Aromatic profiles and enantiomeric distributions of chiral odorants in baked green teas with different picking tenderness.

Suitable picking tenderness is an essential prerequisite for manufacturing tea. However, the influence of picking tenderness of fresh tea leaves on the aromatic components is still unclear. In this study, aromatic profiles and chiral odorants in fresh tea leaves and corresponding baked green teas with five levels of tenderness of two representative cultivars were analysed using stir bar sorptive extraction-gas chromatography-mass spectrometry. cis-Linalool oxide (furanoid) and methyl salicylate exhibited significantly increasing trends as samples of all series matured. The content of most chiral odorants was significantly high in the mature samples, and significant content variations of all enantiomers during baked green tea processing could be observed with different trends according to their precursors. In particular, the enantiomeric ratios of most chiral odorants were less influenced by the picking tenderness and processing, while drying (limonene), spreading and fixation (α-terpineol), and spreading (dihydroactinidiolide) influenced the chiral distribution of the aforementioned odorants.

Assessment of the contribution of chiral odorants to aroma property of baked green teas using an efficient sequential stir bar sorptive extraction approach.

Chiral volatile compounds are known to be distributed in teas at various enantiomeric ratios. However, the performance of each enantiomer, including aroma characteristics, aroma intensities, and contribution to the overall flavor of tea, is still unclear. In this study, aroma characteristics and intensities of 38 volatile enantiomers in standards and baked green teas with chestnut-like aroma and clean aroma were evaluated by an efficient sequential headspace-stir bar sorptive extraction (seq-HS-SBSE) approach combined with the enantioselective gas chromatography-olfactometry/mass spectrometry (Es-GC-O/MS) technique. Moreover, aroma recombination results for the two types of baked green teas using 14 chiral odorants and four achiral odorants indicated that the combinations of the detected odorants mainly contributed to the "floral", "sweet", and "chestnut-like" aromas. R-Linalool simultaneously enhanced the "floral", "sweet", and "chestnut-like" aromas; R-limonene mainly contributed to the "sweet" and "clean" aromas; and S-α-terpineol promoted the "sweet" and "floral" aromas of baked green tea.

Vogesella urethralis sp. nov., isolated from human urine, and emended descriptions of Vogesella perlucida and Vogesella mureinivorans.

A novel Vogesella strain, YM-1T, was recovered from human urine in PR China in 2017. Cells of strain YM-1T were Gram-stain-negative, rod-shaped, aerobic, motile, non-spore-forming and poly-ß-hydroxybutyrate-accumulating. The strain contained C16:1ω6c/C 16:1ω7c, C16:0 and C18:0ω7c as major fatty acids; phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and an unidentified phospholipid as major polar lipids; and ubiquinone-8 as the predominant respiratory quinone. Comparison of 16S rRNA gene sequences indicated that this strain had highest similarities to Vogesella perlucida DS-28T (98.8 %) and Vogesella mureinivorans 389T (98.1 %). The results of phylogenetic analysis based on the 16S rRNA gene sequences revealed that the novel strain was clustered and well separated with V. perlucida DS-28T and V. mureinivorans 389T within the genus Vogesella. The average nucleotide identity (ANI) and amino acid identity (AAI) analyses showed that this strain was not identified as V. perlucida DS-28T or V. mureinivorans 389T, with values well below the threshold limit for species demarcation (ANI <88.1 %, AAI <88.6 %). Based on the above results, strain YM-1T is proposed to be a novel species of the genus Vogesella with the name Vogesella urethralis sp. nov. (YM-1T=NBRC 113779=CGMCC 1.17135).

Genome-wide identification and characterization of ALTERNATIVE OXIDASE genes and their response under abiotic stresses in Camellia sinensis (L.) O. Kuntze.

