De novo pyrimidine biosynthetic complexes support cancer cell proliferation and ferroptosis defence.

De novo pyrimidine biosynthesis is achieved by cytosolic carbamoyl-phosphate synthetase II, aspartate transcarbamylase and dihydroorotase (CAD) and uridine 5'-monophosphate synthase (UMPS), and mitochondrial dihydroorotate dehydrogenase (DHODH). However, how these enzymes are orchestrated remains enigmatical. Here we show that cytosolic glutamate oxaloacetate transaminase 1 clusters with CAD and UMPS, and this complex then connects with DHODH, which is mediated by the mitochondrial outer membrane protein voltage-dependent anion-selective channel protein 3. Therefore, these proteins form a multi-enzyme complex, named 'pyrimidinosome', involving AMP-activated protein kinase (AMPK) as a regulator. Activated AMPK dissociates from the complex to enhance pyrimidinosome assembly but inactivated UMPS, which promotes DHODH-mediated ferroptosis defence. Meanwhile, cancer cells with lower expression of AMPK are more reliant on pyrimidinosome-mediated UMP biosynthesis and more vulnerable to its inhibition. Our findings reveal the role of pyrimidinosome in regulating pyrimidine flux and ferroptosis, and suggest a pharmaceutical strategy of targeting pyrimidinosome in cancer treatment.

Identification of purine biosynthesis as an NADH-sensing pathway to mediate energy stress.

An enhanced NADH/NAD+ ratio, termed reductive stress, is associated with many diseases. However, whether a downstream sensing pathway exists to mediate pathogenic outcomes remains unclear. Here, we generate a soluble pyridine nucleotide transhydrogenase from Escherichia coli (EcSTH), which can elevate the NADH/NAD+ ratio and meantime reduce the NADPH/NADP+ ratio. Additionally, we fuse EcSTH with previously described LbNOX (a water-forming NADH oxidase from Lactobacillus brevis) to resume the NADH/NAD+ ratio. With these tools and by using genome-wide CRISPR/Cas9 library screens and metabolic profiling in mammalian cells, we find that accumulated NADH deregulates PRPS2 (Ribose-phosphate pyrophosphokinase 2)-mediated downstream purine biosynthesis to provoke massive energy consumption, and therefore, the induction of energy stress. Blocking purine biosynthesis prevents NADH accumulation-associated cell death in vitro and tissue injury in vivo. These results underscore the pathophysiological role of deregulated purine biosynthesis in NADH accumulation-associated disorders and demonstrate the utility of EcSTH in manipulating NADH/NAD+ and NADPH/NADP+.

Matrine, a potential c-Myc inhibitor, suppresses ribosome biogenesis and nucleotide metabolism in myeloid leukemia.

Previous studies have shown that matrine, a natural compound extracted from the herb Sophora flavescens, has a good anti-leukemia effect, but its key target and mechanism remains unclear. Here, we found that only c-Myc could respond rapidly to matrine treatment in three myeloid leukemia cell lines, and matrine inhibited both transcription and translation of c-Myc. Ribosome biogenesis and nucleotide metabolism, the key downstream of c-Myc, were significantly suppressed after matrine treatment. Therefore, our results confirmed that matrine is a special c-Myc inhibitor which suppresses ribosome biogenesis and nucleotide metabolism by inhibiting c-Myc in myeloid leukemia. This study provides scientific basis for the development of matrine derivatives to c-Myc-driven cancers.

Compound 968 reverses adriamycin resistance in breast cancer MCF-7ADR cells via inhibiting P-glycoprotein function independently of glutaminase.

