Thy-1 Expression Research Articles

DNAR-08. THY1 MEDIATES TREATMENT RESISTANCE IN GLIOBLASTOMA THROUGH RAPID REPAIR OF DNA DAMAGE

Abstract Glioblastoma (GBM) is a uniformly lethal primary intracranial neoplasm that inevitably recurs despite treatment by DNA damaging agents radiation (RT) and temozolomide (TMZ). Recurrence may be driven by inherently resistant glioma stem-like cells (GSCs). GSCs have been shown to have constitutive upregulation of DNA damage response (DDR) pathways, resulting from elevated DNA replication stress. This baseline elevated DDR has consequently been shown to confer inherent resistance to DNA damaging agents, TMZ/RT. However, factors mediating elevated replication stress and upregulated DDR in GSCs are poorly defined. Previously, we identified the cell-surface protein, THY1, as a mediator of GSC phenotype and treatment resistance in GBM. To determine mechanisms mediating treatment resistance in THY1+ cells, we engineered patient-derived neurosphere and organoid models, to either overexpress or silence THY1 expression. These models were treated with RT and collected at various time points to measure DNA repair efficiency by assessing the formation and resolution of yH2AX foci and ATM/ATR activation. In parallel, patient-derived GBM tissue from over 20 patients was analyzed using single cell RNA sequencing and spatial transcriptomics to assess pathways associated with THY1 expression. Interestingly, spatial transcriptomics and single cell RNA sequencing data demonstrates significant upregulation of GSC pathways, as well as constitutive upregulation of DDR pathways (p<2e-16) in THY1-high cells. Exploiting our patient-derived lines we determined that DNA repair activation was upregulated at baseline, measured using yH2AX foci and immunoblotting. We then measured DDR in response to radiation and found that high THY1 expression mediated rapid repair of DNA. Overall, we demonstrate that THY1 mediates therapy resistance by constitutively upregulating DDR, likely by upregulating DNA replication stress. We are now working to determine the mechanisms mediating the GSC phenotype and DNA replication stress in THY1 cells in hopes of future translation.

STEM-10. NEURAL PROGENITOR CELL MARKERS IN IDH MUTANT AND IDHWT GLIOMAS

Abstract INTRODUCTION Single-cell RNA sequencing (scRNA-seq) has helped to elucidate the cellular composition of cancer and its microenvironment. Recent scRNA-seq studies have highlighted the heterogeneity of glioblastoma (GBM). Moreover, single-cell GBM analyses have proposed resemblance of GBM cells to radial glia and outer radial glia, supporting the hypothesis that remnants of developmental tissue get reactivated in cancer. A recent study isolated neural progenitor cells (NPCs) from developing fetal human brain (gestational week 17–19) and classified NPCs based on their expression of THY1, CD24 and EGFR. Ventricular radial glia are THY1- CD24-EGFR+ whereas outer radial glia are THY1- CD24-EGFR-. Early neuron precursors are CD24+THY1-EGFR+ and glial progenitor cells (GPCs) are THY1+EGFR+. GPCs give rise to THY1+EGFR+PDGFRA+ pre-oligodendrocyte progenitor cells. The importance of EGFR in NPCs again highlights the resemblance to glioma. METHODS We aimed to apply the classification above to IDH mutant astrocytoma and oligodendroglioma as well as IDHwt glioblastoma samples. We used three publicly available datasets: Wang (paired 74 IDHwt primary and recurrent samples), Tirosh (6 primary oligodendroglioma samples) and Venteicher (10 primary IDH mutant astrocytoma). RESULTS In IDH mutant astrocytoma, 82.63% of cells express THY1+ (mostly EGFR+PDGFRA+) and 10.76% of cells are THY1-CD24-EGFR+. In oligodendroglioma, 75% of cells are THY1+ (mostly EGFR+PDGFRA+) and 12.07% are THY1-CD24-EGFR+. In IDHwt EGFR amplified primary GBM samples, 87.5% of cells are THY1-CD24-EGFR+. This percentage drops to 70.4% in the recurrent setting. THY1-CD24-EGFR- cells increase from 9.7% to 23.1% at recurrence. In IDHwt EGFRwt primary GBM samples, 48.6% of cells are THY1-CD24-EGFR+ and 44.15% are THY1-CD24-EGFR-. In the recurrent setting, 43.26% of cells are THY1-CD24-EGFR+ and 49.58% are THY1-CD24-EGFR-. CONCLUSION IDH mutant gliomas and IDHwt glioblastoma express different progenitor cell markers and may have a different cell of origin. THY1 is highly expressed in IDH mutant gliomas.

Experimental study on treatment of retinitis pigmentosa by inducing Müller cell reprogramming with Lycii Fructus and Salviae Miltiorrhizae Radix et Rhizoma

