Osteosarcoma is the most common primary malignant tumour of bones in dogs, occurring most frequently in the axial skeleton (75%), it is locally aggressive with a high angiogenetic and metastatic potential. VEGFRs (VEGFR1, VEGFR2 and VEGFR3) are the most important receptors regulating tumoral angiogenesis following the interaction with VEGF factor. The aim of this study was to investigate VEGFR-1, VEGFR-2 and VEGFR-3 and VEGFA expression in canine OSA tissues and cell lines to evaluate its prognostic value in relation to clinical outcome of the canine patients. Thirty-one dogs diagnosed with canine appendicular were enrolled in the study. All the animals underwent a complete clinical staging and were treated with surgery and then they were followed until the recurrence of the neoplasm or death. All the samples were histologically evaluated and immunohistochemically tested for VEGFA, VEGFR-1, VEGFR-2 and VEGFR-3. Histological and immunohistochemical results were evaluated in relation to clinic-pathological data. Total RNA was extracted from 8 canine osteosarcoma cell lines and expression of VEGFR1, VEGFR2 and VEGFR3 canine gene were evaluated by qPCR. VEGF was present in all analyzed cases and particularly was widely expressed in 33% of cases, moderately expressed in 46% of cases and poorly expressed in 20% of OSA analyzed. Regarding the expression of the receptors we found that the 64.52% of canine OSA were positive for VEGFR-1, 70.97% were positive for VEGFR-2, while 74.19% cases per positive for VEGFR-3. The positivity for VEGFR-1 was statistically associated with the positivity for VEGF (P<0.05) and VEGFR-3 (P<0.05). Statistical analyses comparing the immunohistochemical results with all clinical-pathological data revealed no statistical associations. Molecular data showed that only D22 cell lines over-expressed all three VEGFRs while VEGFR2 was expressed only by Wall and D22 cell lines and VEGFR3 by D22, Pedro, Lord and Wall cell lines if compared to osteoblastic cell line. This is the first study investigating VEGFRs and VEGFA expression in canine OSA and cell lines demonstrating that those receptors are widely expressed in this tumor. No statistical association has been found between VEGFRs expression and clinical and histopathological features while a significant association between VEGFR1 and VEGFA has been found. In human osteosarcoma the autocrine loop VEGFR-1/VEGFA is correlated to the malignant progression while VEGFR2 and VEGFR3 seem not to be involved. These preliminary data suggest that also in canine OSA this autocrine loop can be relevant in the progression of canine osteosarcoma as demonstrated in canine mammary tumors and that be considered a suitable target for innovative targeted therapies.

VEGFA AND VEGFRS EXPRESSION IN CANINE APPENDICULAR OSTEOSARCOMA

MILLANTA, FRANCESCA;POLI, ALESSANDRO;
2016

Abstract

Osteosarcoma is the most common primary malignant tumour of bones in dogs, occurring most frequently in the axial skeleton (75%), it is locally aggressive with a high angiogenetic and metastatic potential. VEGFRs (VEGFR1, VEGFR2 and VEGFR3) are the most important receptors regulating tumoral angiogenesis following the interaction with VEGF factor. The aim of this study was to investigate VEGFR-1, VEGFR-2 and VEGFR-3 and VEGFA expression in canine OSA tissues and cell lines to evaluate its prognostic value in relation to clinical outcome of the canine patients. Thirty-one dogs diagnosed with canine appendicular were enrolled in the study. All the animals underwent a complete clinical staging and were treated with surgery and then they were followed until the recurrence of the neoplasm or death. All the samples were histologically evaluated and immunohistochemically tested for VEGFA, VEGFR-1, VEGFR-2 and VEGFR-3. Histological and immunohistochemical results were evaluated in relation to clinic-pathological data. Total RNA was extracted from 8 canine osteosarcoma cell lines and expression of VEGFR1, VEGFR2 and VEGFR3 canine gene were evaluated by qPCR. VEGF was present in all analyzed cases and particularly was widely expressed in 33% of cases, moderately expressed in 46% of cases and poorly expressed in 20% of OSA analyzed. Regarding the expression of the receptors we found that the 64.52% of canine OSA were positive for VEGFR-1, 70.97% were positive for VEGFR-2, while 74.19% cases per positive for VEGFR-3. The positivity for VEGFR-1 was statistically associated with the positivity for VEGF (P<0.05) and VEGFR-3 (P<0.05). Statistical analyses comparing the immunohistochemical results with all clinical-pathological data revealed no statistical associations. Molecular data showed that only D22 cell lines over-expressed all three VEGFRs while VEGFR2 was expressed only by Wall and D22 cell lines and VEGFR3 by D22, Pedro, Lord and Wall cell lines if compared to osteoblastic cell line. This is the first study investigating VEGFRs and VEGFA expression in canine OSA and cell lines demonstrating that those receptors are widely expressed in this tumor. No statistical association has been found between VEGFRs expression and clinical and histopathological features while a significant association between VEGFR1 and VEGFA has been found. In human osteosarcoma the autocrine loop VEGFR-1/VEGFA is correlated to the malignant progression while VEGFR2 and VEGFR3 seem not to be involved. These preliminary data suggest that also in canine OSA this autocrine loop can be relevant in the progression of canine osteosarcoma as demonstrated in canine mammary tumors and that be considered a suitable target for innovative targeted therapies.
978-88-909092-8-3
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/812848
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