Evaluation of Silencing Effect of miR-133a-5p Mimic on TIM-3 Expression in AML (HL-60) Cell Line

Acute myelogenous leukemia (AML) is a complex blood malignancy leading to immature leukemic stem cells (LSCs) proliferation. T cell immunoglobulin mucin-3 (TIM-3) is known as a biomarker of AML LSCs. Several microRNAs (miRNAs) can affect gene expression in AML. In this study, the silencing effect of miR-133a-5p on TIM-3 expression in AML cell lineage (HL-60) was investigated. It's been hypothesized that miR-133a-5p may suppress the TIM-3 expression in AML cell line. Initially, miRNA-TIM-3 prediction, enrichment, and network analysis were done. Then, miR-133a-5p mimic was transfected into HL-60 cells. The TIM-3 protein and gene expression were measured by flow cytometry analysis and real-time PCR, respectively. MTT assay was also carried out. Based on the Bioinformatics predictions, miR-133a-5p was able to silence TIM-3 expression. Also, significant pathways pertained to miR-133a-5p were obtained using enrichment analysis. According to this, miR-133a-5p was mainly engaged in the MAPK signaling pathway and Nicotine addiction pathway using the KEGG database. The TIM-3 protein expression of the transfected cells was measured as 17.15 ± 8.87% (p = 0.001). A 52.48% significant gene silencing in mRNA level was obtained in comparison to the negative control. Despite of down regulation of TIM-3, HL-60 cell viability has not been significantly changed. It has been finally confirmed that miR-133a-5p could strongly suppress TIM-3 expression in AML cell line. Presumably, down regulation of TIM-3 could affect MAPK and Nicotine addiction signaling pathways.

In vitro investigating of anticancer activity of new 7-MEOTA-tacrine heterodimers

A combination of biochemical, biophysical and biological techniques was used to study calf thymus DNA interaction with newly synthesized 7-MEOTA-tacrine thiourea 12-17 and urea heterodimers 18-22, and to measure interference with type I and II topoisomerases. Their biological profile was also inspected in vitro on the HL-60 cell line using different flow cytometric techniques (cell cycle distribution, detection of mitochondrial membrane potential dissipation, and analysis of metabolic activity/viability). The compounds exhibited a profound inhibitory effect on topoisomerase activity (e.g. compound 22 inhibited type I topoisomerase at 1 µM concentration). The treatment of HL-60 cells with the studied compounds showed inhibition of cell growth especially with hybrids containing thiourea (14-17) and urea moieties (21 and 22). Moreover, treatment of human dermal fibroblasts with the studied compounds did not indicate significant cytotoxicity. The observed results suggest beneficial selectivity of the heterodimers as potential drugs to target cancer cells.

The Effect of Manuka Honey on dHL-60 Cytokine, Chemokine, and Matrix-Degrading Enzyme Release under Inflammatory Conditions

A large body of in vivo and in vitro evidence indicates that Manuka honey resolves inflammation and promotes healing when applied topically to a wound. In this study, the effect of two different concentrations (0.5% and 3% v/v) of Manuka honey on the release of cytokines, chemokines, and matrix-degrading enzymes from neutrophils was examined using a differentiated HL-60 cell line model in the presence of inflammatory stimuli. The results indicate that 0.5% honey decreased TNF-α, IL-1β, MIP-1α, MIP-1β, IL-12 p70, MMP-9, MMP-1, FGF-13, IL-1ra, and IL-4 release, but increased MIP-3α, Proteinase 3, VEGF, and IL-8 levels. In contrast, 3% honey reduced the release of all analytes except TNF-α, whose release was increased. Together, these results demonstrate a dose-dependent ability of Manuka honey to modify the release of cytokines, chemokines, and matrix-degrading enzymes that promote or inhibit inflammation and/or healing within a wound. The findings of this study provide further guidance for the future use of Manuka honey in wounds or tissue engineering templates. Future in vivo investigation is warranted to validate the in vitro results and translate these results to physiologically relevant environments.

In vitro and in vivo anti-leukemia activity of the stem bark of Salacia impressifolia (Miers) A. C. Smith (Celastraceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Salacia impressifolia (Miers) A. C. Smith (family Celastraceae) is a traditional medicinal plant found in the Amazon Rainforest known as "miraruíra", "cipó-miraruíra" or "panu" and is traditionally used to treat dengue, flu, inflammation, pain, diabetes, male impotency, renal affections, rheumatism and cancer.

