1.[Cytotoxic activity of dammarane triterpenoids from birch leaves].
Prokof'eva NG1, Anisimov MM, Kiseleva MI, Rebachuk NM, Pokhilo ND. Izv Akad Nauk Ser Biol. 2002 Nov-Dec;(6):645-9.
Cytotoxic activity of dammarane triterpenoids isolated from beach leaves was studied. These substances differ from the native ginseng genin (20(S)-protopanaxadiol) by the number, location, or configuration of OH-groups. Using fertilized egg cells of sea urchin Stronglyocentrotus intermedius we demonstrate that the orientation of C-3 OH-group has no effect on cytotoxic activity of triterpenoids as well as a higher activity of a triterpenoid with 3 alpha,12 beta-OH as compared to a C-3 ketone but lower activity as compared to a triterpenoid with 3 alpha,17 alpha-OH. Depending on the number of OH-groups the cytotoxic activity of triterpenoids decreases in the row: tetraol > pentaol > triol. Dammar-24-ene-3 alpha 2 beta,17 alpha,20(S)-tetraol (compound IV) is cytotoxic for the Ehrlich ascite carcinoma cells and this effect is additive to cytotoxic activity of anthracycline antibiotic carminomycin in vitro. Compound IV changes the permeability and microviscosity of the tumor cell membranes.
2.[Anthracycline antibiotics and their derivatives--inhibitors of topoisomerase I].
Dezhenkova LG, Teviashova AN, Olsuf'eva EN, Treshchalin ID, Shtil' AA, Preobrazhenskaia MN. Bioorg Khim. 2008 May-Jun;34(3):430-2.
The relationship between the structure of new semisynthetic derivatives of doxorubicin, daunorubicin, and carminomycin and their ability to inhibit topoisomerase 1 were studied. The new derivatives inhibit the activity of topoisomerase 1 at low concentrations, induce the death of K-562 leukemia cells in culture, and produce an antitumor effect in experimental animals with P388 leukemia.
3.Altered expression of topoisomerase IIalpha contributes to cross-resistant to etoposide K562/MX2 cell line by aberrant methylation.
Asano T1, Nakamura K, Fujii H, Horichi N, Ohmori T, Hasegawa K, Isoe T, Adachi M, Otake N, Fukunaga Y. Br J Cancer. 2005 Apr 25;92(8):1486-92.
KRN 8602 (MX2) is a novel morpholino anthracycline derivative having the chemical structure 3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin hydrochloride. To investigate the mechanisms of resistance to MX2, we established an MX2-resistant phenotype (K562/MX2) of the human myelogeneous leukaemia cell line (K562/P), by continuously exposing a suspension culture to increasing concentrations of MX2. K562/MX2 cells were more resistant to MX2 than the parent cells, and also showed cross-resistance to etoposide and doxorubicin. Topoisomerase (Topo) IIalpha protein levels in K562/MX2 cells were lower of those in K562/P cells on immunoblot analysis and decreased expression of Topo IIalpha mRNA was seen in K562/MX2 cells. Topoisomerase II catalytic activity was also reduced in the nuclear extracts from K562/MX2 cells when compared with K562/P cells. Aberrant methylated CpG of Topo IIalpha gene was observed in K562/MX2 cells when compared with the parent line on methylation-specific restriction enzyme analysis.