Anti-tumor activity of 5-aminoimidazole-4-carboxamide riboside with AMPK-independent cell death in human adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T cell leukemia/lymphoma caused by human T-cell lymphotropic virus type I (HTLV-1). Acadesine or 5-aminoimidazole-4-carboxamide riboside (AICAR) is an AMP-activated protein kinase (AMPK) activator that was recently shown to have tumor suppressive effects on B cell chronic lymphocytic leukemia, but not ATL. This study evaluated the cytotoxic effects of AICAR on ATL-related cell lines and its anti-tumor activity. Here, we demonstrated that AICAR induced cell death via apoptosis and the mitochondrial membrane depolarization of ATL-related cell lines (S1T, MT-1, and MT-2) but not non-HTLV-1-infected Jurkat cells. However, AICAR did not increase the phosphorylation levels of AMPKα. In addition, AICAR increased the expression of the death receptors (DR) DR4 and DR5, and necroptosis-related proteins including phosphorylated receptor-interacting protein family members and the mixed lineage kinase domain-like protein. Interestingly, HTLV-1 Tax, an HTLV-1-encoded oncogenic factor, did not affect AICAR-induced apoptosis. Furthermore, AICAR inhibited the growth of human ATL tumor xenografts in NOD/SCID/gamma mice in vivo. Together, these results suggest that AICAR induces AMPK-independent cell death in ATL-related cell lines and has anti-tumor activity, indicating that it might be a therapeutic agent for ATL.

CDK9 Inhibitor Induces Apoptosis, Autophagy, and Suppression of Tumor Growth in Adult T-Cell Leukemia/Lymphoma.

Adult T-cell leukemia/lymphoma (ATL) is a hematopoietic malignancy with a poor prognosis that develops in approximately 5% of human T-cell leukemia virus type 1 (HTLV-1) carriers. Cyclin-dependent kinase 9 (CDK9), together with Cyclin T, forms a transcription elongation factor, positive transcription elongation factor b (P-TEFb). P-TEFb promotes transcriptional elongation by phosphorylating the second serine (Ser2) of the seven amino acid repeat sequence in the C-terminal domain of RNA polymerase II (RNAP II). CDK9 inhibitors suppress cell proliferation by inducing apoptosis in chronic lymphocytic leukemia and breast cancer but there are no reports on autophagy of CDK9 inhibitors. Here, we investigated the effect of LY2857785, a novel CDK9 selective inhibitor, on cell death in ATL-related cell lines in vitro, freshly isolated cells from ATL patients ex vivo, and on ATL tumor xenografts in NOD/SCID mice in vivo. LY2857785 significantly reduced cell viability and induced apoptosis, as shown by annexin V-positive cells, cleaved poly(ADP-ribose) polymerase (PARP), and cleaved caspase-3, and suppressed the levels of anti-apoptotic protein myeloid cell leukemia-1 (MCL-1). LY2857785 decreased RNAP II Ser2 phosphorylation and downstream c-Myc protein levels. Interestingly, LY2857785 also increased microtubule-associated proteins 1A/1B light chain 3B (LC3)-II binding to autophagosome membranes. Furthermore, LY2857785 decreased the viability of freshly isolated ATL cells and induced apoptosis. Finally, LY2857785 significantly decreased the growth of ATL tumor xenografts. These results suggest that LY2857785 induces cell death of ATL cells by MCL-1-dependent apoptosis and autophagy and has anti-tumor activity.

