Proteasome Inhibitors Interrupt the Activation of Non-Canonical NF-κB Signaling Pathway and Induce Cell Apoptosis in Cytarabine-Resistant HL60 Cells

Over half of older patients with acute myeloid leukemia (AML) do not respond to cytotoxic chemotherapy, and most responders relapse because of drug resistance. Cytarabine is the main drug used for the treatment of AML. Intensive treatment with high-dose cytarabine can increase the overall survival rate and reduce the relapse rate, but it also increases the likelihood of drug-related side effects. To optimize cytarabine treatment, understanding the mechanism underlying cytarabine resistance in leukemia is necessary. In this study, the gene expression profiles of parental HL60 cells and cytarabine-resistant HL60 (R-HL60) cells were compared through gene expression arrays. Then, the differential gene expression between parental HL60 and R-HL60 cells was measured using KEGG software. The expression of numerous genes associated with the nuclear factor κB (NF-κB) signaling pathway changed during the development of cytarabine resistance. Proteasome inhibitors inhibited the activity of non-canonical NF-κB signaling pathway and induced the apoptosis of R-HL60 cells. The study results support the application and possible mechanism of proteasome inhibitors in patients with relapsed or refractory leukemia.

Preparation and Characterization of Pt-Doped Bi2MoO6 Nanocomposites and Its High PDT Efficiency on HL60 Cells

In this study, Pt-doped Bi2MoO6 nanocomposites were prepared by solvothermal and in situ reduction method. We used XRD, UV-Vis spectroscopy, TEM, EDS, and XPS to characterize its chemical properties. Results showed that the Pt-doped Bi2MoO6 nanocomposites had advantages of small size, good dispersion, and wide spectral response range. Then, we tested its biological toxicity and PDT efficiency on HL60 cells. Both pure Bi2MoO6 and Pt-doped Bi2MoO6 nanocomposites showed great biocompatibility after coincubated with leukemia cells for 12 h in the dark. As to PDT efficiency, Pt-doped Bi2MoO6 had a better-inactivated effect than pure Bi2MoO6. Furthermore, the PDT efficiency went up when atomic ratios and concentration increased. While the atomic ratio was 5% and the concentration was 1000 μg/mL, it reached the highest value at 85.2%. At last, we briefly analyzed the photocatalysis mechanism, which demonstrated that it was a potential photosensitizer with high efficiency for treating leukemia.

In Vitro and In Vivo Antiglycation Effects of Connarus ruber Extract

Accumulation of advanced glycation end products (AGEs) of the Maillard reaction has been implicated in the pathogenesis of diabetes and its complications. Connarus ruber has been used as a folk remedy for several diseases, including diabetes; however, its underlying mechanism has not yet been investigated. This study investigated the effects of C. ruber extract against glycation on collagen-linked AGEs in vitro and streptozotocin-induced diabetic rats (STZ-DM rats) in vivo. The antiglycation activities of C. ruber extract and aminoguanidine (AG) were examined using a collagen glycation assay kit. Nonfluorescent AGE, Nε-carboxymethyl lysine (CML), Nω-carboxymethyl arginine, and Nε-carboxyethyl lysine levels were measured via electrospray ionization-liquid chromatography-tandem mass spectrometry. The effect of the extract on the cytotoxicity of methylglyoxal (MG), a precursor of AGEs, was examined in HL60 cells. STZ-DM rats were treated with the extract for 4 wk, and the effect was assessed using biochemical markers in the serum and CML-positive cells in renal tissues. C. ruber extract dose-dependently inhibited the glycation of collagen and formation of nonfluorescent AGEs, which was comparable to AG, and it significantly attenuated MG-induced cytotoxicity in HL60 cells. Furthermore, the glycated albumin levels in STZ-DM rats decreased, the increase in serum lipid levels was reversed, and immunohistochemistry demonstrated that CML deposition in the glomerulus of STZ-DM rats significantly decreased. Although further studies are needed, C. ruber could be a potential therapeutic for preventing and progressing many pathological conditions, including diabetes.

