Altered centrosomes in ataxia-telangiectasia cells and rapamycin-treated Chinese hamster cells.
Rapamycin induces chromosome malsegregation in mammalian cell lines and yeast. Previous studies indicate that the function impaired in ataxia-telangiectasia (A-T) patients is necessary for both the growth inhibition and the chromosome malsegregation induced by rapamycin, and that treating the non-tumorigenic Chinese hamster cell line CHEF/18 with rapamycin results in supernumerary centrosomes and multipolar spindles. In this paper we report that lymphoblastoid cell lines established from A-T patients as well as hamster A-T-like cells are more resistant to rapamycin than the respective normal cell lines. Two cell lines derived from Nijmegen Breakage Syndrome (NBS) patients, who have clinical symptoms similar to those of A-T but a different molecular defect, were not resistant to rapamycin. Both A-T lymphoblastoid cells and A-T-like fibroblasts had giant centrosomes formed by more than two areas of gamma-tubulin-reacting material. Such giant centrosomes were also observed in CHEF/18 cells after prolonged treatment with rapamycin. Formation of giant centrosomes, possibly due to the coalescence of supernumerary centrosomes, was associated with increased aneuploidy in treated cells. Expression analysis of cell-cycle regulatory genes in rapamycin-treated human lymphoblastoid cells indicated that rapamycin decreased the expression of the tumor suppressor gene GADD45. The levels of RB, p21 and p53 mRNA were also decreased, although to a lesser extent. As rapamycin is often used as an immunosuppressant in pediatric transplant patients, these data indicate that caution should be taken, especially when the drug is given for prolonged periods of time.
Bonatti
Stefania
S
CNR Institute of Clinical Physiology, Pisa, Italy.
Simili
Marcella
M
Benedetti
Pier Alberto
PA
Morandi
Fabio
F
Menichini
Paola
P
Del Carratore
Renata
R
Barale
Roberto
R
Abbondandolo
Angelo
A
D000818:Animals; D001260:Ataxia Telangiectasia / Q000235:genetics* / Q000473:pathology; D002453:Cell Cycle; D002460:Cell Line; D018385:Centrosome / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure*; D002869:Chromosome Aberrations / Q000139:chemically induced*; D002875:Chromosomes / Q000648:ultrastructure; D006224:Cricetinae; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism; D008677:Metaphase; D015162:Micronucleus Tests; D018613:Microscopy, Confocal; D015233:Models, Statistical; D049932:Nijmegen Breakage Syndrome / Q000235:genetics*; D010641:Phenotype; D016160:Retinoblastoma Protein / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology*; D008941:Spindle Apparatus / Q000187:drug effects; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D000097642:GADD45 Proteins
D050759:Cyclin-Dependent Kinase Inhibitor p21; D047908:Intracellular Signaling Peptides and Proteins; D016160:Retinoblastoma Protein; D020123:Sirolimus; D016159:Tumor Suppressor Protein p53; D000097642:GADD45 Proteins