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Extranodal NK/T cell lymphoma (ENKL) is a rare subtype of lymphoma that shows a poor clinical outcome. The most common sites are the nasal cavity, nasopharynx, paranasal sinuses, tonsils and larynx. Because of P-glycoprotein expression on ENKL cells, ENKL is resistant to anthracycline-based chemotherapy. L-asparaginase-based chemotherapy with or without radiotherapy shows promising outcomes for advanced ENKL, but has limited efficacy in relapsed/refractory ENKL. immune-checkpoint inhibitors, histone deacetylase inhibitors, and monoclonal antibodies are being investigated. In this review, we summarize the new treatments for ENKL.

Marsdenia tenacissimae extraction (MTE), a traditional herbal medicine, has exhibited anti-tumor effects on a variety of cancers. However, its effectiveness and the mechanism of action in Hepatocellular carcinoma (HCC) has not been fully understood. In the present study, we demonstrate that C21 steroid-enriched fraction from MTE, which contains five main C21 steroids (FR5) exhibits obvious pharmacological activities on HCC cells in vitro and in vivo. FR5 induces apoptosis and inhibits proliferation and migration of HepG2 and Bel7402 cells in a dose and time dependent manner. Furthermore, in HCC cells, we found that FR5 inhibits Hippo pathway, leading to inactivation of YAP and increase of PTEN. Enhanced PTEN results in the inhibition of PI3K/AKT signaling pathway, inhibiting cell proliferation by FR5 and FR5-induced apoptosis. Moreover, it was proved that FR5 treatment could inhibit tumor growth in a HCC xenograft mouse model, and immunohistochemistry results showed FR5 treatment resulted in down-regulation of Bcl-2 and YAP, and up-regulation of PTEN and PI3K. Taken together, we found that FR5 effectively inhibits proliferation and induces apoptosis of HCC cells through coordinated inhibition of YAP in the Hippo pathway and AKT in the PI3K-PTEN-mTOR pathway, and suggest FR5 as a potential therapy for HCC.

To examine whether a combinative treatment with curcumin enhances the effects of the epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) gefitinib on cell proliferation, clonogenic capacity and apoptosis in the drug-resistant lung cancer cell line NCI-H1975, and further investigate the molecular mechanisms involved.NCI-H1975 cells were treated with curcumin and gefitinib alone or in combination, and cell proliferation, clonogenic capacity and apoptosis were examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, clone forming experiments, and flow cytometry, respectively, while p38, extracellular regulated protein kinase (ERK)1/2, and protein kinase B (AKT) phosphorylation were examined using Western blotting.Compared with the effects of either agent alone, the combination of curcumin and gefitinib had a stronger suppressive effect on proliferation and the clonogenic capacity (P0.05), and showed an increased ability to promote apoptosis (P0.05) and reduce p38, ERK1/2, and AKT phosphorylation (P0.05).Co-treatment of curcumin and gefitinib significantly improves the ability of gefitinib to inhibit cell proliferation, suppress the clonogenic capacity and enhance apoptosis in NCI-H1975 cells, and these effects are possibly mediated via a decrease in phosphorylation of proteins in downstream pathways of the epidermal growth factor receptor.

Hindlimb unloading, as a simulation of microgravity, decreases the osteogenic potential of mesenchymal stem cells (MSCs) from hindlimb femur of rat. We simulated the microgravity by 28-day of hindlimb unloading for male Sprague-Dawley rat, and performed intramuscular injection of BMP-2 and FGF2 at a given interval during hindlimb unloading. Then, the bone marrow (BM) was collected from hindlimb femur of rat. MSCs were isolated from BM, cultured for four passages, and then induced for osteogenesis. The results revealed that the hindlimb unloading decreased the osteogenic potential of MSCs and also the expression of osteoblast gene marker mRNAs in cells induced by osteogenic conditions. Hindlimb unloading for 28 days resulted in the decrease of vinculin-containing focal adhesion in MSCs. During hindlimb unloading, the interval intramuscular injection of BMP-2 or FGF2 alone could increase the osteogenic potential of MSCs and the expression of osteoblast gene marker mRNA. However, the effect of BMP-2 or FGF2 injection alone was significantly lower than that of combination injection of both factors. The further examination showed that the intramuscular injection of BMP-2 promoted the expression of Runx2 mRNA and that the intramuscular injection of FGF2 increased the phosphorylation of ERK and Runx2. Nevertheless, the intramuscular injection of any factor could not increase the formation of vinculin-containing focal adhesions in MSCs. This suggests that BMP-2 should increase the expression of Runx2, and that the activation of Runx2 should be promoted by the FGF2 signaling pathway which activated ERK/Runx2. The activation of this signaling pathway should not lie on the formation of vinculin-containing focal adhesions.

