Hainanenin-1, an oncolytic peptide, triggers immunogenic cell death via STING activation in triple-negative breast cancer.

BACKGROUND: In triple-negative breast cancer (TNBC) therapy, insufficient tumor infiltration by lymphocytes significantly hinders the efficacy of immune checkpoint inhibitors. We have previously demonstrated that Hainanenin-1 (HN-1), a host defense peptide (HDP) identified from Hainan frog skin, induces breast cancer apoptosis and boots anti-tumor immunity via unknown mechanism. METHODS: We used in vitro experiments to observe immunogenic cell death (ICD) indicators in HN-1-treated TNBC cell lines, a mouse tumor model to verify HN-1 promotion of mice anti-tumor immune response, and an in vitro drug sensitivity test of patient-derived breast cancer cells to verify the inhibitory effect of HN-1. RESULTS: HN-1 induced ICD in TNBC in a process during which damage-associated molecular patterns (DAMPs) were released that could further increase the anti-tumor immune response. The secretion level of interleukin 2 (IL-2), IL-12, and interferon γ in the co-culture supernatant was increased, and dendritic cells (DCs) were activated via a co-culture with HN-1-pretreated TNBC cells. As a result, HN-1 increased the infiltration of anti-tumor immune cells (DCs and T lymphocytes) in the mouse model bearing both 4T1 and EMT6 tumors. Meanwhile, regulatory T cells and myeloid-derived suppressor cells were suppressed. In addition, HN-1 induced DNA damage, and double-strand DNA release in the cytosol was significantly enhanced, indicating that HN-1 might stimulate ICD via activation of STING pathway. The knockdown of STING inhibited HN-1-induced ICD. Of note, HN-1 exhibited inhibitory effects on patient-derived breast cancer cells under three-dimensional culture conditions. CONCLUSIONS: Collectively, our study demonstrated that HN-1 could be utilized as a potential compound that might augment immunotherapy effects in patients with TNBC.

Transcriptional regulations of pollen tube reception are associated with the fertility of the ginger species Zingiber zerumbet and Zingiber corallinum.

Zingiber zerumbet and Zingiber corallinum are economically valuable species in the genus Zingiber. While Z. corallinum is sexually active, Z. zerumbet adopts clonal propagation, although it has the potential for sexual reproduction. It is unclear so far at which step during the sexual reproduction of Z. zerumbet inhibition occurs, and what are the regulatory mechanisms underlying this inhibition. Here, by comparing with the fertile species Z. corallinum using microscopy-based methods, we show that rare differences were observed in Z. zerumbet up to the point when the pollen tubes invaded the ovules. However, a significantly higher percentage of ovules still contained intact pollen tubes 24 h after pollination, suggesting pollen tube rupture was impaired in this species. Further RNA-seq analysis generated accordant results, showing that the transcription of ANX and FER, as well as genes for the partners in the same complexes (e.g., BUPS and LRE, respectively), and those putative peptide signals (e.g., RALF34), were timely activated in Z. corallinum, which ensured the pollen tubes being able to grow, reorient to ovules, and receipt by embryo sacs. In Z. zerumbet, genes for these complexes were cooperatively suppressed, which would result in the maintenance of PT integrity due to the disruption of RALF34-ANX/BUPS signaling in PT and the failure of PT reception by an active synergid due to the insufficiency of the synergid-harbored FER/LRE complex. Taking the results from the cytological and RNA-seq studies together, a model is proposed to illustrate the possible regulation mechanisms in Z. zerumbet and Z. corallinum, in which the regulations for pollen tube rupture and reception are proposed as the barrier for sexual reproduction in Z. zerumbet.

A novel ferroptosis-related genes model for prognosis prediction of lung adenocarcinoma.

