The uterine secretome initiates growth of gynecologic tissues in ectopic locations.

Endosalpingiosis (ES) and endometriosis (EM) refer to the growth of tubal and endometrial epithelium respectively, outside of their site of origin. We hypothesize that uterine secretome factors drive ectopic growth. To test this, we developed a mouse model of ES and EM using tdTomato (tdT) transgenic fluorescent mice as donors. To block implantation factors, progesterone knockout (PKO) tdT mice were created. Fluorescent lesions were present after oviduct implantation with and without WT endometrium. Implantation was increased (p<0.05) when tdt oviductal tissue was implanted with endometrium compared to oviductal tissue alone. Implantation was reduced (p<0.0005) in animals implanted with minced tdT oviductal tissue with PKO tdT endometrium compared to WT endometrium. Finally, oviductal tissues was incubated with and without a known implantation factor, leukemia inhibitory factor (LIF) prior to and during implantation. LIF promoted lesion implantation. In conclusion, endometrial derived implantation factors, such as LIF, are necessary to initiate ectopic tissue growth. We have developed an animal model of ectopic growth of gynecologic tissues in a WT mouse which will potentially allow for development of new prevention and treatment modalities.

Identification and genetic validation of leukemia inhibitory factor super-enhancers in acute respiratory distress syndrome and lung cancer.

Super-enhancers play prominent roles in driving robust pathological gene expression, but they are hidden in human genome at noncoding regions, making them difficult to explore. Leukemia inhibitory factor (LIF) is a multifunctional cytokine crucially involved in acute respiratory distress syndrome (ARDS) and lung cancer progression. However, the mechanisms governing LIF regulation in disease contexts remain largely unexplored. In this study, we observed elevated levels of LIF in the bronchoalveolar lavage fluid (BALF) of patients with sepsis-related ARDS compared to those with nonsepsis-related ARDS. Furthermore, both basal and LPS-induced LIF expression were under the control of super-enhancers. Through analysis of H3K27Ac ChIP-seq data, we pinpointed three potential super-enhancers (LIF-SE1, LIF-SE2, and LIF-SE3) located proximal to the LIF gene in cells. Notably, genetic deletion of any of these three super-enhancers using CRISPR-Cas9 technology led to a significant reduction in LIF expression. Moreover, in cells lacking these super-enhancers, both cell growth and invasion capabilities were substantially impaired. Our findings highlight the critical role of three specific super-enhancers in regulating LIF expression and offer new insights into the transcriptional regulation of LIF in ARDS and lung cancer.

Generation of human cerebral organoids with a structured outer subventricular zone.

Outer radial glia (oRG) emerge as cortical progenitor cells that support the development of an enlarged outer subventricular zone (oSVZ) and the expansion of the neocortex. The in vitro generation of oRG is essential to investigate the underlying mechanisms of human neocortical development and expansion. By activating the STAT3 signaling pathway using leukemia inhibitory factor (LIF), which is not expressed in guided cortical organoids, we define a cortical organoid differentiation method from human pluripotent stem cells (hPSCs) that recapitulates the expansion of a progenitor pool into the oSVZ. The oSVZ comprises progenitor cells expressing specific oRG markers such as GFAP, LIFR, and HOPX, closely matching human fetal oRG. Finally, incorporating neural crest-derived LIF-producing cortical pericytes into cortical organoids recapitulates the effects of LIF treatment. These data indicate that increasing the cellular complexity of the organoid microenvironment promotes the emergence of oRG and supports a platform to study oRG in hPSC-derived brain organoids routinely.

Sortilin in Biliary Epithelial Cells Promotes Ductular Reaction and Fibrosis during Cholestatic Injury.

