Diallyl disulfide downregulating RhoGDI2 induces differentiation and inhibit invasion via the Rac1/Pak1/LIMK1 pathway in human leukemia HL-60 cells.

Leukemia is a type of disease in which hematopoietic stem cells proliferate clonally at the genetic level. We discovered previously by high-resolution mass spectrometry that diallyl disulfide (DADS), which is one of the effective ingredients of garlic, reduces the performance of RhoGDI2 from APL HL-60 cells. Although RhoGDI2 is oversubscribed in several cancer categories, the effect of RhoGDI2 in HL-60 cells has remained unexplained. We aimed to investigate the influence of RhoGDI2 on DADS-induced differentiation of HL-60 cells to elucidate the association among the effect of inhibition or over-expression of RhoGDI2 with HL-60 cell polarization, migration and invasion, which is important for establishing a novel generation of inducers to elicit leukemia cell polarization. Co-transfection with RhoGDI2-targeted miRNAs apparently decreases the malignant biological behavior of cells and upregulates cytopenias in DADS-treated HL-60 cell lines, which increases CD11b and decreases CD33 and mRNA levels of Rac1, PAK1 and LIMK1. Meanwhile, we generated HL-60 cell lines with high-expressing RhoGDI2. The proliferation, migration and invasion capacity of such cells were significantly increased by the treated with DADS, while the reduction capacity of the cells was decreased. There was a reduction in CD11b and an increase in CD33 production, as well as an increase in the mRNA levels of Rac1, PAK1 and LIMK1. It also confirmed that inhibition of RhoGDI2 attenuates the EMT cascade via the Rac1/Pak1/LIMK1 pathway, thereby inhibiting the malignant biological behavior of HL-60 cells. Thus, we considered that inhibition of RhoGDI2 expression might be a new therapeutic direction for the treatment of human promyelocytic leukemia. The anti-cancer property of DADS against HL-60 leukemia cells might be regulated by RhoGDI2 through the Rac1-Pak1-LIMK1 pathway, which provides new evidence for DADS as a clinical anti-cancer medicine.

Antibacterial and antitumoral properties of 1,2,3-triazolo fused triterpenes and their mechanism of inhibiting the proliferation of HL-60 cells.

Antimicrobial resistance and cancer are two important problems affecting human health. Actively developing novel antibiotics and anticancer medicines is a priority. Natural pentacyclic triterpenoids have attracted wide attention due to their significant biological activities. In this study, a series of 1,2,3-triazolo fused triterpenoids (betulin, oleanolic acid and ursolic acid) were functionalized on the A-ring by an in-house developed multi-component triazolization reaction. The compounds were investigated for antitumoral activity in twelve cancer cell lines and were also tested for antibacterial activity against four bacteria. In terms of anticancer effects, compounds 5b-f and 8a-d displayed strong cytotoxic activity in pancreatic adenocarcinoma (Capan-1), chronic myeloid leukemia (Hap-1), acute myeloid leukemia (HL-60), acute lymphoblastic leukemia (Jurkat) and non-Hodgkin lymphoma (Rec-1) cell lines. Among them, compound 5f exhibited the most potent antiproliferative effect on HL-60 cells. Further pharmacological research confirmed that compound 5f caused mitochondrial dysfunction and arrested the cell cycle in the G0/G1 phase to induce apoptosis of HL-60 cells. In addition, compound 5f also induced autophagy to inhibit the proliferation of HL-60 cells. Antibacterial screening revealed that compounds 2a-g and 5a-d showed modest activity against Gram-negative bacteria (Escherichia coli and Salmonella enterica subsp. enterica) with especially compounds 2c and 2d being potent inhibitors of Salmonella enterica subsp. enterica growth. Because of their promising anticancer and antibacterial activity, this series of compounds deserve further study.

Neutrophil-like HL-60 cells expressing only GFP-tagged ß-actin exhibit nearly normal motility.

