**2. Methods**

#### **2.1 Ovarian cancer cell culture**

The human ovarian cell line (TOV-21G) was cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum (FBS) and 5% CO2 at 37°C. (i) Ovarian cell line used here was TOV-21G, which was obtained from Keibai Academy of Science (Nanjing, China) [18]. (ii) RPMI 1640 was used without glutamine, lysine, and arginine. (iii) FBS was brought from Gibco® Certified Thermo Fisher Scientific. (iv) The growing states of TOV-21G were observed, and the medium was changed in every 2 days.

#### **2.2 SILAC medium preparation and labeling**

SILAC "light" or "heavy" labeling growing medium (Thermo Fisher Scientific, US) was used to culture TOV-21G cells for 10 passages, to ensure a high level of stable isotope replacing original amino acids [8]. (i) "Light" labeled amino acids: 50 mg L-arginine HCl (Arg0), 50 mg L-lysine HCl (Lys0). "Heavy" labeled amino acids: 50 mg L-arginine-13C6,15N4 HCl (Arg10), 50 mg L-lysine-13C6,15N2 HCl (Lys8). (ii) A total of 1 L RPMI 1640 without glutamine, lysine, and arginine. (iii) For SILAC experiments, 50 mg Arg0 and 50 mg Lys0 ("light" labeling reagent) were added into 500 mL RPMI 1640 medium to form SILAC "light" labeling growing medium. A total of 50 mg Arg10 and 50 mg Lys8 ("heavy" labeling reagent) were added to 500 mL RPMI 1640 medium to form SILAC "heavy" labeling growing medium. (iv) The growing states of TOV-21G were observed, and the medium was changed in every 2 days. TOV-21G cells were cultured and passaged for 10 generations in 10-cm culture flasks.