Cholestatic injuries are accompanied by ductular reaction, initiated by proliferation and activation of biliary epithelial cells (BECs), leading to fibrosis. Sortilin (encoded by Sort1) facilitates IL-6 secretion and leukemia inhibitory factor (LIF) signaling. This study investigated the interplay between sortilin and IL-6 and LIF in cholestatic injury-induced ductular reaction, morphogenesis of new ducts, and fibrosis. Cholestatic injury was induced by bile duct ligation (BDL) in wild-type and Sort1-/- mice, with or without augmentation of IL-6 or LIF. Mice with BEC sortilin deficiency (hGFAPcre.Sort1fl/fl) and control mice were subjected to BDL and 3,5-diethoxycarbonyl-1,4-dihydrocollidine diet (DDC) induced cholestatic injury. Sort1-/- mice displayed reduced BEC proliferation and expression of BEC-reactive markers. Administration of LIF or IL-6 restored BEC proliferation in Sort1-/- mice, without affecting BEC-reactive or inflammatory markers. Sort1-/- mice also displayed impaired morphogenesis, which was corrected by LIF treatment. Similarly, hGFAPcre.Sort1fl/fl mice exhibited reduced BEC proliferation, but similar reactive and inflammatory marker expression. Serum IL-6 and LIF were comparable, yet liver pSTAT3 was reduced, indicating that sortilin is essential for co-activation of LIF receptor/gp130 signaling in BECs, but not for IL-6 secretion. hGFAPcre.Sortfl/fl mice displayed impaired morphogenesis and diminished fibrosis after BDL and DDC. In conclusion, sortilin-mediated engagement of LIF signaling in BECs promoted ductular reaction and morphogenesis during cholestatic injury. This study indicates that BEC sortilin is pivotal for the development of fibrosis.

Impact of media supplements FGF2, LIF and IGF1 on the genome activity of porcine embryos produced in vitro.

In this article, we focused on the impact of precisely chemically modified FLI maturation medium enriched with fibroblast growth factor 2 (FGF2), leukemia inhibitory factor (LIF), insulin-like growth factor 1 (IGF1), and polyvinyl alcohol (PVA) and its potential to improve the efficiency of in vitro production of porcine embryos. We hypothesized that enhancing the composition of the maturation medium could result in an elevated production of embryos in vitro and can affect EGA. FLI medium resulted in a significantly higher rate of oocyte blastocyst maturation and formation compared to the control DMEM medium. In addition, immunocytochemical labelling confirmed the detection of UBF in 4-cell FLI parthenogenic embryos, suggesting similarities with natural embryo development. Through RNAseq analysis, upregulated genes present in 4-cell FLI embryos were found to play key roles in important biological processes such as cell proliferation, cell differentiation, and transcriptional regulation. Based on our findings, we demonstrated the positive influence of FLI medium in the evaluation of in vitro embryo production, EGA detection, transcriptomic and proteomic profile, which was confirmed by the positive activation of the embryonal genome in the 4-cell stage of parthenogenetically activated embryos.

Multiple cancer cell types release LIF and Gal3 to hijack neural signals.

Neural signals can significantly influence cancer prognosis. However, how cancer cells may proactively modulate the nervous system to benefit their own survival is incompletely understood. In this study, we report an overlapping pattern of brain responses, including that in the paraventricular nucleus of the hypothalamus, in multiple mouse models of peripheral cancers. A multi-omic screening then identifies leukemia inhibitory factor (LIF) and galectin-3 (Gal3) as the key cytokines released by these cancer cell types to trigger brain activation. Importantly, increased plasma levels of these two cytokines are observed in patients with different cancers. We further demonstrate that pharmacologic or genetic blockage of cancer cell-derived LIF or Gal3 signaling abolishes the brain responses and strongly inhibits tumor growth. In addition, ablation of peripheral sympathetic actions can similarly restore antitumor immunity. These results have elucidated a novel, shared mechanism of multiple cancer cell types hijacking the nervous system to promote tumor progression.

TGF-ß-driven LIF expression influences neutrophil extracellular traps (NETs) and contributes to peritoneal metastasis in gastric cancer.

Gastric cancer (GC), notorious for its poor prognosis, often advances to peritoneal dissemination, a crucial determinant of detrimental outcomes. This study intricately explores the role of the TGFß-Smad-LIF axis within the tumor microenvironment in propagating peritoneal metastasis, with a specific emphasis on its molecular mechanism in instigating Neutrophil Extracellular Traps (NETs) formation and encouraging GC cellular functions. Through a blend of bioinformatics analyses, utilizing TCGA and GEO databases, and meticulous in vivo and in vitro experiments, LIF was identified as pivotally associated with GC metastasis, notably, enhancing the NETs formation through neutrophil stimulation. Mechanistically, TGF-ß was substantiated to elevate LIF expression via the activation of the Smad2/3 complex, culminating in NETs formation and consequently, propelling peritoneal metastasis of GC. This revelation uncovers a novel potential therapeutic target, promising a new avenue in managing GC and mitigating its metastatic propensities.

