Enhancement of radiation response by roscovitine in human breast carcinoma in vitro and in vivo.
Frequent deregulation of cyclin-dependent kinase (CDK) activation associated with loss of cell cycle control was found in most of human cancers. A recent development of a new class of antineoplasic agents targeting the cell cycle emerged as a small molecule CDK inhibitor, roscovitine, which presents potential antiproliferative and antitumoral effects in human tumors. Additional studies reported that roscovitine combined with cytotoxic agents can cooperate with DNA damage to activate p53 protein. However, little is known about the biological effect of roscovitine combined with ionizing radiation (IR) in human carcinoma, and no studies were reported thus far in p53 mutated carcinoma. In the breast cancer cell line MDA-MB 231, which lacks a functional p53 protein, we found a strong radiosensitization effect of roscovitine in vitro by clonogenic survival assay and in vivo in MDA-MB 231 xenograft model. Using Pulse Field Gel Electrophoresis, a strong impairment in DNA-double-strand break rejoining was observed after roscovitine and IR treatment as compared with IR alone. Cell cycle analysis showed a G(2) delay and no increase in radiation-induced apoptosis in the cells treated with IR or roscovitine and IR. On the other hand, we found a significant induction in micronuclei frequency after roscovitine and IR treatment as compared with IR alone. This effect was also observed in BALB murine cells in contrast to SCID murine cells, which are deficient in DNA-PKcs, suggesting a possible DNA-double-strand break repair defect in the nonhomologous end joining pathways. In MDA-MB 231 cells, the radiosensitization effect of roscovitine was associated with an inhibition of the DNA-dependent protein kinase activity caused by a marked decrease in Ku-DNA binding by using the electrophoretic mobility shift assay. In conclusion, we found a novel effect on DNA repair of the CDK inhibitor roscovitine, which acts as a radiosensitizer in vitro and in vivo in breast cancer cells lacking a functional p53.
Laboratoire Radiosensibilité des Tumeurs et des Tissus Sains UPRES EA 27-10, 94805 Villejuif, Cedex, France.
Laurence
L
Maggiorella
Eric
E
Deutsch
Valérie
V
Frascogna
Nicole
N
Chavaudra
Laurence
L
Jeanson
Fabien
F
Milliat
François
F
Eschwege
Jean
J
Bourhis
D000818:Animals; D034961:Antigens, Nuclear / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy*; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D003131:Combined Modality Therapy; D004265:DNA Helicases; D004260:DNA Repair / Q000187:drug effects; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D000072200:Ku Autoantigen; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D016513:Mice, SCID; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011687:Purines / Q000494:pharmacology*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D000077546:Roscovitine; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
D034961:Antigens, Nuclear; D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011687:Purines; D011838:Radiation-Sensitizing Agents; D000077546:Roscovitine; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen