Effects of Gnidilatimonoein, from Daphne mucronata, on the plasma membrane glycoproteins in two cancerous cell lines

Abstract

Metastasis describes the ability of a tumor to invade normal tissue and generate secondary tumors at sites distant from the primary tumor. The mechanism responsible for the inhibition of tumor metastasis by different agents is at least partly associated with the ability to interfere with cellular functions such as adhesiveness, motility and invasiveness. Certainly effective treatment of metastasis requires a full understanding of the mechanisms underlying metastasis. Recently we have reported the anti-tumor and anti-metastatic potency of an alcoholic extract of D.mucronata (Thymeleaceae) using animal models. Additionally, we have also reported the effect of the crude extract and one of its active anti-tumor components Gnidilatimonoein, on cell-to-cell and cell-to-matrix adhesion. According to these data, the plant extract is capable of quenching the adhesion of cells to cells or the cells to the matrix by almost 80-85%. To get a better understanding of the mode of action of Gnidilatimonoein, we need to evaluate the effect (s) on the plasma membrane glycoproteins, which are believed to be involved in cell-to-cell communications and attachment to membranes. After labelling the cultured BHK-21 and Wehi-164 cells with [3H]-fucose for 24 hours, the cells were treated with a single pharmaceutical dose (1.2 micromolar) of genidilitimonoein. The cells were incubated at 37°C for another 24 hours. Then the cells we collected, washed, lysed and the plasma membrane were collected, extracted and hydrolyzed by protease digestion. The digested samples were analysed by gel filtration chromatography using Sephadex G50. The membrane glycoproteins of the plant treated and untreated cells were studied after metabolic labeling of the cells with [3H]-fucose followed by the isolation and chromatographic analyses of the labeled glycoproteins. According to our data, it became evident that the cell surface glycoproteins of the treated cells had smaller molecular weights compared to the untreated cancerous cell lines. Based on our observation, it may be concluded that D.mucronata crude extract and its active component, Gnidilatimonoein, are capable of modulating the glycosylation of the membrane glycoproteins. These modifications most certainly will affect the whole functions of a metastatic cell mainly its adhesion to different matrixes and its invasion capability to new sites. We will discuss the experimented details in this report.