Human Seminal Extracellular Vesicles Enhance Endometrial Receptivity Through Leukemia Inhibitory Factor.

Seminal extracellular vesicles (EVs) contain different subgroups that have diverse effects on sperm function. However, the effect of seminal EVs-especially their subgroups-on endometrial receptivity is largely unknown. Here, we found that seminal EVs could be divided into high-density EVs (EV-H), medium density EVs, and low-density EVs after purification using iodixanol. We demonstrated that EV-H could promote the expression and secretion of leukemia inhibitor factor (LIF) in human endometrial cells. In EV-H-treated endometrial cells, we identified 1274 differentially expressed genes (DEGs). DEGs were enriched in cell adhesion and AKT and STAT3 pathways. Therefore, we illustrated that EV-H enhanced the adhesion of human choriocarcinoma JAr cell spheroids to endometrial cells through the LIF-STAT3 pathway. Collectively, our findings indicated that seminal EV-H could regulate endometrial receptivity through the LIF pathway, which could provide novel insights into male fertility.

Bile acids serve as endogenous antagonists of the Leukemia inhibitory factor (LIF) receptor in oncogenesis.

The leukemia inhibitory factor (LIF) is member of interleukin (IL)-6 family of cytokines involved immune regulation, morphogenesis and oncogenesis. In cancer tissues, LIF binds a heterodimeric receptor (LIFR), formed by a LIFRß subunit and glycoprotein(gp)130, promoting epithelial mesenchymal transition and cell growth. Bile acids are cholesterol metabolites generated at the interface of host metabolism and the intestinal microbiota. Here we demonstrated that bile acids serve as endogenous antagonist to LIFR in oncogenesis. The tissue characterization of bile acids content in non-cancer and cancer biopsy pairs from gastric adenocarcinomas (GC) demonstrated that bile acids accumulate within cancer tissues, with glyco-deoxycholic acid (GDCA) functioning as negative regulator of LIFR expression. In patient-derived organoids (hPDOs) from GC patients, GDCA reverses LIF-induced stemness and proliferation. In summary, we have identified the secondary bile acids as the first endogenous antagonist to LIFR supporting a development of bile acid-based therapies in LIF-mediated oncogenesis.

Leukemia inhibitory factor suppresses hepatic de novo lipogenesis and induces cachexia in mice.

Cancer cachexia is a systemic metabolic syndrome characterized by involuntary weight loss, and muscle and adipose tissue wasting. Mechanisms underlying cachexia remain poorly understood. Leukemia inhibitory factor (LIF), a multi-functional cytokine, has been suggested as a cachexia-inducing factor. In a transgenic mouse model with conditional LIF expression, systemic elevation of LIF induces cachexia. LIF overexpression decreases de novo lipogenesis and disrupts lipid homeostasis in the liver. Liver-specific LIF receptor knockout attenuates LIF-induced cachexia, suggesting that LIF-induced functional changes in the liver contribute to cachexia. Mechanistically, LIF overexpression activates STAT3 to downregulate PPARα, a master regulator of lipid metabolism, leading to the downregulation of a group of PPARα target genes involved in lipogenesis and decreased lipogenesis in the liver. Activating PPARα by fenofibrate, a PPARα agonist, restores lipid homeostasis in the liver and inhibits LIF-induced cachexia. These results provide valuable insights into cachexia, which may help develop strategies to treat cancer cachexia.

Dysregulated expression of GATA2 and GATA6 transcription factors in adenomyosis: implications for impaired endometrial receptivity.

