Synthesis of BODIPY FL-tethered ridaifen-B, RID-B-BODIPY, and its localization in cancer cells.

We synthesized ridaifen-B boron dipyrromethene (RID-B-BODIPY) using 2-methyl-6-nitro benzoic anhydride (MNBA)-mediated dehydration condensation reaction between amino alkyl-tethered RID and BODIPY FL. Comparative experiments between dicyclohexylcarbodiimide (DCC) and MNBA for their coupling reactions demonstrated that MNBA is an effective condensation reagent for amines and BODIPY FL. A cell staining study with RID-B-BODIPY showed intracellular localization of BODIPY FL fluorescence, attributed to the RID-B structure, indicating the successful development of a tool for analyzing intracellular molecular behavior efficiently.

c-kit inhibitor masitinib induces reactive oxygen species-dependent apoptosis in c-kit-negative HepG2 cells.

Tumor-specific growth signal inhibition is a major anticancer strategy. Receptor tyrosine kinases (RTKs) are the most upstream receptors for growth signaling in cancer. Therefore, inhibition of RTKs has been proposed as an efficient therapeutic target. Masitinib, a c-kit inhibitor of the c-kit RTK, was developed to treat mastocytoma in dogs. In humans, however, the antitumor efficacy of masitinib was found to be attenuated against tumor cells with mutations of the c-kit gene. Here, we report that masitinib induced cell death via the intrinsic apoptotic pathway in HepG2, a c-kit-negative hepatocellular carcinoma cell line. In masitinib-treated HepG2 cells, increases in intracellular reactive oxygen species levels, loss of mitochondrial membrane potential, and cleavage of caspase-9 were observed, activating the intrinsic apoptotic pathway. Moreover, the cytotoxicity of masitinib to HepG2 cells was suppressed by treatment with the antioxidant N-acetyl-L-cysteine or a c-Jun N-terminal kinase/stress-activated protein kinase (JNKs) inhibitor. Thus, we demonstrated that the anticancer effects of masitinib are not due to its targeting c-kit, but rather to its targeting the redox balance via the JNK pathway in HepG2 cells. These results suggest that masitinib has the potential to provide a robust antitumor effect in tumor lesions and could also be applied to a broad range of other anticancer therapies.

Azoxystrobin Induces Apoptosis and Cell Cycle Arrest in Human Leukemia Cells Independent of p53 Expression.

BACKGROUND/AIM: Azoxystrobin (AZOX), a methoxyacrylate derivative, has potent antimicrobial and antitumor activities. Here, we report the anticancer effects of AZOX on the p53-negative human myelogenous leukemia cell line HL-60RG and the p53 positive human T-cell leukemia cell line MOLT-4F. MATERIALS AND METHODS: Using both leukemia cells, the anticancer effect of AZOX treatment was analyzed throughout the cell cycle. RESULTS: AZOX damaged both cell lines dose-dependently, and the cell damage rates were almost the same in both lines. Cell cycle distribution analysis showed that the treated MOLT-4F cells arrested at the S phase, whereas HL-60RG cells increased during the subG1 phase, suggesting that cell death was occurring. AZOX-induced cell death in HL-60RG was inhibited with the addition of uridine, which is used as a substrate for the salvage pathway of pyrimidine nucleotides. CONCLUSION: AZOX has p53-independent anticancer effects in leukemia cells, but the mechanisms underlying the damage differ between cell lines.

BRAP2 inhibits the Ras/Raf/MEK and PI3K/Akt pathways in leukemia cells, thereby inducing apoptosis and inhibiting cell growth.

