Phd in MORPHOGENESIS AND TISSUE ENGINEERING

Thesis title: Role of muscarinic receptors in epithelial ovarian carcinoma (EOC)

Epithelial ovarian cancer (EOC) is one of the most common female cancer; it is more common in patients with elevated gonadotropins (FSH and LH), such as postmenopausal women. EOC arises from the ovarian surface epithelium (OSE), a continuous layer of cuboidal epithelial cells covering the surface of the ovary, which undergoes a process of injury-repair at each ovulation. In the ovary, a non-neuronal cholinergic system is present, and acetylcholine (ACh) is produced by granulosa cells and luteal cells. ACh contributes to physiological ovarian tissue remodeling by stimulation of cell proliferation and it is involved in local regulation of tissue rearrangements in the follicle and possibly in the formation of corpora lutea. A large percentage of ovarian tumor cell lines express muscarinic receptors: it has been seen that their expression is correlated with reduced survival of patients. This study is focused on the analysis of the involvement of muscarinic receptors in the progression of ovarian carcinoma. In the present work we have characterized the expression of muscarinic receptors in two human ovarian carcinoma cell lines (SKOV-3, TOV21-G) and in two immortalized ovarian surface epithelium cell lines (iOSE-120, iOSE-398). We observed that M4 is not expressed in all cell lines while the other muscarinic receptors are present, even though at different levels. We focused our attention on M2 muscarinic receptor and RT-PCR results showed that the level of M2 is higher in iOSE than in cancer cells. We investigated its role in the control of cell growth and survival: treatment with arecaidine propargyl ester hydrobromide (APE), a selective M2 agonist, decreases cell number in a dose and time dependent manner but it was evident that cancer cells are more resistant than iOSE, in particular TOV cell line. In the iOSE-120, we found a significant increase in the percentage of cell death, dose and time dependent, that well correlated with their lower rate of growth. On the contrary, in cancer cells, we observed significant levels of cell death only at the highest concentration of APE, where it is evident that SKOV-3 are more sensitive to the treatment than TOV21-G. Moreover, in cancer cells, APE treatment was able to delay the cell cycle progression. These results suggest that M2 receptor has a negative role on cell growth/vitality, therefore, its downregulation may favour tumor progression.