Observations of actin dynamics in living cells using fluorescence microscopy have been foundational in the exploration of the mechanisms underlying cell migration. We used CRISPR/Cas9 gene editing to generate neutrophil-like HL-60 cell lines expressing GFP-ß-actin from the endogenous locus (ACTB). In light of many previous reports outlining functional deficiencies of labeled actin, we anticipated that HL-60 cells would only tolerate a monoallelic edit, as biallelic edited cells would produce no normal ß-actin. Surprisingly, we recovered viable monoallelic GFP-ß-actin cells as well as biallelic edited GFP-ß-actin cells, in which one copy of the ACTB gene is silenced and the other contains the GFP tag. Furthermore, the edited cells migrate with similar speeds and persistence as unmodified cells in a variety of motility assays, and have nearly normal cell shapes. These results might partially be explained by our observation that GFP-ß-actin incorporates into the F-actin network in biallelic edited cells at similar efficiencies as normal ß-actin in unedited cells. Additionally, the edited cells significantly upregulate γ-actin, perhaps helping to compensate for the loss of normal ß-actin. Interestingly, biallelic edited cells have only modest changes in global gene expression relative to the monoallelic line, as measured by RNA sequencing. While monoallelic edited cells downregulate expression of the tagged allele and are thus only weakly fluorescent, biallelic edited cells are quite bright and well-suited for live cell microscopy. The nondisruptive phenotype and direct interpretability of this fluorescent tagging approach make it a promising tool for studying actin dynamics in these rapidly migrating and highly phagocytic cells.

Network-based method for drug target discovery at the isoform level.

Identification of primary targets associated with phenotypes can facilitate exploration of the underlying molecular mechanisms of compounds and optimization of the structures of promising drugs. However, the literature reports limited effort to identify the target major isoform of a single known target gene. The majority of genes generate multiple transcripts that are translated into proteins that may carry out distinct and even opposing biological functions through alternative splicing. In addition, isoform expression is dynamic and varies depending on the developmental stage and cell type. To identify target major isoforms, we integrated a breast cancer type-specific isoform coexpression network with gene perturbation signatures in the MCF7 cell line in the Connectivity Map database using the 'shortest path' drug target prioritization method. We used a leukemia cancer network and differential expression data for drugs in the HL-60 cell line to test the robustness of the detection algorithm for target major isoforms. We further analyzed the properties of target major isoforms for each multi-isoform gene using pharmacogenomic datasets, proteomic data and the principal isoforms defined by the APPRIS and STRING datasets. Then, we tested our predictions for the most promising target major protein isoforms of DNMT1, MGEA5 and P4HB4 based on expression data and topological features in the coexpression network. Interestingly, these isoforms are not annotated as principal isoforms in APPRIS. Lastly, we tested the affinity of the target major isoform of MGEA5 for streptozocin through in silico docking. Our findings will pave the way for more effective and targeted therapies via studies of drug targets at the isoform level.

Polyphenolic extracts of walnut (Juglans regia) green husk containing juglone inhibit the growth of HL-60 cells and induce apoptosis

BACKGROUND: Juglone is a naphthoquinone currently obtained by chemical synthesis with biological activities including antitumor activity. Additionally, juglone is present in the green husk of walnut, which suggests evaluating the effect of GH extracts on carcinogenic cell lines. RESULTS: Walnut green husk ethanolic extract was obtained as 169.1 mg juglone/100 g Green Husk and antioxidant activity (ORAC) of 44,920 µmol Trolox Equivalent/100 g DW Green Husk. At 1 µM juglone in HL-60 cell culture, green husk extract showed an antiproliferative effect, but pure juglone did not; under these conditions, normal fibroblast cells were not affected. A dose-dependent effect on mitochondrial membrane potential loss was observed. Apoptosis of HL-60 was detected at 10 µM juglone. Despite high ORAC values, neither purified juglone nor the extract showed protective effects on HL-60 cells under oxidative conditions. CONCLUSIONS: Green husk extract generates an antiproliferative effect in HL-60 cells, which is related to an induction of the early stages of apoptosis and a loss of mitochondrial membrane potential. The normal cells were not affected when juglone is present at concentrations of 1 µM, while at higher concentrations, there is loss of viability of both cancerous and healthy cells.