Breast cancer susceptibility gene 1 (BRCA1)-associated protein 2 (BRAP2) is a novel protein that binds to BRCA1 and is located in the cytoplasm. BRAP2 has been demonstrated to bind to regulators of the Ras-Raf-MEK and PI3K/Akt pathways, both of which are involved in carcinogenesis. This suggests that BRAP2 may be capable of regulating both pathways. In the present study, the role of BRAP2 in both pathways was clarified during apoptosis and cell proliferation in a leukemia cell line. A BRAP2-deficient leukemia cell line was generated using CRISPR/Cas9, the BRAP2-deficient and parental cells were treated with a Ras, pan-Raf or PI3K inhibitor, and the changes in signal transduction, apoptosis and cell proliferation were evaluated. BRAP2 knockout attenuated the inhibition of signal transduction of the Ras-Raf-MEK and PI3K/Akt pathways by the Ras, pan-Raf or PI3K inhibitor. BRAP2 deletion also suppressed the cytotoxic and apoptotic effects of the Ras and pan-Raf inhibitors. However, the loss of BRAP2 did not suppress the cytotoxicity of the PI3K inhibitor but did suppress the PI3K inhibitor-induced inhibition of cell proliferation. The present results indicated that BRAP2 induces apoptosis and the inhibition of cell proliferation via regulating the Ras-Raf-MEK and PI3K/Akt pathways. In leukemia cells, because the Ras-Raf-MEK and PI3K/Akt pathways are activated aberrantly, the simultaneous inhibition of both pathways is desired. The current results indicated that enhancement of the function of BRAP2 may represent a new target in leukemia treatment.

Cell death induction by Ranunculus ternatus extract is independent of mitochondria and dependent on Caspase-7.

Ranunculus ternatus is a traditional Chinese medicine with an anticancer effect, but its underlying mechanism is unknown. In this study, we demonstrated by MTT assay that ethyl acetate extract (RTE) from R. ternatus exerts cytotoxic effects on human T cell lymphoma Jurkat cells. Then, to test the apoptosis induction ability of RTE to induce apoptosis, we analyzed phosphatidylserine exposure, DNA fragmentation, and caspase cleavage. RTE induced phosphatidylserine exposure and caspase-7 cleavage, but not caspase-3 cleavage. Sub-G1 cells were accumulated but DNA fragmentation was not observed. A pan-caspase inhibitor Z-Asp-CH2-DCB suppressed RTE-induced caspase cleavage and the above-described events. RTE also induced cell death in caspase-3 null human breast cancer MCF-7 cells, indicating that RTE-induced apoptotic-like cell death depends on the activation of one or more caspases, but not caspase-3. Moreover, RTE-induced cell death was not suppressed in Bcl-2 overexpressing Jurkat cells, suggesting that mitochondria were not involved in RTE-induced cell death. In conclusion, RTE-induced cell death was independent of mitochondria and dependent on caspase-7.

Novel Ridaifen-B Structure Analog Induces Apoptosis and Autophagy Depending on Pyrrolidine Side Chain.

Ridaifen (RID)-B is an analog derived from tamoxifen (TAM). TAM has an antitumor effect by acting as an antagonist to estrogen receptor (ER). However, TAM is known to also induces apoptosis in cancer cells that do not have ER. We clarified that RID-B induces cell death at a lower concentration than TAM, and causes ER-independent apoptosis and autophagy. Based on the results of previous studies, we assumed that RID-B had a unique target different from ER and examined structural activity correlation to determine what kinds of structural features are related to RID-B activity. As a result, we found there was activity even without one of phenyl groups (Ar3) in RID-B and revealed that two pyrrolidine side chains peculiar to RID-B are related to the action. Furthermore, analogs with shorter alkyl side chains induced autophagy, but analogs with certain length of alkyl side chains induced apoptosis. Also, although there is no doubt that RID-B induces apoptosis by causing mitochondrial injury, our results suggested that such injury induced mitochondria-selective autophagy. We revealed that RID-B induce mitophagy and that this mitophagy is a defense mechanism against RID-B. Our results suggest that autophagy was induced against apoptosis caused by mitochondrial dysfunction in RID-B, so the combination of autophagy inhibitor and anticancer-drug can be effective for cancer treatment.

Ashwagandha root extract exerts anti­inflammatory effects in HaCaT cells by inhibiting the MAPK/NF­κB pathways and by regulating cytokines.

