Inhibitory Effects of Glucocorticoids on Proliferation of Canine Mast Cell Tumor.

Abstract

ABSTRACT. The inhibitory effect of glucocorticoids (GCs) on proliferation of canine mast cell tumor (MCT) was studied using two types of MCT cells; JuMC cells and LuMC cells derived from spontaneous canine cutaneous and intestinal MCT, respectively. In in vitro study, growth of JuMC cells was significantly inhibited with more than 1 nM GCs and apoptotic-like cell death was seen, while that of LuMC cells was never inhibited even with 10 µM GCs. Growth rate of masses in nude mice developed by inoculation of JuMC cells was reduced in a dose-dependent manner by administration of GC, while growth inhibition of masses developed by inoculation of LuMC cells was minimal with increasing GC doses. We have established both cutaneous and intestinal types of canine MCT cells from the spontaneous canine cases [18,19]. In this experiment, in vitro and in vivo inhibitory effects of GCs on these tumor cells were investigated and cytoplasmic GC receptors of these cells were measured. MATERIALS AND METHODS MCT cells and culture method:JuMC cell was derived from spontaneous canine cutaneous MCT clinically categorized as intermediately-differentiated MCT, which had been treated with prednisolone (PRD) as one of the chemotherapeutic agents. This cell was maintained in our laboratory by in vivo passage (subcutaneous inoculation) in female nude mice (5 week old, BALB/c-nu/nu Slc, Nippon SLC Inc., Shizuoka, Japan) in every 6 to 10 weeks. This cell was characterized as rat connective tissue type mast cell by morphology and the manner of degranuration by various stimulations [19]. Doubling time of this cell in vitro was over 300 hr. In this study JuMC cells with 20 to 24 passages were used.JuMC cells were obtained by excision of the mass from the nude mouse. The mass was minced in phosphate buffered saline (PBS( )), filtrated through a 53-µm mesh, washed and centrifuged at 1,000 rpm for 5 min. Then it was resuspended and cultured in RPMI-1640 medium (2 mM L-glutamine, 10 U/ml penicillin, 10 µg/ml streptomycin, 50 µM 2-mercaptoethanol) with 10% heat-inactivated fetal bovine serum (FBS) (JRH Biosciences, U.S.A.) at 37°C in humidified air with 5% CO 2 .LuMC cells were derived from spontaneous canine intestinal MCT. The case also had a history of receiving PRD treatment for indistinct eosinophilia. This cell was Mast cell tumor (MCT) accounts for 7 to 21% of all skin tumors and 11 to 27% of all malignant skin tumors in dogs [9,23]. Canine MCT occurs primarily in the dermis and subcutaneous tissues, which is called as cutaneous MCT. Mast cell tumor cells have cytoplasmic granules containing several vasoactive substances like histamine and heparin, which often cause various clinical symptoms such as gastric ulcer and bleeding tendency in the tumor patients. Surgical excision is the choice of treatment for cutaneous MCT, however it often metastasizes to the adjacent and/or distant skin and visceral lymph nodes. In addition, the vasoactive substances of this tumor affect the systemic conditions. Another MCT, called as intestinal MCT, is derived f...

Retinoid Receptors and the Induction of Apoptosis in Canine Osteosarcoma Cells.

“…The presence of RARs and RXRs may not always predict the responsiveness of the cell to retinoid treatment. It has recently been shown that the resistance to response is partially attributable to mutations in glucocorticoid receptors [19]. A similar phenomenon might have occurred in the retinoid receptors of the osteosarcoma cells tested in this study.…”

Expression of the MDR1 Gene and P-Glycoprotein in Canine Mast Cell Tumor Cell Lines

“…Frequency and intensity of the chemotherapy may potentially give influences on MDR1 expression, however, none of these factors correlated with MDR1 status of the cell lines investigated in this study [10,23]. Alternatively, TiMC cells may not show induction of MDR1 gene expression in response to some factors, similar to the previously reported MDR1-deficient genotype [13,20].…”

“…Cell lines: TiMC, CoMS and LuMC canine MCT cell lines were originated from a cutaneous MCT, an oralmucosal MCT and a gastrointestinal MCT, respectively [10,23]. CoMS cell line was kindly provided by Laboratory of Veterinary Surgery, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University.…”

Chlorambucil and prednisolone chemotherapy for dogs with inoperable mast cell tumours: 21 cases

“…The purpose of this study was to assess the response to a previously unpublished chemotherapy protocol for gross MCT in dogs for whom surgery and/or radiotherapy were not suitable using two agents that have shown efficacy against round cell tumours. Prednisolone is widely used in chemotherapy regimens for canine MCTs (McCaw and others 1994, Thamm and others 1999, 2006, Davies and others 2004) and has been shown to inhibit mast cell proliferation in vitro (Takahashi and others 1997); it has also been shown to cause a reduction of size of gross MCTs before radiotherapy (Dobson and others 2004) or surgery (Stanclift and Gilson 2008). Chlorambucil is an alkylating agent that has therapeutic indications in canine round cell tumours, including MCT, lymphoma, chronic lymphoid leukaemia and some myelomas (Carberry and others 1987, Chun and others 2007).…”