Cholestane glycosides from Ornithogalum saundersiae bulbs and the induction of apoptosis in HL-60 cells by OSW-1 through a mitochondrial-independent signaling pathway.

A search for cytotoxic cholestane glycosides from Ornithogalum saundersiae bulbs resulted in the isolation of three new OSW-1 analogues (1-3), a new cholestane bisdesmoside (4), a 5ß-cholestane diglycoside (5), and four new 24(23 → 22)-abeo-cholestane glycosides (6-9), together with 11 known cholestane glycosides (10-20), including OSW-1 (11). The structures of 1-9 were determined based on conventional spectroscopic analysis and chemical evidence. As expected, based on previous data, 1-3 exhibited potent cytotoxic activity against HL-60 human promyelocytic leukemia cells and A549 human lung adenocarcinoma cells. Furthermore, the ability of OSW-1 to induce apoptosis in HL-60 cells was examined. Aggregation of nuclear chromatin, accumulation of the sub-G1 cells, DNA fragmentation, and caspase-3 activation were assessed in HL-60 cells treated with OSW-1, providing evidence for OSW-1-induced apoptosis in HL-60 cells. No mitochondrial membrane potential or release of cytochrome c into the cytoplasm were observed in the OSW-1-treated apoptotic HL-60 cells, indicating that a mitochondria-independent signaling pathway is involved in apoptotic cell death.

Pregnane glycosides from the bark of Marsdenia cundurango and their cytotoxic activity.

Seven new pregnane glycosides (1-7) and eight known compounds (8-15) were isolated from the bark of Marsdenia cundurango (Asclepiadaceae). The structures of 1-7 were determined by spectroscopic analysis, including two-dimension NMR spectroscopy, chemical transformations, and chromatographic analysis of the hydrolyzed products. The isolated compounds 1-15 were evaluated for their cytotoxic activity against HL-60 human leukemia cells, A549 human lung adenocarcinoma cells, and TIG-3 normal human lung cells, including apoptosis-inducing activity of a representative pregnane glycoside in HL-60 cells.

Uric acid disrupts hypochlorous acid production and the bactericidal activity of HL-60 cells.

Uric acid is the end product of purine metabolism in humans and is an alternative physiological substrate for myeloperoxidase. Oxidation of uric acid by this enzyme generates uric acid free radical and urate hydroperoxide, a strong oxidant and potentially bactericide agent. In this study, we investigated whether the oxidation of uric acid and production of urate hydroperoxide would affect the killing activity of HL-60 cells differentiated into neutrophil-like cells (dHL-60) against a highly virulent strain (PA14) of the opportunistic pathogen Pseudomonas aeruginosa. While bacterial cell counts decrease due to dHL-60 killing, incubation with uric acid inhibits this activity, also decreasing the release of the inflammatory cytokines interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF- α). In a myeloperoxidase/Cl-/H2O2 cell-free system, uric acid inhibited the production of HOCl and bacterial killing. Fluorescence microscopy showed that uric acid also decreased the levels of HOCl produced by dHL-60 cells, while significantly increased superoxide production. Uric acid did not alter the overall oxidative status of dHL-60 cells as measured by the ratio of reduced (GSH) and oxidized (GSSG) glutathione. Our data show that uric acid impairs the killing activity of dHL-60 cells likely by competing with chloride by myeloperoxidase catalysis, decreasing HOCl production. Despite diminishing HOCl, uric acid probably stimulates the formation of other oxidants, maintaining the overall oxidative status of the cells. Altogether, our results demonstrated that HOCl is, indeed, the main relevant oxidant against bacteria and deviation of myeloperoxidase activity to produce other oxidants hampers dHL-60 killing activity.