A paste composed of the boiled leaves and roots of the Ashwagandha plant is used to cure ulcer and swelling in Ayurvedic medicine. However, the effects of the hot water extract of Ashwagandha roots (ASH­WEX), which is also used in Ayurveda, on skin have not been fully elucidated. Therefore, the present study investigated the anti­inflammatory activity of ASH­WEX on skin, by using the human keratinocyte cell line HaCaT. The results indicated that ASH­WEX significantly inhibited mRNA expression of inflammatory cytokines, including interleukin (IL)­8, IL­6, tumor necrosis factor (TNF­α), IL­1ß and IL­12, and promoted the mRNA expression of the anti­inflammatory cytokine transforming growth factor (TGF)­ß1 in HaCaT cells. In addition, ASH­WEX inhibited the lipopolysaccharide­induced phosphorylation of p38 and c­Jun N­terminal kinase, as well as the nuclear translocation of nuclear factor (NF)­κB p65. Downregulation of TNF­α mRNA and upregulation of TGF­ß1 mRNA were also observed in vivo following ASH­WEX treatment of mouse skin. In conclusion, the present study demonstrated that the anti­inflammatory effect of ASH­WEX may be due to its ability to suppress the NF­κB and mitogen­activated protein kinase pathways, and to modulate cytokine expression. These results suggest that ASH­WEX can potentially protect against skin inflammation.

Relationship Between Structure and Antiproliferative Activity of Novel 5-amino-4-cyanopyrazole-1-formaldehydehydrazono Derivatives on HL-60RG Human Leukemia Cells.

BACKGROUND: Pyrazole derivatives have been reported to have potent antimicrobial and anticancer activity. We recently synthesized and determined the effects of analogs, benzamidoxime derivatives, on mammalian cells and discovered that benzamidoximes had an antiproliferative effect. Here we synthesized and determined the anticancer effects of hydrazonopyrazole derivatives on a mammalian cancer cell line. MATERIALS AND METHODS: We synthesized 12 hydrazonopyrazole derivatives with several constant alkyl chain length or branched chains at the side chain to investigate their anticancer cell activity, using the human myelogenous leukemia cell line HL-60RG. RESULTS: Among all hydrazonopyrazole derivatives we synthesized, the hydrazonopyrazole derivative with a branched chain at the side chain rather than a constant alkyl chain significantly inhibited cell viability. The strongest hydrazonopyrazole derivative, 5-amino-4-cyanopyrazole-1-formaldehydehydrazono-3'-pentanal, tended to damage cells dose-dependently. This cell growth attenuation was a result of apoptosis, activating caspase-3 and fragmented DNA. CONCLUSION: Hydrazonopyrazole derivatives induced apoptosis of HL-60RG leukemia cells.

Caspase-6 Induces 7A6 Antigen Localization to Mitochondria During FAS-induced Apoptosis of Jurkat Cells.

BACKGROUND: Mitochondria are central to apoptosis. However, apoptosis progression involving mitochondria is not fully understood. A factor involved in mitochondria-mediated apoptosis is 7A6 antigen. 7A6 localizes to mitochondria from the cytosol during apoptosis, which seems to involve 'effector' caspases. In this study, we investigated the precise role of effector caspases in 7A6 localization to mitochondria during apoptosis. MATERIALS AND METHODS: Human T-cell lymphoma Jurkat cells were treated with an antibody against FAS. 7A6 localization was analyzed by confocal laser scanning microscopy and flow cytometry. Caspases activation was determined by western blot analysis. RESULTS: 7A6 localization to mitochondria during anti-FAS-induced apoptosis was significantly reduced by the caspase-6 inhibitor, N-acetyl-Val-Glu-Ile-Asp-aldehyde, but not by the caspase-3 inhibitor, N-acetyl-Asp-Asn-Leu-Asp-aldehyde, nor caspase-7/3 inhibitor, N-acetyl-Asp-Gln-Thr-Asp-aldehyde. Moreover, caspase-6 down-regulation suppressed 7A6 localization to mitochondria. CONCLUSION: Caspase-6 regulates 7A6 localization to mitochondria during anti-FAS-induced apoptosis of Jurkat cells.

