LIGHT (TNFSF14) promotes the differentiation of human bone marrow-derived mesenchymal stem cells into functional hepatocyte-like cells.

Liver transplantation is the most effective treatment option for patients with acute or chronic liver failure. However, the applicability and effectiveness of this modality are often limited by a shortage of donors, surgical complications, high medical costs, and the need for continuing immunosuppressive therapy. An alternative approach is liver cell transplantation. LIGHT (a member of the tumor necrosis factor superfamily) could be a promising candidate for promoting the differentiation of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) into hepatocyte-like cells. In this study, we investigated the effect of LIGHT on hBM-MSC differentiation into hepatocyte-like cells. Our previous results showed that LIGHT receptor lymphotoxin-ß receptor (LTßR) is constitutively expressed on the surface of hBM-MSCs. Upon treatment with recombinant human LIGHT (rhLIGHT), the phenotype of hBM-MSCs changed to round or polygonal cells. In addition, the cells exhibited high levels of hepatocyte-specific markers, including albumin, cytokeratin-18 (CK-18), CK-19, cytochrome P450 family 1 subfamily A member 1 (CYP1A1), CYP1A2, CYP3A4, SRY-box transcription factor 17 (SOX17), and forkhead box A2 (FOXA2). These results indicate that rhLIGHT enhances the differentiation of hBM-MSCs into functional hepatocyte-like cells. Furthermore, rhLIGHT-induced hepatocyte-like cells showed a higher ability to store glycogen and uptake indocyanine green compared with control cells, indicating functional progression. Additionally, treatment with rhLIGHT increased the number, viability, and proliferation of cells by inducing the S/G2/M phase and upregulating the expression of various cyclin and cyclin dependent kinase (CDK) proteins. We also found that the hepatogenic differentiation of hBM-MSCs induced by rhLIGHT was mediated by the activation of signal transducer and activator of transcription 3 (STAT3) and STAT5 pathways. Overall, our findings suggest that LIGHT plays an essential role in promoting the hepatogenic differentiation of hBM-MSCs. Hence, LIGHT may be a valuable factor for stem cell therapy.

The soluble VCAM-1 level is a potential biomarker predicting severe acute graft versus host disease after allogeneic hematopoietic cell transplantation.

BACKGROUND: Severe graft versus host disease (GVHD) is the main reason for non-relapse mortality following allogeneic hematopoietic cell transplantation (HCT). We investigated the serum protein profiles of patients who had undergone HCT to identify predictive biomarkers of severe acute GVHD (aGVHD). METHODS: Serum samples were collected for 30 patients from day - 7 to day + 14 of HCT. The serum levels of plasma beta2-microglobulin (ß2-MG), soluble vascular cell adhesion molecule-1 (sVCAM-1), platelet factor 4, and TNFSF-14 were measured by ELISA as potential biomarkers following 310 cytokine profiling array. RESULTS: The median age of the study patients was 53.5 years (range, 19-69). All grade and grade 2-4 aGVHD developed in 21 (70.0%) and 17 (56.7%) patients, respectively. Compared with their baseline levels on day - 7, ß2-MG and sVCAM-1 were significantly increased on day + 14 of the HCT procedure (P = 0.028 and P < 0.001, respectively). Patients with a grade 2-4 severe aGVHD showed a significantly higher sVCAM-1 level at baseline (day-7) and at day + 14, compared with the other group with a grade 1 aGVHD or no aGVHD (P = 0.028 and P = 0.035, respectively). CONCLUSION: Higher sVCAM- levels at baseline and on day + 14 in HCT patients could be a significant predictive biomarker of severe aGVHD.

Radotinib inhibits multiple myeloma cell proliferation via suppression of STAT3 signaling.

