasion, simultaneous proliferation and expression of endothelial markers. By contrast, TGFBR1-activation directs Twist1 to induce stable mesenchymal transdifferentiation through EMT, thereby generating cells that display single-cell invasion, but lose their proliferative capacity. In conclusion, preventing Twist1-induced EMT by inhibiting TGF?-signaling does not generally block acquisition of invasion, but switches mode from single-cell/non-proliferative to collective/proliferative. Together, these data reveal that transient Twist1-activation induces distinct cell states depending on signaling context and caution against the use of TGF?-inhibitors as a therapeutic strategy to target invasiveness.
Project description:Transcription factors regulating the epithelial-to-mesenchymal transition (EMT) program contribute to carcinogenesis and metastasis in many tumors, including cutaneous melanoma. However, little is known about the role of EMT factors in the growth and metastatic dissemination of uveal melanoma cells. Here, we analyzed the expression and functions of the EMT factors ZEB1, Twist1, and Snail1 in uveal melanoma cell lines and primary tumors.ZEB1, Twist1, and Snail1 mRNA levels were measured using qPCR in five uveal melanoma cell lines and in 30 primary tumors. Gene expression was used to determine class 1 and class 2 signatures in the primary tumors. Short hairpin RNA was used to downregulate the expressions of the EMT factors; then, growth and transwell invasion assays were performed.ZEB1, Twist1, and Snail1 were expressed in all five uveal melanoma lines, with ZEB1 having the highest protein levels. ZEB1 mRNA was significantly elevated in highly metastatic class 2 primary tumors for which survival data were not available, whereas a high gene expression of Twist1 was associated with a worse prognosis in a separate tumor cohort analyzed by expression profiling. The genetic downregulation of ZEB1 in OCM1, OMM1, and 92.1 resulted in a more than 50% reduction in invasion, but only suppressed growth in OMM1 cells. Suppression of Twist1 in Mel290 and OMM1 reduced growth and invasion by more than 50%. The downregulation of Snail1 in the 92.1 cell line reduced invasion by 50%, but did not interfere with growth.The downregulation of ZEB1, Twist1, and Snail1 reduces the invasive properties of uveal melanoma cells, and the elevated mRNA levels of ZEB1 and Twist1 are associated with a more aggressive clinical phenotype in uveal melanoma samples. Therefore, these factors could represent new therapeutic targets in patients with ocular melanoma.
Project description:Epithelial ovarian cancer (EOC) metastasis occurs by exfoliation of cells and multicellular aggregates (MCAs) from the tumor into the peritoneal cavity, adhesion to and retraction of peritoneal mesothelial cells and subsequent anchoring. Elevated levels of lysophosphatidic acid (LPA) have been linked to aberrant cell proliferation, oncogenesis, and metastasis. LPA disrupts junctional integrity and epithelial cohesion in vitro however, the fate of free-floating cells/MCAs and the response of host peritoneal tissues to LPA remain unclear. EOC MCAs displayed significant LPA-induced changes in surface ultrastructure with the loss of cell surface protrusions and poor aggregation, resulting in increased dissemination of small clusters compared to untreated control MCAs. LPA also diminished the adhesive capacity of EOC single cells and MCAs to murine peritoneal explants and impaired MCA survival and mesothelial clearance competence. Peritoneal tissues from healthy mice injected with LPA exhibited enhanced mesothelial surface microvilli. Ultrastructural alterations were associated with restricted peritoneal susceptibility to metastatic colonization by single cells as well as epithelial-type MCAs. The functional consequence is an LPA-induced dissemination of small mesenchymal-type clusters, promoting a miliary mode of peritoneal seeding that complicates surgical removal and is associated with worse prognosis.
Project description:The mesenchymal gene program has been shown to promote the metastatic progression of ovarian cancer; however, specific proteins induced by this program that lead to these metastatic behaviors have not been identified. Using patient derived tumor cells and established human ovarian tumor cell lines, we find that the Epithelial-to-Mesenchymal Transition inducing factor TWIST1 drives expression of discoidin domain receptor 2 (DDR2), a receptor tyrosine kinase (RTK) that recognizes fibrillar collagen as ligand. The expression and action of DDR2 was critical for mesothelial cell clearance, invasion and migration in ovarian tumor cells. It does so, in part, by upregulating expression and activity of matrix remodeling enzymes that lead to increased cleavage of fibronectin and spreading of tumor cells. Additionally, DDR2 stabilizes SNAIL1, allowing for sustained mesenchymal phenotype. In patient derived ovarian cancer specimens, DDR2 expression correlated with enhanced invasiveness. DDR2 expression was associated with advanced stage ovarian tumors and metastases. In vivo studies demonstrated that the presence of DDR2 is critical for ovarian cancer metastasis. These findings indicate that the collagen receptor DDR2 is critical for multiple steps of ovarian cancer progression to metastasis, and thus, identifies DDR2 as a potential new target for the treatment of metastatic ovarian cancer.