The Effect of Bone Marrow Mesenchymal Stem Cells on the Granulocytic Differentiation of HL-60 Cells.

OBJECTIVE: Mesenchymal stem cells (MSCs) are multipotent stromal cells that can differentiate into a variety of cell types. They control the process of hematopoiesis by secreting regulatory cytokines and growth factors and by the expression of important cell adhesion molecules for cell-to-cell interactions. This investigation was intended to examine the effect of bone marrow (BM)-derived MSCs on the differentiation of HL-60 cells according to morphological evaluation, flow cytometry analysis, and gene expression profile. MATERIALS AND METHODS: The BM-MSCs were cultured in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum (FBS). After the third passage, the BM-MSCs were irradiated at 30 Gy. To compare how the HL-60 cells differentiated in groups treated differently, HL-60 cells were cultured in RPMI-1640 and supplemented with 10% FBS. The HL-60 cells were seeded into six-well culture plates and treated with all-trans-retinoic acid (ATRA), BM-MSCs, or BM-MSCs in combination with ATRA, while one well remained as untreated HL-60 cells. The expression levels of the granulocyte subset-specific genes in the HL-60 cells were assayed by real-time polymerase chain reaction. RESULTS: Our results revealed that BM-MSCs support the granulocytic differentiation of the human promyelocytic leukemia cell line HL-60. CONCLUSION: Based on the results of this study, we concluded that BM-MSCs may be an effective resource in reducing or even preventing ATRA's side effects and may promote differentiation for short medication periods. Though BM-MSCs are effective resources, more complementary studies are necessary to improve this differentiation mechanism in clinical cases.

Application of selected reaction monitoring and parallel reaction monitoring for investigation of HL-60 cell line differentiation.

Targeted mass spectrometry represents a powerful tool for investigation of biological processes. The convenient approach of selected reaction monitoring using stable isotope-labeled peptide standard (SIS) is widely applied for protein quantification. Along with this method, high-resolution parallel reaction monitoring has been increasingly used for protein targeted analysis. Here we applied two targeted approaches (selected reaction monitoring with SIS and label-free parallel reaction monitoring) to investigate expression of 11 proteins during all-trans retinoic acid-induced differentiation of HL-60 cells. In our experiments, we have determined the proteins expression ratio at 3, 24, 48, and 96 h after all-trans retinoic acid treatment in comparison with 0 h, respectively. Expression profiles of four proteins (VAV1, PRAM1, LYN, and CEBPB) were highly correlated ( r > 0.75) and FGR expression was detected on proteome level starting from 24 h by both techniques. For prominent differences (fold change ≥ 2) label-free parallel reaction monitoring is not inferior to selected reaction monitoring with isotopically labeled peptide standards. Differentially expressed proteins, that have been determined in our study, can be considered as potential drug targets for acute myeloid leukemia (AML) treatment.

[Expression of ICAT and Wnt signaling-related proteins in the monocytic differentiation of HL-60 cells induced by a new steroidal drug NSC67657].