Adriamycin (ADR) is a chemotherapeutic drug widely utilized to treat multiple types of cancers; however, the clinical efficacy of ADR is compromised due to the development of drug resistance in patients. The combination of drugs with ADR may provide a better therapeutic regimen to overcome this obstacle. Glutaminase (GLS) has been explored as a therapeutic cancer target, and its inhibition also results in increased sensitivity of tumor cells to chemotherapeutic agents. This study aimed to investigate whether GLS inhibition could reverse ADR resistance. We treated the ADR-resistant MCF-7 (MCF-7ADR) cells with a GLS inhibitor, compound 968 or CB-839, in combination with ADR. We found that compound 968, rather than CB-839, together with ADR synergistically inhibited the cell viability. These results indicated that compound 968 reversed ADR resistance in MCF-7ADR cells independently of GLS. Moreover, we modified the structure of compound 968 and finally obtained a compound 968 derivative, SY-1320, which was more potent than compound 968 in eliminating the drug resistance in MCF-7ADR cells. Furthermore, using drug affinity responsive target stability and streptavidin-biotin immunoprecipitation assays, we demonstrated that SY-1320 could specifically target P-glycoprotein (P-gp) and increase ADR accumulation through inhibition of P-gp, thereby resulting in cell death in MCF-7ADR cells. Together, our findings indicate that compound 968 or SY-1320 might be a promising drug for new combination chemotherapy in breast cancer to overcome the drug resistance.

Morinda citrifolia (Noni) Juice Suppresses A549 Human Lung Cancer Cells via Inhibiting AKT/Nuclear Factor-κ B Signaling Pathway.

OBJECTIVE: To study the mechanism of the anti-tumor effect of Morinda citrifolia (noni). METHODS: The influences of noni juice on cell proliferation, apoptosis, invasion, migration and the activity of AKT/nuclear factor- κ B (NF- κ B) signaling pathway in A549 human lung cancer cells were detected by MTT, cell counting kit-8, colony formation, Annexin V/PI double labeling, transwell, scratch test and immunoblotting assay, respectively. A549 cells were inoculated into the right axilla of nude mice, followed by noni juice treatment. The body weight of the nude mice was weighed, and the tumor volume and weight were measured. Cell proliferation and expression of apoptosis-related proteins were measured by immunohistochemistry, and the activity of NF- κ B signaling pathway was measured by immunoblotting. RESULTS: The in vitro studies showed that noni juice inhibited the A549 cells proliferation, migration and invasion. Noni juice also promoted cells apoptosis in A549 cells. Immunoblotting assay showed that the phosphorylation level of AKT, p50, and STAT3 proteins was inhibited to different extents after noni juice treatment. The in vivo studies showed that noni juice effectively suppressed tumor formation of A549 cells in nude mice. Noni juice treatment inhibited the expression of Ki67, PCNA, and Bcl-2 protein in the tumor; while promoted the expression of caspase-3 protein. Additionally, we also found that noni juice treatment could restrain the activity of AKT/NF- κ B signaling pathway in the tumor tissue. CONCLUSION: Noni juice inhibited the proliferation of A549 lung cancer cells, induced apoptosis, and inhibited cell invasion and migration via regulating AKT/NF- κ B signaling pathway.

Matrine Promotes Human Myeloid Leukemia Cells Apoptosis Through Warburg Effect Mediated by Hexokinase 2.

Matrine, an alkaloid compound isolated from the medicinal plant Sophora flavescens, inhibits many types of cancer proliferation. However, the precise mechanism of the matrine antihuman chronic myeloid leukemia remains unclear. In this study, we showed that matrine significantly inhibited the cell proliferation and induced apoptosis by regulating Warburg effect through controlling hexokinases 2 (HK2) expression in myeloid leukemia cells. Interestingly, matrine inhibited the expression of HK2 mediated by reduction in c-Myc binding to HK2 gene intron and led to downregulation of HK2, which upregulated proapoptotic protein Bad and then induced apoptosis. We further demonstrated that matrine could synergize with lonidamine, an inhibitor of HK2, for the treatment of myeloid leukemia, both in vitro and in vivo. Taken together, our findings reveal that matrine could promote human myeloid leukemia cells apoptosis via regulating Warburg effect by controlling HK2.

