[Reversal of multidrug resistance of HL-60 adriamycin resistant leukemia cell line by quercetin and its mechanisms].

OBJECTIVE: Quercetin, a widely distributed natural flavonoid with a variety of biological functions, can reverse multidrug resistance (MDR) in leukemia according to recent researches. The aim of this study was to investigate the mechanisms of reversal of multi-drug resistance by quercetin mainly in respect of membrane transporters. METHODS: MTT cell viability assay was used to verify the chemo-sensitization to daunorubicin (DNR) by quercetin in HL-60/ADM cell line and determine the effective reversal concentration, the expression of MRP(1) gene and its protein product, multidrug resistant associated protein 1 by RT-PCR and flow cytometry By confocal laser scanning microscopy, the subcellular distribution of DNR in HL-60/S and HL-60/ADM cells was examined before and after quercetin exposure. RESULTS: Compared with HL-60/S, 20-40 micromol/L quercetin in vitro remarkably enhanced the sensitivity of HL-60/ADM cells to daunorubicin, down-regulated the expression of MRP(1) gene and its protein product MRP(1), restored the abnormal subcellular distribution of daunorubicin, so as to reverse MDR. Moreover, such an effective concentration of quercetin was non-toxic to the cells. CONCLUSION: Quercetin could be a candidate of effective multidrug resistance-reversing agent with low toxicity in leukemia chemotherapy.

[The relationship between cytochrome P450, subfamily IIIA, polypeptide 5 gene and drug resistance in leukemia cell lines].

OBJECTIVE: To investigate if the transcription, expression and activities of cytochrome P450, subfamily IIIA, polypeptide 5 gene (CYP3A5) are correlated with drug resistance in leukemia cell lines. METHODS: Using RT-PCR, immunohistochemistry and reverse-phase high-performance liquid chromatography (HPLC) assay, CYP3A5 mRNA protein and activities in leukemia cell lines were detected. Daunorubicin (DNR) sensitivity profiles of leukemia cell lines were obtained with MTT assay. Cell cycle characteristics and apoptosis induced by DNR were observed with flow cytometry (FCM) analysis. RESULTS: K562, U937, HL-60, NB4 and Jurkat cells were chosen as experimental cell line panels. It was found that CYP3A5 mRNA were measured only in K562 and U937 cells. CYP3A4 and CYP3A7 were not detectable in each cell line. The five leukemia cell lines presented sensitivity to DNR (IC(50), mg/L) in an order as follows: NB4 (0.068 +/- 0.036) > Jurkat (0.076 +/- 0.013) > HL-60 (0.092 +/- 0.016) > K562 (0.148 +/- 0.041) > U937 (0.150 +/- 0.035). Interestingly, K562 and U937 cells (cell lines with CYP3A5 gene transcription) were more resistant to DNR as compared with the other three cell lines in a statistically significant way (P < 0.01). Furthermore, expression and activities of CYP3A5 gene and cell cycle characteristics were observed in K562 and NB4 cells, which represented cell lines with or without CYP3A5 gene transcription respectively. In comparison with NB4 cells, K562 cells expressed CYP3A5 protein and showed a statistically significant higher CYP3A5 activity (3.075 +/- 0.036) x 10(-3) versus (1.635 +/- 0.196) x 10(-3), P < 0.05. FCM analysis showed that S phase cell proportions were similar in K562 and NB4 cells. Incubation with DNR (1 mg/L) for 6 hours induced a remarkable apoptosis peak in NB4 cells, while such peak not occur in K562 cells (apoptosis cell percentage 18.4% and 0.8% respectively). CONCLUSION: Only CYP3A5 gene of CYP3A subfamily were detectable in leukemia cell lines, and its transcription, expression and activities were correlated with drug resistance in leukemia cell lines.

[Dynamic observation of vascular endothelial growth factor (VEGF)/VEGF-receptors expression in acute leukemia].

