Association of polymorphisms of cytosine arabinoside-metabolizing enzyme gene with therapeutic efficacy for acute myeloid leukemia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The cytosine arabinoside (Ara-C)-based chemotherapy is the major remedial measure for acute myeloid leukemia (AML). Deoxycytidine kinase (DCK) and cytidine deaminase (CDA) are the key enzymes in the metabolism of Ara-C. Many single nucleotide polymorphisms (SNPs) and haplotypes of DCK and CDA, which contribute to susceptibility to Ara-C, have been identified in Africans and Europeans. However, there has been no report about the relation among three SNPs in DCK (rs115543896, rs72552079, and rs111454937) and two SNPs in CDA (rs2072671 and rs60369023), and their clinical response to Ara-C for a Chinese population. In this study, we aimed to investigate whether these five SNPs are associated with the therapeutic outcomes of Ara-C-based chemotherapy regimens in patients with AML.</p><p><b>METHODS</b>A total of 151 Chinese patients with AML were enrolled in our study. SNPs genotyping were performed using the MassARRAY system by means of the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) method.</p><p><b>RESULTS</b>The results illustrated that DCKrs111454937 AA genotype was more frequent in patients with higher platelet count, and A allele frequency was significantly higher in the group £40 years, lower white blood cell (WBC) count patients group and the group with platelet counts > 60'10(9)/L. Meanwhile, both DCKrs72552079 TC (OR = 1.225, 95%CI = 1.225 - 9.851, P = 0.0192) and CDArs60369023 GA (OR = 9.851, 95%CI = 1.31 - 77.93, P = 0.0263) significantly improved Ara-C-based chemotherapy response. While DCKrs11554389 AA (OR = 0.147, 95%CI = 0.027 - 0.801, P = 0.0267) was associated with the decrease of Ara-C-based chemotherapy response.</p><p><b>CONCLUSION</b>It is evident that the DCK and CDA polymorphisms might be the important markers for the AML patients' therapy outcomes in a Chinese population.</p>

Relationship between single nucleotide polymorphisms in the deoxycytidine kinase gene and chemosensitivity of gemcitabine in six pancreatic cancer cell lines / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Single nucleotide polymorphisms (SNPs) in the deoxycytidine kinase (dCK) gene are associated with chemosensitivity to nucleoside analogs. 2',2'-Difluoro 2'-deoxycytidine (gemcitabine) is a first-line nucleoside analog drug in the treatment of pancreatic cancer. However, the association between SNPs in the dCK gene and chemosensitivity to gemcitabine has not been fully established. Therefore, the present study aimed to investigate the relationship between SNPs in the dCK gene and chemosensitivity to gemcitabine in human pancreatic cancer cell lines.</p><p><b>METHODS</b>Seven SNPs in the dCK gene were sequenced in six human pancreatic cancer cell lines. The chemosensitivity of these six cell lines to gemcitabine were evaluated in vitro with a Cell Counting Kit-8 (CCK-8) test. Inhibition rates were used to express the chemosensitivity of pancreatic cancer cell lines to gemcitabine.</p><p><b>RESULTS</b>The genotype of the A9846G SNP in the dCK gene was determined in six human pancreatic cancer cell lines. The cell lines BxPC-3 and T3M4 carried the A9846G SNP genotype AG, whereas cell lines AsPC-1, Mia PaCa2, SW1990 and SU86.86 carried the GG genotype. Cell lines with the AG genotype (BxPC-3 and T3M4) were more sensitive to gemcitabine compared with cell lines with the GG genotype (AsPC-1, Mia PaCa2, SW1990 and SU86.86) and significantly different inhibition rates were observed between cell lines carrying the AG and GG genotypes (P < 0.01).</p><p><b>CONCLUSIONS</b>Variants in the A9846G SNP of the dCK gene were associated with sensitivity to gemcitabine in pancreatic cancer cell lines. The dCK A9846G SNP may act as a genetic marker to predict chemotherapy efficacy of gemcitabine in pancreatic cancer.</p>

Correlation of deoxycytidine kinase gene expression with fludarabine resistance in patients with chronic lymphocytic leukemia / 中国实验血液学杂志