OBJECTIVE: To study the effect of adenomyosis on the localized expression of the GATA binding proteins 2 and 6 (GATA2 and GATA6) zinc-finger transcription factors that are involved in proliferation of hematopoietic and endocrine cell lineages, cell differentiation, and organogenesis, potentially leading to impaired endometrial implantation. DESIGN: Laboratory based experimental study. SETTING: Academic hospital and laboratory. PATIENTS: Human endometrial stromal cells (HESCs) of reproductive age patients, 18-45 years of age, with adenomyosis were compared with patients with no pathology and leiomyomatous uteri as controls (n = 4 in each group, respectively). Additionally, midsecretory phase endometrial sections were obtained from patients with adenomyosis and control patients with leiomyoma (n = 8 in each group, respectively). INTERVENTIONS: GATA2 and GATA6 immunohistochemistry and H-SCORE were performed on the midsecretory phase endometrial sections from adenomyosis and leiomyoma control patients (n = 8 each, respectively). Control and adenomyosis patient HESC cultures were treated with placebo or 10-8 M estradiol (E2), or decidualization media (EMC) containing 10-8 M E2, 10-7 M medroxyprogesterone acetate, and 5 × 10-5 M cAMP for 6 and 10 days. Additionally, control HESC cultures (n = 4) were transfected with scrambled small interfering RNA (siRNA) (control) or GATA2-specific siRNAs for 6 days while adenomyosis HESC cultures (n = 4) were transfected with human GATA2 expression vectors to silence or induce GATA2 overexpression. MAIN OUTCOME MEASURES: Immunohistochemistry was performed to obtain GATA2 and GATA6 H-SCORES in adenomyosis vs. control patient endometrial tissue. Expression of GATA2, GATA6, insulin-like growth factor-binding protein 1 (IGFBP1), prolactin (PRL), progesterone receptor (PGR), estrogen receptor 1 (ESR1), leukemia inhibitory factor (LIF), and Interleukin receptor 11 (IL11R) messenger RNA (mRNA) levels were analyzed using by qPCR with normalization to ACTB. Silencing and overexpression experiments also had the corresponding mRNA levels of the above factors analyzed. Western blot analysis was performed on isolated proteins from transfection experiments. RESULTS: Immunohistochemistry revealed an overall fourfold lower GATA2 and fourfold higher GATA6 H-SCORE level in the endometrial stromal cells of patients with adenomyosis vs. controls. Decidual induction with EMC resulted in significantly lower GATA2, PGR, PRL and IGFBP1 mRNA levels in HESC cultures from patients with adenomyosis patient vs. controls. Leukemia inhibitory factor and IL11R mRNA levels were also significantly dysregulated in adenomyosis HESCs compared with controls. . Silencing of GATA2 expression in control HESCs induced an adenomyosis-like state with significant reductions in GATA2, increases in GATA6 and accompanying aberrations in PGR, PRL, ESR1 and LIF levels. Conversely, GATA2 overexpression via vector in adenomyosis HESCs caused partial restoration of the defective decidual response with significant increases in GATA2, PGR, PRL and LIF expression. CONCLUSION: In-vivo and in-vitro experiment results demonstrate that there is an overall inverse relationship between endometrial GATA2 and GATA6 levels in patients with adenomyosis who have diminished GATA2 levels and concurrently elevated GATA6 levels. Additionally, lower GATA2 and higher GATA6 levels, together with aberrant levels of important receptors and implantation factors, such as ESR1, PGR, IGFBP1, PRL, LIF, and IL11R mRNA in HESCs from patients with adenomyosis or GATA2-silenced control HESCs, support impaired decidualization. These effects were partially restored with GATA2 overexpression in adenomyosis HESCs, demonstrating a potential therapeutic target.

LIF Aggravates Pulpitis by Promoting Inflammatory Response in Macrophages.

Leukemia inhibitory factor (LIF) has been recognized as a novel inflammatory modulator in inflammation-associated diseases. This study aimed to investigate the modulation of LIF in dental pulp inflammation. Experimental pulpitis was established in wild-type (WT) and Lif-deficient (Lif-/-) mice. Histological and immunostaining analyses were conducted to assess the role of LIF in the progression of pulpitis. Mouse macrophage cell line (RAW264.7) was treated with LPS to simulate an inflammatory environment. Exogenous LIF was added to this system to examine its modulation in macrophage inflammatory response in vitro. Primary bone marrow-derived macrophages (BMDMs) from WT and Lif-/- mice were isolated and stimulated with LPS to confirm the effect of Lif deletion on macrophage inflammatory response. Supernatants from LIF and LPS-treated human dental pulp cells (hDPCs) were collected and added to macrophages. Macrophage chemotaxis was assessed using transwell assays. The results showed an increased expression of LIF and LIFR with the progression of pulpitis, and LIFR was highly expressed in macrophages. Lif deficiency alleviated experimental pulpitis with the reduction of pro-inflammatory cytokines and macrophage infiltration. Exogenous LIF promoted inflammatory response of LPS-induced macrophages through a STAT3/p65-dependent pathway. Consistently, Lif deletion inhibited macrophage inflammatory response in vitro. Supernatants of LIF-treated hDPCs enhanced macrophage migration in LPS-induced inflammatory environment. Our findings demonstrated that LIF aggravates pulpitis by promoting macrophage inflammatory response through a STAT3/p65-dependent pathway. Furthermore, LIF plays a crucial role in driving the recruitment of macrophages to inflamed pulp tissue by promoting chemokine secretion in DPCs.

