Human Leukemia Cell Line K562 Research Articles

Divergolides T⁻W with Apoptosis-Inducing Activity from the Mangrove-Derived Actinomycete Streptomyces sp. KFD18.

Four new ansamycins, named divergolides T–W (1–4), along with two known analogs were isolated from the fermentation broth of the mangrove-derived actinomycete Streptomyces sp. KFD18. The structures of the compounds, including the absolute configurations of their stereogenic carbons, were determined by spectroscopic data and single-crystal X-ray diffraction analysis. Compounds 1–4 showed cytotoxic activity against the human gastric cancer cell line SGC-7901, the human leukemic cell line K562, the HeLa cell line, and the human lung carcinoma cell line A549, with 1 being the most active while compounds 5 and 6 were inactive against all the tested cell lines. Compounds 1 and 3 showed very potent and specific cytotoxic activities (IC50 2.8 and 4.7 µM, respectively) against the SGC-7901 cells. Further, the apoptosis-inducing effect of 1 and 3 against SGC-7901 cells was demonstrated by two kinds of staining methods for the first time.

Polyacetylenes from the Roots of Swietenia macrophylla King.

A phytochemical investigation of the roots of Swietenia macrophylla led to the isolation of seven polyacetylenes, including five new compounds (1–5) and two known ones (6–7). Their structures were elucidated by extensive spectroscopic analysis and detailed comparison with reported data. All the isolates were tested for their cytotoxicity against the human hepatocellular carcinoma cell line BEL-7402, human myeloid leukemia cell line K562, and human gastric carcinoma cell line SGC-7901. Compounds 1 and 6 showed moderate cytotoxicity against the above three human cancer cell lines with IC50 values ranging from 14.3 to 45.4 μM. Compound 4 displayed cytotoxicity against the K562 and SGC-7901 cancer cell lines with IC50 values of 26.2 ± 0.4 and 21.9 ± 0.3 μM, respectively.

Oleuropein reduces Prdx1 expression, cell proliferation and viability in K562 human leukemia cells

Oleuropein is one of the two main phenolic compounds derived from olive leaves. Numerous studies have found that the polyphenols contained in olive leaves possess strong antioxidant properties, and increase apoptosis in many types of cancer cells, suggesting its possible efficacy as an anti‐cancer treatments. The purpose of our study was to examine the effects of oleuropein extract on cell growth and viability of the K562 human leukemia cell line, and to investigate possible molecular mechanisms of action. Oleuropein of 98% purity was used for our studies. We first demonstrated that K562 cells treated with 200 and 400 μg/ml oleuropein exhibited a significant reduction in cell growth and viability after four days as compared to ethanol‐treated controls. Cells treated with 200μg/ml oleuropein showed decreased cell proliferation and viability after two days, and exhibited approximately 90% reduction in cell density and viability after four days of treatment. A concentration of 400 μg/ml oleuropein resulted in 100% toxicity by day four. We also examined the effects of oleuropein on cellular cytotoxicity using an LDH release assay and found a two‐fold elevation in LDH release within 24 hours of treatment with 200 μg/mL oleuropein. To begin to explore a mechanisms of action, we used western blotting to examine known antioxidant and signaling pathways for possible regulation by oleuropein in these cells. We examined expression of the Peroxiredoxin (Prdx) family of proteins, a group of thiol‐specific antioxidants found to be elevated in many types of cancer. We found that 200 ug/ml oleuropein reduced Prdx1 expression by about 50% after eight and twenty‐four hours, while having no significant effect on expression levels of Prdx‐2, ‐3, ‐4, and ‐6. We are currently investigating the mechanism of cell death induced by oleuropein, as well as the role of Prdx1 in oleuropein‐induced toxicity. Together with previously reported cancer‐cell specific effects, this research provides a promising new avenue for the use of natural products as anti‐cancer agents.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Undergraduate lab series using the K562 human leukemia cell line: Model for cell growth, death, and differentiation in an advanced cell biology course.

