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Identification of mitochondrial F(1)F(0)-ATP synthase interacting with galectin-3 in colon cancer cells
Duck-Woo Kim1, Kyung Hee Kim, Byong Chul Yoo
1Department of Surgery, Seoul National University College of Medicine, Chongno-Gu, Seoul, Korea.
Abstract:
To evaluate the effect of galectin-3 in cell cycle regulation of colon cancer cells, we looked for binding molecules interacting with galectin-3 and examined the changes in cell cycle by suppressing galectin-3 and the binding molecule. To identify target molecules interacting with galectin-3, we analyzed immunoprecipitate of the anti-galectin-3 antibody obtained from human colon cancer cell line, using matrix-assisted laser desorption ionization-mass spectrometry. We validated subcellular localization of galectin-3 and ATP synthase identified, and ATP synthase activity was determined in the presence of galectin-3. Cell cycle regulation was monitored after galectin-3 siRNA transfection. ATP synthase b-subunit was identified in immunoprecipitate of the anti-galectin-3 antibody. Galectin-3 and ATP synthase were co-isolated in the inner membrane vesicles of mitochondria. Galectin-3 has an inhibitory activity against ATP synthase, and intracellular ATP content showed increasing tendency after galectin-3 suppression. Suppression of galectin-3 resulted in G0/G1 progression of human colon cancer cells arrested at S, S/G2 and G2/M phase in the presence of doxorubicin, and etoposide or nocodazole, respectively. Compared to cells in which ATP synthase d-subunit was suppressed alone, sub-G1 fraction caused by etoposide or nocodazole was decreased in cells with galectin-3 suppression alone. In conclusion, galectin-3 co-localized with ATP synthase in the inner membrane of mitochondria and has an inhibitory effect on ATP synthase in human colon cancer cells. In the presence of cell cycle synchronizing drugs, doxorubicin, etoposide, or nocodazole, suppression of galectin-3 induced cell cycle progression to G0/G1 phase.
Insights
Galectin-3 interacts with ATP synthase in colon cancer mitochondria, inhibiting its activity. Suppressing galectin-3 promotes cell cycle progression, offering potential therapeutic strategies for colon cancer.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Biology
Background:
- Galectin-3 is implicated in various cellular processes, including cancer progression.
- Understanding galectin-3's role in colon cancer cell cycle regulation is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the interaction between galectin-3 and its binding molecules in colon cancer cells.
- To determine the effect of galectin-3 and its binding partners on cell cycle regulation.
- To explore the functional consequences of galectin-3 suppression on colon cancer cell proliferation.
Main Methods:
- Identification of galectin-3 binding molecules using immunoprecipitation and mass spectrometry.
- Validation of subcellular localization of galectin-3 and ATP synthase.
- Assessment of ATP synthase activity and intracellular ATP content.
- Monitoring of cell cycle progression after galectin-3 suppression via siRNA transfection.
- Analysis of cell cycle distribution in the presence of chemotherapeutic agents.
Main Results:
- ATP synthase beta-subunit was identified as a binding molecule for galectin-3.
- Galectin-3 and ATP synthase were co-localized in mitochondrial inner membrane vesicles.
- Galectin-3 exhibited inhibitory activity against ATP synthase, with suppression leading to increased intracellular ATP.
- Suppression of galectin-3 promoted G0/G1 phase progression in colon cancer cells arrested by doxorubicin, etoposide, or nocodazole.
- Reduced sub-G1 fraction was observed upon galectin-3 suppression compared to ATP synthase delta-subunit suppression.
Conclusions:
- Galectin-3 co-localizes with ATP synthase in mitochondria and inhibits its activity in human colon cancer cells.
- Galectin-3 suppression facilitates cell cycle progression from arrested phases to G0/G1.
- These findings highlight a novel mechanism involving galectin-3 and ATP synthase in colon cancer cell cycle control.
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