Mechanism research of non-coding RNA in immune checkpoint inhibitors therapy.

Immune checkpoint inhibitor (ICI) therapies for tumors of different systems have attained significant achievements and have changed the current situation of tumor treatment due to their therapeutic characteristics of high specificity and low side effects. The immune checkpoint Programmed death 1/Programmed cell death-Ligand 1 (PD-1/PD-L1) axis exerts a vital role in the immune escape of tumor cells. As a result, it has become a key target for tumor immunotherapy. Therefore, to perfect research into potential regulatory factors for the PD-1/PD-L1 axis, in order to understand and illustrate tumor ICI therapy mechanisms, is a significant goal. Moreover, ncRNA has been verified to regulate the PD-1/PD-L1 axis in the tumor immune microenvironment to regulate tumor genesis and development. ncRNAs can improve or decrease the efficacy of ICI therapy by modulating PD-L1 expression. This review aimed to investigate the mechanisms of action of ncRNA in regulating the PD-1/PD-L1 axis in ICI therapy, to provide more efficient immunotherapy for tumors of different systems.

Impacts of inflammatory cytokines on depression: a cohort study.

BACKGROUND: Inflammatory factors are associated with depression. We seek to investigate the correlation between inflammatory cytokines and prognosis of depression or suicidal ideation and behavior at 3 months in depression patients. METHODS: Eighty-two depressed outpatients were recruited and treated as usual. Plasma cytokines were measured at baseline. Patients were followed up with Patient Health Questionnaire-9 and suicidal ideation and behavior according to the item 3 of Hamilton depression scale for 3 months. RESULTS: Compared to the depression patients with low level of interleukin-1ß, the high one had severe depressive symptoms at month 2 and 3 (B 0.92, P < 0.01; B 0.86, P = 0.02; respectively). The incidence of suicidal ideation or behavior was 18.3% at 3 months. Depression patients with high levels of tumor necrosis factor-α showed high risk of suicidal ideation and behavior than the low one (OR 2.16, 95% CI 1.00-4.65, P = 0.04). CONCLUSIONS: High levels of interleukin-1ß and tumor necrosis factor-α were predictive of middle-term severe depressive symptoms and suicidal ideation and behavior respectively.

Carboxyl group-modified myoglobin shows membrane-permeabilizing activity.

In this study, we investigated whether modification of the carboxyl group with semicarbazide-enabled myoglobin (Mb) exhibits membrane-perturbing activity in physiological solutions. Mass spectrometry analysis showed that semicarbazide molecules were coupled to 19 of the 22 carboxyl groups in semicarbazide-modified Mb (SEM-Mb). Measurements of the absorption and circular dichroism spectra indicated that SEM-Mb lost its heme group and reduced the content of the α-helix structure in Mb. The microenvironment surrounding Trp residues in Mb changes after blocking negatively charged residues, as shown by fluorescence quenching studies. The results of the trifluoroethanol-induced structural transition indicated that SEM-Mb had higher structural flexibility than that of Mb. SEM-Mb, but not Mb, induced the permeability of bilayer membranes. Both proteins showed similar lipid-binding affinities. The conformation of SEM-Mb and Mb changed upon binding to lipid vesicles or a membrane-mimicking environment composed of SDS micelles, suggesting that membrane interaction modes differ. Unlike lipid-bound Mb, Trp residues in lipid-bound SEM-Mb are located at the protein-lipid interface. Altogether, our data indicate that modifying negatively charged groups relieves the structural constraints in Mb, consequently switching Mb structure to an active conformation that exhibits membrane-permeabilizing activity.

Functional and structural properties of cardiotoxin isomers produced by blocking negatively charged groups.

