Expression Of Lineage Markers Research Articles

GPR160 regulates the self-renewal and pluripotency of mouse embryonic stem cells via JAK1/STAT3 signal pathway

G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors and regulate various physiological and pathological processes. Despite extensive studies, the roles of GPCRs in mouse embryonic stem cells (mESCs) represent a significant data gap. Here, we show that GPR160, a class A member of GPCRs, is dramatically downregulated concurrent with mESC differentiation into embryoid bodies in vitro. Knockdown of GPR160 leads to downregulation of the expression of pluripotency-associated transcription factors and upregulation of the expression of lineage markers, accompanying with the arrest of the mESC cell cycle in the G0/G1 phase. RNA-seq analysis shows that GPR160 participates in the JAK/STAT signaling pathway crucial for maintaining ESC stemness, and the knockdown of GPR160 results in the downregulation of STAT3 phosphorylation level, which in turn is partially rescued by colivelin, a STAT3 activator. Constant with these observations, GPR160 physically interacts with JAK1, and cooperates with leukemia inhibitory factor receptor (LIFR) and gp130 to activate the STAT3 pathway. In summary, our results suggest that GPR160 regulates mESC self-renewal and pluripotency by interacting with the JAK1-LIFR-gp130 complex to mediate the JAK1/STAT3 signaling pathway.

Abstract 1053: The Influence of PD1 and TIM3 Expression on CD4+CD103+ and CD8+CD103+ Cells in Glioblastoma Progression

Abstract Glioblastoma (GB), IDH-wildtype, is the most common and aggressive high-grade primary malignant brain tumor with extremely poor outcome. Although the use of immune checkpoint inhibitors (ICIs) in GB has shown disappointing results, the identification of a small subgroup of responders underpins the role of the intratumoral immune contexture, in particular tumour-infiltrating lymphocytes (TILs), in determining disease outcome. This study aims to define the features of TIL subpopulations correlating with GB prognosis, and to establish in parallel the predictive roles of peripheral T cell subsets. A single cohort observational study, including patients undergoing GB resection and standard therapeutic and follow-up approaches in Neuro-Oncology, was conducted. Of the 45 patients, histologically confirmed WHO grade 4, 26 had MGMT promoter methylation (60.0%), 24 were male (53.3%) and the median age of young patients (≤63 years) vs elderly patients (>63 years) was 57 vs 71, respectively. Predictors of OS were KPS (≥70 vs <70: 14.7 vs 7.5 months, p=0.0007) and GTR (GTR vs non-GRT: 15 vs 9 months, p=0.004) whereas patients with methylated MGMT promoter had non-significant longer median OS compared to those with unmethylated promoter (14.5 vs 10.5 months). Patients were characterized for the expression of lineage, differentiation, memory, activation, and inhibition markers on intratumoral and peripheral CD4+ and CD8+ T cell subpopulations, and the correlation of an array of CD4+ and CD8+ T cell subsets with OS or PFS was evaluated by multiparametric flow cytometry and uni/multivariate analyses. Intratumoral immune infiltrate was positively associated with CD8+CD103+ tissue-resident memory T cells (Trm), and in particular with CD8+CD103+ Trm expressing PD1 and TIM3 rather than CD4+ Trm. Low CD8+CD103+PD1+ Trm resulted significantly associated with better OS and PFS (p=0.02 and 0.0031, respectively) and even higher significant was the correlation with better OS and PFS of low CD8+CD103+TIM3+ Trm (p=0.0002 and 0.0033, respectively) and CD8+CD103+PD1+TIM3+ Trm (p<0.0001, both). On multivariate analysis, low CD8+CD103+PD1+TIM3+ Trm and KPS ≥70 were confirmed to be the most predictive independent factors associated with longer OS (hazard ratios - HR [95%CI]: 0.14 [0.04 - 0.52] p˂0.001, 0.39 [0.16 - 0.96] p=0.04, respectively). Moreover, CD8+CD103+ Trm subpopulations resulted age-related predictors for GB survival. Consistent with this finding, in vitro PD1 and TIM3 blockade released the capability of intratumoral T cells to produce the effector cytokines IFN-γ and TNF-α, and the cytotoxic factor GrzB. Conversely, T cells expressing PD1 and TIM3 of peripheral blood did not show any prognostic significance. In conclusion, low frequency of Trm expressing PD1 or TIM3 or both markers defined TIL subsets as independent positive prognostic factors for patient survival. Citation Format: Lucia Gabriele, Giulia Romagnoli, Quintino Giorgio D'Alessandris, Imerio Capone, Andrea Tavilla, Irene Canini, Caterina Lapenta, Mariachiara Buccarelli, Martina Giordano, Valentina Tirelli, Massimo Sanchez, Alessandra Fragale, Stefano Giannetti, Rina Di Bonaventura, Liverana Lauretti, Mauro Biffoni, Lucia Ricci-Vitiani, Roberto Pallini. The Influence of PD1 and TIM3 Expression on CD4+CD103+ and CD8+CD103+ Cells in Glioblastoma Progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1053.

