Lgr5 Expression Research Articles

An LGR6 frameshift variant abrogates receptor expression on select leukocyte subsets and is associated with viral infections

AbstractThe leucine-rich repeat-containing G-protein–coupled receptor 6 (LGR6) was recently identified as the cognate receptor for the proresolving mediator maresin 1 (MaR1). To address the biological role of LGR6 in humans, we investigated the functional impact of a genetic variant in the gene encoding for LGR6, which is predicted to lead to a frameshift mutation in one of the receptor isoforms, on both receptor expression and immune cell responses. In neutrophils, monocytes, and natural killer (NK) cells from volunteers homozygous for this variant, we found a significant downregulation in the expression of LGR6 when compared with controls without the variant; whereas the LGR6 expression was essentially similar in monocyte-derived macrophages and CD8+ T cells. Functionally, loss of LGR6 expression was linked with a decreased ability of neutrophils and monocytes to phagocytose bacteria. We observed an increase in neutrophil chemotaxis and leukotriene B4 production and increased expression of activation markers, including markers for platelet-leukocyte phagocyte heterotypic aggregates, such as CD41, in neutrophils and monocytes from the variant group. Using data from the UK Biobank, we found that at a population level the rs4266947 variant, which is in high linkage disequilibrium with rs74355478, was associated with a higher incidence of viral infections. Intriguingly, neutrophils, NK cells, and CD8+ T cells from volunteers with the LGR6 variant displayed altered viral responses when stimulated with Toll-like receptor 3 (TLR3), TLR7/TLR8, and TLR9 agonists. Together, these findings shed new light on the cell type–specific regulation of LGR6 expression and the role of this receptor in directing host immune responses.

Partially Differentiated Ileal and Rectal Human CFTR-F508del Enteroids Secrete Fluid in Response to cAMP and cGMP: Targeted Preclinical Studies of Pharmaco-Therapy of CF Constipation

Introduction: Treatment of Cystic Fibrosis (CF) patients with Trikafta is prolonging life. This has allowed the importance of other causes of morbidity in these patients to become clearer and to emphasize the need to improve their quality of life by developing additional treatments. Chronic constipation is one such continuing unsolved medical issue for patients with CF even on Trikafta. In general, approaches to treat chronic constipation include increasing intestinal fluid secretion that involves inhibiting intestinal NaCl absorption and/or stimulating intestinal Cl secretion, with inhibition of the latter being the primary defect in CF. Drug development efforts have mostly aimed to improve CFTR function and control pancreatic insuffciency. We have recently reported an enterocyte population in the human ileal and colon that is present between the crypt Cl− secretory cells and the mature small intestinal villus or colonic surface Na+ absorptive cells that contain both DRA and CFTR. This population is called partially differentiated enterocytes. This study was undertaken to derive a strategy to stimulate intestinal fluid secretion from partially differentiated enterocytes in the F508del-CF-patient population by enhancing residual CFTR F508del activity using drugs that stimulate cAMP and cGMP. Methods: Ileal and rectal enteroids from F508del CF patients and healthy subjects (HS/normal) were studied. Enteroids were maintained in growth media containing Wnt3A, R-spondin, and Noggin (undifferentiated/UD); induced to partially differentiate (3d-DF) or fully differentiate (6d-DF) by removal of growth factors (Wnt3A and R-spondin) for 3 or 6 days, respectively. Forskolin-induced swelling (FIS) assay and live cell microscopy were used to determine fluid secretion in enteroids. A relative increase in organoid surface area over a time series of 60 min was measured to quantify FIS response. mRNA expression was determined using qRT-PCR. Results: Compared to HS enteroids, F508del enteroids had significantly higher mRNA expression of LGR5, and Ki67 in the UD state. Expression of goblet cell marker MUC2 and enteroendocrine (EEC) marker ChgA increased with differentiation in both HS and F508del, while 6d-DF F508del enteroids had a significantly higher ChgA compared to 6d-DF enteroids from HS. UD F508del enteroids had significantly higher expression of phosphodiesterase-3a (PDE3a) than HS enteroids, which further increased with differentiation, but did not change in HS. While UD and 6d-DF F508del rectal and ileal enteroids did not swell when exposed to cAMP (forskolin) and cGMP (linaclotide), 3d-DF F508del enteroids showed a swelling response when exposed to cAMP (forskolin) and cGMP (linaclotide). Fluid secretion from 3d-DF F508del enteroids was ~50% (cAMP) and ~67% (cGMP) of the response of intestinal enteroids from HS enteroids. Combinations of CFTR correctors and potentiators mimicking the makeup of Trikafta only partially enhanced fluid secretion in F508del CF enteroids as compared to HS. However, cGMP (linaclotide) additively enhanced Trikafta-induced fluid secretion from 3d-DF F508del enteroids. Conclusions: CFTR F508del can be stimulated by cAMP and cGMP in partially differentiated enterocyte populations. Our findings identify a novel role of the partially differentiated ileal and rectal enterocyte populations which behave in a way that offers the potential to improve treatment for CF constipation. Funding: This study is partly supported by Cystic Fibrosis Foundation grant CF-SINGH20G0, National Institutes of Health grants R01-DK-116352 and P30-DK-89502 (the Hopkins Basic and Translational Research Digestive Diseases Research Core Center). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Environmentally relevant concentrations of benzophenones exposure disrupt intestinal homeostasis, impair the intestinal barrier, and induce inflammation in mice