MAIN CONCLUSION: Four typical ALTERNATIVE OXIDASE genes have been identified in tea plants, and their sequence features and gene expression profiles have provided useful information for further studies on function and regulation. Alternative oxidase (AOX) is a terminal oxidase located in the respiratory electron transport chain. AOX catalyzes the oxidation of quinol and the reduction of oxygen into water. In this study, a genome-wide search and subsequent DNA cloning were performed to identify and characterize AOX genes in tea plant (Camellia sinensis (L.) O. Kuntze cv. Longjing43). Our results showed that tea plant possesses four AOX genes, i.e., CsAOX1a, CsAOX1d, CsAOX2a and CsAOX2b. Gene structure and protein sequence analyses revealed that all CsAOXs share a four-exon/three-intron structure with highly conserved regions and amino acid residues, which are necessary for AOX secondary structures, catalytic activities and post-translational regulations. All CsAOX were shown to localize in mitochondria using the green fluorescent protein (GFP)-targeting assay. Both CsAOX1a and CsAOX1d were induced by cold, salt and drought stresses, and with different expression patterns in young and mature leaves. Reactive oxygen species (ROS) accumulated strongly after 72 and 96 h cold treatments in both young and mature leaves, while the polyphenol and total catechin decreased significantly only in mature leaves. In comparison to AtAOX1a in Arabidopsis thaliana, CsAOX1a lost almost all of the stress-responsive cis-acting regulatory elements in its promoter region (1500 bp upstream), but possesses a flavonoid biosynthesis-related MBSII cis-acting regulatory element. These results suggest a link between CsAOX1a function and the metabolism of some secondary metabolites in tea plant. Our studies provide a basis for the further elucidation of the biological function and regulation of the AOX pathway in tea plants.

Sub-inhibitory concentrations of fluoroquinolones increase conjugation frequency.

Bacteria are subjected to sub-minimal inhibitory concentrations (sub-MIC) of antibiotics in various niches where the low-dosage treatment plays a key role in antibiotic resistance selection. However, the mechanism of sub-MIC of antibiotics on the resistant gene transfer is largely unknown. Here, we used Escherichia coli SM10λpir in which the RP4 plasmid was chromosomally-integrated as the donor strain, to investigate the effects of sub-MIC of Ciprofloxacin(Cip) or Levofloxacin(Lev) on conjugational transfer of mobilisable plasmid-pUCP24T from SM10λpir to Pseudomonas aeruginosa. The results showed that the transfer frequency was significantly increased by treating E. coli with sub-MIC of Cip or Lev. To investigate the molecular mechanisms, complete transcriptome sequencing was performed. We found that the sub-MIC of Cip or Lev enhanced the expression of several genes on the RP4 plasmid, which was consistent with the conjugation efficiency. Moreover, the expression of genes associated with SOS response in donor SM10λpir was increased, but had no correlation with conjugation efficiency. These findings suggested that sub-MIC of Cip or Lev may promote conjugational transfer by up-regulating the expression of conjugation associated genes via an SOS-independent mechanism.

The fate of recent duplicated genes following a fourth-round whole genome duplication in a tetraploid fish, common carp (Cyprinus carpio).

Whole genome duplication (WGD) results in extensive genetic redundancy. In plants and yeast, WGD is followed by rapid gene deletions and intense expression differentiation with slow functional divergence. However, the early evolution of the gene differentiation processes is poorly understood in vertebrates because almost all studied WGDs are extremely ancient, and the genomes have returned to a diploid status. Common carp had a very recent fourth round of WGD dated to 8 million years ago. It therefore constitutes an ideal model to study early-stage functional divergence and expression differentiation in vertebrates. We identified 1,757 pairs of recently duplicated genes (RDGs) originating from this specific WGD and found that most ancestral genes were retained in duplicate. Most RDGs were conserved and under selective pressure. Gene expression analysis across six tissues revealed that 92.5% of RDG pairs were co-expressed in at least one tissue and that the expression of nearly half pairs ceased to be strongly correlated, indicating slow spatial divergence but rapid expression dissociation. Functional comparison revealed that 25% of pairs had functional divergence, of which neo- and sub-functionalization were the main outcomes. Our analysis revealed slow gene loss but rapid and intense expression and function differentiation after WGD.

[Efficacy of sublingual immunotherapy with dermatophagoides farinae drops in monosensitized and polysensitized patients with allergic rhinitis].