In this study, we investigated the functional roles of Asp40, Asp57, and C-terminal Asn60 in Naja atra cardiotoxin 3 (CTX3) structure and function by modifying these three carboxyl groups with semicarbazide. The conjugation of the carboxyl groups with semicarbazide produced two conformational isomers whose gross and fine structures were different from those of CTX3. The blocking of the carboxyl groups increased the structural flexibility of CTX3 in response to trifluoroethanol-induced effect. Despite presenting modest to no effect on decreasing the induction of permeability in zwitterionic phospholipid vesicles, the carboxyl group-modified CTX3 showed a marked reduction in its permeabilizing effect on anionic phospholipid vesicles in comparison to that of the native protein. Compared with native CTX3, carboxyl group-modified CTX3 exhibited lower activity in inducing membrane leakage in U937 cells. The CD spectra of lipid-bound toxins and the color transition of polydiacetylene/lipid assay showed that the membrane interaction mode of CTX3 was distinctly changed by the modification in the carboxyl groups. Given that the selective modification of Asp40 does not cause the conformational isomerization of CTX3, our data indicate that the carboxyl groups in Asp57 and Asn60 are essential in maintaining the structural topology of CTX3. Furthermore, modification of carboxyl groups changes the interdependence between the infrastructure and the global conformation of CTX3 in modulating membrane permeabilizing activity.

NOXA-mediated degradation of MCL1 and BCL2L1 causes apoptosis of daunorubicin-treated human acute myeloid leukemia cells.

Daunorubicin (DNR) is used clinically to treat acute myeloid leukemia (AML), while the signaling pathways associated with its cytotoxicity are not fully elucidated. Thus, we investigated the DNR-induced death pathway in the human AML cell lines U937 and HL-60. DNR-induced apoptosis in U937 cells accompanied by downregulation of MCL1 and BCL2L1, upregulation of Phorbol-12-myristate-13-acetate-induced protein 1 (NOXA), and mitochondrial depolarization. DNR induced NOX4-mediated reactive reactive oxygen species (ROS) production, which in turn inactivated Akt and simultaneously activated p38 mitogen-activated protein kinase (MAPK). Activated p38 MAPK and inactivated Akt coordinately increased GSK3ß-mediated cAMP response element-binding protein (CREB) phosphorylation, which promoted NOXA transcription. NOXA upregulation critically increased the proteasomal degradation of MCL1 and BCL2L1. The same pathway was also responsible for the DNR-induced death of HL-60 cells. Restoration of MCL1 or BCL2L1 expression alleviated DNR-induced mitochondrial depolarization and cell death. Furthermore, ABT-199 (a BCL2 inhibitor) synergistically enhanced the cytotoxicity of DNR in AML cell lines. Notably, DNR-induced DNA damage was not related to NOXA-mediated degradation of MCL1 and BCL2L1. Collectively, these results indicate that the upregulation of NOXA expression through the NOX4-ROS-p38 MAPK-GSK3ß-CREB axis results in the degradation of MCL1 and BCL2L1 in DNR-treated U937 and HL-60 cells. This signaling pathway may provide insights into the mechanism underlying DNR-triggered apoptosis in AML cells.

GSK3ß suppression inhibits MCL1 protein synthesis in human acute myeloid leukemia cells.

Previous studies have shown that glycogen synthase kinase 3ß (GSK3ß) suppression is a potential strategy for human acute myeloid leukemia (AML) therapy. However, the cytotoxic mechanism associated with GSK3ß suppression remains unresolved. Thus, the underlying mechanism of N-(4-methoxybenzyl)-N'-(5-nitro-1,3-thiazol-2-yl)urea (AR-A014418)-elicited GSK3ß suppression in the induction of AML U937 and HL-60 cell death was investigated in this study. Our study revealed that AR-A014418-induced MCL1 downregulation remarkably elicited apoptosis of U937 cells. Furthermore, the AR-A014418 treatment increased p38 MAPK phosphorylation and decreased the phosphorylated Akt and ERK levels. Activation of p38 MAPK subsequently evoked autophagic degradation of 4EBP1, while Akt inactivation suppressed mTOR-mediated 4EBP1 phosphorylation. Furthermore, AR-A014418-elicited ERK inactivation inhibited Mnk1-mediated eIF4E phosphorylation, which inhibited MCL1 mRNA translation in U937 cells. In contrast to GSK3α, GSK3ß downregulation recapitulated the effect of AR-A014418 in U937 cells. Transfection of constitutively active GSK3ß or cotransfection of constitutively activated MEK1 and Akt suppressed AR-A014418-induced MCL1 downregulation. Moreover, AR-A014418 sensitized U937 cells to ABT-263 (BCL2/BCL2L1 inhibitor) cytotoxicity owing to MCL1 suppression. Collectively, these results indicate that AR-A014418-induced GSK3ß suppression inhibits ERK-Mnk1-eIF4E axis-modulated de novo MCL1 protein synthesis and thereby results in U937 cell apoptosis. Our findings also indicate a similar pathway underlying AR-A014418-induced death in human AML HL-60 cells.