AIM OF THE STUDY

The aim of this study was to investigate in vitro and in vivo anti-leukemia activity of the stem bark of S. impressifolia in experimental models.

MATERIALS AND METHODS

The in vitro cytotoxic activity of extracts, fractions and quinonemethide triterpenes (22-hydroxytingenone, tingenone and pristimerin) from the stem bark of S. impressifolia in cultured cancer cells was determined. The in vivo antitumor activity of the ethyl acetate extract (EAE) and of its fraction (FEAE.3) from the stem bark of S. impressifolia was assessed in C.B-17 severe combined immunodeficient (SCID) mice engrafted with human promyelocytic leukemia HL-60 cells.

RESULTS

The extract EAE, its fraction FEAE.3, and quinonemethide triterpenes exhibited potent cytotoxicity against cancer cell lines, including in vitro anti-leukemia activity against HL-60 and K-562 cells. Moreover, extract EAE and its fraction FEAE.3 inhibited the in vivo development of HL-60 cells engrafted in C.B-17 SCID mice. Tumor mass inhibition rates were measured as 40.4% and 81.5% for the extract EAE (20 mg/kg) and for its fraction FEAE.3 (20 mg/kg), respectively.

CONCLUSIONS

Ethyl acetate extract and its fraction from the stem bark of S. impressifolia exhibit in vitro and in vivo anti-leukemia activity that can be attributed to their quinonemethide triterpenes. These data confirm the ethnopharmacological use of this species and may contribute to the development of a novel anticancer herbal medicine.

An optimized permeabilization step for flow cytometry analysis of nuclear proteins in myeloid differentiation of blood cells into neutrophils

Polymorphonuclear leukocytes (PMNLs) or neutrophils play an important role in the innate immune response. Working with human neutrophils is challenging because these cells are sensitive to changes in the surrounding media and quickly become apoptotic. Meanwhile the experiments with mature neutrophils may be very important for studies of blood function. In this paper we propose an improved technique of flow cytometry nuclear protein analysis with double antibody labeling, which allows direct comparison of protein quantity (overlay histograms) in the primary cells (neutrophils) and progenitor cell lines (line HL-60), to study differentiation process and for other research purposes. We suggest improved technique to analyze and compare nuclear proteins levels in the myeloid differentiation model system (HL-60 cell line) and / or primary human neutrophils. This method was justified with measurement of GFI1 protein expression level, as well-known transcription factor, typical and essential for mature neutrophils. The key protocol features are as follows: •Suggested protocol allows simply, direct and correct visual comparison of flow cytometry data in overlay diagrams for myeloid blood cells on various stages of differentiation.•70% ethanol permeabilization of neutrophils and HL-60 cells results in lower background fluorescence and better peak resolution than MeOH and Saponin permeabilization.•Non-specific antibody binding in neutrophils can be efficiently blocked by using 1% BSA and non-immune goat serum.

Retinoic acid and 6-formylindolo(3,2-b)carbazole (FICZ) combination therapy reveals putative targets for enhancing response in non-APL AML

In non-acute promyelotic leukemia (APL)- non myelocytic leukemia (AML), identification of a signaling signature would predict potentially actionable targets to enhance differentiation effects of all-trans-retinoic acid (RA) and make combination differentiation therapy realizable. Components of such a signaling machine/signalsome found to drive RA-induced differentiation discerned in a FAB M2 cell line/model (HL-60) were further characterized and then compared against AML patient expression profiles. FICZ, known to enhance RA-induced differentiation, was used to experimentally augment signaling for analysis. FRET revealed novel signalsome protein associations: CD38 with pS376SLP76 and caveolin-1 with CD38 and AhR. The signaling molecules driving differentiation in HL-60 cluster in non-APL AML de novo samples, too. Pearson correlation coefficients for this molecular ensemble are nearer 1 in the FAB M2 subtype than in non-APL AML. SLP76 correlation to RXRα and p47phox were conserved in FAB M2 model and patient subtype but not in general non-APL AML. The signalsome ergo identifies potential actionable targets in AML.

Differentiation of neutrophil-like HL-60 cells strongly impacts their rolling on surfaces with various adhesive properties under a pressing force

BACKGROUND

HL-60 cells have been used in in vitro experiments of neutrophils rolling. They lose uniform spherical appearance and enhance deformability by differentiation to neutrophil-like cells, which would affect their rolling characteristics.

OBJECTIVE

We investigate the influence of differentiation and coating of target substrate on the fundamental rolling characteristics of the cells under a constant pressing force which mimics the pressing force to the vessel wall by erythrocytes in vivo.

