Protein Kinase CK2 Promotes Proliferation, Abnormal Differentiation, and Proinflammatory Cytokine Production of Keratinocytes via Regulation of STAT3 and Akt Pathways in Psoriasis.

Protein kinase CK2 is a constitutively active and ubiquitously expressed serine/threonine kinase that is closely associated with various types of cancers, autoimmune disorders, and inflammation. However, the role of CK2 in psoriasis remains unknown. Herein, the study indicated elevated expression of CK2 in skin lesions from patients with psoriasis and from psoriasis-like mice. In the psoriasis-like mouse model, the CK2-specific inhibitor CX-4945 ameliorated imiquimod-induced psoriasis symptoms with reduced proliferation, abnormal differentiation, inflammatory cytokine production (especially IL-17A) of keratinocytes, and infiltration of γδ T cells. In in vitro studies, exogenous CK2 promoted hyperproliferation and abnormal differentiation of human keratinocytes, which were reversed by the suppression of CK2 with CX-4945 or siRNA. Furthermore, knockdown of CK2 reduced IL-17A expression and abolished IL-17A-induced proliferation and inflammatory cytokine expression in keratinocytes. Interestingly, IL-17A increased the expression of CK2 in keratinocytes, thereby establishing a positive feedback loop. In addition, suppression of CK2 inhibited the activation of STAT3 and Akt signaling pathways in human keratinocytes and imiquimod-induced psoriatic lesions of mice. These findings indicate that a highly expressed CK2 level in the skin lesions is required in the development of psoriasis by promoting epidermal hyperplasia, abnormal differentiation, and inflammatory response via regulation of the STAT3 and Akt signaling pathways. CK2 may be a target for the treatment of psoriasis.

The preprogrammed anti-inflammatory phenotypes of CD11chigh macrophages by Streptococcus pneumoniae aminopeptidase N safeguard from allergic asthma.

BACKGROUND: Early microbial exposure is associate with protective allergic asthma. We have previously demonstrated that Streptococcus pneumoniae aminopeptidase N (PepN), one of the pneumococcal components, inhibits ovalbumin (OVA) -induced airway inflammation in murine models of allergic asthma, but the underlying mechanism was incompletely determined. METHODS: BALB/c mice were pretreated with the PepN protein and exposed intranasally to HDM allergen. The anti-inflammatory mechanisms were investigated using depletion and adoptive transfer experiments as well as transcriptome analysis and isolated lung CD11chigh macrophages. RESULTS: We found pretreatment of mice with PepN promoted the proliferation of lung-resident F4/80+CD11chigh macrophages in situ but also mobilized bone marrow monocytes to infiltrate lung tissue that were then transformed into CD11high macrophages. PepN pre-programmed the macrophages during maturation to an anti-inflammatory phenotype by shaping the metabolic preference for oxidative phosphorylation (OXPHOS) and also inhibited the inflammatory response of macrophages by activating AMP-activated protein kinase. Furthermore, PepN treated macrophages also exhibited high-level costimulatory signaling molecules which directed the differentiation into Treg. CONCLUSION: Our results demonstrated that the expansion of CD11chigh macrophages in lungs and the OXPHOS metabolic bias of macrophages are associated with reduced allergic airway inflammation after PepN exposure, which paves the way for its application in preventing allergic asthma.

CD5L attenuates allergic airway inflammation by expanding CD11chigh alveolar macrophages and inhibiting NLRP3 inflammasome activation via HDAC2.