OBJECTIVE: To investigate the expression of mRNA and proteins of ß-catenin, TCF-4 (ICAT) and Wnt signaling pathway-related genes in the monocytic differentiation of acute myeloid leukemia HL-60 cells induced by a new steroidal drug NSC67657. METHODS: Wright's staining and α-NBE staining were used to observe the differentiation of HL-60 cells after 5 days of 10 µmol/L NSC67657 treatment. Flow cytometry (FCM) was used to detect the differentiation and cell cycles. The expressions of mRNA and proteins of ICAT and Wnt signaling pathway-related factors, including ß-catenin, TCF-4, c-myc, cyclin D1 and TCF-1 before and after differentiation, were detected by RT-PCR and Western blot. RESULTS: Morphological observation showed that NSC67657 induced monocytic differentiation of HL-60 cells. At 5 days after 10 µmol/L NSC67657 treatment, the number of CD14(+) HL-60 cells was (94.37±2.84)%, significantly higher than the (1.31±0.09)% in control group (P<0.01). The flow cytometry assay revealed that NSC67657 induced (76.46±2.83)% of G1/G0 phase arrest, significantly higher than that of (59.40±5.42)% in the control group (P<0.05), while the S phase cells were of (18.76±0.98)%, significantly lower than that of (34.38±2.61) % in the control group (P<0.05). The NSC67657 treatment also up-regulated the expression of ICAT mRNA and protein, and down-regulated the expression of ß-catenin mRNA and protin (P<0.01 for all). However, the nuclear expression of ß-catenin was down-regulated (P<0.01). The NSC67657 treatment induced nonsignificant alterations of TCF-4 mRNA, total protein and nuclear protein in the HL-60 cells (P>0.05 for all). The target genes of Wnt signaling pathway, including c-myc, cyclinD1 and TCF-1 mRNA and proteins in the HL-60 cells were significantly down-regulated after NSC67657 treatment (P<0.05). CONCLUSIONS: The new steroidal drug NSC67657 induces monocytic differentiation of HL-60 cells, and down-regulates the expression of ß-catenin and target genes of Wnt signaling pathway. These results indicate that Wnt signaling pathway may be directly or indirectly involved in the monocytic differentiation process of HL-60 cells.

Proteomic profile of aminoglutethimide-induced apoptosis in HL-60 cells: Role of myeloperoxidase and arylamine free radicals.

In this study, the cellular effects resulting from the metabolism of aminoglutethimide by myeloperoxidase were investigated. Human promyelocytic leukemia (HL-60) cells were treated with aminoglutethimide (AG), an arylamine drug that has a risk of adverse drug reactions, including drug-induced agranulocytosis. HL-60 cells contain abundant amounts of myeloperoxidase (MPO), a hemoprotein, which catalyzes one-electron oxidation of arylamines using H2O2 as a cofactor. Previous studies have shown that arylamine metabolism by MPO results in protein radical formation. The purpose of this study was to determine if pathways associated with a toxic response could be determined from conditions that produced protein radicals. Conditions for AG-induced protein radical formation (with minimal cytotoxicity) were optimized, and these conditions were used to carry out proteomic studies. We identified 43 proteins that were changed significantly upon AG treatment among which 18 were up-regulated and 25 were down-regulated. The quantitative proteomic data showed that AG peroxidative metabolism led to the down-regulation of critical anti-apoptotic proteins responsible for inhibiting the release of pro-apoptotic factors from the mitochondria as well as cytoskeletal proteins such as nuclear lamina. This overall pro-apoptotic response was confirmed with flow cytometry which demonstrated apoptosis to be the main mode of cell death, and this was attenuated by MPO inhibition. This response correlated with the intensity of AG-induced protein radical formation in HL-60 cells, which may play a role in cell death signaling mechanisms.

The cytokine response in THP-1 (monocyte) and HL-60 (neutrophil-differentiated) cells infected with different genotypes of Helicobacter pylori strains.