METHODS

Motions of undifferentiated and differentiated HL-60 cells on plain or MPC-polymer-coated flat glass substrate were compared using a homemade inclined centrifuge microscope system.

RESULTS

Most of the cells alternated between stop and go during the motion. The differentiation resulted in a high temporal ratio of the non-moving state and low mean velocity during the moving state, together with a high suppression performance of cell adhesion by the polymer. It was also suggested that the cells were mostly rolling but that the coating probably induced an infrequent slip on the substrate to stabilize the cells motion.

CONCLUSIONS

Differentiation strongly affects adhesivity of HL-60 cells but less affects the mean velocity. Our findings also demonstrate the importance of the pressing force and advantage of the present system with respect to classical flow chambers.

Enhanced cytotoxic effects of arsenite in combination with anthocyanidin compound, delphinidin, against a human leukemia cell line, HL-60

Among five major anthocyanin compounds, delphinidin exhibited the most potent and selective cytocidal effect against HL-60, a trivalent arsenic (As(III))-resistant cell line. Co-treatment with delphinidin and As(III) resulted in the reduction of IC₅₀ value for As(III) from 11.2 to 1.5 μM, which was considered as clinically achieved concentrations of As(III). The combination treatment strongly preferred to selectively enhance the cytotoxicity of As(III) against HL-60 cells rather than human peripheral blood mononuclear cells. The induction of apoptosis as evidenced by the increase of sub-G₁ cells, DNA fragmentation, annexin V-positive cells and the activation of caspase-8, -9 and -3 was observed in HL-60 cells co-treated with As(III) and delphinidin. Similar to the activation pattern of caspases, a substantial decrease in the expression level of Bid along with the loss of mitochondrial membrane potential was also observed. These results suggested that the combination treatment triggered a convergence of the intrinsic and extrinsic pathways of apoptosis via the activation of caspase-8 and cleaved Bid. Delphinidin itself significantly decreased the intracellular GSH ([i]GSH) and nuclear factor-κB (NF-κB) binding activity, and further returned As(III)-triggered increment of [i]GSH and enhancement of NF-κB binding activity to control level. Additionally, buthionine sulfoximine, a GSH depletor; JSH-23, a NF-κB inhibitor, also mimicked the capacity of delphinidin to significantly induce the reduction of [i]GSH along with the potentiation of As(III) cytotoxicity in HL-60 cells. These observations suggested that delphinidin-induced sensitization of HL-60 cells to As(III) was caused by the reduction of [i]GSH, which was probably associated with the inhibitory effect of delphinidin on NF-κB binding activity. These findings further suggest that delphinidin-induced sensitization of HL-60 cells to As(III) may lead to dose reduction of As(III) in clinical application, and ultimately contribute to minimizing its side effects.

Evaluation of the effect of TIM-3 suppression by miR-498 and its effect on apoptosis and proliferation rate of HL-60 cell line

BACKGROUND

Acute Myeloid Leukemia (AML) is a Cancer of hematopoietic stem cells with a rapid progression. TIM-3 is expressed on leukemic stem cells (LSCs) in most types of AML and might have a positive effect on maintenance of malignant phenotype. MicroRNAs play important roles in either cancer progression or suppression. In this study were evaluated, the inhibitory effect of miR-498 on TIM-3 expression and its impact on proliferation and survival of HL-60 cell line.

METHODS

Firstly, the probable inhibitory effect of miR-498 on TIM-3 expression was predicted. HL-60 cells were cultured and expression of TIM-3 was induced on the cells using phorbol miristate acetate. The cells were transfected with miR-498 and expression level of TIM-3 were measured using with q-RT-PCR and flow cytometry methods. In addition, the effect of suppression of TIM-3 expression in HL-60 cell line was analyzed with apoptosis and cell proliferation assays.

RESULTS

Bioinformatics analyses predicted that miR-498 has high ability to silence TIM-3 gene expression. Our experiments confirmed that miR-498 was able to strongly silence TIM-3 expression (68% silencing) in HL-60 cell line (P < 0.002). Also, the cells with suppressed expression of TIM-3 had a lower proliferation and higher apoptosis rates.

CONCLUSION

Based on our results, the miR-498 can effectively suppress TIM-3 expression in the AML cell line. TIM-3 suppression, in turn, inhibits malignant cell proliferation and induces its apoptosis. Collectively, suppression of TIM-3 by miR-498 can be considered as a potential powerful way for treatment of AML.