SIRT3, PP2A and TTP protein stability in the presence of TNF-α on vincristine-induced apoptosis of leukaemia cells.

The contribution of vincristine (VCR)-induced microtubule destabilization to evoke apoptosis in cancer cells remains to be resolved. Thus, we investigated the cytotoxic mechanism of VCR on U937 and HL-60 human leukaemia cell lines. We discovered that VCR treatment resulted in the up-regulation of TNF-α expression and activation of the death receptor pathway, which evoked apoptosis of U937 cells. Moreover, VCR induced microtubule destabilization and mitotic arrest. VCR treatment down-regulated SIRT3, and such down-regulation caused mitochondrial ROS to initiate phosphorylation of p38 MAPK. p38 MAPK suppressed MID1-modulated degradation of the protein phosphatase 2A (PP2A) catalytic subunit. The SIRT3-ROS-p38 MAPK-PP2A axis inhibited tristetraprolin (TTP)-controlled TNF-α mRNA degradation, consequently, up-regulating TNF-α expression. Restoration of SIRT3 and TTP expression, or inhibition of the ROS-p38 MAPK axis increased the survival of VCR-treated cells and repressed TNF-α up-regulation. In contrast to suppression of the ROS-p38 MAPK axis, overexpression of SIRT3 modestly inhibited the effect of VCR on microtubule destabilization and mitotic arrest in U937 cells. Apoptosis of HL-60 cells, similarly, went through the same pathway. Collectively, our data indicate that the SIRT3-ROS-p38 MAPK-PP2A-TTP axis modulates TNF-α expression, which triggers apoptosis of VCR-treated U937 and HL-60 cells. We also demonstrate that the apoptotic signalling is not affected by VCR-elicited microtubule destabilization.

Autophagic HuR mRNA degradation induces survivin and MCL1 downregulation in YM155-treated human leukemia cells.

The aim of this study was to investigate the mechanism of YM155 cytotoxicity in human chronic myeloid leukemia (CML) cells. YM155-induced apoptosis of human CML K562 cells was characterized by ROS-mediated p38 MAPK activation, mitochondrial depolarization, and survivin and MCL1 downregulation. Moreover, YM155-induced autophagy caused degradation of HuR mRNA and downregulation of HuR protein expression, which resulted in destabilized survivin and MCL1 mRNA. Interestingly, survivin and MCL1 suppression contributed to autophagy-mediated HuR mRNA destabilization in YM155-treated cells. Pretreatment with inhibitors of p38 MAPK or autophagy alleviated YM155-induced autophagy and apoptosis in K562 cells, as well as YM155-induced downregulation of HuR, survivin, and MCL1. Ectopic overexpression of HuR, survivin, or MCL1 attenuated the cytotoxic effect of YM155 on K562 cells. Conversely, YM155 sensitized K562 cells to ABT-199 (a BCL2 inhibitor), and circumvented K562 cell resistance to ABT-199 because of its inhibitory effect on survivin and MCL1 expression. Overall, our data indicate that YM155-induced apoptosis is mediated by inducing autophagic HuR mRNA degradation, and reveal the pathway responsible for YM155-induced downregulation of survivin and MCL1 in K562 cells. Our findings also indicate a similar pathway underlying YM155-induced death in human CML MEG-01 cells.

Arsenic trioxide-induced p38 MAPK and Akt mediated MCL1 downregulation causes apoptosis of BCR-ABL1-positive leukemia cells.