Epac, exchange protein activated by cyclic adenosine monophosphate (cAMP), could regulate the trans-differentiation between adipogenesis and osteogenesis of human mesenchymal stem cells (hMSCs). Epac activated by 8-pCPT-2′- O -Me-cAMP, a cAMP analog preferentially activating Epac, resulted in the increase of adipogenic gene expression and the decrease of osteogenic gene expression. The pro-adipogenic and anti-osteogenic effect of 8-pCPT-2′- O -Me-cAMP was attributed to that 8-pCPT-2′- O -Me-cAMP led to the activation of protein kinase B (PKB) and cAMP response element-binding protein (CREB) as well as the inhibition of Ras homolog gene family member A (RhoA), focal adhesion kinase (FAK), extracellular-signal-regulated kinase (ERK) and runt-related transcription factor 2 (Runx2) activities. Inhibition of Epac by a dominant-negative form of Epac1 resulted in the decrease of phosphatidylinositol 3-kinase (PI3K), PKB and CREB activities as well as down-regulation of peroxisome proliferator activated receptor-γ (PPARγ) expression. Inhibition of PI3K by a specific inhibitor or inhibition of Arf and Rho GAP adapter protein 3 (ARAP3, a phosphatidylinositol (PtdIns)(3,4,5)P 3 binding protein) by ARAP3 siRNA led to the recovery of RhoA and FAK activities. RhoA-V14, a constitutively active form of RhoA, could activate the MEK/ERK/Runx2 signaling. Therefore, we conclude that PI3K activated by Epac leads to the activation of PKB/CREB signaling and the up-regulation of PPARγ expression, which in turn activate the transcription of adipogenic genes; whereas osteogenesis is driven by Rho/FAK/MEK/ERK/Runx2 signaling, which can be inhibited by Epac via PI3K. These results should be helpful to provide new targets for treatment of osteoporosis and related bone-wasting diseases.

Fluid shear stress (FSS) is an important biomechanical factor regulating the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and is therefore widely used in bone tissue engineering. However, the mechanotransduction of FSS in hMSCs remains largely unknown. As β1 integrins are considered to be important mechanoreceptors in other cells, we suspect that β1 integrins should also be important for hMSCs to sense the stimulation of FSS. We used a perfusion culture system to produce FSS loading on hMSCs seeded in PLGA three-dimensional (3D) scaffolds and investigated the roles of β1 integrins, FAK and ERK1/2 in FSS-induced osteogenic differentiation of hMSCs. Our results showed that FSS not only markedly increased ALP activity and the expression of ALP, OCN, Runx2 and COLIα genes but also significantly enhanced the phosphorylation of ERK1/2, Runx2 and FAK. FSS-induced activation of ERK1/2 and FAK was inhibited by blockade of the connection between β1 integrins and ECM with RGDS peptide and integrins β1 monoclonal antibody. Our study also found that FSS could upregulate the expression level of β1 integrins and that this upregulation could be abolished by PD98059. Further investigation indicated that FSS-activated ERK1/2 led to the phosphorylation of IκBα and NFκB p65. The activation of NFκB p65 resulted in the upregulation of β1 integrin expression. Therefore, it could be inferred that β1 integrins should sense the stimulation of FSS and thus activate ERK1/2 through activating of FAK, and FSS-activated ERK1/2 feedback to upregulate the expression of β1 integrins through activating NFκB.

