Combination Therapy with Betulinic Acid and TRAIL Increases ROS-Dependent Cytotoxicity and Inhibits PI3K/Akt...

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) therapy shows promise for cancer treatment but faces resistance, particularly in bladder cancer.
• Betulinic acid (BA) is a natural compound with known anticancer and chemosensitizing properties.

Purpose of the Study:

• To investigate if betulinic acid (BA) can sensitize TRAIL-resistant human bladder cancer cells to TRAIL-induced apoptosis.
• To elucidate the molecular mechanisms underlying the combination therapy's effects.

Main Methods:

• Combination treatment of TRAIL-resistant human bladder cancer cells with BA and TRAIL.
• Assessment of cytotoxicity and apoptosis induction.
• Measurement of reactive oxygen species (ROS) production.
• Analysis of apoptosis-related protein expression (Bax, Bcl-2, Bid cleavage).
• Evaluation of caspase activation, cytochrome c release, and mitochondrial membrane potential.
• Investigation of phosphoinositide 3-kinase (PI3K)/Akt signaling pathway activity.

Main Results:

• Combination treatment significantly increased cytotoxicity and apoptosis compared to single treatments.
• The combination therapy elevated ROS production, Bax expression, and Bid cleavage (tBid), while downregulating Bcl-2.
• Apoptosis was mediated by caspase activation (extrinsic and intrinsic pathways) and cytochrome c release.
• The treatment inhibited PI3K and Akt phosphorylation, an effect dependent on ROS and amplified by PI3K inhibition.

Conclusions:

• Betulinic acid (BA) sensitizes bladder cancer cells to TRAIL-induced apoptosis through ROS-dependent mechanisms.
• The combination therapy inhibits the PI3K/Akt signaling pathway, contributing to enhanced apoptosis.
• The BA and TRAIL combination holds potential for overcoming TRAIL resistance in human bladder cancer.