BACKGROUND: Ferroptosis is a newly discovered form of cell death characterized by iron-dependent lipid peroxidation. This study aims to investigate the potential correlation between ferroptosis and the prognosis of lung adenocarcinoma (LUAD). METHODS: RNA-seq data were collected from the LUAD dataset of The Cancer Genome Atlas (TCGA) database. Based on ferroptosis-related genes, differentially expressed genes (DEGs) between LUAD and paracancerous specimens were identified. The univariate Cox regression analysis was performed to screen key genes associated with the prognosis of LUAD. LUAD patients were divided into the training set and validation set. Then, we screened out key genes and built a prognostic prediction model involving 5 genes using the least absolute shrinkage and selection operator (LASSO) regression with tenfold cross-validation and the multivariate Cox regression analysis. After dividing LUAD patients based on the median level of risk score as cut-off value, the generated prognostic prediction model was validated in the validation set. Moreover, we analyzed the somatic mutations, and estimated the scores of immune infiltration in the high-risk and low-risk groups. Functional enrichment analysis of DEGs was performed as well. RESULTS: High-risk scores indicated the worse prognosis of LUAD. The maximum area under curve (AUC) of the training set and the validation set in this study was 0.7 and 0.69, respectively. Moreover, we integrated the age, gender, and tumor stage to construct the composite nomogram. The charts indicated that the AUC of LUAD cases with the survival time of 1, 3 and 5 years was 0.698, 0.71 and 0.73, respectively. In addition, the mutation frequency of LUAD patients in the high-risk group was significantly higher than that in the low-risk group. Simultaneously, DEGs were mainly enriched in ferroptosis-related pathways by analyzing the functional results. CONCLUSIONS: This study constructs a novel LUAD prognosis prediction model involving 5 ferroptosis-related genes, which can be used as a promising tool for decision-making of clinical therapeutic strategies of LUAD.

Oleandrin, a cardiac glycoside, induces immunogenic cell death via the PERK/elF2α/ATF4/CHOP pathway in breast cancer.

Chemotherapeutic agents have been linked to immunogenic cell death (ICD) induction that is capable of augmenting anti-tumor immune surveillance. The cardiac glycoside oleandrin, which inhibits Na+/K+-ATPase pump (NKP), has been shown to suppress breast cancer growth via inducing apoptosis. In the present study, we showed that oleandrin treatment triggered breast cancer cell ICD by inducing calreticulin (CRT) exposure on cell surface and the release of high-mobility group protein B1 (HMGB1), heat shock protein 70/90 (HSP70/90), and adenosine triphosphate (ATP). The maturation and activation of dendritic cells (DCs) were increased by co-culturing with the oleandrin-treated cancer cells, which subsequently enhanced CD8+ T cell cytotoxicity. Murine breast cancer cell line EMT6 was engrafted into BALB/c mice, and tumor-bearing mice were administered with oleandrin intraperitoneally every day. Oleandrin inhibited tumor growth and increased tumor infiltrating lymphocytes including DCs and T cells. Furthermore, the differential mRNA expression incurred by oleandrin was investigated by mRNA sequencing and subsequently confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Mechanistically, oleandrin induced endoplasmic reticulum (ER) stress-associated, caspase-independent ICD mainly through PERK/elF2α/ATF4/CHOP pathway. Pharmacological and genetic inhibition of protein kinase R-like ER kinase (PERK) suppressed oleandrin-triggered ICD. Taken together, our findings showed that oleandrin triggered ER stress and induced ICD-mediated immune destruction of breast cancer cells. Oleandrin combined with immune checkpoint inhibitors might improve the efficacy of immunotherapy.

Oleandrin induces apoptosis via activating endoplasmic reticulum stress in breast cancer cells.