This sequence of labs was developed for an upper level undergraduate cell biology course at Fairfield University. The labs are based on the use of the K562 human erythroleukemia cell line, a model system that is exceptionally amenable to an undergraduate cell biology lab course due to its ease of maintenance and propagation and usefulness for studies of growth, death, and differentiation. The sequence of labs is conducted over a 6-week period, following a series of weekly cell biology labs covering basic cell and molecular biology techniques. Together, the lab series has four primary objectives 1) to teach students how to culture and maintain mammalian cells; 2) to build student competency in standard cell biology techniques; 3) to demonstrate the role of growth factors on cell proliferation and viability; and 4) to provide students with an opportunity to use these cells in an independent investigation on cell differentiation. We provide examples of student data and offer a range of experimental measurements depending on institutional capacity and facilities. Our assessment data suggest that students find great value in this lab series, enhancing their comprehension of key concepts, acquisition of important lab skills, and depth of understanding of the research process. © 2019 International Union of Biochemistry and Molecular Biology, 47(3):263-271, 2019.

Azaindole-BODIPYs: Synthesis, fluorescent recognition of hydrogen sulfate anion and biological evaluation.

The synthesized and sensing capability of two novel azaindole substituted mono and distyryl BODIPY dyes against bisulfate anion were reported. Structural characterizations of the targeted compounds were conducted by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, 1H and 13C NMR spectroscopies. Photophysical properties of the azaindole substituted BODIPY compounds were investigated employing absorption and fluorescence spectroscopies in acetonitrile solution. It was found that the final compounds 3 and 4 exhibited exclusively selective and sensitive turn-off sensor behavior on HSO4- anion. Additionally, the stoichiometry ratio of the targeted compounds to bisulfate anion was measured 0.5 by Job's method. Also, density function theory was performed to the optical response of the sensor for targeted compounds. Furthermore, the cytotoxicity of Azaindole-BODIPYs was examined against living human leukemia K562 cell lines.

Design, synthesis, and biological evaluation of 1,3,5-trisubstituted pyrazoles as tyrosine kinase inhibitors

We report herein, silica supported molybdic acid mediated oxidative C–N bond formation for the regioselective synthesis of new 1,3,5-trisubstituted pyrazole derivatives. This transformation furnishes a novel synthetic approach with solvent-free neat heat conditions, which was found to be flexible with wide substrate scope and better efficiency towards rapid synthesis of new 1,3,5-trisubstituted pyrazoles. Selected series of the synthesized derivatives were screened for their liability against carcinogenesis. A molecular docking study of the synthesized derivatives was performed in the active site of the tyrosine kinase enzymes. Based on the molecular docking study specific compounds were screened in vitro for their anticancer activity, which showed potent micro molar activity against human MDA-MB-231 breast cancer line and human leukemia cell line K-562 using 3-(4,5-dimethylthiazol-2-yl)–2, 5-diphenyltetrazolium bromide (MTT) assay. Compound 3l possesses higher inhibitory activity with IC50 0.58 ± 0.02 μM against the MDA-MB-231 cell line. Whereas compound 3k showed higher inhibitory activity with IC50 value 0.78 ± 0.03 μM against the K-562 cell line. Fluorescence microscopic studies revealed that the compounds showed late apoptotic mode of cell death. These results can lead to further exploitation of tested pyrazole compounds to the highly active drug molecule.

Heme Oxygenase-1/Ferritin in Protection of Leukemia Cells from Oxidative Stress Induced by Catalytic System “Teraphtal + Ascorbic Acid”