The aim of this study is to investigate the adverse effects of benzophenones (BPs) on the intestinal tract of mice and the potential mechanism. F1-generation ICR mice were exposed to BPs (benzophenone-1, benzophenone-2, and benzophenone-3) by breastfeeding from birth until weaning, and by drinking water after weaning until maturity. The offspring mice were executed on postnatal day 56, then their distal colons were sampled. AB-PAS staining, HE staining, immunofluorescence, Transmission Electron Microscope, immunohistochemistry, Western Blot and RT-qPCR were used to study the effects of BPs exposure on the colonic tissues of offspring mice. The results showed that colonic microvilli appeared significantly deficient in the high-dose group, and the expression of tight junction markers Zo-1 and Occludin was significantly down-regulated and the number of goblet cells and secretions were reduced in all dose groups, and the expression of secretory cell markers MUC2 and KI67 were decreased, as well as the expression of intestinal stem cell markers Lgr5 and Bmi1, suggesting that BPs exposure caused disruption of intestinal barrier and imbalance in the composition of the intestinal stem cell pool. Besides, the expression of cellular inflammatory factors such as macrophage marker F4/80 and tumor necrosis factor TNF-α was elevated in the colonic tissues of all dose groups, and the inflammatory infiltration was observed, which means the exposure of BPs caused inflammatory effects in the intestinal tract of F1-generation mice. In addition, the contents of Notch/Wnt signaling pathway-related genes, such as Dll-4, Notch1, Hes1, Ctnnb1and Sfrp2 were significantly decreased in each high-dose group (P < 0.05), suggesting that BPs may inhibit the regulation of Notch/Wnt signaling pathway. In conclusion, exposure to BPs was able to imbalance colonic homeostasis, disrupt the intestinal barrier, and trigger inflammation in the offspring mice, which might be realized through interfering with the Notch/Wnt signaling pathway.

ERdj5-mediated regulation of proliferation and differentiation in colon organoids under inflammatory stress

Background: Endoplasmic reticulum (ER) stress is resolved by ERdj5, which functions as a disulfide reductase. In a previous study, we confirmed that ERdj5 was not indispensable for the formation of intestinal epithelial cells in mice. However, studies evaluating the association of ERdj5 and growth factors are limited. In the present study, we observed changes in the proliferation of colon organoids cultured from intestinal crypts obtained from wild-type (WT) and ERdj5 knockout (KO) mice.Methods: We cultured colon organoids from WT and ERdj5 KO mice, and we then assessed differentiation- and proliferation-related markers after exposure to various stimuli, such as irradiation and the Toll-like receptor (TLR) 2 ligand Pam3CSK4.Results: Over 15 days of organoid culture, ERdj5 KO colon organoids demonstrated a similar increase in leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) expression as WT colon organoids. However, in response to Pam3CSK4-induced stress, the ERdj5 KO organoids exhibited decreased Lgr5 expression and increased C/EBP homologous protein (CHOP) levels. Moreover, after irradiation-induced stress, ERdj5 downregulated epithelial-related genes, including Lgr5, Villin 1, and Prominin 1.Conclusion: Inflammation through irradiation or TLR2-induced mild or severe ER stress in both groups, whereas ERdj5 deficiency eventually led to the downregulation of Lgr5. In summary, these findings suggest that colon organoids lack the ability to mount an effective defense against various inflammatory stimuli when there is a deficiency in the ERdj5-related ER stress resolution pathway.

