Beta-galactosidase Activity Research Articles

Abstract A29: Anticancer effects of polo-like kinase-4 inhibitor (CFI-400945) in ovarian cancer

Abstract Background: Dysregulation of cell cycle and mitosis plays a pivotal role in carcinogenesis. Polo-like kinase (PLK) regulates centriole duplication and mitosis and is crucial in maintaining the genomic stability in cancer cells. Disruption of this process may affect cancer cell growth and so PLK represents a druggable target in cancer therapy. CFI-400945 is a small molecule against PLK4 activity, and this study aims to investigate its anticancer efficacy and mechanisms in ovarian cancer cells. Methods: Expression of PLK4 in ovarian cancer patients was determined by Taqman quantitative PCR (qPCR) at transcriptional level. To assess the in vitro growth inhibition effect of CFI-400945, XTT cell viability assay was employed to compare the IC50 of CFI-400945 in a panel of 25 ovarian cancer cell lines of different histologic origins, and the antiproliferative results were assessed by direct cell counting assay. The anticancer activity of CFI-400945 in ovarian cancer cells were further studied by (1) propidium iodide (PI) staining to assess its impact on cell cycle and cell division, (2) annexin V staining to determine the level of apoptosis, (3) gH2AX Western blotting and gH2AX/RAD51 co-immunofluorescence to reveal its effect on DNA damage and repair, and (4) beta-galactosidase activity staining to study the outcome of senescence induced by CFI-400945. To study the change of gene expression induced by CFI-400945 at molecular level, poly-A capture RNA sequencing (RNAseq) was performed in OCC1 and ES2. Results: The qPCR assay significantly demonstrated overexpression of PLK4 in ovarian cancer tumor tissue when compared to nontumor. The growth inhibition effect of CFI-400945 varied among different ovarian cancer cell lines, with IC50 ranging from 0.7 to 68.2nmol. PI-based cell cycle analysis clearly demonstrated the presence of aneuploidy up to 16N, indicating the failure of cell division after S phase DNA duplication. In addition to its impact on cell division, gH2AX immunofluorescent staining and Western blotting also revealed CFI-400945 induced DNA damage. However, induction of apoptosis was only rarely seen in the cell lines tested. The aneuploidy formation and low level of apoptosis was followed by cellular senescence, which was evidenced by 3-fold increase in the number of cells having positive beta-galactosidase staining after CFI-400945 treatment as compared to control. RNAseq of OCC1 and ES2 showed an induction of senescence-associated secretory phenotypes, like IL6 and P21, and suppression of DNA repair gene expression, like RAD51 and BRCA1, which were in agreement with our in vitro observation. Conclusion: CFI-400945 had antiproliferative effect in ovarian cancer cell lines of different histologic origins, and its anticancer activity was attributable to DNA damage, its suppressive effect on DNA repair, failure of cell division, and subsequent cell senescence. Further study would focus on enhancing the anticancer activity of CFI-400945 through drug combination against DNA damage repair. Citation Format: Ka Yu Tse, Kin Tak Chan, Vincent Yuen, Misty Shuo Zhang, Philip Pun Ching Ip, Hextan Yeung Sheung Ngan, Mark Bray, Carmen Chai Lui Wong, Tak Wah Mak. Anticancer effects of polo-like kinase-4 inhibitor (CFI-400945) in ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A29.

Cancer Stem Cell-Inducing Media Activates Senescence Reprogramming in Fibroblasts.

Cellular senescence is a tumor-suppressive mechanism blocking cell proliferation in response to stress. However, recent evidence suggests that senescent tumor cells can re-enter the cell cycle to become cancer stem cells, leading to relapse after cancer chemotherapy treatment. Understanding how the senescence reprogramming process is a precursor to cancer stem cell formation is of great medical importance. To study the interplay between senescence, stemness, and cancer, we applied a stem cell medium (SCM) to human embryonic fibroblasts (MRC5 and WI-38) and cancer cell lines (A549 and 293T). MRC5 and WI-38 cells treated with SCM showed symptoms of oxidative stress and became senescent. Transcriptome analysis over a time course of SCM-induced senescence, revealed a developmental process overlapping with the upregulation of genes for growth arrest and the senescence-associated secretory phenotype (SASP). We demonstrate that histone demethylases jumonji domain-containing protein D3 (Jmjd3) and ubiquitously transcribed tetratricopeptide repeat, X chromosome (Utx), which operate by remodeling chromatin structure, are implicated in the senescence reprogramming process to block stem cell formation in fibroblasts. In contrast, A549 and 293T cells cultured in SCM were converted to cancer stem cells that displayed the phenotype of senescence uncoupled from growth arrest. The direct overexpression of DNA methyltransferases (Dnmt1 and Dnmt3A), ten-eleven translocation methylcytosine dioxygenases (Tet1 and Tet3), Jmjd3, and Utx proteins could activate senescence-associated beta-galactosidase (SA-β-gal) activity in 293T cells, suggesting that epigenetic alteration and chromatin remodeling factors trigger the senescence response. Overall, our study suggests that chromatin machinery controlling senescence reprogramming is significant in cancer stem cell formation.

