Regression of human breast tumor xenografts in response to (E)-2'-deoxy-2'-(fluoromethylene)cytidine, an inhibitor of ribonucleoside diphosphate reductase

• Published in: Cancer research (Chicago, Ill.) Vol. 54; no. 6; pp. 1485 - 1490
• Main Authors: BITONTI, A. J, DUMONT, J. A, BUSH, T. L, CASHMAN, E. A, CROSS-DOERSEN, D. E, WRIGHT, P. S, MATTHEWS, D. P, MCCARTHY, J. R, KAPLAN, D. A
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 15.03.1994
• Subjects: Animals; Antineoplastic agents; Biological and medical sciences; Breast Neoplasms - drug therapy; Breast Neoplasms - enzymology; Breast Neoplasms - pathology; Cell Death - drug effects; Cell Death - physiology; Cell Division - drug effects; Chemotherapy; Deoxycytidine - analogs & derivatives; Deoxycytidine - pharmacology; Estrogens; Female; Humans; Medical sciences; Mice; Mice, Nude; Neoplasm Metastasis; Neoplasm Transplantation; Neoplasms, Hormone-Dependent - drug therapy; Neoplasms, Hormone-Dependent - enzymology; Neoplasms, Hormone-Dependent - pathology; Pharmacology. Drug treatments; Ribonucleoside Diphosphate Reductase - antagonists & inhibitors; Transplantation, Heterologous; Tumor Cells, Cultured - drug effects; Antineoplastic agent; Animal model; Deoxyribonucleoside; Established cell line; Mammary gland; Ribonucleoside-diphosphate reductase; Pyrimidine nucleoside; Tumor cell; Human; Enzyme; Rodentia; Enzyme inhibitor; Malignant tumor; In vitro; Cytosine derivatives; Mammary gland diseases; In vivo; Vertebrata; Chemotherapy; Experimental disease; Mammalia; Treatment; Mouse; Animal; Oxidoreductases; Fluorine Organic compounds; Ethylenic compound
• ISSN: 0008-5472; 1538-7445

(E)-2'-Deoxy-2'-(fluoromethylene)cytidine (MDL 101,731) is a mechanism-based inhibitor of ribonucleoside diphosphate reductase (J. Stubbe, personal communication), an enzyme involved in DNA synthesis and therefore a potential target for cancer chemotherapy. In the present report, we show that MDL 101,731 inhibits the proliferation of several human breast cancer cell lines, including the estrogen-dependent cell line, MCF-7, and the estrogen-independent cell lines MDA-MB-231, MDA-MB-468, and MDA-MB-435 in vitro at nanomolar concentrations (50% inhibitory concentration, 15-26 nM). Administration of MDL 101,731 caused marked regression of tumors which formed after s.c. inoculation of all four of the cell lines in athymic (nude) mice. MDA-MB-231 tumors were found to be most sensitive to MDL 101,731 with a 90-100% cure rate at doses of MDL 101,731 between 2 and 20 mg/kg, given as once daily i.p. injections, 5 days/week for as little as 3 weeks. Almost complete cessation of MDA-MB-231 tumor growth was obtained with a dose of 0.5 mg/kg MDL 101,731 following the same dosing regimen. MDA-MB-468, MDA-MB-435, and MCF-7 tumors were not as sensitive as MDA-MB-231, but tumor regression of 50, 65, and 80%, respectively, was obtained after 5-6 weeks of treatment. The effects of MDL 101,731 on spontaneous metastasis of MDA-MB-435 cells from the mammary fat pad to the lung was also examined, and it was found that the number of lung metastases was significantly decreased if mice received MDL 101,731 while the primary tumors were growing and after primary tumors were surgically excised. Additionally, preliminary evidence raises the possibility that MDL 101,731 may induce apoptosis in MDA-MB-231 tumors. Our data suggest that the use of MDL 101,731 for the treatment of breast cancer and possibly other solid tumors should be pursued.