OBJECTIVE: To compare the efficacy of sublingual immunotherapy (SLIT) with standardized Dermatophagoides farinae drops in monosensitized and polysensitized patients with allergic rhinitis. METHODS: The efficacy of SLIT in 69 patients who were sensitized to house dust mites and treated with Dermatophagoides farinae drops for 1.5-2.0 year with complete clinical data were analyzed retrospectively. These patients had been divided into the monoallergen sensitized group and polyallergen sensitized group according to the results of skin prick tests. The total medication score (TMS) and the total nasal symptoms score (TNSS) were evaluated before and half an year, 1.0 year and 1.5-2.0 years after SLIT treatment. RESULTS: After SLIT treatment for half an year, the TNSS in the monoallergen sensitized group (2.00 [1.00; 3.00]) was significantly lower than that in the polyallergen sensitized group (3.00 [2.00; 4.00], Z = -2.851, P < 0.05), this significant difference of TNSS between the two groups was also found after SLIT treatment for 1.0 year (0.00 [0.00; 1.00], 2.00 [0.00; 3.00], Z = -2.590, P < 0.05). Whereas, there was no significant difference between the two groups after 1.5-2.0 years treatment refer to the TNSS (0.00 [0.00; 1.00], 0.00 [0. 00; 2.00], Z = -1.461, P > 0.05). Half an year, 1.0 year and 1.5-2.0 years after SLIT treatment, the TMS in both groups reduced significantly, with no significant difference between two groups (Z value was - 0.777, -0.944, -0.907, all P > 0. 05). CONCLUSIONS: SLIT with Dermatophagoides farinae drops is effective in monosensitized and polysensitized patients with allergic rhinitis. And equivalent efficacy could be achieved after 1.5-2.years.

TAT-CC fusion protein depresses the oncogenicity of BCR-ABL in vitro and in vivo through interrupting its oligomerization.

Chronic myeloid leukemia (CML) is a clonal hematologic malignancy characterized by the BCR-ABL protein. BCR-ABL is a constitutively active tyrosine kinase and plays a critical role in the pathogenesis of CML. Imatinib mesylate, a selective tyrosine kinase inhibitor, is effective in CML, but drug resistance and relapse occur. The coiled-coil (CC) domain located in BCR(1-72) mediates BCR-ABL tetramerization, which is essential for the activation of tyrosine kinase and transformation potential of BCR-ABL. CC domain is supposed to be a therapeutic target for CML. We purified a TAT-CC protein competively binding with the endogenous CC domain to reduce BCR-ABL kinase activity. We found that TAT-CC co-located and interacted with BCR-ABL in Ba/F3-p210 and K562 cells. It induced apoptosis and inhibited proliferation in these cells. It increased the sensitivity of these cells to imatinib and reduced the phosphorylation of BCR-ABL, CRKL and STAT5. We confirmed that TAT-CC could attenuate the oncogenicity of Ba/F3-p210 cells and diminish the volume of K562 solid tumor in mice. We conclude targeting the CC may provide a complementary therapy to inhibit BCR-ABL oncogenicity.

[Human CD96 gene cloning, expression and identification].

OBJECTIVE: To construct and express human CD96 gene outer membrane domain (hCD96om) in prokaryotic cells and prepare rabbit polyclonal antibody of hCD96om. METHODS: hCD96om was amplified by RT-PCR from the peripheral blood of patients with acute myeloid leukemia and inserted into prokaryotic expression vector pET32a(+) to construct the recombinant plasmid pET32-CD96. The expression of hCD96om was induced by IPTG in BL21(DE3) cells, and the expression product was identified by Western blotting. The anti-hCD96 polyclonal antibody was prepared by immunization of rabbits with the fusion protein. The specificity of anti-hCD96 antibody was determined by Western blotting. RESULTS: hCD96om protein was expressed in E.coli BL21(DE3) cells in the form of inclusion body, with a relative molecular mass around 37 kD. Western blotting showed a specific reaction of the prepared antiserum with the 70 kD protein extracted from human leukemia cell line HL-60 cells and with the 37 kD hCD96om fusion protein. CONCLUSION: The CD96 gene of human has been successfully cloned and expressed in BL21(DE3) cells, and its rabbit polyclonal antibody has been obtained.

Selective leukemia cell death by activation of the double-stranded RNA-dependent protein kinase PKR.

