Preventive Effects of Oxytocin and Oxytocin Receptor in Breast Cancer Pathogenesis

Abstract

Aim: Modifications of oxytocin (OT) concentration and OT receptor (OXTR) expression level have different effects on breast cancer-derived cells. This study was conducted to evaluate OT variation in breast cancer patients and to evaluate OXTR expression changes in breast cancer tissues. Methods: The plasma concentrations of OT in both breast cancer patients and healthy individuals’ samples were assessed. OXTR variations were then assessed in both cancerous and noncancerous breast tissues. Results: OT had an increase in breast cancer patients and expression of OXTR in contralateral breast was more than cancerous tissues. Conclusion: Despite the high levels of OT concentration in breast cancer patients, it seems that a lower expression of OXTR in cancerous tissues can be effective in the breast cancer progression.

The oxytocin receptor signalling system and breast cancer: a critical review

“…OT levels in the pituitary and blood also increased in a rat breast cancer model induced by N-methyl-nitrosourea (NMU)-treatment due to inhibition of insulin-regulated aminopeptidase (an oxytocinase) and decrease of catabolism of OT in the hypothalamus [57]. This is consistent with a human study, which observed higher OT plasma levels in breast cancer patients (n = 40) than in healthy individuals [58]. Higher OT plasma levels, however, do not mean higher OT levels in breast cancer tissue.…”

“…So far there exists only one study indicating that OTR expression in tumour tissues is lower (>11-fold at mRNA level and >2-fold at the protein level, n = 4) than in normal contralateral breast samples from the same individual. The authors of this study stated that a reduction of OTR expression in breast cancer could be effective in promoting cancer progression [58].…”

“…1a was adapted from [71]. [88], with OTR gene expression being 8.6-fold higher in breast tumour tissues of ER + patients (n = 27) than ER − patients (n = 10) [58].…”

“…In MCF-7 and T47D (ER + ) cell lines, 30 min of 10 nM E2 treatment yielded a 100-fold increase in the OTR mRNA expression [37]. However, the correlation between OTR expression and ER + breast tumours is not consistent among studies [58,68,88]. The increased OTR levels with E2 dominance indicate that there is a potential for these tissues to be sensitive to OTRmediated effects, including inhibition of tumour growth [131].…”

“…In humans, very few studies have indicated a relationship between OTR expression and other clinical variables (such as tumour size, biomarkers, metastasis or histological grade), except that OTR is more likely to be correlated with oestrogen receptor-positive (ER + ) breast tumours. For example, there were more samples diffusely expressing OTR (diffusely expressing was defined as that >80% cells were stained by IHC detection) in ER + samples (18 out of 32 ER + patients) than in ER-negative (ER − ) patients (7 out of 19 ER − patients) [ 88 ], with OTR gene expression being 8.6-fold higher in breast tumour tissues of ER + patients ( n = 27) than ER − patients ( n = 10) [ 58 ].…”