The study was purposed to explore the relationship between the expression of deoxycytidine kinase (dCK) gene and fludarabine (Flud) resistance in patients with chronic lymphocytic leukemia (CLL). The real time quantitative polymerase chain reaction (RQ-PCR) technique was used to detect the mRNA expression of dCK gene in the bone marrow or peripheral blood mononuclear cells from 30 CLL patients, the difference of dCK expression levels between CLL patients sensitive to Flud and patients resistant to Flud was analyzed. The results showed that dCK expression level in the Flud-sensitive patients was much higher than that in the Flud-resistant ones (p = 0.001); dCK expression level had no relationship with sex, age, Binet stage, IgVH mutations, CD38, ZAP-70 or p53 gene mutation (p > 0.05). It is concluded that low expression or deficiency of dCK in patients may contribute to resistance against Flud- and the prognostic significance of dCK expression remains to be further studied.

Expression of Gemcitabine-resistance-related gene and polymorphism of ribonucleotide reductase M1 gene promoter in Gemcitabine-resistant A549/Gem and NCI-H460/Gem cell lines / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To assay the expression of cytidine deaminase (CDA), ribonucleotide reductase subunit 1 (RRM1), phosphatase and tensin homologue deleted from chromosome 10 (PTEN), excision repair cross-complementation group 1 (ERCC1), deoxycytidine kinase (dCK) and RRM1(-)37A/C polymorphism, which have been shown relevant to gemcitabine resistance in two human gemcitabine-resistant non-small cell lung cancer cell lines A549/Gem and NCI-H460/Gem, so as to make clear how do they vary during the course of acquiring resistance to gemcitabine.</p><p><b>METHODS</b>The human gemcitabine-resistant non-small cell lung cancer cell lines A549/Gem and NCI-H460/Gem were established in our Department by repeated clinical serum peak concentration and gradually increasing doses. Real-time fluorescent quantitative PCR was used to examine the expression of CDA, RRM1, PTEN, ERCC1, dCK and RRM1(-)37A/C polymorphism in those cell lines at different time points during their induction process.</p><p><b>RESULTS</b>The resistance indexes of A549/Gem and NCI-H460/Gem cells reached 163.228 and 181.684, and then remained stable at 115.297 and 129.783, respectively. The expression of CDA, RRM1, PTEN and ERCC1 varied along with the changing gemcitabine resistance indexes, but expression of dCK did not change apparently. The wild type promoter was able to amplify the genomic DNA in different induction stages of A549/Gem and NCI-H460/Gem cells, but allelotype did not, indicating that the gene type of A549/Gem, NCI-H460/Gem and their parental cells remaining still wild type.</p><p><b>CONCLUSION</b>Compared with their parental cells, the expressions of CDA, RRM1, PTEN and ERCC1 in human gemcitabine-resistant non-small cell lung cancer cell lines A549/Gem and NCI-H460/Gem rise, the expression of dCK changes inapparently, therefore, their gene type are remaining wild type.</p>

Effect of genetic alterations of cytarabine-metabolizing enzymes in childhood acute lymphoblastic leukemia

Single nucleotide polymorphisms [SNPs] of deoxyctidine kinase [dCK] and cytidine deaminase [CDA] are known to alter their enzymatic activities, which affect the metabolism of cytarabine. Currently, treatment of childhood acute lymphoblastic leukemia [ALL] includes cytarabine, especially in high-risk patients. Therefore we hypothesized that a genetic variation of dCK and CDA genes may influence the risk of cytarabine-related toxicities and early response to treatment. We included children diagnosed with ALL and lymphoblastic lymphoma [LL] stage III and IV. The patients received a modified ST Jude Total Therapy Study XV protocol. Cytarabine was used during induction remission [low-dose cytarabine] and reinduction II [high-dose cytarabine] phases. Genotyping of dCK -360 > G and -201 > T and CDA 79A > C and 208G > A was performed. Minimal residual disease [MRD] at the end of the induction phase was measured using flow cytomery. Ninety-four children with ALL [n=90] and LL [n=4] were analyzed. The median age at diagnosis was 5.8 years [range, 0.4-15 years]. All four SNPs showed predominant wild type alleles. There was no CDA-208A allele in our population. Children with dCK-360G allele were at risk of mycositis after receiving low-dose cytarabine [OR=3.7; 95% CI, 1.2-11.3]. Neither dCK nor CDA polymorphisms affected the MRD status at the end of induction phase. The dCK-360G allele was found to found to increase the risk of mucositis after expose to low-dose cytarabine in childhood ALL therapy