This study aims to explore the effect of Lycii Fructus and Salviae Miltiorrhizae Radix et Rhizoma(LFSMR), a drug pair possesses the function of nourishing Yin, promoting blood circulation, and brightening the eyes, in treating retinitis pigmentosa(RP)by inhibiting the gliosis of Müller cells(MCs) and inducing their reprogramming and differentiation into various types of retinal nerve cells. Twelve C57 mice were used as the normal control group, and 48 transgenic RP(rd10) mice were randomly divided into the model group, positive control group, and low and high dose LFSMR groups, with 12 mice in each group. HE staining was used to detect pathological changes in the retina, and an electroretinogram was used to detect retinal function. Retinal optical coherence tomography was used to detect retinal thickness and perform fundus photography, and laser speckle perfusion imaging was used to detect local retinal blood flow. Digital PCR was used to detect gene expression related to retinal nerve cells, and immunofluorescence was used to detect protein expression related to retinal nerve cells. LFSMR could significantly improve the pathological changes, increase the amplitude of a and b waves, increase the retinal thickness, restore retinal damage, and increase retinal blood flow in mice with RP lesions. LFSMR could also significantly inhibit the m RNA expression of the glial fibrillary acidic protein( GFAP) during the pathogenesis of RP and upregulate m RNA expression of sex determining region Y box protein 2(SOX2), paired box protein 6(Pax6),rhodopsin, protein kinase C-α(PKCα), syntaxin, and thymic cell antigen 1. 1(Thy1. 1). LFSMR could significantly inhibit GFAP protein expression and enhance protein expression of SOX2, Pax6, rhodopsin, PKCα, syntaxin, and Thy1. 1. It could also reverse the pathological changes in the retina of rd10 mice, improve retinal function and fundus performance, increase retinal thickness, enhance local retinal blood flow, and exert therapeutic effects on RP. The mechanism of action of LFSMR may be related to inhibiting the gliosis of MCs and promoting their reprogramming and differentiation into various types of retinal nerve cells.

Cell Heterogeneity Analysis Revealed the Key Role of Fibroblasts in the Magnum Regression of Ducks.

Duck egg production, like that of laying hens, follows a typical low-peak-low cycle, reflecting the dynamics of the reproductive system. Post-peak, some ducks undergo a cessation of egg laying, indicative of a regression process in the oviduct. Notably, the magnum, being the longest segment of the oviduct, plays a crucial role in protein secretion. Despite its significance, few studies have investigated the molecular mechanisms underlying oviduct regression in ducks that have ceased laying eggs. In this study, we conducted single-cell transcriptome sequencing on the magnum tissue of Shaoxing ducks at 467 days of age, utilizing the 10× Genomics platform. This approach allowed us to generate a detailed magnum transcriptome map of both egg-laying and ceased-laying ducks. We collected transcriptome data from 13,708 individual cells, which were then subjected to computational analysis, resulting in the identification of 27 distinct cell clusters. Marker genes were subsequently employed to categorize these clusters into specific cell types. Our analysis revealed notable heterogeneity in magnum cells between the egg-laying and ceased-laying ducks, primarily characterized by variations in cells involved in protein secretion and extracellular matrix (ECM)-producing fibroblasts. Specifically, cells engaged in protein secretion were predominantly observed in the egg-laying ducks, indicative of their role in functional albumen deposition within the magnum, a phenomenon not observed in the ceased-laying ducks. Moreover, the proportion of THY1+ cells within the ECM-producing fibroblasts was found to be significantly higher in the egg-laying ducks (59%) compared to the ceased-laying ducks (24%). Similarly, TIMP4+ fibroblasts constituted a greater proportion of the ECM-producing fibroblasts in the egg-laying ducks (83%) compared to the ceased-laying ducks (58%). These findings suggest a potential correlation between the expression of THY1 and TIMP4 in ECM-producing fibroblasts and oviduct activity during functional reproduction. Our study provides valuable single-cell insights that warrant further investigation into the biological implications of fibroblast subsets in the degeneration of the reproductive tract. Moreover, these insights hold promise for enhancing the production efficiency of laying ducks.

Abstract 291: Unveiling heterogeneity of cancer-associated fibroblasts (CAFs) across multiple solid cancer types

Abstract Background: Stromal cells, including CAFs, are a heterogeneous group of cells in the tumor microenvironment. Many models describe their heterogeneity like the classification into 3 main subtypes in breast cancer: myCAF (myofibroblasts), iCAF (inflammatory CAF), and PVL (perivascular-like) cells. However, a pan-cancer model has not been established to exhaustively characterize stromal cell heterogeneity, undermining efforts in targeting CAFs with anti-tumor therapies. We investigated the heterogeneity of stromal cells in diverse diagnoses with single-cell RNA sequencing (scRNA-seq) data and bulk RNA-seq of sorted stromal cells to define consistent subtypes. Design: First, a meta-cohort of 11 scRNA-seq open-source datasets (>500,000 cells, >100 patients, 6 diagnoses) was analyzed. We also generated a scRNA-seq dataset of CD90+ cells derived from tumor tissue of an ovarian cancer patient. Additionally, bulk RNA-seq of 6 PVL, 2 iCAF, and 4 myCAF sorted cell samples across four solid cancers was performed. scRNA-seq data was analyzed with the SCANPY Python package. Results: Stromal cell clusters were defined as positive for PDGFRB, THY1 (CD90), and COL1A1 expression, and negative for the expression of known non-stromal and endothelial cell markers, by separately analyzing the open-source scRNA-seq datasets. Analysis of stromal cell heterogeneity revealed that the CAFs were consistently classified into 3 subtypes across all datasets: myCAF (high expression: FAP and ACTA2), PVL (high expression: MCAM (CD146) and ACTA2), and iCAF (high expression: APOD and cytokines IL6, CXCL12, CXCL2). Differential gene expression analysis of the scRNA-seq meta-cohort allowed us to develop functional gene expression signatures to define each subtype. All scRNA-sequenced CD90+ cells from ovarian cancer tissue were classified into the CAF subtypes. The myCAF and PVL signatures were specifically upregulated in the corresponding cell types (p<0.01, Mann-Whitney U test). While the iCAF signature was enriched in both iCAFs and myCAFs, myCAF and PVL signatures were downregulated in iCAFs. Finally, we developed a fluorescence-activated cell sorting (FACS) panel to separate CAF subtypes, using negative markers (CD45, CD31, EPCAM), a positive marker for stromal cells (CD90) and cell-type surface markers (CD146, FAP, CD91, CD44) for myCAF, iCAF and PVL cells. The high expression of CAF-specific genes in the sorted CAF populations denoted high sample purity. Importantly, the 3 CAF subpopulations separated by gating based on different levels of cell-type surface markers showed expression patterns congruent with the developed signatures across diagnoses. Summary: Altogether, the consistent classification of stromal cells with our cell-specific expression profiles demonstrated that the 3 CAF subtypes are conserved in many cancer types, offering groundwork for a pan-cancer model of stromal cell heterogeneity. Citation Format: Andrey Kravets, Boris Shpak, Anastasia Zotova, Maria Savchenko, Sofya Kust, Olga Golubeva, Mary Abdou, Fedor Grigoryev, Irina Bulusheva, Beniamin Sargsyan, Polina Pavlovich, Vlad Maximov, Vladimir Kushnarev, Michael Goldberg, Nikita Kotlov, Alexander Bagaev. Unveiling heterogeneity of cancer-associated fibroblasts (CAFs) across multiple solid cancer types [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 291.

