G-Quadruplexes in Repeat Expansion Disorders.

The repeat expansions are the main genetic cause of various neurodegeneration diseases. More than ten kinds of repeat sequences with different lengths, locations, and structures have been confirmed in the past two decades. G-rich repeat sequences, such as CGG and GGGGCC, are reported to form functional G-quadruplexes, participating in many important bioprocesses. In this review, we conducted an overview concerning the contribution of G-quadruplex in repeat expansion disorders and summarized related mechanisms in current pathological studies, including the increasing genetic instabilities in replication and transcription, the toxic RNA foci formed in neurons, and the loss/gain function of proteins and peptides. Furthermore, novel strategies targeting G-quadruplex repeats were developed based on the understanding of disease mechanism. Small molecules and proteins binding to G-quadruplex in repeat expansions were investigated to protect neurons from dysfunction and delay the progression of neurodegeneration. In addition, the effects of environment on the stability of G-quadruplex were discussed, which might be critical factors in the pathological study of repeat expansion disorders.

Ginsenoside Compound K Assisted G-Quadruplex Folding and Regulated G-Quadruplex-Containing Transcription.

Ginsenoside compound K (CK) is one of the major metabolites of the bioactive ingredients in Panax ginseng, which presents excellent bioactivity and regulates the expression of important proteins. In this work, the effects of CK on G-quadruplexes (G4s) were quantitatively analyzed in the presence and absence of their complementary sequences. CK was demonstrated to facilitate the formation of G4s, and increase the quantity of G4s in the competition with duplex. Thermodynamic experiments suggested that the electrostatic interactions were important for G4 stabilization by CK. CK was further found to regulate the transcription of G4-containing templates, reduce full-length transcripts, and decrease the transcription efficiency. Our results provide new evidence for the pharmacological study of ginsenosides at the gene level.

RNA G-Quadruplexes Facilitate RNA Accumulation in G-Rich Repeat Expansions.

The regulatory mechanisms of the processes of RNA accumulation were examined from a chemical perspective in repeat-expansion disorders, which induce cytotoxicity and cause neurodegenerative diseases. We found that the accumulation, including production, gelation, and sedimentation, of RNA repeats transcribed from repeat expansions related to neurodegenerative diseases was greatly accelerated by G-quadruplex-forming RNA repeats, although no acceleration was induced by hairpin-forming RNA repeats. We also investigated the relationship between accumulation and physical solution properties, such as viscosity and water activity, and found that RNA accumulation was promoted through a decrease in the dielectric constant. Importantly, we found that the RNA accumulation required RNA G-quadruplexes and was promoted by changes in the dielectric property of the cell induced by an ion channel inhibitor. Our study is the first to show that the accumulation processes that induce toxicity in cells can be controlled via electrostatic interactions in the RNA G-quadruplex; thus, these can form the basis of guidelines for the chemical control of cell toxins.

Effect of Potassium Concentration on Triplex Stability under Molecular Crowding Conditions.

The properties of non-canonical DNA structures, like G-quadruplexes and triplexes, change under cell-mimicking molecular crowding conditions relative to dilute aqueous solutions. The analysis of environmental effects on their stability is crucial since they play important roles in gene expression and regulation. In this study, three intramolecular and intermolecular triplex-forming sequences of different C+*G-C triplet content (*: Hoogsteen base pair; - : Watson-Crick base pair) were designed and their stability measured in the absence and presence of a crowding agent with different K+ concentrations. In dilute solution, the stability of the triplexes was reduced by decreasing the concentration of KCl. This reduction became smaller as the number of C+*G-C triplets increased. Under molecular crowding conditions, Watson-Crick base pairs and Hoogsteen base pairs were destabilized and stabilized, respectively. Interestingly, with lower KCl concentrations (≤1 M), the destabilization of the triplexes due to reduction of KCl concentration was significantly smaller than in dilute solutions. In addition, the C+*G-C content had greater influence on triplex stability under molecular crowding conditions. Our work provides quantitative information about the effects of K+ concentration on triplex stability under molecular crowding conditions and should further our understanding of the function and regulation of triplexes in bioprocesses.

Drastic stability change of X-X mismatch in d(CXG) trinucleotide repeat disorders under molecular crowding condition.