Impaired CD98 signaling protects against graft-versus-host disease by increasing regulatory T cells.

Graft-versus-host disease (GvHD) is a major barrier to the broader use of allogenic hematopoietic stem cell transplantation for non-malignant clinical applications. A murine model of C57BL/6 to B6D2F1 acute GvHD was employed with T lymphocytes harboring a deletion of the CD98 heavy chain (CD98hc(-/-)) as donor cells. The CD98hc(-/-) resulted in lower responses to alloantigen stimulation in a mixed leukocyte reaction assay, and prevented the mortality associated with disease progression. The percentage of donor CD8 T lymphocytes was significantly decreased, while the percentage of Foxp3-positive regulatory T cells (Tregs) in recipients was increased by CD98hc(-/-). Decreased expression of FAS, FASL, ICOS, ICOSL, PD-1 and PD-L1 by donor CD8 T cells, and mRNA expression of cytotoxic T cell-related cytokines in the recipients were shown in those with CD98hc(-/-). Fewer infiltrated cells are found in the lungs, liver, tongue and skin of recipients with CD98hc(-/-) compared with the wild type recipients. Taken together, our data indicate that T cell-specific deletion of CD98hc can contribute to the prevention of GvHD development due to the attenuation of lymphocyte migration and by increasing the generation of Treg cells. These findings are expected to make it possible to develop novel approaches for the prevention of GvHD.

Use of high concentrations of dimethyl sulfoxide for cryopreservation of HepG2 cells adhered to glass and polydimethylsiloxane matrices.

Animal cells are generally cryopreserved in cryovials in a cell suspension state containing 5%-10% v/v dimethyl sulfoxide (DMSO) used as a cryoprotective agent. However, cryopreservation of cells in an attached state has not been intensively studied, and the effective freezing solution remains unknown. Here we determined the suitable DMSO concentration for the cryopreservation of human hepatoma HepG2 cells attached to glass and polydimethylsiloxane (PDMS) matrices coated with poly-l-lysine. With the use of the glass matrix, the rate of cell adhesion increased with the DMSO concentration up to 30% v/v in the freezing solution. In contrast, the cell-adhesion rate remained constant in the case of the PDMS matrix irrespective of the DMSO concentration between 10% v/v and 30% v/v. The viability of post-thawed cells attached to glass or PDMS matrix was also investigated. The viability was highest at the DMSO concentration of 20% v/v in the freezing solution. The DMSO concentration of 30% v/v, however, had a cytotoxic effect on the cell viability. Thus, the 20% v/v DMSO concentration was found to be most suitable for the cryopreservation of HepG2 cells in the attached state. This dose is high compared to the DMSO concentration used for the cryopreservation of cells in the suspended state.

N-(2-amino-5-chlorobenzoyl)benzamidoxime derivatives inhibit human leukemia cell growth.

BACKGROUND/AIM: Amidoxime derivatives have been previously reported to have potent anti-microbial and anti-tumor activity. Little is known about the tumor cell growth-inhibition mechanism of amidoximes, especially benzamidoxime derivatives. Herein we determined the effects of N-(2-amino-5-chlorobenzoyl)benzamidoxime analogs on mammalian cancer cells. MATERIALS AND METHODS: We synthesized four chloride-substituted benzamidoxime analogs from the original benzamidoxime to investigate their anticancer cell activity using the Jurkat T-cell lymphoma cell line and the human leukemia cell line HL-60RG. RESULTS: All amidoxime derivatives inhibited Jurkat and HL-60RG cell viability dose-dependently. Benzamidoximes tended to damage HL-60RG cells to a greater extent compared to Jurkat cells. Benzamidoximes with chloride substitutes caused a strong decrease in cell growth, and this cell growth attenuation was transient at 5 µM (below the half-maximal inhibitory concentration, IC50) but long-lasting at 10 µM (greater than the IC50). CONCLUSION: Benzamidoxime derivatives caused a transient cell-cycle delay at a low dose and cell death at a high dose.