Persistent DNA Damage and Senescence in the Placenta Impacts Developmental Outcomes of Embryos.

Cohesin is an evolutionarily conserved chromosome-associated protein complex essential for chromosome segregation, gene expression, and repair of DNA damage. Mutations that affect this complex cause the human developmental disorder Cornelia de Lange syndrome (CdLS), thought to arise from defective embryonic transcription. We establish a significant role for placental defects in the development of CdLS mouse embryos (Nipbl and Hdac8). Placenta is a naturally senescent tissue; we demonstrate that persistent DNA damage potentiates senescence and activates cytokine signaling. Mutant embryo developmental outcomes are significantly improved in the context of a wild-type placenta or by genetically restricting cytokine signaling. Our study highlights that cohesin is required for maintaining ploidy and the repair of spontaneous DNA damage in placental cells, suggesting that genotoxic stress and ensuing placental senescence and cytokine production could represent a broad theme in embryo health and viability.

Xela DS2 and Xela VS2: Two novel skin epithelial-like cell lines from adult African clawed frog (Xenopus laevis) and their response to an extracellular viral dsRNA analogue

The skin epithelial layer acts as an important immunological barrier against pathogens and is capable of recognizing and responding to pathogen-associated molecular patterns (PAMPs) in human and mouse models. Although presumed, it is unknown whether amphibian skin epithelial cells exhibit the ability to respond to PAMPs such as viral double-stranded RNA (dsRNA). To address this, two cell lines from the dorsal skin (Xela DS2) and ventral skin (Xela VS2) of the African clawed frog (Xenopus laevis) were established. Xela DS2 and Xela VS2 cells have an epithelial-like morphology, express genes associated with epithelial cells, and lack senescence-associated beta-galactosidase activity. Cells grow optimally in 70% Leibovitz's L-15 medium supplemented with 15% fetal bovine serum at 26 °C. Upon treatment with poly(I:C), a synthetic analogue of viral dsRNA and known type I interferon inducer, Xela DS2 and Xela VS2 exhibit marked upregulation of key antiviral and pro-inflammatory transcripts suggesting frog epithelial cells participate in the recognition of extracellular viral dsRNA and production of local inflammatory signals; similar to human and mouse models. Currently, these are the only known Xenopus laevis skin epithelial-like cell lines and will be important for future research in amphibian epithelial cell biology, initial host-pathogen interactions, and rapid screening of the effects of environmental stressors, including contaminants, on frog skin epithelial cells.

465-P: Thrombin Induces SGLT1 and SGLT2 Expression to Promote the AT1R/NADPH Oxidase-Mediated Pro-oxidant Response Inducing Senescence in Atrial Endothelial Cells

Selective sodium-glucose cotransporter 2 (SGLT2) inhibitors have shown cardiovascular protection in type 2 diabetes patients with established cardiovascular (CV) disease independently of glycemic control. Although blood-derived coagulation factors are major contributors of CV diseases, their impact on the expression of SGLT1 and 2 in endothelial cells (ECs) has not been studied. This study investigated whether thrombin affects the expression of SGLT1 and 2 and examined their role in the induction of endothelial senescence. ECs were isolated from porcine atrial tissue (AECs) and used at first passage. Endothelial senescence was assessed by determining senescence-associated beta-galactosidase (SA-beta-gal) activity, oxidative stress using dihydroethidium, and protein level by Western blot analysis and immunofluorescence staining. Exposure of AECs to thrombin (1 or 3 U/ml) for 24 h induced an upregulation of the low protein expression level of SGLT1 and SGLT2. Thrombin induced a sustained pro-oxidant response and increased the level of SA-beta-gal activity that were both inhibited by antioxidants, an angiotensin-converting enzyme inhibitor and an AT1 receptor antagonist and also by sotagliflozin (a dual SGLT1 and SGLT2 inhibitor) and by empagliflozin (a selective SGLT2 inhibitor). In addition, thrombin upregulated the expression level of angiotensin-converting enzyme and AT1 receptors, VCAM-1 and down-regulated that of endothelial NO synthase. In conclusion, thrombin up-regulates both SGLT1 and SGLT2 expression in AECs to sustain oxidative stress leading to endothelial senescence and dysfunction. The fact that the AT1R/NADPH oxidase/SGLT1 and 2 pathway acts in a feedforward manner suggests that inhibition of SGLT1 and/or SGLT2 appears as an attractive strategy to perpetuate the protective endothelial function on the cardiovascular system. Disclosure H. Hasan: None. S. Park: None. E. Belcastro: None. C. Auger: None. H. Lee: None. V. Schini-Kerth: Research Support; Self; Boehringer Ingelheim International GmbH.

Reduction of senescence-associated beta-galactosidase activity by vitamin E in human fibroblasts depends on subjects' age and cell passage number.