BACKGROUND: Breast cancer is the most common malignant tumor in women. Due to limited treatment outcome and high rate of metastasis, the prognosis is especially poor for triple-negative breast cancer. It is urgent to discover and develop novel agents for treatment of breast cancer. Herein, we investigated the potential mechanisms of Oleandrin's (a cardiac glycoside) cytotoxic activity against breast cancer cells. METHODS: Cell proliferation was assessed by xCELLigence Real-Time Cell Analyzer (RTCA)-MP system. Apoptotic cells were detected by using Annexin V/PI staining and nuclear fragments observation. The effect of oleandrin on ATP1B3 expression and markers of ER stress were determined by western blot. A primary cell sensitivity assay was performed via a collagen gel droplet-embedded culture drug sensitivity method (CD-DST). RESULTS: Oleandrin suppressed cell proliferation and colony formation in the three breast cancer cell lines but did not affect normal mammary epithelial cells. Additionally, the expression of ATP1B3 was higher in the three breast cancer cell lines compared to MCF10A cells. Treatment with oleandrin increased the number of apoptotic cells and led to nuclear pyknosis, fragmentation, and apoptotic body formation in breast cancer cells. Furthermore, oleandrin treatment increased expression of Bax and Bim but decreased that of Bcl-2. Treatment with oleandrin also upregulated the expression of endoplasmic reticulum stress associated proteins, including eIF2α, ATF4, and CHOP, but not PERK. oleandrin treatment also induced the phosphorylation of PERK and eIF2α. Of note, oleandrin exhibited antitumor effects on patient-derived breast cancer cells under three-dimensional culture conditions. CONCLUSIONS: Taken together, our results suggest that oleandrin induces mitochondrial-mediated apoptosis by activating endoplasmic reticulum stress in breast cancer. Moreover, oleandrin may be an effective strategy for the treatment of breast cancer.

EX527, a Sirt-1 inhibitor, induces apoptosis in glioma via activating the p53 signaling pathway.

Sirtuin-1 (Sirt-1), an NAD-dependent deacetylase, promotes tumorigenesis in glioma; however, whether the Sirt-1 specific inhibitor, EX527 exerts antitumor effects and the underlying mechanism in glioma requires further investigation. In the present study, the proliferative and colony formation abilities of two glioma cell lines (U87MG and LN-299) were inhibited by EX527. Treatment with EX527 increased the number of apoptotic cells (Annexin V-fluorescein isothiocyanate/propidium iodide); pretreatment with the caspase inhibitor Z-VAD-FMK suppressed EX527-induced apoptosis, suggesting that EX527 induced caspase-dependent apoptosis. In addition, western blotting revealed that EX527 treatment increased the expression of cleaved-caspase-3, poly (ADP-ribose) polymerase-1, B-cell lymphoma 2 (Bcl-2)-associated-X-protein and Bcl-2-like 11 but decreased that of Bcl-2. p53 is deacetylated by Sirt-1, attenuating its function. Furthermore, EX527 upregulated the expression of p53, acetylated p53 and the p53 target gene p21. This result suggests that EX527 induced cell apoptosis by activating p53 in glioma. Of note, EX527 exhibited antitumor effects on patient-derived glioma cells under three-dimensional culture conditions. Collectively, the results of the present study indicated that EX527 may be used as an effective compound in the treatment of glioma.

Vacquinol­1 induces apoptosis in hepatocellular carcinoma cell.