In this study, we investigated the mechanisms underlying arsenic trioxide (ATO)-induced death of human BCR-ABL1-positive K562 and MEG-01 cells. ATO-induced apoptotic death in K562 cells was characterized by ROS-mediated mitochondrial depolarization, MCL1 downregulation, p38 MAPK activation, and Akt inactivation. ATO-induced BCR-ABL1 downregulation caused Akt inactivation but not p38 MAPK activation. Akt inactivation increased GSK3ß-mediated MCL1 degradation, while p38 MAPK-mediated NFκB activation coordinated with HDAC1 suppressed MCL1 transcription. Inhibition of p38 MAPK activation or overexpression of constitutively active Akt increased MCL1 expression and promoted the survival of ATO-treated cells. Overexpression of MCL1 alleviated mitochondrial depolarization and cell death induced by ATO. The same pathway was found to be involved in ATO-induced death in MEG-01 cells. Remarkably, YM155 synergistically enhanced the cytotoxicity of ATO on K562 and MEG-01 cells through suppression of MCL1 and survivin. Collectively, our data indicate that ATO-induced p38 MAPK- and Akt-mediated MCL1 downregulation triggers apoptosis in K562 and MEG-01 cells, and that p38 MAPK activation is independent of ATO-induced BCR-ABL1 suppression.

Compound C induces autophagy and apoptosis in parental and hydroquinone-selected malignant leukemia cells through the ROS/p38 MAPK/AMPK/TET2/FOXP3 axis.

Hydroquinone (HQ), a major metabolic product of benzene, causes acute myeloid leukemia (AML) elicited by benzene exposure. Past studies found that continuous exposure of human AML U937 cells to HQ selectively produces malignant U937/HQ cells in which FOXP3 upregulation modulates malignant progression. Other studies revealed that AMPK promotes TET2 activity on DNA demethylation and that TET2 activity is crucial for upregulating FOXP3 expression. This study was conducted to elucidate whether compound C, an AMPK inhibitor, blocked the AMPK-TET2-FOXP3 axis in AML and in HQ-selected malignant cells. We found higher levels of AMPKα, TET2, and FOXP3 expression in U937/HQ cells compared to U937 cells. Treatment of parental Original Article and HQ-selected malignant U937 cells with compound C induced ROS-mediated p38 MAPK activation, leading to a suppression of AMPKα, TET2, and FOXP3 expression. Moreover, compound C induced apoptosis and mTOR-independent autophagy. The suppression of the autophagic flux inhibited the apoptosis of compound C-treated U937 and U937/HQ cells, whereas co-treatment with rapamycin, a mTOR inhibitor, sensitized the two cell lines to compound C cytotoxicity. Overexpression of AMPKα1 or pretreatment with autophagic inhibitors abrogated compound C-induced autophagy and suppression of TET2 and FOXP3 expression. Restoration of AMPKα1 or FOXP3 expression increased cell survival after treatment with compound C. In conclusion, our results show that compound C suppresses AMPK/TET2 axis-mediated FOXP3 expression and induces autophagy-dependent apoptosis in parental and HQ-selected malignant U937 cells, suggesting that the AMPK/TET2/FOXP3 axis is a promising target for improving AML therapy and attenuating benzene exposure-induced AML progression.

Albendazole-Induced SIRT3 Upregulation Protects Human Leukemia K562 Cells from the Cytotoxicity of MCL1 Suppression.