Cell senescence is due to the permanent cell cycle arrest that occurs as a result of the inherent limited replicative capacity toward the Hayflick limit (replicative senescence), or in response to various stressors (stress-induced premature senescence, SIPS). With the acquisition of the senescence-associated secretory phenotype (SASP), cells release several molecules (cytokines, proteases, lipids), and express the senescence-associated beta-galactosidase (SA-β-Gal). Here we tested whether vitamin E affects SA-β-Gal in an in vitro model of cell ageing. Skin fibroblasts from human subjects of different age (1, 13, 29, 59, and 88 years old) were cultured until they reached replicative senescence. At different passages (Passages 2, 9, 13, and 16), these cells were treated with vitamin E for 24 hr. Vitamin E reduced SA-β-Gal in all cells at passage 16, but at earlier passage numbers it reduced SA-β-Gal only in cells isolated from the oldest subjects. Therefore, short time treatment with vitamin E decreases SA-β-Gal in cells both from young and old subjects when reaching replicative senescence; but in cells isolated from older subjects, a decrease in SA-β-Gal by vitamin E occurs also at earlier passage numbers. The possible role of downregulation of CD36 by vitamin E, a scavenger receptor essential for initiation of senescence and SASP, is discussed.

Effects of Metformin on Life Span, Cognitive Ability, and Inflammatory Response in a Short-Lived Fish.

Metformin, an oral antidiabetic drug, prolongs the life span in nematode, silkworm, and other transgenic rodents, but its effects on longevity and aging-related cognitive ability using natural aging vertebrate models remain poorly understood. The genus of annual fish Nothobranchius show accelerated growth and expression of aging biomarkers. Here, using the short-lived fish Nothobranchius guentheri, we investigated effects of metformin on life span and aging-related cognitive ability and inflammation. Total of 145 fish, 72 fish were fed with metformin in the concentration of 2 mg/g food and 73 fish without metformin from 16 weeks of age until the end of their lives. The chronic feeding with metformin prolonged the life span of the fish and delayed aging with retarded accumulation of lipofuscin in liver, senescence-associated beta-galactosidase (SA-β-gal) activity in skin and serum levels of cholesterol and triglyceride significantly in the 10-month-old fish. Furthermore, metformin improved motor, learning, and memory skills by behavior tests accompanying with reduction of SA-β-gal activity and neurofibrillary degeneration and inhibition of inflammatory response including downregulated NF-κB and proinflammatory cytokines IL-8, TNF-α, and IL-1β expression and enhanced anti-inflammatory cytokine IL-10 level in brain. These findings demonstrate that metformin prolongs the life span and exerts neuroprotective and anti-inflammation function to improve cognitive ability in annual fish. It might be an effective strategy by using metformin to raise the possibility of promoting healthy aging of old population in aging process.

A20 of nucleus pulposus cells plays a self-protection role via the nuclear factor-kappa B pathway in the inflammatory microenvironment.

AimsInflammatory response plays a pivotal role in the pathophysiological process of intervertebral disc degeneration (IDD). A20 (also known as tumour necrosis factor alpha-induced protein 3 (TNFAIP3)) is a ubiquitin-editing enzyme that restricts nuclear factor-kappa B (NF-κB) signalling. A20 prevents the occurrence of multiple inflammatory diseases. However, the role of A20 in the initiation of IDD has not been elucidated. The aim of the study was to investigate the effect of A20 in senescence of TNF alpha (TNF-α)-induced nucleus pulposus cells (NPCs).MethodsImmunohistochemical staining was performed to observe the expression of A20 in normal and degenerated human intervertebral discs. The NPCs were dissected from the tail vertebrae of healthy male Sprague-Dawley rats and were cultured in the incubator. In the experiment, TNF-α was used to mimic the inflammatory environment of IDD. The cell viability and senescence were examined to investigate the effect of A20 on TNF-α-treated NPCs. The expression of messenger RNA (mRNA)-encoding proteins related to matrix macromolecules (collagen II, aggrecan) and senescence markers (p53, p16). Additionally, NF-κB/p65 activity of NPCs was detected within different test compounds.ResultsThe expression of A20 was upregulated in degenerate human intervertebral discs. The A20 levels of NPCs in TNF-α inflammatory microenvironments were dramatically higher than those of the control group. TNF-α significantly decreased cell proliferation potency but increased senescence-associated beta-galactosidase (SA-β-Gal) activity, the expression of senescence-associated proteins, the synthesis of extracellular matrix, and G1 cycle arrest. The senescence indicators and NF-κB/p65 expression of A20 downregulated group treated with TNF-α were significantly upregulated compared to TNF-α-treated normal NPCs.ConclusionA20 has a self-protective effect on the senescence of NPCs induced by TNF-α. The downregulation of A20 in NPCs exacerbated the senescence of NPCs induced by TNF-α.Cite this article: Bone Joint Res. 2020;9(5):225–235.