Matrine inhibits BCR/ABL mediated ERK/MAPK pathway in human leukemia cells.

The BCR/ABL fusion gene and its downstream signaling pathways such as Ras/Raf/MAPK, JAK/STAT3, and PI3K/AKT pathways play important roles in malignant transformation of leukemia, especially chronic myelogenous leukemia (CML). Our previous study showed that matrine, an alkaloid extracted from a Chinese herb radix sophorae, significantly inhibited the proliferation of human CML K562cells, induced cell cycle arrest in G0/G1, and promoted cell apoptosis. In the present study, we investigated the molecular mechanism of matrine in the growth inhibition of leukemia cells using K562 and HL-60 cell lines. RT-PCR and Western blot assay demonstrated that the expression of BCR/ABL in K562 and HL-60 cells was significantly inhibited by matrine treatment. Phosphorylation of MEK1, ERK1/2, and their upstream adaptor molecules Shc and SHP2 were significantly downregulated. The protein and mRNA expression of components of the ERK/MAPK signal pathway, and Bcl-xL, Cyclin D1, and c-Myc, were dramatically reduced. Conversely, the expression of p27, a negative regulator of cell cycle progression, increased after matrine treatment. These results indicated that the inhibition of ERK/MAPK and BCR/ABL signaling pathway was associated with matrine's suppressive effects on the growth of K562 and HL-60 cells. In in vivo study, matrine significantly decreased the mortality rate of tumor-baring mice and suggested that matrine could exert its anti-leukemia effect in vivo.

STAT3 signaling pathway is involved in decitabine induced biological phenotype regulation of acute myeloid leukemia cells.

OBJECTIVE: This study aimed to investigate the role of signal transduction and transcriptional activator STAT3 and relevant signaling pathway in the DAC regulated biological phenotype of AML cells. METHODS: The effect of DAC at different concentrations on the proliferation of HL-60 cells was determined. After DAC treatment for 48 h, the killing capability of NK cells against HL-60 cells and the protein expressions of STAT3, JAK1, JAK2, SOCS-1 and SOCS-3 were evaluated. RESULTS: DAC markedly inhibited the proliferation of HL-60 cells. After the treatment of 48 hr with 0.2, 0.5 and 1.0 mol/L DAC, the HL-60 viability was reduced by 25±13%, 39±8% and 50±7% (P<0.01), respectively, and the early apoptosis rate was increased to 24.77±7.5%, 27.1±4.48% and 30.53±3.93%, respectively (control: 3.11±0.12%, P<0.01). DAC up-regulated the expression of MICA/B, ULBP-1 and ULBP-3 in HL-60 cells, and increased the killing activity of NK cells to HL-60 cells. DAC significantly induced the apoptosis of HL-60 cells and up-regulated the expression of NKG2D ligands in a dose dependent manner. Western blot assay showed the protein expression of STAT3, JAK, JAK2, phosphorylated STAT3, phosphorylated JAK1 and phosphorylated JAK2 decreased, while that of SOCS-1 and SOCS-3 increased in HL-60 cells after DAC treatment. CONCLUSION: In HL-60 cells, DAC can markedly inhibit their proliferation and up-regulate the expression of NKG2D ligands, and DAC also increase the cytotoxicity of NK cells to HL-60 cells, which may be related to the STAT3 related signaling pathway.

Matrine increases NKG2D ligand ULBP2 in K562 cells via inhibiting JAK/STAT3 pathway: a potential mechanism underlying the immunotherapy of matrine in leukemia.