Previous studies have shown that MCL1 stabilization confers cancer cells resistance to microtubule targeting agents (MTAs) and functionally extends the lifespan of MTA-triggered mitotically arrested cells. Albendazole (ABZ), a benzimidazole anthelmintic, shows microtubule-destabilizing activity and has been repositioned for cancer therapies. To clarify the role of MCL1 in ABZ-induced apoptosis, we investigated the cytotoxicity of ABZ on human leukemia K562 cells. Treatment with ABZ for 24 h did not appreciably induce apoptosis or mitochondrial depolarization in K562 cells, though it caused the mitotic arrest of K562 cells. ABZ-evoked p38 MAPK activation concurrently suppressed Sp1-mediated MCL1 expression and increased SIRT3 mRNA stability and protein expression. ABZ and A-1210477 (an MCL1 inhibitor) enhanced the cytotoxicity of ABT-263 (a BCL2/BCL2L1 inhibitor) to their effect on MCL1 suppression. Unlike ABZ, A-1210477 did not affect SIRT3 expression and reduced the survival of K562 cells. Overexpression of SIRT3 attenuated the A-1210477 cytotoxicity on K562 cells. ABZ treatment elicited marked apoptosis and ΔΨm loss in ABT-263-resistant K562 (K562/R) cells, but did not alter SIRT3 expression. Ectopic expression of SIRT3 alleviated the cytotoxicity of ABZ on K562/R cells. Collectively, our data demonstrate that ABZ-induced SIRT3 upregulation delays the apoptosis-inducing effect of MCL1 suppression on apoptosis induction in K562 cells.

Alleviation of palmitic acid-induced endoplasmic reticulum stress by augmenter of liver regeneration through IP3R-controlled Ca2+ release.

The aberrant release of Ca2+ from the endoplasmic reticulum (ER) contributes to the onset of ER stress, which is closely related to the pathogenesis of non-alcoholic fatty liver disease. We previously reported that augmenter of liver regeneration (ALR) alleviates ER stress and protects hepatocytes from lipotoxicity. However, the link between ALR protection and the suppression of ER stress remains unclear. In this study, we investigated whether the protection against liver steatosis afforded by ALR is related to its inhibition of calcium overflow from the ER to the mitochondria. The treatment of HepG2 cells with palmitic acid (PA) upregulated IP3R expression, triggering ER-luminal Ca2+ release and inducing ER stress. However, in ALR-transfected (ALR-Tx) HepG2 cells, PA-induced cell injury was clearly alleviated compared with that in vector-Tx cells. After exposure to PA, IP3R expression was downregulated and ER stress was effectively inhibited in the ALR-Tx cells, and ER-Ca2+ release and simultaneous mitochondrial Ca2+ uptake were lower than those in vector-Tx cells. The knockdown of ALR expression with shRNA abolished the protective effects afforded by ALR transfection. PA treatment also suppressed the interaction between BCL-2 and IP3R in HepG2 cells, whereas this interaction was massively enhanced in the ALR-Tx cells, effectively reducing the IP3R-mediated ER-Ca2+ release and thus mitochondrial Ca2+ influx. Our results suggest that the inhibition of ER stress by ALR is related to the interruption of the interaction between BCL2 and IP3R, demonstrating a novel mechanism of ER stress resistance in ALR-Tx cells.

The suppressive effect of arsenic trioxide on TET2-FOXP3-Lyn-Akt axis-modulated MCL1 expression induces apoptosis in human leukemia cells.

Arsenic trioxide (ATO) has been reported to inhibit the activity of Ten-eleven translocation methylcytosine dioxygenase (TET). TET modulates FOXP3 expression, while dysregulation of FOXP3 expression promotes the malignant progression of leukemia cells. We examined the role of TET-FOXP3 axis in the cytotoxic effects of ATO on the human acute myeloid leukemia cell line, U937. ATO-induced apoptosis in U937 cells was characterized by activation of caspase-3/-9, mitochondrial depolarization, and MCL1 downregulation. In addition, ATO-treated U937 cells showed ROS-mediated inhibition of TET2 transcription, leading to downregulation of FOXP3 expression and in turn, suppression of FOXP3-mediated activation of Lyn and Akt. Overexpression of FOXP3 or Lyn minimized the suppressive effect of ATO on Akt activation and MCL1 expression. Promoter luciferase activity and chromatin immunoprecipitation assays revealed the crucial role of Akt-mediated CREB phosphorylation in MCL1 transcription. Further, ATO-induced Akt inactivation promoted GSK3ß-mediated degradation of MCL1. Transfection of constitutively active Akt expression abrogated ATO-induced MCL1 downregulation. MCL1 overexpression lessened the ATO-induced depolarization of mitochondrial membrane and increased the viability of ATO-treated cells. Thus, our data suggest that ATO induces mitochondria-mediated apoptosis in U937 cells through its suppressive effect on TET2-FOXP3-Lyn-Akt axis-modulated MCL1 transcription and protein stabilization. Our findings also indicate that the same pathway underlies ATO-induced death in human leukemia HL-60 cells.