Allergic asthma is an airway inflammatory disease dominated by type 2 immune responses and there is currently no curative therapy for asthma. CD5-like antigen (CD5L) has been known to be involved in a variety of inflammatory diseases. However, the role of CD5L in allergic asthma remains unclear. In the present study, mice were treated with recombinant CD5L (rCD5L) during house dust mite (HDM) and ovalbumin (OVA) challenge to determine the role of CD5L in allergic asthma, and the underlying mechanism was further explored. Compared with PBS group, serum CD5L levels of asthmatic mice were significantly decreased, and the levels of CD5L in lung tissues and bronchoalveolar lavage fluid (BALF) were significantly increased. CD5L reduced airway inflammation and Th2 immune responses in asthmatic mice. CD5L exerted its anti-inflammatory function by increasing CD11chigh alveolar macrophages (CD11chigh AMs), and the anti-inflammatory role of CD11chigh AMs in allergic asthma was confirmed by CD11chigh AMs depletion and transfer assays. In addition, CD5L increased the CD5L+ macrophages and inhibited NLRP3 inflammasome activation by increasing HDAC2 expression in lung tissues of asthmatic mice. Hence, our study implicates that CD5L has potential usefulness for asthma treatment.

Verteporfin Inhibits Cell Proliferation and Induces Apoptosis in Human Leukemia NB4 Cells without Light Activation.

Background and Aims: Verteporfin (VP), clinically used in photodynamic therapy for neovascular macular degeneration, has recently been proven a suppressor of yes-associated protein (YAP) and has shown potential in anticancer treatment. However, its anti-human leukemia effects in NB4 cells remain unclear. In this study, we investigated the effects of VP on proliferation and apoptosis in human leukemia NB4 cells. Methods: NB4 cells were treated with VP for 24 h. The effects of VP on cell proliferation were determined using a Cell-Counting Kit-8 assay (CCK-8) assay and colony forming assay. Apoptosis and cell cycle were evaluated by flow cytometry (FCM). The protein levels were detected by western blot. Results: We found that VP inhibited the proliferation of NB4 cells in a concentration and time-dependent manner. FCM analysis showed that VP induced apoptosis in a concentration dependent manner and that VP treatment led to cell cycle arrest at G0/G1 phase. Moreover, VP significantly decreased the protein expression of YAP, p-YAP, Survivin, c-Myc, cyclinD1, p-ERK, and p-AKT. In addition, VP increased the protein expression of cleaved caspase3, cleaved PARP, Bax, and p-p38 MAPK. Conclusions: VP inhibited the proliferation and induced apoptosis in NB4 cells.

Effect of YAP Inhibition on Human Leukemia HL-60 Cells.

Background: Yes-associated protein (YAP), the nuclear effector of the Hippo pathway, is a candidate oncoprotein and participates in the progression of various malignancies. However, few reports have examined the effect of YAP inhibition in human leukemia HL-60 cells. Methods: We examined the effects of YAP knockdown or inhibition using short hairpin RNA (shRNA) or verteporfin (VP), respectively. Western blot assays were used to determine the expression levels of YAP, Survivin, cyclinD1, PARP, Bcl-2, and Bax. Cell proliferation was assessed using the cell counting kit (CCK-8) assay. Cell cycle progression and apoptosis were evaluated by flow cytometry, and apoptotic cell morphology was observed by Hoechst 33342 staining. Results: Knockdown or inhibition of YAP led to cell cycle arrest at the G0/G1 phase and increased apoptosis, inhibited cell proliferation, increased levels of Bax and cleaved PARP, and decreased levels of PARP, Bcl-2, Survivin, and cyclinD1. Moreover, Hoechst 33342 staining revealed increased cell nuclear fragmentation. Conclusion: Collectively, these results show that inhibition of YAP inhibits proliferation and induces apoptosis in HL-60 cells. Therefore, a novel treatment regime involving genetic or pharmacological inhibition of YAP could be established for acute promyelocytic leukemia.

Transcriptional regulation of TacL-mediated lipoteichoic acids biosynthesis by ComE during competence impacts pneumococcal transformation.