The trinucleotide repeat d(CXG) (X = A, C, G or T) is the most common sequence causing repeat expansion disorders. The formation of non-canonical structures, such as hairpin structures with X-X mismatches, has been proposed to affect gene expression and regulation, which are important in pathological studies of these devastating neurological diseases. However, little information is available regarding the thermodynamics of the repeat sequence under crowded cellular conditions where many non-canonical structures such as G-quadruplexes are highly stabilized, while duplexes are destabilised. In this study, we investigated the different stabilities of X-X mismatches in the context of internal d(CXG) self-complementary sequences in an environment with a high concentration of cosolutes to mimic the crowding conditions in cells. The stabilities of full-matched duplexes and duplexes with A-A, G-G, and T-T mismatched base pairs under molecular crowding conditions were notably decreased compared to under dilute conditions. However, the stability of the DNA duplex with a C-C mismatch base pair was only slightly destabilised. Investigating different stabilities of X-X mismatches in d(CXG) sequences is important for improving our understanding of the formation and transition of multiple non-canonical structures in trinucleotide repeat diseases, and may provide insights for pathological studies and drug development.

A Turn-On Detection of DNA Sequences by Means of Fluorescence of DNA-Templated Silver Nanoclusters via Unique Interactions of a Hydrated Ionic Liquid.

Nucleic acid stability and structure, which are crucial to the properties of fluorescent DNA-templated silver nanoclusters (DNA-Ag NCs), significantly change in ionic liquids. In this work, our purpose was to study DNA-Ag NCs in a buffer containing the hydrated ionic liquid of choline dihydrogen phosphate (choline dhp) to improve fluorescence for application in DNA detection. Due to the stabilisation of an i-motif structure by the choline cation, a unique fluorescence emission-that was not seen in an aqueous buffer-was observed in choline dhp and remained stable for more than 30 days. A DNA-Ag NCs probe was designed to have greater fluorescence intensity in choline dhp in the presence of a target DNA. A turn-on sensing platform in choline dhp was built for the detection of the BRCA1 gene, which is related to familial breast and ovarian cancers. This platform showed better sensitivity and selectivity in distinguishing a target sequence from a mutant sequence in choline dhp than in the aqueous buffer. Our study provides new evidence regarding the effects of structure on properties of fluorescent DNA-Ag NCs and expands the applications of fluorescent DNA-Ag NCs in an ionic liquid because of improved sensitivity and selectivity.

Hypodermin A improves survival of skin allografts.

BACKGROUND: Hypodermin A (HA) is a serine esterase that degrades complement, a key element of the innate immune system. Immunosuppressive properties of HA have previously been studied in vitro. However, such properties have not been fully demonstrated in vivo. The aim of this study was to evaluate the effect of HA in inhibiting allograft rejection in an HA transgenic mouse model. METHODS: FVB (HA transgenic mice or wild-type mice) to BALB/c mice skin transplantation model were used. Skin grafts were analyzed by histology, immunohistochemistry, and Western blotting. RESULTS: HA overexpression resulted in significantly prolonged skin allograft survival. Histologic changes in the skin allografts paralleled the gross appearance of rejection. ELISA and Western blotting showed that HA significantly reduced the content of complement C3 and C9 in HA skin allografts. The expressions of CD4, B7-2, and MHC class II were all significantly suppressed in HA skin allografts compared with the control group. CONCLUSIONS: These findings suggest that HA effectively prolongs skin allograft survival. The study results provide insight into a promising strategy to improve the survival of grafts in humans.

Ratiometric fluorescence detection of tyrosinase activity and dopamine using thiolate-protected gold nanoclusters.

In this work, a sensitive and selective ratiometric fluorescence sensing platform was built for the detection of tyrosinase (TYR) activity and dopamine (DA) using glutathione (GSH) protected gold nanoclusters (Au NCs) as probes. Upon excitation at 350 nm, Au NCs displayed an intense red emission, which could be effectively quenched by quinones. TYR, a typical polyphenol oxidase, can catalyze the oxidization of DA to o-quinone and therefore quenched the fluorescence of Au NCs. Moreover, the reaction of TYR and DA gave rise to an emission band at 400 nm, which increased in a TYR/DA-concentration-dependent manner. The ratiometric signal variations were utilized for facile, sensitive, and selective detection of TYR activity and DA. A linear range was obtained from 0.006-3.6 unit mL(-1) of TYR activity, while the linear range for detection of DA was 1.0 nM to 1.0 mM. Additionally, it constructed a useful platform for TYR inhibitor screening in biomedical research.

The relationship between DNA sequences and oligonucleotide-templated silver nanoclusters and their fluorescence properties.