Screening of differentially expressed genes in gastric cancer based on GEO database and function and pathway enrichment analysis

To explore the core genes related to the diagnosis and prognosis of gastric cancer (GC) based on Gene Expression Omnibus (GEO) database and screen the molecular targets involved in the occurrence and development of GC. GC microarray data GSE118916, GSE54129 and GSE79973 were downloaded from GEO database, and the differentially expressed genes (DEGs) were screened. Enrichment analysis of the signaling pathways and molecular functions were preformed and protein-protein interaction networks (PPI) were constructed to identify the hub genes, whose expression levels and diagnostic and prognostic values were verifies based on gastric adenocarcinoma data from TCGA. The expression levels of these core genes were also detected in different GC cell lines using qRT- PCR. Seventy-seven DEGs were identified, which encodes proteins located mainly in the extracellular matrix and basement membrane with activities of oxidoreductase and extracellular matrix receptor and ligand, involving the biological processes of digestion and hormone metabolism and the signaling pathways in retinol metabolism and gastric acid secretion. Nine hub genes were obtained, among which SPARC, TIMP1, THBS2, COL6A3 and THY1 were significantly up- regulated and TFF1, GKN1, TFF2 and PGC were significantly down-regulated in GC. The abnormal expressions of SPARC, TIMP1, THBS2, COL6A3, TFF2 and THY1 were significantly correlated with the survival time of GC patients. ROC curve analysis showed that aberrant expression of TIMP1 SPARC, THY1 and THBS2 had high diagnostic value for GC. High expressions of SPARC, TIMP1, THBS2 and COL6A3 were detected in GC tissues. In the GC cell lines, qRT- PCR revealed different expression patterns of these hub genes, but their expressions were largely consistent with those found in bioinformatics analyses. SPARC, TIMP1, THBS2 and other DEGs are probably involved in GC occurrence and progression and may serve as potential candidate molecular markers for early diagnosis and prognostic evaluation of GC.

Abstract B001: Glioblastoma evolution and resistance is mediated by a shift in cell state and tumor microenvironmental interactions

Abstract Glioblastoma (GBM) is a lethal disease characterized by inevitable recurrence. Recently, single cell sequencing studies of primary GBM have defined various tumor cell states, specifically the neural progenitor-like (NPC-like), oligodendrocyte progenitor (OPC-like), astrocyte-like(AC-like), and mesenchymal(MES-like) states. Yet, the role these cell states play in treatment resistance and recurrence is not well defined. Furthermore, the spatial tumor microenvironmental (TME) context of tumor cells clearly plays a role in treatment response. Here we utilize in vivo recurrence models, and single cell and spatial transcriptomic (ST) analyses of primary and recurrent GBM to determine the pathways and spatial TME interactions mediating recurrence. Experimental Design: To define the evolution of the tumor landscape from primary to recurrence, we performed single cell RNA sequencing from stereotactically resected primary GBM (178K cells from 26 patients) and at recurrence (170K cells from 12 patients). ST analyses were also completed, as well as in vitro and in vivo mechanistic studies. Results: We identified a notable shift in the proportion of cell states in response to treatment from primary to recurrence with a significant decrease in AC-like cells (72% vs 55%, p<2e-16) and increase in MES-like cells (15% vs 34%, p<2e-16). This suggests that AC-like cells may be more treatment sensitive compared to other cell states, especially MES-like cells. We then worked to define potential TME interactions of these cell states to define drivers of recurrence. ST analyses revealed NPC-like cells in the infiltrative edge, AC-like cells in the tumor core, and MES-like cells in the hypoxic zones. We performed pseudotime trajectory analysis which identified that NPC-like cells divided into 2 daughter lineages: 1) AC-like cells which form the bulk of primary tumors and 2) MES-like cells that make up a large proportion of the recurrence. We then found that THY1, a cell surface receptor, was highly expressed in NPC-like cells in the primary tumors. While at recurrence, there was a remarkable increase in THY1 expression coincident with a switch to a predominantly MES-like state. Furthermore, ST analyses revealed upregulation of stem-like pathways in THY1 regions, as well as co-localization of MES-like THY1 cells with monocytes in hypoxic zones(p<0.001), suggesting an important role for TME interactions in mediating recurrence. To assess the biological implications of THY1, subsequent in vitro and in vivo studies revealed that THY1 knockout significantly decreased cell proliferation and tumor volume, and improved treatment response suggesting an important role for THY1 in driving treatment resistance and inevitable recurrence. Conclusions: Utilizing mechanistic and bioinformatic analyses, we show that a small population of NPC and MES-like THY1+ cells in primary GBM is likely to survive chemoradiation and mediate recurrence. Defining the interactions of these cell states in their TME and the mechanistic underpinnings of THY1 interactions may be critical to identifying new treatments. Citation Format: Sunita Shankar, Visweswaran Ravikumar, Arushi Tripathy, Sunjong Ji, Jackson Loper, Zainab Hassan, Ziad Fehmi, Yacoub Haydin, Dah-Luen Huang, Sagnik Bhadury, Reva Kulkarni, Jeffrey Regier, Daniel Wahl, Arvind Rao, Alnawaz Rehemtulla, Wajd N. Al-Holou. Glioblastoma evolution and resistance is mediated by a shift in cell state and tumor microenvironmental interactions [abstract]. In: Proceedings of the AACR Special Conference on Brain Cancer; 2023 Oct 19-22; Minneapolis, Minnesota. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_1):Abstract nr B001.