Multiple myeloma (MM) is a hematological cancer causing from accumulated abnormal plasma cells. STAT3 overexpression in MM appears to be mediated by a variety of factors, and it may be associated with an adverse prognosis and play a role in microenvironment-dependent treatment resistance. Unfortunately, MM remains an incurable disease, as relapse is very common. Therefore, there is urgent need to develop new treatment options for MM. Radotinib is a novel anti-cancer drug, currently approved in South Korea for the treatment of chronic myeloid leukemia patients. It is an oral, multitargeted inhibitor of receptor tyrosine kinases, including BCR-ABL, c-KIT, PDGFR, and Src family kinases. However, little is known about the effects of radotinib on multiple myeloma cells. However, little is known about the effects of radotinib on multiple myeloma cells. But even tinip almost not known about the impact of multiple myeloma cells. Moreover, nothing is known about how it affects STAT3 and JAK2. In this study, we analyzed the effect of radotinib on multiple myeloma cells. Herein, Moreover, nothing is known about how it. Moreover, not all is known about how the affects STAT3 and JAK2. We investigated the effect of radotinib on the STAT3 signaling pathway in MM cells, including several MM cell lines and mouse models. So we investigated the effect of radotinib on MM cells, including several MM cell lines and mouse models. Interestingly, radotinib induced apoptosis, and inhibited cell proliferation in MM cells including RPMI-8226, MM.1S, U266B1, and IM-9 cells. Moreover, radotinib treatment significantly increased the number Annexin V-positive cells and G0/G1-phase cells. In addition, radotinib treatment in various MM cells strongly suppressed the activity and expression of STAT3 and JAK2 proteins. We also observed that diverse proteins related to the STAT3 signaling pathway, including c-Myc, Bcl-xL, Mcl-1, cyclin D1 and cyclin D3, were powerfully inhibited by radotinib treatment in MM cells. Furthermore, radotinib significantly suppressed MM cell growth in a xenograft animal model using IM-9 cells. In conclusion, radotinib may play an important role as a candidate agent for MM treatment.

The c-Abl inhibitor, radotinib induces apoptosis in multiple myeloma cells via mitochondrial-dependent pathway.

Multiple myeloma (MM) is a hematological cancer resulting from accumulated abnormal plasma cells. Unfortunately, MM remains an incurable disease, as relapse is very common. Therefore, there is urgent need to develop new treatment options for MM. Radotinib is a novel anti-cancer drug, currently approved in South Korea for the treatment of chronic myeloid leukemia patients. Its mechanism of action involves inhibition of the tyrosine kinase Bcr-Abl and the platelet-derived growth factor receptor. Generally, the mechanism of inhibition of non-receptor tyrosine kinase c-Abl has played an essential role in the inhibition of cancer progression. However, little is known regarding the effects of the c-Abl inhibitor, radotinib on MM cells. In this study, we analyzed the effect of radotinib on multiple myeloma cells. Interestingly, radotinib caused apoptosis in MM cells including RPMI-8226, MM.1S, and IM-9 cells, even in the absence of c-kit expression in 2 of these lines. Radotinib treatment significantly increased the number Annexin V-positive cells and decreased the mitochondrial membrane potential in MM cells. Additionally, we observed that cytochrome C was localized in the cytosol of radotinib-treated MM cells. Moreover, radotinib decreased the expression of Bcl-2 and Bcl-xL, and increased the expression of Bax and Bak in MM cells. Furthermore, radotinib promoted caspase pathway activation by inducing the expression and activity of caspase-3, -7, and -9. Expression of cleaved PARP-1 was also increased by radotinib treatment in various MM cells. In addition, radotinib significantly suppressed MM cell growth in a xenograft animal model using RPMI-8226 cells, and killed ex vivo myeloma cells from patients. In conclusion, radotinib may play an important role as a candidate agent or chemosensitizer for the treatment of MM.

LIGHT (TNFSF14) enhances osteogenesis of human bone marrow-derived mesenchymal stem cells.