OBJECTIVE: To investigate the expression of vascular endothelial growth factor (VEGF)/VEGF-receptors and its relation to bone marrow angiogenesis in acute leukemia patients before and after chemotherapy. METHODS: Bone marrow biopsies from 122 cases with different stages of human acute leukemia were immunostained with anti-vascular endothelial growth factor, anti-fms-like tyrosine kinase (Flt-1) and anti- kinase-domain insert containing receptor (KDR) antibodies with envision two-step immunohistochemical staining method. RESULTS: The expression of VEGF and KDR protein in remission patients was 5.3 (3.3 - 9.0) and 2.0 (1.0 - 4.0) being significantly lower than newly diagnosed untreated patients 6.0 (3.3 - 12.0) and 5.3 (3.3 - 8.0) (P < 0.05, 0.01). However nonsignificant decrease was shown among non-remission patients. In relapsed patients the expression of VEGF and KDR was significantly increased as compared with that in newly diagnosed patients. Flt-1 staining levels were in the same range between the newly diagnosed untreated patients and control group (P > 0.05), but significantly increased in remission or relapse patients, being 3.3 (1.7 - 5.3) in the remission group and 3.3 (2.0 - 5.3) in the relapse group (P < 0.01). Expression of VEGF and KDR protein was significantly higher in patients with a high degree of bone marrow microvessel counts as compared with those with a low degree and the expression correlated well with microvessel counts (P < 0.01). There was a positive correlation of the percentage of bone marrow blasts with VEGF and KDR expression in AML patients (r = 0.429, 0.359; P = 0.005, 0.02), and with VEGF expression in ALL patients (r = 0.522; P = 0.03). CONCLUSION: VEGF and its two specific cellular receptors are expressed in both haematopoietic cells and endothelial cells. VEGF may be a autocrine factor and modulates the angiogenic reaction in bone marrow as a paracrine factor. VEGF and its cellular receptor KDR may constitute promising targets for antiangiogenic and antileukemic treatment strategies.

[Preparation and identification of monoclonal antibody against PNAS-2 protein].

This study was purposed to prepare and primarily identify the specific monoclonal antibodies (McAbs) against the apoptosis related protein PNAS-2 so as to provide the essential tool for study of PNAS-2 function. The McAbs against PNAS-2 were prepared via the immunization of mice, cell fusion and cloning using synthetic peptide of PNAS-2 as immunogen; the specificity, titer and subtype of McAb were detected by Western blot, ELISA and immunofluorescence. The results showed that the stable hybridoma cell line S-31-7 producing McAbs against PNAS-2 protein was successfully obtained. The immunoglobulin of the McAb was identified to be IGg1lambda. The titer of ascetic fluid fled McAb were 1:8,000. A single specific band with 28 kD was shown in Western blot test, and the antigen recognized was present in cell cytoplasm by immunofluorescence. In conclusion, the obtained McAb against PNAS-2 displays strong specificity and high titer, which may be applied to the advanced research on PNAS-2 protein.

[Polymorphisms of CYP3A5 gene in acute leukemia patients and their role in chemotherapy and prognosis].

The objective of study was to investigate the role of the polymorphisms and protein expression of CYP3A5 gene in the therapy and prognosis of acute leukemia (AL) patients, the polymorphisms of CYP3A5 gene and the expression of protein CYP3A5 were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and immunohistochemistry method respectively. The results showed that there were three CYP3A5 genotypes in the 88 cases, namely CYP3A5*1/*1, CYP3A5*1/*3 and CYP3A5*3/*3 with frequencies of 26%, 50% and 24%, respectively. There were no significant differences in clinic data between the three groups, but the expressions of CYP3A5 of three groups were (36.6+/-19.2)%, (7.8+/-9.2)%, (0.5+/-0.9)%, the OS were (11.6+/-2.1) months, (30.5+/-12.2) months, (52.3+/-8.5) months, and the DFS were (7.5+/-1.8), (27+/-15.8), (52.3+/-8.1) months, respectively (p<0.05). It is concluded that the polymorphism of CYP3A5 gene is not related with the morbidity of AL, but closely associated with the expression of CYP3A5 in AL patients, and the latter are closely associated with the chemotherapeutic effect and prognosis. CYP3A5 genotype may be used as a new predictor to the chemotherapeutic effect and prognosis in AL cases.

[Expression spectra of apoptosis-related gene pnas-2].