PURPOSE: The study aimed to investigate the role of the JAK/STAT3 pathway in the matrine induced ULBP2 expression on the human chronic myelogenous leukemia K562 cells. METHODS: K562 cells were cultured, and the relevant mRNA expressions were detected. RESULTS: Matrine induced the expression of four NKG2D ligands on K562 cells, of which ULBP2 had the highest increase. After treatment with 0.8 mg/mL matrine for 24 h, the mean fluorescence intensity (MFI) of ULBP2 increased. After matrine treatment, the sensitivity of K562 cells to NK cell-mediated killing increased significantly. After treatment with 0.2, 0.5 and 0.8 mg/ mL matrine, the percentage of K562 cells killed by NK cells was significantly higher than that of untreated cells (29.2%) (P<0.05). Matrine significantly inhibit the protein expression of phosphorylated STAT 3 and JAK2. Matrine markedly inhibited the IL-6 expression of K562 cells, and antagonized the IL-6 mediated STAT3 and JAK2 phosphorylation. In addition, matrine enhanced the inhibitory effect of STAT 3 inhibitor on STAT 3 activity. The silencing of STAT expression and inhibition of STAT3 activity significantly up-regulated the ULPB2 expression. Matrine had no effect on the expression of IL-6R and gp130 on K562 cells, the mRNA expression of IL-6R and gp130 increased slightly and the sgp 130 in cell supernatant significantly increased. CONCLUSIONS: Our findings reveal IL-6 and IL-6 receptor-mediated JAK/STAT3 pathway is involved in the matrine induced up-regulation of NKG2D ligands ULBP2 on K562 cells. Matrine might inhibit IL-6 expression and then suppress the activation of IL-6 receptor-mediated JAK/STAT3 pathway.

STAT3 contributes to NK cell recognition by modulating expression of NKG2D ligands in adriamycin-resistant K562/AO2 cells.

Leukemic cells can survive after chemotherapy by acquisition of multidrug resistance genes, but other phenotypes related to escape from immune recognition remain elusive. Adriamycin-resistant K562/AO2 cells are less susceptible to elimination by NK cells compared with wild type K562 cells due to lower expression of NKG2D ligands. Treatment of K562/AO2 cells with STAT3 inhibitor VII resulted in reduced expression of multidrug resistance gene P-glycoprotein, and up-regulation of NKG2D ligands on K562/AO2 cells. Meanwhile, K562/AO2 cells treated with STAT3 inhibitor proliferated less and were more susceptible to killing by NK cells than untreated K562/AO2 cells. The enhanced cytotoxicity of NK cells against K562/AO2 cells was partly blocked by treatment of NK cells with anti-NKG2D antibodies. These data suggest that STAT3 contributes to NK cell recognition by modulating NKG2D ligands in K562/AO2 cells, which may a mechanism by which cells survive and cause relapse of leukemia.

Matrine regulates immune functions to inhibit the proliferation of leukemic cells.

AIMS: To investigate the roles of matrine in regulating immune functions and its effect on the proliferation of leukemic cells. METHODS: Human leukemia K562, OUN-1, HL-60, U937, K562/AO2 cell lines and primary leukemic cells were used to detect the NKG2D ligands (NKG2DL) expression such as MICA/B, ULBP-1, ULBP-2, ULBP-3, and NK cells receptor NKG2D, CD158a, CD158b were detected by flow cytometry. Cell cytotoxic activity of human NK cells and CIK cells against K562 leukemia cells was detected using CFSE/PI double staining. Pro-inflammatory cytokines and adhesion molecules in K562 or NK cells supernatant after matrine treatment were detected. RESULTS: Matrine could upregulate the expression of NKG2DL on leukemic cell lines, and primary leukemic cells and enhance the NK and CIK cytotoxicity targeted to K562 cells. After matrine treatment, pro-inflammatory cytokines and adhesion molecular such as IL-6, IL-1, IL-2, IL-4, IL-5, GRO and TNF-α in K562 cells supernatant were significantly decreased (P < 0.05). Flow cytometry analysis showed that the NKG2D expression was up-regulated significantly as well as the CD158a and CD158b expression decreased after treatment with different concentration of matrine in a dose-dependent manner in K562 cells. A significant decrease of supernatant concentrations of IL-1α, IL-5, IL-6, IL-10, IFN-γ, GRO and TNF-α in NK cells was also observed after exposure to the matrine. CONCLUSION: Matrine regulates immune functions to inhibit the proliferation of leukemic cells.