Membrane-damaging activities of mannosylated ovalbumin are involved in its antibacterial action.

Mannosylated ovalbumin (Man-OVA) prepared by modification of carboxyl groups with p-aminophenyl α-d-mannopyranoside shows an increase of net positive charge, which may enhance its binding to bacterial membrane. Thus, we aimed to investigate whether Man-OVA exerts antibacterial activity on Escherichia coli and Staphylococcus aureus via membrane-perturbing effect. Man-OVA inhibited the growth of E. coli and S. aureus, whereas ovalbumin (OVA) did not show any antibacterial activity. Moreover, Man-OVA induced an increase in the membrane permeability of E. coli and S. aureus, which was positively correlated to its bactericidal action. Morphological examination using scanning electron microscopy revealed that Man-OVA disrupted the bacterial membrane integrity. Destabilization of the lipopolysaccharide (LPS) layer and inhibition of lipoteichoic acid (LTA) biosynthesis in the cell wall increased the bactericidal effect of Man-OVA. In contrast to OVA, Man-OVA also induced leakage of bacterial membrane-mimicking liposomes. Color transformation of phospholipid/polydiacetylene membrane assay revealed that the membrane-interaction mode of Man-OVA was distinct from that of OVA. LPS and LTA suppressed the membrane-damaging activity of Man-OVA, whereas an increase in the Man-OVA concentration attenuated the inhibitory action of LPS and LTA. Taken together, our data indicate that the bactericidal activity of Man-OVA depends strongly on its ability to induce membrane permeability.

A Turn-on Fluorescence Sensor for Heparin Detection Based on a Release of Taiwan Cobra Cardiotoxin from a DNA Aptamer or Adenosine-Based Molecular Beacon.

This study presents two sensitive fluorescent assays for sensing heparin on the basis of the electrostatic interaction between heparin and Naja naja atra cardiotoxin 3 (CTX3). Owing to CTX3-induced folded structure of an adenosine-based molecular beacon (MB) or a DNA aptamer against CTX3, a reduction in the fluorescent signal of the aptamer or MB 5'-end labeled with carboxyfluorescein (FAM) and 3'-end labeled with 4-([4-(dimethylamino)phenyl]azo)-benzoic acid (DABCYL) was observed upon the addition of CTX3. The presence of heparin and formation of the CTX3-heparin complex caused CTX3 detachment from the MB or aptamer, and restoration of FAM fluorescence of the 5'-FAM-and-3'-DABCYL-labeled MB and aptamer was subsequently noted. Moreover, the detection of heparin with these CTX3-aptamer and CTX3-MB sensors showed high sensitivity and selectivity toward heparin over chondroitin sulfate and hyaluronic acid regardless of the presence of plasma. The limit of detection for heparin in plasma was determined to be 16 ng/mL and 15 ng/mL, respectively, at a signal-to-noise ratio of 3. This study validates the practical utility of the CTX3-aptamer and CTX3-MB systems for determining the concentration of heparin in a biological matrix.

Quinacrine induces the apoptosis of human leukemia U937 cells through FOXP3/miR-183/ß-TrCP/SP1 axis-mediated BAX upregulation.