Relationship between the expression of the genes encoding the key enzymes for cytarabine metabolism and the pharmacokinetics of cytarabine in the treatment of childhood acute leukemia with high-dose cytarabine / 中华儿科杂志

<p><b>OBJECTIVE</b>It has been reported that high-dose cytarabine (HD-AraC) was very effective for childhood hematological malignancies, especially for improving the long-term survival of high-risk acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and T-cell lymphoid malignancies (T-ALL, T-cell non-Hodgkin's lymphoma). This study aimed to evaluate the pharmacokinetics of HD-AraC for childhood hematological malignancies, and the relationship between the expression of the genes coding the key enzymes for Ara-C metabolism with the outcome of the patients.</p><p><b>METHODS</b>The drug levels of Ara-C in plasma and cerebrospinal fluid were detected with HPLC while HD-AraC was used, the expression of deoxycytidine kinase (dCK) and cytidine deaminase (CDA) mRNA in human leukemia cell lines and the bone marrow cells were investigated in 48 cases of childhood hematological malignancies with RT-PCR methods, and the relationship between the expression of these enzymes mRNA and the outcome of the patients was analyzed.</p><p><b>RESULTS</b>(1) When HD-AraC was used, the plasma levels of Ara-C and Ara-U could be respectively about 50 times and 25 times higher than those obtained when the patients were treated with regular dose of Ara-C treatment, and the level of Ara-C in cerebrospinal fluid could reach about 10% of plasma level of Ara-C. (2) There were significantly different expressions of dCK mRNA in different childhood acute leukemia (AL) patients, which were markedly related to the chemotherapy results. The expression of dCK in ALL was much higher than that in AML and relapsed AL cases. There were no significant differences in expressions of dCK in T-ALL and B lineage ALL. (3) In vitro study found that the expressions of dCK and CDA mRNA did not change in leukemia cell lines incubated at different doses and times of Ara-C.</p><p><b>CONCLUSIONS</b>HD-AraC was a very effective protocol for childhood hematological malignancies for it could significantly elevate the plasma and cerebrospinal fluid drug levels. The expression of dCK may be an important factor in predicting the long-term outcomes of children with hematological malignancies. Good long-term outcomes of the childhood T-ALL could be achieved as the B lineage ALL had been treated with HD-AraC regimen. As the expression levels of dCK were much lower, it may be necessary for the treatment of AML with HD-AraC for consecutive three days.</p>

Cytosine arabinoside-metabolizing enzyme genes are underexpressed in children with MLL gene-rearranged acute lymphoblastic leukemia

Infant acute lymphoblastic leukemia (IALL) is characterized by mixed lineage leukemia (MLL) gene rearrangements, unique gene expression profiles, poor prognosis, and drug resistance. One exception is cytosine arabinoside (Ara-C) to which IALL cells seem to be more sensitive. We quantified mRNA expression of Ara-C key enzymes in leukemic lymphoblasts from 64 Brazilian ALL children, 15 of them presenting MLL gene rearrangement, and correlated it with clinical and biological features. The diagnosis was based on morphological criteria and immunophenotyping using monoclonal antibodies. MLL gene rearrangements were detected by conventional cytogenetic analysis, RT-PCR and/or fluorescence in situ hybridization. The DCK and HENT1 expression levels were determined by real-time quantitative PCR using SYBR Green I. Relative quantification was made by the standard curve method. The results were analyzed by Mann-Whitney and Fisher exact tests. A P value of ú0.05 was considered to be statistically significant. DCK and HENT1 expression levels were significantly lower in children with MLL gene-rearranged ALL compared to children with MLL germ line ALL (P = 0.0003 and 0.03, respectively). Our results differ from previous ones concerning HENT1 mRNA expression that observed a higher expression level in MLL gene-rearranged leukemias. In conclusion, the expression of the genes related to Ara-C metabolism was lower in MLL-positive children in the sample studied, suggesting the presence of population differences in the expression profile of these genes especially for HENT1.