[Expression of NOV and BNIP3 gene in mouse myelomonocytic leukemia and its significance].

This study was aimed to investigate the expression level of NOV and BNIP3 mRNA in mice myelomonocytic leukemia (AML-M(4)) and its significance. The mice were inoculated intravenously with myelomonocytic leukemia cells of WEHI-3, and divided randomly into chemotherapy group and control (untreated) group. Bone marrow samples were then collected from both groups at different times. The NOV and BNIP3 mRNA expression were detected by TaqMan quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), and the relationship between these expression levels and clinical significance in leukemia incidence and progression were analyzed with ß-actin as the housekeeping gene. The results showed that the mean values of NOV and BNIP3 increased gradually from 2 weeks after inoculation and achieved highest level at death in control group. Expression level of NOV increased from 1.85E-05 before inoculation to 3.57E-02 at death (p < 0.05), and BNIP3 from 3.44E-03 to 3.48E-02. While 2 gene expression in the chemotherapy group decreased quickly to 2.51E-05 and 1.58E-03 (p < 0.05) respectively after chemotherapy, which were close to the level before inoculation (p > 0.05). The 2 gene expressions again rose at relapse, and difference of expression level between 2 group at death were no statistically significant (p > 0.05). It is concluded that the expression of NOV and BNIP3 in leukemia AML-M(4) is significantly higher than that in normal controls, of which high level expression is an important factor in the development of leukemia. Close relation between the therapeutic effect and expression level of these two genes suggests the great value in prognostic evaluation and MRD detection.

Role of prosurvival molecules in the action of lidamycin toward human tumor cells.

OBJECTIVE: Lidamycin, an enediyne antibiotic, leads to apoptosis and mitotic cell death of human tumor cells at high and low concentrations. The reason why tumor cells have distinct responses to lidamycin remains elusive. This study was to elucidate if cellular prosurvival molecules are involved in these responses. METHODS: Cleavage of chromatin and DNA was observed by chromatin condensation and agarose gel electrophoresis. Accumulation of rhodamine 123 in lidamycin-treated cells was assayed by flow cytometry. Cell multinucleation was detected by staining with Hoechst 33342. Western blot and senescence-associated beta-galactosidase (SA-beta-gal) staining were used to analyze protein expression and senescence-like phenotype, respectively. RESULTS: SIRT1 deacetylase remained unchanged in 0.5 nmol/L lidamycin whereas cleavage occurred when apoptosis was induced by lidamycin. Increased FOXO3a, SOD-1 and SOD-2 expression and transient phosphorylation of ERK were detected after exposure of human hepatoma BEL-7402 cells to 0.5 nmol/L lidamycin. High expressions of SIRT1 and Akt were found in colon carcinoma HCT116 p53 knock-out cells exposed to lidamycin. Degradation of PARP and p53 by lidamycin as a substitute for SIRT1 and Akt was confirmed with caspase inhibitor Q-VD-OPh and proteasome inhibitor MG132. Resistance to lidamycin-induced DNA cleavage was observed in breast cancer doxorubicin-resistant MCF-7 cells. This was not induced by P-glycoprotein as no accumulation of rhodamine 123 was detected in the resistant cells following exposure to lidamycin. In contrast to sensitive MCF-7 cells, a lower multinucleation rate for the resistant cells was measured following exposure to equal concentrations of lidamycin. CONCLUSIONS: Cellular prosurvival molecules, such as SIRT1, Akt, SOD-1, SOD-2 and other unknown factors can influence the action of lidamycin on human tumor cells.