Solitary fibrous tumor (SFT) is a rare tumor of mesenchymal origin that account for less than 2% of all soft tissue masses. Initially identified in the pleura, SFT has been identified in multiple anatomic locations and can arise anywhere in the body. The varying histologic features along with non-specific means of identification have led SFT to be associated with several different names. Over the last several decades, sustained advances through research and technology have led to more reliable methods for differentiating this distinct soft tissue tumor. Advances specifically in immunohistochemistry and molecular diagnostics have identified CD34 as the most consistent marker in SFT, however even this lacks specificity to conclusively narrow down the broad differential for exact identification. More recently the discovery of the NAB2-STAT6 fusion gene has led to more precise diagnosis of SFT. Like many other soft tissue tumors, surgical management is the mainstay of treatment for SFT with emphasis on obtaining tumor-negative margins. Radiation therapy and chemotherapy regimens have not demonstrated global effectiveness, and thus no standardized treatments have been identified. Given the rarity of SFT and current supportive evidence for therapies, management should be focused on tumor extirpation. Nonetheless, individualized therapy, determined within a multidisciplinary setting should be considered.

Objective Genomic studies of ovarian cancer (OC) cell lines frequently used in research revealed that these cells do not fully represent high-grade serous ovarian cancer (HGSOC), the most common OC histologic type. However, OC lines that appear to genomically resemble HGSOC have not been extensively used and their growth characteristics in murine xenografts are essentially unknown. Methods To better understand growth patterns and characteristics of HGSOC cell lines in vivo, CAOV3, COV362, KURAMOCHI, NIH-OVCAR3, OVCAR4, OVCAR5, OVCAR8, OVSAHO, OVKATE, SNU119, UWB1.289 cells were assessed for tumor formation in nude mice. Cells were injected intraperitoneally (i.p.) or subcutaneously (s.c.) in female athymic nude mice and allowed to grow (maximum of 90 days) and tumor formation was analyzed. All tumors were sectioned and assessed using H&E staining and immunohistochemistry for p53, PAX8 and WT1 expression. Results Six lines (OVCAR3, OVCAR4, OVCAR5, OVCAR8, CAOV3, and OVSAHO) formed i.p xenografts with HGSOC histology. OVKATE and COV362 formed s.c. tumors only. Rapid tumor formation was observed for OVCAR3, OVCAR5 and OVCAR8, but only OVCAR8 reliably formed ascites. Tumors derived from OVCAR3, OVCAR4, and OVKATE displayed papillary features. Of the 11 lines examined, three (Kuramochi, SNU119 and UWB1.289) were non-tumorigenic. Conclusions Our findings help further define which HGSOC cell models reliably generate tumors and/or ascites, critical information for preclinical drug development, validating in vitro findings, imaging and prevention studies by the OC research community.

Tissue transglutaminase (TG2) is involved in Ca 2+ -dependent aggregation and polymerization of proteins. We previously reported that TG2 mRNA is up-regulated in epithelial ovarian cancer (EOC) cells compared with normal ovarian epithelium. Here, we show overexpression of the TG2 protein in ovarian cancer cells and tumors and its secretion in ascites fluid and define its role in EOC. By stable knockdown and overexpression, we show that TG2 enhances EOC cell adhesion to fibronectin and directional cell migration. This phenotype is preserved in vivo, where the pattern of tumor dissemination in the peritoneal space is dependent on TG2 expression levels.

Women with high-grade versus low-grade serous carcinoma of the ovary are 2 distinct patient populations. Adoption of the 2-tier grading system provides a simple yet precise framework for predicting clinical outcomes.