[Growth inhibition effect of matrine on K562 cells mediated by IL-6/JAK/STAT3 signaling pathway].

OBJECTIVE: To investigate the molecular mechanism of the growth inhibitory effect of matrine on K562 cells in JAK/STAT3 mediated signal pathway. METHODS: Western blot analyses were performed to investigate the differential expression of JAK2, STAT3, phosphor-STAT3 (Tyr705 & Ser727) and phosphor-JAK2 proteins after matrine treatment in K562 cells with or without human recombinant interleukin 6 (IL-6) pretreatment. The expression of STAT3 response gene products such as Bcl-xL, Cyclin D1 and c-Myc, were investigated by Western blot and quantitative real time RT-PCR (qRT-PCR). Expression of IL-6, a potent upstream activating factor of JAK/STAT3 pathway, was analyzed by both real time qRT-PCR and ELISA. RESUTLS: Western blot revealed that matrine treatment resulted in a strong down-regulation of phosphor-STAT3 both in Tyr705 and Ser727 sites or phosphor-JAK2 proteins expression without significant effects on the total STAT3 and JAK2 proteins. The expression of phosphor-Tyr705 STAT3 and phosphor-Ser727 STAT3 was decreased to 0.370 ± 0.172 in K562 cells treated with 0.5 mg/ml matrine for 48 h, respectively, from 0.690 ± 0.119 and 1.150 ± 0.263 in control cells, accompanied with a dramatical down-regulation of phosphor-JAK2 from 0.670 ± 0.137 to 0.049 ± 0.057 (P<0.05). In addition, it was found that the expression of Bcl-xL, Cyclin D1, c-Myc was decreased both at the transcription and protein level in K562 cells after matrine treatment. Matrine treatment resulted in a significant decrease in the expression level of IL-6 in K562 cells from (35.1 ± 1.93) to (10.74 ± 1.83) and (8.66 ± 1.24) pg/ml at the dose of 0.5 and 0.8 mg/ml, respectively (p<0.05). Matrine treatment could diminish the up-regulation of STAT3, JAK2, phosphor-STAT3 and phosphor-JAK2 protein following pretreatment with IL-6 in K562 cells. CONCLUSION: Matrine exerts its anti-leukemia effect by interfering with the JAK2/STAT3 signaling pathway. The inhibition of IL-6 expression may play a pivotal role in the disruption of JAK/STAT pathway by matrine.

Matrine suppresses cell growth of human chronic myeloid leukemia cells via its inhibition of the interleukin-6/Janus activated kinase/signal transducer and activator of transcription 3 signaling cohort.

Matrine, alkaloid isolated from Sophora flavescens, is known to be pleiotropic by exerting anti-inflammatory, anti-oxidation, as well as anti-cancer effects. However, the precise molecular targets or pathways responsible for its activities still remain unclear. The present study aimed to determine the underlying mechanisms of matrine in inhibiting the chronic myeloid leukemia cells (CML). It was observed that matrine treatment significantly suppressed CML cells proliferation, induced apoptosis and resulted in the accumulation of cells in the G0/G1 phase, accompanied by a significant decrease in Bcl-xL, Cyclin D1, and c-Myc expression. Western blot analyses revealed that matrine treatment resulted in the down-regulation in phospho-STAT3 and phospho-JAK2 without significantly effects on STAT3 and JAK2 protein levels. Matrine significantly reduced the expression of IL-6, a potent upstream activating factor of STAT3. These results strongly suggested the IL-6/JAK/STAT3 pathway play an important role in matrine's anti-leukemia effects in K562 cells.

[Up-regulation of NKG2D ligand ULBP2 by matrine in K562 cells and the underlying molecular mechanisms].