MDM2-p53 mediate a miR-181c-3p/LIF axis to regulate low dose-rate radiation-induced DNA damage in human B lymphocytes.

PURPOSE: Prolonged exposure to low dose-rate radiation (LDRR) is of growing concern to public health. Recent evidences indicates that LDRR causes deleterious health effects and is closely related to miRNAs. The aim of our study is to investigate the relationship between miRNAs and DNA damage caused by LDRR. MATERIALS AND METHODS: In this study, we irradiated C57BL/6J mice with 12.5µGy/h dose of γ ray emitted from uranium ore for 8 h a day for 120 days at a total dose of 12 mGy, and identified differentially expressed miRNAs from the mice long-term exposed to LDRR through isolating serum RNAs, constructing small RNA library, Illumina sequencing. To further investigate the role of differential miRNA under LDRR，we first built DNA damage model in Immortal B cells irradiated with 12.5µGy/h dose of γ ray for 28 days at a total dose of 9.4 mGy. Then, we chose the highly conserved miR-181c-3p among 12 miRNA and its mechanism in alleviating DNA damage induced by LDRR was studied by transfection, quantitative PCR, luciferase assay, and Western blot. RESULTS AND CONCLUSIONS: We have found that 12 differentially expressed miRNAs including miR-181c-3p in serum isolated from irradiated mice. Analysis of GO and KEGG indicated that target genes of theses 12 miRNA enriched in pathways related to membrane, protein binding and cancer. Long-term exposure to LDRR induced upregulation of gamma-H2A histone family member X (γ-H2AX) expression, a classical biomarker for DNA damage in B cells. miR-181c-3p inhibited Leukemia inhibitory factor (LIF) expression via combining its 3'UTR. LIF, MDM2, p53, and p-p53-s6 were upregulated after exposure to LDRR. In irradiated B cells, Transfection of miR-181c-3p reduced γ-H2AX expression and suppressed LIF and MDM2 protein levels, whereas p-p53-s6 expression was increased. As expected, the effect of LIF inhibition on irradiated B cells was similar to miR-181c-3p overexpression. Our results suggest that LDRR alters miRNA expression and induces DNA damage. Furthermore, miR-181c-3p can alleviate LDRR-induced DNA damage via the LIF/MDM2/p-p53-s6 pathway in human B lymphocytes. This could provide the basis for prevention and treatment of LDRR injury.

Leukemia inhibitory factor shortens primary cilia by upregulating C-C motif chemokine 2 in human neural stem/progenitor cells.

Primary cilia on neural stem/progenitor cells (NSPCs) play an important role in determining cell fate, although the regulatory mechanisms involved in the ciliogenesis remain largely unknown. In this study, we analyzed the effect of the leukemia inhibitory factor (LIF) for the primary cilia in immortalized human NSPCs. LIF withdrawal elongated the primary cilia length, whereas the addition of LIF shortened it. Microarray gene expression analysis revealed that differentially expressed genes (DEGs) associated with LIF treatment were related with the multiple cytokine signaling pathways. Among the DEGs, C-C motif chemokine 2 (CCL2) had the highest ranking and its increase in the protein concentration in the NSPCs-conditioned medium after the LIF treatment was confirmed by ELISA. Interestingly, we found that CCL2 was a negative regulator of cilium length, and LIF-induced shortening of primary cilia was antagonized by CCL2-specific antibody, suggesting that LIF could influence cilia length via upregulating CCL2. The shortening effect of LIF and CCL2 on primary cilia was also observed in SH-SY5Y cells. The results of the study suggested that the LIF-CCL2 axis may well be a regulator of NSPCs and its primary cilia length, which could affect multiple cellular processes, including NSPC proliferation and differentiation.