A reasonable mechanical microenvironment similar to the bone microenvironment in vivo is critical to the formation of engineering bone tissues. As fluid shear stress (FSS) produced by perfusion culture system can lead to the osteogenic differentiation of human mesenchymal stem cells (hMSCs), it is widely used in studies of bone tissue engineering. However, effects of FSS on the differentiation of hMSCs largely depend on the FSS application manner. It is interesting how different FSS application manners influence the differentiation of hMSCs. In this study, we examined the effects of intermittent FSS and continuous FSS on the osteogenic differentiation of hMSCs. The phosphorylation level of ERK1/2 and FAK is measured to investigate the effects of different FSS application manners on the activation of signaling molecules. The results showed that intermittent FSS could promote the osteogenic differentiation of hMSCs. The expression level of osteogenic genes and the alkaline phosphatase (ALP) activity in cells under intermittent FSS application were significantly higher than those in cells under continuous FSS application. Moreover, intermittent FSS up-regulated the activity of ERK1/2 and FAK. Our study demonstrated that intermittent FSS is more effective to induce the osteogenic differentiation of hMSCs than continuous FSS.

Objective: To explore the influence of the retinoic acid indicible gene–I (RIG-I) on hepatitis C virus (HCV) replication and the molecular mechanism of action of RIG-I. Methods: We constructed an RIG-I expression vector and co-transfected it into Huh-7 cells along with HCV-replicon RNA. We assayed HCV replication and NS5A protein synthesis via real-time polymerase chain reaction (RT-PCR) and western blotting. Also, we performed an enzyme-linked immunosorbent assay (ELISA) to measure the level of interferon (IFN)–α/-β secretion. Additionally, we examined, via western blotting, the phosphorylation state of p38, Erk1/2, and nuclear factor (NF)–κB p65. Results: Overexpression of RIG-1 in Huh-7 cells co-transfected with an HCV-replicon RNA significantly inhibited HCV replication and NS5A protein synthesis. Co-transfected cells had increased production of IFN- α/-β production and had higher levels of phosphorylated p38, Erk1/2, and NF-κB p65. Conclusions: RIG-I significantly inhibits HCV replication and NS5A protein synthesis by inducing type I IFN production. The underlying molecular mechanism for this effect appears to be mediated by increased phosphorylation of NF-κB p65, p38–mitogen-activated protein kinases (MAPK), and Erk1/2. * HCV : hepatitis C virus PRRs : pattern recognition receptors TLR : toll-like receptor RIG-I : retinoic acid inducible gene-I CARDs : caspase activation and recruitment domains INF : interferon IPS-1 : IFN-β promoter-stimulator 1 NF : nuclear factor IRF-3 : IFN regulatory factor 3 DMEM : Dulbecco minimal essential medium cDNA : complementary DNA RT-PCR : real-time polymerase chain reaction PBS : phosphate-buffered solution IgG : immunoglobulin G Na2EDTA : disodium salt of ethylenediaminetetraacetic acid EGTA : ethylene glycol tetraacetic acid SDS : sodium dodecyl sulfate PVDF : polyvinylidene difluoride HRP : horseradish peroxidase ANOVA : analysis of variance PAMPs : pattern-associated molecular patterns MAVS : mitochondrial antiviral-signaling protein TRAF : TNF receptor-associated factors TANK : TRAF-associated NF-κB activator IKK-I : Iκβ kinase ATPase : adenosine triphosphatase MAPK : mitogen-activated protein kinase pathway mRNA : messenger RNA JMK : c-Jun N-terminal kinase ERK : extracellular regulated kinase BGH pA : bovine growth hormone polyadenylation ori : origin pUC : plasmid University of California