Osteoporosis is a progressive systemic skeletal disease associated with decreased bone mineral density and deterioration of bone quality, and it affects millions of people worldwide. Currently, it is treated mainly using antiresorptive and osteoanabolic agents. However, these drugs have severe adverse effects. Cell replacement therapy using mesenchymal stem cells (MSCs) could serve as a treatment strategy for osteoporosis in the future. LIGHT (HVEM-L, TNFSF14, or CD258) is a member of the tumor necrosis factor superfamily. However, the effect of recombinant LIGHT (rhLIGHT) on osteogenesis in human bone marrow-derived MSCs (hBM-MSCs) is unknown. Therefore, we monitored the effects of LIGHT on osteogenesis of hBM-MSCs. Lymphotoxin-ß receptor (LTßR), which is a LIGHT receptor, was constitutively expressed on the surface of hBM-MSCs. After rhLIGHT treatment, calcium and phosphate deposition in hBM-MSCs, stained by Alizarin red and von Kossa, respectively, significantly increased. We performed quantitative real-time polymerase chain reaction to examine the expressions of osteoprogenitor markers (RUNX2/CBFA1 and collagen I alpha 1) and osteoblast markers (alkaline phosphatase, osterix/Sp7, and osteocalcin) and immunoblotting to assess the underlying biological mechanisms following rhLIGHT treatment. We found that rhLIGHT treatment enhanced von Kossa- and Alizarin red-positive hBM-MSCs and induced the expression of diverse differentiation markers of osteogenesis in a dose-dependent manner. WNT/ß-catenin pathway activation strongly mediated rhLIGHT-induced osteogenesis of hBM-MSCs, accelerating the differentiation of hBM-MSCs into osteocytes. In conclusion, the interaction between LIGHT and LTßR enhances osteogenesis of hBM-MSCs. Therefore, LIGHT might play an important role in stem cell therapy.

Radotinib enhances cytarabine (Ara-C)-induced acute myeloid leukemia cell death.

BACKGROUND: Acute myeloid leukemia (AML) is a heterogeneous disease that frequently relapses after standard chemotherapy. Therefore, there is a need for the development of novel chemotherapeutic agents that could treat AML effectively. Radotinib, an oral BCR-ABL tyrosine kinase inhibitor, was developed as a drug for the treatment of chronic myeloid leukemia. Previously, we reported that radotinib exerts increased cytotoxic effects towards AML cells. However, little is known about the effects of combining radotinib with Ara-C, a conventional chemotherapeutic agent for AML, with respect to cell death in AML cells. Therefore, we investigated combination effects of radotinib and Ara-C on AML in this study. METHODS: Synergistic anti-cancer effects of radotinib and Ara-C in AML cells including HL60, HEL92.1.7, THP-1 and bone marrow cells from AML patients have been examined. Diverse cell biological assays such as cell viability assay, Annexin V-positive cells, caspase-3 activity, cell cycle distribution, and related signaling pathway have been performed. RESULTS: The combination of radotinib and Ara-C was found to induce AML cell apoptosis, which involved the mitochondrial pathway. In brief, combined radotinib and Ara-C significantly induced Annexin V-positive cells, cytosolic cytochrome C, and the pro-apoptotic protein Bax in AML cells including HL60, HEL92.1.7, and THP-1. In addition, mitochondrial membrane potential and Bcl-xl protein were markedly decreased by radotinib and Ara-C. Moreover, this combination induced caspase-3 activity. Cleaved caspase-3, 7, and 9 levels were also increased by combined radotinib and Ara-C. Additionally, radotinib and Ara-C co-treatment induced G0/G1 arrest via the induction of CDKIs such as p21 and p27 and the inhibition of CDK2 and cyclin E. Thus, radotinib/Ara-C induces mitochondrial-dependent apoptosis and G0/G1 arrest via the regulation of the CDKI-CDK-cyclin cascade in AML cells. In addition, our results showed that combined treatment with radotinib and Ara-C inhibits AML cell growth, including tumor volumes and weights in vivo. Also, the combination of radotinib and Ara-C can sensitize cells to chemotherapeutic agents such as daunorubicin or idarubicin in AML cells. CONCLUSIONS: Therefore, our results can be concluded that radotinib in combination with Ara-C possesses a strong anti-AML activity.

CD45dimCD34+CD38-CD133+ cells have the potential as leukemic stem cells in acute myeloid leukemia.