BACKGROUND/AIMS: Helicobacter pylori (H. pylori) is a microaerophilic bacterium related with peptic ulcer and gastric cancer. Its virulence factors include cytotoxin-associated gene A (CagA) and vacuolating cytotoxin gene A (VacA) proteins. Cytokine release inducted by H. pylori colonization has an important role in pathogenesis of H. pylori. The severity of gastric pathologies depends on the H. pylori genotypes found in different geographical regions. We aimed to determine the relationship between different H. pylori genotypes and their effects on the cytokine release levels. MATERIALS AND METHODS: ureC, cagA, vacAs1/s2, vacAm1/m2, and blood group antigen-binding adhesion protein A2 (babA2) virulence related genes were investigated in 21 H. pylori strains. Genotyping of 21 strains were made due to the presence of cagA, vacAs1/s2, vacAm1/m2, and babA2 genes. The H. pylori strains were cultured together with THP-1 and neutrophil-differentiated Human promyelocytic leukemia cells (HL-60) cells. The levels of cytokines interleukin (IL)-1ß, IL-6, IL-8, IL-12, tumor necrosis factor-alpha (TNF-α), and IL-10 in these cells were measured after co-culturing with H. pylori strains. RESULTS: The following five different genotypes were detected: Genotype1: cagA and vacAs1m2; Genotype2: cagA and vacAs1m1; Genotype3: cagA, vacAs1m2, and babA2; Genotype4: vacAs2m2; and Genotype5: cagA and vacAs2m2. All these genotypes significantly induced the levels of IL-1ß, IL-6, IL-8, IL 10, and TNF-α in THP-1 cells. Genotype 5 caused higher amounts of IL-1ß, IL-6, TNF-α, and IL-10, whereas genotype 1 induced the highest levels of IL-8. In neutrophil-differentiated HL-60 cells, genotype 4 increased IL-6 levels and genotype 3 and 4 elevated IL-8 levels significantly. CONCLUSION: These results suggested that cytokine response of the host varies depending on the specific immune response of the host against different H. pylori strains.

The synthetic tryptanthrin analogue suppresses STAT3 signaling and induces caspase dependent apoptosis via ERK up regulation in human leukemia HL-60 cells.

Tryptanthrin is a natural product which has been reported to have several medicinal properties. In this study, we tried to investigate the detailed molecular mechanism of its bromo analogue (TBr), a potent cytotoxic agent in the induction of cancer cell death. It was found that TBr primarily targets STAT3 and ERK signaling during the induction of apoptosis in several human leukemia cell lines. In HL-60 cells, TBr treatment caused early down regulation of p-STAT3 with concomitant up regulation of p-ERK which led to the activation of intrinsic and extrinsic pathways of apoptosis. The mechanism of TBr mediated inhibition of p-STAT3 was found to be due to the activation of ubiquitin dependent degradation of tyrosine 705 and serine 727 p-STAT3. As IL-6 is the main driver of the STAT3 pathway, the effect of TBr on cell death was subdued when treated in the combination with IL-6 in HL60 cells. Interestingly, PD98059 significantly reduced the apoptotic effects of TBr, thus showing the direct involvement of p-ERK in TBr mediated cell death. It was further shown that apoptotic protein Bax silencing in HL-60 cells resists TBr mediated ERK dependent apoptosis. In summary, for the first time we report the mechanism of TBr mediated cell death in human leukemia cell lines by targeting STAT3 and ERK pathways.

[Inhibitory effect of 14-3-3ζ on the proliferation of HL-60 cells and HL-60/VCR cells].

This study was aimed to investigate the expression and role of 14-3-3ζ in the AML cell lines: sensitive HL-60 and drug-resistant HL-60/VCR cells. Semi-quantitative RT-PCR and Western blot were respectively used to examine the expression of mdr1 mRNA and Pgp in AML cell lines to validate the results of microarray. Western blot was performed to investigate the expression of Pgp, 14-3-3ζ, and anti-apoptosis protein BCL-2, MCL-1 proteins. Immunofluorescence assay was used to detect the subcellular location of 14-3-3ζ protein in HL-60 and HL-60/VCR cells by laser scanning confocal microscopy. Transduction with siRNA was used to silence 14-3-3ζ in AML cell lines. Cell count method and flow cytometry of cell cycle were used to analyze the changes of growth of AML cells. The results found that mdr1 mRNA and Pgp did not expressed in HL-60 cells, but significantly overexpressed in HL-60/VCR cells. Except 14-3-3σ, the expression of other subtypes of 14-3-3 was higher in HL-60/VCR cells than that in HL-60 cells, especially 14-3-3ζ. The higher expression of 14-3-3ζ, BCL-2, MCL-1 protein was observed in HL-60/VCR cells than that in HL-60 cells. These results were same results from gene chip. It was also noticed that 14-3-3ζ was located in the cytoplasma and nuclei of AML cell lines, especially over-expressed in HL-60/VCR cells. Furthermore, suppression of 14-3-3ζ by RNA interference resulted in inhibition of the proliferation of AML cells with decreased protein expression of BCL-2 and MCL-1, especially in HL-60/VCR cells. It is concluded that 14-3-3ζ plays an important role in proliferation of AML cells and associates with BCL-2 and MCL-1 expression. These results suggested that development of therapy targeting 14-3-3ζ may provide novel, effective strategies for refractory and relapsed AML.