To explore the expression spectra of apoptosis-related gene pnas-2 in normal tissues and acute leukemia (AL) patient tissues, the expressions of pnas-2 gene in tissues including heart, brain, placenta, lung, liver, skeletal muscle, kidney, pancreas, spleen, lymph node, thymus, leukocyte, bone marrow and fetal liver were detected by Northern blot. The expressions of pnas-2 in samples including 44 de novo, 9 non-CR, 27 CR and 12 relapsed AL patients were measured by real-time RT-PCR and Northern blot, and the expression levels of pnas-2 in normal and tumor tissues from 31 patients with malignancies were also detected. The results showed that pnas-2 was not expressed in the most tissues except in placenta. The results of real-time PCR indicated that pnas-2 expressions in samples of de novo, non-CR and relapsed patients ware significantly higher than that in CR, tumor tissues and normal tissues. In serial monitoring of 7 AL patients, the expression level of pnas-2 was high at first visit examination, but remarkably decreased after remission, and the pnas-2 expression level increased again when relapsed. It is concluded that the pnas-2 is specifically up-regulated in acute leukemia patients, which might be an oncogene and participate in leukemogenesis.

[Correlation between expression of apoptosis-related gene pnas-2 and leukemia].

The study was purposed to explore the correlation between apoptosis-related gene pnas-2 and leukemia. The RT-PCR was performed to detect the expression levels of pnas-2 gene in NB4, K562, U937 cells before and after treatment with AS(4)S(4), and to analysis the expression change of pnas-2 gene in bone marrow cells from patients with acute leukemia before and after chemotherapy. The results showed that the expression of pnas-2 gene in arsenic sulfide treated NB4 cells was down regulated in time-dependent manner, but the same outcome in K562 and U937 cells after being treated with AS(4)S(4) was not found. The positive expression rate of pnas-2 in cells from untreated patients with acute leukemia was 100%, and was significantly higher than that in normal control group. After chemotherapy, the expression was negative in complete remission patients, whereas in no-remission patients there were no significant differences of expression of pnas-2 before and after treatment. It is concluded that the pnas-2 gene may be closely related with apotosis of arsenic sulfide treated APL cells, and may consider as a molecular biological remission marker in acute leukemia.

[Effect of recombinant human granulocyte colony-stimulating factor on neutrophil morphology, function and phenotype in patients with acute leukemia undergoing chemotherapy].

This study was to explore the effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on neutrophil morphology, function and phenotype in patients with acute leukemia undergoing chemotherapy. Neutrophil morphology was observed under microscope with oil immersion; phagocytotic function was examined by measuring the amount of hydrogen peroxide produced by neutrophil; chemotaxis was analyzed by agarose method; oxidative burst was analyzed by flow cytometry using immunofluorescence technique; neutrophil phenotype was analyzed by flow cytometry and immunofluorescence techniques. The results showed that after rhG-CSF administration, the increased "toxic" granulation, vacuoles and Döhle bodies were observed in neutrophils of patients with acute leukemia. Compared with normal control, the functions of phagocytosis, chemotaxis, oxidative burst of neutrophil were impaired after chemotherapy, while these functions were enhanced and returned to normal level or even to be exceeded after administration of rhG-CSF. In patients with acute leukemia the neutrophil presented significantly higher expression of CD64 and CD62L than that in normal control, and a mild increase of CD64 expression and significant increase of CD62L expression were found in patients after rhG-CSF treatment. No modifications of CD16, CD32, CD14 and CD11b expression were detected in these patients before or after G-CSF administration. It is concluded that rhG-CSF administration can modify the morphology, function and phenotype of neutrophils in the patients with acute leukemia undergoing chemotherapy, and these modifications of neutrophil behavior may be supposed to be a reason for the enhancement of organism anti-infection ability.

[Effects of Red Orpiment on Cell Morphology and Expression of PML mRNA and Protein in NB4, and HL-60 Cells]

In this study the effects of red orpiment on NB4 and HL-60 cells were tried to determine. Semi-quantitative RT-PCR to determine the PML mRNA expression, immuno-fluorcscence study, together with the fluorescence stain and morphological observations were used. The results showed that: (1) red orpiment induces apoptosis morphologically in NB4 and HL-60 cells, the morphology of typical apoptosis can be seen in NB4 and HL-60 cells after 12 hours of treatment with red orpiment. Through the Wright's stain, we can see the extensive membrane blebbing, condensation of heterochromatin, and cell fragmentation, apoptotic body appearing. Many dead cells can be found on the second day. (2) in NB4 cells, red orpiment is shown to induce the PML-RARalpha chimera disappearance and to reorganize then to degradation of PML nuclear bodies which also seen in HL-60 cells, indirect immunofluorescence staining of PML with a specific monoclonal antibody was performed in control and treated cells. In NB4 cells, the control was diffusely microspeckled pattern of immunoreactivity. Upon red orpiment treatment, the microspeckled pattern disappeared, PML protein reversed into normal location. and the the size and the brightness of the particles were increased obviously. The normal nuclear distribution of PML protein was seen in untreated HL-60 cells. After treatment with red orpiment, in the nuclei of HL-60 cells, the size and the brightness of the particles were also increased. After two days of treatment with red orpiment, the immunofluorescent particles in cells almost disappeared. (3) the expression of PML mRNA is not changed in red orpiment-treated cells, RT-PCR to determine the PML mRNA expression in NB4 and HL-60 cells treated with red orpiment, the expression results are similar to the controls, that to say, the PML mRNA lever is unaffected. It was concluded that, red orpiment induced PML to play the effects of induce apoptosis in leukemia cells at the translational level and inhibited the proliferation of leukemia cells.