Background. As is well known, cytotoxic mechanism of antitumor agent, i.e. catalytic system “teraphtal + ascorbic acid” (“TF+AA”), is associated with production of reactive oxygen species (ROS) and induction of oxidative stress in it. The “heme oxygenase-1/ferritin” (HO-1/Ft) system contributes to antioxidant defense. Aim. To analyze HO-1/Ft value in protection of leukemia cells from toxicity induced by antitumor agent “TF+AA”. Materials & Methods. The study was based on human leukemia cell lines K562 and U937. HO-1/Ft basal and drug-induced expression on mRNA and protein levels was analyzed by real-time RT-PCR and Western blot, ROS concentration in cells was determined by flow cytometry, and drug cytotoxicity was measured by MTT assay. Results. Our data showed constitutively active HO-1 in U937 myelomonoblasts whereas in K562 erythroblasts the expression of this protein was blocked on the mRNA level. Hemin, HO-1 agonist, induces HO-1 and Ft co-expression in U937 cells on the mRNA and protein levels. HO-1/Ft activation by hemin in U937 cells does not affect their “TF+AA” sensitivity and doubles, for example, the cytarabine sensitivity. “TF+AA” appeared to cause up-regulation of HO-1/ Ft genes, the expression of which quadruples or increases by half, respectively, compared with basal level. Preincubation of U937 myelomonoblasts with deferoxamine, iron chelator, results in doubling of their “TF+AA” resistance. However, the use of iron-containing TF analogs leads to its doubled cytotoxicity. Conclusion. In leukemia cell line U937 with constitutively active НО-1/Ft the heme-dependent activation of it does not considerably contribute to protection of cells from “TF+AA” toxicity. The system “TF+AA” is НО-1 and Ft expression inducer in U937 myelomonoblasts. Cytotoxic mechanism of “TF+AA” involves intracellular pool of “labile” non-heme iron, the level of which affects the drug sensibility of leukemia cells.

5-Acetamido-1-(methoxybenzyl) isatin inhibits tumor cell proliferation, migration, and angiogenesis.

Indole and its derivatives are widely distributed in both animals and plants. Among its array of biological activities, the anti-tumor activity of indole has garnered much attention. Furthermore, the synthesis and activity of indole derivatives, including isatin, constitute a flourishing research topic. Previously, many isatin derivatives were synthesized by our group, and 5-acetamido-1-(methoxybenzyl) isatin was screened as a candidate anti-tumor agent. In this study, we found that 5-acetamido-1-(methoxybenzyl) isatin inhibited the proliferation of several tumor cell lines, especially the human leukemia cell line K562. Morphological observation suggested that 5-acetamido-1-(methoxybenzyl) isatin induced apoptosis and caused cell cycle arrest in K562 cells. Flow cytometry revealed that 5-acetamido-1-(methoxybenzyl) isatin induced mitochondrial pathway-mediated apoptosis in K562 cells. Moreover, it downregulated Cyclin B and CDC25C and upregulated p-CDC25C and p-CDK1 (Thr14), and induced K562 cell cycle arrest in the G2/M phase. Findings from wound healing as well as transwell assay determined that 5-acetamido-1-(methoxybenzyl) isatin could suppress migration and chemotaxis in HepG2 liver cancer cells. 5-Acetamido-1-(methoxybenzyl) isatin also inhibited angiogenesis of the human umbilical vein endothelial cell line HUVEC, determined via a cell tube formation study. A clone formation study indicated that 5-acetamido-1-(methoxybenzyl) isatin can inhibit tumor cell proliferation and population dependence in a concentration-dependent manner. Thus, our findings support that 5-acetamido-1-(methoxybenzyl) isatin could be used as a potential antitumor candidate in future investigations.

Design, synthesis and evaluation of biological activities of some novel anti-TB agents with bio-reducible functional group.