miR-30d, miR-181a and miR-199a-5p cooperatively suppress the endoplasmic reticulum chaperone and signaling regulator GRP78 in cancer.

GRP78, a major endoplasmic reticulum chaperone and signaling regulator, is commonly overexpressed in cancer. Moreover, induction of GRP78 by a variety of anti-cancer drugs, including histone deacetylase inhibitors, confers chemoresistance to cancer, thereby contributing to tumorigenesis. Thus, therapies aimed at decreasing GRP78 levels, which results in the inhibition of tumor cell proliferation and resensitization of tumor cells to chemotherapeutic drugs may hold promise for cancer treatment. Despite advances in our understanding of GRP78 actions, little is known about endogenous inhibitors controlling its expression. As endogenous regulators, microRNAs (miRNAs) play important roles in modulating gene expression; therefore, we sought to identify miRNA(s) that target GRP78, under the hypothesis that these miRNAs may serve as therapeutic agents. Here, we report that three miRNAs (miR-30d, miR-181a, miR-199a-5p) predicted to target GRP78 are down-regulated in prostate, colon and bladder tumors, and human cancer cell lines. We show that in C42B prostate cancer cells, these miRNAs down-regulate GRP78 and induce apoptosis by directly targeting its 3' untranslated region. Importantly, we demonstrate that the three miRNAs act cooperatively to decrease GRP78 levels, suggesting that multiple miRNAs may be required to efficiently control the expression of some genes. In addition, delivery of multiple miRNAs by either transient transfection or lentivirus transduction increased the sensitivity of cancer cells to the histone deacetylase inhibitor, trichostatin A, in C42B, HCT116 and HL-60 cells. Together, our results indicate that the delivery of co-transcribed miRNAs can efficiently suppress GRP78 levels and GRP78-mediated chemoresistance, and suggest that this strategy holds therapeutic potential.

The preparation of HL-60 cells vaccine expressing BCG heat shock protein 70 and detection of its immunogenicity in vitro.

Gene-modified cell vaccines are the best way to achieve the immunotherapy for all types of acute leukemia. In this study, the recombinant eukaryotic expression vector (pDisplay-HSP70) of heat shock protein 70 (HSP70) of Bacille Calmette-Guérin (BCG) was constructed by amplifying the whole BCG HSP70 gene using polymerase chain reaction (PCR) and sub-cloning into the polyclone endonuclease sites in pDisplay. Then the HL-60 cell vaccine expressing the protein onto the cell surface was prepared by lipofectamine transfection and its anti-tumor effect and mechanism were further studied. Results showed that the fragment of BCG HSP70 was consistent with Mycobacterium tuberculosis HSP70 gene published in GeneBank. DNA sequencing showed that the recombinant vector was correctly constructed and named pDisplay-HSP70. After BCG HSP70 gene transfection, the yellow-green fluorescence on the HL-60 cells surface was observed under a fluorescence microscope. The immunogenicity of HSP70-transfected HL-60 cells exhibited upregulated proliferation of lymphocytes, increased cytokine secretion (IFN-γ) and enhanced killing activity. These results suggested that gene transfection of BCG HSP70 could significantly enhance the immunogenicity of HL-60 cells. It may be used as a suitable candidate gene-modified cell vaccine for cancer immunotherapy.