Abstract 2756: Single cell analysis reveals treatment response-associated plastic cell state and lineage switching in aggressive variant prostate cancer

Abstract Prostate cancer (PCa) is a common malignancy in men over 65, ranking as the second leading cause of cancer-related deaths among men in the United States. While most prostate cancers respond to androgen receptor (AR) targeting therapies, Aggressive Variant Prostate Cancers (AVPCs), characterized by RB1, Tp53, and/or PTEN alterations, do not. AVPCs exhibit lineage plasticity in preclinical models, enabling the expression of non-prostate epithelial lineage markers to adapt to therapeutic pressures. However, a measurable definition of lineage plasticity as a potential therapeutic target for clinical trials is currently lacking. To arrive at said definition, we perform single-nuclei RNA sequencing (snRNA-seq) on lymph node metastases from twelve AVPC patients with matched sample pairs of both pre- and post-treatment. Additionally, we include snRNA-seq data from eight non-AVPC patients as a baseline. Expanding upon our prior establishment of tumor-specific total mRNA expression (TmS) as an indicator of tumor cell lineage plasticity (Nature Biotechnology, PMID: 35697807), we employ unique molecular identifier (UMI) counts from individual cells to quantify this plasticity. We reveal a distinct cluster of tumor cells with notably high UMI counts in resistant samples, indicative of a less differentiated state and increased transcriptional diversity. This high-UMI cluster is marked by significant enrichment in pathways associated with epithelial-mesenchymal transition (EMT), stemness, one-carbon metabolism, and arginine metabolism pathways. Concurrently, there is a reduction in activity within the androgen receptor (AR) and DNA damage repair pathways. These characteristics suggest an enhanced capacity for lineage switching in AVPC tumor cells, potentially contributing to evasion from targeted therapies. Moreover, immune components within resistant samples consistently display lower UMI counts, indicating a diminished propensity for lineage plasticity. In conclusion, we present a better understanding of lineage switching in therapeutic resistance in AVPCs, paving the way for novel treatment strategies in PCa management. Citation Format: Shuai Guo, Elavarasan Subramani, Daniel E. Frigo, Patrick G. Pilié, Sangeeta Goswami, Rama Soundararajan, Ana Aparicio, Wenyi Wang. Single cell analysis reveals treatment response-associated plastic cell state and lineage switching in aggressive variant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2756.

The ELN 2022 Risk Stratification Has No Impact on the Dismal Prognosis of Patients with Acute Undifferentiated Leukemia

Introduction: Acute undifferentiated leukemia (AUL) is a rare subtype of acute leukemia. It is characterized by lack of expression of myeloid or lymphoid lineage markers, frequently expressing CD56 or CD7. The dismal prognosis of AUL was reported in small studies; the largest previously reported group with this disorder included 24 patients (Weinberg, Mod Pathol, 2019). Furthermore, data are lacking regarding cytogenetic and molecular patterns of AUL. In this study, the cytogenetic and molecular changes of AUL patients are described, together with the clinical outcome. Methods: AUL was defined, in accordance with the WHO classification, as an acute leukemia that does not qualify for myeloid, B- or T-cell lineage. Immunophenotyping of BM cells at diagnosis was performed using 8-color flow cytometry. Multi-parameter Cytognos acute orientation tube (ALOT) and the combination of the following antigens were used: CD34/CD117/CD14/CD56/CD36/CD123/HLA-DR/CD45/CD64/CD11c. (Weinberg, Mod Pathol, 2019). Results: Three hundred and eighty-five patients with acute myeloid leukemia (AML) were diagnosed at Rambam Health Care Campus in Haifa, Israel between April 2015 and April 2021, of whom 30 (8%) were defined as AUL. The baseline characteristics are presented in Table 1. The median age was 62 years, none of the patients harbored NPM1 mutation, with 1 patient expressing FLT3-ITD mutation. Cytogenetic analysis was completed for all patients: 9 (30%) had adverse-risk cytogenetics by ELN 2022 criteria. A comprehensive molecular study using molecular inverted probe was performed on all patients, with final results available on 17. Nine of these 17 (53%) had high-risk mutations; RUNX1 was found in 4 patients. Notably, 4 other patients had JAK2 mutation, with or without previous myeloproliferative neoplasm. Only 3 patients had mutations characterizing secondary AML (Lindsley, Blood, 2015). Only 2 patients in this cohort had TP53 mutation or del17p. Fourteen patients were classified as adverse-risk AML by ELN 2022 using cytogenetic and molecular markers, while 15 were classified as intermediate risk. Only 4 patients in this adverse-risk cohort were not allogeneic hematopoietic stem cell transplant (HSCT) candidates due to age or comorbidity limitations. The outcome of the cohort is presented in Table 2. Twenty-two fit patients received 7+3 intensive chemotherapy, of whom 10 achieved complete remission (CR) after induction. Four of the 10 patients needed reinduction chemotherapy due to a high blast count on the bone marrow performed at day 14. Five patients were treated with low-intensity therapies such as hypomethylating agents ± novel agents; 2 achieved CR. One patient received FLAG-Ida chemotherapy and another patient was treated with ECOG1910 protocol due to clinical presentation more compatible with acute lymphoid leukemia; both achieved CR. Of the 14 patients achieving CR, 4 relapsed before HSCT and needed further salvage therapy. Eventually, 13 (50% of the transplant-eligible candidate cohort) patients proceeded to HSCT. Relapse occurred in 14 patients (10 post-HSCT and 4 before HSCT), none of them achieved long-term survival. Four of the 30 patients are alive, all in remission. The median overall survival of the entire cohort is 1 year (Fig 1). The outcome of patients with adverse or intermediate risk according to the ELN risk classification did not differ. The CR rate and relapse rate and median overall survival (OS) were similar in both groups (Table 2; Fig 1). Discussion: These data emphasize the dismal outcome of patients diagnosed with AUL, with the 5-year OS of 7.5%, far lower than the survival of other types of acute leukemia. In this cohort, 15 patients were classified as intermediate risk AML; yet, their CR rate and long-term survival were not different from the whole cohort. The CR rate achieved with the widely used 7+3 protocol, was inferior, raising the question whether this protocol should be the “standard of choice” in such patients. A limitation of this study is that not all patients were evaluated by the NGS panel, bringing about the issue whether more patients had high-risk mutations, who would then be classified as adverse risk. Conclusion: The unique subtype of AUL is associated with a particularly adverse risk genotype, irrespective of known prognostic determinants, as in the 2022 ELN classification.