Twist1 regulates cellular senescence in mesenchymal stem cells

Purpose: Mesenchymal stem cells (MSCs) are promising cells to treat skeletal related diseases such as osteoarthritis (OA). One of the limitations that reduces the therapeutic use of MSCs for OA cell-based treatments is cellular senescence. Cellular senescence is a state of the cell in which cells stop proliferating, while still be metabolically active. By acquiring a specific senescence-associated secretory phenotype (SASP), senescent MSCs can contribute to cartilage degeneration and chronic inflammation. The molecular mechanism behind cellular senescence in MSCs remains largely unknown. The transcription factor TWIST1 is suggested to play a role in cellular senescence, since its expression is reduced in slow proliferating MSCs and we previously demonstrated that high TWIST1-expressing MSCs have an enhanced expansion capacity. The aim of this research is therefore to determine the role of TWIST1 in regulating cellular senescence of MSCs. Methods: Human MSCs were obtained from bone chips from leftover iliac crest of patients undergoing cleft palate reconstructive surgery (N=4, 9-13 years). MSCs were expanded in alpha-MEM containing 10% serum and 1 ng/ml FGF2. To determine the effect of TWIST1 silencing on senescence, MSCs were treated with 15 nM TWIST1 siRNA and Lipofectamine RNAMAX Transfection Reagent (siTWIST1). Scramble siRNA and untreated cells were used as controls. To overexpress TWIST1, MSCs were transduced with a third generation TWIST1 overexpression lentiviral construct. Untreated MSCs and MSCs which overexpress GFP or an empty vector were used as control. The transduction efficiency, of GFP-positive MSCs, was determined using fluorescent microscopy. To determine cellular senescence, we determined senescence-associated beta-galactosidase (SA-β-gal) activity and quantified negative, low and high positive cells. In addition gene expression for IL8, IL6, IL1B, P21 and P16 were analyzed to assess cellular senescence in MSCs. Gene expression was normalized using the best housekeeper index of HPRT, RSP27a and GAPDH. The expansion capacity of the MSCs was determined by cell count. To analyze statistical significance, linear mixed model was applied, the different conditions were considered as fixed parameter and the donors as random parameter. Bonferroni post hoc test was performed to correct for multiple comparisons. Results: TWIST1 transduced MSCs had an average of 151-fold increase in TWIST1 expression detected by RT-PCR, a reduced percentage of SA-B-gal positive cells (71% reduction) and a reduced expression of the SASP related genes IL6 (1.8-fold reduction), IL8 (2.4-fold reduction) and IL1B (1.3-fold reduction) compared to transduction control (Figure 1). In addition, the expansion capacity of MSCs overexpressing TWIST1 was increased, resulting in a 1.5-fold increase in cell number after 4 days. These data indicate that TWIST1 delays cellular senescence in MSCs. Next, we determined the effect of TWIST1 silencing on cellular senescence associated markers. A high percentage of siTWIST1 MSCs were high positive for SA-B-gal (9.5-fold compared to controls, Figure 2A) and cells had a reduced expansion capacity compared to control conditions (20-fold reduction in cell number after 14 days). These data suggest that silencing TWIST1 in MSCs increases cellular senescence. Surprisingly, the expression of SASP related genes IL6 and IL8 was reduced in siTWIST cells compared to untreated control (IL6, 1.6-fold; IL8, 7.2-fold reduction, Figure 2B) and no induction of IL1B was observed in the siTWIST1 MSCs. Low IL6, IL8 and IL1B expression in senescent cells was recently described as mitochondrial dysfunction-associated senescence (MiDAS). We then further analyzed siTWIST1 MSCs for the expression of senescent markers not associated with a SASP phenotype and found that P16 and P21, associated to the cell cycle regulation, were increased after TWIST1 silencing (5.9-fold and 1.6-fold, respectively) in accordance with a senescent phenotype. Overall, these data indicate that TWIST1 silencing results in cellular senescence of MSCs with an uncommon SASP expression. Conclusions: Our Results indicate that TWIST1 plays a role in a special type of cellular senescence, previously described as MiDAS, with a unique SASP expression profile, lacking IL6, IL8 and IL1B upregulation. In addition these data show that different type of senescent cells can have a different SASP expression and therefore potentially have different effects on the microenvironment. Here, we show how TWIST1 may be a target to modulate cellular senescence to improve MSC-based OA therapies.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

SIV Infection and the HIV Proteins Tat and Nef Induce Senescence in Adipose Tissue and Human Adipose Stem Cells, Resulting in Adipocyte Dysfunction.