Competence development is essential for bacterial transformation since it enables bacteria to take up free DNA from the surrounding environment. The regulation of teichoic acid biosynthesis is tightly controlled during pneumococcal competence; however, the mechanism governing this regulation and its impact on transformation remains poorly understood. We demonstrated that a defect in lipoteichoic acid ligase (TacL)-mediated lipoteichoic acids (LTAs) biosynthesis was associated with impaired pneumococcal transformation. Using a fragment of tacL regulatory probe as bait in a DNA pulldown assay, we successfully identified several regulatory proteins, including ComE. Electrophoretic mobility shift assays revealed that phosphomimetic ComE, but not wild-type ComE, exhibited specific binding to the probe. DNase I footprinting assays revealed the specific binding sequences encompassing around 30 base pairs located 31 base pairs upstream from the start codon of tacL. Expression of tacL was found to be upregulated in the ΔcomE strain, and the addition of exogenous competence-stimulating peptide repressed the tacL transcription in the wild-type strain but not the ΔcomE mutant, indicating that ComE exerted a negative regulatory effect on the transcription of tacL. Mutation in the JH2 region of tacL upstream regulatory sequence led to increased LTAs abundance and displayed higher transformation efficiency. Collectively, our work identified the regulatory mechanisms that control LTAs biosynthesis during competence and thereby unveiled a repression mechanism underlying pneumococcal transformation.

Progranulin deficiency suppresses allergic asthma and enhances efferocytosis via PPAR-γ/MFG-E8 regulation in macrophages.

Efferocytosis can resolve airway inflammation and enhance airway tolerance in allergic asthma. While previous work has reported that progranulin (PGRN) regulated macrophage efferocytosis, but it is unclear whether PGRN-mediated efferocytosis is associated with asthma. Here, we found that in an ovalbumin (OVA)-induced allergic asthma model, the airway inflammation was suppressed and the apoptosis in lung tissues was ameliorated in PGRN-deficient mice. In contrast, PGRN knockdown in human bronchial epithelial cells increased apoptosis in vitro. Furthermore, PGRN-deficient macrophages had significantly stronger efferocytosis ability than wild type (WT) macrophages both in vitro and in vivo. PGRN-deficient peritoneal macrophages (PMs) exhibited increased expression of genes associated with efferocytosis including milk fat globule-epidermal growth factor 8 (MFG-E8), peroxisome proliferator-activated receptor gamma (PPAR-γ) and sirtuin1 (SIRT1) and increased capacity to produce the anti-inflammatory mediator interleukin (IL)-10 during efferocytosis. GW9662, the inhibitor of PPAR-γ, abolished increased efferocytosis and MFG-E8 expression in PGRN-deficient PMs suggesting that PGRN deficiency enhanced MFG-E8-mediated efferocytosis through PPAR-γ. Correspondingly, efferocytosis genes were increased in the lungs of OVA-induced PGRN-deficient mice. GW9662 treatment reduced MFG-E8 expression but did not significantly affect airway inflammation. Our results demonstrated that PGRN deficiency enhanced efferocytosis via the PPAR-γ/MFG-E8 pathway and this may be one of the reasons PGRN deficiency results in inhibition of airway inflammation in allergic asthma.

IL-27 mediates immune response of pneumococcal vaccine SPY1 through Th17 and memory CD4+T cells.

Vaccination is an effective means of preventing pneumococcal disease and SPY1 is a live attenuated pneumococcal vaccine we obtained earlier. We found IL-27 and its specific receptor (WSX-1) were increased in SPY1 vaccinated mice. Bacterial clearance and survival rates were decreased in SPY1 vaccinated IL-27Rα-/- mice. The vaccine-induced Th17 cell response and IgA secretion were also suppressed in IL-27Rα-/- mice. STAT3 and NF-κB signaling and expression of the Th17 cell polarization-related cytokines were also decreased in IL-27Rα-/- bone-marrow-derived dendritic cells(BMDC) stimulated with inactivated SPY1. The numbers of memory CD4+T cells were also decreased in SPY1 vaccinated IL-27Rα-/- mice. These results suggested that IL-27 plays a protective role in SPY1 vaccine by promoting Th17 polarization through STAT3 and NF-κB signaling pathways and memory CD4+T cells production in the SPY1 vaccine. In addition, we found that the immune protection of SPY1 vaccine was independent of aerobic glycolysis.

