Exendin-4 Induces Cytotoxic Autophagy in Two Ovarian Cancer Cell Lines through Inhibition of Mtorc1 Mediated by Activation of AMPK and Suppression of Akt

Badi, Rehab M.; Khaleel, E. F.; El-Bidawy, M. H.; Satti, H. H.; Mostafa, D. G.

doi:10.14712/fb2020066050186

Folia Biologica > Archive > 2020, Vol. 66 > Issue 5-6 > Exendin-4 Induces Cytotoxic Autophagy in…

Fol. Biol. 2020, 66, 186-203

https://doi.org/10.14712/fb2020066050186

Exendin-4 Induces Cytotoxic Autophagy in Two Ovarian Cancer Cell Lines through Inhibition of Mtorc1 Mediated by Activation of AMPK and Suppression of Akt

Rehab M. Badi^1,2, E. F. Khaleel^1,3, M. H. El-Bidawy^3,4, H. H. Satti^5,6, D. G. Mostafa^1,7

¹Department of Physiology, College of Medicine, King Khalid University, Abha, Saudi Arabia
²Department of Physiology, Faculty of Medicine, University of Khartoum, Khartoum, Sudan
³Department of Medical Physiology, Faculty of Medicine, Cairo University, Cairo, Egypt
⁴Department of BMS, Division of Physiology, College of Medicine, Prince Sattam Ibn Abdulaziz University, Al-Kharj, Saudi Arabia
⁵Department of Pathology, College of Medicine, King Khalid University, Abha, Saudi Arabia
⁶Department of Pathology, Faculty of Medicine, University of Khartoum, Khartoum, Sudan
⁷Department of Medical Physiology, Faculty of Medicine, Assiut University, Assiut, Egypt

Received May 2020
Accepted October 2020

Activation of autophagy suppresses ovarian cancer (OC). This in vitro study investigated whether the anti-tumour effect of exendin-4 against OC involves modulation of autophagy and figured out the possible mechanisms of action. SKOV-3 and OVCAR-3 cells (1 × 10⁵/ml) were cultured in DMEM medium and treated with exendin-4 in the presence or absence of chloroquine (CQ), an autophagy inhibitor. In some cases, cells were also treated with exendin- 4 with or without pre-treatment with compound C (CC), an AMPK inhibitor, or insulin-like growth factor (IGF-1), a PI3K/Akt activator. Exendin-4 increased expression of beclin-1 and LC3I/II, suppressed expression of p62, reduced cell survival, migration, and invasion, and increased cell apoptosis and LDH release in both SKOV-3 and OVCAR-3 cells. Besides, exendin-4 reduced phosphorylation of mTORC1, 6SK, 4E-BP1, and Akt but increased phosphorylation of AMPK in both cell lines. These effects were associated with down-regulation of Bcl-2, suppression of nuclear phosphorylation of NF-κB p65, and increased expression of Bax and cleaved caspases 3/8. Chloroquine completely prevented the inhibitory effects of exendin-4 on the cell survival, Bcl-2, NF-κB, and cell invasiveness and abolished its stimulation of cell apoptosis and LDH release. Moreover, only the combined treatment with IGF-1 and CC completely abolished the observed effect of exendin-4 on the expression of beclin-1, LC3I/II, p62, as well as on cell survival, apoptosis, and LDH release. Exendin-4 exhibits a potent anti-tumour cytotoxic effect in SKOV-3 and OVCAR-3 cells by activating the markers of autophagy, mediated by activation of AMPK and inhibition of Akt.

Keywords

Exendin-4, ovarian cancer, autophagy, AMPK, PI3K, Akt, mTORC1.

Funding

This work was fully funded by the Deanship of Scientific Research, King Khalid University through the General Research Projects Funding Program (Grant number 127/40).