The significance of oxytocin in canine mammary tumours
Oxytocin is a hormone which plays a crucial role in many reproductive and behavioural functions. It affects many organs and the classical peripheral targets are the mammary glands during lactation and uterus during labour. Oxytocin receptors have recently been described in a variety of normal tissues and primary cell cultures, but also in neoplastic tissues and established neoplastic cell lines, as breast cancer cell lines. The signalling pathways and biological effects of the oxytocin/oxytocin receptor system seem to depend on species, type of tissue, physiological versus neoplastic state and receptor location within the cell membrane.The aim of this project was to find out if the cell proliferation in the canine mammary carcinoma cell line CMT-U27 was affected upon stimulation of oxytocin, and to investigate the presence of oxytocin receptors in these cells. The cell proliferation was examined by using an ELISA-kit, where the absorbance measured is relative to the amount of living cells. Immunocytochemistry was used to detect possible oxytocin receptors.The results showed that there was significant inhibition of the cell proliferation with the addition of oxytocin. In three different assays at least one cell concentration showed significant inhibition of the cell growth. The immunocytochemistry analysis showed the presence of oxytocin receptors and based on the location of the receptors it seemed to be at least two groups within the cell line. Some of the cells show marked staining in the nuclear membrane and some seemed to be unstained or had weak staining in the cell membrane or cytoplasm.Since the location of the oxytocin receptors show that they have been activated, further studies can find out which of the cells that produce oxytocin, and if the possible synthesis leads to paracrine or autocrine stimulation.