A novel approach was developed to study the relationship between DNA sequences and DNA-templated silver nanoclusters (DNA-Ag NCs) in detail by using an ordinary DNA strand as an example. Three kinds of Ag NCs are formed by using the DNA strand as a scaffold. By dividing the DNA template into several parts according to their different affinities to Ag(+) , it was found that the fluorescence properties of DNA-Ag NCs are related to not only the sequences but also to the position of different parts in the template, which provides a more efficient approach to obtain DNA-Ag NCs with required photoluminescence properties and may ultimately contribute to the targeted synthesis of DNA-Ag NCs.

Effect of three oral pathogens on the TMA-TMAO metabolic pathway.

Background: Trimethylamine-N-oxide (TMAO) is produced by hepatic flavin-containing monooxygenase 3 (FMO3) from trimethylamine (TMA). High TMAO level is a biomarker of cardiovascular diseases and metabolic disorders, and it also affects periodontitis through interactions with the gastrointestinal microbiome. While recent findings indicate that periodontitis may alter systemic TMAO levels, the specific mechanisms linking these changes and particular oral pathogens require further clarification. Methods: In this study, we established a C57BL/6J male mouse model by orally administering Porphyromonas gingivalis (P. gingivalis, Pg), Fusobacterium nucleatum (F. nucleatum, Fn), Streptococcus mutans (S. mutans, Sm) and PBS was used as a control. We conducted LC-MS/MS analysis to quantify the concentrations of TMAO and its precursors in the plasma and cecal contents of mice. The diversity and composition of the gut microbiome were analyzed using 16S rRNA sequencing. TMAO-related lipid metabolism and enzymes in the intestines and liver were assessed by qPCR and ELISA methods. We further explored the effect of Pg on FMO3 expression and lipid molecules in HepG2 cells by stimulating the cells with Pg-LPS in vitro. Results: The three oral pathogenic bacteria were orally administered to the mice for 5 weeks. The Pg group showed a marked increase in plasma TMAO, betaine, and creatinine levels, whereas no significant differences were observed in the gut TMAO level among the four groups. Further analysis showed similar diversity and composition in the gut microbiomes of both the Pg and Fn groups, which were different from the Sm and control groups. The profiles of TMA-TMAO pathway-related genera and gut enzymes were not significantly different among all groups. The Pg group showed significantly higher liver FMO3 levels and elevated lipid factors (IL-6, TG, TC, and NEFA) in contrast to the other groups. In vitro experiments confirmed that stimulation of HepG2 cells with Pg-LPS upregulated the expression of FMO3 and increased the lipid factors TC, TG, and IL-6. Conclusion: This study conclusively demonstrates that Pg, compared to Fn and Sm, plays a critical role in elevating plasma TMAO levels and significantly influences the TMA-TMAO pathway, primarily by modulating the expression of hepatic FMO3 and directly impacting hepatic lipid metabolism.

BMSCs attenuate radiation-induced brain injury induced hippocampal neuronal apoptosis through a PI3K/Akt/Bax/Bcl-2 signaling pathway.

BACKGROUND: Bone marrow mesenchymal stem cell (BMSCs) -based therapies represent a promising treatment for neurological disorders. However, therapeutic effects and mechanisms of BMSCs transplantation for radiation-induced brain injury (RIBI) have not been fully disclosed. In this article, we explored the functions of BMSCs transplantation on RIBI and investigated the protective effects of BMSCS on hippocampal neurons in RIBI as well as the related molecular mechanisms. MATERIALS AND METHODS: 6-8 weeks-old rats were used to build a RIBI model. Rats in BMSC group were treated with a 3 × 106 BMSCs injection through the tail vein on the 1st day and 8th day after irradiation; rats in both control and RIBI groups were injected with an equivalent volume of physiological saline for comparisons. The Morris water maze was applied to detect the variations in cognitive function after RIBI. MRS was performed to test changes in NAA/Cr, indicating neuronal apoptosis after RIBI. TUNEL was conducted to detect apoptosis of rat hippocampal neurons, and HE staining was carried out to show pathological variations in the hippocampal region of rats. Protein levels of PI3K, P-PI3K, AKT, P-AKT, Bcl-2, and Bax proteins of rats in the hippocampal area were all determined by Western blot. RESULTS: Cognitive function was reduced and hippocampal neurons underwent apoptosis in the rats of the RIBI group, and cognitive abilities, histopathological alterations, and apoptosis of hippocampal neurons were significantly improved after BMSCs treatment; the expression of PI3K, P-PI3K, AKT, P-AKT, and Bcl-2 proteins, in the hippocampal region of the rat, was up-regulated, and Bax proteins were down-regulated. CONCLUSIONS: BMCSs can inhibit hippocampal neuronal apoptosis in RIBI, and the mechanism may be associated with the up-regulation of Bcl-2 and down-regulation of Bax by the PI3K/AKT signaling pathway.

