Establishment of canine hemangiosarcoma xenograft models expressing endothelial growth factors, their receptors, and angiogenesis-associated homeobox genes

Abstract

BackgroundHuman hemangiosarcoma (HSA) tends to have a poor prognosis; its tumorigenesis has not been elucidated, as there is a dearth of HSA clinical specimens and no experimental model for HSA. However, the incidence of spontaneous HSA is relatively high in canines; therefore, canine HSA has been useful in the study of human HSA. Recently, the production of angiogenic growth factors and their receptors in human and canine HSA has been reported. Moreover, the growth-factor environment of HSA is very similar to that of pathophysiological angiogenesis, which some homeobox genes regulate in the transcription of angiogenic molecules. In the present study, we established 6 xenograft canine HSA tumors and detected the expression of growth factors, their receptors, and angiogenic homeobox genes.MethodsSix primary canine HSAs were xenografted to nude mice subcutaneously and serially transplanted. Subsequently, the expressions of vascular endothelial growth factor (VEGF)-A, basic fibroblast growth factors (bFGF), flt-1 and flk-1 (receptors of VEGF-A), FGFR-1, and angiogenic homeobox genes HoxA9, HoxB3, HoxB7, HoxD3, Pbx1, and Meis1 were investigated in original and xenograft tumors by histopathology, immunostaining, and reverse transcription polymerase chain reaction (RT-PCR), using canine-specific primer sets.ResultsHistopathologically, xenograft tumors comprised a proliferation of neoplastic cells that were varied in shape, from spindle-shaped and polygonal to ovoid; some vascular-like structures and vascular clefts of channels were observed, similar to those in the original tumors. The expression of endothelial markers (CD31 and vWF) was detected in xenograft tumors by immunohistochemistry and RT-PCR. Moreover, the expression of VEGF-A, bFGF, flt-1, flk-1, FGFR-1, HoxA9, HoxB3, HoxB7, HoxD3, Pbx1, and Meis1 was detected in xenograft tumors. Interestingly, expressions of bFGF tended to be higher in 3 of the xenograft HSA tumors than in the other tumors.ConclusionWe established 6 xenograft canine HSA tumors in nude mice and found that the expressions of angiogenic growth factors and their receptors in xenograft HSAs were similar to those in spontaneous HSA. Furthermore, we detected the expression of angiogenic homeobox genes; therefore, xenograft models may be useful in analyzing malignant growth in HSA.

Pharmacologic Inhibition of MEK Signaling Prevents Growth of Canine Hemangiosarcoma

“…This is reminiscent of Kaposi sarcoma, another endothelial malignancy, in which proliferating spindle cells release cytokines that drive tumor growth in a paracrine fashion. Consistent with this, elevated levels of VEGF and bFGF, as well as Flt4 (VEGFR3) and FGFR-1, have been detected in association with canine AS (32, 33) and human angiosarcoma (7, 8, 34). …”

Overexpression of Peroxiredoxin 6 Protects Neoplastic Cells against Apoptosis in Canine Haemangiosarcoma

“…Consequently, canine HSA is a useful comparative model for studying the biology of human AS (Fosmire et al, 2004). Although the molecular mechanisms of HAS tumorigenesis remain largely unknown, there is growing evidence that the dysregulation of molecular pathways controlling angiogenesis might be important in the pathogenesis of malignancies of endothelial cell origin, as has been observed for other cancers (Yonemaru et al, 2006;Kodama et al, 2009;Murakami et al, 2009;Asa et al, 2012;Anwar et al, 2015).…”

Modeling human endothelial cell transformation in vascular neoplasias

“…Similar to the polyoma middle T-antigen-driven xenograft tumors, patient-derived hemangioma progenitor cells were shown to form transient subcutaneous tumors when engrafted in immunocompromised mice (Khan et al, 2008; Xu et al, 2011). Xenograft tumors have also been established from canine angiosarcoma (Akhtar et al, 2004; Kodama et al, 2009). In addition to providing a useful model for preclinical testing of novel therapeutics, xenografts potentially provide a means for expansion of rare tumor material via serial transplantation (Khan et al, 2008).…”