Introduction: With regard to the anti-mycobacterial activity of 2-pyrazinoic acid esters (POEs), recent studies have shown that both pyrazine core and alkyl part of POE interact with the fatty acid synthase type (I) (FAS (I)) precluding a complex formation between NADPH and FAS (I). Methods: Considering this interaction at the reductase site of FAS (I) responsible for reduction of β-ketoacyl-CoA to β-hydroxyacyl-CoA, we hypothesized that POE containing a bioreducible center in its alkyl part might show an increased anti-tubercular activity due to the involvement of FAS (I) in extra bio-reduction reaction. Thus, we synthesized novel POEs, confirmed their structures by spectral data, and subsequently evaluated their anti-mycobacterial activity against Mycobacterium tuberculosis (Mtb) (H37Rv) strain at 10 μg/mL concentration. Results: Compounds 3c, 3j, and 3m showed higher activity with regard to the inhibition of Mtb growth by 45.4, 45.7, and 51.2% respectively. Unexpectedly, the maltol derived POE 3l having the lowest log p value among the POEs indicated the highest anti-mycobacterial growth activity with 56% prevention. Compounds 3c and 3l showed no remarkable cytotoxicity on human macrophages at 10 μg/mL concentration as analyzed by xCELLigence real-time cell analysis. In further experiments, some of the tested POEs, unlike pyrazinamide (PZA), exhibited significant antibacterial and also anti-fungal activities. POEs showed an enhanced bactericidal activity on gram-positive bacteria as shown for Staphylococcus aureus , e.g. compound 3b with a MIC value of 125 μg/mL but not E. coli as a gram-negative bacteria, except for maltol derived POE (3l) that showed an inverse activity in the susceptibility test. In the anticancer activity test against the human leukemia K562 cell lines using MTT assay, compounds 3e and 3j showed the highest cytotoxic effect with IC50 values of 25±8.0 μΜ and 25±5.0 μΜ, respectively. Conclusion: It was found that the majority of POEs containing a bioreducible center showed higher inhibitory activities on Mtb growth when compared to the similar compounds without a bio-reducible functional group.

Changes in IDH2, TET2 and KDM2B Gene Expression After Treatment With Classic Chemotherapeutic Agents and Decitabine in Myelogenous Leukemia Cell Lines

BackgroundHematological malignancies are a heterogeneous group of tumors with increased proliferative and auto-replicative capacity. Despite treatment advances, post-treatment quality of life remains highly affected. Studies addressing the molecular mechanisms of these diseases are critical for the development of effective, rapid and selective therapies, since few therapeutic strategies succeed in being effective without triggering high-grade toxicities or debilitating late effects. Our aim of this study was to verify changes in the expression of genes involved in the malignant phenotype of hematological malignancies, by treating human cell lines in vitro with classic chemotherapeutic agents and the demethylating agent, decitabine.MethodsKASUMI-1 and K-562 human myeloid leukemia cell lines were plated at a density of 3 × 104 cells/well and treated with increasing concentrations of different chemotherapeutic agents commonly used in the clinical setting. After 24 and 48 h of treatment, cell viability was tested, and RNA was extracted. Complementary DNA (cDNA) was synthesized and quantitative real-time polymerase chain reaction (qPCR) was performed to evaluate the gene expression of IDH2, TET2 and KDM2B.ResultsA modulation in gene expression was observed before and after treatment with classic chemotherapeutic agents. It was possible to demonstrate a difference in gene expression when cells were treated with chemotherapeutic agents or decitabine alone when compared to chemotherapeutic agents in association with decitabine.ConclusionsThe genes tested, and the modulation of their expression during in vitro treatments suggest that IDH2, TET2, and KDM2B should be further investigated as potential biomarkers for ongoing treatment response and follow-up for patients diagnosed with hematological malignancies of the myeloid lineage.