Design and synthesis of new antitumor agents with the 1,7-epoxycyclononane framework. Study of their anticancer action mechanism by a model compound

This article describes the design, synthesis and biological evaluation of a new family of antitumor agents having the 1,7-epoxycyclononane framework. We have developed a versatile synthetic methodology that allows the preparation of a chemical library with structural diversity and in good yield. The synthetic methodology has been scaled up to the multigram level and can be developed in an enantioselective fashion. The study in vitro of a model compound, in front of the cancer cell lines HL-60 and MCF-7, showed a growth inhibitory effect better than that of cisplatin. The observation of cancer cells by fluorescence microscopy showed the presence of apoptotic bodies and a degradation of microtubules. The study of cell cycle and mechanism of death of cancer cells by flow cytometry indicates that the cell cycle arrested at the G₀/G₁ phase and that the cells died by apoptosis preferably over necrosis. A high percentage of apoptotic cells at the subG₀/G₁ level was observed. This indicates that our model compound does not behave as an antimitotic agent like nocodazole, used as a reference, which arrests the cell cycle at G₂/M phase. The interaction of anticancer agents with DNA molecules was evaluated by atomic force microscopy, circular dichroism and electrophoresis on agarose gel. The results indicate that the model compound has not DNA as a target molecule. The in silico study of the model compound showed a potential good oral bioavailability.

[Comparative proteomic profiling of nuclear and cytosolic fractions from cell lines of different origin]

Proteomic analysis of the nuclear fraction is of great importance, since many cellular processes are initiated in the nucleus. Refinement and choice of experimental procedures for cell lysate fractionation and parameters for mass spectrometric detection and data processing continue to be of current interest. The mass spectrometry analysis presented here was tested on human cell lines derived from different tissues: HL-60 (peripheral blood); HepG2 (liver); EA.hy926 (vascular endothelium). High reproducibility of results and their consistency with biological properties of the objects under study were demonstrated. The use of cells of different types made it possible to reveal a set of 16 proteins whose LFQ-values allow for the discrimination between proteome fractions regardless of cell origin. Also, a set of 16 proteins is suggested which are associated with individual characteristics of cell lines regardless of cell fraction. These protein panels can serve as parameters to verify the proteomic analysis done was of sufficient quality, in particular as indicators of successful fractionation of cell or tissue lysate.

Ru(II)-Thymine Complex Causes Cell Growth Inhibition and Induction of Caspase-Mediated Apoptosis in Human Promyelocytic Leukemia HL-60 Cells

Ruthenium-based compounds represent a class of potential antineoplastic drugs. Recently, we designed, synthesized, and identified the Ru(II)-thymine complex [Ru(PPh₃)₂(Thy)(bipy)]PF₆ (where PPh = triphenylphosphine, Thy = thymine and bipy = 2,2′-bipyridine) as a potent cytotoxic agent with the ability to bind to DNA and human and bovine serum albumins. In this study, the underlying cytotoxic mechanism of the [Ru(PPh₃)₂(Thy)(bipy)]PF₆ complex was assessed. This complex displayed potent cytotoxicity in different cancer cell lines; the morphology that is associated with apoptotic cell death, increased internucleosomal DNA fragmentation without cell membrane permeability, loss of the mitochondrial transmembrane potential, increased phosphatidylserine externalization, and caspase-3 activation were observed in human promyelocytic leukemia HL-60 cells that were treated with the complex. Moreover, pretreatment of HL-60 cells with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, partially reduced the apoptosis that was induced by the complex, indicating that the apoptotic cell death occurred through a caspase-mediated pathway. In conclusion, the [Ru(PPh₃)₂(Thy)(bipy)]PF₆ complex displays potent cytotoxicity to different cancer cells and induces caspase-mediated apoptosis in HL-60 cells.

Resveratrol induces autophagy-dependent apoptosis in HL-60 cells

BACKGROUND

All known mechanisms of apoptosis induced by resveratrol act through cell cycle arrest and changes in mitochondrial membrane potential. It is currently unknown whether resveratrol-induced apoptosis is associated with other physiological processes, such as autophagy.

METHODS

Apoptosis-related markers involved in the intrinsic and extrinsic apoptotic pathways, and autophagic markers were detected by using western blotting and immunofluorescence. Mitochondrial membrane potential was assayed by flow cytometry. Pharmaceutical or genetic inhibition of autophagy involved were carried by 3- methyladenine or knockdown of autophagy-related (Atg) genes by siRNA. Differences between two values were tested by Student's unpaired t test.

