PTEN Activation by DNA Damage Induces Protective Autophagy in Response to Cucurbitacin B in Hepatocellular Carcinoma Cells

الملخص EN

Cucurbitacin B (Cuc B), a natural product, induced both protective autophagy and DNA damage mediated by ROS while the detailed mechanisms remain unclear.

This study explored the mechanism of Cuc B-induced DNA damage and autophagy.

Cuc B decreased cell viability in concentration- and time-dependent manners.

Cuc B caused long comet tails and increased expression of γ-H2AX, phosphorylation of ATM/ATR, and Chk1/Chk2.

Cuc B induced autophagy as evidenced by monodansylcadaverine (MDC) staining, increased expression of LC3II, phosphorylated ULK1, and decreased expression of phosphorylated AKT, mTOR.

Cuc B induced apoptosis mediated by Bcl-2 family proteins and caspase activation.

Furthermore, Cuc B induced ROS formation, which was inhibited by N-acetyl-L-cysteine (NAC).

NAC pretreatment dramatically reversed Cuc B-induced DNA damage, autophagy, and apoptosis.

Cuc B-induced apoptosis was reversed by NAC but enhanced by 3-methyladenine (3-MA), chloroquine (CQ), and silencing phosphatase and tensin homolog (PTEN).

3-MA and CQ showed no effect on Cuc B-induced DNA damage.

In addition, Cuc B increased PTEN phosphorylation and silence PTEN restored Cuc B-induced autophagic protein expressions without affecting DNA damage.

In summary, Cuc B induced DNA damage, apoptosis, and protective autophagy mediated by ROS.

PTEN activation in response to DNA damage bridged DNA damage and prosurvival autophagy.