SRT1720 induces SIRT1-independent cell death in adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATL) develops after a long period of human T-cell leukemia virus (HTLV)-1 infection and is associated with host aging in addition to genetic abnormalities in HTLV-1 infected cells. SIRT1 is a histone deacetylase involved in cell cycle and apoptosis. We previously showed the high expression of SIRT1 protein in peripheral blood mononuclear cells from patients with ATL. There have been many reports that SIRT1 inhibitors show tumor-suppressive effects. On the other hand, SIRT1 activator SRT1720 induces the cell death of multiple myeloma and breast cancer cells. However, the effect of SRT1720 on ATL is unknown. This study aimed to evaluate the effect of SRT1720 on cell death in leukemic cell lines in vitro and freshly isolated ATL cells ex vivo and in an ATL in vivo mouse model. SRT1720 reduced cell viability in vitro and ex vivo. Additionally, SRT1720 increased the number of apoptotic cells, as shown by annexin V positive cells, cleaved poly (ADP-ribose) polymerase 1, cleaved caspase-3, and fragmented DNA. SRT1720 also induced mitochondrial outer membrane permeabilization with the generation of mitochondrial reactive oxygen species and autophagy. However, SIRT1 knockdown did not attenuate SRT1720-induced cell death in leukemic cell lines. Finally, SRT1720 treatment decreased the growth of human ATL tumor xenografts in immunodeficient mice. Our study shows that while SRT1720 does not target SIRT1, it induces cell death in ATL cells via apoptosis and autophagy and has antitumor activity.

High expression of NAMPT in adult T-cell leukemia/lymphoma and anti-tumor activity of a NAMPT inhibitor.

Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature T lymphocytes induced by human T-cell leukemia virus-1 and has a poor outcome. New molecular targets for the prevention and treatment of ATL are needed urgently. We previously reported high expression of Sirtuin 1, a nicotinamide adenine dinucleotide (NAD+)-dependent histone/protein deacetylase, in primary acute-type ATL cells. NAD+ biosynthesis via nicotinamide phosphoribosyltransferase (NAMPT) modulates Sirtuin 1 activity. Here, we examined the expression and effects of inhibiting NAMPT, a rate-limiting enzyme in NAD+ biosynthesis, in ATL cells. We found that peripheral blood mononuclear cells from patients with acute-type ATL expressed significantly higher levels of NAMPT protein than cells from healthy subjects. FK866, a NAMPT inhibitor, induced apoptosis of freshly isolated ATL cells ex vivo and HTLV-1-infected T-cell lines in vitro, which was accompanied by activation of caspases, DNA fragmentation, and disruption of mitochondrial transmembrane potential. However, a pan-caspase inhibitor failed to prevent this FK866-induced cell death, while FK866 increased the caspase-independent cell death mediator endonuclease G. Intriguingly, FK866 also activated autophagy, as demonstrated by increases in protein levels of autophagosome marker LC3-II. Thus, FK866 simultaneously activated apoptosis and autophagy. Finally, FK866 treatment markedly decreased the growth of human ATL tumor xenografts in immunodeficient mice. We showed that NAMPT is highly expressed in primary ATL cells ex vivo, and that FK866 induces autophagy and caspase-dependent and -independent cell death pathways in vitro and has an anti-tumor activity in vivo. These results suggest a novel therapeutic strategy for patients with this fatal disease.

The small molecule STF-62247 induces apoptotic and autophagic cell death in leukemic cells.

Adult T cell leukemia/lymphoma (ATL) is an aggressive malignant T cell disease caused by human T cell leukemia virus-I (HTLV-1). Treatment outcomes for aggressive subtypes of ATL remain poor, with little improvement in overall survival since HTLV-1 was discovered. Therefore, new therapeutic strategies for ATL are required. STF-62247 induces autophagy and selectively kills renal cell carcinoma without apoptotic cell death. Here, we demonstrate that STF-62247 reduced cell viability and resulted in autophagosome accumulation and autophagy in leukemic cell lines (S1T, MT-2, and Jurkat). Interestingly, STF-62247 induced apoptosis in HTLV-1-infected cell lines (S1T and MT-2), as indicated by DNA fragmentation and caspase activation, but not in non-HTLV-1-infected Jurkat cells; a caspase inhibitor did not prevent this caspase-associated cell death. STF-62247 also increased nuclear endonuclease G levels. Furthermore, STF-62247 reduced cell viability and increased the number of apoptotic cells in peripheral blood mononuclear cells collected from patients with acute ATL, which has a poor prognosis. Therefore, STF-62247 may have novel therapeutic potential for ATL. This is the first evidence to demonstrate the cell growth-inhibitory effect of an autophagy inducer by caspase-dependent apoptosis and caspase-independent cell death via autophagy and endonuclease G in leukemic cells.