RESULTS

We show that resveratrol-induced apoptosis occurs through both the intrinsic and extrinsic apoptotic pathways. Mitochondrial membrane potential and apoptosis-related markers, such as an increased Bax/Bcl-2 ratio, and cleaved forms of caspase-8 and caspase-3, arise following resveratrol addition. Moreover, we find that resveratrol increases both the levels of microtubule-associated protein 1 light chain 3-II and the number of autophagosomes, and further demonstrate that resveratrol-induced autophagy depends on the LKB1-AMPK-mTOR pathway. We next reveal that some apoptosis-related markers induced by resveratrol are further attenuated by the inhibition of autophagy with 3-methyladenine or knockdown of autophagy-related (Atg) genes by siRNA.

CONCLUSIONS

These results suggest that resveratrol induced apoptotic cell death of HL-60 cells depends on the autophagy activated through both the LKB1-AMPK and PI3K/AKT-regulated mTOR signaling pathways.

Neutrophils mediate HIV-specific antibody-dependent phagocytosis and ADCC

There is growing evidence to support the role of Fc-mediated effector functions, such as Antibody-Dependent Cellular cytotoxicity (ADCC) and Antibody-Dependent Phagocytosis (ADP) in the protection and control of HIV. The RV144 trial and other recent HIV vaccine studies have highlighted the importance of ADCC responses in protection against HIV. The role of neutrophils, the most abundant leukocyte in the blood, has not been thoroughly evaluated for Fc-mediated effector functions to HIV. We optimized HIV-specific neutrophil ADCC and Antibody-Dependent Neutrophil Phagocytosis (ADNP) assays using freshly isolated primary human neutrophils from blood. We also developed methods to study ADP using the neutrophil-like HL-60 cell line. We found that neutrophils mediate both HIV-specific ADP and ADCC responses. In vitro, neutrophil-mediated ADCC responses peaked at 4 h, much faster than primary NK cell or monocyte-mediated responses. We detected a wide range of responses in the ADNP, HL-60 mediated ADP and ADCC across a cohort of 41 viremic antiretroviral therapy naïve HIV positive subjects. HL-60 and Neutrophil-mediated ADP and ADCC responses correlated well with each other, suggesting that they measure overlapping functions. The ADNP and HL-60 ADP inversely correlated with HIV viral load, suggesting that these antibody-mediated neutrophil-based assays should prove useful in dissecting HIV-specific immunity.

Cell Density-Dependent Cytological Stage Profile and Its Application for a Screen of Cytostatic Agents Active Toward Leukemic Stem Cells

Proliferation and expansion of leukemia is driven by leukemic stem cells (LSCs). Multidrug resistance (MDR) of LSCs is one of the main reasons of failure and relapses in acute myeloid leukemia (AML) treatment. In this study, we show that maintaining HL-60 at low cell culture density or applying a 240-day treatment with anthrapyridazone (BS-121) increased the percentage of primitive cells, which include LSCs determining the overall stage profile. This change manifested in morphology, expression of both cell surface markers and redox-state proteins, as well as mitochondrial potential. Moreover, four sublines were generated, each with unique and characteristic stage profile and cytostatic sensitivity. Cell density-induced culture alterations (affecting stage profiles) were exploited in a screen of anthrapyridazones. Among the compound tested, C-123 was the most potent against primitive cell stages while generating relatively low amounts of reactive oxygen species (ROS). Furthermore, it had low toxicity in vivo and weakly affected blood morphology of healthy mice. The cell density-dependent stage profiles could be utilized in preliminary drug screens for activity against LSCs or in construction of patient-specific platforms to find drugs effective in case of AML relapse (drug extrapolation). The correlation between ROS generation in differentiated cells and toxic effect observed in HL-60 has a potential application in myelotoxicity predictions. The discovered properties of C-123 indicate its potential application in AML treatment, specifically in conditioned myeloablation preceding allogeneic transplantation and/or ex vivo treatment preceding autologous transplantation.

