Cuscuta reflexa roxb. and its pure compounds-induced micronuclei in plant cells and downregulation of EGFR expression in NCI-H460 Cell Line

ABSTRACT

Cuscuta reflexa Roxb. [Convolvulaceae] has medicinal applications used in treating wide range of diseases including cancer. The methanolic extract of C. reflexa Roxb. [MECR] grown on host Nerium oleander L.] and its pure compounds namely, odoroside H [1], neritaloside [2] and strospeside [3] were assessed for genotoxicity using mitotic meristematic root tip cells of Allium species [A. cepa and A. sativum] and meiotic pollen mother cells from Tradescantia pallida var purpurea. The effect of pure compounds were also evaluated in human non-small cell lung cancer cell line [NCI-H460] on tumor suppressor gene [p53] and epidermal growth factor receptor [EGFR] expression using agarose gel electrophoresis. The MECR between 0.1 and 1 mg/ml was ineffective in mitotically dividing cells, whereas in meiotic pollen mother cells, higher concentrations [5-20 mg/ml] caused significant induction of micronuclei [MN]. In both mitotic and meiotic cells, odoroside H and neritaloside induced significant rise in MN frequency, however, strospeside had no effect. The genotoxic potential in both cells was in the order of [1] = [2] > MECR > [3]. MECR and odoroside H [1] caused dose dependent growth inhibition in NCI-H460 cells with GI50 of 0.92 +/- 0.04 microg/ml and of 0.08+/-0.01 microg/ml, respectively. The antiproliferative action of MECR [1 microg/ml], odoroside H [1] [0.14 microM], neritaloside [2] [.16 microM] and strospeside [3] [0.5 microM] in comparison to control, significantly downregulated expression of epithelial growth factor receptor [EGFR] by two fold with no affect on p53 gene expression. This study clearly demonstrates that MECR is genotoxic at higher doses and should be taken into account if used for medicinal purposes. The mitotic cells of Allium species were more sensitive [2x] in MN formation than meiotic cells of T. pallida pu. Furthermore, MECR and pure compounds possesses antiproliferative activity against NCI-H460 cells that might be mediated through EGFR-dependent but p53-independent pathways?