Dimethylthiourea ameliorates carbon tetrachloride-induced acute liver injury in ovariectomized mice.

AIMS: In order to clarify hepato-protective actions of estrogen, we examined the progress of carbon tetrachloride (CCl4)-induced acute liver injury (ALI) in sham and ovariectomized (ovx) mice and the effects of dimethylthiourea (DMTU), a hydroxyl radical scavenger, and meloxicam (Melo), a selective cox-2 inhibitor, on the development of CCl4-induced ALI. MAIN METHODS: Female C57BL/6 J mice weighing 15-20 g were performed sham or ovx operation at 8 weeks of age. Blood and liver samples were collected 15 and 24 h after CCl4 administration. Sham and ovx mice were given DMTU, Melo or saline intraperitoneally 30 min before CCl4 or corn oil administration. KEY FINDINGS: ALT levels in ovx mice were significantly increased compared to those in sham mice. DMTU reduced ALT levels in ovx mice to the same levels as those in sham mice after CCl4 injection. CCl4 upregulated TNF-α, IL-6, cox-2 and iNOS expression in ovx mice compared to the levels in sham mice. DMTU significantly reduced cox-2 and iNOS expression levels upregulated by CCl4 in ovx mice. However, pretreatment with Melo had no effects on ALT levels and the gene expression levels of TNF-α, IL-6 and HO-1 in either sham or ovx mice, indicating that cox-2 may not participate in increase of CCl4-induced ALI caused by estrogen deficiency. SIGNIFICANCE: Ovariectomy accelerated the development of CCl4-induced acute liver injury, and DMTU reduced liver injury. These results suggest that estrogen may act as an antioxidant in the development CCl4-induced acute liver injury.

Rapid increase of 'brain-type' transferrin in cerebrospinal fluid after shunt surgery for idiopathic normal pressure hydrocephalus: a prognosis marker for cognitive recovery.

Idiopathic normal pressure hydrocephalus (iNPH) is a dementia-inducing disorder. Primary cause of iNPH is speculated to be a reduction of cerebrospinal fluid (CSF) absorption, which secondarily induces hydrocephalus, compression of brain, and reduction of CSF production. Patients are treated by surgically inserting a shunt to deliver excess CSF to the abdominal cavity. The prognosis for cognitive improvement after shunt surgery has been difficult to predict. We therefore investigated various CSF proteins, hoping to find a biomarker predictive of cognitive performance one to two years after shunt surgery. CSF proteins of 34 iNPH and 15 non-iNPH patients were analysed by Western blotting, revealing two glycan isoforms of transferrin (Tf); 'brain-type' Tf with N-acetylglucosaminylated glycans and 'serum-type' Tf with α2, 6-sialylated glycans. Brain-type Tf levels decreased in iNPH but rapidly returned to normal levels within 1-3 months after shunt surgery. This change was positively correlated with recovery from dementia, per Mini-Mental State Examination and Frontal Assessment Battery scores at 11.8 ± 7.7 months post-operation, suggesting that brain-type Tf is a prognostic marker for recovery from dementia after shunt surgery for iNPH. Histochemical staining with anti-Tf antibody and an N-acetylglucosamine-binding lectin suggests that brain-type Tf is secreted from choroid plexus, CSF-producing tissue.

Apocynin reduced doxycycline-induced acute liver injury in ovariectomized mice.