Background: Aging is characterized by adipose tissue senescence, inflammation, and fibrosis, with trunk fat accumulation. Aging HIV-infected patients have a higher risk of trunk fat accumulation than uninfected individuals—suggesting that viral infection has a role in adipose tissue aging. We previously demonstrated that HIV/SIV infection and the Tat and Nef viral proteins were responsible for adipose tissue fibrosis and impaired adipogenesis. We hypothesized that SIV/HIV infection and viral proteins could induce adipose tissue senescence and thus lead to adipocyte dysfunctions. Methods: Features of tissue senescence were evaluated in subcutaneous and visceral adipose tissues of SIV-infected macaques and in human adipose stem cells (ASCs) exposed to Tat or Nef for up to 30 days. Results: p16 expression and p53 activation were higher in adipose tissue of SIV-infected macaques than in control macaques, indicating adipose tissue senescence. Tat and Nef induced higher senescence in ASCs, characterized by higher levels of senescence-associated beta-galactosidase activity, p16 expression, and p53 activation vs. control cells. Treatment with Tat and Nef also induced oxidative stress and mitochondrial dysfunction. Prevention of oxidative stress (using N-acetyl-cysteine) reduced senescence in ASCs. Adipocytes having differentiated from Nef-treated ASCs displayed alterations in adipogenesis with lower levels of triglyceride accumulation and adipocyte marker expression and secretion, and insulin resistance. Conclusion: HIV/SIV promotes adipose tissue senescence, which in turn may alter adipocyte function and contribute to insulin resistance.

An Optimized Protocol for Histochemical Detection of Senescence-associated Beta-galactosidase Activity in Cryopreserved Liver Tissue

Senescence-associated beta-galactosidase (SA-β-gal) activity assay is commonly used to evaluate the increased beta-galactosidase (β-gal) activity in senescent cells related to enhanced lysosomal activity. Although the optimal pH for β-gal is 4.0, this enzymatic activity has been most commonly investigated at a suboptimal pH by using histochemical reaction on fresh tissue material. In the current study, we optimized a SA-β-gal activity histochemistry protocol that can also be applied on cryopreserved hepatic tissue. This protocol was developed on livers obtained from control rats and after bile duct resection (BDR). A significant increase in β-gal liver activity was observed in BDR rats vs controls after 2 hr of staining at physiological pH 4.0 (6.98 ± 1.19% of stained/total area vs 0.38 ± 0.22; p<0.01) and after overnight staining at pH 5.8 (24.09 ± 6.88 vs 0.12 ± 0.08; p<0.01). Although we noticed that β-gal activity staining decreased with cryopreservation time (from 4 to 12 months of storage at -80C; p<0.05), the enhanced staining observed in BDR compared with controls remained detectable up to 12 months after cryopreservation (p<0.01). In conclusion, we provide an optimized protocol for SA-β-gal activity histochemical detection at physiological pH 4.0 on long-term cryopreserved liver tissue.

Targeted Reduction of Senescent Cell Burden Alleviates Focal Radiotherapy-Related Bone Loss.

Clinical radiotherapy treats life-threatening cancers, but the radiation often affects neighboring normal tissues including bone. Acute effects of ionizing radiation include oxidative stress, DNA damage, and cellular apoptosis. We show in this study that a large proportion of bone marrow cells, osteoblasts, and matrix-embedded osteocytes recover from these insults only to attain a senescent profile. Bone analyses of senescence-associated genes, senescence-associated beta-galactosidase (SA-β-gal) activity, and presence of telomere dysfunction-induced foci (TIF) at 1, 7, 14, 21, and 42 days post-focal radiation treatment (FRT) in C57BL/6 male mice confirmed the development of senescent cells and the senescence-associated secretory phenotype (SASP). Accumulation of senescent cells and SASP markers were correlated with a significant reduction in bone architecture at 42 days post-FRT. To test if senolytic drugs, which clear senescent cells, alleviate FRT-related bone damage, we administered the senolytic agents, dasatinib (D), quercetin (Q), fisetin (F), and a cocktail of D and Q (D+Q). We found moderate alleviation of radiation-induced bone damage with D and Q as stand-alone compounds, but no such improvement was seen with F. However, the senolytic cocktail of D+Q reduced senescent cell burden as assessed by TIF+ osteoblasts and osteocytes, markers of senescence (p16 Ink4a and p21), and key SASP factors, resulting in significant recovery in the bone architecture of radiated femurs. In summary, this study provides proof of concept that senescent cells play a role in radiotherapy-associated bone damage, and that reduction in senescent cell burden by senolytic agents is a potential therapeutic option for alleviating radiotherapy-related bone deterioration. © 2020 American Society for Bone and Mineral Research.

IPSC-Derived MSCs Versus Originating Jaw Periosteal Cells: Comparison of Resulting Phenotype and Stem Cell Potential.

Induced pluripotent stem cell-derived mesenchymal stem cell-like cells (iMSCs) are considered to be a promising source of progenitor cells for approaches in the field of bone regeneration. In a previous study, we described the generation of footprint-free induced pluripotent stem cells (iPSCs) from human jaw periosteal cells (JPCs) by transfection of a self-replicating RNA (srRNA) and subsequent differentiation into functional osteogenic progenitor cells. In order to facilitate the prospective transfer into clinical practice, xeno-free reprogramming and differentiation methods were established. In this study, we compared the properties and stem cell potential of the iMSCs produced from JPC-derived iPSCs with the parental primary JPCs they were generated from. Our results demonstrated, on the one hand, a comparable differentiation potential of iMSCs and JPCs. Additionally, iMSCs showed significantly longer telomere lengths compared to JPCs indicating rejuvenation of the cells during reprogramming. On the other hand, proliferation, mitochondrial activity, and senescence-associated beta-galactosidase (SA-β-gal) activity indicated early senescence of iMSCs. These data demonstrate the requirement of further optimization strategies to improve mesenchymal development of JPC-derived iPSCs in order to take advantage of the best features of reprogrammed and rejuvenated cells.