Single-Cell Transcriptomics Reveal Altered Hematopoietic Mechanisms Driven By T21 and GATA1s

Introduction Trisomy 21 (T21) is associated with baseline erythrocytosis and thrombocytopenia and risk of transient abnormal myelopoiesis (TAM) and acute megakaryoblastic leukemia of Down syndrome (ML-DS). TAM and ML-DS are characterized by mutations in the transcription factor GATA1, resulting in the truncated isoform GATA1s (G1S). We previously found that T21 increases erythropoiesis, while G1S severely impairs erythroid development but enhances megakaryocyte (MK) proliferation (Byrska-Bishop et al, JCI 2015). To better understand how T21 and G1S each impact hematopoiesis, we performed single-cell RNA sequencing (scRNA-seq) of multipotent and late hematopoietic progenitor cells (HPCs) differing only by chromosome 21 and/or G1S status. Methods Four isogenic human induced pluripotent stem cell (iPSC) lines differing only by chromosome 21 (euploid vs. T21) and/or GATA1 (WT vs. G1S) status underwent hematopoietic differentiation by embryoid body formation. Cells were collected at 3 timepoints: on day 7 (D7), CD41 +235 + multipotent HPCs were purified by flow cytometry and on days 9 (D9) and 11 (D11), late HPCs biased to a single lineage were collected. Cells were sequenced by scRNA-seq and underwent quality control followed by clustering and analysis using Seurat. Clusters were manually annotated based on expression of 141 key hematopoietic genes, including aggregated expression of lineage markers. Early vs. committed lineage clusters were determined based on the relative expression of lineage-specific markers. Within each lineage, differentially expressed genes (DEGs) associated with a genetic background were assessed using the Wilcoxon rank-sum test. The χ² test was used to compare categorical data. A 2-tailed p or adjusted p <0.05 was considered statistically significant. Results Cluster annotation revealed HPC, early and committed erythroid and MK, and myeloid cells (Figure 1). D7 T21/G1S HPCs surprisingly showed an erythroid bias, with upregulation of genes such as GYPA and AHSP, while euploid/G1S HPCs showed a MK bias, with upregulation of genes including PF4V1 and PF4. With wtGATA1, neither euploid nor T21 D7 HPCs showed a significant lineage skew. On D9 and D11, the euploid/WT, T21/WT, and T21/G1S cells developed subpopulations committing to the erythroid lineage, while the euploid/G1S cells demonstrated minimal erythroid potential (Figure 1). Across all 3 timepoints, early and committed erythrocytes from T21 and euploid cells with G1S had a greater number of combined DEGs than their wtGATA1 counterparts (G1S vs. WT, T21: 692 vs. 378; euploid: 1235 vs. 599). On D9, T21 was associated with a greater erythroid skew (38.6% of T21/WT and 32.2% of T21/G1S cells vs. 27.8% of euploid/WT cells; p <0.00001). By D11, this erythroid drive was no longer apparent, and the T21/G1S erythrocytes were significantly less mature (Table 1; p <0.00001). These data suggest that T21 initially enhances erythropoietic drive, while G1S results in a near-complete erythroid block in euploid cells but an incomplete developmental block with T21. All 4 genotypes yielded MK subpopulations on D9 and D11 (Figure 1). With wtGATA1, euploid and T21 MKs were predominantly early MKs by D11 (Table 1). Interestingly, G1S was associated with enhanced MK commitment and maturation in the euploid context but arrest at the early stage with T21 (Table 1; p <0.00001). G1S was again associated with increased DEGs compared to wtGATA1 (G1S vs. WT, T21: 594 vs. 454; euploid: 1689 vs. 1310). These data suggest that G1S in a euploid background promotes MK differentiation, but T21 and G1S cooperate to generate immature, abnormal MKs. Conclusions Although the hematopoietic abnormalities and leukemic risk of T21 have been well-described, the underlying developmental events remain unclear. This scRNA-seq timecourse of HPCs differentiated from isogenic iPSCs reveals the individual and synergistic effects of T21 and G1S. Overall, T21 enhances erythropoietic drive while G1S alone suppresses erythropoiesis. G1S in euploid cells enhances megakaryopoiesis, but with T21, megakaryopoietic commitment and maturation are uncoupled with a strong bias to early MKs. Together, the competing effects of T21 and G1S appear to result in abnormal, immature erythrocytes and MKs with impaired lineage commitment, consistent with a pro-leukemic phenotype.

The Impact of ZNF384 Rearranged on Antigen Editing during Treatment-Specific Selective Pressures in Adult B Cell Acute Lymphoid Leukemia