Deregulated activity of the BCR-ABL tyrosine kinase encoded by the Bcr-Abl oncogene represents an important therapeutic target for all the chronic myelogenous leukemia (CML) phases. In this study, we sought to identify targeted PKR activation by Bcr-Abl AS RNA, an anti-sense RNA complementary to the unique mRNA fragments flanking the fusion point of Bcr-Abl, which can be used as an effective anti-leukemia strategy in K562 cells. Moreover, we observed expression of Bcr-Abl AS RNA in K562 cells which resulted in selective apoptosis induction through specific activation of PKR, leading to phosphorylation of eIF2α, global inhibition of protein synthesis, caspase-8 activation and BAX up-regulation. The targeted PKR activation and induced apoptosis were reversed by the PKR inhibitor 2-aminopurine. Taken together, our results indicate that targeted PKR activation led to selective apoptosis induction in K562 cells, which correlated with caspase-8 activity and enhanced expression of BAX.

[Study on identification and traceability of tea material cultivar by combined analysis of multi-partial least squares models based on near infrared spectroscopy].

The present study attempted to achieve the identification and traceability of tea material cultivar through combination of multi-partial least squares models and Euclidean distance, etc. The results indicate that with the samples manufactured with tea fresh leaves of cultivar Longjing 43, Qunti, Yingshuang and Wuniuzao as the analysis objects, 4 models were established in this study so as to identify the tea with material cultivar being tea fresh leaves of cultivar Longjing 43, Qunti, Yingshuang and Wuniuzao separately by PLS. Their accuracy rate of identification of samples in the calibration set were 89.8%, 90.9%, 96.1% and 99.5%, respectively, while those in test set were 87.1%, 84.2%, 96.1% and 97.5%, respectively. After the "first identification" through the combined analysis of the four models for identification of tea material cultivar and the "second identification" adopting the Euclidean distance, the accuracy rate of material cultivar recognition for the tea samples was 90.3% (calibration set) and 83.5% (test set), respectively. This study provided a reference method for the identification of tea manufactured with a specific material cultivar and the material cultivar traceability of the manufactured tea.

Per2 inhibits k562 leukemia cell growth in vitro and in vivo through cell cycle arrest and apoptosis induction.

Per2 regulates other molecular and biochemical processes beyond their established role in the regulation of the mammalian circadian clock, herein we investigated the growth inhibiting potential of Per2 in human K562 leukemia cells and the underlying mechanisms. The results showed that over-expression of Per2 induced not only cell cycle arrest at G2/M phase but also an increase in apoptosis, which was confirmed by characteristic morphological changes, FCM and evident DNA fragmentation. Further experiments confirmed both up-regulation of P53 and down-regulation of CylinB1and C-myc. On the other hand, while P53 was found to be down-regulated. CylinB1 and C-myc were up-regulated. after Per2 knockdown. In leukemia mice, Per2 transfection was shown to suppress cellular proliferation and accelerate apoptosis of K562 cells. Moreover, fewer leukemia cells were found to have infiltrated into the livers and spleens of the mice from the Per2 transfected group as compared with those from the control group. In summary, Per2 displayed a significant anti-tumor effect through cell cycle arrest and apoptosis induction in K562 cells. These data further support the emerging role of the circadian clock in critical aspects of cancer development and thorough research is underway on the mechanism of Per2 in the leukemia.

Cloning, expression, purification, distribution and kinetics characterization of the bacterial beta-galactosidase fused to the cytoplasmic transduction peptide in vitro and in vivo.