Abstract 3901: Therapeutic targeting of LGR5-positive cancer stem cells

Abstract Introduction: Destruction of cancer stem cells (CSC) is a major therapeutic goal. LGR5 marks active stem cells in many types of solid cancers. It has been very difficult to isolate good antibodies to native LGR5 and attempts to develop ADCs targeting LGR5 have not advanced. We took the alternative approach of using a natural LGR5 ligand to target monomethylauristatin (MMAE) to LGR5-expressing CSC. An Fc domain was fused to the LGR binding domains of RSPO1 and the sortase reaction was used to conjugate a Gly3-val/cit-PAB-MMAE linker at the C-terminal end to create FcF2-MMAE. We previously reported its efficacy in ovarian models here document its activity in other aggressive cancer models. Methods: FcF2-MMAE was produced by transient transfection in HEK293E cells and purified by a sequential Ni-NTA and ion exchange chromatography. OVCAR8 ovarian cancer cells were molecularly engineered to stably express an empty vector (OVCAR8/EV) or LGR5 (OVCAR8/LGR5.6) at a 10-fold higher level. The sortase A enzyme was produced in E. coli. Flow cytometry was used to quantify cell surface LGR5 in live cells using an anti-LGR5 antibody. Results: DEPMAP tools were used to identify cell types with high levels of WNT signaling that drives expression of LGR5. FCM confirmed LGR5 expression in colon LoVo, gastric AGS and neuroblastoma SKNAS cells. All three lines were very sensitive to FcF2-MMAE; GI50 values in 2D cultures were: LoVo 4.5, AGS 0.7 and SKNAS 8.6 nM. IC50 values for stem cell-derived spheroids grown from these lines were: 11.0, 3.0 and 1.70 nM, respectively. The MTD of FcF2-MMAE was found to be &amp;gt;1.5 nmol/g in mice. The plasma half-life was 29.7 h. A q7dx4 IP dose schedule was found to be more effective than a q4dx4 IP schedule. FcF2-MMAE inhibited in vivo SC growth in all 3 models at a dose of 1 nmol/g q7dx4, producing cures in a fraction of AGS tumors and delaying SKNAS growth &amp;gt;2-fold in the absence adverse events. In addition to MMAE, we showed that FcF2-His could be conjugated to the either deruxtecan or PNU159682; FcF2-His loaded with either one of these cytotoxins had low nM or sub nM cytotoxicity and retained the same high selectivity of FcF2-MMAE when tested in isogenic OVCAR8/EV and OVCAR8/LGR5 cells. Conclusions: FcF2-MMAE has activity in xenograft models of very aggressive tumors driven by high levels of WNT signaling (LoVo, AGS, and SKNAS) and LGR5 expression. Efficacy was obtained at doses well below its MTD indicating a wide therapeutic window. The FcF2 core accommodates multiple types of warheads without loss of targeting selectivity. The ability to switch out one cytotoxin for another provides versatility in targeting different diseases. FcF2-MMAE has advantages over ASCs. Its small size relative to antibodies favors better tumor penetration. The binding domains of RSPO1 also target stem cells expressing LGR4 and LGR6 as well as LGR5, something that cannot be achieved with an ADC. These features support the further development of FcF2-MMAE as a stem cell-targeted therapeutic. Citation Format: Maria Carmen Mulero, Catherine Rice, Sukshala A. Jahdav, Willie Pi, Alexander Lin, Mindy Nguyen, Owen Tai, Stephen B. Howell. Therapeutic targeting of LGR5-positive cancer stem cells [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 3901.