TIGIT Expression Positively Associates with NK Cell Function in AML Patients

Natural killer (NK) cells are essential innate immune effectors with promising anti-leukemia activity in acute myeloid leukemia (AML). However, clinical success of applying NK cells in AML treatment has not been achieved. A better understanding of the regulatory mechanisms for NK cell function is important to optimize this therapeutic strategy. T cell immunoglobulin and ITIM domain (TIGIT) is a recently identified inhibitory receptor expressed on T cells and NK cells. Multiple studies including ours have demonstrated its suppressive effect in anti-tumor CD8 T cell response. However whether and how TIGIT impacts NK cells in AML is unknown. Here we performed phenotypic and functional studies on NK cells derived from patients with newly diagnosed AML (n=30). Cells collected from healthy individuals (n=18) were used as controls. TIGIT expression and their contributions to NK cell function in AML were assessed.Peripheral blood samples were first examined by flow cytometry for the frequency of NK cells (defined as CD56+CD3-). The percentage of NK cells among peripheral blood mononuclear cells (PBMCs) in AML patients is comparable with that of healthy controls. In contrast, when we performed functional analysis to assess NK cells for cytokine release upon in vitro stimulation with a human leukemia cell line K562, we observed significantly lower intracellular production of IFN-γ in cells from AML patients compared with that of healthy controls. Consistently NK cells from AML patients expressed less Perforin, indicating a compromised killing capacity. We next evaluated the expression of TIGIT on CD56+CD3- NK cells. As some AML blasts and monocytes also express CD56, we performed multichannel flow cytometry and carefully gated out other cell components when assessing TIGIT expression. To our surprise, we observed a significantly lower frequency of TIGIT-expressing NK cells in AML compared with that of healthy controls (36.82 ±4.543% vs. 48.9±3.818%, P=0.0463). This data indicated that low-TIGIT expression associates with impaired NK cell function and AML progression.We further examined the phenotype and functional status of TIGIT+ NK cells. Expression of activating receptors (CD16 and CD160) and inhibiting receptors (KIR and NKG2A) on TIGIT+ vs. TIGIT- NK cells were analyzed. We observed a significant higher expression of CD16 (51.27±9.009% vs. 20.63±5.334%, P=0.0001) and CD160 (39.84±6.447% vs. 21.24±4.287%, P=0.0103) on TIGIT+ NK cells compared with that of TIGIT- NK cells. By contrast, TIGIT+ NK cells expressed lower KIR (24.06±3.796% vs. 43.59±6.96%, P=0.0046) and NKG2A (7.658±1.717% vs. 18.68±4.256%, P=0.0167) than TIGIT- NK cells. Importantly, functional studies demonstrated an elevated expression of Granzyme B and increased cytokine (IFN-γ and TNF-α) production by TIGIT+ NK cells compared with TIGIT- NK cells (IFN-γ, P=0.0283; TNF-α P=0.0347; Granzyme B, P=0.0493). These data suggest that TIGIT expression on NK cells associated with activated and high functional status.Collectively, our study demonstrates that 1) in line with lower capacity to produce IFN-γ, NK cells from AML patients express less frequency of TIGIT compared with healthy individuals; 2) TIGIT+ NK cells from AML patients express high levels of activating receptors and are highly functional manifested by more cytokine production and enhanced expression of Granzyme B compared with TIGIT- NK cells. These results indicate that in AML patient, TIGIT may contribute to the upregulation of NK cell function. This is in contrast to the observations of CD8 T cells in which TIGIT plays a suppressive role. Targeting TIGIT for cancer treatment is currently under active development. Our findings bring a call for caution on the TIGIT-targeted therapeutic strategy in AML as TIGIT might be a double-edged sword in anti-leukemia immune regulation. DisclosuresNo relevant conflicts of interest to declare.

Two new tetralone glycosides from the green walnut husks of Juglans mandshurica Maxim

Two new tetralone glycosides, 4(S)-5-methoxy juglanoside A (1), 4(S)-5-methoxy juglanoside D (2), together with ten known compounds (3–12) have been isolated from the green walnut husks of Juglans mandshurica Maxim. Their structures were elucidated on the basis of their ESI-MS, 1 D and 2 D NMR spectroscopic data. In addition, all compounds were evaluated for their cytotoxic activities against the cancer BGC-823 (human gastric carcinoma), HCT-15 (human colorectal carcinoma) and K562 (human chronic myeloid leukemia) cell lines. The results showed aglycones of naphthoquinones had stronger cytotoxic activities than glycosides of tetralone.

Effects of telomerase inhibitor on epigenetic chromatin modification enzymes in malignancies.