Benzoquinone induces ROS-dependent mitochondria-mediated apoptosis in HL-60 cells

Benzene exposure affects the hematopoietic system and leads to the occurrence of various types of leukemia and hematotoxicity. It has been confirmed that active metabolites of benzene, including 1,4-benzoquinone (1,4-BQ), can induce reactive oxygen species (ROS) and apoptosis in the bone marrow, and recent studies have also suggested that benzene exposure can affect mitochondrial function in both experimental animals and cell lines. However, the potential relationship among ROS production, mitochondrial damages, and subsequent apoptosis following benzene exposure has not been well studied in detail. In the present study, we utilized HL-60 cells, a well-characterized human myeloid cell line, as an in vitro model and examined the effects of 1,4-BQ on intracellular ROS formation, mitochondria damage, and the occurrence of apoptotic events with or without using the ROS scavenger N-acetyl-l-cysteine (NAC). The results demonstrated that 1,4-BQ could dose-dependently induce production of ROS and mitochondrial damage as characterized by mitochondrial membrane potential disruption, mitochondrial ultrastructure alteration, and induced apoptosis and activated caspase-3 and caspase-9. Preincubation of HL-60 cells with NAC prior to 1,4-BQ treatment could block 1,4-BQ-induced production of ROS and the occurrence of apoptosis. These results demonstrated that 1,4-BQ induced apoptosis in HL-60 cells through a ROS-dependent mitochondrial-mediated pathway.

Curcumin differentially affects cell cycle and cell death in acute and chronic myeloid leukemia cells

Curcumin is a phytochemical with potent anti-neoplastic properties. The antitumoral effects of curcumin in cells derived from chronic or acute myeloid leukemia have been already described. However, a comparative study of the cytostatic and cytotoxic effects of curcumin on chronic and acute myeloid leukemia cells has not yet been performed. In the present study, the cellular effects of curcumin on cell lines derived from chronic or acute myeloid leukemia were examined. Dose and time-response assays were performed with curcumin on HL-60 and K562 cells. Cell viability was evaluated with trypan blue exclusion test and cell death by flow cytometry using a fluorescent molecular probe. A cell cycle profile was analyzed, and protein markers of cell cycle progression and cell death were investigated. In the present study, the K562 cells showed a higher sensitivity to the cytostatic and cytotoxic effects of curcumin compared with HL-60. In addition, curcumin induced G1 phase arrest in HL-60 cells and G2/M phase arrest in K562 cells. Furthermore, curcumin-related cell death in HL-60 was associated with the processed forms of caspases-9 and -3 proteins, whereas in K562 cells, both the processed and the unprocessed forms were present. Accordingly, activity of these caspases was significantly higher in HL-60 cells compared with that in K562. In conclusion, curcumin elicits different cellular mechanisms in chronic or acute myeloid leukemia cells and the powerful antitumoral effect was more potent in K562 compared with HL-60 cells.

The c-Raf modulator RRD-251 enhances nuclear c-Raf/GSK-3/VDR axis signaling and augments 1,25-dihydroxyvitamin D3-induced differentiation of HL-60 myeloblastic leukemia cells

Differentiation therapy is used in cancer treatment. Epidemiologic studies showed that higher vitamin D levels are associated with reduced cancer risks. However, the therapeutic doses needed for differentiation are accompanied by hypercalcemia and intolerable pathological sequelae. In the present work we evaluated if RRD-251, a small-molecule, can enhance vitamin D3-induced differentiation of leukemic cells, in the hope of decreasing the needed vitamin D3-dose.

We demonstrate that RRD-251 enhances vitamin D3-induced differentiation of leukemic cells, the enrichment of the c-Raf kinase in the nucleus, the binding of nuclear c-Raf to GSK-3, increased phosphorylation of GSK-3 ser 21/9 inhibitory sites, and the binding of GSK-3 to VDR, where GSK-3 inhibition is known to enhance transcriptional activation by VDR. Enhancement of D3-induced p-GSK-3 ser 21/9 by RRD-251 was associated with enhanced Akt-GSK-3 binding, Akt being a known GSK-3 inhibitor, and diminished Erk1/2 binding. Diminishing Erk interaction with GSK-3 was associated with enhanced interaction with Vav1, a known driver of myeloid differentiation. This is redolent of an ATRA/c-Raf/GSK-3/RARα axis we previously reported, although the phosphorylation effects to enhance transcriptional activation on RARα vs VDR diverge. Taken together this indicates potential therapeutic significance for a c-Raf/GSK-3/VDR or RARα axis for leukemic myelo-monocytic differentiation.

