Inhibition of PI3K/Akt/mTOR signaling pathway enhances the sensitivity of the SKOV3/DDP ovarian cancer cell line to cisplatin in vitro

Abstract

The activation of the PI3K/AKT/mTOR pathway plays a key role in ovarian cancer tumorigenesis, progression and chemotherapy resistance. This study aimed to explore the possible mechanism that PI-103, a dual inhibitor of phosphatidylinositide 3-kinase and mTOR, enhances the sensitivity of SKOV3/DDP ovarian cancer cell line to cisplatin chemotherapy. The results showed that PI-103 could significantly increase the sensitivity of SKVO3/DDP cells to cisplatin through inhibiting the activation of PI3K/Akt/mTOR signaling pathway and inducing cell cycle arrest and apoptosis.

Keywords: PI3K/AKT/mTOR; cisplatin; ovarian cancer.

Figure 1

PI-103 inhibits SKOV3 and SKOV3/DDP proliferation. The inhibition rates of SKOV3 and SKOV3/DDP cells treated with PI-103 were assessed using CCK8 assay. The inhibition rate increased with the elevated concentration of PI-103. The growth inhibition rate was obviously increased when the concentration >0.35 mg/L. Treated with 0.35 mg/L PI-103, the inhibition rates of SKOV3 were 17.79%, 28.24%, 32.68% at 24, 48, 72 h, and those of SKOV3/DDP were 15.82%, 25.48%, 32.53% at 24, 48, 72 h.

Figure 2

The difference of IC50s of cisplatin for SKOV3 and SKOV3/DDP cells. The IC50s of cisplatin for SKOV3 and SKOV3/DDP cells were assessed by CCK8 assay. The inhibition rate is lower in SKOV3/DDP cells than in SKOV3 cells. The IC50s of DDP for SKOV3 and SKOV3/DDP cells were 3.31 and 13.96 mg/L, respectively.

Figure 3

PI-103 significantly increase the sensitive of SKOV3/DDP cells to cisplatin. The IC50s of cisplatin for SKOV3 and SKOV3/DDP cells treated with different concentration of PI-103 were assessed using CCK8 assay. The growth inhibition rates of SKOV3 and SKOV3/DDP were increased along with the increased concentration of PI-103 (A,B) and the IC50s were decreased (C,D).

Figure 4

PI-103 and cisplatin blocks cell cycle progress and increase apoptosis in SKOV3 and SKOV3/DDP cells. The influence of PI-103 and cisplatin on cell cycle, apoptosis was assessed by flow cytometry. PI-103 could increase the DNA content of G0/G1 in SKOV3 and SKOV3/DDP cells and the combination of PI-103 + cisplatin further increased the DNA content of G0/G1 in SKOV3 and SKOV3/DDP cells (A,B). In addition, the combination PI-103 + DDP could further increase the apoptosis rate (A,C).

Figure 5

PI-103 could inhibit the expression of cyclin D1 and increase the expression of p21, cl-caspase-3 in SKOV3/DDP. The protein level of cyclin D1, p21 and cleaved caspase-3 in SKOV3 and SKOV3/DDP cells treated with or without PI-103 and DDP were detected by western blot. PI-103 significantly decreased the protein level of cyclin-D1 and increased the level of p21, cleaved caspase-3 in SKOV3 and SKOV3/DDP cells, and cisplatin did the same in SKOV3/DDP. The combination showed better effects in SKOV3 and SKOV3/DDP cells (*P<0.05, ^#P<0.01).

Figure 6

PI-103 inhibits PI3K/Akt and mTOR signaling in SKOV3 and SKOV3/DDP. The protein level of phospho-Akt and phospho-S6 in SKOV3 and SKOV3/DDP cells treated with PI-103 and cisplatin using Western blot. PI-103 could decrease p-Akt and p-rpS6 expressions in SKOV3 and SKOV3/DDP cells, while cisplatin could not. The combination of PI-103 + cisplatin further inhibits the p-Akt and p-rpS6 expression (*P<0.05, ^#P<0.01). There were no significant changes in the total protein of Akt and rpS6.