AUF1-induced circular RNA hsa_circ_0010467 promotes platinum resistance of ovarian cancer through miR-637/LIF/STAT3 axis.

BACKGROUND: Increasing evidences has indicated that primary and acquired resistance of ovarian cancer (OC) to platinum is mediated by multiple molecular and cellular factors. Understanding these mechanisms could promote the therapeutic efficiency for patients with OC. METHODS: Here, we screened the expression pattern of circRNAs in samples derived from platinum-resistant and platinum-sensitive OC patients using RNA-sequencing (RNA-seq). The expression of hsa_circ_0010467 was validated by Sanger sequencing, RT-qPCR, and fluorescence in situ hybridization (FISH) assays. Overexpression and knockdown experiments were performed to explore the function of hsa_circ_0010467. The effects of hsa_circ_0010467 on enhancing platinum treatment were validated in OC cells, mouse model and patient-derived organoid (PDO). RNA pull-down, RNA immunoprecipitation (RIP), and dual-luciferase reporter assays were performed to investigate the interaction between hsa_circ_0010467 and proteins. RESULTS: Increased expression of hsa_circ_0010467 is observed in platinum-resistant OC cells, tissues and serum exosomes, which is positively correlated with advanced tumor stage and poor prognosis of OC patients. Hsa_circ_0010467 is found to maintain the platinum resistance via inducing tumor cell stemness, and silencing hsa_circ_0010467 substantially increases the efficacy of platinum treatment on inhibiting OC cell proliferation. Further investigation reveals that hsa_circ_0010467 acts as a miR-637 sponge to mediate the repressive effect of miR-637 on leukemia inhibitory factor (LIF) and activates the LIF/STAT3 signaling pathway. We further discover that AUF1 could promote the biogenesis of hsa_circ_0010467 in OC. CONCLUSION: Our study uncovers the mechanism that hsa_circ_0010467 mediates the platinum resistance of OC through AUF1/hsa_circ_0010467/miR-637/LIF/STAT3 axis, and provides potential targets for the treatment of platinum-resistant OC patients.

The astrocytic TRPA1 channel mediates an intrinsic protective response to vascular cognitive impairment via LIF production.

Vascular cognitive impairment (VCI) refers to cognitive alterations caused by vascular disease, which is associated with various types of dementia. Because chronic cerebral hypoperfusion (CCH) induces VCI, we used bilateral common carotid artery stenosis (BCAS) mice as a CCH-induced VCI model. Transient receptor potential ankyrin 1 (TRPA1), the most redox-sensitive TRP channel, is functionally expressed in the brain. Here, we investigated the pathophysiological role of TRPA1 in CCH-induced VCI. During early-stage CCH, cognitive impairment and white matter injury were induced by BCAS in TRPA1-knockout but not wild-type mice. TRPA1 stimulation with cinnamaldehyde ameliorated BCAS-induced outcomes. RNA sequencing analysis revealed that BCAS increased leukemia inhibitory factor (LIF) in astrocytes. Moreover, hydrogen peroxide-treated TRPA1-stimulated primary astrocyte cultures expressed LIF, and culture medium derived from these cells promoted oligodendrocyte precursor cell myelination. Overall, TRPA1 in astrocytes prevents CCH-induced VCI through LIF production. Therefore, TRPA1 stimulation may be a promising therapeutic approach for VCI.

Deletion of p66Shc Dysregulates ERK and STAT3 Activity in Mouse Embryonic Stem Cells, Enhancing Their Naive-Like Self-Renewal in the Presence of Leukemia Inhibitory Factor.