5-Aminolevulinic acid combined with ferrous iron enhances the expression of heme oxygenase-1.

5-Aminolevulinic acid (5-ALA) is the naturally occurring metabolic precursor of heme. Heme negatively regulates the Maf recognition element (MARE) binding- and repressing-activity of the Bach1 transcription factor through its direct binding to Bach1. Heme oxygenase (HO)-1 is an inducible enzyme that catalyzes the rate-limiting step in the oxidative degradation of heme to free iron, biliverdin and carbon monoxide. These metabolites of heme protect against apoptosis, inflammation and oxidative stress. Monocytes and macrophages play a critical role in the initiation, maintenance and resolution of inflammation. Therefore, the regulation of inflammation in macrophages is an important target under various pathophysiological conditions. In order to address the question of what is responsible for the anti-inflammatory effects of 5-ALA, the induction of HO-1 expression by 5-ALA and sodium ferrous citrate (SFC) was examined in macrophage cell line (RAW264 cells). HO-1 expression induced by 5-ALA combined with SFC (5-ALA/SFC) was partially inhibited by MEK/ERK and p38 MAPK inhibitor. The NF-E2-related factor 2 (Nrf2) was activated and translocated from the cytosol to the nucleus in response to 5-ALA/SFC. Nrf2-specific siRNA reduced the HO-1 expression. In addition, 5-ALA/SFC increased the intracellular levels of heme in cells. The increased heme indicated that the inactivation of Bach1 by heme supports the upregulation of HO-1 expression. Taken together, our data suggest that the exposure of 5-ALA/SFC to RAW264 cells enhances the HO-1 expression via MAPK activation along with the negative regulation of Bach1.

Loss of Bcl-2 expression correlates with increasing sensitivity to apoptosis in differentiating ES cells.

Embryonic stem (ES) cells are derived from the inner cell mass of blastocysts and have a pluripotency to differentiate into a variety of cell types. ES cells have high resistance to environmental stress compared to functional cells, which can undergo apoptosis when stressed. We have investigated whether ES cells have resistance to multiple types of stress or selective stress. Phytosphingosine (PHS) and staurosporine (STS) were used as chemical stressors. PHS induced mitochondria-mediated apoptosis in several cell lines. STS is a protein kinase inhibitor that induces apoptosis even without mitochondrial involvement. PHS treatment damaged 3T3 mouse fibroblasts, but did not damage ES cells. STS damaged ES cells as well as 3T3 mouse fibroblasts at similar doses. Susceptibility to cell damage is correlated with the retention of the mitochondrial membrane potential. PHS treatment could induce DNA fragmentation in differentiated ES cells. Differences in cell-death susceptibility between the undifferentiated and differentiated states showed that the mitochondria-localised anti-apoptotic protein Bcl-2 was highly expressed in undifferentiated ES cells, which gradually decreased during differentiation. These results suggest that undifferentiated mouse ES cells have a high resistance to mitochondria-involved extracellular stress.

Aureobasidium pullulans culture supernatant significantly stimulates R-848-activated phagocytosis of PMA-induced THP-1 macrophages.