To determine the physiological role of estrogen in the development of liver injury, we examined the sensitivities of sham and ovariectomy (ovx) mice against doxycycline (DOXY)-induced acute liver injury. Ovx or sham operation was performed in C57BL/6J wild-type female mice of eight weeks of age. Sham mice and ovx mice were treated with DOXY (240 mg/kg ip) 8 weeks after the operation, 30 min after apocynin (5 mg/kg) or saline administration. Blood and liver samples were obtained at 3 and 6 h after DOXY administration. Liver dysfunction occurred soon after DOXY administration and became more severe in ovx mice than in sham mice. At early phase after DOXY injection, TNF-α and iNOS inductions upregulated almost the same levels in sham and ovx mice. On the other hand, expression levels of IL-6, IL-10, c-fos, cox-2 and HO-1, downstream genes of TNF-α, were significantly increased in ovx mice compared to those in sham mice, correlated with liver dysfunction. In addition, apocynin, a NADPH oxidase (Nox) inhibitor, totally improved DOXY-induced liver injury in both sham and ovx mice, indicating that reactive oxygen species generated through Nox activation by DOXY are responsible for development of acute liver injury.

Oxidative stress may be involved in distant organ failure in tourniquet shock model mice.

Crush syndrome is characterized by prolonged shock resulting from extensive muscle damage and multiple organ failure. However, the pathogenesis of multiple organ failure has not yet been completely elucidated. Therefore, we investigated the molecular biological and histopathological aspects of distant organ injury in crush syndrome by using tourniquet shock model mice. DNA microarray analysis of the soleus muscle showed an increase in the mRNA levels of Cox-2, Hsp70, c-fos, and IL-6, at 3h after ischemia/reperfusion injury at the lower extremity. In vivo staining with hematoxylin and eosin (HE) showed edema and degeneration in the soleus muscle, but no change in the distant organs. Immunohistological staining of the HSP70 protein revealed nuclear translocation in the soleus muscle, kidney, liver, and lung. The c-fos mRNA levels were elevated in the soleus muscle, kidney, and liver, displaying nuclear translocation of c-FOS protein. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) analysis suggested the involvement of apoptosis in ischemia/reperfusion injury in the soleus muscle. Apoptotic cells were not found in greater quantities in the kidney. Oxidative stress, as determined using a free radical elective evaluator (d-ROM test), markedly increased after ischemia/reperfusion injury. Therefore, examination of immunohistological changes and determination of oxidative stress are proposed to be useful in evaluating the extent of tourniquet shock, even before changes are observed by HE staining.

Interleukin-6 modulates oxidative stress produced during the development of cisplatin nephrotoxicity.

AIMS: We reported that interleukin-6 (IL-6) plays a protective role in the development of cisplatin-induced acute renal failure (ARF) through upregulation of anti-oxidative stress factors. In this study, we examined the effects of dimethylthiourea (DMTU), a hydroxyl radical scavenger, on the development of cisplatin-induced ARF in wild-type (WT) and IL-6(-/-) mice to determine how IL-6 contributes to modulation of oxidative stress caused by cisplatin. MAIN METHODS: WT and IL-6(-/-) male mice were given either cisplatin (30 mg/kg) or saline intraperitoneally. DMTU (100mg/kg) or saline was given 30 min before cisplatin or saline administration. Blood and kidney samples were collected on days 1 and 3 after cisplatin administration. KEY FINDINGS: In WT mice, DMTU markedly improved cisplatin-induced renal dysfunction and survival rate. DMTU reduced the expression levels of TNF-α, Bax and c-fos and increased the expression levels of IL-6, Bcl-xL and Nrf2 in WT mice. Reduced reactive oxygen species (ROS) by DMTU resulted in increases of IL-6, anti-apoptosis and anti-oxidant gene expression levels. In IL-6(-/-) mice, DMTU also improved cisplatin-induced renal dysfunction and reduced expression levels of TNF-α, Bax and c-fos, but not Bcl-xL and Nrf2. Since Nrf2 induces IL-6 expression, IL-6 and Nrf2 may influence each other during anti-oxidant responses. The basal level of HO-1 in IL-6(-/-) mice was higher than that in WT mice. SIGNIFICANCE: In IL-6(-/-) mice, overproduction of ROS by cisplatin results in upregulation of HO-1 expression in order to eliminate oxidative stress. IL-6 mediates the generation and elimination of ROS during cisplatin-induced ARF.