Telomerase has a critical role in cell proliferation, tumor maintaining, and therapy resistance, which act by modifying many signaling pathways. 2-[(E)-3-Naphtalen-2-yl-but-2-enoylamino]-benzoic acid (BIBR1532) is one of the most studied telomerase inhibitors, and it targets telomerase components TERC and TERT. In this novel study, we aimed to investigate the epigenetic effects of BIBR1532 on both hematologic malignancies and solid tumors. K-562 human chronic myeloid leukemia cell line and U87MG glioblastoma cell line were compared with control groups without BIBR1532 treatment. Cytotoxic effects of BIBR1532 were determined by using WST-1 assay. Apoptotic effects of BIBR1532 were detected by using annexin V method. To assess expression changes in the human epigenetic chromatin modification enzyme genes, total RNA was isolated from K-562 and U87MG cells treated with BIBR1532 and untreated control cells. BIBR1532 induced 2.41-fold apoptotic cell death in U87MG cell lines compared with control groups. Apoptosis was slightly induced in K-562 cells with BIBR1532 treatment compared with control cells. We observed that BIBR1532 also regulates similar genes in both cell lines, and it is useful on epigenetic mechanisms. As a result, telomerase inhibitor BIBR1532 has a significant effect on both hematological malignancies and solid tumors.

A novel synthesized 3’, 5’-diprenylated chalcone mediates the proliferation of human leukemia cells by regulating apoptosis and autophagy pathways

Leukemia is a hematologic malignancy with poor prognosis in humans and chemotherapy is the main strategy for treating leukemia patients. Novel drugs with better selectivity and lower toxicity are required for the treatment of patients. A novel 3’,5’-diprenylated chalcone, (E)-1-(2-hydroxy-4-methoxy-3,5-diprenyl) phenyl-3-(3- pyridinyl)-propene-1-one (C10) is a potential new anti-leukemia agent. In this study, we investigated the molecular mechanisms of the anti-leukemia effects of C10 on different leukemia cells in vitro. C10 showed strong inhibition of proliferation of the human erythroleukemia cell line HEL and human myeloid leukemia cell line K562, and several cell and flow cytometer assays showed that inhibition by C10 was due to the regulation of gene expression or phosphorylation in the apoptosis and autophagy pathways. The results showed that C10 regulated the expression of Bax, c-Myc, Bcl-2, P38/AMPK and ERK 1/2, activated the expression of Caspase-3, -8, and PARP at the protein level in the apoptosis pathway of the two leukemia cell types, and inhibited the expression of erythroleukemia carcinogene Fli-1 in the human erythroleukemia cell line HEL. Additionally,treatment with the compound induced a time-dependent increase in expression of LC 3A/B via inhibiting the AKT-mTOR pathway, which is associated with cell autophagy. Taken together, the above results suggest that the novel synthesized 3’,5’-diprenylated chalcone can prevent the growth of leukemia cells by inducing apoptosis and autophagy.

TRPM7-mediated spontaneous Ca2+ entry regulates the proliferation and differentiation of human leukemia cell line K562.

Continuous Ca2+ influx is essential to maintain intracellular Ca2+ homeostasis and its dysregulation leads to a variety of cellular dysfunctions. In this study, we explored the functional roles of spontaneous Ca2+ influx for the proliferation and differentiation of a human erythromyeloid leukemia cell line K562. mRNA/protein expressions were assessed by the real‐time RT‐PCR, western blotting, and immunocytochemical staining. Intracellular Ca2+ concentration ([Ca2+]i) and ionic currents were measured by fluorescent imaging and patch clamping techniques, respectively. Cell counting/viability and colorimetric assays were applied to assess proliferation rate and hemoglobin synthesis, respectively. Elimination of extracellular Ca2+ decreased basal [Ca2+]i in proliferating K562 cells. Cation channel blockers such as SK&F96365, 2‐APB, Gd3+, and FTY720 dose dependently decreased basal [Ca2+]i. A spontaneously active inward current (I spont) contributive to basal [Ca2+]i was identified by the nystatin‐perforated whole‐cell recording. I spont permeated Ca2+ comparably to Na+, and was greatly eliminated by siRNA targeting TRPM7, a melastatin member of the transient receptor potential (TRP) superfamily. Consistent with these findings, TRPM7 immune reactivity was detected by western blotting, and immunofluorescence representing TRPM7 was found localized to the K562 cell membrane. Strikingly, all these procedures, that is, Ca2+ removal, TRPM7 blockers and siRNA‐mediated TRPM7 knockdown significantly retarded the growth and suppressed hemin‐induced γ‐globin and hemoglobin syntheses in K562 cells, respectively, both of which appeared associated with the inhibition of ERK activation. These results collectively suggest that spontaneous Ca2+ influx through constitutively active TRPM7 channels may critically regulate both proliferative and erythroid differentiation potentials of K562 cells.