[Restorative effect of quercetin on subcellular distribution of daunorubicin in multidrug resistant leukemia cell lines K562/ADM and HL-60/ADM].

BACKGROUND & OBJECTIVE: Quercetin, a widely distributed natural flavonoid with a variety of biological functions, can reverse multidrug resistance (MDR) in leukemia according to recent researches. This study was to investigate the mechanism of quercetin restoring subcellular distribution of daunorubicin (DNR) in multidrug resistant leukemia cell lines, K562/ADM and HL-60/ADM, and reversing their MDR. METHODS: MTT cell viability assay was used to verify the sensitization of DNR by quercetin in K562/ADM and HL-60/ADM cells,and determine the reverse concentration extent,confocal laser scanning microscope was used to observe the subcellular distribution of DNR in K562/ADM and HL-60/ADM cells,and relevant sensitive cell lines, K562/S and HL-60/S,before and after quercetin exposion. RESULTS: Compared with K562/S and HL-60/S cells,20-40 micromol/L of quercetin in vitro remarkably enhanced the sensitivity of K562/ADM and HL-60/ADM cells to DNR, restore the subcellular distribution of DNR, so as to reverse MDR. CONCLUSION: quercetin could be a candidate of effective multidrug resistance-reversing agent in leukemia chemotherapy.

[Study of CYP3A5 in drug resistance mechanisms in acute leukemia].

OBJECTIVE: To investigate if CYP3A5 is involved in drug resistances mechanisms of acute leukemia. METHODS: By using RT-PCR, immunohistochemistry and MTT assay, CYP3A5 mRNA and protein were detected in leukemia cell lines and acute leukemia patients, meanwhile transcriptional regulation of CYP3A5 induced by daunorubicin was observed. A pcDNA3-CYP3A5 reconstituted plasmid and its stably transfected cell line HL-60/CYP3A5 were both established. RESULTS: CYP3A5 mRNA was detected in K562 and U937 cells, whose IC(50) values of daunorubicin were 2.1-fold higher than those of NB4 and HL-60 cells. Bone marrow CYP3A5 positive blast cell percentage at the time of diagnosis in primary drug resistance group (17.2%) was significantly higher than that of continuous complete remission (CCR) group (0.4%) and secondary drug resistance group (5.4%). In their first complete remission of the early relapsed group, the positive rate had been 23.9% as compared with that of CCR group (1.3%). Daunorubicin increased CYP3A5 mRNA level in K562/A02 and activated its transcription in HL-60/ADR. HL-60/CYP3A5 cell was significantly resistant to daunorubicin and vincristine than HL-60 cells did (3.0 and 4.0 times, respectively). CONCLUSION: CYP3A5 expressed in leukemia cells may cause in situ metabolization of many kinds of anticancer drugs, thus led to drug resistance.

[Effect of ATRA and DNR on the expression and secretion of VEGF in leukemic cells].

OBJECTIVE: To investigate the expression of VEGF mRNA and secretion of VEGF protein in NB4 and HL-60 cells affected by all-trans retinoic acid (ATRA) and daunorubincin (DNR) respectively. METHODS: Semi-quantitative RT-PCR and ELISA were used to study the expression of VEGF mRNA and secretion of VEGF protein in NB4 and HL-60 cell lines treated by ATRA and DNR respectively. RESULTS: VEGF was expressed in both NB4 and HL-60 cells. The expression of VEGF mRNA and secretion of VEGF protein could be down-regulated by ATRA and DNR respectively in a time and dose dependent manner. CONCLUSION: Besides inducing apoptosis and restraining proliferation of leukemic cells, ATRA and DNR exerted their anti-leukemia effects by reducing angiogenesis via reduction of angiogenic reaction stimulating signals.