Abstract A52: Modulation of Hedgehog signaling alters immune infiltration in pancreatic cancer

Abstract Background: Pancreatic ductal adenocarcinoma (PDA) has a dismal 5-year survival rate of 9%, making this disease one of the deadliest human malignancies. Primary barriers to the treatment of pancreatic cancer include extensive stromal interactions and sustained immune suppression. Aberrant Hedgehog (HH) pathway activity is a hallmark of pancreatic tumorigenesis. Tumor-derived HH ligands signal in a paracrine fashion to the surrounding stroma to influence tumor growth. Expression of HH ligands increases during PDA progression, and previous work has shown that genetic deletion of Sonic HH from the epithelium of mice with pancreatic tumors results in increased Indian HH (Ihh) expression. Methods: Ihh was deleted in tumor cells lines (IhhKO) derived from a genetically engineered mouse model of pancreatic cancer (KrasG12D;Trp;P48-Cre), using CRISPR/Cas-9 gene editing to assess the role of Ihh in the tumor microenvironment. The level of HH signaling was determined using tumor cell co-cultures with Gli1lacZ fibroblasts (derived from mice with a lacZ reporter allele knocked into the Gli1 locus), in which beta galactosidase activity serves as a readout for HH signaling. WT and IhhKO tumor cells were orthotopically transplanted into the pancreas of syngeneic C57BL/6 mice. Human pancreas samples were obtained from surgical resection of pancreatic adenocarcinoma or fine-needle biopsy procedure (FNB). Immune profiling of mouse and human pancreatic tumors was performed using Cytometry Time-of-Flight analysis, and tumor composition was analyzed by single-cell RNA sequencing. In vitro cultures with pancreatic fibroblasts treated with either WT or IhhKO tumor cell conditioned media (CM) were cultured to assess tumor crosstalk. Results: Tumor cells lacking Ihh were generated through CRISPR/Cas-9 deletion, and this was confirmed by qRT-PCR. Co-culture of IhhKO tumor cells with Gli1lacZ fibroblasts results in decreased Gli1 expression both in vitro and in vivo. Immune profiling revealed that tumors lacking Ihh have significantly fewer macrophages (CD11b+/F4/80+), resulting in decreased presence of immunosuppressive factors such as arginase 1 and PDL1. Immune profiling of human PDA revealed similar populations of immunosuppressive myeloid cells present in tumors. In vitro co-cultures demonstrated CCL2 expression was reduced in pancreatic fibroblasts cultured with IhhKO-CM, providing mechanistic insight into the in vivo phenotype observed. Further, scRNA seq analysis suggests that modulation of HH signaling in the tumor microenvironment alters chemokine and immunomodulatory signaling pathways driven by fibroblasts in the pancreatic tumor microenvironment. Significance of Impact: HH signaling in pancreatic fibroblasts contributes to the establishment of an immune-suppressive environment in pancreatic cancer. Combining methods to target HH signaling and immune checkpoint therapy has translational potential in treating pancreatic cancer patients. Citation Format: Nina Steele, Samantha Kemp, Valerie Irizarry-Negron, Veerin Sirihorachai, Ahmed Abbas, Eileen Carpenter, Christopher Halbrook, Carlos Espinoza, Costas Lyssiotis, Howard Crawford, Timothy Frankel, Filip Bednar, Ben Allen, Marina Pasca di Magliano. Modulation of Hedgehog signaling alters immune infiltration in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr A52.

Characterization of human telomerase reverse transcriptase immortalized anterior cruciate ligament cell lines

BackgroundThe anterior-cruciate-ligament (ACL) contains mesenchymal stem cells (ACL-MSCs), suggesting the feasibility of regenerative treatments of this tissue. The immortalization of isolated cells results in cell-lines applicable to develop cell-based therapies. Immortal cell lines eliminate the need for frequent cell isolation from donor tissues. The objective of this study was to characterize cell lines that were generated from isolated ACL-MSCs using TERT gene transfer. MethodsWe isolated ACL-MSCs from human ACLs derived at the time of ACL reconstruction surgery or total knee arthroplasty. We generated cell lines and compared them to non-immortalized ACL-MSCs. We assessed the cellular morphology and we detected surface antigen expression. The resistance to senescence was inferred using the beta galactosidase activity. Histology, immunohistochemistry, and reverse transcriptase polymerase chain reaction (RT-PCR) were used to evaluate the multilineage differentiation capacity. ResultsThe morphology of hTERT-ACL-MSCs was similar to ACL up to the last assessment at passage eight. We detected a strong surface expression of CD44, CD90, CD105, and STRO-1 in hTERT-ACL-MSCs. No substantial reduction in the ATP activity was observed in hTERT-ACL-MSCs. ConclusionCell lines generated from ACL-MSCs maintain their morphology, surface antigen expression profile, and proliferative capacity; while markers of senescence appear to be reduced. These cell-lines maintained their multilineage differentiation capacity. The demonstrated model systems can be used for further development of new cell-based regenerative approaches in anterior cruciate ligament research, which may lead to new therapeutic strategies in the future.