Objectives: Recent evidence shows that zinc finger protein 384 rearrangement (ZNF384r) was associated with the aberrant myeloid marker expression at diagnosis, which has been identified as a distinct subset of B cell acute lymphoid leukemia(B-ALL) related to an intermediate or even good prognosis during traditional therapy. However, there exists an indeterminate understanding of whether ZNF384r has a potential impact on antigen editing during treatment-specific selective pressures and shares the same prognostic significance in immunotherapy, such as chimeric antigen receptor T-cell therapy (CAR-T therapy). Methods: In this study, we first evaluated the immunophenotype changes of 31 de novo adult B-ALL patients who harbor ZNF384r and received chemotherapy from Nov 2020 to May 2023. Then, 49 r/r B-ALL patients who received the CD19 or CD19/CD22-based CAR-T infusion in our institute were included in the analysis to further investigate the prognosis effects of ZNF384r on CAR-T therapy. At the same time, the next-generation sequencing and RNA sequencing data of the patients with ZNF384r were analyzed to explore the potential mechanisms behind it. Results: First, we investigated the potential effects of ZNF384r in antigen editing after chemotherapy. Our results showed that 100% (31/31) of the patients express lymphoid lineage marker CD19 and 96.4% (27/28) of patients with CD22 expression at diagnosis. In addition, the majority of them had myeloid lineage marker expression, such as 96.2% (26/27) of patients with CD33 expression, and 96.5% with CD123 expression. After chemotherapy, 11 patients remained MRD positive after induction therapy, and 5 patients relapsed. In them, there were 18.8% (3/16) of patients lost CD19 expression, 12.5% of patients lost or reduced CD22 expression, while 100% of patients kept CD33 expression. For the adult r/r B-ALL patients who received the CD19 or CD19/CD22-based CAR-T infusion, there were 3 patients identified with EP300-ZNF384. Notably, all these three patients harboring ZNF384r relapsed within one year after the CAR-T therapy. Two of them experienced CD19-negative relapse, and one patient even had a myeloid transformation. These results indicated ZNF384r might associate with antigen editing during treatment-related selective pressures. The next-generation sequencing was performed in 25 B-ALL patients harboring ZNF384r before chemotherapy or CAR-T therapy, the results showed that in addition to CREBBP, NRAS, ETV6, NOTCH1/3, FLT3-ITD mutation was also the most common co-mutation with ZNF384r. Furthermore, the transcriptome analysis showed the Jak-STAT signaling pathway and the hematopoietic cell lineage pathway were highly enriched in the group with EP300::ZNF384 fusion compared with TCF3::PBX1 fusion. The expression of CD33, CD34, CD123, and IL5 were also significantly up-regulated in the EP300::ZNF384 group. All these results indicated ZNF384r might be involved in the regulation of the hematopoietic cell lineage differentiation pathway and myeloid lineage skewing. Conclusions: Our findings demonstrated that ZNF384 rearrangement might induce antigen editing during treatment-related selective pressures in adult B cell acute lymphoid leukemia, especially in CAR-T therapy. More efforts are needed to reveal mechanisms behind it to help reduce antigen loss and relapse rate after CAR-T therapy.

Regulation of Immune Checkpoint Antigen CD276 (B7-H3) on Human Placenta-Derived Mesenchymal Stromal Cells in GMP-Compliant Cell Culture Media.

Therapies utilizing autologous mesenchymal cell delivery are being investigated as anti-inflammatory and regenerative treatments for a broad spectrum of age-related diseases, as well as various chronic and acute pathological conditions. Easily available allogeneic full-term human placenta mesenchymal stromal cells (pMSCs) were used as a potential pro-regenerative, cell-based therapy in degenerative diseases, which could be applied also to elderly individuals. To explore the potential of allogeneic pMSCs transplantation for pro-regenerative applications, such cells were isolated from five different term-placentas, obtained from the dissected maternal, endometrial (mpMSCs), and fetal chorion tissues (fpMSCs), respectively. The proliferation rate of the cells in the culture, as well as their shape, in vitro differentiation potential, and the expression of mesenchymal lineage and stem cell markers, were investigated. Moreover, we studied the expression of immune checkpoint antigen CD276 as a possible modulation of the rejection of transplanted non-HLA-matched homologous or even xeno-transplanted pMSCs. The expression of the cell surface markers was also explored in parallel in the cryosections of the relevant intact placenta tissue samples. The expansion of pMSCs in a clinical-grade medium complemented with 5% human platelet lysate and 5% human serum induced a significant expression of CD276 when compared to mpMSCs expanded in a commercial medium. We suggest that the expansion of mpMSCs, especially in a medium containing platelet lysate, elevated the expression of the immune-regulatory cell surface marker CD276. This may contribute to the immune tolerance towards allogeneic pMSC transplantations in clinical situations and even in xenogenic animal models of human diseases. The endurance of the injected comparably young human-term pMSCs may promote prolonged effects in clinical applications employing non-HLA-matched allogeneic cell therapy for various degenerative disorders, especially in aged adults.

Translocator protein (18kDA) (TSPO) marks mesenchymal glioblastoma cell populations characterized by elevated numbers of tumor-associated macrophages

TSPO is a promising novel tracer target for positron-emission tomography (PET) imaging of brain tumors. However, due to the heterogeneity of cell populations that contribute to the TSPO-PET signal, imaging interpretation may be challenging. We therefore evaluated TSPO enrichment/expression in connection with its underlying histopathological and molecular features in gliomas. We analyzed TSPO expression and its regulatory mechanisms in large in silico datasets and by performing direct bisulfite sequencing of the TSPO promotor. In glioblastoma tissue samples of our TSPO-PET imaging study cohort, we dissected the association of TSPO tracer enrichment and protein labeling with the expression of cell lineage markers by immunohistochemistry and fluorescence multiplex stains. Furthermore, we identified relevant TSPO-associated signaling pathways by RNA sequencing.We found that TSPO expression is associated with prognostically unfavorable glioma phenotypes and that TSPO promotor hypermethylation is linked to IDH mutation. Careful histological analysis revealed that TSPO immunohistochemistry correlates with the TSPO-PET signal and that TSPO is expressed by diverse cell populations. While tumor core areas are the major contributor to the overall TSPO signal, TSPO signals in the tumor rim are mainly driven by CD68-positive microglia/macrophages. Molecularly, high TSPO expression marks prognostically unfavorable glioblastoma cell subpopulations characterized by an enrichment of mesenchymal gene sets and higher amounts of tumor-associated macrophages.In conclusion, our study improves the understanding of TSPO as an imaging marker in gliomas by unveiling IDH-dependent differences in TSPO expression/regulation, regional heterogeneity of the TSPO PET signal and functional implications of TSPO in terms of tumor immune cell interactions.

Characterization of Somatotrope Cell Expansion in Response to GHRH in the Neonatal Mouse Pituitary.