Interleukin-6 plays a protective role in development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors.

AIMS: Cisplatin, a major chemotherapeutic agent, accumulates in proximal tubules of the kidneys and causes acute renal failure dose-dependently. We previously reported that cisplatin induced more severe renal dysfunction in interleukin-6 (IL-6) knockout (IL-6(-/-)) mice than in wild-type (WT) mice. Expression of a pro-apoptotic protein was significantly increased with cisplatin in IL-6(-/-) mice compared to that in WT mice. IL-6, locally expressed in renal tubular cells after cisplatin administration, prevents the development of renal dysfunction at an early stage. In the present study, we focused on downstream signals of IL-6 and oxidative stress induced by cisplatin in order to evaluate the protective role of IL-6 in the development of acute renal failure. MAIN METHODS: WT and IL-6(-/-) mice were given either cisplatin (30 mg/kg) or saline intraperitoneally. Blood and kidney samples were collected at 24h and 72 h after cisplatin administration. The changes in expression of 4-hydroxy-2-nonenal protein (4-HNE, oxidative stress marker) and cyclooxygenase-2 (cox-2), activities of superoxide dismutases and caspase-3, and phosphorylation of extracellular signal-regulated kinase (ERK) were examined. KEY FINDINGS: Cisplatin increased the expression of 4-HNE and cox-2, and phosphorylation of ERK in IL-6(-/-) mice than in WT mice. On the other hand, activity of superoxide dismutase, an anti-oxidative enzyme, was significantly decreased in the kidney obtained from IL-6(-/-) mice after cisplatin administration. SIGNIFICANCE: Our findings suggest that IL-6 plays a protective role in the development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors.

Comparison of renal dysfunction in wild-type, IL-6 KO and iNOS KO mice hind limb tourniquet-reperfusion model.

The release of a tourniquet after hind limb ischemia results in vital organ injury, which progresses to multiple organ failure with a high mortality rate. Many events are involved in ischemia-reperfusion (I/R) injury. The purpose of this study was to determine how IL-6 or iNOS is involved in I/R injury using IL-6 knockout (KO) and iNOS KO mice. Male C57BL/6J wild-type (WT), IL-6 knockout (KO) and iNOS KO mice were anesthetized with pentobarbital, and rubber bands were fastened to the inguinal region of both hind limbs for 3h. Blood and kidney samples were obtained before reperfusion and at 1, 2, 3, and 12h after reperfusion. For the control group, mice were kept for 6h under an anesthetized condition without rubber bands. Blood gases and biochemical parameters were analyzed by i-STAT300F. Real-time PCR analyses were performed to examine the expression levels of IL-6 and iNOS mRNA in kidneys. Metabolic acidosis, hemoconcentration and renal dysfunction were significantly developed after reperfusion regardless of mouse genotype, and progression of this condition was earlier in IL-6 KO and iNOS KO mice than in WT mice. The expression level of kidney IL-6 mRNA increased and that of iNOS mRNA decreased after reperfusion. It is possible that late decrease recovery of iNOS mRNA expression in IL-6 KO mice and early progress of IL-6 mRNA expression in iNOS KO mice after reperfusion induce renal dysfunction.

A hind limb tourniquet induces interleukin-6 expression in a rat dorsal root ganglion.

We investigated the mRNA levels of interleukin-6-related genes in a rat dorsal root ganglion after application of a tourniquet to a hind limb in order to identify the molecules that are induced immediately after peripheral nerve injury at the early stage. Induction of interleukin-6 and upregulation of glycoprotein 130 mRNA expressions were observed in the ipsilateral dorsal root ganglion at 4 h after tourniquet application. Interleukin-6 protein was detected in small-sized and medium-sized dorsal root ganglion cells by immunohistochemical analysis. The induction of interleukin-6 expression is likely to play a role in the protection of injured neurons perhaps related to growth of their axons. Glycoprotein 130 might also account for the inhibitory effects following nerve injury.