Inactivation of staphylococcal phenol soluble modulins by serum lipoprotein particles.

Staphylococcus aureus virulence has been associated with the production of phenol soluble modulins (PSM). PSM are known to activate, attract and lyse neutrophils. However, the functional characterizations were generally performed in the absence of human serum. Here, we demonstrate that human serum can inhibit all the previously-described activities of PSM. We observed that serum can fully block both the cell lysis and FPR2 activation of neutrophils. We show a direct interaction between PSM and serum lipoproteins in human serum and whole blood. Subsequent analysis using purified high, low, and very low density lipoproteins (HDL, LDL, and VLDL) revealed that they indeed neutralize PSM. The lipoprotein HDL showed highest binding and antagonizing capacity for PSM. Furthermore, we show potential intracellular production of PSM by S. aureus upon phagocytosis by neutrophils, which opens a new area for exploration of the intracellular lytic capacity of PSM. Collectively, our data show that in a serum environment the function of PSM as important extracellular toxins should be reconsidered.

Enhancement of interleukin-8-induced chemotactic response and reactive oxygen species production in HL-60 cells expressing CXCR1.

Neutrophils play a pivotal role in immunity against infection by ingesting and killing invading microbes. Neutrophils isolated from human peripheral blood have been used for a number of studies conducted for evaluation of immunomodulating drugs, cytokines, and microbe products. Human promyelocytic leukemia cells, HL-60, have been extensively studied because they can differentiate into neutrophil-like cells by addition of all-trans retinoic acid or dimethyl sulfoxide. For a system that would always allow experimental use of granulocytic cells in a uniformly activated state, we have established HL-60 cell lines with increased migratory activity by transducing the CXC chemokine receptor 1 (CXCR1) gene. When these cell lines were primed with CXC chemokine ligand 8 (IL-8), a slight increase in reactive oxygen species production induced by phorbol myristate acetate (PMA) or zymosan A stimuli was observed. A significance increase in migratory activity was noticed when the HL-60 cells transduced CXCR1 were stimulated with IL-8 in the Boyden chamber method. The gene-transduced HL-60 cell lines may be used as a substitute for neutrophils in screening the effects of various immunomodulating drugs on the migratory activity induced by IL-8.

Characterization of BmKbpp, a multifunctional peptide from the Chinese scorpion Mesobuthus martensii Karsch: gaining insight into a new mechanism for the functional diversification of scorpion venom peptides.

BmKbpp is a novel cationic and α-helical peptide from the Chinese scorpion Mesobuthus martensii Karsch, of which function or biological activity has not been characterized so far. Here we showed that BmKbpp possesses strong antimicrobial activity against both Gram-positive and Gram-negative bacteria with a MIC range from 2.3 µM to 68.2 µM for the majority of tested bacteria. BmKbpp also inhibits the growth of tested fungi with an IC50 range from 0.2 µM to 3.1 µM. Because BmKbpp potently inhibits the growth of some antibiotics-resistant pathogens, and shows very weak hemolytic activity, it has considerable potentials for therapeutic applications. Moreover, we found that BmKbpp markedly inhibits the superoxide production in granulocytes or HL-60 cells at the concentrations of submicromolar level; this suggests that BmKbpp can act as a signaling molecule involving innate immune regulation at low concentrations. The C-terminal region of BmKbpp (BmKbpp-C) shows 72% similarity to the peptide K-12, a bradykinin-potentiating peptide. We found that both BmKbpp and BmKbpp-C possess bradykinin-potentiating activity, and the activity of BmKbpp-C is stronger than that of BmKbpp. PCR amplification for the genomic gene of BmBpp showed that it is not a continuous sequence in the genome; it suggests that BmKbpp could come from a recombination event in transcript level. Taken together, our data suggest that multi-functionalization of a single peptide, which is probably mediated by trans-splicing, could be a new mechanism for the functional diversification of scorpion venom peptides.