Elevated Serum Levels of Progranulin and Soluble Vascular Cell Adhesion Molecule-1 in Patients with COVID-19.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with the angiocentric inflammation and angiogenesis, yet the molecules involved in this process remain to be determined. METHODS: We did a cross-sectional study of a cohort of patients with COVID-19 in Zunyi, China between February 1 and March 30, 2020. Serum concentrations of PGRN were determined by enzyme-linked immunosorbent assay in patients with COVID-19 at hospital admission and at discharge. In parallel, the serum levels of soluble adhesion molecules, vascular cell adhesion molecule-1 (sVCAM-1), intercellular adhesion molecule-1 (sICAM-1), P-selectin (sP-selectin), and E-selectin (sE-selectin) were assayed by a human adhesion molecule multiplex kit. The association between serum PGRN levels and other laboratory test results was analyzed by Spearman correlation analysis. RESULTS: At baseline, the median serum PGRN levels in patients with COVID-19 were 94.8 ng/mL [interquartile range (IQR): 66.6-119.6 ng/mL], which was significantly elevated compared with those in healthy controls (46.3 ng/mL, IQR: 41.8-55.6 ng/mL). Moreover, the median serum sVCAM-1 levels were significantly higher in COVID-19 patients (1396.0 ng/mL, IQR: 1019.1-1774.8 ng/mL) than those in healthy controls (612.4 ng/mL, IQR: 466.4-689.3 ng/mL). However, the levels of sICAM-1, sP-selectin, and sE-selectin were not significantly elevated in patients with COVID-19 when compared to healthy controls. Further analysis showed that serum PGRN levels were significantly positively associated with sVCAM-1 (r= 0.675, P= 0.008) and inversely with sICAM-1 (r= -0.609, P= 0.021) and aspartate aminotransferase levels (r= -0.560, P= 0.037) in patients with COVID-19 at hospital admission. In COVID-19 patients, serum PGRN and sVCAM-1 levels fell significantly after successful treatment. CONCLUSION: The present study demonstrates elevated serum PGRN and sVCAM-1 levels in patients with COVID-19, which may provide clues as to the mechanisms underlying the pathogenesis of COVID-19. Further studies are warranted to evaluate the potential of PGRN and sVCAM-1 as biomarkers and investigate their role in the pathogenesis of COVID-19.

Molecular Epidemiology and Clinical Features of Enteroviruses-Associated Hand, Foot, and Mouth Disease and Herpangina Outbreak in Zunyi, China, 2019.

Background: Hand, foot and mouth disease (HFMD) and herpangina (HA), two of the most common childhood infectious diseases, are associated with enteroviruses (EVs) infection. The aim of this study was to identify the molecular epidemiology of enterovirus causing HFMD/HA in Zunyi, China, during 2019, and to describe the clinical features of the cases. Methods: We collected the information on demographic and clinical characteristics, laboratory data of laboratory-confirmed EVs associated HFMD/HA cases in Zunyi Medical University Third Affiliated Hospital between March 1 and July 31, 2019. EV types were determined by either one-step real time RT-PCR or partial VP1 gene sequencing and sequence alignment. Phylogenetic analysis of CVA6, CVA2, and CVA5 were established based on the partial VP1 gene sequences by neighbor-joining method. Differences in clinical characteristics and laboratory results of the cases were compared among patients infected with the most prevalent EV types. Results: From 1 March to 31 July 2019, 1,377 EVs associated HFMD/HA inpatients were confirmed. Of them, 4 (0.3%, 4/1,377) were EV-A71-associated cases, 84 (6.1%, 84/1,377) were CVA16-associated cases, and 1,289 (93.6%, 1,289/1,377) were non-EV-A71/CVA16-associated cases. Of the randomly selected 372 non-EV-A71/CVA16 cases, EV types have been successfully determined in 273 cases including 166 HFMD and 107 HA cases. For HFMD cases, the three most common types were CVA6 (80.7%, 134/166), CVA2 (5.4%, 9/166) and CVA5 (3.0%, 5/166); similarly, for HA cases, the three most prevalent serotypes were CVA6 (36.5%, 39/107), CVA2 (21.5%, 23/107) and CVA5 (18.7%, 20/107). Phylogenetic analysis showed that subclade D of CVA5, and subclade E of CVA6 and CVA2 were predominant in Zunyi during the outbreak in 2019. Compared with the cases caused by CVA16, the incidence of high fever and severe infection associated with CVA2, CVA5, and CVA6 was higher. Conclusions: The recent HFMD/HA outbreak in Zunyi is due to a larger incidence of CVA6, CVA2, and CVA5. Novel diagnostic reagents and vaccines against these types would be important to monitor and control EV infections.