Steroidal Glycosides from Convallaria majalis Whole Plants and Their Cytotoxic Activity

Phytochemical examination of Convallaria majalis (Liliaceae) whole plants yielded 15 steroidal glycosides (1–15), including nine new compounds (4–6, 10–15) with a lycotetrose unit. The structures of the new compounds were determined using two-dimensional Nuclear magnetic resonance (NMR) analyses and chemical methods. The isolated compounds were evaluated for cytotoxicity against HL-60 human promyelocytic leukemia cells, A549 human lung adenocarcinoma cells, and HSC-4 and HSC-2 human oral squamous cell carcinoma cell lines. Of these, (25S)-spirost-5-en-3β-yl O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-β-d-galactopyranoside (1) exhibited cytotoxic activity against HL-60, A549, HSC-4, and HSC-2 cells with IC₅₀ values ranging from 0.96 to 3.15 μM. The corresponding furostanol glycoside of 1, (25S)-26-[(β-d-glucopyranosyl)oxy]-22α-hydroxyfurost-5-en-3β-yl O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-β-d-galactopyranoside (8), was cytotoxic to the adherent cell lines of A549, HSC-4, and HSC-2 cells with IC₅₀ values of 2.97, 11.04, and 8.25 μM, respectively. The spirostanol lycotetroside (1) caused necrotic cell death in A549 cells in a dose-dependent manner. Alternatively, the furostanol lycotetroside (8) induced apoptotic cell death in A549 cells in a time-dependent manner, as was evident by morphological observations and flow cytometry analyses.

Cytotoxic lanostane triterpenoids from the fruiting bodies of Piptoporus betulinus

Chemical investigation of a bioactive methanolic extract of the fruiting bodies of Piptoporus betulinus led to the isolation of five previously undescribed lanostane triterpenoids named piptolinic acids A-E, as well as five known lanostane triterpenoids. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic and HRESIMS analysis. Piptolinic acid A with an unusual moiety (3-hydroxy-4-methoxycarbonyl-3-methylbutyryloxy) at C-3 exhibited comparable cytotoxic activity against human promyelocytic leukemia cell line HL-60 (IC₅₀ = 1.77 μM) and human acute monocytic leukemia cell line THP-1 (IC₅₀ = 8.21 μM) to those of positive control, fluorouracil (IC₅₀ = 6.38 and 4.41 μM, respectively).

Photodynamically-induced Apoptosis Due to Ultraviolet A in the Presence of Lomefloxacin in Human Promyelocytic Leukemia Cells

Lomefloxacin (LFX) is a widely used fluoroquinolone antimicrobial agent that plays an important role in the treatment of human and animal infections; however, it has been reported to cause phototoxicity. In this study, we investigated the induction of apoptosis due to ultraviolet A (UVA) light in the presence and absence of LFX in HL-60 human promyelocytic leukemia cells. HL-60 cells were exposed to UVA at an intensity of 1.1 mW/cm² for 20 min in the presence and absence of LFX, and the induction of apoptosis was examined by analyzing cell morphology, DNA fragmentation, and caspase-3 activity. Cells treated with 100 μM LFX and UVA clearly showed membrane blebbing and cell shrinkage. The proportion of apoptotic cells was significantly higher in cells treated with both UVA and LFX than in those treated with UVA or LFX alone. In addition, DNA ladder formation and caspase-3 activation were observed in cells treated with both UVA and LFX. A significant reduction in the number of UVA-induced apoptotic cells and caspase-3 activation was observed when histidine was present, which suggested that photodynamically-generated singlet oxygen is an important mediator of apoptosis. These results indicate that the combination of UVA and LFX induces apoptosis in HL-60 cells.

Inhibition of Ser/Thr phosphatase PPM1D induces neutrophil differentiation in HL-60 cells

Protein phosphatase Magnesium-dependent 1, Delta (PPM1D) is a wild-type p53-inducible Ser/Thr phosphatase that acts as a negative regulator of the p53 tumor suppressor. Gene amplification and overexpression of PPM1D have been reported in various cancers including leukemia and neuroblastoma. Therefore, PPM1D is a promising target in cancer therapy. It has been reported that PPM1D knockout mice exhibit neutrophilia in blood and show a defective immune response. Here, we found that inhibition of PPM1D induced neutrophil differentiation of human promyelocytic leukemia cell line HL-60. The combination of a PPM1D inhibitor and all-trans retinoic acid significantly increased their differentiation efficiency. The PPM1D inhibitor also induced G1 arrest in HL-60 cells. Our results suggest that PPM1D may be a potential therapeutic target for blood cell diseases including leukemia.

Posaconazole-Loaded Leukocytes as a Novel Treatment Strategy Targeting Invasive Pulmonary Aspergillosis

Background

Impaired delivery of antifungals to hyphae within necrotic lesions is thought to contribute to therapeutic failure in invasive pulmonary aspergillosis (IPA). We hypothesized that transfusion of leukocytes loaded ex vivo with the lipophilic antifungal posaconazole could improve delivery of antifungals to the sites of established infection and improve outcome in experimental IPA.