The ShcA adapter protein is necessary for early embryonic development. The role of ShcA in development is primarily attributed to its 52 and 46 kDa isoforms that transduce receptor tyrosine kinase signaling through the extracellular signal regulated kinase (ERK). During embryogenesis, ERK acts as the primary signaling effector, driving fate acquisition and germ layer specification. P66Shc, the largest of the ShcA isoforms, has been observed to antagonize ERK in several contexts; however, its role during embryonic development remains poorly understood. We hypothesized that p66Shc could act as a negative regulator of ERK activity during embryonic development, antagonizing early lineage commitment. To explore the role of p66Shc in stem cell self-renewal and differentiation, we created a p66Shc knockout murine embryonic stem cell (mESC) line. Deletion of p66Shc enhanced basal ERK activity, but surprisingly, instead of inducing mESC differentiation, loss of p66Shc enhanced the expression of core and naive pluripotency markers. Using pharmacologic inhibitors to interrogate potential signaling mechanisms, we discovered that p66Shc deletion permits the self-renewal of naive mESCs in the absence of conventional growth factors, by increasing their responsiveness to leukemia inhibitory factor (LIF). We discovered that loss of p66Shc enhanced not only increased ERK phosphorylation but also increased phosphorylation of Signal transducer and activator of transcription in mESCs, which may be acting to stabilize their naive-like identity, desensitizing them to ERK-mediated differentiation cues. These findings identify p66Shc as a regulator of both LIF-mediated ESC pluripotency and of signaling cascades that initiate postimplantation embryonic development and ESC commitment.

Tumor-derived interleukin-1α and leukemia inhibitory factor promote extramedullary hematopoiesis.

Extramedullary hematopoiesis (EMH) expands hematopoietic capacity outside of the bone marrow in response to inflammatory conditions, including infections and cancer. Because of its inducible nature, EMH offers a unique opportunity to study the interaction between hematopoietic stem and progenitor cells (HSPCs) and their niche. In cancer patients, the spleen frequently serves as an EMH organ and provides myeloid cells that may worsen pathology. Here, we examined the relationship between HSPCs and their splenic niche in EMH in a mouse breast cancer model. We identify tumor produced IL-1α and leukemia inhibitory factor (LIF) acting on splenic HSPCs and splenic niche cells, respectively. IL-1α induced TNFα expression in splenic HSPCs, which then activated splenic niche activity, while LIF induced proliferation of splenic niche cells. IL-1α and LIF display cooperative effects in activating EMH and are both up-regulated in some human cancers. Together, these data expand avenues for developing niche-directed therapies and further exploring EMH accompanying inflammatory pathologies like cancer.

Dismantling the tumoral cloak of self-protection.

Tumors protect themselves from immune clearance by promoting extramedullary hematopoiesis. A new study in PLOS Biology provides insights into the mechanisms underlying this process, which may hold the key to disrupting generation of the immunosuppressive tumor microenvironment.

Immunohistochemistry of Leukemia Inhibitory Factor and Integrin αVß3 in Mouse Endometrium Following Kisspeptin-54 Ovulation Trigger.

Kisspeptin (KP) is a group of hypothalamic neuropeptides encoded by KISS-1 gene. KP-54, a 54-amino-acid peptide, helps regulate the hypothalamic-pituitary-ovarian axis and plays a potential role in implantation. C57BL/6 J female mice were superovulated via intraperitoneal injection of 5 International Units (IU) pregnant mare serum gonadotrophin (day 1). Forty-eight hours later, mice (5/group) were injected with phosphate-buffered saline (PBS) (group A), 5 IU human chorionic gonadotrophin (hCG) (group B), or 3 nmol KP-54 (group C). On day 7, mice were euthanized and uteri excised to create paraformaldehyde-fixed paraffin-embedded sections that were immunostained for the implantation markers: leukemia inhibitory factor (LIF) and integrin αVß3 (ITG αVß3). Slides were scored for intensity of staining in endometrial glandular epithelium (GE) and stromal cells (SCs) via histoscore (H-score). Data were analyzed using the Kruskal-Wallis test followed by the Mann-Whitney U test for pairwise comparisons. LIF expression was significantly higher in GE and SCs of mice triggered with KP-54 compared to placebo (P = .009 for both), but only higher than hCG trigger group in SCs (P = .009). Meanwhile, ITG αVß3 expression was significantly higher in SCs of mice triggered with KP-54 compared to placebo (P = .028). In conclusion, using KP-54 as an ovulation trigger resulted in higher expression of the implantation markers LIF and ITG αVß3 in mice endometrium compared to hCG or placebo. This suggests a potential role for KP-54 trigger in improving embryo implantation in clinical IVF. However, further studies are needed to correlate these results with clinical implantation rates and pregnancy outcomes.