A rapid and sensitive LC–MS/MS method for quantitative analysis of cardiolipin (18:2)4 in human leukocytes and mouse skeletal muscles

A rapid and sensitive LC–MS/MS method has been developed for quantitative analysis of cardiolipin (18:2)4 or CL (18:2)4 in human leukocytes and mouse mitochondria. The structural analog CL (14:0)4 was used as the internal standard. Both CL (18:2)4 and the IS were extracted using a modified Folch method, and separated on a Waters XBridge® BEH C18 XP column using a mobile phase of 0.1% ammonium hydroxide in acetonitrile/water (90:10, v/v) pumped at a flow rate of 0.4 mL/min. Quantitation was achieved by negative ESI-MS/MS in MRM mode. The total run time was 2.00 min with retention times of 0.74 min for the IS and 0.84 min for CL (18:2)4, respectively. The method was validated according to the US-FDA guidance for bioanalytical method validation using human leukemia and lymphoma cell lines, which had a calibration range of 0.120–60.2 nM with a correlation coefficient >0.999. The intra- and inter-assay accuracy and precision were ≤±5% and ≤8%. The IS normalized matrix factors of CL (18:2)4 and the IS normalized recoveries of CL (18:2)4 ranged 0.92–1.04, and 95–101%, respectively. The stability studies showed that CL (18:2)4 was stable under various test conditions. The developed method was successfully applied to the measurement of CL (18:2)4 in various biological samples including K562 and HL-60 human leukemia cell lines, U937 human lymphoma cell line, white blood cells from patients of Alzheimer’s disease and normal cognitive controls (NCCs), and mitochondria from mouse skeletal muscles. It may be useful for preclinical and clinical studies of this compound.

Effects of cultivated Cordyceps sinensis on proliferation and apoptosis of human leukemia K562 cells

The present study was designed to investigate the effect of cultivated Cordyceps sinensis (CCS) on leukemia-derived K562 cells, and further explore the underlying mechanisms. After routine culture of K562 cells, MTT assay was used to detect the effect of CCS on survivel of human leukemia cell lines K562;DAPI staining was used to observe the morphological changes of the nucleus and AO/EB staining was used to observe cell apoptosis. JC-1 staining was employed to detect the changes in mitochondrial membrane potential. Flow cytometry (FCM) was used to detect cell cycle distribution, and Western blot analysis was used to detect the expression levels of Bax, Bcl-2, caspase 3, caspase 8, cyclin D1, CDK2, and CDK4 in K562 cells. The results showed that CCS (0.345-5.524 g·L⁻¹) substantially suppressed proliferation of K562 cells and induced G₁/S phase arrest in a dose-dependent manner. DAPI and AO/EB staining indicated that cell apoptosis was significantly induced by CCS treatment, accompanied by decreased mitochondrial membrane potential demonstrated by JC-1 staining. Western blot results showed that CCS significantly increased the expression of Bax and, meanwhile, decreased the expression levels of Bcl-2, cyclin D1, CDK2, CDK4, caspase 3 and caspase 8. Collectively, our data demonstrated that CCS dose-dependently suppressed cell proliferation and induced cell apoptosis in K562 cells, and the mechanism might be associated with inducing cell cycle arrest, regulating Bcl-2/Bax ratio and activating the mitochondrial apoptosis pathway.