Prevalence and clinical significance of common respiratory pathogens in the upper respiratory tract of children with community-acquired pneumonia in Zunyi, China.

PURPOSE: To estimate the prevalence of common respiratory pathogens among children with community-acquired pneumonia (CAP) in Zunyi City, Guizhou, China, and to assess whether the presence of common respiratory pathogens in patients is associated with disease severity. PATIENTS AND METHODS: This retrospective study assessed the prevalence of common respiratory viruses and bacteria in the upper respiratory tract of among infants and children aged 1 month to 5 years hospitalized with radiologically confirmed CAP between April 2017 and March 2018. Direct immunofluorescence assay and bacterial culture were used to identify viruses and bacteria in the upper airway specimens, respectively. The association between severe CAP and the presence of pathogens was determined using multivariate logistic regression models. RESULTS: Of the 685 patients enrolled, 583 cases had viral and/or bacterial pathogens detected, which included the presence of only viral pathogens, only bacterial pathogens, and mixed viral and bacterial pathogens in 34.3%, 29.7%, and 36.0% of cases, respectively. Respiratory syncytial virus (RSV) was the most common viral pathogen, with a prevalence rate of 39.9% (273/685). Haemophilus influenzae was the most commonly detected bacterial pathogen, with a prevalence rate of 15.3% (105/685). The presence of RSV (adjusted odds ratio [aOR], 1.9; 95% confidence interval [CI], 1.3-2.8) and Staphylococcus aureus (aOR, 13.7; 95% CI, 5.5-33.9) in children with CAP was associated with severe pneumonia. CONCLUSIONS: In a cohort of Zunyi infants and children hospitalized with CAP, RSV was the most common pathogen.

MiR-15b regulates cell differentiation and survival by targeting CCNE1 in APL cell lines.

MicroRNAs have been shown to be involved in various cell processes, including proliferation, apoptosis and differentiation. However, little is known about their function in granulopoiesis. In the present study, overexpression and knockdown experiments revealed that miR-15b was required to block the proliferation of NB4 and HL60 cells and induce them differentiated to granulocyte lineage. Moreover, we identified CCNE1 as a direct target of miR-15b, and demonstrated that CCNE1 was involved in cell differentiation and proliferation in acute promyelocytic leukemia cells. In addition, we demonstrated a novel pathway in which miR-15b regulated cells arrested in the G0/G1 phase and promoted terminal differentiation of cells by targeting CCNE1, which could modulate the cell cycle effort pRb in APL cells. These events blocked cell proliferation and promoted granulocyte differentiation. In conclusion, our data highlighted, for the first time, the important role of miR-15b in myeloid differentiation and suggested the potential role of miR-15b in cancer therapy.

RAS-Responsive Element-Binding Protein 1 Blocks the Granulocytic Differentiation of Myeloid Leukemia Cells.