In humans and mice, loss-of-function mutations in growth hormone-releasing hormone receptor (GHRHR) cause isolated GH deficiency. The mutant GHRHR mouse model, GhrhrLit/Lit (LIT), exhibits loss of serum GH, but also fewer somatotropes. However, how loss of GHRH signaling affects expansion of stem and progenitor cells giving rise to GH-producing cells is unknown. LIT mice and wild-type littermates were examined for differences in proliferation and gene expression of pituitary lineage markers by quantitative reverse transcription polymerase chain reaction and immunohistochemistry at postnatal day 5 (p5) and 5 weeks. At p5, the LIT mouse shows a global decrease in pituitary proliferation measured by proliferation marker Ki67 and phospho-histone H3. This proliferative defect is seen in a pituitary cell expressing POU1F1 with or without GH. SOX9-positive progenitors show no changes in proliferation in p5 LIT mice. Additionally, the other POU1F1 lineage cells are not decreased in number; rather, we observe an increase in lactotrope cell population as well as messenger RNA for Tshb and Prl. In the 5-week LIT pituitary, the proliferative deficit in POU1F1-expressing cells observed neonatally persists, while the number and proliferative proportion of SOX9 cells do not appear changed. Treatment of cultured pituitary explants with GHRH promotes proliferation of POU1F1-expressing cells, but not GH-positive cells, in a mitogen-activated protein kinase-dependent manner. These findings indicate that hypothalamic GHRH targets proliferation of a POU1F1-positive cell, targeted to the somatotrope lineage, to fine tune their numbers.

Engineered neurogenesis in naïve adult rat cortex by Ngn2-mediated neuronal reprogramming of resident oligodendrocyte progenitor cells.

Adult tissue stem cells contribute to tissue homeostasis and repair but the long-lived neurons in the human adult cerebral cortex are not replaced, despite evidence for a limited regenerative response. However, the adult cortex contains a population of proliferating oligodendrocyte progenitor cells (OPCs). We examined the capacity of rat cortical OPCs to be re-specified to a neuronal lineage both in vitro and in vivo. Expressing the developmental transcription factor Neurogenin2 (Ngn2) in OPCs isolated from adult rat cortex resulted in their expression of early neuronal lineage markers and genes while downregulating expression of OPC markers and genes. Ngn2 induced progression through a neuronal lineage to express mature neuronal markers and functional activity as glutamatergic neurons. In vivo retroviral gene delivery of Ngn2 to naive adult rat cortex ensured restricted targeting to proliferating OPCs. Ngn2 expression in OPCs resulted in their lineage re-specification and transition through an immature neuronal morphology into mature pyramidal cortical neurons with spiny dendrites, axons, synaptic contacts, and subtype specification matching local cytoarchitecture. Lineage re-specification of rat cortical OPCs occurred without prior injury, demonstrating these glial progenitor cells need not be put into a reactive state to achieve lineage reprogramming. These results show it may be feasible to precisely engineer additional neurons directly in adult cerebral cortex for experimental study or potentially for therapeutic use to modify dysfunctional or damaged circuitry.

Clinicopathologic and Molecular Characterization of Anorectal Neuroendocrine Carcinomas Reveals Human Papillomavirus, p53, and c-Myc as Alternative Mechanisms of Carcinogenesis

Poorly differentiated neuroendocrine carcinomas (NECs) are rare malignant neoplasms with aggressive behavior. The diagnosis remains challenging due to ever-changing terminologies and morphologic overlaps with other disease entities. Herein, we seek to better define anorectal NECs by high-risk human papillomavirus (HPV) status and molecular profiling. Fourteen cases, including 3 men and 11 women with a median age of 63 years, were included. High-risk HPV RNA in situ hybridization was diffusely positive (+) in 7 cases, focal rarely positive (+/−) in 2 cases, and completely negative (−) in 5 cases. By morphology, all HPV(−) NECs were large-cell type, 3 mixed with a tubular adenoma/dysplasia or invasive adenocarcinoma. HPV-related (+ or +/−) NECs were mostly small-cell type, 3 mixed with squamous dysplasia and/or squamous cell carcinoma. Immunohistochemically, all NECs were positive for at least 2 neuroendocrine markers. The HPV(−) NECs were also positive for CDX2, whereas all HPV-related NECs were negative or only focally positive for CDX2, p40, and p63. Overexpression of p53 was found in 3 HPV(−) and 2 HPV(+/−) NECs but not in any HPV(+) NECs. Molecular analysis revealed MYC gene amplification in 4 cases: 2 HPV(−), 1 HPV(+/−), and 1 HPV(+). This was confirmed by fluorescence in situ hybridization in all but 1 HPV(−) NEC, which showed polysomy 8 but no true MYC amplification. Interestingly, only 2 of the 4 MYC amplification–bearing cases, both p53 normal/wild-type, expressed c-Myc protein by immunohistochemistry. The other 2 cases, both p53 overexpressed, did not show c-Myc expression despite true MYC amplification. Our study demonstrates that anorectal NECs arise in HPV-dependent or -independent pathways, with heterogeneous expression of other lineage markers and different molecular signatures. Expressions of p53 and c-Myc proteins appear to be mutually exclusive regardless of HPV status, likely mediating alternative mechanisms of NEC carcinogenesis.

Asbestos accelerates disease onset in a genetic model of malignant pleural mesothelioma.

Hypothesis: Asbestos-driven inflammation contributes to malignant pleural mesothelioma beyond the acquisition of rate-limiting mutations. Methods: Genetically modified conditional allelic mice that were previously shown to develop mesothelioma in the absence of exposure to asbestos were induced with lentiviral vector expressing Cre recombinase with and without intrapleural injection of amosite asbestos and monitored until symptoms required euthanasia. Resulting tumours were examined histologically and by immunohistochemistry for expression of lineage markers and immune cell infiltration. Results: Injection of asbestos dramatically accelerated disease onset and end-stage tumour burden. Tumours developed in the presence of asbestos showed increased macrophage infiltration. Pharmacological suppression of macrophages in mice with established tumours failed to extend survival or to enhance response to chemotherapy. Conclusion: Asbestos-driven inflammation contributes to the severity of mesothelioma beyond the acquisition of rate-limiting mutations, however, targeted suppression of macrophages in established epithelioid mesothelioma showed no therapeutic benefit.