Platelet-derived growth factor receptor (PDGFR)a expression was found in ovarian cancer cells and tumors by microarray hybridization. This led us to test whether ovarian cancers also produce ligands for this receptor, as this would demonstrate that such malignancies support their own growth and spread through autocrine activation. We assayed the expression of ligands for the PDGFR in ovarian tumors, cell lines and peritoneal fluid using RT-PCR, immunohistochemistry (IHC) and ELISA. We detected strong mRNA expression for the PDGFRa ligands in most ovarian tumors. Receptor and ligand expressions (PDGFRa and PDGF AB) were also detected by IHC in, respectively, 34 and 32 of 47 ovarian tumors. The stainings for PDGFRa and PDGF AB were strongly correlated (P-value ¼ 0.014), suggesting that an autocrine loop is functional in ovarian cancer. PDGF AA and BB were quantified in peritoneal fluid by ELISA. Both ligands are secreted at higher levels in ovarian cancer ascites specimens (n ¼ 54) than in fluid from nonmalignant disorders (n ¼ 8). PDGF was detected in media conditioned by ovarian cancer cells. Such conditioned media induced activation of the PDGFR, Akt and MAPK and stimulated cell proliferation. A neutralizing PDGF antibody blocked these effects. Specific PDGFR inhibition by siRNA or a neutralizing antibody to the receptor inhibited PDGF-stimulated receptor activation and cell proliferation, suggesting that receptor targeting has a role in ovarian cancer treatment.

Purpose Aggressive pancreatic cancer is commonly associated with a dense desmoplastic stroma, which forms a protective niche for cancer cells. The objective of the study was to determine the functions of tissue transglutaminase (TG2), a Ca2+-dependent enzyme which crosslinks proteins through transamidation and is abundantly expressed by pancreatic cancer cells in the pancreatic stroma. Experimental Design Orthotopic pancreatic xenografts and co-culture systems tested the mechanisms by which the enzyme modulates tumor-stroma interactions. Results We show that TG2 secreted by cancer cells effectively molds the stroma by crosslinking collagen, which in turn activates fibroblasts and stimulates their proliferation. The stiff fibrotic stromal reaction conveys mechanical cues to cancer cells leading to activation of the YAP/TAZ transcription factors, promoting cell proliferation and tumor growth. Stable knockdown of TG2 in pancreatic cancer cells led to decreased size of pancreatic xenografts. Conclusions Taken together, our results demonstrate that TG2 secreted in the tumor microenvironment orchestrates the crosstalk between cancer cells and stroma fundamentally impacting tumor growth. Our study supports TG2 inhibition in the pancreatic stroma as a novel strategy to block pancreatic cancer progression.

Metastatic colonization involves paracrine/juxtacrine interactions with the microenvironment inducing an adaptive response through transcriptional regulation. However, the identities of transcription factors (TFs) induced by the metastatic microenvironment in ovarian cancer (OC) and their mechanism of action is poorly understood. Using an organotypic 3D culture model recapitulating the early events of metastasis, we identified ETS1 as the most upregulated member of the ETS family of TFs in metastasizing OC cells as they interacted with the microenvironment. ETS1 was regulated by p44/42 MAP kinase signaling activated in the OC cells interacting with mesothelial cells at the metastatic site. Human OC tumors had increased expression of ETS1, which predicted poor prognosis. ETS1 regulated OC metastasis both in vitro and in mouse xenografts. A combination of ChIP-seq and RNA-seq analysis and functional rescue experiments revealed FAK as the key transcriptional target and downstream effector of ETS1. Taken together, our results indicate that ETS1 is an essential transcription factor induced in OC cells by the microenvironment, which promotes metastatic colonization though the transcriptional upregulation of its target FAK.

Tissue transglutaminase (TG2) is a multifunctional protein that binds to fibronectin and exerts protein transamidating activity in the presence of Ca(2+). We previously reported that TG2 is upregulated in ovarian tumors and enhances intraperitoneal (i.p.) metastasis. TG2 is secreted abundantly in ovarian cancer (OC) ascites as an active enzyme, yet its function in the extracellular compartment remains unknown. To study the distinct functions of secreted TG2, we used recombinant His6-tagged TG2 and catalytically inactive enzyme in vitro and in vivo. By using i.p. and orthotopic ovarian xenografts, we show that extracellular transglutaminase promoted OC peritoneal metastasis. The main pathway activated by extracellular TG2 was noncanonical nuclear factor-kappa B (NF-κB) signaling, and the enzymatic function of the protein was required to induce phosphorylation of IκB kinase α and processing of the precursor protein p100 into the active p52 subunit. A specific target of TG2-activated p52/RelB complex is the hyaluronan receptor, CD44. Noncanonical NF-κB activation by extracellular TG2 induced CD44 up-regulation and epithelial-to-mesenchymal transition, contributing to increased cancer cell invasiveness and OC peritoneal dissemination. Taken together, our data support that noncanonical NF-κB activation is the pathway through which extracellular TG2 promotes OC metastasis.