Increased Anti-Inflammatory Therapeutic Potential and Progenitor Marker Expression of Corneal Mesenchymal Stem Cells Cultured in an Optimized Propagation Medium.

There is a huge unmet need for new treatment modalities for ocular surface inflammatory disorders (OSIDs) such as dry eye disease and meibomian gland dysfunction. Mesenchymal stem cell therapies may hold the answer due to their potent immunomodulatory properties, low immunogenicity, and ability to modulate both the innate and adaptive immune response. MSC-like cells that can be isolated from the corneal stroma (C-MSCs) offer a potential new treatment strategy; however, an optimized culture medium needs to be developed to produce the ideal phenotype for use in a cell therapy to treat OSIDs. The effects of in vitro expansion of human C-MSC in a medium of M199 containing fetal bovine serum (FBS) was compared to a stem cell medium (SCM) containing knockout serum replacement (KSR) with basic fibroblast growth factor (bFGF) and human leukemia inhibitory factor (LIF), investigating viability, protein, and gene expression. Isolating populations expressing CD34 or using siRNA knockdown of CD34 were investigated. Finally, the potential of C-MSC as a cell therapy was assessed using co-culture with an in vitro corneal epithelial cell injury model and the angiogenic effects of C-MSC conditioned medium were evaluated with blood and lymph endothelial cells. Both media supported proliferation of C-MSC, with SCM increasing expression of CD34, ABCG2, PAX6, NANOG, REX1, SOX2, and THY1, supported by increased associated protein expression. Isolating cell populations expressing CD34 protein made little difference to gene expression, however, knockdown of the CD34 gene led to decreased expression of progenitor genes. C-MSC increased viability of injured corneal epithelial cells whilst decreasing levels of cytotoxicity and interleukins-6 and -8. No pro-angiogenic effect of C-MSC was seen. Culture medium can significantly influence C-MSC phenotype and culture in SCM produced a cell phenotype more suitable for further consideration as an anti-inflammatory cell therapy. C-MSC show considerable potential for development as therapies for OSIDs, acting through anti-inflammatory action.

High Expression of THY1 in Intestinal Gastric Cancer as a Key Factor in Tumor Biology: A Poor Prognosis-Independent Marker Related to the Epithelial-Mesenchymal Transition Profile.

Gastric cancer (GC) is an important cancer-related death worldwide. Among its histological subtypes, intestinal gastric cancer (IGC) is the most common. A previous work showed that increased expression of the THY1 gene was associated with poor overall survival in IGC. Furthermore, it was shown that IGC tumor cells with high expression of THY1 have a greater capacity for tumorigenesis and metastasis in vitro. This study aimed to identify molecular differences between IGC with high and low expression of THY1. Using a feature selection method, a group of 35 genes were found to be the most informative gene set for THY1high IGC tumors. Through a classification model, these genes differentiate THY1high from THY1low tumors with 100% of accuracy both in the test subset and the independent test set. Additionally, this group of 35 genes correctly clustered 100% of the samples. An extensive validation of this potential molecular signature in multiple cohorts successfully segregated between THY1high and THY1low IGC tumors (>95%), proving to be independent of the gene expression quantification methodology. These genes are involved in central processes to tumor biology, such as the epithelial-mesenchymal transition (EMT) and remodeling of the tumor tissue composition. Moreover, patients with THY1high IGC demonstrated poor survival and a more advanced clinicopathological staging. Our findings revealed a molecular signature for IGC with high THY1 expression. This signature showed EMT and remodeling of the tumor tissue composition potentially related to the biology of IGC. Altogether, our results indicate that THY1high IGC tumors are a particular subset of tumors with a specific molecular and prognosis profile.