Cytoplasmic transduction peptide (CTP) offers exciting therapeutic opportunities for the treatment of many diseases caused by cytoplasmic functional molecules. It can transduce large, biologically active proteins into the cytoplasmic compartment of several mammalian cells. However, other intriguing features of CTP, including its activity in vitro, and distribution and tissue infiltration abilities in vivo, remain to be explored. The present study was initiated to (1) further confirm the cytoplasmic localization preference and the enzymatic activity of the transduced CTP-beta-gal in vitro and (2) examine the kinetics and tissue distribution of the CTP-beta-gal fusion protein in mice. A CTP-beta-gal fusion protein was expressed in Escherichia coli and either transduced into BaF3-BCR/ABL cells or administered intravenously into female Balb/C mice at a dose of 100 microg per mouse. Its localization in BaF3-BCR/ABL cells was evaluated by immunocytochemistry and in situ X-gal staining, and its distribution in various tissues was analyzed both by in situ X-gal staining and quantitative enzymatic activity assay. beta-Galactosidase enzyme activity was observed in BaF3-BCR/ABL cells and in all tissues tested, with peak activity occurring at 15 min in most tissues and at 24h in brain. These data will not only allow rational selection of delivery schedules for therapeutic CTP, but will also aid the use of CTP fusion protein transduction in the development of protein therapeutics targeting the cytoplasmic compartment both in vitro and in vivo.

Cloning, expression, purification and functional characterization of the oligomerization domain of Bcr-Abl oncoprotein fused to the cytoplasmic transduction peptide.

Protein-based cellular therapeutics have been limited by getting molecules into cells and the fact that many proteins require accurate cellular localization for function. Cytoplasmic transduction peptide (CTP) is a newly designed transduction peptide that carries molecules across the cell membrane with a preference to localize in the cytoplasmic compartment and is, therefore, applicable for cytoplasmic targeting. The Bcr-Abl fusion protein, playing major causative role in chronic myeloid leukemia (CML), is a cytoplasmic oncoprotein that contains an N-terminus oligomerization domain (OD) mediating homodimerization of Bcr-Abl proteins, and an intact OD in Bcr-Abl is required both for the activation of its transforming activity and tyrosine kinase. Therefore, disrupting Bcr-Abl oligomerization represents a potential therapeutic strategy for inhibiting Bcr-Abl oncogenicity. In this study, we explored the possible homodimerization-disrupting and tyrosine kinase inhibiting effect of the transduction of OD in Bcr-Abl positive K562 cells. By expressing in Escherichia coli a CTP-OD-HA fusion protein followed by Ni+-NTA affinity purification, immunoblot identification and enterokinase cleavage, we showed that the CTP-OD-HA protein was structurally and functionally active in that it potently transduced and primarily localized into the cytoplasmic compartment, heterodimerized with Bcr-Abl, and potently inhibited the phospho-tyrosine pathways of Bcr-Abl oncoprotein at a low concentration of 4 microM. These results delineate strategies for the expression and purification of therapeutic molecules for intracytoplasmic protein based therapeutics and the CTP-OD-HA-mediated killing strategy could be explored as a promising anti-leukemia agent or an adjuvant to the conventional therapeutic modalities in chronic myeloid leukemia, such as in vitro purging.

[Targeted blockage of RNA binding protein E2 by decoy RNA induces the granulocytic differentiation of K562 cells].

OBJECTIVE: To use a decoy RNA targeted blockage of the RNA binding protein E2 (hnRNP E2) resulting in the CCAAT/enhancer-binding protein alpha (C/EBP alpha) gene's abnormal translation and investigate its effect on the granulocytic differentiation of K562 cells and the probable molecular mechanism. METHODS: The hnRNP E2 decoy RNA expression plasmid was constructed and transfected into K562 cells with cationic liposome, and stable expression cells were obtained by G418 selection. The changes of C/EBP alpha and granulocyte colony-stimulating factor receptor (G-CSFR) gene expression were detected by RT-PCR and Western blot. The morphologic changes were observed after Wright-Giemsa staining. The expression of granulocytic differentiation antigens CD13 and CD15 was studied by immunocytochemistry. RESULTS: The stably expressed pG cells were obtained. Its C/EBP alpha mRNA level remained unchanged, while 42kD-C/EBP alpha protein expression was increased by (49.7 +/- 5.5)% (P < 0.05); and G-CSFR mRNA was increased by (42.1 +/- 3.6)% (P < .05), and its protein was increased by (37.4 +/- 6.2)% (P < 0.05) compared to that in the K562 control cells. The characteristics of polymorphonuclear neutrophils appeared in pG cells and CD13 and CD15 positive cell ratios were (18.7 +/- 2.5)% and (26.3 +/- 2.9)% respectively. CONCLUSIONS: HnRNP E2 decoy RNA can induce granulocytic differentiation of K562 cells, and G-CSF promotes this effect. The mechanisms may be that decoy RNA specifically blocks hnRNP E2, hence regulates the translation of C/ EBP alpha mRNA, restores the expression of 42kD-C/EBP alpha, and then up-regulates the expression of G-CSFR gene.