BACKGROUND: Leukemia stem cells (LSCs) in play an important role in the initiation, relapse, and progression of acute myeloid leukemia (AML), and in the development of chemotherapeutic drug resistance in AML. Studies regarding the detection of LSCs and the development of novel therapies for targeting them are extensive. The identification of LSCs and targeting therapies for them has been continuously under investigation. METHODS: We examined the levels of CD45dimCD34+CD38-CD133+ cells in bone marrow samples from patients with hematological malignancies and healthy controls, using four-color flow cytometry. RESULTS: Interestingly, the CD45dimCD34+CD38-CD133+ cells were highly expressed in the bone marrow of patients with AML compared to that in healthy controls (HC). Moreover, the proportions of CD45dimCD34+CD38-CD133+ cells were also examined in diverse hematological malignancies, including AML, CML, DLBCL, MM, MDS, HL, ALL, and CLL. LSCs were prominently detected in the BMCs isolated from patients with AML and CML, but rarely in BMCs isolated from patients with DLBCL, MM, MDS, ALL, CLL, and HL. Additionally, the high CD45dimCD34+CD38-CD133+ cell counts in AML patients served as a significantly poor risk factor for overall and event free survival. CONCLUSIONS: Therefore, our results suggest that CD45dimCD34+CD38-CD133+ cells in AML might potentially serve as LSCs. In addition, this cell population might represent a novel therapeutic target in AML.

Radotinib inhibits mitosis entry in acute myeloid leukemia cells via suppression of Aurora kinase A expression.

Aurora kinases play critical roles in regulating several processes pivotal for mitosis. Radotinib, which is approved in South Korea as a second-line treatment for chronic myeloid leukemia, inhibits the tyrosine kinase BCR-ABL and platelet-derived growth factor receptor. However, the effects of radotinib on Aurora kinase expression in acute myeloid leukemia are not well studied. Interestingly, the cytotoxicity of acute myeloid leukemia cells was increased by radotinib treatment. Radotinib significantly decreased the expression of cyclin-dependent kinase 1 and cyclin B1, the key regulators of G2/M phase, and inhibited the expression of Aurora kinase A and Aurora kinase B in acute myeloid leukemia cells. In addition, radotinib decreased the expression and binding between p-Aurora kinase A and TPX2, which are required for spindle assembly. Furthermore, it reduced Aurora kinase A and polo-like kinase 1 phosphorylation and suppressed the expression of α-, ß-, and γ-tubulin in acute myeloid leukemia cells. Furthermore, radotinib significantly suppressed the key regulators of G2/M phase including cyclin B1 and Aurora kinase A in a xenograft animal model. Therefore, our results suggest that radotinib can abrogate acute myeloid leukemia cell growth both in vitro and in vivo and may serve as a candidate agent or a chemosensitizer for treating acute myeloid leukemia.

Rhein augments ATRA-induced differentiation of acute promyelocytic leukemia cells.

BACKGROUND: Rhein (4, 5-dihydroxyanthraquinone-2-carboxylic acid), a natural anthraquinone derivative, is a traditional Chinese herb that has been used as a medication in many Asian countries. It has been used as a laxative and stomach drug for a long time in both China and Korea. It is well-known to have many pharmacological activities, such as anti-cancer, anti-bacterial, anti-fungal, anti-oxidant, anti-atherogenic, anti-angiogenic, anti-fibrosis, anti-inflammatory, hepatoprotective, and nephroprotective properties. However, little is known about how rhein may affect the differentiation activities in acute promyelocytic leukemia (APL) cells. PURPOSE: The present study was designed to examine the anti-leukemic effects of rhein against APL cells and to explore the underlying mechanism. METHODS: Cell viability was investigated by MTS assay. To examine the differentiation activities in APL cells, the cell surface molecules (CD11b, CD14, CCR1 and CCR2), phagocytosis, reactive oxygen species (ROS) were determined by flow cytometry. Also, induction of caspase-3 activity and reduction of mitochondrial membrane potential (MMP) were determined by flow cytometry. RNA and protein expressions were determined by qRT-PCR and western blotting, respectively. RESULTS: In this study we assessed the role of rhein in treating APL. Interestingly, rhein potentiated all-trans retinoic acid (ATRA)-induced macrophage differentiation in NB4 cells by inducing changes in morphology, expression of the differentiation markers CD11b and CD14, ROS production, phagocytic activity, and expression of CCR1 and CCR2. Signaling through CD11b was found to be dependent on ERK activation. Additionally, rhein induced APL cell death by activating apoptosis and suppressing the mTOR pathway. CONCLUSION: Therefore, we suggest that a combination of rhein and ATRA carries strong therapeutic potential through the beneficial differentiation of APL cells. Moreover, rhein causes cell death via the activation of apoptosis and suppression of survival signals in APL cells. In combination with the ability of rhein to promote functional macrophage differentiation in APL, these properties suggest that a combined treatment of rhein and ATRA has great potential as an anti-leukemic therapy for APL.