Methods

The HL-60 leukemia cell line was differentiated to a neutrophil-like phenotype (differentiated HL-60 [dHL-60] cells) and then exposed to a range of posaconazole concentrations. The functional capacity and antifungal activity of these cells were assessed in vitro and in a mouse model of IPA.

Results

Posaconazole levels in dHL-60 cells were 265-fold greater than the exposure concentration. Posaconazole-loaded cells were viable and maintained their capacity to undergo active chemotaxis. Contact-dependent transfer of posaconazole from dHL-60 cells to hyphae was observed in vitro, resulting in decreased fungal viability. In a neutropenic mouse model of IPA, treatment with posaconazole-loaded dHL-60 cells resulted in significantly reduced fungal burden in comparison to treatment with dHL-60 cells alone.

Conclusions

Posaconazole accumulates at high concentrations in dHL-60 cells and increases their antifungal activity in vitro and in vivo. These findings suggest that posaconazole-loading of leukocytes may hold promise for the therapy of IPA.

Arginase purified from endophytic Pseudomonas aeruginosa IH2: Induce apoptosis through both cell cycle arrest and MMP loss in human leukemic HL-60 cells

Arginase is a therapeutic enzyme for arginine-auxotrophic cancers but their low anticancer activity, less proteolytic tolerance and shorter serum half-life are the major shortcomings. In this study, arginase from Pseudomonas aeruginosa IH2 was purified to homogeneity and estimated as 75 kDa on native-PAGE and 37 kDa on SDS-PAGE. Arginase showed optimum activity at pH 8 and temperature 35 °C. Mn²⁺ and Mg²⁺ ions enhanced arginase activity while, Li⁺, Cu²⁺, and Al³⁺ ions reduced arginase activity. In-vitro serum half-life of arginase was 36 h and proteolytic half-life against trypsin and proteinase-K was 25 and 29 min, respectively. Anticancer activity of arginase was evaluated against colon, breast, leukemia, and prostate cancer cell lines and lowest IC₅₀ (0.8 IU ml^-1) was found against leukemia cell line HL-60. Microscopic studies and flow cytometric analysis of Annexin V/PI staining of HL-60 cells revealed that arginase induced apoptosis in dose-dependent manner. Cell cycle analysis suggested that arginase induced cell cycle arrest in G0/G1 phase. The increasing level of MMP loss, ROS generation and decreasing level of SOD, CAT, GPx and GSH suggested that arginase treatment triggered dysfunctioning of mitochondria. The cleavage of caspase-3, PARP-1, activations of caspase-8, 9 and high expression of proapoptotic protein Bax, low expression of anti-apoptotic protein Bcl-2 indicated that arginase treatment activates mitochondrial pathway of apoptosis. Purified arginase did not exert cytotoxic effects on human noncancer cells. Our study strongly supports that arginase could be used as potent anticancer agent but further studies are required which are underway in our lab.

Protodioscin, Isolated from the Rhizome of Dioscorea tokoro Collected in Northern Japan is the Major Antiproliferative Compound to HL-60 Leukemic Cells

Abstract: Background: The rhizome of Oni-dokoro (a wild yam, Dioscorea tokoro) has extremely bitter taste and is not generally regarded edible;, however, in northern part of Japan, such as Iwate and a part of Aomori, it is used as health promoting food. To clarify the reason, we examined the biologically active compounds in the rhizome collected at Iwate and compared them from the other area in literature.

Methods: The acetonitrile extract from northern part of Japan was purified by bioassay-guided separation using antiproliferative activity to human leukemia HL-60 cell, and protodioscin (PD) was isolated and identified by instrumental analyses as the major active compound.

Results: PD known as a saponin with four sugar moieties, an inhibitor for platelet aggregation, and a low density lipoprotein (LPL) lowering agent, displayed strong growth inhibitory effect to HL-60. The literature search suggested that the rhizome from other area contained dioscin and other saponins with three sugar moieties as their major component. We assume that the edible and health promoting effect of the rhizome in the particular area is partially derived from these different components.

Conclusion: We were interested in the differences of utilization in the rhizome of wild yam Dioscorea tokoro, and examined the chemical composition in the rhizome to find protodioscin as antiproliferative compound to HL-60. In the report from other area, the rhizome exhibited dioscin as the major compound. Our study indicated that the protodioscin/dioscin composition varied regionally, although the reason is still needs to be investigated.