In Vitro-Produced Equine Blastocysts Exhibit Greater Dispersal and Intermingling of Inner Cell Mass Cells than In Vivo Embryos.

In vitro production (IVP) of equine embryos is increasingly popular in clinical practice but suffers from higher incidences of early embryonic loss and monozygotic twin development than transfer of in vivo derived (IVD) embryos. Early embryo development is classically characterized by two cell fate decisions: (1) first, trophectoderm (TE) cells differentiate from inner cell mass (ICM); (2) second, the ICM segregates into epiblast (EPI) and primitive endoderm (PE). This study examined the influence of embryo type (IVD versus IVP), developmental stage or speed, and culture environment (in vitro versus in vivo) on the expression of the cell lineage markers, CDX-2 (TE), SOX-2 (EPI) and GATA-6 (PE). The numbers and distribution of cells expressing the three lineage markers were evaluated in day 7 IVD early blastocysts (n = 3) and blastocysts (n = 3), and in IVP embryos first identified as blastocysts after 7 (fast development, n = 5) or 9 (slow development, n = 9) days. Furthermore, day 7 IVP blastocysts were examined after additional culture for 2 days either in vitro (n = 5) or in vivo (after transfer into recipient mares, n = 3). In IVD early blastocysts, SOX-2 positive cells were encircled by GATA-6 positive cells in the ICM, with SOX-2 co-expression in some presumed PE cells. In IVD blastocysts, SOX-2 expression was exclusive to the compacted presumptive EPI, while GATA-6 and CDX-2 expression were consistent with PE and TE specification, respectively. In IVP blastocysts, SOX-2 and GATA-6 positive cells were intermingled and relatively dispersed, and co-expression of SOX-2 or GATA-6 was evident in some CDX-2 positive TE cells. IVP blastocysts had lower TE and total cell numbers than IVD blastocysts and displayed larger mean inter-EPI cell distances; these features were more pronounced in slower-developing IVP blastocysts. Transferring IVP blastocysts into recipient mares led to the compaction of SOX-2 positive cells into a presumptive EPI, whereas extended in vitro culture did not. In conclusion, IVP equine embryos have a poorly compacted ICM with intermingled EPI and PE cells; features accentuated in slowly developing embryos but remedied by transfer to a recipient mare.

LPS-induced inflammation potentiates dental pulp stem cell odontogenic differentiation through C5aR and p38

ABSTRACT Aim Inflammation is a complex host response to harmful infection or injury, and it seems to play a crucial role in tissue regeneration both positively and negatively. We have previously demonstrated that the activation of the complement C5a pathway affects dentin-pulp regeneration. However, limited information is available to understand the role of the complement C5a system related to inflammation-mediated dentinogenesis. The aim of this study was to determine the role of complement C5a receptor (C5aR) in regulating lipopolysaccharide (LPS)-induced odontogenic differentiation of dental pulp stem cells (DPSCs). Material and Methods Human DPSCs were subjected to LPS-stimulated odontogenic differentiation in dentinogenic media treated with the C5aR agonist and antagonist. A putative downstream pathway of the C5aR was examined using a p38 mitogen-activated protein kinase (p38) inhibitor (SB203580). Results Our data demonstrated that inflammation induced by the LPS treatment potentiated DPSC odontogenic differentiation and that this is C5aR dependent. C5aR signaling controlled the LPS-stimulated dentinogenesis by regulating the expression of odontogenic lineage markers like dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP-1). Moreover, the LPS treatment increased the total p38, and the active form of p38 expression, and treatment with SB203580 abolished the LPS-induced DSPP and DMP-1 increase. Conclusions These data suggest a significant role of C5aR and its putative downstream molecule p38 in the LPS-induced odontogenic DPSCs differentiation. This study highlights the regulatory pathway of complement C5aR/p38 and a possible therapeutic approach for improving the efficiency of dentin regeneration during inflammation.

Blockage of retinoic acid signaling via RARγ suppressed the proliferation of pancreatic cancer cells by arresting the cell cycle progression of the G1-S phase

BackgroundOur study and several studies have reported that in some cancers, including pancreatic ductal adenocarcinoma (PDAC), the expression of squamous lineage markers, such as esophagus-tissue-specific genes, correlated with a poor prognosis. However, the mechanism by which the acquisition of squamous lineage phenotypes leads to a poor prognosis remains unclear. We previously reported that retinoic acid signaling via retinoic acid receptor γ (RARγ signaling) determines the differentiation lineage into the esophageal squamous epithelium. These findings hypothesized that the activation of RARγ signaling contributed to acquiring squamous lineage phenotypes and malignant behavior in PDAC.MethodsThis study utilized public databases and immunostaining of surgical specimens to examine RARγ expression in PDAC. We evaluated the function of RARγ signaling by inhibitors and siRNA knockdown using a PDAC cell line and patient-derived PDAC organoids. The mechanism of the tumor-suppressive effects by blocking RARγ signaling was examined by a cell cycle analysis, apoptosis assays, RNA sequencing and Western blotting.ResultsRARγ expression in pancreatic intraepithelial neoplasia (PanIN) and PDAC was higher than that in the normal pancreatic duct. Its expression correlated with a poor patient prognosis in PDAC. In PDAC cell lines, blockade of RARγ signaling suppressed cell proliferation by inducing cell cycle arrest in the G1 phase without causing apoptosis. We demonstrated that blocking RARγ signaling upregulated p21 and p27 and downregulated many cell cycle genes, including cyclin-dependent kinase 2 (CDK2), CDK4 and CDK6. Furthermore, using patient-derived PDAC organoids, we confirmed the tumor-suppressive effect of RARγ inhibition and indicated the synergistic effects of RARγ inhibition with gemcitabine.ConclusionsThis study clarified the function of RARγ signaling in PDAC progression and demonstrated the tumor-suppressive effect of selective blockade of RARγ signaling against PDAC. These results suggest that RARγ signaling might be a new therapeutic target for PDAC.

