SIRT6 Depletion Sensitizes Human Hepatoma Cells to Chemotherapeutics by Downregulating MDR1 Expression

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Hepatocellular carcinoma (HCC) treatment is challenged by multidrug resistance (MDR).
• Overexpression of MDR1 is a key mechanism contributing to MDR in HCC.
• SIRT6's role in HCC MDR remains largely unexplored.

Purpose of the Study:

• To investigate the function of SIRT6 in HCC MDR.
• To elucidate the molecular mechanism by which SIRT6 influences MDR in HCC.
• To identify potential therapeutic targets for overcoming MDR in HCC.

Main Methods:

• Utilized two HCC cell lines treated with chemotherapeutic agents (doxorubicin, cisplatin, sorafenib).
• Assessed changes in SIRT6 and MDR1 expression (mRNA and protein) via quantitative PCR and Western blotting.
• Investigated the effect of SIRT6 depletion on cell viability, apoptosis, and MDR1 transcription using knockdown techniques and promoter assays.
• Examined the role of CCAAT/enhancer binding protein β (C/EBPβ) in mediating SIRT6's effect on MDR1.

Main Results:

• Chemotherapeutic agents increased SIRT6 levels in HCC cells.
• SIRT6 depletion decreased cell viability and increased apoptosis upon chemotherapy treatment.
• SIRT6 depletion reduced MDR1 transcription and protein levels by suppressing C/EBPβ.
• Forced MDR1 expression reversed the increased apoptosis in SIRT6-depleted HCC cells.

Conclusions:

• SIRT6 depletion enhances chemosensitivity in HCC by downregulating MDR1 expression via suppression of C/EBPβ.
• SIRT6 acts as a transcriptional activator of MDR1 in HCC cells.
• SIRT6 represents a potential novel therapeutic target for improving chemosensitivity in hepatocellular carcinoma.