Melatonin Overcomes Cancer Multidrug Resistance by Downregulating ABCB1 Expression and Modulating Mitochondrial...

Area of Science:

• Oncology
• Biochemistry
• Mitochondrial Biology

Background:

• Multidrug resistance (MDR) is a significant obstacle in cancer chemotherapy.
• Overexpression of ATP-binding cassette (ABC) transporters, like ABCB1, is a key driver of MDR.
• Novel strategies are crucial to overcome resistance mediated by ABC transporters.

Purpose of the Study:

• To investigate the mechanisms by which melatonin overcomes ABCB1-mediated MDR in cancer cells.
• To elucidate the role of mitochondrial function in melatonin's MDR-reversing effects.
• To evaluate melatonin's potential as an adjuvant therapy against chemoresistance.

Main Methods:

• Assessed melatonin's effects on head and neck squamous cell carcinoma (CAL 27, SCC-9) and breast cancer (MCF-7) cell lines overexpressing ABCB1.
• Analyzed melatonin's impact on mitochondrial function, reactive oxygen species (ROS) production, and ABCB1 expression.
• Evaluated melatonin's efficacy in a CAL 27 xenograft mouse model.

Main Results:

• Melatonin treatment induced mitochondrial ROS production, weakening chemoresistance.
• ROS generation led to NADH oxidation to NAD+, limiting ATP availability for efflux pumps.
• Melatonin decreased mitochondrial localization near the nucleus, downregulated ABCB1 expression, and reduced tumor volume in vivo.

Conclusions:

• Melatonin enhances chemosensitivity in ABCB1-overexpressing cancer cells by modulating mitochondrial metabolism and redox balance.
• Melatonin's ability to downregulate ABCB1 expression contributes to overcoming MDR.
• Melatonin shows promise as an adjuvant therapy to combat multidrug resistance in cancer treatment.