OBJECTIVE: To probe matrine acting on natural killer cell (NK) activating receptor NKG2D ligands expression in CML cell line K562 and its underlying molecular mechanism. METHODS: The expression of NKG2D ligands (major histocompatibility complex class I chain-related molecule A or B (MICA/B), UL16-binding proteins (ULBP) 1, 2, and 3 on K562 cells were analyzed before and after treated with matrine by FCM. The cytotoxic sensitivity of K562 to NK cell was detected by FCM after CFSE staining at different effect-to-target (E/T) cell ratios. The expression of signal transduction and transcriptional activator 3 (STAT3) protein as well as phosphorylated STAT3 (p-STAT3) were detected by western blot. RESULTS: After treatment with matrine, ULBP1 and ULBP2 expression, especially ULBP2 on K562 cells significantly increased, with mean fluorescence intensity (MFI) increasing to 615 and 1614 by 220 and 615 in the untreated cells, respectively. There was no significant change for MICA or ULBP3 expression. Matrine enhanced the susceptibility of K562 cells to NK-mediated cell lysis. At the ratio of E/T with 5:1, the proportion of the killed K562 cells increased to 32.8%, 38.1% and 40.5%, respectively (after 0.2, 0.5 and 0.8 mg/ml matrine treatment) by 29.2% in the untreated cells. The phosphorylated STAT3 protein, but not STAT3 protein, was significantly inhibited by matrine treatment in K562 cells. CONCLUSION: Matrine induced the expression of NKG2D ligands in K562cells and enhanced the cytotoxicity of NK cells against K562, which was closely related to the inhibition of STAT3 activity in K562 cell.

[Roles of NKG2D in cytokine-induced killer (CIK) against hematological malignant cells lines].

This study was purposed to investigate the CIK cell cytotoxicity to hematological malignant cell lines by interaction NKG2D receptors and corresponding ligands. The CIK cells was expanded from healthy individual with interferon (IFN)γ, CD3 monoclonal antibodies (mAb) and interleukin-2 (IL-2). The subset of lymphocyte and the expression of NK cell receptors on CIK cells was detected by flow cytometry; NKG2D ligand expression on hematological malignant cell lines was also analyzed by flow cytometry, the calcein acetoxymethyl ester (CAM) was used for labeling target cells, then the cytotoxicity of CIK cells to hematological malignant cell lines was detected by flow cytometry. The results showed that most of CIK cells expressed CD3 (97.85 ± 1.95%) , CD3(+)CD8(+) cells and CD3(+)CD56(+) cells increased significantly as compared with un-cultured cells (P < 0.001;P = 0.033). About 86% CIK cells expressed NKG2D receptor but no other NK receptors such as CD158a, CD158b and NCR. Different levels of NKG2D ligands were detected in hematological malignant cell lines U266, K562 and Daudi. CIK cells showed high cytotoxicity to these three different cell lines, and this cytotoxicity was partially blocked by treating CIK cells with anti-NKG2D antibody (U266 52.67 ± 4.63% vs 32.67 ± 4.81%, P = 0.008;K562 71.67 ± 4.91% vs 50.33 ± 4.91%, P = 0.007;Daudi 68.67 ± 5.04 vs 52.67 ± 2.60%, P = 0.024) . It is concluded that most of CIK cells express NKG2D receptor, interaction of NKG2D-NKG2D ligands may be one of the mechanisms, by which CIK cells kill hematological malignant cells.

[Effects of matrine on the expression of NKG2D ligands in leukemia cells].