[Effect of targeted activation of protein kinase PKR on proliferation of leukemia cell line K562 and its mechanism].

BACKGROUND & OBJECTIVE: The bcr-abl fusion gene induced by reciprocal translocation of t(9; 22)(q34; q11) plays an important role in pathogenesis of chronic myeloid leukemia (CML). Using the strategy of activating double-stranded RNA (dsRNA)-dependent protein kinase (PKR) by the dsRNA formed between the CML-specific bcr/abl fusion gene mRNA and the exogenous recombinant antisense RNA, this study was to investigate the effect of the activated PKR on the proliferation of leukemia cell line K562, and explore its possible mechanisms. METHODS: dsRNA analogue polyriboinosinic polyribocytidylic acid (PolyIC), retroviral vector containing 40 bp of bcr/abl fusion gene sequence (RV-40AS), RV-40AS and 2-aminopurine (2-AP), and retroviral vector containing green fluorescent protein sequence (RV-GFP) were transfected or infected into K562 cells respectively; ECV304 cells were used as control. Cell proliferation was determined by cell counting, MTT assay, and semisolid clone formation experiment. Cell cycle was analyzed by flow cytometry (FCM). The expression of PKR, phosphated PKR (p-PKR), eukaryotic initiation factor-2alpha (eIF2alpha), and phosphated eIF2alpha (p-eIF2alpha) was detected by Western blot. Total protein synthesis was studied by 3H-leucine incorporation. RESULTS: polyIC inhibited the proliferation of K562 cells and ECV304 cells unspecifically, while RV-40AS only inhibited the proliferation of K562 cells specifically. 2-AP blocked the inhibitory effect of RV-40AS on the proliferation of K562 cells. The S phase proportion was significantly lower in polyIC-and RV-40AS-treated K562 cells than in untreated cells [(37.26+/-2.35)% and (31.48+/-3.65)% vs. (58.53+/-5.42)%, P<0.05], while the G0/G1 phase proportion was significantly higher in polyIC-and RV-40AS-treated cells than in untreated cells [(50.97+/-2.18)% and (57.47+/-3.61)% vs. (36.44+/-4.20)%, P<0.05]. The expression of p-PKR and p-eIF2alpha in polyIC-and RV-40AS-treated K562 cells and polyIC-treated ECV304 cells was obviously up-regulated. The total protein synthesis level was significantly lower in RV-40AS-treated K562 cells than in untreated K562 cells [(3.5+/-1.9) cpm/ng vs. (26.8+/-2.6) cpm/ng, P<0.05]. CONCLUSION: Targeted activation of PKR could inhibit the proliferation of K562 cells through inhibiting protein synthesis, and arresting progression of cell cycle.

[Effect and possible mechanism of HnRNP E2 decoy RNA on proliferation of K562 leukemia cells].

BACKGROUND & OBJECTIVE: The abnormal expression of poly(rC)-binding protein E2 (hnRNP E2) induced by BCR/ABL plays an important role in blast crisis of chronic myeloid leukemia (CML). The present study was to investigate the effect of hnRNP E2 decoy RNA on the cell proliferation in K562 leukemia cells, and further elucidate the possible underlying mechanisms. METHODS: Decoy hnRNP E2 plasmid was constructed and transfected into K562 cells using cationic liposome. Stably transfected cells were selected with G418. The cell proliferation rate was determined by cell growth curve using trypan blue staining, and the cell cycle was analyzed by flow cytometry. The changes of CCAAT/enhancer-binding protein alpha (C/EBP alpha) and c-Myc gene expression were detected by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. RESULTS: The proliferation rate of stably transfected K562 cells was inhibited by (62.73+/-12.92)%. The cell cycle was arrested at S phase [stably transfected K562 cell group: (55.59+/-4.67)%, control group: (44.70+/-4.21)%, P<0.05]; C/EBPalpha mRNA level remained unchanged. However the 42 ku-C/EBPalpha protein expression was elevated by (49.72+/-5.58)%; c-Myc mRNA and protein expression was inhibited by (58.27+/-7.23)% and (57.26+/-6.52)%, respectively. CONCLUSION: HnRNP E2 decoy RNA could inhibit the proliferation of K562 cells, and this may be caused by the blockage of the binding between hnRNP E2 and C/EBPalpha mRNA and subsequent elevation of 42 ku-C/EBPalpha by decoy RNA.