TMIC-44. THY1 CONFERS PROLIFERATIVE ADVANTAGES AND THERAPY RESISTANCE WITHIN LOCALIZED NICHES OF GLIOMA

Abstract Resistance to therapy is a hallmark of Glioblastoma (GBM), making it a deadly disease. Earlier, using a longitudinal mouse model, we reported that the immunoglobulin-like cell surface receptor THY1, was significantly upregulated in recurrent GBM tumors. Here, we used single cell and spatial transcriptomics data to track THY1 expression through treatment resistance. Single cell analysis of primary and recurrent GBM shows that THY1 expression is significantly associated with multiple tumor cell states, namely, the NPC-like (Neuronal precursor-like), OPC-like (oligodendrocyte precursor-like) and MES-like (mesenchymal-like) cellular states. Further, spatial analysis of primary GBM shows that tumor cells resident in highly vascularized regions and at invasive edges express significantly high levels of THY1. Specifically, high THY1 levels at the invasive edge is associated with NPC-like state, known to migrate through white matter tracts in vascular regions. In contrast, THY1 expression is high in MES-like cells within recurrent GBM tumor cells. Single cell analysis of a matched primary and recurrent tissue shows a remarkable increase in THY1 expression upon recurrence coincident with a switch to predominantly MES-like state. Using protein markers that define different cellular states we performed immunofluorescence analyses to track the expression of THY1 across both primary and recurrent tumors. We show evidence of high THY1 protein expression associated with NPC-like cells in different niches within primary tumors. In recurrent GBM tissues, THY1 protein expression is significantly higher and present along the palisading regions surrounding necrosis. Finally, we show that dox inducible knockout of THY1 completely abrogates the ability of a patient derived organoid to establish tumors in mice. We are currently exploring this model to study the role of THY1 in therapy resistance. Together, these data suggest that THY1 is critical for tumor growth and upon therapeutic stress can contribute towards shift in tumor cell identity to generate therapy-resistant clonal populations.

Abstract 15697: Exposure to Serum From Exclusive Heated Tobacco Product Smokers Induces mTOR Activation and Fibrotic Features in Human Cardiac Fibroblasts

Introduction: Smokers are at higher risk of fibrosis-related atrial fibrillation. The use of heated tobacco products (HTPs) is rising worldwide with unclear effects on health. The SUR-VAPES chronic trial showed that exclusive HTP smokers have increased serum markers of oxidative/endothelial stress versus non-smokers (NS), comparable to cigarette smokers. Hypothesis: We hypothesized that the serological profile of HTP smokers can activate atrial fibroblasts towards a pro-fibrotic phenotype. Methods: CFs were isolated from discarded atrial tissue from elective cardiac surgery procedures, and exposed to serum lots (20 healthy young subjects each) from HTP smokers (mean exclusive use=1.5 years) or clinically matched NSs from the SUR-VAPES Chronic trial. ANOVA testing was applied. Results: CFs treated with HTP serum increased expression of fibrotic genes, including PDGFA (1.18-fold, p<0.01) and THY1 (1.22-fold, p<0.01), and increased aSMA protein levels (1.87-fold, p<0.01), compared to NS serum. Connexin 43 was downregulated at both mRNA (1.17-fold, p<0.05) and protein levels (1.56-fold, p<0.01) in CFs after exposure to HTP serum versus NS. COL1A1 expression increased (1.46-fold, p<0.01), with higher soluble collagen release (1.56-fold, p<0.05). CFs pre-treated with HTP serum released lower levels of cardioprotective proteins (e.g. Adiponectin, Chi3L1, VEGF) by protein arrays/ELISA (p<0.05 vs NS). Paracrine support of CF-conditioned media to endothelial tube formation (63.3±4.7 vs 37.3±5.7 mesh #/well, p<0.05) and to cardiomyocyte viability under starvation (0.60±0.04 vs 0.47±0.01 normOD vs t0, p<0.001) were reduced when pre-treated with HTP versus NS serum. Array screening of 37 phospho-proteins in CFs exposed to HTP serum for 1h found several beneficial pathways blunted, with many inhibiting mTOR, including decreased P-PRAS40 (-2.43-fold) and P-p53 (-2.32-fold, p<0.05). Western blot analysis on CFs after 48h of HTP serum treatment confirmed increased P-mTOR (1.40-fold), and its targets P-S6K (1.39-fold) and P-4EBP1 (1.83-fold, all p<0.05). Conclusions: The serological profile of chronic exclusive HTP smokers induces CF activation and fibrotic features pointing to a potential risk for atrial fibrosis.

Thy-1 knockdown promotes the osteogenic differentiation of GMSCs via the Wnt/β-catenin pathway.

Gingival mesenchymal stem cells (GMSCs) are newly developed seed cells for tissue engineering owing to their easy isolation, abundance and high growth rates. Thy-1 is an important regulatory molecule in the differentiation of mesenchymal stem cells (MSCs). In this study, we investigated the function of Thy-1 in the osteogenic differentiation of GMSCs by reducing the expression of Thy-1 using a lentivirus. The results demonstrated that Thy-1 knockdown promoted the osteogenic differentiation of GMSCs in vitro. Validation by RNA-seq revealed an obvious decrease in Vcam1 and Sox9 gene expression with Thy-1 knockdown. Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that the differentially expressed genes were enriched in the Wnt signalling pathway. We further demonstrated that Thy-1 knockdown promoted osteogenic differentiation of GMSCs by activating the Wnt/β-catenin signalling pathway. Therefore, Thy-1 has a key regulatory role in the differentiation of GMSCs and maybe a core molecule connecting transcription factors related to the differentiation of MSCs. Our study also highlighted the potential of Thy-1 to modify MSCs, which may help improve their use in tissue engineering.

