p53-independent apoptosis and p53-dependent block of DNA rereplication following mitotic spindle inhibition in human cells.
We have studied the response of human transformed cells to mitotic spindle inhibition. Two paired cell lines, K562 and its parvovirus-resistant KS derivative clone, respectively nonexpressing and expressing p53, were continuously exposed to nocodazole. Apoptotic cells were observed in both lines, indicating that mitotic spindle impairment induced p53-independent apoptosis. After a transient mitotic delay, both cell lines exited mitosis, as revealed by flow-cytometric determination of MPM2 antigen and cyclin B1 expression, coupled to cytogenetic analysis of sister centromere separation. Both cell lines exited mitosis without chromatid segregation. K562 p53-deficient cells further resumed DNA synthesis, giving rise to cells with a DNA content above 4C, and reentered a polyploid cycle. In contrast, KS cells underwent a subsequent G1 arrest in the tetraploid state. Thus, G1 arrest in tetraploid cells requires p53 function in the rereplication checkpoint which prevents the G1/S transition following aberrant mitosis; in contrast, p53 expression is dispensable for triggering the apoptotic response in the absence of mitotic spindle.
Centro di Genetica Evoluzionistica CNR, c/o University "La Sapienza, ", Via degli Apuli, 4, Rome, 00185, Italy.
M
M
Casenghi
R
R
Mangiacasale
M
M
Tuynder
P
P
Caillet-Fauquet
A
A
Elhajouji
P
P
Lavia
S
S
Mousset
M
M
Kirsch-Volders
E
E
Cundari
D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins; D002503:Centromere / Q000187:drug effects / Q000378:metabolism; D020090:Chromosome Segregation / Q000187:drug effects; D019926:Cyclin B / Q000032:analysis; D056744:Cyclin B1; D004247:DNA / Q000096:biosynthesis; D053938:DNA Fragmentation / Q000187:drug effects; D004261:DNA Replication / Q000187:drug effects / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D016158:Genes, p53; D006801:Humans; D016547:Kinesins; D008940:Mitotic Index / Q000187:drug effects; D015739:Nocodazole / Q000494:pharmacology; D010750:Phosphoproteins / Q000032:analysis; D011123:Polyploidy; D008941:Spindle Apparatus / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000502:physiology
C534699:CCNB1 protein, human; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D010750:Phosphoproteins; D016159:Tumor Suppressor Protein p53; D004247:DNA; C438388:KIF20B protein, human; D016547:Kinesins; D015739:Nocodazole