Quinacrine, which is clinically used as an antimalarial drug, has anti-cancer activity. However, mechanism underlying its cytotoxic effect remains to be completely elucidated. In the present study, we investigated the cytotoxic effect of quinacrine on human leukemia U937 cells. Quinacrine-induced apoptosis of U937 cells was accompanied with ROS generation, mitochondrial depolarization, and BAX upregulation. Quinacrine-treated U937 cells showed ROS-mediated p38 MAPK activation and ERK inactivation, which in turn upregulated FOXP3 transcription. FOXP3-mediated miR-183 expression decreased ß-TrCP mRNA stability and suppressed ß-TrCP-mediated SP1 degradation, thus increasing SP1 expression in U937 cells. Upregulated SP1 expression further increased BAX expression. BAX knock-down attenuated quinacrine-induced mitochondrial depolarization and increased the viability of quinacrine-treated cells. Together, our data indicate that quinacrine-induced apoptosis of U937 cells is mediated by mitochondrial alterations triggered by FOXP3/miR-183/ß-TrCP/SP1 axis-mediated BAX upregulation.

Ovalbumin with Glycated Carboxyl Groups Shows Membrane-Damaging Activity.

The aim of the present study was to investigate whether glycated ovalbumin (OVA) showed novel activity at the lipid-water interface. Mannosylated OVA (Man-OVA) was prepared by modification of the carboxyl groups with p-aminophenyl α-dextro (d)-mannopyranoside. An increase in the number of modified carboxyl groups increased the membrane-damaging activity of Man-OVA on cell membrane-mimicking vesicles, whereas OVA did not induce membrane permeability in the tested phospholipid vesicles. The glycation of carboxyl groups caused a notable change in the gross conformation of OVA. Moreover, owing to their spatial positions, the Trp residues in Man-OVA were more exposed, unlike those in OVA. Fluorescence quenching studies suggested that the Trp residues in Man-OVA were located on the interface binds with the lipid vesicles, and their microenvironment was abundant in positively charged residues. Although OVA and Man-OVA showed a similar binding affinity for lipid vesicles, the lipid-interacting feature of Man-OVA was distinct from that of OVA. Chemical modification studies revealed that Lys and Arg residues, but not Trp residues, played a crucial role in the membrane-damaging activity of Man-OVA. Taken together, our data suggest that glycation of carboxyl groups causes changes in the structural properties and membrane-interacting features of OVA, generating OVA with membrane-perturbing activities at the lipid-water interface.

Carboxyl Group-Modified Myoglobin Induces TNF-α-Mediated Apoptosis in Leukemia Cells.

Previous studies have shown that chemical modification may increase the activity of proteins or confer novel activity to proteins. Some studies have indicated that myoglobin (Mb) is cytotoxic; however, the underlying mechanisms remain unclear. In this study, we investigated whether chemical modification of the carboxyl group by semicarbazide could promote the Mb cytotoxicity in human leukemia U937 cells and the underlying mechanism of semicarbazide-modified myoglobin (SEM-Mb)-induced U937 cell death. The semicarbazide-modified Mb (SEM-Mb) induced U937 cell apoptosis via the production of cleaved caspase-8 and t-Bid, while silencing of FADD abolished this effect. These findings suggest that SEM-Mb can induce U937 cell death by activating the death receptor-mediated pathway. The SEM-Mb inhibited miR-99a expression, leading to increased NOX4 mRNA and protein expression, which promoted SIRT3 degradation, and, in turn, induced ROS-mediated p38 MAPK phosphorylation. Activated p38 MAPK stimulated miR-29a-dependent tristetraprolin (TTP) mRNA decay. Downregulation of TTP slowed TNF-α mRNA turnover, thereby increasing TNF-α protein expression. The SEM-Mb-induced decrease in cell viability and TNF-α upregulation were alleviated by abrogating the NOX4/SIRT3/ROS/p38 MAPK axis or ectopic expression of TTP. Taken together, our results demonstrated that the NOX4/SIRT3/p38 MAPK/TTP axis induces TNF-α-mediated apoptosis in U937 cells following SEM-Mb treatment. A pathway regulating p38 MAPK-mediated TNF-α expression also explains the cytotoxicity of SEM-Mb in the human leukemia cell lines HL-60, THP-1, K562, Jurkat, and ABT-199-resistant U937. Furthermore, these findings suggest that the carboxyl group-modified Mb is a potential structural template for the generation of tumoricidal proteins.

