agar and afimoxifene

The hormone dependency of the MCF-7 breast cancer cell line, while extensively tested in liquid culture, has not been previously evaluated under conditions of anchorage-independent growth in serum-free media. Using the soft agar clonogenic assay, we demonstrate that physiologically relevant concentrations of estradiol (E2), progesterone (Pg), and prolactin (PRL) similarly stimulated MCF-7 cell colony formation in the absence of serum. Addition of an anti-insulin-like growth factor-I (IGF-I) antibody inhibited E2- and Pg-stimulated growth, while PRL action was not affected. Similar results were obtained with an anti-IGF-I receptor antibody, except that its inhibitory effect on Pg-induced colony formation was modest and not statistically significant. Administration of either an anti-transforming growth factor-alpha (TGF-alpha) antibody or an anti-epidermal growth factor (EGF) receptor antibody similarly inhibited E2-stimulated MCF-7 cell growth in soft agar, while neither antibody influenced Pg or PRL effects. Addition of TGF-beta 1, -beta 2, -beta 3 similarly suppressed MCF-7 cell colony formation in a dose dependent manner to a degree comparable to that observed with 4-OH-tamoxifen (4-OH-T). Furthermore, the growth inhibitory effect of 4-OH-T was completely reversed by an anti-TGF-beta antibody. We conclude that IGFs and TGF-alpha are important mediators of E2-stimulated MCF-7 cell growth in soft agar. IGFs may also be playing a role in Pg action, while neither growth factor is involved in PRL-stimulated colony formation. Finally, TGF-beta appears to be an important mediator of antiestrogen-induced inhibition of tumor growth.

Topics: Agar; Antibodies; Breast Neoplasms; Culture Media; Drug Interactions; Epidermal Growth Factor; Estradiol; Female; Growth Substances; Hormones; Humans; Insulin-Like Growth Factor I; Neoplasms, Hormone-Dependent; Progesterone; Prolactin; Tamoxifen; Transforming Growth Factor alpha; Transforming Growth Factor beta; Tumor Cells, Cultured; Tumor Stem Cell Assay

Methods and evaluation of the human tumor stem cell assay (HTSCA) are described. Advantages and disadvantages of the test system are elaborated. The in vitro/in vivo correlation in the drug screening of human ovarian carcinomas shows that the prediction of sensitivity to a cytotoxic agent is only possible in 64%. Prediction of drug resistance, however, seems to be possible in 95%. The number of patients that profit from the HTSCA seems to be only less than 10%. Our investigations describe the influence of various hormones and antiestrogens on the colony formation of human ovarian carcinoma cells. Tamoxifen and his major metabolite 4-hydroxy-tamoxifen were the most active agents. Both compounds inhibit the colony survival (70% at pharmacological concentrations) of 60% of the screened ovarian carcinomas. A significant correlation to the quantitative level of estrogen or progesterone receptors could not be proved. Colony formation of ovarian carcinoma cells was compared in the HTSCA as described by Hamburger and Salmon and in a methylcellulose-monolayer system. Our results show that the colony formation corresponds to the results of the original HTSCA: Cloning ovarian carcinoma cells in the methylcellulose-monolayer, however, seems to be technically easier and faster.

Topics: Agar; Antineoplastic Agents; Carcinoma; Cells, Cultured; Colony-Forming Units Assay; Drug Resistance; Estradiol; Female; Hormones; Humans; Medroxyprogesterone; Medroxyprogesterone Acetate; Methylcellulose; Ovarian Neoplasms; Progesterone; Prognosis; Tamoxifen; Tumor Stem Cell Assay

An antiestrogen affinity resin was synthesized by conjugating LY117018, a benzothiophene -derived antiestrogen, to epoxy-activated agarose. This affinity resin bound the Mr = 50 000 and 65 000 estrogen receptor proteins of rabbit uterine cytosol; in addition, it retained a protein from the cytosols of both rat and rabbit uteri that exhibited an ability to interact specifically with LY117018. The possibility that the LY117018 binding protein, which is distinct from estrogen receptors, may play a role in the antiestrogenic actions of LY117018 is discussed.

Topics: Agar; Animals; Carrier Proteins; Cytosol; Estrogen Antagonists; Female; Molecular Weight; Pyrrolidines; Rats; Receptors, Estrogen; Tamoxifen; Thiophenes; Uterus