Effects of cannabidiol on the differentiation of human monocytes into macrophages

Abstract Background: Innate immune myeloid cells, such as macrophages, contribute to chronic inflammation when consistently activated. Recently, cannabidiol (CBD), an active non-psychoactive constituent of the Cannabis sativa plant (i.e., Marijuana), has sparked interest as a safe and effective anti-inflammatory and immunomodulatory agent. This study aimed to investigate the CBD’s effects on the differentiation of human macrophages and their cell surface receptors. Methods: Peripheral blood was collected from healthy human donors. Monocytes, isolated from peripheral blood mononuclear cells, were differentiated with macrophage colony stimulating factor into monocyte-derived macrophages (MDM) with and without CBD (5 μM). Differentiated MDMs were then stained for different cell surface markers and analyzed by multicolor flow-cytometry. Proportions of anti-inflammatory (M2: CD206, CD71, CD163) and pro-inflammatory (M1: CD86, CD163) MDMs, and expression of myeloid lineage markers (CD14, CD16), chemokine receptor 5 (CCR5) and endocannabinoid type 2 receptor (CB2) were determined. Results: CBD promoted a shift towards a greater proportion of M2-type vs. M1-type MDMs (p<0.05, Fisher’s exact test). Cells displayed a significantly reduced expression of CD14, CD163, CD86, CCR5 and CB2 (p<0.05, Student t-test). Conclusions: CBD appears to promote differentiation of MDMs into anti-inflammatory phenotypes. Further studies are ongoing to determine the mechanistic pathways implicated in these processes, as these findings may have implications for the use of CBD in various disease conditions.

Abstract SY33-02: Novel molecular mechanisms of lung cancer plasticity and targeting lung squamous cell carcinoma

Abstract Lung cancer is marked by a high degree of genetic and histopathological heterogeneity. Lineage plasticity, the ability of cells to transform from one cell type to another, has been associated with intratumoral heterogeneity and therapeutic resistance. The molecular drivers and mechanisms of cancer cell plasticity and histological transdifferentiation of lung cancer are largely unknown. A deubiquitinating enzyme, Ubiquitin-Specific Peptidase 13 (USP13), is frequently amplified at chromosome 3q.26 amplicon in lung squamous cell carcinoma. USP13 knock-in overexpressing mouse model was crossed with KrasLSL-G12D; Trp53fl/fl (KP) mouse to generate KrasLSL-G12D; Trp53fl/fl; Usp13LSL (KPU) mouse model. Intratracheal administration of adenovirus expressing Cre recombinase to the lung of the KPU mouse developed aggressive lung tumors and a shortened survival compared to the KP mouse model. Importantly, while the KP mice developed lung adenocarcinoma, 100% of KPU mice developed lung squamous cell carcinoma. The squamous cell carcinoma of the KPU mice faithfully mimicked the molecular signatures, cellular pathways, and tumor microenvironments of human lung squamous cell carcinoma. Delivery of cell type-restricted viruses to the lungs further identified bronchiolar secretory club cells as the predominant cell-of-origin of KPU-induced lung squamous cell carcinoma. USP13 altered the levels of TTF-1 and c-Myc in club cells of the airway and reinforced the fate of CC10+ club cells to squamous carcinoma development instead of adenocarcinoma. USP13 directly acted on the K48-linked ubiquitination of c-Myc and increased the protein stability of c-Myc in human lung cancer cells. Overexpression of USP13 increased the half-life of c-Myc while inhibiting USP13 deubiquitinase activity decreased the c-Myc protein level. USP13 upregulated the expression of squamous lineage markers (Sox2, CK5, P40) in the primary mouse and advanced human lung cancer cells. Our findings revealed that USP13 promotes the lineage plasticity of origin-of-cells of the lung and drives transdifferentiation to squamous cell carcinoma. Finally, our study suggests the critical role of USP13 in unlocking the phenotypic plasticity of lung cancer, which may lead to novel therapeutics targeting lung cancer. Citation Format: Cecil Han. Novel molecular mechanisms of lung cancer plasticity and targeting lung squamous cell carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr SY33-02.

Abstract 6736: Suppression of antigen presentation is a hallmark of pediatric rhabdomyosarcoma

Abstract Background: Rhabdomyosarcoma (RMS) is the most common soft tissue tumor in children and young adults, accounting for approximately 350-400 new cases annually in the US. These tumors are diagnosed based on their expression of skeletal muscle lineage markers. Clinical trials testing conventional immunotherapies such as cancer vaccines or immune checkpoint blockade (ICB) therapy have found no activity in RMS, although the root causes of failure are largely unexplored. A recent study by our group found that RMS tumors have a lack of immune infiltrate, consistent with previous reports. However, we made an unexpected observation that RMS tumors had a near absence of antigen processing and presentation (APP) gene expression, a key requisite for anti-tumor CD8+ T lymphocytes. In this study, we investigate the root causes of the lack of APP in RMS and evaluate implications for immunotherapy. Methods: Publicly available DNA sequencing datasets were used to evaluate APP gene mutations in RMS tumor samples. RNAseq from reporter iPSC cell lines demarcating specific stages of skeletal muscle differentiation were used to evaluate APP gene expression during myogenesis. Surface MHC class I expression was evaluated using flow cytometry against a panel of pediatric sarcoma cell lines. RMS PDX and cell line APP protein levels were measured by western blot. Stimulation of APP in RMS cell lines was tested using IFNγ or sub-cytotoxic doses of different epigenetic therapeutics (DNMTi, HDACi, EZH2i) before analyzing surface MHC class I expression by flow cytometry. Results: RNAseq analysis of the differentiation states across the normal human skeletal muscle lineage revealed a myoblastic cell state which transiently downregulates the APP pathway. RNA expression of HLA-A,B,C genes were lower in RMS than any other pediatric extracranial solid tumor histology studied. RMS cell lines and PDX models also displayed low APP pathway gene expression by western blot and flow cytometry, with FOXO1 fusion positive RMS having a near absence of expression. RMS tumor exome sequencing data from RMS patients showed a lack of enrichment of APP gene mutations. Instead, we found that APP could be induced in nearly all samples tested using IFNγ or epigenetic stimulation with Decitabine, Entinostat, or Tazemetostat. Conclusions: We uncovered a previously unappreciated lack of antigen presentation in RMS which phenocopies myoblasts in normal skeletal muscle development. The downregulation of MHC class I antigen presentation is not due to APP pathway mutations but rather a partially reversible downregulation mirroring this specific stage of normal skeletal muscle development. Our findings suggest that pharmacological reversal of the APP pathway downregulation may enhance immunotherapies targeting MHC class I antigens in RMS. Citation Format: David Milewski, Meijie Tian, Yong Kim, Jun Wei, Javed Khan. Suppression of antigen presentation is a hallmark of pediatric rhabdomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6736.