Decreased Activity of Blood Acid Sphingomyelinase in the Course of Multiple Myeloma.

Acid sphingomyelinase (aSMase) is involved in the generation of metabolites that function as part of the sphingolipid signaling pathway. It catalyzes the breakdown of sphingomyelin into ceramide, a bioactive lipid that, among other roles, is involved in regulation of apoptosis. Dry drop blood test (DBS) and colorimetric 2-step enzymatic assay were used to assess the activity of human blood aSMase, beta-galactosidase, and beta-glucosidase, these enzymes are lysosomal hydrolases that catalyze the degradation of related sphingolipids, of sphingolipid signaling molecules. Blood was collected from a group of healthy volunteers and patients that were diagnosed with multiple myeloma (MM) in various stages of the disease. Additionally, activity of those enzymes in patients diagnosed with other hematological cancers was also assessed. We found that aSMase activity in the blood of patients with MM (at the time of diagnosis) was 305.43 pmol/spot*20 h, and this value was significantly lower (p < 0.030) compared to the healthy group 441.88 pmol/spot*20 h. Our collected data suggest a possible role of aSMase in pathogenesis of MM development.

Stromal Cell-Derived Factor 1 Protects Brain Vascular Endothelial Cells from Radiation-Induced Brain Damage.

Stromal cell-derived factor 1 (SDF-1) and its main receptor, CXC chemokine receptor 4 (CXCR4), play a critical role in endothelial cell function regulation during cardiogenesis, angiogenesis, and reendothelialization after injury. The expression of CXCR4 and SDF-1 in brain endothelial cells decreases due to ionizing radiation treatment and aging. SDF-1 protein treatment in the senescent and radiation-damaged cells reduced several senescence phenotypes, such as decreased cell proliferation, upregulated p53 and p21 expression, and increased senescence-associated beta-galactosidase (SA-β-gal) activity, through CXCR4-dependent signaling. By inhibiting extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription protein 3 (STAT3), we confirmed that activation of both is important in recovery by SDF-1-related mechanisms. A CXCR4 agonist, ATI2341, protected brain endothelial cells from radiation-induced damage. In irradiation-damaged tissue, ATI2341 treatment inhibited cell death in the villi of the small intestine and decreased SA-β-gal activity in arterial tissue. An ischemic injury experiment revealed no decrease in blood flow by irradiation in ATI2341-administrated mice. ATI2341 treatment specifically affected CXCR4 action in mouse brain vessels and partially restored normal cognitive ability in irradiated mice. These results demonstrate that SDF-1 and ATI2341 may offer potential therapeutic approaches to recover tissues damaged during chemotherapy or radiotherapy, particularly by protecting vascular endothelial cells.

Thrombin Induces Angiotensin II-Mediated Senescence in Atrial Endothelial Cells: Impact on Pro-Remodeling Patterns.

Background: Besides its well-known functions in hemostasis, thrombin plays a role in various non-hemostatic biological and pathophysiologic processes. We examined the potential of thrombin to promote premature atrial endothelial cells (ECs) senescence. Methods and Results: Primary ECs were isolated from porcine atrial tissue. Endothelial senescence was assessed by measuring beta-galactosidase (SA-β-gal) activity using flow cytometry, oxidative stress using the redox-sensitive probe dihydroethidium, protein level by Western blot, and matrix metalloproteinases (MMPs) activity using zymography. Atrial endothelial senescence was induced by thrombin at clinically relevant concentrations. Thrombin induced the up-regulation of p53, a key regulator in cellular senescence and of p21 and p16, two cyclin-dependent kinase inhibitors. Nicotinamide adenine dinucleotide phosphate NADPH oxidase, cyclooxygenases and the mitochondrial respiration complex contributed to oxidative stress and senescence. Enhanced expression levels of vascular cell adhesion molecule (VCAM)-1, tissue factor, transforming growth factor (TGF)-β and MMP-2 and 9 characterized the senescence-associated secretory phenotype of atrial ECs. In addition, the pro-senescence endothelial response to thrombin was associated with an overexpression of both angiotensin converting enzyme and AT1 receptors and was inhibited by perindoprilat and losartan. Conclusions: Thrombin promotes premature ageing and senescence of atrial ECs and may pave the way to deleterious remodeling of atrial tissue by a local up-regulation of the angiotensin system and by promoting pro-inflammatory, pro-thrombotic, pro-fibrotic and pro-remodeling responses. Hence, targeting thrombin and/or angiotensin systems may efficiently prevent atrial endothelial senescence.