Autologous Platelet Lysate Is an Alternative to Fetal Bovine Serum for Canine Adipose-Derived Mesenchymal Stem Cell Culture and Differentiation.

The use of fetal bovine serum (FBS) in regenerative medicine raises serious ethical and scientific concerns. We have cultured and differentiated the canine mesenchymal stem cells (cMSCs) in five different media combinations of autologous platelet lysate (A-PL) and FBS; consisting of 0% A-PL and 10% FBS (M-1), 2.5% A-PL and 7.5% FBS (M-2), 5% A-PL and 5% FBS (M-3), 7.5% A-PL and 2.5% FBS (M-4), and 10% A-PL and 0% FBS (M-5). The cMSCs were evaluated for their doubling time, differentiation efficiency, and expression of CD73, CD90, CD105, and PDGFRα. The mRNA expression of NT5E, THY1, ENG, PPARγ, FABP4, FAS, SP7, BGLAP, and SPP1 was also assessed. The results indicated non-significant differences in cellular proliferation/viability; positive expression of surface markers, and PDGFRα with substantial adipo/osteogenic differentiation. The expression of adipogenic (PPARγ, FABP4, FAS), and osteogenic (SP7, BGLAP, SPP1) genes were higher (p < 0.05) in the M5 group. In conclusion, A-PL in cMSCs culture did not negatively affect cellular proliferation and viability but also enhanced their genetic potential for multilineage differentiation. Our results indicate that A-PL can be used as an alternative for FBS to develop potent cMSCs under good manufacturing practice protocol for regenerative medicine.

SIX1 Downregulation Suppresses Self-renewal Capacity and THY1 Expression in Hepatocellular Carcinoma and SIX1 Dominate the Survival in Liver Cancer.

Sine oculis homeoprotein 1 exerts an essential role in embryonic development, and it was also identified to be reactivated in various types of mammalian cancer. The sine oculis homeoprotein 1 transcription factor was demonstrated to induce epithelial-mesenchymal transition, regulate crucial genes associated with cancer progression, and increase the oncogenic potential of cells. Therefore, the present study aimed to identify the role of sine oculis homeoprotein 1 in cancer. Sine oculis homeoprotein 1 gene expression was tested with real-time quantitative polymerase chain reaction (PCR) in different cancer types. Sine oculis homeoprotein 1 expression was suppressed by short hairpin RNA transduction in the SNU398 hepatocellular carcinoma cell line. The effects of sine oculis homeoprotein 1 on cell proliferation, drug resistance, and sphere formation were assessed in shSIX1 cells. Immunohistochemical and in silico analyses were performed to determine the prognostic role of sine oculis homeoprotein 1 expression. The upregulated expression levels of sine oculis homeoprotein 1 were revealed to be correlated with the stage of the disease in breast, colon, and liver cancer, with liver cancer exhibiting the highest expression profile. Sine oculis homeoprotein 1 downregulation significantly affected cell proliferation and suppressed sorafenib resistance and sphere-forming ability. Furthermore, sine oculis homeoprotein 1 knockdown cells were identified to have decreased CD90 levels, essential for cancer stem cell properties. Finally, sine oculis homeoprotein 1 expression was a CD90-independent biomarker for the clinical prognosis of liver cancer. The results of this study showed that the knockdown of sine oculis homeoprotein 1 expression might help to prevent hepatocarcinogenesis by increasing drug sensitivity and controlling tumor sphere formation. Overall, these results indicated that sine oculis homeoprotein 1 expression might be useful as a diagnostic marker for patients with hepatocellular carcinoma.

Purification of retinal ganglion cells using low-pressure flow cytometry.

Purified Retinal Ganglion Cells (RGCs) for in vitro study have been a valuable tool in the study of neural regeneration and in the development of therapies to treat glaucoma. Traditionally, RGCs have been isolated from early postnatal rats and mice, and more recently from human in vitro derived retinal organoids using a two-step immunopanning technique based upon the expression of Thy-1. This technique, however, limits the time periods from which RGCs can be isolated, missing the earliest born RGCs at which time the greatest stage of axon growth occurs, as well as being limited in its use with models of retinal degeneration as Thy-1 is downregulated following injury. While fluorescence associated cell sorting (FACS) in combination with new optogenetically labeled RGCs would be able to overcome this limitation, the use of traditional FACS sorters has been limited to genomic and proteomic studies, as RGCs have little to no survival post-sorting. Here we describe a new method for RGC isolation utilizing a combined immunopanning-fluorescence associated cell sorting (IP-FACS) protocol that initially depletes macrophages and photoreceptors, using immunopanning to enrich for RGCs before using low-pressure FACS to isolate these cells. We demonstrate that RGCs isolated via IP-FACS when compared to RGCs isolated via immunopanning at the same age have similar purity as measured by antibody staining and qRT-PCR; survival as measured by live dead staining; neurite outgrowth; and electrophysiological properties as measured by calcium release response to glutamate. Finally, we demonstrate the ability to isolate RGCs from early embryonic mice prior to the expression of Thy-1 using Brn3b-eGFP optogenetically labeled cells. This method provides a new approach for the isolation of RGCs for the study of early developed RGCs, the study of RGC subtypes and the isolation of RGCs for cell transplantation studies.

Identifying immune cell infiltration and diagnostic biomarkers in heart failure and osteoarthritis by bioinformatics analysis.

