Severe degranulation of mesenteric mast cells in an experimental rat mammary tumor model.

Background/aim: Breast cancers are one of the most common cancers in women and are responsible for many deaths worldwide. Mast cells are inflammatory cells. Their role in cancers is controversial, and there is limited data on systemic mast cell activation in cancer cases. This study aimed to evaluate systemic mast cell activation in an experimentally induced rat model of breast cancer.

Materials and methods: Sprague Dawley female rats were divided into control (n = 6) and mammary tumor (n = 12) groups. In the tumor group, 20 mg 7,12-dimethylbenz[a]anthracene (DMBA) dissolved in 1 mL cottonseed oil was administered intragastrically by gavage, and the rats were followed daily until their mammary tumors reached 3 cm in diameter. The control group received only cottonseed oil. Paraffin sections obtained from the mammary tumor tissue were subjected to hematoxylin-eosin, toluidine blue staining, and proliferating cell nuclear antigen (PCNA) immunohistochemistry. Mesenteric tissues from each subject were also stained with toluidine blue. The number and activation status of mast cells in mammary tumors and mesenteric tissues were evaluated.

Results: Toluidine blue staining showed that activated mast cells were commonly found in tumor tissues. Based on the mesenteric tissue analysis, severe degranulation of the mesenteric mast cells was found in the tumor-induced groups compared to the control group.

Conclusion: This study demonstrated for the first time that systemic mast cell activation develops in both tumoral and mesenteric tissues in an experimental cancer model. However, it is not known at which stage of tumor development it occurs.