Vacquinol­1 (Vacq), a quinolone derivative, has recently been reported to display potent antitumor effects in glioblastomas by inducing cellular massive vacuolization and cell death. However, whether Vacq induces cytotoxicities in other types of cancers, and the potential underlying mechanism, remain to be investigated. In the present study, it was revealed that Vacq suppressed cell growth and colony formation in the hepatocellular carcinoma (HCC) cell lines BEL7402 and Huh7. In addition, treatment with Vacq increased the number of early and late apoptotic cells as assessed by flow cytometry with fluorescein isothiocyanate­conjugated Annexin V and propidium iodide double staining. Notably, the effect by Vacq in the tested cells could be inhibited by pretreatment with a broad specificity caspase inhibitor Z­VAD­FMK, suggesting that Vacq may induce apoptosis in HCC cells. Morphologically, exposure to Vacq resulted in nuclear fragmentation and the apoptotic body formation in HCC cells. Furthermore, Vacq treatment increased the cleavage of caspase­3, caspase­9 and poly(adenosine diphosphate­ribose) polymerase­1. Mechanistic analysis revealed that Vacq upregulated the expressions of pro­apoptotic proteins [B­cell lymphoma 2 (bcl­2)­associated X protein (Bax) and Bcl­2­like protein 11] and downregulated the pro­survival protein, Bcl­2, expression in HCC cells. Furthermore, Vacq induced Bax translocation. Of note, Vacq displayed inhibitory effects on patient­derived HCC cells in two­dimensional (2D) and three-dimensional (3D) cultures. Taken together, the data suggested that Vacq induced intrinsic apoptosis and may be utilized as an effective reagent for HCC treatment.

Mesenteric lymph nodes contribute to proinflammatory Th17-cell generation during inflammation of the small intestine in mice.

T cells of the small intestine, including Th17 cells, are critically involved in host protection from microbial infection, and also contribute to the pathogenesis of small bowel inflammatory disorders. Accumulating evidence suggests that mesenteric lymph nodes (MLNs) play important roles in gut-tropic T-cell generation, although it is still unclear if MLNs are involved in the pathogenesis of small intestine inflammation. To address this issue, we analyzed the roles of both MLNs and Peyer's patches (PPs) by evaluating MLN- or PP-deficient mice in an experimental model of small intestine inflammation, induced by CD3-specific mAb injection. Interestingly, MLNs, but not PPs, were essential for the pathogenesis of intestinal inflammation, in particular the accumulation and infiltration of CD4(+) T-cell populations, including Th17 cells, from the blood. In addition, CD4(+) T-cell accumulation was dependent on the function of the α4 ß7 integrin. Furthermore, MLN removal led to a significantly reduced number of peripheral α4 ß7 (+) CD4(+) effector memory T cells under normal conditions, suggesting that MLNs may play a role in maintaining the number of gut-tropic CD4(+) effector memory T cells circulating in the blood. Taken together, the present study highlights the important role of MLNs in contributing to the pathogenesis of small intestine inflammation.

OX40 and IL-7 play synergistic roles in the homeostatic proliferation of effector memory CD4⁺ T cells.

T-cell homeostasis preserves the numbers, the diversity and functional competence of different T-cell subsets that are required for adaptive immunity. Naïve CD4(+) T (TN ) cells are maintained in the periphery via the common γ-chain family cytokine IL-7 and weak antigenic signals. However, it is not clear how memory CD4(+) T-cell subsets are maintained in the periphery and which factors are responsible for the maintenance. To examine the homeostatic mechanisms, CFSE-labeled CD4(+) CD44(high) CD62L(low) effector memory T (TEM ) cells were transferred into sublethally-irradiated syngeneic C57BL/6 mice, and the systemic cell proliferative responses, which can be divided distinctively into fast and slow proliferations, were assessed by CFSE dye dilution. We found that the fast homeostatic proliferation of TEM cells was strictly regulated by both antigen and OX40 costimulatory signals and that the slow proliferation was dependent on IL-7. The simultaneous blockade of both OX40 and IL-7 signaling completely inhibited the both fast and slow proliferation. The antigen- and OX40-dependent fast proliferation preferentially expanded IL-17-producing helper T cells (Th17 cells). Thus, OX40 and IL-7 play synergistic, but distinct roles in the homeostatic proliferation of CD4(+) TEM cells.

Hepatocyte growth factor regulated tyrosine kinase substrate in the peripheral development and function of B-cells.

