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KATP channels regulate mitogenically induced proliferation in primary rat hepatocytes and human liver cell lines.
H Malhi1, A N Irani, P Rajvanshi
1Marion Bessin Liver Research Center, the Cancer Research Center, and the Departments of Medicine and Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Abstract:
To determine whether K(ATP) channels control liver growth, we used primary rat hepatocytes and several human cancer cell lines for assays. K(ATP) channel openers (minoxidil, cromakalim, and pinacidil) increased cellular DNA synthesis, whereas K(ATP) channel blockers (quinidine and glibenclamide) attenuated DNA synthesis. The channel inhibitor glibenclamide decreased the clonogenicity of HepG2 cells without inducing cytotoxicity or apoptosis. To demonstrate the specificity of drugs for K(+) channels, whole-cell patch-clamp recordings were made. Hepatocytes revealed K(+) currents with K(ATP) channel properties. These K(+) currents were augmented by minoxidil and pinacidil and attenuated by glibenclamide as well as tetraethylammonium, in agreement with established responses of K(ATP) channels. Reverse transcription of total cellular RNA followed by polymerase chain reaction showed expression of K(ATP) channel-specific subunits in rat hepatocytes and human liver cell lines. Calcium fluxes were unperturbed in glibenclamide-treated HepG2 cells and primary rat hepatocytes following induction with ATP and hepatocyte growth factor, respectively, suggesting that the effect of K(ATP) channel activity upon hepatocyte proliferation was not simply due to indirect modulation of intracellular calcium. The regulation of mitogen-related hepatocyte proliferation by K(ATP) channels advances our insights into liver growth control. The findings have implications in mechanisms concerning liver development, regeneration, and oncogenesis.
Insights
ATP-sensitive potassium (KATP) channels regulate liver growth by controlling hepatocyte DNA synthesis and proliferation. Blocking these channels inhibits liver cell growth, offering insights into liver development and cancer.
Area of Science:
- * Molecular Biology
- * Cell Biology
- * Physiology
Background:
- * Liver growth and regeneration are complex processes.
- * ATP-sensitive potassium (KATP) channels are implicated in various cellular functions.
- * The role of KATP channels in liver growth control remains largely unexplored.
Purpose of the Study:
- * To investigate the role of KATP channels in regulating liver growth.
- * To determine if KATP channel activity influences hepatocyte proliferation and DNA synthesis.
Main Methods:
- * Assays using primary rat hepatocytes and human liver cancer cell lines.
- * Application of KATP channel openers (minoxidil, cromakalim, pinacidil) and blockers (quinidine, glibenclamide).
- * Whole-cell patch-clamp recordings, reverse transcription, and polymerase chain reaction (PCR) for gene expression analysis.
- * Measurement of calcium fluxes to assess indirect effects.
Main Results:
- * KATP channel openers significantly increased hepatocyte DNA synthesis.
- * KATP channel blockers attenuated DNA synthesis and decreased HepG2 cell clonogenicity without inducing toxicity.
- * Patch-clamp recordings confirmed KATP channel activity in hepatocytes, modulated by specific drugs.
- * PCR analysis revealed expression of KATP channel subunits in hepatocytes and liver cell lines.
- * Calcium fluxes remained unaffected, indicating KATP channel's direct role in proliferation.
Conclusions:
- * KATP channels play a crucial role in controlling liver growth and hepatocyte proliferation.
- * Modulation of KATP channels offers a potential mechanism for regulating liver development, regeneration, and oncogenesis.
- * Findings advance the understanding of molecular mechanisms underlying liver growth control.