Human mesenchymal stem cells (hMSCs) are one of the important factors that regulate bone anabolism. Osteoporosis resulting from microgravity during spaceflight may possibly be due to a decrease in osteogenesis mediated by hMSCs. This speculation should be verified through culture and osteogenic induction of hMSCs in a microgravity environment during spaceflight. Control of CO2 is a key component in current experimental protocols for growth, survival, and proliferation of in vitro cultured cells. However, carrying CO2 tanks on a spaceflight and devoting space/mass allowances for classical CO2 control protocols make experimentation on culture and osteogenesis difficult during most missions. Therefore, an experimental culture and osteogenic medium was developed through modifying the components of buffer salts in conventional culture medium. This experimental medium was used to culture and induce hMSCs under CO2-independent conditions. The results showed that culture and induction of hMSCs with conventional culture medium and conventional osteogenic medium under CO2-independent conditions resulted in an increase of pH in medium. The proliferation of hMSCs was also inhibited. hMSCs cultured with experimental culture medium under CO2-independent conditions showed a proliferation potential that was the same as those cultured with conventional culture medium under CO2-dependent conditions. The experimental osteogenic medium could promote hMSCs to differentiate into osteoblast-like cells under CO2-independent conditions. Cells induced by this induction system showed high alkaline phosphatase activity. The expression levels of osteogenic genes in cells induced with experimental osteogenic medium under CO2-independent conditions were not significantly different from those cells induced with conventional osteogenic medium under CO2-dependent conditions. These results suggest that the experimental culture and induction system could be used to culture hMSCs and induce the osteogenesis of hMSCs in the atmospheric conditions common to spaceflights without additional CO2. Key Words: hMSCs—CO2-independent culture—Osteogenic differentiation—Proliferation. Astrobiology 13, 370–379.

It is a classical signaling pathway that the activation of extracellular signal-regulated kinase1/2 (ERK1/2) results in the phosphorylation of runt-related transcription factor 2 (Runx2) and thereby initiates the transcription of osteogenic genes. Recently, it is found that the activation of ERK1/2 resulted from fluid shear stress (FSS) also increased the expression of Runx2 and β1 integrins, and finally enhanced osteogenic differentiation. However, it has been remained largely unknown how ERK1/2 regulates the expression of Runx2 and β1 integrins. We use the perfusion culture system to produce FSS exerting on human bone marrow-derived mesenchymal stem cells (hMSCs) and thus activate ERK1/2. Our study demonstrated that FSS-activated ERK1/2 mediated the expression of osteogenic genes via two novel signaling pathways except for the classical signaling pathway: feedback up-regulation of β1 integrins expression via activating nuclear factor kappa B (NF-κB), and activation of bone morphogenesis proteins (BMPs)/mothers against decapentaplegic (Smad) pathway via activating NF-κB and thereby regulating Runx2 expression. These signaling pathways combined with the classical signaling pathway, with ERK1/2 as a hub node molecule, form a molecular signaling cross-talking network to induce the osteogenic differentiation of hMSCs. The understanding on the mechanism of FSS inducing the osteogenic differentiation of hMSCs will not only be helpful to develop the bone tissue engineering but also provide new targets for drug discovery for treatment of osteoporosis and other related bone-wasting diseases.

Fluid shear stress (FSS) is an important biomechanical factor regulating the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and is therefore widely used in bone tissue engineering. However, the mechanotransduction of FSS in hMSCs remains largely unknown. As β1 integrins are considered to be important mechanoreceptors in other cells, we suspect that β1 integrins should also be important for hMSCs to sense the stimulation of FSS. We used a perfusion culture system to produce FSS loading on hMSCs seeded in PLGA three-dimensional (3D) scaffolds and investigated the roles of β1 integrins, FAK and ERK1/2 in FSS-induced osteogenic differentiation of hMSCs. Our results showed that FSS not only markedly increased ALP activity and the expression of ALP, OCN, Runx2 and COLIα genes but also significantly enhanced the phosphorylation of ERK1/2, Runx2 and FAK. FSS-induced activation of ERK1/2 and FAK was inhibited by blockade of the connection between β1 integrins and ECM with RGDS peptide and integrins β1 monoclonal antibody. Our study also found that FSS could upregulate the expression level of β1 integrins and that this upregulation could be abolished by PD98059. Further investigation indicated that FSS-activated ERK1/2 led to the phosphorylation of IκBα and NFκB p65. The activation of NFκB p65 resulted in the upregulation of β1 integrin expression. Therefore, it could be inferred that β1 integrins should sense the stimulation of FSS and thus activate ERK1/2 through activating of FAK, and FSS-activated ERK1/2 feedback to upregulate the expression of β1 integrins through activating NFκB.