Investigation of the beta 2 adrenergic receptor (B2-AR) pathway in canine hemangiosarcoma

hemangiosarcoma;beta adrenergic;cancer;stress;canine;src

Portela, Roberta ; Wypij ; Jackie M.

关键词: hemangiosarcoma;    beta adrenergic;    cancer;    stress;    canine;    src;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/72904/Roberta_Portela.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Canine hemangiosarcoma is a highly metastatic cancer arising from vascular endothelial cells. Itis one of the most aggressive canine cancers and most dogs die from this disease within a fewmonths of the diagnosis. Despite advancements in veterinary oncology, there has been minimalimprovement in the overall survival time even with standard treatment, which includes surgeryand chemotherapy. Propranolol, an oral drug originally developed for the treatment ofcardiovascular diseases, has been successfully used for the treatment of infantile hemangiomawhich is a benign neoplasia of vascular endothelial cells. Propranolol blocks adrenergicreceptors, which would otherwise bind to catecholamines responsible for the “stress signal”leading to many physiologic changes. Stress has been implicated in many models ofcarcinogenesis and tumor progression. Given the relationship between stress and cancer, as wellas similarities between canine hemangiosarcoma and infantile hemangioma, we sought toinvestigate the presence of the beta 2 adrenergic receptor and the effects of propranolol in caninehemangiosarcoma. We demonstrated the presence of the beta 2 adrenergic receptor viaimmunohistochemistry in all 18 tissue samples of spontaneous canine splenic hemangiosarcoma and in canine hemangiosarcoma cell lines Fitz and DEN, cell line receptor expression was alsoconfirmed with Western blot. Src, a possible intermediary downstream protein involved inadrenergic signaling was also investigated and both Fitz and DEN exhibited the presence of theSrc protein in Western blot. Activation of this pathway would involve phosphorylation of Srcupon catecholamine binding to the receptor, which was investigated through Western blot. Fitzand DEN exhibited basal phosphorylation of Src and after treatment with norepinephrine, andFitz exhibited greater phosphorylation (23% increase compared to basal control) after 60-minuteexposure to the agonist. Fitz cells were pretreated with a biologically achievable dose of propranolol followed by the agonist, and a modest decrease in phosphorylation was observed(11% decrease compared to basal level). Further investigation into the biological effects ofpropranolol in Fitz and DEN revealed a decrease in VEGF secretion, increase in proliferationand decrease in cell migration. Reduction in VEGF secretion was evaluated via ELISA and itwas present at propranolol doses greater than 10 μM for DEN and Fitz, achieving a maximumreduction of 21% in DEN and 44% in Fitz compared to untreated cells. Cell proliferation wasmeasured through MTS assay, which revealed an increase in cell proliferation only in Fitz cellstreated with 0.1 μM of NE (25% increase) and cells treated with 0.1 μM of propranolol (30%increase). Cell migration was evaluated with a scratch assay and was decreased only when cellswere treated with propranolol at a high dose (100 μM). Taken together, the findings of this studyshow that beta 2 adrenergic receptors are expressed by canine hemangiosarcoma, Src may beinvolved in the downstream signaling from the receptor and blockade of the receptor leads tomild to moderate effects in cell angiogenesis, proliferation and migration.