ABSTRACT
;Aim To study the effect of exopolysaccharide from Trichoderma pseudokoningii (EPS) on the proliferation and apoptosis of human colon cancer cell line HCT116. Methods The proliferation of HCT116 cells treated with EPS was examined by CCK-8 assay. The effect of EPS on the clone formation of HCT116 cells was detected by crystal violet staining. Cell apoptotic rate was determined by flow cytometry. The changes of mitochondrial membrane potential were observed by JC-1. The expressions of apoptosis-related proteins Bcl-2 and Bax were analyzed by Western blot, and caspase-9, caspase-8 and caspase-3 expressions were detected by the kit. Results EPS dose- and time-dependently inhibited the proliferation of the HCT116 cells in the range of 0 -800 mg • L " 1 . With increase of EPS concentration, the colony-formation ability of HCT116 cells decreased; the proportion of apoptotic cells increased and mitochondrial membrane potential decreased; the expression of Bcl-2 protein decreased, while the expression of Bax protein increased; the ratio of Bcl-2/Bax decreased gradually; caspase-9, caspase-8 and caspase-3 activities significantly increased. Conclusions EPS can inhibit proliferation of HCT116 and induce its apoptosis by up-regulating expression of Bax, caspase-9,caspase-8, caspase-3 and down-regulating the expression of Bcl-2.
ABSTRACT
With the aim of a better characterization of the somatic recombination process in Trichoderma pseudokoningii, a progeny from crossings between T. pseudokoningii strains contrasting for auxotroph markers was characterized by RAPD markers and PFGE (electrophoretic karyotype). Cytological studies of the conidia, conidiogenesis and heterokaryotic colonies were also performed. The genotypes of the majority of the recombinant strains analyzed were similar to only one of the parental strains and the low frequency of polymorphic RAPD bands suggested that the nuclear fusions may not occur into the heterokaryon. In some heterokaryotic regions the existence of intensely staining hyphae might be related to cell death. We proposed that a mechanism of somatic recombination other than parasexuality might occur, being related to limited vegetative compatibility after postfusion events, as described for other Trichoderma species.