Effects of epidermal growth factor receptor kinase inhibition on radiation response in canine osteosarcoma cells

Abstract

BackgroundRadiation therapy is a palliative treatment modality for canine osteosarcoma, with transient improvement in analgesia observed in many cases. However there is room for improvement in outcome for these patients. It is possible that the addition of sensitizing agents may increase tumor response to radiation therapy and prolong quality of life. Epidermal growth factor receptor (EGFR) expression has been documented in canine osteosarcoma and higher EGFR levels have been correlated to a worse prognosis. However, effects of EGFR inhibition on radiation responsiveness in canine osteosarcoma have not been previously characterized. This study examined the effects of the small molecule EGFR inhibitor erlotinib on canine osteosarcoma radiation responses, target and downstream protein expression in vitro. Additionally, to assess the potential impact of treatment on tumor angiogenesis, vascular endothelial growth factor (VEGF) levels in conditioned media were measured.ResultsErlotinib as a single agent reduced clonogenic survival in two canine osteosarcoma cell lines and enhanced the impact of radiation in one out of three cell lines investigated. In cell viability assays, erlotinib enhanced radiation effects and demonstrated single agent effects. Erlotinib did not alter total levels of EGFR, nor inhibit downstream protein kinase B (PKB/Akt) activation. On the contrary, erlotinib treatment increased phosphorylated Akt in these osteosarcoma cell lines. VEGF levels in conditioned media increased after erlotinib treatment as a single agent and in combination with radiation in two out of three cell lines investigated. However, VEGF levels decreased with erlotinib treatment in the third cell line.ConclusionsErlotinib treatment promoted modest enhancement of radiation effects in canine osteosarcoma cells, and possessed activity as a single agent in some cell lines, indicating a potential role for EGFR inhibition in the treatment of a subset of osteosarcoma patients. The relative radioresistance of osteosarcoma cells does not appear to be related to EGFR signalling exclusively. Angiogenic responses to radiation and kinase inhibitors are similarly likely to be multifactorial and require further investigation.

Effects of the potassium‐sparing diuretic amiloride on chemotherapy response in canine osteosarcoma cells

“…Both D17 and Abrams cell lines were characterized and published as canine OSA cells based on morphology and xenograft analysis . Dharma was isolated from a primary tumor by Dr Anthony J. Mutsaers and verified to be OSA by histopathology of tumors produced from xenograft implantation in nude mice . All cells were cultured in high glucose Dulbecco's Modified Eagle Medium (DMEM) with 10% fetal bovine serum (FBS) and 100 U/mL penicillin/streptomycin (Thermo Fisher Scientific, Waltham, Massachusetts) and maintained in a humidified incubator at 37°C with 5% CO 2 .…”

In vitro and in vivo effects of toceranib phosphate on canine osteosarcoma cell lines and xenograft orthotopic models

“…Canine osteosarcoma (OSA) represents the most common primary malignant bone tumour in dogs, accounting for more than 80% of all bone tumours; it is locally aggressive and is characterized by a high metastatic potential and poor prognosis . Furthermore, the role of several tyrosine kinase receptors (TKRs) in the pathogenesis of canine OSA was recently demonstrated, which reveals the utility of tyrosine kinase inhibitors (TKIs) against specific targets …”

“…1,3,4 Furthermore, the role of several tyrosine kinase receptors (TKRs) in the pathogenesis of canine OSA was recently demonstrated, [5][6][7] which reveals the utility of tyrosine kinase inhibitors (TKIs) against specific targets. 8,9 TKIs have radically changed the treatment approach and prognosis of several human tumours 10,11 ; further, in veterinary medicine, this class of molecules has been shown to be promising in the treatment of a few cancer histotypes. [12][13][14][15] Toceranib phosphate (TOC; Palladia, Zoetis) is a specific veterinary TKI that selectively inhibits VEGFR-2, PDGFRs and c-Kit and is currently approved for the treatment of mast cell tumours.…”

Osteosarcoma in Dogs: Diagnosis and Treatment - A Literature Review

“…These are: Chen at. Al [2][3][4][5][7][8][9][10][11][12][13][14]. The animals described in this review, the animals were middle aged to elderly and medium to large size, except for one case of a Maltese dog reported by Teixeira et al [18].…”

“…Mantovani et al [5], with the aim of improving the results of this therapy, since osteosarcoma cells are historically resistant to ionizing radiation, combined Erlotinib, a selective epidermal growth factor (EGFR) inhibitor, with radiation therapy in its study in vitro, noting that Erlotinib promoted a modest increase in the therapeutic effects of radiation therapy. Another in vitro study by Cannon et al [26] makes use of aurora kinase inhibitors, which is essential for cell proliferation.…”