Targeting c-KIT (CD117) by dasatinib and radotinib promotes acute myeloid leukemia cell death.

Dasatinib and radotinib are oral BCR-ABL tyrosine kinase inhibitors that were developed as drugs for the treatment of chronic myeloid leukemia. We report here that the c-KIT (CD117) targeting with dasatinib and radotinib promotes acute myeloid leukemia (AML) cell death, and c-KIT endocytosis is essential for triggering c-KIT-positive AML cell death by dasatinib and radotinib during the early stages. In addition, dasatinib and radotinib reduce heat shock protein 90ß (HSP90ß) expression and release Apaf-1 in c-KIT-positive AML cells. Finally, this activates a caspase-dependent apoptotic pathway in c-KIT-positive AML cells. Moreover, the inhibition of c-KIT endocytosis by dynamin inhibitor (DY) reversed cell viability and c-KIT expression by dasatinib and radotinib. HSP90ß expression was recovered by DY in c-KIT-positive AML cells as well. Furthermore, the effect of radotinib on c-KIT and HSP90ß showed the same pattern in a xenograft animal model using HEL92.1.7 cells. Therefore, dasatinib and radotinib promote AML cell death by targeting c-KIT. Taken together, these results indicate that dasatinib and radotinib treatment have a potential role in anti-leukemic therapy on c-KIT-positive AML cells.

Radotinib induces high cytotoxicity in c-KIT positive acute myeloid leukemia cells.

Previously, we reported that radotinib, a BCR-ABL1 tyrosine kinase inhibitor, induced cytotoxicity in acute myeloid leukemia (AML) cells. However, the effects of radotinib in the subpopulation of c-KIT-positive AML cells were unclear. We observed that low-concentration radotinib had more potent cytotoxicity in c-KIT-positive cells than c-KIT-negative cells from AML patients. To address this issue, cell lines with high c-KIT expression, HEL92.1.7, and moderate c-KIT expression, H209, were selected. HEL92.1.7 cells were grouped into intermediate and high c-KIT expression populations. The cytotoxicity of radotinib against the HEL92.1.7 cell population with intermediate c-KIT expression was not different from that of the population with high c-KIT expression. When H209 cells were grouped into c-KIT expression-negative and c-KIT expression-positive populations, radotinib induced cytotoxicity in the c-KIT-positive population, but not the c-KIT-negative population. Thus, radotinib induces cytotoxicity in c-KIT-positive cells, regardless of the c-KIT expression intensity. Therefore, radotinib induces significant cytotoxicity in c-KIT-positive AML cells, suggesting that radotinib is a potential target agent for the treatment of c-KIT-positive malignancies including AML.

LIGHT (TNFSF14) Increases the Survival and Proliferation of Human Bone Marrow-Derived Mesenchymal Stem Cells.