Toll-like receptors (TLRs), which recognize a wide range of microbial pathogens and pathogen-related products, play important roles in innate immunology. Macrophages have a variety of TLRs, and pathogen binding to TLR resulted in the activation of macrophages. R-848, an immune response modifier, is an analog of imidazoquinoline derivative and binds to an endosome-localized TLR to exert an anti-viral response on leukocytes. In the present study, we verified that co-treatment of R-848 with other TLR agonists would enhance immune response. The culture supernatant of Aureobasidium pullulans (A. pullulans, which contains predominantly soluble ß-glucan), which binds to cell membrane-localized TLR, and to C-type lectin receptor Dectin-1, was treated together with R-848 to THP-1 macrophages. Compared to R-848 treatment alone, co-treatment of R-848 with A. pullulans culture supernatant significantly augmented TNF-α and IL-12p40 cytokine expression. Next, we investigated whether or not apoptotic cell uptake would be increased by co-treatment of R-848 with A. pullulans culture supernatant. To detect engulfed apoptotic cells, we induced apoptosis in human lymphoma Jurkat cells by 5-fluorouracil and stained them with fluorescent dye 5(6)-carboxytetramethylrhodamine (TAMRA), whereas THP-1 macrophage was labeled with fluorescein isothiocyanate-anti-CD14 and determined the percentage increase in TAMRA-positive THP-1 macrophages by flow cytometric assay. Since R-848 or A. pullulans treatment alone stimulated THP-1 macrophages to induce phagocytosis, co-treatment of R-848 with A. pullulans culture supernatant significantly augmented phagocytosis of apoptotic Jurkat cells. These results suggest that the activation of several different innate immune receptor pathways may enhance the immune response of R-848 significantly.

Novel tamoxifen derivative Ridaifen-B induces Bcl-2 independent autophagy without estrogen receptor involvement.

Autophagy is a self-proteolysis process in eukaryotic cells that results in the sequestering of intracellular proteins and organelles in autophagosomes. Activation of autophagy progress continued growth of some tumors, instead extensive autophagy induces cell death. In a previous study, we synthesized a novel tamoxifen derivative, Ridaifen (RID)-B. RID-B induced mitochondria-involved apoptosis even in estrogen receptor (ER)-negative cells. Since tamoxifen induces autophagy other than apoptosis, we treated ER-negative Jurkat cells with RID-B in the present study. RID-B treatment induced apoptosis and LC3 and lysosome colocalization, which results in the formation of autolysosomes. Western blotting revealed that LC3 was converted to LC3-I to LC3-II with RID-B treatment, suggesting that RID-B induced autophagy without ER involvement. Moreover, overexpression of the anti-apoptotic protein Bcl-2 suppressed the RID-B-induced cell death, but not the induction of autophagy. These results presumed that RID-B-induced autophagy is independent of Bcl-2, making RID-B-induced autophagy different from RID-B-induced apoptosis. Since Beclin 1 level is unchanged during RID-B treatment, RID-B induced autophagy pathway is Bcl-2/Beclin1 independent noncanonical pathway.

Non-myeloablative conditioning is sufficient to induce mixed chimerism and subsequent acceptance of donor specific cardiac and skin grafts.

Organ transplant recipients have elevated cancer and viral infection risks due to immunosuppression and long-term results of organ transplantation remain unsatisfactory, mainly because of chronic rejection. The purpose of the current study is to establish a nonmyeloablative perioperative regimen, able to induce mixed chimerism and tolerance of allografts. To establish a nonmyeloablative perioperative regimen, we used Busulfan, an important component of many bone marrow transplantation preparative regimens for a variety of non-neoplastic diseases as an alternative to total body irradiation (TBI), and FTY720, a unique immunosuppression agent, inhibition lymphocyte homing. We found that creating a lymphohematopoietic chimera in which donor and recipient hematopoiesis coexist resulted in prolongation of the donor specific heart and skin allografts. Consistent with graft survival, pathological analysis indicated that the allografts from tolerant recipients were free of myocardial injury and had only a few interstitial infiltrates, and obliterative vasculopathy was not observed. Furthermore, we found that Treg cells were increased in the long-term graft acceptance recipients. Our data revealed that the therapeutic potential for using hematopoietic chimerism in non-myeloablated recipients hope the advances in rodent models described above in the development of minimal, nontoxic host conditioning regimens for mixed chimerism induction and subsequent acceptance of donor specific grafts.

SUTAF, a novel ß-methoxyacrylate derivative, promotes neurite outgrowth with extracellular signal-regulated kinase and c-jun N-terminal kinase activation.