P3485Autophagy insufficiency participates in hyperhomocysteinemia-induced cardiac aging

Abstract Background The elevated plasma homocysteine (Hcy) level can lead to severe cardiovascular injuries, which participates in the progression of atherosclerosis, heart failure and so on. Except cardiovascular diseases, accumulated researches further revealed that hyperhomocystenemia (HHcy) can also induce aging-related diseases, including Alzheimer's disease, Parkinson's disease, diabetic cardiomyopathy, etc. Though some researches had revealed that Hcy stimulation would lead to endothelial cells senescence, whether cardiac aging could be induced by HHcy still remain unknown. Purpose This study aimed to reveal whether HHcy can induce cardiac aging and the underlying mechanisms. Methods SD rats were utilized to establish HHcy rat model and natural aging rat model. The cardiac function were determined by Echocardiography. Transmission electron microscope were used to detect mitochondria injuries of myocardium. 18F-FDG PET/CT was used to detect the state of glucose metabolism in myocardial cells. Agilent mRNA Array was used to detect possible altered pathways in myocardium of HHcy rats. The autophagy level was determined by detection of both autophagy-related proteins expressions with Western Blot and autophagic flux with mRFP-GFP-LC3. Results HHcy rats showed overall aging phenotypes, which were consistent with natural aging rats. The impaired cardiac function and severely injured myocardium morphology were observed in HHcy rats. Aging-related markers were increased significantly in HHcy rats and Hcy-treated cells, presented as increased p16, p21 and p53 expressions and increased senescence-associated beta-galactosidase (SA-β-gal) activity. Mitochondria dysfunction and morphology injuries were also detected in HHcy rats. Moreover, decreased serum Beclin-1 level was tested in CHD patients with HHcy. The decreased autophagy level was further verified in HHcy rats and Hcy-treated cells. Furthermore, the over-expression of Atg5 could attenuate Hcy induced cellular senescence. Conclusion HHcy can reduce autophagy level, which leading to severe mitochondria injuries, and resulted in cardiac aging eventually. Acknowledgement/Funding Natural Science Foundation of China (81671382,91839107)

P6266Circulating microparticules of patients with coronary artery disease up-regulate the expression of sodium-glucose cotransporters 1 and 2 in coronary artery endothelial cells: role of angiotensin II

Abstract Introduction Circulating microparticles (MPs) from patients with coronary artery diseases (CAD) have been shown to promote endothelial senescence and dysfunction involving the pro-oxidant local angiotensin system. Sodium-glucose cotransporters (SGLTs)2 inhibitors decreased the risk of cardiovascular disease in patients with type 2 diabetes and this effect appears to be independent of glycemic control. Moreover, high glucose and H2O2 have been shown to cause a redox-sensitive upregulation of SGLT1 and 2 in coronary artery endothelial cells (ECs). Aim Therefore, this study examined whether angiotensin II (Ang II, a potent NADPH oxidase-dependent inducer of oxidative stress) and CAD MPs stimulate SGLT1 and 2 expression in ECs, and assessed their role in the induction of endothelial dysfunction. Methods ECs were isolated from porcine coronary arteries. The protein expression level was assessed by Western blot analysis and immunocytochemical staining, oxidative stress using dihydroethidium staining, and senescence by senescence-associated beta-galactosidase activity (SA-beta-gal activity). Circulating CAD MPs were collected from blood samples of patients (61–79 year) with established cardiovascular disease. Results Control ECs expressed low levels of SGLT1 and SGLT2 proteins. Exposure of ECs to Ang II caused a time- and concentration-dependent increase in the protein level of SGLT1 and SGLT2 with a significant increase observed at concentrations as low as 10 nM. Exposure of ECs to CAD MPs (10 nM PhtdSer eq) from 3/5 patients increased the SGLT1 and SGLT2 protein level. An increased SGLT1 and SGLT2 immunofluorescence signal was also observed in response to Ang II and H2O2. Ang II increased the level of oxidative stress, SA-beta-gal activity, senescence markers (p53, p21 and p16), VCAM-1, MCP-1, tissue factor (TF) and the local angiotensin system (ACE, AT1R), and down-regulated that of eNOS. CAD MPs from 4/5 patients decreased eNOS level and from 5/5 patients increased VCAM-1 level. All the Ang II-induced effects were prevented by the dual SGLT1/2 inhibitor LX-4211 and the selective SGLT2 inhibitor, empagliflozin. Conclusions The present findings indicate that CAD MPs and Ang II upregulate the expression of SGLT1 and SGLT2 protein levels in ECs, and that they promote endothelial dysfunction. They further suggest that inhibition of SGLT1 and/or SGLT2 might be an attractive strategy to protect the arterial wall and, hence, the development of cardiovascular diseases. Acknowledgement/Funding Unrestricted research grant from Boehringer Ingelheim Pharma GmbH &amp; Co. KG