Cytotoxicity on low-grade canine meningioma with the use of somatostatin analog (octreotide): An in vitro study

Background Meningioma is the most common tumor of the central nervous system of dogs. For this tumor, surgery remains the treatment of choice, either alone or in combination with radiotherapy. Unfortunately, chemotherapeutic strategies are practically absent in dogs and palliative therapies are the only option to surgery. Somatostatin receptor subtype 2 (SSTR2) is expressed in canine meningioma. Since the potent cell-proliferation inhibiting effect of somatostatin (SST), the aim of this study was to investigate in vitro the effects of octreotide, as SST analog, in the viability of canine meningioma.Methods Four surgical canine meningiomas were used in this study to establish cell cultures. Expression of SSTR2 was verified with immunolabelling in FFPE samples and cell cultures. The effects of octreotide on cell viability were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT). After 24 hours they were exposed to different concentrations of octreotide (0.1 nM, 1 nM, 10 nM, 100 nM) for 24 and 48 hours.Results All meningiomas consisted of grade I tumors. The cultured neoplastic cells expressed SSTR2 from 80% to 100%. Octreotide significantly increased cell death after 48 hours of continuous exposure, with 10 and 100 nM octreotide doses. The percentage of cell viability was 80.92 +/- 4.9 and 80.49 +/- 3.61, compared to the control, respectively, consistent with decreased cell viability of about 20% for both doses.Conclusions Octreotide reduced the alive neoplastic cultured cells of low-grade canine meningioma in a dose-dependent pattern with continuous exposition for 48 hours. These results support an alternative systemic treatment of meningioma with octreotide in the dog.Meningiomas are common tumors that grow from the protective covering around the brain and spinal cord. Currently, there are no effective drugs to treat meningiomas. In this study, researchers wanted to test whether a drug called octreotide could help treat meningiomas. They took meningiomas from 4 dogs and grew the tumor cells in the lab. Then, they treated the dog meningioma cells with different doses of octreotide for 24 and 48 hours. Their results showed that octreotide reduced the number of tumor cells by about 20% at the highest doses after 48 hours of treatment.