LIGHT (HVEM-L, TNFSF14, or CD258), an entity homologous to lymphotoxins, with inducible nature and the ability to compete with herpes simplex virus glycoprotein D for herpes virus entry mediator (HVEM)/tumor necrosis factor (TNF)-related 2, is a member of the TNF superfamily. It is expressed as a homotrimer on activated T cells and dendritic cells (DCs), and has three receptors: HVEM, LT-ß receptor (LTßR), and decoy receptor 3 (DcR3). So far, three receptors with distinct cellular expression patterns are known to interact with LIGHT. Follicular DCs and stromal cells bind LIGHT through LTßR. We monitored the effects of LIGHT on human bone marrow-derived mesenchymal stem cells (BM-MSCs). At first, we checked the negative and positive differentiation markers of BM-MSCs. And we confirmed the quality of MSCs by staining cells undergoing adipogenesis (Oil Red O staining), chondrogenesis (Alcian blue staining), and osteogenesis (Alizarin red staining). After rhLIGHT treatment, we monitored the count, viability, and proliferation of cells and cell cycle distribution. PDGF and TGFß production by rhLIGHT was examined by ELISA, and the underlying biological mechanisms were studied by immunoblotting by rhLIGHT treatment. LTßR was constitutively expressed on the surface of human BM-MSCs. Cell number and viability increased after rhLIGHT treatment. BM-MSC proliferation was induced by an increase in the S/G2/M phase. The expression of not only diverse cyclins such as cyclin B1, D1, D3, and E, but also CDK1 and CDK2, increased, while that of p27 decreased, after rhLIGHT treatment. RhLIGHT-induced PDGF and TGFß production mediated by STAT3 and Smad3 activation accelerated BM-MSC proliferation. Thus, LIGHT and LTßR interaction increases the survival and proliferation of human BM-MSCs, and therefore, LIGHT might play an important role in stem cell therapy.

Radotinib inhibits acute myeloid leukemia cell proliferation via induction of mitochondrial-dependent apoptosis and CDK inhibitors.

Radotinib is a BCR-ABL1 tyrosine kinase inhibitor approved for the second-line treatment of chronic myeloid leukemia. However, effects of radotinib on acute myeloid leukemia (AML) are unclear. In the present study, we observed that radotinib exerted cytotoxic effects on AML cells. Of the various AML cell lines examined (NB4, HL60, HEL 92.1.7, and THP-1), Kasumi-1 was the most sensitive to radotinib. Results of microarray analysis showed that 417 and 595 genes associated with apoptosis and cell cycle regulation, respectively, were differently expressed (i.e., showed >2-fold difference in expression). Radotinib-induced apoptosis involved the mitochondrial pathway. Moreover, radotinib increased the apoptosis of and induced caspase-3 activity in both Kasumi-1 cells and bone marrow cells (BMCs) obtained from patients with AML. Radotinib also increased cleaved caspase-3, caspase-7, and caspase-9 levels and decreased the number of proliferating Kasumi-1 cells and BMCs from patients with AML. In addition, radotinib induced G0/G1 phase arrest by inducing CDKIs p21 and p27 and by inhibiting CDK2, CDK4, and CDK6. These results indicate that radotinib induces caspase-dependent apoptosis and G0/G1 phase arrest in AML cells by regulating CDKI-CDK-cyclin cascade. Moreover, these results indicate that radotinib inhibits AML cell proliferation by inducing mitochondria-dependent apoptosis and CDKIs p21 and p27. To our knowledge, this is the first study to show that radotinib can be potentially used for the anti-leukemic therapy of patients with AML.

Radotinib Induces Apoptosis of CD11b+ Cells Differentiated from Acute Myeloid Leukemia Cells.

Radotinib, developed as a BCR/ABL tyrosine kinase inhibitor (TKI), is approved for the second-line treatment of chronic myeloid leukemia (CML) in South Korea. However, therapeutic effects of radotinib in acute myeloid leukemia (AML) are unknown. In the present study, we demonstrate that radotinib significantly decreases the viability of AML cells in a dose-dependent manner. Kasumi-1 cells were more sensitive to radotinib than NB4, HL60, or THP-1 cell lines. Furthermore, radotinib induced CD11b expression in NB4, THP-1, and Kasumi-1 cells either in presence or absence of all trans-retinoic acid (ATRA). We found that radotinib promoted differentiation and induced CD11b expression in AML cells by downregulating LYN. However, CD11b expression induced by ATRA in HL60 cells was decreased by radotinib through upregulation of LYN. Furthermore, radotinib mainly induced apoptosis of CD11b+ cells in the total population of AML cells. Radotinib also increased apoptosis of CD11b+ HL60 cells when they were differentiated by ATRA/dasatinib treatment. We show that radotinib induced apoptosis via caspase-3 activation and the loss of mitochondrial membrane potential (ΔΨm) in CD11b+ cells differentiated from AML cells. Our results suggest that radotinib may be used as a candidate drug in AML or a chemosensitizer for treatment of AML by other therapeutics.

