Ki-67 as a marker for cell cycle regulation by interferon.
The effects of interferon (IFN) on the expression of the nuclear antigen Ki-67 were studied in the two IFN-sensitive tumour cell lines Daudi and 251 MG, known to be arrested in the cell cycle in separate stages. The GO/G1-arrested Burkitt's lymphoma cell line Daudi displayed an increasing fraction of Ki-67 negative cells with time, concomitant with an increasing proportion of growth arrested cells. A small fraction of Ki-67 positive cells were found mainly arrested in G2/M. In contrast, no effect on Ki-67 expression was seen in IFN-resistant Namalwa cells, nor in the sensitive glioma cell line 251 MG, which is blocked in the S phase of the cell cycle. Agents blocking the cells in other phases of the cycle did not affect Ki-67 expression. However, after serum deprivation, no Ki-67 expression was found in the glioma cell line, while restimulation initiated expression after 12 hours as cells entered the S phase. We conclude that the Ki-67 antigen was not down regulated in all cells inhibited by IFN and thus does not seem to be useful to monitor clinical effects of IFN treatment.
Lundblad
D
D
Institute of Applied Cell and Molecular Biology, University of Umeå, Sweden.
Landberg
G
G
Roos
G
G
Lundgren
E
E
D014408:Biomarkers, Tumor / Q000032:analysis* / Q000378:metabolism; D002051:Burkitt Lymphoma / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D002453:Cell Cycle / Q000187:drug effects*; D015536:Down-Regulation; D016193:G1 Phase; D016195:G2 Phase; D005910:Glioma / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D006801:Humans; D007372:Interferons / Q000494:pharmacology*; D019394:Ki-67 Antigen; D008942:Mitoxantrone / Q000494:pharmacology; D009687:Nuclear Proteins / Q000032:analysis* / Q000378:metabolism; D016192:Resting Phase, Cell Cycle; D014407:Tumor Cells, Cultured
D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D007372:Interferons; D008942:Mitoxantrone