Canine malignant hemangiosarcoma as a model of primitive angiogenic endothelium

Abstract

Hemangiosarcoma (HSA) is a common untreatable cancer of dogs that resembles human angiosarcoma. Detailed studies of these diseases have been historically hindered by the paucity of suitable reagents. Here, we show that expression of CD117 (c-Kit) can distinguish primitive (malignant) from mature (benign) proliferative endothelial lesions, and we describe eight independent cell lines derived from canine HSA explants. Endothelial origin was confirmed by sustained expression of surface CD105 (endoglin), CD146 (MUC18), and CD51/CD61 (a v b 3 integrin). The cell lines showed anchorage-independent growth and were motile and invasive when cultured on a basement membrane matrix. They required endothelial growth factors for growth and survival, and they could be induced to form tubular structures resembling blood vessels when cultured under low calcium conditions. The formation of vessel-like structures was blocked by nicotine, and restored by FK506, suggesting that 'nuclear factor of activated T cells' activity prevents differentiation of these cells. In summary, these cell lines represent a unique and novel resource to improve our understanding of endothelial cell biology in general and canine HSA in particular.

Nicotine Activates Nuclear Factor of Activated T Cells c2 (NFATc2) and Prevents Cell Cycle Entry in T Cells

“…The antiproliferative effects of nicotine were not simply due to abrogation of antigen receptor signals since nicotine did not affect the increased expression of CDK6 (or IL-2 receptors). Moreover, our experiments using endothelial cells indicate that activation of NFAT transcription factors is not restricted to T cells (Fosmire et al, 2004).…”

“…Thus, paradoxical effects of nicotine on proliferation in different non-neuronal cell types might be due to the contextual cross talk between distinct nAChR and growth factor receptors (Leonard and Bertrand, 2001) or to the activation of different NFAT proteins (Kiani et al, 2000;Crabtree and Olson, 2002). In fact, such distinct nicotine effects may even occur in the same cell type at different stages of differentiation (Fosmire et al, 2004).…”

“…The effects of nicotine in DD-1 cells were not restricted to the transfected GFP-NFATc2. Nicotine treatment of untransfected cells led to decreased vascular endothelial growth factor expression and prevented aggregation of the cells into vessel-like structures, and both of these events were sensitive to FK506 (Fosmire et al, 2004), suggesting they were mediated by activation of endogenous NFAT proteins.…”

Explant culture of sarcoma patients' tissue

“…Higher success rates were also related to malignancy in other tumors listed in Table 4. 18,[30][31][32][33] A similar trend was observed in osteogenic tumors and tumors of uncertain differentiation. In comparison, cells derived from metastatic colon cancer could not be established by the explant technique and instead required patient-derived xenograft (PDX) transplantation, indicating an inverse relationship between success and malignancy.…”

“…[13][14][15][16][17][18][19] As we assumed it to be difficult to optimize enzymatic digestion protocols for each single tissue type affected by sarcoma and because pleural effusion is mainly performed in patients with end-stage lung metastases only, we explored here the potential to obtain patient-derived cell lines from sarcoma patients using the explant technique. Notably, apart from incidental case reports, [20][21][22][23][24][25] this technique has so far not been investigated thoroughly for sarcomas in general or for specific sarcoma entities.…”