Rosmarinic acid potentiates ATRA-induced macrophage differentiation in acute promyelocytic leukemia NB4 cells.

Rosmarinic acid (RA, an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid) has a number of biological activities, but little is known about anti-leukemic activities of RA combined with all-trans retinoic acid (ATRA) against acute promyelocytic leukemia (APL) cells. We examined the differentiation marker, CD11b, in bone marrow cells (BMC) of an APL patient, in NB4 cells (APL cell line), and in normal BMC and peripheral blood mononuclear cells (PBMC) of healthy subjects by flow cytometric analysis. ATRA/RA induced expression of CD11b in the BMC of the APL patient and in NB4 cells, but not in normal BMC or PBMC. Therefore, we realized that RA potentiated ATRA-induced macrophage differentiation in APL cells. Further characterization of the induced macrophages showed that they exhibited morphological changes and were able to phagocytose and generate reactive oxygen species. Th also had typical expression of C-C chemokine receptor type 1 (CCR1), CCR2, and intercellular adhesion molecule-1 (ICAM-1). Moreover, the expression of CD11b(+) and CD14(+) cells depended on ERK-NF-κB axis activation. Together, these results indicate that RA potentiates ATRA-induced macrophage differentiation in APL cells. Thus, RA may play an important role as an appurtenant differentiation agent for functional macrophage differentiation in APL. Additionally, the differentiated macrophages might have a normal life span and, they could die. These data indicate that co-treatment with RA and ATRA has potential as an anti-leukemic therapy in APL.

Dasatinib accelerates valproic acid-induced acute myeloid leukemia cell death by regulation of differentiation capacity.

Dasatinib is a compound developed for chronic myeloid leukemia as a multi-targeted kinase inhibitor against wild-type BCR-ABL and SRC family kinases. Valproic acid (VPA) is an anti-epileptic drug that also acts as a class I histone deacetylase inhibitor. The aim of this research was to determine the anti-leukemic effects of dasatinib and VPA in combination and to identify their mechanism of action in acute myeloid leukemia (AML) cells. Dasatinib was found to exert potent synergistic inhibitory effects on VPA-treated AML cells in association with G1 phase cell cycle arrest and apoptosis induction involving the cleavage of poly (ADP-ribose) polymerase and caspase-3, -7 and -9. Dasatinib/VPA-induced cell death thus occurred via caspase-dependent apoptosis. Moreover, MEK/ERK and p38 MAPK inhibitors efficiently inhibited dasatinib/VPA-induced apoptosis. The combined effect of dasatinib and VPA on the differentiation capacity of AML cells was more powerful than the effect of each drug alone, being sufficiently strong to promote AML cell death through G1 cell cycle arrest and caspase-dependent apoptosis. MEK/ERK and p38 MAPK were found to control dasatinib/VPA-induced apoptosis as upstream regulators, and co-treatment with dasatinib and VPA to contribute to AML cell death through the regulation of differentiation capacity. Taken together, these results indicate that combined dasatinib and VPA treatment has a potential role in anti-leukemic therapy.

Activation of Nod1 and Nod2 induces innate immune responses of prostate epithelial cells.

