Glucocorticoid sensitivity depends on expression levels of glucocorticoid receptors in canine neoplastic mast cells

Comparison of chemotherapy outcomes between normal and high serum cortisol concentration in dogs with lymphoma

BACKGROUND

Increased serum cortisol (COR) concentrations may induce glucocorticoid resistance by down-regulation of glucocorticoid receptor (GCR), resulting in decreased chemotherapy efficacy in dogs with lymphoma.

HYPOTHESIS

Investigate the relationship between serum COR concentrations and chemotherapy outcomes in dogs with lymphoma.

ANIMALS

Thirty client-owned dogs with lymphoma, with serum COR concentration measured using serum samples collected at diagnosis.

METHODS

Retrospective study. Dogs were divided into 2 groups based on serum COR concentrations: a normal group (n = 16) with COR concentrations <6 μg/dL and a high group (14) with COR concentrations ≥6 μg/dL. We compared signalment, clinical signs, stage, type of lymphoma, adrenal gland size, alkaline phosphatase (ALP) activity, response to chemotherapy, progression-free survival (PFS), overall survival (OS), and rate of P-glycoprotein (P-gp)- and GCR-positive cells between the 2 groups.

RESULTS

No significant differences were found in the demographic characteristics between the 2 groups. However, the high COR group exhibited a significantly lower response to chemotherapy, PFS, and OS compared with the normal COR group. Serum ALP activity was significantly higher in the high COR group than in the normal COR group. Adrenal gland size was also significantly larger in the high COR group. Although no significant differences were found in the rate of P-gp-positive cells between the 2 groups, the rate of GCR-positive cells was significantly lower in the high COR group.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our data suggests that measurement of serum COR concentrations may serve as a potential prognostic factor and evaluation index.

Tyrosine kinase inhibitors as an alternative treatment in canine mast cell tumor

The current gold standard treatment for canine mast cell tumors (MCT) uses vinblastine sulfate (VBL) as chemotherapy, although tyrosine kinase inhibitors (TKI) have recently been shown to be worthy candidates for treatment. This systematic review aimed to analyze the overall survival (OS), progression-free survival (PFS), overall response rate (ORR), and complete (CR) or partial response (PR) in dogs with MCT treated with TKI compared to standard VBL treatment. The systematic review was registered in the Open Science Framework (OSF) database under the identifier 10.17605/OSF.IO/WYPN4 (https://osf.io/). An electronic search was performed in nine databases. References from eligible studies were also selected to find more registers. A total of 28 studies met the eligibility criteria, and one more was recovered from the references of eligible studies, totaling 29 selected studies. The overall response rate, complete response, and partial response were higher in dogs treated with tyrosine kinase inhibitors than in dogs treated with vinblastine. The overall survival and progression-free survival of vinblastine-treated dogs were higher compared to tyrosine kinase inhibitors-treated dogs. Dogs with mutated KIT treated with tyrosine kinase inhibitors have longer overall survival and progression-free survival compared to those treated with vinblastine. It is important to consider the limitation of the study which should temper the interpretation of the results, videlicet, the extracted data lacked sample standardization and included variables such as animal characteristics, mutation detection methods, tumor characteristics, and treatment types which may have influenced the outcome of the study.

Systematic review registration

https://osf.io/, identifier: 10.17605/OSF.IO/WYPN4.

Intercellular interactions between mast cells and stromal fibroblasts obtained from canine cutaneous mast cell tumours

Mast cell tumours (MCTs) are the most frequent malignant skin neoplasm in dogs. Due to the difficulty in purifying large numbers of canine neoplastic mast cells, relatively little is known about their properties. A reproducible in vitro model is needed to increase the understanding about the phenotype and functional properties of neoplastic mast cells. In the present study, we describe the establishment of primary cocultures of neoplastic mast cells from canine cutaneous MCTs and cancer-associated fibroblasts. We confirmed the inability of canine neoplastic mast cells to remain viable for long periods in vitro without the addition of growth factors or in vivo passages in mice. Using a transwell system, we observed that mast cell viability was significantly higher when there is cell-to-cell contact in comparison to non-physical contact conditions and that mast cell viability was significantly higher in high-grade than in low-grade derived primary cultures. Moreover, the use of conditioned medium from co-cultured cells led to a significantly higher tumoral mast cell viability when in monoculture. Signalling mechanisms involved in these interactions might be attractive therapeutic targets to block canine MCT progression and deserve more in-depth investigations.

Panaxynol attenuates CUMS-induced anxiety and depressive-like behaviors via regulating neurotransmitters, synapses and the HPA axis in mice

Panaxynol (PAL, also called falcarinol) is widely found in plants of the Umbelliferae family, among which carrots are rich in PAL, so it is proved to be edible. PAL has neuroprotective effects and other pharmacological activities. This study aimed to explore the effects and mechanisms of action of PAL on chronic unpredictable mild stress (CUMS)-induced anxiety and depression in mice. The effects of PAL on behavioral activities in mice were first assessed by a CUMS-induced depression model. The secretion levels of monoamine neurotransmitters and hypothalamic-pituitary-adrenal (HPA) axis-related hormones were measured by ELISA. Western blotting was used to analyze the expression of glucocorticoid receptor (GR), glutamate receptor 1 (GluR1) and synapse-associated protein in the hippocampus. The behavioral experiment results showed that PAL can improve exploratory behavior and activities in mice. Meanwhile, PAL can significantly activate the release of 5-HT/5-HIAA and DA/HVA in the hippocampus. It inhibits the expression of adrenocorticotropic hormone (ACTH), corticosterone (CORT) and corticotrophin-releasing hormone (CRH) in serum and the hypothalamus. The contents of GR, glutamate receptor 1 (GluR1), postsynaptic density-95 (PSD95) and synapsin I protein in the hippocampus significantly increased. Studies have found that PAL can inhibit the hyperfunction of the HPA axis, which may be achieved by regulating HPA axis hormones and GR. Meanwhile, PAL promotes the release of 5-HT and DA in the hippocampus and improves synaptic plasticity in the hippocampus, allowing neurotransmitters to function more effectively. Therefore, PAL may improve anxiety and depression-like effects in mice through the abovementioned effects.

The phosphoinositide 3-kinase pathway is crucial for the growth of canine mast cell tumors

Mast cell tumors (MCTs) are the most common tumors in dogs, accounting for 16-21% of cutaneous tumors. Although several small molecule inhibitors, including imatinib mesylate, have been used for the treatment of MCTs, the response rate remains less than 50%. In this study, the effects of different selective signal inhibitors on MCT cell growth were evaluated using 4 different cell lines derived from dogs. We found that the phosphoinositide 3-kinase (PI3K) signaling pathway is crucial for the proliferation of MCT cells in the presence or absence of c-kit gene mutations. Here, we propose a novel therapeutic strategy to target the PI3K pathway for the treatment of canine MCTs.