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Published on: September 18, 2013
Geranylated flavanone tomentodiplacone B inhibits proliferation of human monocytic leukaemia (THP-1) cells
Peter Kollár1, Tomáš Bárta, Veronika Závalová
1Department of Human Pharmacology and Toxicology, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic. kollarp@vfu.cz
Background And Purpose:
Paulownia tomentosa is a rich source of geranylated flavanones, some of which we have previously shown to have cytotoxic activity. To identify members of this class of compounds with cytostatic effects, we assessed the effects of the geranylated flavanone tomentodiplacone B (TOM B) on cell cycle progression and cell cycle regulatory pathways of THP-1 human monocytic leukaemia cells.
Experimental Approach:
Cell viability was measured by dye exclusion and proliferation by WST-1 assays; cell cycle was monitored by flow cytometry. Regulatory proteins were assessed by immunoprecipitation and kinase assays, and Western blotting.
Key Results:
Tomentodiplacone B had no effect during the first 24 h of cell growth at concentrations between 1 and 2.5 µM, but inhibited cell growth in a dose-dependent manner at concentrations of 5 µM or higher. Growth inhibition during the first 24 h of exposure to TOM B was not accompanied by cytotoxicity as cells were accumulated in G1 phase dose-dependently. This G1 phase accumulation was associated with down-regulation of cyclin-dependent kinase 2 activity and also protein levels of cyclins E1 and A2. However, key stress-related molecules (γ-H2AX, p53 and p21) were not induced, suggesting that TOM B acts by directly inhibiting the cyclin-dependent kinase 2 signalling pathway rather than initiating DNA damage or cellular stress.
Conclusions And Implications:
Our study provides the first evidence that TOM B directly inhibits proliferation of human monocytic leukaemia cells, and thus is a potential anticancer agent, preventing leukaemia cells from progressing from G1 phase into DNA synthesis.
Insights
Tomentodiplacone B, a geranylated flavanone, inhibits human monocytic leukaemia cell proliferation by blocking cell cycle progression at G1 phase. This compound shows potential as an anticancer agent by preventing DNA synthesis in leukaemia cells.
Area of Science:
- Natural Products Chemistry
- Cell Biology
- Pharmacology
Background:
- Paulownia tomentosa yields geranylated flavanones with known cytotoxic activity.
- Identifying cytostatic compounds from this class is of therapeutic interest.
Purpose of the Study:
- To investigate the cytostatic effects of tomentodiplacone B (TOM B) on THP-1 human monocytic leukaemia cells.
- To elucidate the impact of TOM B on cell cycle progression and regulatory pathways.
Main Methods:
- Cell viability and proliferation assays (dye exclusion, WST-1).
- Flow cytometry for cell cycle analysis.
- Immunoprecipitation, kinase assays, and Western blotting for protein analysis.
Main Results:
- Tomentodiplacone B inhibited THP-1 cell growth at concentrations ≥5 µM, with dose-dependent G1 phase accumulation.
- Growth inhibition was not cytotoxic and occurred without inducing key stress markers (γ-H2AX, p53, p21).
- TOM B down-regulated cyclin-dependent kinase 2 activity and protein levels of cyclins E1 and A2.
Conclusions:
- Tomentodiplacone B directly inhibits human monocytic leukaemia cell proliferation.
- TOM B acts by directly inhibiting the cyclin-dependent kinase 2 signalling pathway.
- TOM B is a potential anticancer agent preventing G1 to DNA synthesis progression in leukaemia cells.