Camel Milk Exosomes Potentiate The Anticancer Effect of Doxorubicin on Multidrug-Resistant Human Leukemia Hl60 Cells in Vitro and in Vivo

Background: Multidrug resistance (MDR) is one of the strategies developed by cancer cells to inhibit the anticancer potential of the majority of chemotherapeutic agents and almost results in treatment failure. Objective: This study aimed to evaluate the therapeutic potential of camel milk exosomes (CME) on multidrug-resistant human acute promyelocytic leukemia HL60 cells (HL60/RS) and to investigate whether this CME could potentiate the anticancer effect of Doxorubicin (DOX) and decrease its side effects. Results: CME alone or combined with DOX significantly induced HL60/RS cell viability loss, apoptosis, and cell cycle arrest at the G0/G1 phase, and downregulated MDR genes (Abcb1, Abcc1, Abcg2) as compared to cells treated with DOX alone. Additionally, CME and DOX co-treated nude mice had the lowest tumor volume, Abcb1, Abcc1, Abcg2, and Bcl2 expression, and the highest Bax and caspase3 expression in HL60/RS xenografts. This combined therapy also decreased DOX adverse effects as revealed by decreased liver damage enzymes and lipid peroxide (MDA) and increased hepatic antioxidant enzymes (SOD, CAT, GPx). Conclusion: CME increased sensitivity of HL60/RS to DOX through, at least in part, reduction of MDR genes, induction of apoptosis, and cell cycle arrest. Thus, CME may be used as safe adjuvants to DOX during cancer treatment. Keywords: Camel milk exosomes; Myeloid leukemia; HL60; Apoptosis; MDR

A Proteomic Analysis of the Effects of Yessotoxin and Di-Desulfoyessotoxin on Yeast and Mammalian Cells

<p>Yessotoxin (YTX) is a disulfated polycyclic polyether, produced by dinoflagellate algae. It is known to accumulate in edible shellfish, raising concerns about its potential risk to human health. YTX was initially classified as a diarrhetic shellfish poisoning toxin, due to commonly being extracted alongside toxins of this variety. However, YTX does not induce any of the effects characteristic of this group. A separate category for YTXs was established by the European Commission in 2002 and a limit of 1 mg/kg of shellfish meat was established. YTX has been shown to be an apoptosis inducer in a variety of cell lines in vitro. It has also been shown to be lethal to mice when administered by intra-peritoneal injection. However, when administered orally only limited toxicity is observed. The di-desulfated derivative (dsYTX) has also been shown to be lethal to mice following intra-peritoneal injection. However it causes damage mainly to the liver, whereas YTX appears to target the heart. The mechanism of action of YTX is still unknown. The goals of this project were to use proteomic techniques, to examine the effects of YTX and dsYTX on Saccharomyces cerevisiae and human promyelocytic leukemic blood leukocyte (HL60) cells. Young et al. (2009) showed that the major proteins affected by YTX in HepG2 cells were heterogeneous ribonucleoproteins (hnRNPs), lamins, cathepsins and heat shock proteins. HnRNPs had not previously been identified as possible targets of YTX. Alterations of hnRNP levels were also seen in HL60 cells treated with microtubule stabilising agents, peloruside A or paclitaxel (Wilmes et al., 2011, 2012). No differences in cell morphology or significant changes in protein abundance were observed when S. cerevisiae cells were exposed to YTX. A small number of significant changes in abundance were detected when these cells were exposed to dsYTX. The small number of protein changes seen is possibly due to poor toxin entrance into the cell through the yeast cell wall, lack of protein targets structurally homologous to those found in mammalian cells, or fast removal of the toxin through export pumps. Twenty-four hour incubation of HL60 cells with YTX resulted in increased cell death but no change in cell morphology. Treatment with dsYTX caused cells to aggregate into clusters and a 24% decrease in the number of live cells. Increases were found in the abundance of β-actin, hnRNP A and BiP proteins in response to dsYTX treatment. Decreases in these proteins were seen in HepG2 cells treated with YTX for 24 hours. As seen in S. cerevisiae cells, dsYTX had a greater effect in HL60 cells compared with YTX. Overall, the results provide some support for the previously identified effect on hnRNPs in mammalian cells exposed to YTX.</p>

A Proteomic Analysis of the Effects of Yessotoxin and Di-Desulfoyessotoxin on Yeast and Mammalian Cells