Hepatocyte growth factor (HGF)-regulated tyrosine kinase substrate (Hrs) is a vesicular sorting protein that functions as one of the endosomal-sorting proteins required for transport (ESCRT). Hrs, which binds to ubiquitinated proteins through its ubiquitin-interacting motif (UIM), contributes to the lysosomal transport and degradation of ubiquitinated membrane proteins. However, little is known about the relationship between B-cell functions and ESCRT proteins in vivo. Here we examined the immunological roles of Hrs in B-cell development and functions using B-cell-specific Hrs-deficient (Hrs(flox/flox);mb1(cre/)(+):Hrs-cKO) mice, which were generated using a cre-LoxP recombination system. Hrs deficiency in B-cells significantly reduced T-cell-dependent antibody production in vivo and impaired the proliferation of B-cells treated in vitro with an anti-IgM monoclonal antibody but not with LPS. Although early development of B-cells in the bone marrow was normal in Hrs-cKO mice, there was a significant decrease in the number of the peripheral transitional B-cells and marginal zone B-cells in the spleen of Hrs-cKO mice. These results indicate that Hrs plays important roles during peripheral development and physiological functions of B lymphocytes.

Gene therapy model of X-linked severe combined immunodeficiency using a modified foamy virus vector.

X-linked severe combined immunodeficiency (SCID-X1) is an inherited genetic immunodeficiency associated with mutations in the common cytokine receptor γ chain (γc) gene, and characterized by a complete defect of T and natural killer (NK) cells. Gene therapy for SCID-X1 using conventional retroviral (RV) vectors carrying the γc gene results in the successful reconstitution of T cell immunity. However, the high incidence of vector-mediated T cell leukemia, caused by vector insertion near or within cancer-related genes has been a serious problem. In this study, we established a gene therapy model of mouse SCID-X1 using a modified foamy virus (FV) vector expressing human γc. Analysis of vector integration in a human T cell line demonstrated that the FV vector integration sites were significantly less likely to be located within or near transcriptional start sites than RV vector integration sites. To evaluate the therapeutic efficacy, bone marrow cells from γc-knockout (γc-KO) mice were infected with the FV vector and transplanted into γc-KO mice. Transplantation of the FV-treated cells resulted in the successful reconstitution of functionally active T and B cells. These data suggest that FV vectors can be effective and may be safer than conventional RV vectors for gene therapy for SCID-X1.

Characterization of deamidation at Asn138 in L-chain of recombinant humanized Fab expressed from Pichia pastoris.

A method was previously established for evaluating Asn deamidation by matrix-assisted laser desorption/ionization time of flight-mass spectrometry using endoproteinase Asp-N. In this study, we demonstrated that this method could be applied to the identification of the deamidation site of the humanized fragment antigen-binding (Fab). First, a system for expressing humanized Fab from methylotrophic yeast Pichia pastoris was constructed, resulting in the preparation of ∼30 mg of the purified humanized Fab from 1 l culture. Analysis of the L-chain derived from recombinant humanized Fab that was heated at pH 7 and 100°C for 1 h showed the deamidation at Asn138 in the constant region. Then, we prepared L-N138D Fab and L-N138A Fab and examined their properties. The circular dichroism (CD) spectrum of the L-N138D Fab was partially different from that of the wild-type Fab. The measurement of the thermostability showed that L-N138D caused a significant decrease in the thermostability of Fab. On the other hand, the CD spectrum and thermostability of L-N138A Fab showed the same behaviour as the wild-type Fab. Thus, it was suggested that the introduction of a negative charge at position 138 in the L-chain by the deamidation significantly affected the stability of humanized Fab.

Y chromosome-linked B and NK cell deficiency in mice.