ß-Methoxyacrylate antibiotics are well known to inhibit the fungal and yeast mitochondrial respiratory chain. In addition, ß-methoxyacrylates are reported to suppress the proliferation of mammalian cancer cells. Differentiation and cell-cycle arrest are closely related. The cell cycle of proliferating cells is suppressed before differentiation. In this study, we synthesized a ß-methoxyacrylate analog and treated neuronal differential model cells with it. We then estimated ß-methoxyacrylate's neurotrophic effect by inhibiting cell proliferation so as to orient neuronal differentiation. SUTAF-027-a novel ß-methoxyacrylate derivative, arrested the cell cycle and thereby suppressed the proliferation of PC12 rat pheochromocytoma cells and mouse neuroblastoma Neuro2a cells at very low treatment doses, as low as 1nM. However, a single SUTAF-027 treatment did not affect neuritogenesis. Surprisingly, however, co-treatment of SUTAF-027 and nerve growth factor (NGF) significantly augmented the NGF-induced neurite outgrowth of PC12. On the other hand, a single treatment of 1nM SUTAF-027 induced neurite outgrowth in Neuro2a cells. Further signal transduction mechanism studies revealed that SUTAF-027 induced the phosphorylation of extracellular signal-regulated kinase (ERK) and slight phosphorylation of c-jun N-terminal kinase (JNK). Moreover, inhibition of ERK and JNK blocked SUTAF-027-augmented neurite outgrowth. These results suggested that the novel ß-methoxyacrylate analog SUTAF-027 augmented neurite outgrowth by arresting the cell cycle and activating the ERK and JNK pathways.

Inulin stimulates phagocytosis of PMA-treated THP-1 macrophages by involvement of PI3-kinases and MAP kinases.

Inulin is a polysaccharide that enhances various immune responses, mainly to T and B cells, natural killer cells, and macrophages in vivo and in vitro. Previous reports describe that inulin activates macrophages indirectly by affecting the alternative complement pathway. In this study, we examined the direct effect of inulin on PMA-treated THP-1 macrophages. Inulin treatment did not stimulate the proliferation of THP-1 macrophages at all. However, inulin treatment significantly increased phagocytosis of the polystyrene beads without the influence of serum. Doses of around 1 mg/mL had the maximal effect, and significant progression of phagocytosis occurred at times treated over 6 h. Inulin augmented phagocytosis not only with polystyrene beads but also with apoptotic cancer cells. The inulin-induced phagocytosis uptake was suppressed in Toll-like receptor (TLR) 4 mutated C3H/HeJ mice peritoneal macrophages. Moreover, inulin-induced THP-1 macrophage TNF-α secretion was inhibited using a blocking antibody specific to TLR4, suggesting that TLR4 is involved in the binding of inulin to macrophages. Furthermore, we used specific kinase inhibitors to assess the involvement of inulin-induced phagocytosis and revealed that phosphoinositide 3-kinase and mitogen-activated protein kinase, especially p38, participated in phagocytosis. These results suggest that inulin affects macrophages directly by involving the TLR4 signaling pathway and stimulating phagocytosis for enhancing immunomodulation.

Rokitamycin induces a mitochondrial defect and caspase-dependent apoptosis in human T-cell leukemia Jurkat cells.

Macrolides are a well-known family of oral antibiotics whose antibacterial spectrum of activity covers most relevant bacterial species responsible for respiratory infectious disease. In recent years, it has been reported that macrolides have not only bactericidal activity but also direct immunomodulating activity in mammals. In this study, we observed new physiological activity of macrolides and examined whether various macrolides induce apoptosis in human leukemia cell lines. We investigated the effects of 13 different macrolides on the viability of Jurkat and HL-60 cells. Among all the macrolides used in this study, rokitamycin, a semisynthetic macrolide with a 16-member ring, effectively induced cell death. Rokitamycin induced DNA fragmentation and caspase activation, resembling the progression of apoptosis. Moreover, rokitamycin reduced the mitochondrial transmembrane potential and released cytochrome c from mitochondria to the cytosol, suggesting that mitochondrial perturbation is involved in rokitamycin-induced apoptosis. These results suggest that rokitamycin possesses not only bactericidal activity but also pro-apoptotic activity in human leukemia cells.