Project description:Emodin has a direct inhibitory effect on the growth and metastasis of a variety of malignant tumor cells. MicroRNA?1271 (miR?1271) has an extensive tumor?suppression effect by inhibiting epithelial mesenchymal transition (EMT) in tumor cells and induces tumor cell apoptosis. Proceeding with the EMT regulatory mechanism of pancreatic carcinoma, the present study aimed to examine the inhibitory effect of miR?1271 and emodin against invasion and metastasis of pancreatic carcinoma. The expression of EMT?related markers (E?cadherin, ZEB1 and TWIST1) was analyzed by western blotting. mRNA levels of miR?1271, E?cadherin, ZEB1 and TWIST1 in pancreatic tumor cells (SW1990) were measured through reverse transcription?quantitative polymerase chain reaction and cell invasiveness was detected using Transwell assays. In addition, a liver metastatic model was established with an implantation of pancreatic tumor tissue into the spleens of nude mice to study the effect of emodin on pancreatic cancer liver metastasis. In the present study, it was demonstrated that miR?1271 significantly decreased in pancreatic cancer cells and tissues. Twist1 may be a target gene of miR?1271. Emodin could inhibit the proliferation ability of pancreatic cancer cells and increased miR?1271 expression level. Further, we found that miR?1271 significantly inhibited SW1990 cell EMT and invasive ability. We also provided the evidence that emodin inhibited SW1990 cell EMT by raising the level of miR?1271. Moreover, the in vivo experiments have verified the inhibiting effect of emodin against liver metastasis of pancreatic cancer. The data in the present study indicated that emodin inhibited pancreatic cancer EMT and invasion by increasing the content of miR?1271.
Project description:Ascitic multicellular aggregates (MCAs) promote peritoneal metastasis of ovarian cancer. The aim of the present study was to elucidate the role of cancer?associated fibroblasts (CAFs) in MCA formation and metastasis in patients with high?grade serous ovarian cancer (HGSOC). Immunohistochemistry was used to identify the cell phenotypes and the presence of CAFs in ascitic MCAs. The role of CAFs in tumor?cell MCA formation was assessed by co?culture in suspension. Primary ascitic tumor cells and omental CAFs were used to generate ex vivo MCAs in hanging drops, and the invasiveness of MCAs was evaluated by mesothelial clearance and adhesion assays in vitro and in vivo. MCAs containing CAFs and tumor cells were identified in the ascitic fluid. CAFs facilitated tumor cell aggregation and compaction to form MCAs, and enhanced the mesothelial clearance and adhesion abilities of tumor?cell MCAs. These findings suggest that ascitic CAFs promote peritoneal metastasis by forming heterotypic aggregates with tumor cells, and that they may serve as potential targets for the treatment of HGSOC.
Project description:Lymph node metastasis is an important prognosis factor in non-small cell lung cancer (NSCLC) patients. The aim of this study was to investigate the role of epithelial to mesenchymal transition (EMT) in lymph node progression in the early stages of NSCLC. We studied a retrospective cohort of 160 consecutive surgically treated NSCLC patients with available frozen tumor samples for expression of EMT markers (CDH1, CTNNB1, CDH2, and VIMENTIN), inducers (TGFB1, c-MET, and CAIX), and transcription factors (EMT-TF: SNAI1, SNAI2, ZEB1, TWIST1, and TWIST2). Partial EMT was more frequent in N1-2 (N+) vs N0 patients (P < .01). TGFB1 (P = .02) as well as SNAI2 (P < .01) and TWIST1 (P = .04) were the most differentially expressed genes in N+ tumors. In this group, ZEB1 was correlated with all EMT inducers and other EMT-TFs were overexpressed depending on the inducers. CAIX was an independent prognostic factor for overall survival (IC 95% HR: 1.10-5.14, P = .03). Partial EMT is involved in lymph node progression of NSCLC patients and depends on the TGF? pathway. EMT-TFs are differentially expressed depending on EMT inducers. CAIX might be a relevant prognostic marker in early stage NSCLC.
Project description:The peculiar localization of body cavity lymphomas implies a specific contribution of the intracavitary microenvironment to the pathogenesis of these tumors. In this study, primary effusion lymphoma (PEL) was used as a model of body cavity lymphoma to investigate the role of mesothelial cells, which line the serous cavities, in lymphoma progression. The crosstalk between mesothelial and lymphomatous cells was studied in cocultures of primary human mesothelial cells (HMC) with PEL cells and a xenograft mouse model of peritoneal PEL. PEL cells were found to induce type 2 epithelial-mesenchymal transition (EMT) in HMC, which converted into a myofibroblastic phenotype characterized by loss of epithelial markers (pan cytokeratin and E-cadherin), expression of EMT-associated transcriptional repressors (Snail1, Slug, Zeb1, Sip1), and acquisition of ?-smooth muscle actin (?-SMA), a mesenchymal protein. A progressive thickening of serosal membranes was observed in vivo, accompanied by loss of cytokeratin staining and appearance of ?-SMA-expressing cells, confirming that fibrosis occurred during intracavitary PEL development. On the other hand, HMC were found to modulate PEL cell turnover in vitro, increasing their resistance to apoptosis and proliferation. This supportive activity on PEL cells was retained after transdifferentiation, and was impaired by interferon-?2 b treatment. On the whole, our results indicate that PEL cells induce type 2 EMT in HMC, which support PEL cell growth and survival, providing a milieu favorable to lymphoma progression. Our findings provide new clues into the mechanisms involved in lymphoma progression and may indicate new targets for effective treatment of malignant effusions growing in body cavities.