Heart failure (HF) and osteoarthritis (OA) are medical conditions that can significantly impact daily activities. Evidence has shown that HF and OA may share some pathogenic mechanisms. However, the underlying genomic mechanisms remain unclear. This study aimed to explore the underlying molecular mechanism and identify diagnostic biomarkers for HF and OA. With the cutoff criteria of fold change (FC) > 1.3 and P < .05, 920, 1500, 2195, and 2164 differentially expressed genes (DEGs) were identified in GSE57338, GSE116250, GSE114007, and GSE169077, respectively. After making the intersection of DEGs, we obtained 90 upregulated DEGs and 51 downregulated DEGs in HF datasets and 115 upregulated DEGs and 75 downregulated DEGs in OA datasets. Afterward, we conducted genome ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, protein-protein interaction (PPI) networks, and hub genes screening based on DEGs. Then, 4 common DEGs (fibroblast activation protein alpha [FAP], secreted frizzled-related protein 4 (SFRP4), Thy-1 cell surface antigen (THY1), matrix remodeling associated 5 [MXRA5]) between HF and OA were screened and validated in GSE5406 and GSE113825 datasets, based on which we established the support vector machine (SVM) models. The combined area under the receiver operating characteristic curve (AUC) of THY1, FAP, SFRP4, and MXRA5 in the HF training and test sets reached 0.949 and 0.928. While in the OA training set and test set, the combined AUC of THY1, FAP, SFRP4, and MXRA5 reached 1 and 1, respectively. The analysis of immune cells in HF revealed high levels of dendritic cell (DC), B cells, natural killer T cell (NKT), Type 1 regulatory T cell (Tr1), cytotoxic T cell (Tc), exhausted T cell (Tex), and mucosal-associated invariant T cell (MAIT), while displaying lower levels of monocytes, macrophages, NK, CD4 + T, gamma delta T (γδ T), T helper type 1 (Th1), T helper type 2 (Th2), and effector memory T cell (Tem). Moreover, the 4 common DEGs were positively correlated with DCs and B cells and negatively correlated with γδ T. In OA patients, the abundance of monocyte, macrophage, CD4 + naïve, and natural T regulatory cell (nTreg) was higher, while the infiltration of CD8 + T, γδ T, CD8 + naïve, and MAIT was lower. The expression of THY1 and FAP was significantly correlated with macrophage, CD8 + T, nTreg, and CD8 + naïve. SFRP4 was correlated with monocyte, CD8 + T, γδ T, CD4 + naïve, nTreg, CD8 + naïve and MAIT. MXRA5 was correlated with macrophage, CD8 + T, nTreg and CD8 + naïve. FAP, THY1, MXRA5, and SFRP4 may be diagnostic biomarkers for both HF and OA, and their correlation with immune cell infiltrations suggests shared immune pathogenesis.

Low Magnesium Concentration Enforces Bone Calcium Deposition Irrespective of 1,25-Dihydroxyvitamin D3 Concentration.

Efficient coordination between Mg2+ and vitamin D maintains adequate Ca2+ levels during lactation. This study explored the possible interaction between Mg2+ (0.3, 0.8, and 3 mM) and 1,25-dihydroxyvitamin D3 (1,25D; 0.05 and 5 nM) during osteogenesis using bovine mesenchymal stem cells. After 21 days, differentiated osteocytes were subjected to OsteoImage analysis, alkaline phosphatase (ALP) activity measurements, and immunocytochemistry of NT5E, ENG (endoglin), SP7 (osterix), SPP1 (osteopontin), and the BGLAP gene product osteocalcin. The mRNA expression of NT5E, THY1, ENG, SP7, BGLAP, CYP24A1, VDR, SLC41A1, SLC41A2, SLC41A3, TRPM6, TRPM7, and NIPA1 was also assessed. Reducing the Mg2+ concentration in the medium increased the accumulation of mineral hydroxyapatite and ALP activity. There was no change in the immunocytochemical localization of stem cell markers. Expression of CYP24A1 was higher in all groups receiving 5 nM 1,25D. There were tendencies for higher mRNA abundance of THY1, BGLAP, and NIPA1 in cells receiving 0.3 mM Mg2+ and 5 nM 1,25D. In conclusion, low levels of Mg2+ greatly enhanced the deposition of bone hydroxyapatite matrix. The effect of Mg2+ was not modulated by 1,25D, although the expression of certain genes (including BGLAP) tended to be increased by the combination of low Mg2+ and high 1,25D concentrations.

THY1 (CD90) Maintains the Adherens Junctions in Nasopharyngeal Carcinoma via Inhibition of SRC Activation