RAS-responsive element-binding protein 1 (RREB1) is a transcription factor that is implicated in RAS signaling and multiple tumors. However, the role of RREB1 in acute myeloid leukemia has not been studied. We found that RREB1 is overexpressed in AML patients and myeloid leukemia cell lines (NB4 and HL-60), and RREB1 expression was significantly decreased during granulocytic differentiation of myeloid leukemia cells induced by all-trans retinoic acid (ATRA). Then we performed a RREB1 knockdown assay in NB4 and HL-60 cells; the results showed that knockdown of RREB1 upregulated expression of CD11b, CEBPß, and microRNA-145 (miR-145), which hinted that knockdown of RREB1 enhanced granulocytic differentiation of myeloid leukemia cells. In addition, inhibitor of miR-145 can offset the enhanced effect on granulocytic differentiation mediated by downregulation of RREB1. These collective findings demonstrated that RREB1 blocks granulocytic differentiation of myeloid leukemia cells by inhibiting the expression of miR-145 and downstream targets of the RAS signal pathway. These may provide a promising therapeutic target for AML patients.

ACTL6A interacts with p53 in acute promyelocytic leukemia cell lines to affect differentiation via the Sox2/Notch1 signaling pathway.

Actin-like 6A (ACTL6A), a component of BAF chromatin remodeling complexes, is important for cell differentiation. Nevertheless, its role and mechanism in acute promyelocytic leukemia (APL) has not been reported. To identify the genes that may participate in the development of APL, we analyzed data from an APL cDNA microarray (GSE12662) in the NCBI database, and found that ACTL6A was up-regulated in APL patients. Subsequently, we investigated the function and mechanisms of ACTL6A in myeloid cell development. The expression of ACTL6A was gradually decreased during granulocytic differentiation in all-trans retinoic acid-treated NB4 and HL-60 cells, and phorbol myristate acetate-treated HL-60 cells. We also found that knockdown of ACTL6A promoted differentiation in NB4 and HL-60 cells, and decreased the levels of Sox2 and Notch1. Mechanistically, ACTL6A interacted with and was co-localized with Sox2 and p53. Meanwhile, CBL0137, an activator of p53, decreased the expression of ACTL6A and promoted differentiation in NB4 and HL-60 cells. These findings suggest that the inhibition of ACTL6A promotes differentiation via the Sox2 and Notch1 signaling pathways. Furthermore, the differentiation promoted by inhibiting ACTL6A could be regulated by p53 via its physical interaction with ACTL6A.

miR-382-5p modulates the ATRA-induced differentiation of acute promyelocytic leukemia by targeting tumor suppressor PTEN.

In acute promyelocytic leukemia (APL), all-trans retinoic acid (ATRA) treatment induces granulocytic differentiation and maturation. MicroRNAs play pivotal roles in formation of the leukemic phenotype. Previously, microRNA-382-5p (miR-382-5p) was upregulated in acute myeloid leukemia (AML) with t(15;17). In the present study, we found that miR-382-5p expression was elevated with ATRA-induced differentiation of APL. To investigate the potential functional role of miR-382-5p in APL differentiation, an APL cell line was transfected with miR-382-5p mimics, inhibitors, or negative control (NC). The results showed in APL cell line NB4 that miR-382-5p downregulation upon ATRA treatment was a key event in the drug response. Mechanistic investigations revealed that miR-382-5p targeted the ATRA-regulated tumor suppressor gene PTEN through direct binding to its 3' UTR. Enforced expression of miR-382-5p or specific PTEN inhibitors inhibited ATRA-induced granulocytic differentiation via regulation of the cell cycle regulator cyclinD1. Conversely, PTEN overexpression promoted differentiation and enhanced sensitivity of NB4 cell line to physiological levels of ATRA. Finally, we found that PTEN overexpression restored PML nuclear bodies (NBs). Taken together, these results demonstrated that up-regulated miR-382-5p in NB4 cell line inhibited granulocytic differentiation through the miR-382-5p/PTEN axis, uncovering PTEN as a critical element in the granulocytic differentiation program induced by ATRA in APL.

Salinomycin induces apoptosis and differentiation in human acute promyelocytic leukemia cells.