<p>Yessotoxin (YTX) is a disulfated polycyclic polyether, produced by dinoflagellate algae. It is known to accumulate in edible shellfish, raising concerns about its potential risk to human health. YTX was initially classified as a diarrhetic shellfish poisoning toxin, due to commonly being extracted alongside toxins of this variety. However, YTX does not induce any of the effects characteristic of this group. A separate category for YTXs was established by the European Commission in 2002 and a limit of 1 mg/kg of shellfish meat was established. YTX has been shown to be an apoptosis inducer in a variety of cell lines in vitro. It has also been shown to be lethal to mice when administered by intra-peritoneal injection. However, when administered orally only limited toxicity is observed. The di-desulfated derivative (dsYTX) has also been shown to be lethal to mice following intra-peritoneal injection. However it causes damage mainly to the liver, whereas YTX appears to target the heart. The mechanism of action of YTX is still unknown. The goals of this project were to use proteomic techniques, to examine the effects of YTX and dsYTX on Saccharomyces cerevisiae and human promyelocytic leukemic blood leukocyte (HL60) cells. Young et al. (2009) showed that the major proteins affected by YTX in HepG2 cells were heterogeneous ribonucleoproteins (hnRNPs), lamins, cathepsins and heat shock proteins. HnRNPs had not previously been identified as possible targets of YTX. Alterations of hnRNP levels were also seen in HL60 cells treated with microtubule stabilising agents, peloruside A or paclitaxel (Wilmes et al., 2011, 2012). No differences in cell morphology or significant changes in protein abundance were observed when S. cerevisiae cells were exposed to YTX. A small number of significant changes in abundance were detected when these cells were exposed to dsYTX. The small number of protein changes seen is possibly due to poor toxin entrance into the cell through the yeast cell wall, lack of protein targets structurally homologous to those found in mammalian cells, or fast removal of the toxin through export pumps. Twenty-four hour incubation of HL60 cells with YTX resulted in increased cell death but no change in cell morphology. Treatment with dsYTX caused cells to aggregate into clusters and a 24% decrease in the number of live cells. Increases were found in the abundance of β-actin, hnRNP A and BiP proteins in response to dsYTX treatment. Decreases in these proteins were seen in HepG2 cells treated with YTX for 24 hours. As seen in S. cerevisiae cells, dsYTX had a greater effect in HL60 cells compared with YTX. Overall, the results provide some support for the previously identified effect on hnRNPs in mammalian cells exposed to YTX.</p>

TCP1 increases drug resistance in acute myeloid leukemia by suppressing autophagy via activating AKT/mTOR signaling

T-complex protein 1 (TCP1) is one of the subunits of chaperonin-containing T complex (CCT), which is involved in protein folding, cell proliferation, apoptosis, cell cycle regulation, and drug resistance. Investigations have demonstrated that TCP1 is a factor being responsible for drug resistance in breast and ovarian cancer. However, the TCP1 role in acute myeloid leukemia (AML) remains elusive. In the present study, we discovered that the TCP1 expression was elevated in AML patients and high TCP1 expression was associated with low complete response rate along with poor overall survival. TCP1 showed higher expression in the adriamycin-resistant leukemia cell line HL60/A and K562/A, comparing to their respective parent cells HL60 and K562 cells. TCP1 inhibition suppressed drug resistance in HL60/A and K562/A cells, whereas TCP1 overexpression in HL60 cells incremented drug resistance, both in vitro and in vivo. Mechanistic investigations revealed that TCP1 inhibited autophagy and adriamycin-induced cell apoptosis, and TCP1-mediated autophagy inhibition conferred resistance to adriamycin-induced cell apoptosis. Furthermore, TCP1 interacted with AKT and mTOR to activate AKT/mTOR signaling, which negatively regulates apoptosis and autophagy. Pharmacological inhibition of AKT/mTOR signal particularly activated autophagy and resensitized TCP1-overexpressing HL60 cells to adriamycin. These findings identify a novel role of TCP1 regarding drug resistance in AML, which advise a new strategy for overcoming drug resistance in AML through targeting TCP1/AKT/mTOR signaling pathway.