RESUMO
Expression of cell cycle-regulating genes was studied in human myeloid leukemia cell lines ML-1, ML-2 and ML-3 during induction of differentiation in vitro. Myelomonocytic differentiation was induced by phorbol ester (12-o-Tetradecanoyl-phorbol-13-acetate, TPA), tumor necrosis factor alpha (TNFalpha) or interferon gamma (INFgamma), or their combination. Differentiation (with the exception of TNFalpha alone) was accompanied by inhibition of DNA synthesis and cell cycle arrest. Inhibition of proliferation was associated with a decrease in the expression of cdc25A and cdc25B, cdk6 and Ki-67 genes, and with increased p21(Waf1/Cip1) gene expression, as measured by comparative RT-PCR. Expression of the following genes was not changed after induction of differentiation: cyclin A1, cyclin D3, cyclin E1 and p27(Kip1). Surprisingly, cyclin D1 expression was upregulated after induction by TPA, TNFalpha with IFNgamma or BA. Cyclin D2 was upregulated only after induction by BA. The results of the expression of the tested genes obtained by comparative RT-PCR were confirmed by quantitative real-time (RQ) RT-PCR and Western blotting. Quantitative RT-PCR showed as much as a 288-fold increase of cyclin D1 specific mRNA after a 24h induction by TPA. The upregulation of cyclin D1 in differentiating cells seems to be compensated by the upregulation of p21(Waf1/Cip1). These results, besides others, point to a strong correlation between the expression of cyclin D1 and p21(Waf1/Cip1) on the one hand and differentiation on the other hand in human myeloid leukemic cells and reflect a rather complicated network regulating proliferation and differentiation of leukemic cells.
Assuntos
Ciclina D1/metabolismo , Ciclinas/metabolismo , Leucemia Mieloide/metabolismo , Leucemia Mieloide/patologia , Doença Aguda , Antineoplásicos/farmacologia , Western Blotting , Carcinógenos/farmacologia , Ciclo Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Ciclina D1/genética , Inibidor de Quinase Dependente de Ciclina p21 , Ciclinas/genética , Primers do DNA/química , Humanos , Interferon gama/farmacologia , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/farmacologia , Regulação para CimaRESUMO
Monoclonal antibody 2E12 was prepared by immunization of mice with fresh cells of chronic myeloid leukemia cell line MOLM-7. A panel of 15 leukemic cell lines (myeloid, promyelocytic, erythroid, B and T lymphoid) and numerous cultured patient's leukemia and myeloma cells were tested for reactivity with 2E12 antibody. A subset of cells in all cell lines and various number of patient's cells cultivated for 10 days or more were 2E12 positive. KG-1 and HL-60 cell lines were treated by camptothecin (CAM) (5 microg/ml, 4 h), washed and further cultivated without CAM. After 24 and 48 h in culture a considerable increase of 2E12 positivity was detected both in KG-1 and HL-60 cells, which well correlated with the increase of APO2.7 positivity and the sub-G1 peaks. The 2E12 positive cells were morphologically the same as cells in PCD, possibly apoptosis. We suggest that the 2E12 antibody detects a strong antigen on apoptotic cells which could be a part of the signaling process for ingestion by phagocytes.
