Targeting RuvBL1 disrupts mitochondrial metabolism and structure in hepatocellular carcinoma

Area of Science:

• Biochemistry
• Cell Biology
• Oncology

Background:

• RuvBL1 is an AAA+ ATPase involved in chromatin remodeling, DNA repair, ribosome biogenesis, mTOR signaling, and oncogenic transformation.
• RuvBL1 overexpression correlates with poor survival in hepatocellular carcinoma (HCC) patients.
• RuvBL1 is a key regulator of liver glucose metabolism.

Purpose of the Study:

• To investigate the metabolic function of RuvBL1 in HCC cells.
• To understand the role of RuvBL1 in mitochondrial metabolism and its potential as a therapeutic target in HCC.

Main Methods:

• Used non-transformed AML-12 cells, primary mouse hepatocytes, HCC cell lines, and RuvBL1hep-/- mice.
• Targeted RuvBL1 using RNAi and the inhibitor CB-6644.
• Assessed metabolomic profiling, mitochondrial functions (Seahorse analysis, ATP synthase activity), mitochondrial morphology, and membrane potential.
• Detected mitochondrial RuvBL1 localization using various microscopy techniques and Western blotting.
• Performed in silico analysis on human HCC and normal liver samples from TCGA and GTEx databases.

Main Results:

• Targeting RuvBL1 impairs mitochondria-centered metabolic processes, including amino acid metabolism, the TCA cycle, and oxidative phosphorylation (OXPHOS).
• Inhibition of RuvBL1/2 activity leads to loss of mitochondrial cristae integrity, hyperpolarization, and fragmentation.
• RuvBL1 was detected in proximity to mitochondrial ATP synthase, and its inhibition impairs Complex V activity.
• Higher RUVBL1 expression in human HCC correlates with gene signatures of mitochondrial oxidative phosphorylation and ATP synthase complex, and poorer patient outcome.

Conclusions:

• Targeting RuvBL1 impairs Complex V activity, disrupting mitochondrial metabolic functions and structural integrity.
• The mitochondrial functions of RuvBL1 present potential novel therapeutic strategies for hepatocellular carcinoma.
• RuvBL1's role in metabolic reprogramming and plasticity of HCC suggests it as a target for therapeutic approaches.