ABSTRACT
The sensitivity of normal (MCF-7/WT) and doxorubicin-resistant (MCF-7/R) breast cancer cells to the antiproliferative effect of ethynylestradiol 11alpha-derivatives with the cytostatic residue in the 3-position of the steroid ring (antiestrogen cytostatics) was studied by evaluating cell viability using methylthiazole tetrazolium staining. The antiproliferative effects of these agents on cell lines in the presence of doxorubicin were compared. Antiestrogen cytostatics produced weaker cytostatic effect on MCF-7/WT cells, but more potent cytostatic effect on MCF-7/WT cells compared to those of doxorubicin. Moreover, administration of these agents in combination with doxorubicin more significantly suppressed proliferation of tumor cells. Accumulation and efflux of cytostatic doxorubicin in MCF-7/R cells were studied in the presence and absence of antiestrogen cytostatic Po716. Confocal laser microscopy showed that doxorubicin accumulation in MCF-7/R cells in the absence of Po716 took 20 min, while in the presence of antiestrogen cytostatic this process took 5 min. The rate of doxorubicin transport from tumor cells was much lower in the presence of the test antiestrogen cytostatic. Our results suggest that antiestrogen cytostatics increase the sensitivity of resistant MCF-7/R cells to doxorubicin by modulating the mechanisms of multidrug resistance of tumor cells.
Subject(s)
Antibiotics, Antineoplastic/administration & dosage , Breast Neoplasms/drug therapy , Doxorubicin/administration & dosage , Estradiol Congeners/administration & dosage , Estrogen Receptor Modulators/administration & dosage , Breast Neoplasms/pathology , Cell Line, Tumor , Cell Proliferation/drug effects , Drug Resistance, Neoplasm , Drug Synergism , Ethinyl Estradiol/administration & dosage , Ethinyl Estradiol/analogs & derivatives , Female , HumansABSTRACT
We studied the effect of four conjugated synthetic derivatives of estrone and ethynylestradiol and bis-beta-chloroethylamine-containing substance on activity of plasma membrane enzymes 5'-nucleotidase and N+-K+-ATPase. As differentiated from precursors, estrogen cytostatics decreased activity of plasma membrane enzymes. Reference preparations chlorophenacyl and estradiol had little effect on activity of 5'-nucleotidase and N+-K+-ATPase. These data suggest that damage to plasma membrane enzymes is related to the effect of estrogen cytostatic molecules. Test compounds produced an antiproliferative effect on estrogen-independent tumor cells, which strongly correlated with a decrease in activity of plasma membrane enzymes 5'-nucleotidase and N+-K+-ATPase. The derivative of ethynylestradiol with the cytostatic residue in the 3-position of the steroid nucleus (Po-714-11alpha) most significantly modulated enzyme activity.
Subject(s)
5'-Nucleotidase/drug effects , Antineoplastic Agents, Hormonal/toxicity , Cell Membrane/enzymology , Estrogens/toxicity , Sodium-Potassium-Exchanging ATPase/drug effects , Animals , Antineoplastic Agents, Hormonal/chemistry , Cell Division/drug effects , Estrone/chemistry , Estrone/toxicity , Ethinyl Estradiol/chemistry , Ethinyl Estradiol/toxicity , Ethylamines/chemistry , Ethylamines/toxicity , Female , Mammary Neoplasms, Experimental/drug therapy , Mice , Neoplasm Transplantation , Rats , Sarcoma/drug therapy , Skin Neoplasms/drug therapyABSTRACT
We studied binding of 10 new bis-beta-chloroethylamine derivatives of synthetic estrogens of different chemical structure to estradiol receptors in cytosolic fraction of breast carcinoma tissue and to blood plasma proteins. 11alpha-derivatives of estrone and ethynylestradiol with bis-beta-chloroethylamine radical at the 3-position were most potent, while 11beta-substances with the cytostatic residue in this position less effectively competed with labeled estradiol for estradiol receptors. Estrone derivatives with cytostatic residue at the 3-position bound primarily to serum albumin. Ethynylestradiol derivatives with cytostatic residue at the 3-position of the steroid nucleus bound to plasma globulins. Cytostatic radical at the 11-position changed spatial conformation of estrogen cytostatics and they lost their ability to interact with estradiol receptors and blood plasma proteins.
Subject(s)
Antineoplastic Agents, Hormonal/chemistry , Blood Proteins/metabolism , Breast Neoplasms/metabolism , Carcinoma/metabolism , Estradiol Congeners/chemistry , Estradiol Congeners/pharmacology , Animals , Antineoplastic Agents, Hormonal/pharmacology , Binding Sites , Binding, Competitive , Cytosol/metabolism , Dose-Response Relationship, Drug , Female , Humans , Molecular Structure , Rats , Receptors, Estradiol/metabolism , Reference Standards , Structure-Activity RelationshipABSTRACT
The effects of four new synthetic bis-beta-chloroethylamine-containing estrogens and known cytostatic agents chlorophenacyl and estradiol mustard were compared on monolayer cultures of transformed L-929 fibroblasts (from murine skin sarcoma). The drugs within the concentration range of 10(-5)-5 10(-7)M inhibited proliferation of cultured cells by 67%. Chlorophenacyl displayed the least antiproliferative activity (15% inhibition at 10(-5) M). Steroid nucleus introduced into the molecule enhanced antiproliferative activity of test drug in comparison with chlorophenacyl, probably due to accumulation of the hormone-cytostatic molecules in cells. Estradiol had no effect on proliferative activity of L-929 cells, and no specific estrogen-binding sites were found in cultured transformed fibroblasts. The antiproliferative effect of hormone-cytostatics on this culture is not mediated via specific interactions with estrogen receptors.