Morphological changes in the cerebellum during aging: evidence from convolutional neural networks and shape analysis.

The morphology and function of the cerebellum are associated with various developmental disorders and healthy aging. Changes in cerebellar morphology during the aging process have been extensively investigated, with most studies focusing on changes in cerebellar regional volume. The volumetric method has been used to quantitatively demonstrate the decrease in the cerebellar volume with age, but it has certain limitations in visually presenting the morphological changes of cerebellar atrophy from a three-dimensional perspective. Thus, we comprehensively described cerebellar morphological changes during aging through volume measurements of subregions and shape analysis. This study included 553 healthy participants aged 20-80 years. A novel cerebellar localized segmentation algorithm based on convolutional neural networks was utilized to analyze the volume of subregions, followed by shape analysis for localized atrophy assessment based on the cerebellar thickness. The results indicated that out of the 28 subregions in the absolute volume of the cerebellum, 15 exhibited significant aging trends, and 16 exhibited significant sex differences. Regarding the analysis of relative volume, only 11 out of the 28 subregions of the cerebellum exhibited significant aging trends, and 4 exhibited significant sex differences. The results of the shape analysis revealed region-specific atrophy of the cerebellum with increasing age. Regions displaying more significant atrophy were predominantly located in the vermis, the lateral portions of bilateral cerebellar hemispheres, lobules I-III, and the medial portions of the posterior lobe. This atrophy differed between sexes. Men exhibited slightly more severe atrophy than women in most of the cerebellar regions. Our study provides a comprehensive perspective for observing cerebellar atrophy during the aging process.

Clinical study of different prediction models in predicting diabetic nephropathy in patients with type 2 diabetes mellitus.

BACKGROUND: Among older adults, type 2 diabetes mellitus (T2DM) is widely recognized as one of the most prevalent diseases. Diabetic nephropathy (DN) is a frequent complication of DM, mainly characterized by renal microvascular damage. Early detection, aggressive prevention, and cure of DN are key to improving prognosis. Establishing a diagnostic and predictive model for DN is crucial in auxiliary diagnosis. AIM: To investigate the factors that impact T2DM complicated with DN and utilize this information to develop a predictive model. METHODS: The clinical data of 210 patients diagnosed with T2DM and admitted to the First People's Hospital of Wenling between August 2019 and August 2022 were retrospectively analyzed. According to whether the patients had DN, they were divided into the DN group (complicated with DN) and the non-DN group (without DN). Multivariate logistic regression analysis was used to explore factors affecting DN in patients with T2DM. The data were randomly split into a training set (n = 147) and a test set (n = 63) in a 7:3 ratio using a random function. The training set was used to construct the nomogram, decision tree, and random forest models, and the test set was used to evaluate the prediction performance of the model by comparing the sensitivity, specificity, accuracy, recall, precision, and area under the receiver operating characteristic curve. RESULTS: Among the 210 patients with T2DM, 74 (35.34%) had DN. The validation dataset showed that the accuracies of the nomogram, decision tree, and random forest models in predicting DN in patients with T2DM were 0.746, 0.714, and 0.730, respectively. The sensitivities were 0.710, 0.710, and 0.806, respectively; the specificities were 0.844, 0.875, and 0.844, respectively; the area under the receiver operating characteristic curve (AUC) of the patients were 0.811, 0.735, and 0.850, respectively. The Delong test results revealed that the AUC values of the decision tree model were lower than those of the random forest and nomogram models (P < 0.05), whereas the difference in AUC values of the random forest and column-line graph models was not statistically significant (P > 0.05). CONCLUSION: Among the three prediction models, random forest performs best and can help identify patients with T2DM at high risk of DN.

Can G-quadruplex become a promising target in HBV therapy?

The chronic infection with hepatitis B virus (HBV) is an important health problem that affects millions of people worldwide. Current therapies for HBV always suffer from a poor response rate, common side effects, and the need for lifelong treatment. Novel therapeutic targets are expected. Interestingly, non-canonical structures of nucleic acids play crucial roles in the regulation of gene expression. Especially the formation of G-quadruplexes (G4s) in G-rich strands has been demonstrated to affect many bioprocesses including replication, transcription, and translation, showing great potential as targets in anticancer and antiviral therapies. In this review, we summarize recent antiviral studies about G4s and discuss the potential roles of G4 structures in antiviral therapy for HBV.