Cross-species comparison of mouse and human preimplantation development with an emphasis on lineage specification.

Human embryogenesis still remains largely unexplored. This review helps identify some of our current gaps in knowledge pertaining to preimplantation development, which may have implications for understanding fundamental aspects of human development, assisted reproductive technologies, and stem cell biology. Preimplantation development is arguably one of the most critical stages of embryogenesis. Beginning with the formation of the totipotent zygote post-fertilization, a series of cell divisions, and a complex coordination of physical cues, molecular signals and changes in gene expression lead to the formation of the blastocyst, a structure capable of implanting into the uterine wall. The blastocyst is composed of more specified cellular lineages, which will give rise to every tissue of the developing organism as well as the extra-embryonic lineages which support fetal growth. While the mouse has been used as a model to understand the events of preimplantation development for decades, in recent years, an expanding body of work has been conducted using the human embryo. These studies have identified some crucial species differences, particularly in the transcriptional and spatio-temporal expression of lineage markers and responses to cell signaling perturbations. This review compares recent findings on preimplantation development in mouse and human, with a focus on the specification of the first cellular lineages. Highlighting differences and noting mechanisms that require further examination in the human embryo is of critical importance for both the accurate translation of results from the mouse model and our overall understanding of mammalian development. We further highlight the latest advancement in reproductive research, the development of the 3D stem cell-based models known as 'blastoids'. The knowledge discussed in this review has major clinical implications for assisted reproductive technologies such as in vitro fertilization and for applications in stem cell biology.

Abstract B024: Deconvolution by scRNAseq, scATACseq and functional genomics of impact of a relevant high risk diet on stem cells and homeostasis

Abstract Dietary patterns are major determinants of sporadic colon cancer incidence, the vast majority of the disease. NWD1 is a unique purified rodent diet that establishes mouse exposure to key nutrients recapitulating levels linked to higher risk in human, and is the only mouse model that develops sporadic intestinal and colon tumors, reflecting the etiology, incidence, frequency and lag with developmental age of the human disease. NWD1 fed mice reflect human metabolic syndrome with chronic inflammation, exhibit elevated Wnt signaling throughout the small and large intestinal mucosa and altered lineage marker expression, but Lgr5hi cells are suppressed in their lineage tracing, accumulation of mutations, and efficiency in tumor initiation. Alternate cells are mobilized to maintain the mucosa with increased efficiency to cause tumors. Deconvolving impact of NWD1 using scRNAseq, scATACseq and functional genomics provided novel insight into mechanisms elevating risk for sporadic tumors. NWD1 extensively, rapidly, and reversibly reprogrammed Lgr5hi stem cells, down-regulating Ppargc1a expression that altered mitochondrial structure and function and suppressed Oxphos and the TCA cycle. Ppargc1a genetic knockout in Lgr5hi cells recapitulated the dietary effects, and NWD1 or Ppargc1a inactivation repressed developmental maturation of Lgr5hi cell progeny as cells progressed through progenitor cell compartments. In compensation, mobilized Bmi1+, Ascl2hi cells maintained and adapted the mucosa. In parallel, NWD1 altered Ppargc1a chromatin structure in stem cells, and also for genes adapting enterocytes to the diet, independently confirming NWD1 epigenetic reprogramming of stem and differentiated cells. Importantly, pathways of antigen processing and presentation were elevated, especially in mature enterocytes, a pathogenic mechanism causing human chronic low-level pro-tumorigenic inflammation in IBD, also present in NWD1 fed mice. Fundamental conclusions: 1) plasticity of cells to function as stem cells mediates physiological adaptation of the mucosa. Thus, the human mucosa is in constant flux in response to its environment, supporting historic concepts of homeostasis by Claude Bernard and Walter Cannon as a continual process of tissue adaptation to its environment, not a single optimized state. 2) our data and the literature suggest that failure to recapitulate key human nutritional exposures contributes to why human stem cells reach crypt clonality in 6 years, 50-fold longer than the 6 weeks in the mouse. Thus, better modeling of human nutritional exposures in the mouse more accurately reflects human mechanisms of homeostasis and pathogenesis. 3) Complexity of cell reprogramming reported for the earliest premalignant human colon tumors is already present in the mucosa at nutritional risk for tumor development. 4) Oncogenic mutations provide a competitive advantage to intestinal stem cells in tumorigenesis, but the competition takes place on a playing field sculpted by the nutritional environment, a major determinant of who wins. Citation Format: Jiahn Choi, Xusheng Zhang, Wenge Li, Michele Houston, Karina Peregrina, Robert Dubin, Kenny Ye, Leonard H. Augenlicht. Deconvolution by scRNAseq, scATACseq and functional genomics of impact of a relevant high risk diet on stem cells and homeostasis [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr B024.