Costunolide promotes imatinib-induced apoptosis in chronic myeloid leukemia cells via the Bcr/Abl-Stat5 pathway.

Costunolide, a sesquiterpene lactone, is a small molecular monomer extracted from Inula helenium (Compositae). In the present study, we assessed the antileukemia effects of costunolide on the human chronic myeloid leukemia cell line K562 and its combined activity with imatinib. A Cell Counting Kit-8 assay demonstrated that costunolide significantly inhibited K562 cell proliferation and enhanced imatinib-induced anti-proliferative activity. We found that costunolide significantly induced mitochondrial apoptosis in K562 cells by modulating the protein levels of Bcl-2 family members and by inducing caspase activation. Costunolide promoted imatinib-induced apoptosis via the Bcr/Abl-signal transducer and activator of transcription 5 pathway. Costunolide inhibited proliferation by inducing cell cycle arrest in the G2 /M phase by decreasing cyclin B1 and cyclin-dependent kinase 2 expression and increasing p21 expression. Together, these results demonstrate that costunolide may be a potent therapeutic agent against chronic myeloid leukemia.

Co-addition Strategy for Enhancement of Chaetominine from Submerged Fermentation of Aspergillus fumigatus CY018.

Chaetominine (CHA), a novel framework tripeptide alkaloid, imparts an attractive cytotoxic against the human leukemia cell line K562, which is produced by Aspergillus fumigatus CY018. However, its pharmacological research is restricted by low yields in submerged culture, which needs to be resolved immediately by biotechnology. In this work, a co-addition strategy was applied to promote CHA production based on related inhibitors' addition and precursors' addition, inspired by the biosynthetic pathway analysis of CHA. CHA production reached 53.87mg/L by addition of 10mM shikimate, 10mM anthranilate, 20mM tryptophan, and 10mM alanine in shake flask. Compared to the control without addition of precursors, the activity of 3-deoxy-arabino-heptulosonate-7-phospahte (DAHP) synthase was significantly improved and the transcription levels of critical genes in shikimate pathway were up-regulated responded to the co-addition of precursors. The improvement of CHA production by co-addition of precursors was also successfully reproduced in the lab-scale bioreactor (5-L) system, in which CHA production reached 46.10mg/L. This work demonstrated that precursors' co-addition was an effective strategy for increasing CHA production, and the information obtained might be useful to the further improvement of CHA on a large scale.

Long noncoding RNA UCA1 promotes cell proliferation, migration and invasion of human leukemia cells via sponging miR-126.

Acute myeloid leukemia (AML) is a bone marrow malignancy. Long non-coding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) plays an important role in several cancers. However, the role of lncRNA UCA1 in AML remained unclear. LncRNA UCA1 expressions in different cell lines were determined by RT-PCR. In human myelogenous leukemia (ML) cell lines K562 and HL60, effects of lncRNA UCA1 knockdown on cell viability, migration, invasion, and apoptosis were assessed, respectively. Binding effects between lncRNA UCA1 and microRNA (miR)-126, and between miR-126 and RAC1 3'UTR were detected by RT-PCR and luciferase activity assay. Involvements of miR-126 and RAC1 in lncRNA UCA1-mediated cell bioactivities were assessed. We found that lncRNA UCA1 was upregulated in ML cell lines. Knockdown of lncRNA UCA1 inhibited cell viability, migration, invasion, and prompted apoptosis of ML cells in vitro. LncRNA UCA1 could bind with miR-126 and downregulate miR-126 expression. Simultaneously, the anti-growth and anti-metastasis actions of lncRNA UCA1 knockdown on ML cells were reversed by miR-126 suppression. RAC1 was a target gene of miR-126, and the anti-ML actions of miR-126 were abolished by RAC1 overexpression. Moreover, PI3K/AKT and JAK/STAT signaling pathways were blocked by miR-126 overexpression while were activated by RAC1 overexpression. Taken together, this study elucidates a novel UCA1-miR-126-RAC1 regulatory network in ML cells, which may provide the feasibility for use lncRNA-based therapy in AML treatment.