This study was aimed to analyze the expression of NKG2D ligands in human leukemic cells and to investigate the effects of matrine on NKG2D ligand expression. The expressions of NKG2D ligand MICA/B, ULBP1-3 in several human leukemia cell lines (K562, OUN-1, U937 and K562/AO2), as well as primary leukemic cells isolated from malignant leukemia patients were analyzed by flow cytometry. After treatment with different doses of matrine, the expression level of NKG2D ligands in these leukemic cells was detected by FCM. The results indicated that NKG2D ligand expression was detected in both the leukemia cell lines and primary malignant leukemic cells. Generally, the expression of ULBP was high or obviously higher than that of MICA/B in leukemia cell lines and primary leukemic cells. The expression pattern of NKG2D ligands was different among these cells, possibly due to the different types of leukemia. Not all the expression of NKG2D ligands was upregulated after matrine treatment. Much higher expressions of ULBP2 and ULBP3 were found in K562 cells, compared to the other cell lines, which partly contributes to the higher sensitivity of K562 cells to NK cytotoxicity as target cells. It is concluded that there is universal expression of NKG2D ligand in leukemia cells. The high ULBP expression is prevalent in human leukemia cells. Matrine has the potential to induce the expression of NKG2D ligands in leukemia cells.

[Enhanced cytotoxicity against leukemia cells of natural Killer cells from cord blood after expansion in vitro].

OBJECTIVE: To investigate the enhanced cytotoxicity against leukemia cells of natural Killer (NK) cells from cord blood (CB) after expansion in vitro. METHODS: NK cells was expanded on a layer of trophoblast cells with irradiated K562-mb15-41BBL cell line for 21 days. The levels of receptors on NK cells were detected by flow cytometry. Cytotoxicity of expanded NK cells against leukemia cells and specific ligand of immunoglobulin like(Ig- liKe)receptors were assessed using 51Cr released assay. RESULTS: There were no differences of inhibitory receptors expression between fresh NK cells and expanded NK cells [CD158a:(16.77±11.65)% vs(14.37±11.12)%, P>0.05; CD158b: (42.48±18.11)% vs (40.92±19.02)%, P>0.05; NKG2A: (70.20±18.43)% vs (78.90±13.69)%, P>0.05], but higher activated receptors expression on expanded NK cells [NKp30: (54.10±13.27)% vs (4.14±2.05)%, P<0.05; NKp44: (72.10±17.30)% vs (0.52±1.16)%, P<0.05; NKp46: (80.63±14.01)% vs (44.19±6.19)%, P<0.05; NKG2D: (97.50±2.55)% vs (72.25±14.35)%, P<0.05]. Expanded NK cells showed higher cytotoxicity against leuKemia cell lines than fresh NK cells [K562: (74.3±3.6)% vs (55.3±4.2)%, P<0.05; Raji: (60.6±5.0)% vs (12.0±3.6)%, P<0.05]. CD158a⁻ CD158b⁻ NK cells had higher cytotoxicity on four types of target cells, but CD158a⁺CD158b⁻ CB-NK cell had lower cytotoxicity on 221-Cw4 and 221-Cw3Cw4 cells. CD158a⁻ CD158b⁺ CB- NK cells had lower cytotoxicity on 221-Cw3 and 221-Cw3Cw4, but CD158a⁺CD158b⁺ CB-NK cells had higher cytotoxicity on 721- 221 cells. CONCLUSION: Expression of activated receptors of expanded NK cells were up-regulated, but no changes of inhibitory receptors. Expanded NK cells showed high cytotoxicity against leukemia cells and kept the specificity of ligand of Ig-like receptors, which could be beneficial to cell-therapy for tumor.

[NKG2D-mediated natural killer cell cytotoxicity against myeloid leukemia cells OUN-1].