At present, acute promyelocytic leukemia (APL) is the most curable form of acute myeloid leukemia and can be treated using all-trans retinoic acid and arsenic trioxide. However, the current treatment of APL is associated with some issues such as drug toxicity, resistance and relapse. Therefore, other strategies are necessary for APL treatment. In the present study, we investigated the effects of salinomycin (SAL) on APL cell lines NB4 and HL-60 and determined its possible mechanisms. We observed that SAL inhibited cell proliferation, as determined by performing Cell Counting Kit-8 (CCK-8) assay, promoted cell apoptosis, as determined based on morphological changes, and increased Annexin V/propidium iodide (PI)-positive apoptotic cell percentage. Treatment with SAL increased Bax/Bcl-2 and cytochrome c expression and activated caspase-3 and -9, thus leading to poly(ADP-ribose) polymerase (PARP) cleavage and resulting in cell apoptosis. These results revealed that SAL induced cell apoptosis through activation of the intrinsic apoptosis pathway. The present study is the first to show that SAL induced the differentiation of APL cells, as determined based on mature morphological changes, increased NBT-positive cell and CD11b-positive cell percentages and increased CD11b and C/EBPß levels. Furthermore, SAL decreased the expression of ß-catenin and its targets cyclin D1 and C-myc. Results of immunofluorescence analysis revealed that SAL markedly decreased the ß-catenin level in both the nucleus and cytoplasm. Combination treatment with SAL and IWR-1, an inhibitor of Wnt signaling, synergistically triggered SAL-induced differentiation of APL cells. These findings demonstrated that SAL effectively inhibited cell proliferation accompanied by induction of apoptosis and promotion of cell differentiation by inhibiting Wnt/ß-catenin signaling. Collectively, these data revealed that SAL is a potential drug for treatment of APL.

Effects of lapatinib on cell proliferation and apoptosis in NB4 cells.

Acute promyelocytic leukemia (APL), characterized by the presence of the promyelocytic leukemia (PML)-retinoic acid α receptor (RARα) fusion protein, responds to treatment with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). However, drug resistance and side effects restrict the application of these reagents. Hence, the development of novel therapeutic drugs for APL treatment is critical. Lapatinib, a small-molecule tyrosine kinase inhibitor, has been used in the treatment of different tumors. However, it is unclear whether lapatinib exerts antitumor effects on APL. The present study investigated the antitumor effects and potential mechanisms of lapatinib on NB4 cells derived from APL. Cell Counting Kit-8 assay and colony forming analysis indicated that lapatinib inhibited NB4 cell proliferation in a dose-dependent manner. Flow cytometry analysis revealed that lapatinib induced cell cycle arrest at the S phase and promoted cell apoptosis. Furthermore, Liu's staining and Hoechst 33258 staining revelaed that lapatinib treatment induced an apoptotic nuclear phenomenon. Furthermore, lapatinib induced apoptosis by decreasing Bcl-2 and PML-RARα levels, and by increasing the levels of Bax, cleaved PARP, cleaved caspase-3 and cleaved caspase-9. In addition, lapatinib increased the levels of phospho-p38 MAPK and phospho-JNK, and decreased the levels of phospho-Akt. The p38 inhibitor PD169316 partially blocked lapatinib-induced proliferation inhibition and apoptosis, whereas the JNK inhibitor SP600125 had no such effects. Therefore, treatment with lapatinib may be a promising strategy for APL therapy.

Epigallocatechin-3-gallate promotes all-trans retinoic acid-induced maturation of acute promyelocytic leukemia cells via PTEN.

