Commercial Crude Extract Of Curcuma Longa Regulates WNT-_-Catenin Activity In HEPG2 Cells

Andrés CARDONA, Instituto Tecnológico Metropolitano , Colombia

1 Grupo de Investigación e Innovación Biomédica-GI2B, Facultad de Ciencias Exactas y Aplicadas, Instituto Tecnológico Metropolitano (ITM), Medellín, Colombia
2 Grupo Genética Regeneración y Cáncer-GRC, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia (UdeA), Medellín, Colombia

Introduction: Deregulation of Wnt/β-catenin signaling plays an important role in development of several types of cancer, including hepatocellular carcinoma. Curcumin, the major constituent of Curcuma longa has been shown to modulate the activation of Wnt/β-catenin pathway and diminishes methylation levels of extracellular Wnt antagonists. Likewise, the complete spice (curcuma) displayed hepatoprotective effects, however there are few studies performed with curcuma complete extract in liver cancer.

Purpose: To determine the effect of a commercial crude extract of Curcuma longa in the sub-cellular localization and transcriptional activity of β-catenin in HepG2 cells.

Methods: Curcuma extract was obtained by dissolving a commercial curcuma powder in dimethyl sulfoxide (DMSO). On a daily basis, HepG2 cell line was treated with a non-cytotoxic dose of 250 µg/ml of curcuma extract or 0.25% of DMSO. After 96 hours of treatment, cells were fixed and stained with a primary antibody against β-catenin (BD Transduction Laboratories), Alexa fluor 488 (Life Technologies) as secondary antibody and then counterstained with Hoescht (Life Technologies); subsequently, the sub-cellular localization of β-catenin was evaluated by confocal microscopy. In order to determine β-catenin transcriptional activity, TOPFLASH and FOPFLASH plasmids (Upstate Biotechnology), containing wild-type and mutant TCF binding sites, respectively, were transfected to HepG2 cells to quantify the luciferase activities.

Results: Cells exposed to curcuma extract exhibited low nuclear and cytoplasmic levels of β-catenin in comparison with untreated cells. In addition, curcuma treatment reduced significantly the transcriptional activity of the Wnt/β-catenin pathway.

Conclusion: The results showed here suggest that crude extract of curcuma could regulate Wnt/β-catenin signaling pathway, even in HepG2 cells that has a regulatory domain deletion in one allele of CTNNB1 gene. These observations need further investigation to reveal the mechanisms involved in β-catenin regulation by complete extracts of Curcuma longa.

Founding source: ITM grant number P10242