Abstract 4552: EGFR inhibitors increase LGR5 expression and enhance potency of LGR5 antibody-drug conjugates targeting colorectal cancer stem cells

Abstract Colorectal cancer (CRC) is the second leading cause of cancer-associated deaths in the United States. One of the primary challenges in treating CRC is therapy resistance thought to be mediated by cancer stem cells (CSCs), a subpopulation of cancer cells with infinite replicative potential that can differentiate to drive tumorigenesis and disease relapse. Antibody-drug conjugates (ADCs) are amongst the fastest growing classes of anticancer drugs and utilize the specificity of monoclonal antibodies (mAbs) to hone cytotoxic payloads to cancer cells. We generated ADCs directed against leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5), a well-defined biomarker of CSCs that is highly overexpressed in CRCs. LGR5 ADCs demonstrated high specificity and efficacy in CRC cells and xenograft models, though tumor relapse after treatment withdrawal was a major obstacle. Interestingly, FDA-approved therapy targeting epidermal growth factor receptor (EGFR) has been shown to increase LGR5 mRNA expression levels in patient-derived models of CRC. This study aims to determine the mechanism of EGFR-mediated regulation of LGR5 expression and evaluate the therapeutic efficacy of combination treatments targeting EGFR and LGR5 for the improved treatment of CRC. To first analyze the effect of EGFR inhibition on LGR5 expression, a panel of CRC cell lines of different KRAS and PI3CKA mutational statuses were treated with FDA-approved EGFR-targeted mAbs or small molecule inhibitors. LGR5 protein expression was shown to be upregulated by EGFR-targeted therapies in a dose- and time-dependent manner, independent of mutation status. Notably, treatment with EGF, MEK1/2 inhibitor trametinib, and EGFR-directed siRNA all resulted in concomitant reduction in EGFR and LGR5 protein levels, suggesting EGFR and LGR5 are co-degraded. Co-immunoprecipitation and immunocytochemistry experiments identified a novel EGFR-LGR5 interaction and co-internalization mechanism in CRC cells, respectively. Furthermore, we showed EGFR-LGR5 interaction is enhanced by treatment with the EGFR-targeting mAb, cetuximab (CTX). To evaluate efficacy of combination therapies targeting EGFR and LGR5, CRC cells were treated with LGR5 ADCs with or without CTX. Importantly, we showed CTX significantly enhanced the potency of LGR5 ADCs incorporating different classes of cytotoxic payloads. These results suggest combining LGR5 ADCs with EGFR inhibitors may be a more effective approach for the treatment of CRC and eliminating CSCs to overcome resistance and relapse. Citation Format: Peyton C. High, Zhengdong Liang, Kendra S. Carmon. EGFR inhibitors increase LGR5 expression and enhance potency of LGR5 antibody-drug conjugates targeting colorectal cancer stem cells [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 4552.

Abstract 6320: CAR-T cells targeting LGR5: An effective treatment for chemotherapy resistant ovarian cancer

Abstract Ovarian cancer is the second leading cause of cancer-related mortality among gynaecological cancers in the Western world. CAR-T cell therapy is an adoptive immunotherapy used to treat some blood cancers. This study has investigated whether leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) is a suitable target for CAR-T cell therapy for ovarian cancer. We assessed the cytotoxic effects of LGR5-targeting CAR-T cells on a range of ovarian cancer cell lines and primary serous ovarian cancer cells derived from patient ascites (at diagnosis and following relapse with chemotherapy resistant disease) in monolayer culture, 3D spheroid assays and patient-derived explant assays. OVCAR3 and a chemoresistant patient-derived xenograft (PDX) models have been used to assess whether LGR5-targeting CAR-T cells can inhibit growth and metastasis in vivo. We found that LGR5 is highly expressed in high-grade serous ovarian carcinoma (HGSOC) cancer cell lines and LGR5 expression was increased in chemotherapy resistant primary ovarian cancer cells. We demonstrated that LGR5-targeting CAR-T cells were cytotoxic and significantly inhibited the survival of ovarian cancer cell lines and chemotherapy-resistant primary ovarian cancer cells with high LGR5 expression levels in both monolayer culture and 3D spheroids compared to un-transduced CD3+ T cells. In patient-derived explant assays, we observed increased apoptosis in HGSOC tissues expressing high LGR5 following treatment with LGR5-targeting CAR-T cells. In vivo, LGR5-targeting CAR-T cell treatment decreased the tumour burden in mice with OVCAR3 xenografts and a chemotherapy-resistant PDX model with high LGR5 expression, compared to CD3+ T cells. In summary, LGR5-targeting CAR-T cells have great potential to be developed as a novel immunotherapy for ovarian cancer. Citation Format: Wanqi (Jady) Wang, Veronika Bandara, Noor A. Lokman, Zoe K K. Price, Tannith M. Noye, Silvana Napoli, Batjargal Gundsambuu, Martin K. Oehler, Simon C. Barry, Carmela Ricciardelli. CAR-T cells targeting LGR5: An effective treatment for chemotherapy resistant ovarian 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 6320.