OBJECTIVE: To investigate NK cell cytotoxicity to leukemic cell by NKG2D receptors and NKG2D ligands interaction upregulated by hydroxyurea (HU). METHODS: Leukemic cell lines OUN-1 and primary leukemic cells were cultured for 24 hours in the presence of HU, then the NKG2D ligands expressions were analyzed by flow cytometry (FCM). Isolated NK cells from healthy individual cultured for 72 hours in presence of IL-2 were used as effect cell, and leukemic cell line OUN-1 treated with HU was used as target cell, NK cell cytotoxicity against leukemic cell line was assessed using chromium-51 release assay. RESULTS: Leukemic cell lines showed upregulation of MIC A/B (MFI: 8.9 ± 0.9 vs 23.5 ± 3.4, P = 0.01) and ULBP2 (MFI: 14.5 ± 0.6 vs 33.5 ± 4.8, P = 0.03) following incubation with HU. HU also upregulated the NKG2DLs on primary leukemia cells from patients with acute myeloid leukemia. Treatment of OUN-1 with HU significantly increased the cytotoxicity of NK cells isolated from healthy individual \[(62.0 ± 5.6)% vs (76.0 ± 5.3)%, P = 0.02\], and the enhancing effect of HU was partly blocked by anti-NKG2D Abs \[(76.0 ± 5.3)% vs (46.0 ± 4.5)%, P = 0.00\]. CONCLUSION: HU selectively upregulated NKG2D ligand expression on leukemic cell lines, and enhanced NK cell cytotoxicity against leukemic cells through NKG2D receptors and NKG2D ligands interaction.

Role of NKG2D in cytokine-induced killer cells against multiple myeloma cells.

The cytokine-induced killer cells (CIK) have been reported to have potent cytotoxicity against a variety of tumor cells including multiple myleoma (MM) cells. The mechanisms that CIK cell recognizing MM cells remain unknown. Recent studies indicated that the interaction between NKG2D receptor and NKG2D ligands plays an important role in inducing cytotoxicity against various target cells by natural killer cells (NK). We suspect whether NKG2D receptor and NKG2D ligands interaction is also responsible for the killing of MM cells by CIK as the same way did NK cells. We expanded CIK cells from healthy controls with interferon (IFN)-γ, CD3 monoclonal antibodies (mAb) and interleukin-2 (IL-2), and checked expression of NK cell receptors on CIK cells by flow cytometry. About 86% bulk CIK cells expressed NKG2D receptor but not other NK receptors, such as CD158a, CD158b and NCRs. We analyzed NKG2D ligands expression in MM patients by flow cytometry, primary plasma cells from 8 out of 13 (62%) MM patients expressed different levels of ULBPs or MICA/B on the cell surface. Interestingly, when stimulated with MM cell line U266 that expressed some levels of MICA/B, only NKG2D expressing CIK cells released IFN-γ. CIK cells showed cytotoxicity against NKG2D ligands expressing U266 and primary MM cells, and the cytotoxicity was partially blocked by treating CIK with anti-NKG2D antibody. We conclude that NKG2D-NKG2D ligand interaction may be one of the mechanisms by which CIK cells kill MM cells.

Heme oxygenase-1 is induced by thyroid hormone and involved in thyroid hormone preconditioning-induced protection against renal warm ischemia in rat.

Thyroid hormone pretreatment was indicated to increase tissue tolerance to ischemia-reperfusion injury (IRI) in various organs, but the underlying molecular mechanisms remains largely unknown. Induction of heme oxygenase-1 (HO-1) protects organs against IRI. The present study investigated the effect of thyroid hormone on HO-1 expression and the possible relation between HO-1 and the thyroid hormone induced renal protection. T(3) administration in rat kidneys induced HO-1 expression in a time-dependent and dose-dependent way, and its expression was accompanied with significant depletion of reduced glutathione and increase in malondialdehyde content, showing a moderate oxidative stress that turns to normal level 48 h after drug injection. Thyroid hormone pretreatment (10 µg/100g body weight) 48 h before IR procedure significantly decreased serum creatinine and urea nitrogen and preserved renal histology, with significant reduction of parameters about oxidative stress and over-expression of HO-1 compared with that of IR group. In conclusion, T(3) administration involving oxidative stress in kidney exerts significant enhancement of HO-1 expression which may, at least in part, account for the renal preconditioning induced by T(3).