Prevention of chemotherapy-induced damage to ovarian reserve by sphingosine-1-phosphate

Abstract

1097 Background: Chemotherapy agents such as cyclophosphamide (Cy) and doxorubicin (D) are known to compromise ovarian function. We have previously shown that these agents alter ovarian function by causing apoptotic death of primordial follicles and thereby causing diminishment of ovarian reserve (Cancer Research 2007; Aging 2011). While assisted reproduction techniques exist to preserve fertility there has been no proven approach to pharmacologic preservation of ovarian function. Sphingosine-1-Phosphate (S1P) is a naturally occurring ceramide-induced death pathway inhibitor. Here we investigated whether S1P can prevent Cy or D-induced apoptotic follicle death in mouse ovaries. Methods: Eight wk old NOD mice (n=23) were treated with Cy (75 mg/kg), Cy+S1P (200 μM), D (10 mg/kg), D+S1P or vehicle only (Control). S1P was administered via continuous infusion using a mini-osmotic pump beginning 3 hours prior to single dose chemotherapy injection for 72 hours. Ovaries were removed 72h later and serially sectioned, and stained with anti-caspase 3 (AC-3) antibody for the detection of apoptosis in primordial follicles. The ratio of apoptotic to total follicles was expressed as percentage in each group. Results: Both Cy and D resulted in significant increase in apoptotic follicle death compared to controls (48.2±11.6 vs. 28.2±8.9, p=0.016 and 46.4±5.4 vs. 24.8±5.2, p=0.004, respectively). Percentages of apoptotic follicles were similar between Cy and D-treated groups (48.2±11.6 vs. 46.4±5.4, P=NS) indicating that these agents were equally gonadotoxic. S1P treatment resulted in a significant decrease in the percentage of apoptotic follicles both in the Cy (25.6±3.5, P<0.011) and the D group (32.2±10.8, P< 0.013) compared to controls. In the S1P-treated groups, the percentages of apoptotic follicles were similar to those in untreated controls indicating that S1P completely blocked Cy and D-induced apoptotic follicle death. Conclusions: S1P can block apoptotic follicle death induced by highly cytotoxics agents. In addition, we showed that S1P can block follicle death by chemotherapy agents that act through different molecular mechanisms. If targeted delivery systems can be developed, S1P may hold significant promise in preserving fertility by pharmacological means.