A nanocluster beacon based on the template transformation of DNA-templated silver nanoclusters.

In this work, we developed a novel light-up nanocluster beacon (NCB) based on shuttling dark silver nanoclusters (NCs) to a bright scaffold through hybridization. The fluorescence enhancement was as high as 70-fold when the two templates were on the opposite sides of the duplexes, enabling sensitive and selective detection of DNA.

[Transfection of HL-60 cells with CYP3A5 gene induces drug-resistant phenotype].

OBJECTIVE: To investigate if CYP3A5 gene is involved in the molecular mechanisms for multiple drug resistance in leukemia cells. METHODS: A full length cDNA of CYP3A5 gene was cloned, and a recombinant eukaryotic expression plasmid was constructed, then stably transfected cell lines were established. Furthermore, the sensitivity of those cell lines to several anticancer drugs were assessed by MTT and FCM assay. RESULTS: The recombinant plasmid was designated as pcDNA3-CYP3A5. Transfecting HL-60 cells (which didn't show transcript of CYP3A5 gene) with recombinant plasmid pcDNA3-CYP3A5 generated HL-60/CYP3A5 cell line, and transfecting of HL-60 cells with the parental pcDNA3 vector served as control HL-60/pc cell line. Daunorubicin induced remarkable apoptosis peaks in HL-60 and HL-60/pc cells, while such effect did not occur in HL-60/CYP3A5 cells (apoptosis cell percentage were 7.3%, 6.3% and 1.2%, respectively). Compared with HL-60 and HL-60/pc cells, HL-60/CYP3A5 cells were statistically significantly resistant to daunorubicin, aclacinomycin A, vincristine and harringtonine (resistance multiples were 2.89, 2.01, 4.05 and 2.79 times, respectively, P < 0.05), however the sensitivity to teniposide didn't change (resistance multiple was 1.04 times). CONCLUSION: Transcription of CYP3A5 gene in leukemia cells directly induces resistance to anthracyclines and alkaloids, however the cells are still sensitive to epipodophyllotoxins. Therefore, our findings confirmed a new mechanism of multidrug resistance.

[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.

A label-free fluorescent molecular beacon based on DNA-Ag nanoclusters for the construction of versatile Biosensors.

In this paper, we developed a simple, low-cost and sensitive DNA sequences detection biosensor based on a label-free molecular beacon (MB) whose DNA hairpin structure terminal has a guanine-rich sequence that can enhance fluorescence of silver nanoclusters (Ag NCs). Without hybridization between hairpin probe and target DNA, the Ag NCs presented bright fluorescence for the proximity of guanine-rich sequences (GRSs). After binding with target DNA, the hairpin shape was destroyed which results in a decrease of the Ag NCs fluorescence intensity. With this biosensor, we detected three disease-related genes that were the human immunodeficiency virus (HIV) gene, hepatitis B virus (HBV) gene and human T-lymphotropic virus type I (HTLV-I) gene. The detection limits based on S/N of 3 were 4.4 nM, 6.8 nM and 8.5 nM for HIV gene, HBV gene and HTLV-I gene, respectively. Our sensor was also of high selectivity and could distinguish even one nucleotide mismatched target.

G-quadruplex enhanced fluorescence of DNA-silver nanoclusters and their application in bioimaging.

Guanine proximity based fluorescence enhanced DNA-templated silver nanoclusters (AgNCs) have been reported and applied for bioanalysis. Herein, we studied the G-quadruplex enhanced fluorescence of DNA-AgNCs and gained several significant conclusions, which will be helpful for the design of future probes. Our results demonstrate that a G-quadruplex can also effectively stimulate the fluorescence potential of AgNCs. The major contribution of the G-quadruplex is to provide guanine bases, and its special structure has no measurable impact. The DNA-templated AgNCs were further analysed by native polyacrylamide gel electrophoresis and the guanine proximity enhancement mechanism could be visually verified by this method. Moreover, the fluorescence emission of C3A (CCCA)4 stabilized AgNCs was found to be easily and effectively enhanced by G-quadruplexes, such as T30695, AS1411 and TBA, especially AS1411. Benefiting from the high brightness of AS1411 enhanced DNA-AgNCs and the specific binding affinity of AS1411 for nucleolin, the AS1411 enhanced AgNCs can stain cancer cells for bioimaging.

[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.