Tandem application of flow cytometry and polymerase chain reaction for choice targets of minimal residual disease in childhood acute lymphoblastic leukemia / 中国当代儿科杂志

<p><b>OBJECTIVE</b>Minimal residual disease (MRD) is one of the most important prognostic factors in childhood acute lymphoblastic leukemia (ALL). Flow cytometry and PCR are two common techniques for examining MRD in ALL. This study aimed to identify MRD targets by tandem application of both techniques in children with ALL.</p><p><b>METHODS</b>From September 2001 to October 2003, 126 children with newly diagnosed ALL were enrolled on the treatment protocol ALL-XH-99. Tandem application of flow cytometry and PCR was performed to identify MRD targets in these patients.</p><p><b>RESULTS</b>1. Using sets of combined antibodies, immunophenotypic expression of leukemia cells was observed in 95 of 106 B-lineage ALL cases (89.6%). Only one aberrant immunophenotype was observed in 11 cases (11.6%) and most patients with B-lineage ALL (88.4%) expressed at least two suitable targets. 2. Using PCR technique, T-cell receptor (TCR) or immunoglobulin gene rearrangements were identified in 26 of 27 patients (96.3%). Two or more monoclonal/ bi-allelic gene rearrangements were identified in 17 cases (65.4%). The majority (70%) of T-lineage ALL cases contained TCRVgammaI-Jgamma1.3/2.3. Cross-lineage TCR rearrangements were found in 57.1% of cases with B-lineage ALL. 3. Suitable MRD targets of immunophenotypic abnormalities or antigen receptor gene rearrangements were detected in 121 patients (96.0%).</p><p><b>CONCLUSIONS</b>MRD targets were identified using tandem application of flow cytometry and PCR in almost of children with ALL. Cross-lineage TCR rearrangements and bi-allelic gene rearrangements were observed in many patients.</p>

Apoptosis mechanism in human chronic myelogenous leukemia K562 cells induced by tetra-arsenic tetra-sulfide / 中国实验血液学杂志

To explore the effects of tetra-arsenic tetra-sulfide (As(4)S(4)) in treatment of human chronic myelogenous leukemia K562 cells and its mechanism, trypan blue staining and microculture MTS assay were used to measure the effects of As(4)S(4) on growth inhibition of K562 cells; the morphologic change was determined by Wright's staining assay. The apoptosis rate and cell cycle were detected by flow cytometry; the changes of transcript and protein level were determined by real-time quantitative RT-PCR and Western blot analysis, respectively. The results indicated that As(4)S(4) had significant cytotoxicity on K562 cells. At the concentration of 0.5 micromol/L, the cell viability decreased significantly after being cultured with As(4)S(4) for 24 hours. When the concentration was lower than 0.1 micromol/L, As(4)S(4) had a little effect on K562 cells. The effect of As(4)S(4) on K562 was time- and concentration- dependent. After being cultured with As(4)S(4) at the concentration of 1.0 micromol/L for 24 to 48 hours, K562 cells displayed typical morphological changes of apoptosis. At a concentration greater than or equal to 1.0 micromol/L, As(4)S(4) could induce apoptosis significantly. After 12 hours of incubation with 1.0 micromol/L As(4)S(4), the apoptosis rate increased from (3.47 +/- 0.42)% to (6.16 +/- 0.98%). At the same time, the percentage of cells in G(1) phase decreased from (69.65 +/- 3.24)% to (50.53 +/- 2.86)%, whereas the percentage of cells in G(2)/M phase increased from (9.56 +/- 2.51)% to (12.91 +/- 2.13)%. The mRNA level of Bcl-X(L) and the protein level of pAkt were down-regulated after the inhibition of As(4)S(4), while the mRNA expression of Bcl-2, Bad and Bax had no change. Both of the transcript and protein level of bcr-abl had no change after incubation with As(4)S(4). It is concluded that As(4)S(4) can inhibit the growth of K562 cells efficiently through inducing apoptosis and cell cycle arrest. It seems that As(4)S(4) interferes with pAkt pathway and down-regulates Bcl-X(L), which may be involved in the response of K562 to this agent.

Preliminary study of VEGF and its receptor expression on childhood acute lymphoblastic leukemia and its relativity to clinical manifestations / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between differential expression of VEGF and its receptors and clinical characteristics of childhood acute lymphoblastic leukemia (ALL).</p><p><b>METHODS</b>Expressions of VEGF and its receptors (Flt-1, KDR) were assayed by ELISA and RT-PCR in healthy donors(20 cases), ALL patients in remission (20 cases), with low risk (29 cases) and with high risk (10 cases). The clinical data of all the patients and volunteers enrolled in this study were collected and analyzed according to the expression of VEGF and its receptors.</p><p><b>RESULTS</b>The expressions of VEGF were (574.37 +/- 208.45) ng/L, (387.93 +/- 175.86) ng/L, (135.80 +/- 111.28) ng/L and (91.16 +/- 41.34) ng/L in patients with high risk, standard risk, in remission and healthy donors, respectively. Expression levels of VEGF receptors were downwards with risk grades. The clinical manifestations were also in accord with the expression levels of VEGF and its receptors.</p><p><b>CONCLUSION</b>ALL patients with highly expressed VEGF and its receptors are usually with higher tumor burden, and refractory treatment. Detection of VEGF and its receptors might be one of prognostic marker for ALL treatment.</p>

Significance of TPMT activity and TGNs level detection for individualizing 6-mercaptopurine chemotherapy / 中华血液学杂志

<p><b>OBJECTIVE</b>To evaluate the activity and genotype of thiopurine methyltransferase (TPMT) and the concentration of thioguanine nucleotides (TGNs) as parameters for individualizing mercaptopurine (6-MP) therapy.</p><p><b>METHODS</b>Erythrocyte TPMT activity was measured by means of radiochemical assay. Sequence specific primer (SSP) PCR and restriction fragment length polymorphism (RFLP) were used to determine the mutations in TPMT genomic DNAs. Erythrocyte TGNs concentration in acute lymphoblastic leukemia (ALL) patients after 6-MP treatment was detected by high-performance liquid chromatography (HPLC).</p><p><b>RESULTS</b>The erythrocyte TPMT activity in Han population was 16.6 +/- 4.5U/ml pRBCs (man 16.8 +/- 5.0 U/ml pRBCs, woman 16.5 +/- 4.4 U/ml pRBCs), the activity in 8.1% of the samples was lower than 10 U/ml pRBCs. There was no difference for TPMT activity by gender, age, and between healthy donors and ALL patients. For TPMT genotypes, there were 5 cases of TPMT * 2, 4 TPMT * 3A, 6 TPMT * 3B, 10 TPMT * 3C and 5 unknown in 30 subjects who had low TPMT activity. In children with ALL, the TGNs level did show a negative correlation with TPMT activity at diagnosis and 7 approximately 14 days after 6-MP therapy and with WBC count 14 days after the determination of TGNs.</p><p><b>CONCLUSION</b>Detection of TPMT activity before 6-MP therapy and TGNs level during 6-MP therapy may be helpful for preventing side effects from antipurine metabolic drug overdose, and individualizing 6-MP chemotherapy in children with ALL.</p>