There are no primary immunodeficiency diseases linked to the Y chromosome, because the Y chromosome does not contain any vital genes. We have established a novel mouse strain in which all males lack B and NK cells and have Peyer's patch defects. By 10 wk of age, 100% of the males had evident immunodeficiencies. Mating these immunodeficient males with wild-type females on two different genetic backgrounds for several generations demonstrated that the immunodeficiency is linked to the Y chromosome and is inherited in a Mendelian fashion. Although multicolor fluorescence in situ hybridization analysis showed that the Y chromosome in the mutant male mice was one third shorter than that in wild-type males, exome sequencing did not identify any significant gene mutations. The precise molecular mechanisms are still unknown. Bone marrow chimeric analyses demonstrated that an intrinsic abnormality in bone marrow hematopoietic cells causes the B and NK cell defects. Interestingly, fetal liver cells transplanted from the mutant male mice reconstituted B and NK cells in lymphocyte-deficient Il2rg(-/-) recipient mice, whereas adult bone marrow transplants did not. Transducing the EBF gene, a master transcription factor for B cell development, into mutant hematopoietic progenitor cells rescued B cell but not NK cell development both in vitro and in vivo. These Y chromosome-linked immunodeficient mice, which have preferential B and NK cell defects, may be a useful model of lymphocyte development.

Homeostatic proliferation of naive CD4+ T cells in mesenteric lymph nodes generates gut-tropic Th17 cells.

Homeostatic proliferation of naive T cells in the spleen and cutaneous lymph nodes supplies memory-phenotype T cells. The "systemic" proliferative responses divide distinctly into fast or slow cell division rates. The fast proliferation is critical for generation of effector memory T cells. Because effector memory T cells are abundant in the lamina propria of the intestinal tissue, "gut-specific" homeostatic proliferation of naive T cells may be important for generation of intestinal effector memory T cells. However, such organ-specific homeostatic proliferation of naive T cells has not yet been addressed. In this study, we examined the gut-specific homeostatic proliferation by transferring CFSE-labeled naive CD4(+) T cells into sublethally irradiated mice and separately evaluating donor cell division and differentiation in the intestine, mesenteric lymph nodes (MLNs), and other lymphoid organs. We found that the fast-proliferating cell population in the intestine and MLNs had a gut-tropic α4ß7(+) Th17 phenotype and that their production was dependent on the presence of commensal bacteria and OX40 costimulation. Mesenteric lymphadenectomy significantly reduced the Th17 cell population in the host intestine. Furthermore, FTY720 treatment induced the accumulation of α4ß7(+)IL-17A(+) fast-dividing cells in MLNs and eliminated donor cells in the intestine, suggesting that MLNs rather than intestinal tissues are essential for generating intestinal Th17 cells. These results reveal that MLNs play a central role in inducing gut-tropic Th17 cells and in maintaining CD4(+) T cell homeostasis in the small intestine.

Ecological effects of crude oil residues on the functional diversity of soil microorganisms in three weed rhizospheres.

Ecological effects of crude oil residues on weed rhizospheres are still vague. The quantitative and diversity changes and metabolic responses of soil-bacterial communities in common dandelion (Taraxacum officinale), jerusalem artichoke (Silphium perfoliatum L.) and evening primrose (Acalypha australis L.) rhizospheric soils were thus examined using the method of carbon source utilization. The results indicated that there were various toxic effects of crude oil residues on the growth and reproduction of soil bacteria, but the weed rhizospheres could mitigate the toxic effects. Total heterotrophic counting colony-forming units (CFUs) in the rhizospheric soils were significantly higher than those in the non-rhizospheric soils. The culturable soil-bacterial CFUs in the jerusalem artichoke (S. perfoliatum) rhizosphere polluted with 0.50 kg/pot of crude oil residues were almost twice as much as those with 0.25 kg/pot and without the addition of crude oil residues. The addition of crude oil residues increased the difference in substrate evenness, substrate richness, and substrate diversity between non-rhizospheric and rhizospheric soils of T. officinale and A. australis, but there was no significant (p>0.05) difference in the Shannon's diversity index between non-rhizospheric and rhizospheric soils of S. perfoliatum. The rhizospheric response of weed species to crude oil residues suggested that S. perfoliatum may be a potential weed species for the effective plant-microorganism bioremediation of contaminated soils by crude oil residues.