Procoagulant activity on tumor cells can enhance their ability to spread via the circulation to colonize distant organs. Toward defining the relative importance of the main host responses to coagulation for hematogenous metastasis, we examined lung metastases after intravenous injection of melanoma cells in Nf-E2 ؊/؊ mice, which have virtually no circulating platelets; Par4 ؊/؊ mice, which have platelets that fail to respond to thrombin; Par1 and Par2 ؊/؊ mice, which have markedly attenuated endothelial responses to coagulation proteases; and Fib ؊/؊ mice, which lack fibrinogen. In a severe combined immunodeficiency (SCID) background, median lung tumor count in Nf-E2 ؊/؊ , Par4 ؊/؊ , and Fib ؊/؊ mice was 6%, 14%, and 24% of wild type, respectively; total tumor burden was only 4%, 9%, and 3% of wild type, respectively. Similar results were seen in a syngeneic C57BL6 background. By contrast, deficiencies of protease-activated receptor 1 (PAR1) or PAR2 did not provide protection. These results provide strong genetic evidence that platelets play a key role in hematogenous metastasis and contribute to this process by both thrombin-dependent and -independent mechanisms. Importantly, PAR4 heterozygosity conferred some protection against metastasis in this model. IntroductionSeveral critical steps must be fulfilled to enable tumor cells to metastasize. The success of one such step, tissue colonization by tumor cells moving through the vascular compartment (hematogenous metastasis), is more likely if the tumor cell can activate the coagulation cascade. Such tumor cell procoagulant activity has been correlated with malignant progression of several types of human cancer. [1][2][3][4][5][6] In mouse models, introduction of tissue factor, the main trigger for coagulation, into nonmetastatic cell lines can confer efficient hematogenous metastasis, 7,8 and inhibitors of coagulation can inhibit hematogenous metastasis. [8][9][10][11][12] It seems likely that procoagulant activity promotes hematogenous metastasis at least in part by helping tumor cells to lodge in the microvasculature 9,10 so as to allow diapedesis into tissue 13 or intravascular growth of secondary tumors. 14 This might be accomplished by a number of host responses to coagulation proteases (Figure 1). Platelets can act as bridges between endothelial cells and lymphocytes 15 or monocytes, 16 and thrombin activation of platelets can enhance this function. 16 Thus, coagulation proteases might activate platelets such that they bind tumor cells to the vessel wall. Platelet activation and fibrin formation in response to coagulation proteases formed on the tumor cell surface might also promote its incorporation into microthrombi that lodge in the microvasculature. 13 Alternatively, endothelial cells respond to coagulation proteases by displaying a variety of adhesion molecules, 17 and this activity might tether tumor cells or tumor cell-platelet complexes to the vessel wall (Figure 1). We used knock-out mice to examine the relative importance of platelets, platelet a...

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide. New animal models that faithfully recapitulate human HCC phenotypes are required to address unmet clinical needs and advance standard-of-care therapeutics. This study utilized the Oncopig Cancer Model to develop a translational porcine HCC model which can serve as a bridge between murine studies and human clinical practice. Reliable development of Oncopig HCC cell lines was demonstrated through hepatocyte isolation and Cre recombinase exposure across 15 Oncopigs. Oncopig and human HCC cell lines displayed similar cell cycle lengths, alpha-fetoprotein production, arginase-1 staining, chemosusceptibility, and drug metabolizing enzyme expression. The ability of Oncopig HCC cells to consistently produce tumors in vivo was confirmed via subcutaneous (SQ) injection into immunodeficient mice and Oncopigs. Reproducible development of intrahepatic tumors in an alcohol-induced fibrotic microenvironment was achieved via engraftment of SQ tumors into fibrotic Oncopig livers. Whole-genome sequencing demontrated intrahepatic tumor tissue resembled human HCC at the genomic level. Finally, Oncopig HCC cells are amenable to gene editing for development of personalized HCC tumors. This study provides a novel, clinically-relevant porcine HCC model which holds great promise for improving HCC outcomes through testing of novel therapeutic approaches to accelerate and enhance clinical trials.

Bladder cancer (BC) is the 10th most common neoplasia worldwide and holds expensive treatment costs due to its high recurrence rates, resistance to therapy and the need for lifelong surveillance. Thus, it is necessary to improve the current therapy options and identify more effective treatments for BC. Biological models capable of recapitulating the characteristics of human BC pathology are essential in evaluating the effectiveness of new therapies. Currently, the most commonly used BC models are experimentally induced murine models and spontaneous canine models, which are either insufficient due to their small size and inability to translate results to clinical basis (murine models) or rarely spontaneously observed BC (canine models). Pigs represent a potentially useful animal for the development of personalized tumors due to their size, anatomy, physiology, metabolism, immunity, and genetics similar to humans and the ability to experimentally induce tumors. Pigs have emerged as suitable biomedical models for several human diseases. In this sense, the present perspective focuses on the genetic basis for BC; presents current BC animal models available along with their limitations; and proposes the pig as an adequate animal to develop humanized large animal models of BC. Genetic alterations commonly found in human BC can be explored to create genetically defined porcine models, including the BC driver mutations observed in the FGFR3, PIK3CA, PTEN, RB1, HRAS, and TP53 genes. The development of such robust models for BC has great value in the study of pathology and the screening of new therapeutic and diagnostic approaches to the disease.

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