[Expression of Notch1, Jagged1 and NICD in epithelial ovarian carcinomas and a preliminary study on the activity of gamma-secretase in epithelial ovarian carcinoma cell lines].

OBJECTIVE

To study the expression of Notch1, Jagged1 and Notch intracellular domain (NICD)in epithelial ovarian carcinoma tissues and analyze the clinical significance. To explore the activity of γ-secretase in epithelial ovarian carcinoma cell line SKOV3 and the effect of N-[N-(3, 5-dil uorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), a γ-secretase inhibitor on the activity of γ-secretase in SKOV3.

METHODS

Immunohistochemistry staining method was performed in 43 patients with epithelial ovarian carcinoma and 11 patients with benign epithelial ovarian tumor to detect the expression of Notch1, Jagged1 and NICD. The differences of expressionof Notch1, Jagged1 and NICD between malignant and benign ovarian tumors was compared and alsoanalyzed the correlation with clinicopathological parameters of ovarian carcinoma. Human serous ovarian cancer cell line SKOV3 and immortalized nontumorigenic ovarian epithelial cell line T29 were incubated in vitro. The activities of γ-secretase in SKOV3 and T29 with dimethyl sulfoxide (DMSO) and DAPT were detected respectively by Gal4-VP16/UAS and dual luciferase reporter assay system.

RESULTS

(1) The immunohistochemical composite scores (ICS) of Notch1 in epithelial ovarian carcinoma (6.7 ± 2.2) were not significantly different with those in benign epithelial ovarian tumor (5.4 ± 2.7, P = 0.153), while the ICS of Jagged1 and NICD in epithelial ovarian carcinoma (5.3 ± 2.4, 5.3 ± 2.3)were higher than those in benign epithelial ovarian tumor (1.6 ± 1.4, 3.1 ± 1.7; all P < 0.01). The expression of Notch1, Jagged1 and NICD had no correlation with patients' aged, history of carcinoma, ascites, the level of serum CA125, maximum length of ovarian tumor, Federation International of Gynecology and Obstetrics (FIGO) stage, grade and pathology subtypes (all P > 0.05). The hazard ratio between the high expression of Notch1, Jagged1, or NICD and the moderate to low expression of Notch1, Jagged1, or NICD, and Jagged1 were 0.771, 1.648 and 1.316, respectively (all P > 0.05). The 5-year survival rate and median survival time between the high expression of Notch, Jagged1 or NICD in subgroup and moderate to low expression in subgroup were of no difference (all P > 0.05). The activity of γ-secretase in SKOV3 was significantly higher than that in T29([ 12.2 ± 1.4)%, P = 0.019]. (2) After DAPT treated, the relative activity of γ-secretase in SKOV3 (50 µmol/L) was declined from (100.0 ± 5.3)% to(6.6 ± 0.8)% (P = 0.001).

CONCLUSIONS

Jagged1 and NICD in Notch1 pathway may play a key role in the occurrence of ovarian carcinoma. The activity of γ-secretase in epithelial ovarian carcinoma was higher than that in ovarian epithelial cell which suggest that DAPT, γ-secretase inhibitor, may become the target of ovarian carcinoma treatment.