We had previously shown that THY1 (CD90) is a tumor suppressor in nasopharyngeal carcinoma (NPC) and that its down-regulation and loss of expression are associated with tumor metastasis, yet the mechanism leading to such effects remains unknown. In this study we show that tumor invasion could be suppressed by THY1 via adherens junction formation in a few NPC cell lines, and knockdown of THY1 would disrupt this cell-cell adhesion phenotype. Mechanistically, the activity of the SRC family kinase (SFK) member, SRC, and canonical Wnt signaling were dramatically reduced when THY1 was constitutively expressed. Previous studies by others have found that high levels of SRC activity in NPCs are associated with EMT and a poor prognosis. We hypothesized that THY1 can suppress tumor invasion in NPC via inhibition of SRC. By gene silencing of SRC, we found that the in vitro NPC cell invasion was significantly reduced and adherens junctions were restored. Through proteomic analysis, we identified that platelet-derived growth factor receptor β (PDGF-Rβ) and protein tyrosine phosphatase nonreceptor type 22 (PTPN22) are novel and potential binding partners of THY1, which were subsequently verified by co-immunoprecipitation (co-IP) analysis. The ligand of PDGF-Rβ (PDGF-BB) could highly induce SRC activation and NPC cell invasion, which could be almost completely suppressed by THY1 expression. On the other hand, the PTPN22 siRNA could enhance both the SRC activities and the cell invasion and could also disrupt the adherens junctions in the THY1-expressing NPC cells; the original THY1-induced phenotypes were reverted when the PTPN22 expression was reduced. Together, our results identified that PTPN22 is essential for THY1 to suppress cell invasion and SRC activity, maintain tight adherens junctions, and prevent NPC metastasis. These results suggested that PDGF-Rβ and SRC can be used as drug targets for suppressing NPC metastasis. Indeed, our in vivo assay using the SRC inhibitor KX2-391, clearly showed that inhibition of SRC signaling can prevent the metastasis of NPC, indicating that targeting SRC can be a promising approach to control the NPC progression.

Abstract 3909: THY1 regulates therapy resistance in glioblastoma recurrence

Abstract Glioblastoma (GBM), is the most common primary brain tumor. It is a lethal disease with a median survival of 15 months characterized by treatment resistance, aggressive brain invasion, and inevitable recurrence. Less than 10 percent of patients survive beyond 5 years. Here, we developed an intracranial longitudinal in vivo recurrence model using HF2303, a patient derived explant, to produce paired specimens (pre- and post-recurrence) following temozolomide(TMZ) and radiation(IR) treatment. Mouse brain tissues from the two groups were compared to identify genes and pathways driving treatment resistance. This analysis showed an elevated THY1 expression in recurrent HF2303 tumors compared to naïve tumors. Increased Thy1 expression was also associated with a more mesenchymal phenotype. THY1 expressing cells from naïve HF2303 were also resistant to TMZ/IR treatment in an intracranial model. In U87 neurospheres, overexpression of THY1 increased resistance to TMZ/IR. Interestingly, stable knockdown of Thy1 in GBM cells and human derived GBM organoids (GBOs) expressing high THY1 levels led to reduced cell proliferation. Yet, an inducible knockout of THY1 using CRISPR/Cas9 in human GBOs showed increased sensitivity to TMZ/IR. This suggests a clear link between THY1 expression and TMZ/IR resistance.Single cell RNA sequencing of over 25 primary GBM and 4 recurrent tumors (spanning over 120,000 cells) shows that cells expressing high levels of THY1 are associated with two distinct populations; neuronal precursor-like (NPC-like) and mesenchymal-like (MES-like). Furthermore spatial transcriptomics from 3 primary GBMs suggests that high THY1 expressing cells are colocalized with macrophages within the perivascular niche contributing to the mesenchymal phenotype. We will present these studies and our more recent work analyzing spatial recurrent GBM samples. Particularly, we will address how THY1 expression in these spatially distinct NPC-like and MES-like differ and how each of these states may contribute towards TMZ/IR resistance. Citation Format: Sunita Shankar, Visweswaran Ravikumar, Hanxiao Wang, Sunjong Ji, Zainab Hasan, Ziad Fehmi, Yacoub Haydin, Daniel R. Wahl, Arvind Rao, Alnawaz Rehemtulla, Wajd Al-Holou. THY1 regulates therapy resistance in glioblastoma recurrence. [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 3909.

Identification of biomarkers of hepatocellular carcinoma gene prognosis based on the immune-related lncRNA signature of transcriptome data

Long non-coding RNAs (lncRNAs) are well established to have an important role in cancer. The goal of this research was to investigate the prognostic usefulness of putative immune-related lncRNAs in hepatocellular carcinoma (HCC). The developed lncRNA signature was validated using 343 HCC patients from The Cancer Genome Atlas (TCGA) and 81 samples from Gene Expression Omnibus (GEO). Cox regression and Least Absolute Shrinkage and Selection Operator (LASSO) analysis were used to analyze immune-related lncRNAs for HCC prognosis. Patients in the low-risk group survived substantially longer than those in the high-risk group (P < 0.05). The discovered signal might be a useful prognostic factor for predicting patient survival. Overall survival predicted some clinical net improvements, according to the nomogram. Numerous enrichment approaches (including gene set enrichment analysis) were utilized to investigate the underlying mechanisms. Drug metabolism, mTOR, and p53 signaling pathways were associated with high-risk groups. When the expression of lncRNA PRRT3-AS1 was silenced in HepG2 cells, the proliferation, migration, and invasion abilities of HepG2 cells were decreased, and apoptosis was enhanced. In the supernatant from HepG2 cells with PRRT3-AS1 knockdown, the anti-inflammatory factors IL-10 and TGF-1 were induced, whereas the pro-inflammatory factors IL-1β, TNF-α, and IL-6 were reduced (P < 0.05). After PRRT3-AS1 knockdown, the protein expression of CD24, THY1, LYN, CD47, and TRAF2 in HepG2 cells was attenuated (P < 0.05). The discovery of five immune-related lncRNA signatures has significant therapeutic significance for predicting patient prognosis and directing personalized treatment for patients with HCC, which requires additional prospective confirmation.