BACKGROUND: Nod1 and Nod2 are cytosolic receptors which are responsible for sensing bacterial peptidoglycan derivatives. In this study, we determined whether Nod1 and Nod2 are involved in the innate immune responses of prostate epithelial cells. METHODS: The expression of Nod1 and Nod2 was examined by RT-PCR and immunohistochemistry. ELISA was performed to determine the production of cytokines/chemokines. Activation of NF-κB and MAPK was examined using western blot analysis. RESULTS: The Nod1 gene was distinctly expressed in all tested cells including DU145, PC3, and TRAMP-C2 cells, whereas Nod2 expression was weak. Both Nod1 and Nod2 proteins were expressed in normal mouse prostate epithelia with difference of expression levels. Tri-DAP (Nod1 agonist), but not MDP (Nod2), increased the production of IL-8 (or KC) and IL-6 in prostate epithelial cells. Tri-DAP and MDP could upregulate the gene expression of COX-2 and activate NF-κB and MAPK. In addition, Tri-DAP and MDP synergized with TLR agonists to induce the production of IL-8/KC or IL-6 in PC3 and TRAMP-C2 cells. We finally showed that Nod1 and Nod2 were also expressed in a wide range of prostate lesions including prostate intraepithelial neoplasm (PIN), phyllodes-like tumor, and adenocarcinoma in TRAMP (transgenic adenocarcinoma of the mouse prostate) mice, even though the expression level of Nod1 and Nod2 was different. CONCLUSION: These results indicate that Nod1 and Nod2 may play important roles in the innate immune response of prostate epithelial cells and the development and progression of prostate cancer.

The presence of high level soluble herpes virus entry mediator in sera of gastric cancer patients.

The development of gastric cancer (GC) is closely related to chronic inflammation caused by Helicobacter pylori infection, and herpes virus entry mediator (HVEM) is a receptor expressed on the surface of leukocytes that mediates potent inflammatory responses in animal models. However, the role of HVEM in human GC has not been studied. Previously, we showed that the interaction of HVEM on human leukocytes with its ligand LIGHT induces intracellular calcium mobilization, which results in inflammatory responses including induction of proinflammatory cytokine production and anti-bacterial activities. In this study, we report that leukocytes from GC patients express lower levels of membrane HVEM (mHVEM) and have lower LIGHT-induced bactericidal activities than those from healthy controls (HC). In contrast, levels of soluble HVEM (sHVEM) in the sera of GC patients were significantly higher than in those of HC. We found that monocyte membrane-bound HVEM is released into the medium when cells are activated by proinflammatory cytokines such as TNF-α and IL-8, which are elevated in the sera of GC patients. mHVEM level dropped in parallel with the release of sHVEM, and release was completely blocked by the metalloprotease inhibitor, GM6001. We also found that the low level of mHVEM on GC patient leukocytes was correlated with low LIGHT-induced bactericidal activities against H. pylori and S. aureus and production of reactive oxygen species. Our results indicate that mHVEM on leukocytes and sHVEM in sera may contribute to the development and/or progression of GC.

Emodin and rhein inhibit LIGHT-induced monocytes migration by blocking of ROS production.

LIGHT is known to act as a novel mediator for atherogenesis. Furthermore, it has been reported that emodin, an active component extracted from rhubarb, can stop the growth of cancer cells. However, it is not known if emodin exerts anti-atherogenic effects in the human monocyte, THP-1, following treatment with LIGHT. In this study, we evaluated the inhibitory effect of emodin and rhein on LIGHT-induced migration in THP-1. Emodin and rhein decreased the level of LIGHT-induced generation of ROS, as well as the expression of CCR1, CCR2 and ICAM-1 and the production of IL-8, MCP-1, TNF-alpha, and IL-6. Emodin and rhein also decreased the phosphorylation of the p38 MAPK and IkB-alpha. Furthermore, the NADPH oxidase assembly inhibitor, AEBSF, and the blocker of NADPH oxidase, p47(phox) small interference RNA (siRNA), also efficiently blocked LIGHT-induced migration, CCR1, CCR2, ICAM-1, and HVEM expression, and p38 MAPK and NF-kB activation. These findings indicate that the inhibitory effects of emodin and rhein on LIGHT-induced migration occur via decreasing ROS production and NADPH oxidase p47(phox) activation. Taken together, these results indicate that emodin and rhein have the potential for use as an anti-atherosclerosis agent.