Acute promyelocytic leukemia (APL) is a distinctive subtype of acute myeloid leukemia (AML) in which the hybrid protein promyelocytic leukemia protein/retinoic acid receptor α (PML/RARα) acts as a transcriptional repressor impairing the expression of genes that are critical to myeloid cell mutation. We aimed at explaining the molecular mechanism of green tea polyphenol epigallocatechin-3-gallate (EGCG) enhancement of ATRA-induced APL cell line differentiation. Tumor suppressor phosphatase and tensin homolog (PTEN) was found downregulated in NB4 cells and rescued by proteases inhibitor MG132. A significant increase of PTEN levels was found in NB4, HL-60 and THP-1 cells upon ATRA combined with EGCG treatment, paralleled by increased myeloid differentiation marker CD11b. EGCG in synergy with ATRA promote degradation of PML/RARα and restores PML expression, and increase the level of nuclear PTEN. Pretreatment of PTEN inhibitor SF1670 enhances the PI3K signaling pathway and represses NB4 cell differentiation. Moreover, the induction of PTEN attenuated the Akt phosphorylation levels, pretreatment of PI3K inhibitor LY294002 in NB4 cells, significantly augmented the cell differentiation and increased the expression of PTEN. These results therefore indicate that EGCG targets PML/RARα oncoprotein for degradation and potentiates differentiation of promyelocytic leukemia cells in combination with ATRA via PTEN.

[Mechanism underlying inhibition of proliferation and promotion of apoptosis by lapatinib in HL60 cells].

Objective To investigate the effect of lapatinib on cell proliferation and apoptosis in acute myeloid leukemia HL60 cells in vitro and the related molecular mechanisms. Methods The HL60 cells were treated with 5, 10, 15 µmol/L lapatinib for 24 hours, and then morphological changes of the cells were observed under optical microscope. CCK-8 assay was used to assess the cell viability. Colony formation assay was performed to detect the cell proliferation ability. Cell apoptosis labeled by annexinV-FITC/PI were analyzed by flow cytometry. Wright modified LIU's staining and Hoechst33342 fluorescent staining were used to observe the morphology of the nucleus. Western blotting was utilized to detect the expressions of Bax, Bcl2, caspase-3, caspase-9, cleaved caspase-3, cleaved caspase-9, cleaved poly-ADP-ribose polymerase (cleaved PARP), cell proliferation regulating inhibitor of protein phosphatase 2A (CIP2A), c-MYC, AKT and p-AKT. Results Compared with the control group, lapatinib inhibited cell proliferation and promoted apoptosis, induced nuclear fragmentation, chromatin condensation of HL60 cells in a dose-dependent manner. Meanwhile, it down-regulated the expression of Bcl2, up-regulated the levels of Bax, cleaved caspase-3, cleaved caspase-9 and cleaved PARP, and decreased the levels of CIP2A, p-AKT and c-MYC. Conclusion Lapatinib could inhibit cell proliferation and promote apoptosis in HL60 cells by inhibiting the CIP2A/AKT/c-MYC signal pathway.

[Effect of drought on photosynthetic characteristics and growth of Jatropha curcas seedlings under different nitrogen levels].

A pot experiment with controlled water supply was conducted to study the effects of drought stress (continuous drought for 0 d, 5 d, 10 d, ... 45 d) on the photosynthetic characteristics and growth of Jatropha curcas seedlings under different nitrogen fertilization levels (N0, 0 kg N x hm(-2); N(L), 96 kg N x hm(-2; N(M), 288 kg N x hm(-2); N(H), 480 kg N x hm(-2)). With the enhancement of drought stress, the leaf relative water content (RWC1), height growth (Z(h)), basal diameter growth (Z(d), leaf area (L(a)), net photosynthetic rate ( P(n)), transpiration rate (T(r)), and stomatal conductance (G(s)) decreased significantly (P < 0.01), irrespective of nitrogen fertilization level. The chlorophyll (Chl) content and water use efficiency (WUE) increased first and decreased then, while the intercellular CO2, concentration (C(i)) had an increase after an initial decrease. Under adequate water condition, nitrogen fertilization promoted the photosynthesis and growth of J. curcas seedlings to different degrees, and the effect was increased with increasing nitrogen fertilization level. Under drought stress, the effects of nitrogen nutrition on the photosynthesis and growth were dependent on drought intensity and nitrogen fertilization level. Specifically, increasing nitrogen fertilization level could promote the photosynthesis and growth of J. curcas seedlings under mild drought, the promotion effect of N(M) was higher than that of N(L) and N(H) under moderate drought, and N(L) had the best promotion effect while N(H) weakened the effect or made it negative under severe drought.