Jujuboside a promotes proliferation and neuronal differentiation of APPswe-overexpressing neural stem cells by activating Wnt/ß-catenin signaling pathway.

Mobilization of hippocampal neurogenesis has been considered as a potential strategy for the treatment of neurodegenerative diseases, including Alzheimer's disease (AD). In present study, we evaluated both the neuroprotective effects and the effects on the proliferation and differentiation of APP-overexpressing neural stem cells (APP-NSCs) by Jujuboside A (JuA) in vitro. Our results demonstrated that JuA (50 µM) decreased apoptosis and suppressed oxidative stress damage of APP-NSCs. JuA (50 µM) upregulated the secretion of brain-derived neurotrophic factor and promoted the proliferation and neuronal differentiation of APP-NSCs. Moreover, JuA (50 µM) upregulated Wnt-3a and ß-catenin protein expression, and enhanced the expression of downstream genes Ccnd1, Neurod1 and Prox1. However, XAV-939, an inhibitor of the Wnt/ß-catenin signaling pathway, inhibited these positive effects of JuA. Taken together, these findings suggest that JuA promote proliferation and neuronal differentiation of APP-NSCs partly by activating the Wnt/ß-catenin signaling pathway. We hope that this study will provide a viable strategy for the treatment of AD.

Prognostic value of lncRNAs related to fatty acid metabolism in lung adenocarcinoma and their correlation with tumor microenvironment based on bioinformatics analysis.

Background: As a key regulator of metabolic pathways, long non-coding RNA (lncRNA) has received much attention for its relationship with reprogrammed fatty acid metabolism (FAM). This study aimed to investigate the role of the FAM-related lncRNAs in the prognostic management of patients with lung adenocarcinoma (LUAD) using bioinformatics analysis techniques. Methods: We obtained LUAD-related transcriptomic data and clinical information from The Cancer Genome Atlas (TCGA) database. The lncRNA risk models associated with FMA were constructed by single-sample gene set enrichment analysis (ssGSEA), weighted gene co-expression network (WGCNA), differential expression analysis, overlap analysis, and Cox regression analysis. Kaplan-Meier (K-M) and receiver operating characteristic (ROC) curves were utilized to assess the predictive validity of the risk model. Gene set variation analysis (GSVA) revealed molecular mechanisms associated with the risk model. ssGSEA and microenvironment cell populations-counter (MCP-counter) demonstrated the immune landscape of LUAD patients. The relationships between lncRNAs, miRNAs, and mRNAs were predicted by using LncBase v.2 and miRTarBase. The lncRNA-miRNA-mRNA regulatory network was visualized with Cytoscape v3.4.0. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was performed using DAVID v6.8. Quantitative real-time fluorescence PCR (qRT-PCR) was performed to verify the expression levels of the prognostic lncRNAs. Results: We identified 249 differentially expressed FMA-related lncRNAs in TCGA-LUAD, six of which were used to construct a risk model with appreciable predictive power. GSVA results suggested that the risk model may be involved in regulating fatty acid synthesis/metabolism, gene repair, and immune/inflammatory responses in the LUAD process. Immune landscape analysis demonstrated a lower abundance of immune cells in the high-risk group of patients associated with poor prognosis. Moreover, we predicted 279 competing endogenous RNA (ceRNA) mechanisms for 6 prognostic lncRNAs with 39 miRNAs and 201 mRNAs. Functional enrichment analysis indicated that the ceRNA network may be involved in the process of LUAD by participating in genomic transcription, influencing the cell cycle, and regulating tissue and organogenesis. In vitro experiments showed that prognostic lncRNA CTA-384D8.35, lncRNA RP5-1059L7.1, and lncRNA Z83851.4 were significantly upregulated in LUAD primary tumor tissues, while lncRNA RP11-401P9.4, lncRNA CTA-384D8.35, and lncRNA RP11-259K15.2 were expressed at higher levels in paraneoplastic tissues. Conclusion: In summary, the prognostic factors identified in this study can be used as potential biomarkers for clinical applications. ceRNA network construction provides a new vision for the study of LUAD pathogenesis.