The Aracea Anthurium schlechtendalii and Syngonium podophyllum are traditional remedies for the treatment of severe and chronic inflammatory conditions. We cross-examined these plants regarding their anti-neoplastic properties, because several anti-inflammatory molecular targets are common for both pathologic conditions due to similar signalling pathways. Two malignant cell lines, HL-60 and MCF-7, were treated with increasing concentrations of plant extracts of increasing polarity. The potential of the extracts to inhibit the cell cycle and to induce cell death was investigated, because these are relevant endpoints to assess the anti-cancer potential in vitro and the protein expression and cell cycle distribution upon exposure to the strongest extract was analysed. Extracts from S. podophyllum were rather ineffective, but the freeze-dried (but not air-dried) roots of A. schlechtendalii exhibited strong growth inhibitory and apoptosis-inducing properties. In HL-60 cells 50% proliferation inhibition was achieved by 1.7 µg dichloromethane extract/ml medium and correlated with the activation of Chk2, down-regulation of Cdc25A, suppression of cyclin D1 level, and transient induction of p21. This extract efficiently triggered apoptosis, which was confirmed by caspase 3 activation. The polymerisation of α-tubulin and its subsequent degradation that depleted the cells from the G2/M contributed to apoptosis induction, because proper spindle-formation during mitosis is mandatory for survival. In conclusion, we demonstrated that A. schlechtendalii root extract specifically targeted carcinogenic mechanisms, because Cdc25A and cyclin D1 are oncogenes that are frequently overexpressed in a variety of cancer entities and further, this extract affected microtubule function reminiscent of taxol.

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