[Regulatory effect of STAT5 decoy oligonucleotides on trans-activation of bcl-x gene promoter in K562 cells].

BACKGROUND & OBJECTIVE: Constitutive activation of signal transducers and activators of transcription 5 (STAT5) plays an important role in malignant transformation of chronic myeloid leukemia (CML) cells. This study was to explore regulatory effect of STAT5 decoy oligonucleotides (ODNs) on trans-activation of its downstream target bcl-x gene in K562 cells. METHODS: STAT5 decoy ODNs, mismatched ODNs (M-ODNs), and FAM-decoy ODNs were designed and synthesized. FAM-decoy ODNs were used as control, and transfected into K562 cells by cationic liposomes, analyzed by flow cytometry (FCM) and fluorescent inversive microscopy. The bcl-x promoter fragment acquired by polymerase chain reaction (PCR) was inserted into pGL3-basic to construct luciferase report plasmid pGL3b-bclxp, which was co-transfected with decoy ODNs or M-ODNs into K562 cells. The activity of luciferase was detected. After transfection of decoy ODNs, and M-ODNs, expression of bcl-xL mRNA in K562 cells was detected by reverse transcription-PCR (RT-PCR),cell apoptosis was detected by FCM. RESULTS: FAM-decoy ODNs were incorporated into K562 cells in a dose-dependent manner. The incorporation efficiency reached 99.1% at the concentration of 4 micromol/L 24 h after transfection, and green fluorescence could be observed in cells under fluorescent inversive microscope. The luciferase activity was significantly lower in STAT5 decoy ODNs group than in control group [(181.48+/-204.46) RLU/microg protein vs. (675.26+/-62.91) RLU/mug protein, P < 0.05], but that of M-ODNs group [(632.07+/-98.95) RLU/microg protein] has no significant difference with that of control group (P > 0.05). mRNA level of bcl-xL was decreased by STAT5 decoy ODNs, but not by M-ODNs. Moreover, Sub G1 peak was detected in STAT5 decoy ODNs group by FCM. CONCLUSION: Transfection of STAT5 decoy ODNs can down-regulate the trans-activation of bcl-x in K562 cells.

[Targeted blockage of STAT5 by a decoy oligodeoxynucleotide inhibits the growth and proliferation of K562 cells].

OBJECTIVES: To investigate targeted blockage of BCR/ABL oncoprotein mediated cell transformation by STAT5 decoy oligodeoxynucleotide (ODN), its effect on the growth and proliferation inhibition of K562 cells and the related molecular mechanisms. METHODS: STAT5 decoy ODN, designed and synthesized in vitro, was transfected into K562 cells by cationic lipid. The cell growth curve and colony formation assay were used to reflect the growth and proliferation capacity of K562 cells, RT-PCR to detect the expression of three genes downstream STAT5. RESULTS: Confocal microscopy demonstrated that STAT5 decoy ODN was successfully transfected into K562 cells (95.2% positive cells). STAT5 decoy ODN inhibited the growth of K562 cells (inhibition rate 77.7%) and their colony formation capacity (Decoy ODN treated group 8.3% vs control group 35.7%, P < 0.05) after the treatment with STAT5 decoy ODN, the expressions of c-myc, bcl-X(L), cyclin D1 mRNA were down-regulated by 15.4%, 30.8%, 29.1%, respectively in the K562 cells. CONCLUSIONS: STAT5 decoy ODN inhibits the growth and proliferation of K562 cells. The mechanisms may be that decoy ODN blocks the transcriptional activation potent of STAT5 and down-regulates the expression of these tumor related genes downstream STAT5.