Abstract 266: The effects of retinoid agents and retinoic acid receptor genotype on proliferation, differentiation, and stem cells in colorectal cancer

Abstract Understanding how to therapeutically target colonic stem cells (SCs) is important because SC overpopulation drives CRC growth and development. Our goal is to therapeutically sensitize cancer SCs (CSCs) to the differentiation-inducing effects of retinoid agents. We previously found that ALDH specifically marks normal and malignant colonic SCs. We also found that retinoic acid (RA) receptors and other RA signaling components are selectively expressed in ALDH+ SCs, indicating that RA signaling occurs through ALDH+ SCs. Because all-trans retinoic acid (ATRA) is a highly effective treatment for acute promyelocytic leukemia, which is caused by a genetic translocation involving retinoic acid receptor alpha (RARA), we conjecture that the response of RA agents may be effective against solid tumors depending on their pathway genotype. Our bioinformatics analysis on mutations and overexpression of RA signaling component genes in CRC showed that most of the RA pathway genes are altered in human CRCs. Therefore, we hypothesize that the ability of retinoid agents and retinoid metabolism blocking agents to induce differentiation of CSCs depends on the RA pathway genotype of CRC cells.Testing the effect of various retinoid drugs on cell proliferation shows that RA pathway genotype affects the response of RA agents in CRC cell lines. HCT116 and SW480 CRC cell lines, which have RA receptor mutations, displayed resistance to ATRA. In contrast, HT29 CRC cells that have wild-type RA receptors are sensitive to ATRA. All three cell lines however showed similar dose responses to the ATRA metabolizing enzyme, CYP26A1 inhibitor Liarozole. This finding indicates that regardless of RA receptor mutations, inhibition of ATRA metabolism can increase intracellular RA levels in a similar manner on all three cell lines to induce anti-proliferative effects. We used CRISPR-Cas9 gene editing to knock out the RARA gene in HT29 cells and evaluated its response to ATRA compared to HT29 cells. The RARA knockout derived lines showed reduced sensitivity to ATRA treatment and a slower rate of cell division compared to HT29 control cells. Additionally, Nanostring mRNA profiling analysis shows that ATRA treatment of HT29 cells increases expression of RARA, CYP26A1, and KRT20 (differentiation marker); and decreased decreases expression of CSC markers LGR5 and ALDH1A1. Altogether, these findings indicate that upregulated RA signaling can reduce cell proliferation, increase differentiation, and decrease CSC numbers in CRCs. Overall, our findings indicate that colon SCs are regulated by RA signaling mechanisms and dysregulation of RA signaling contributes to the SC overpopulation that drives CRC growth. Thus, therapeutically sensitizing CSCs to differentiation-inducing effects of retinoid agents should provide insight into designing new SC-targeted therapies for CRC. Citation Format: Victoria O. Hunsu, Caroline O. Facey, Bruce M. Boman. The effects of retinoid agents and retinoic acid receptor genotype on proliferation, differentiation, and stem cells in colorectal 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 266.

Abstract 6982: The roles of NDRG1 in HCC progression and its clinical significance

Abstract Background: Hepatocellular carcinoma (HCC) is prevalent globally and the third leading cause of cancer-related mortality. N-myc downstream regulated 1 (NDRG1) was found to be tumor promoting in some cancers while suppressive in others. The expression of NDRG1 is induced by stress signals such as DNA damage and hypoxia. In HCC, it has been found to promote proliferation and metastasis. Contradictory results, however, were also suggested on the functions of NDRG1. Methods: Our own HCC cohort and multiple publicly available databases were examined for NDRG1 expression and clinicopathologic correlation. NDRG1 expression under hypoxic conditions was investigated. Various functional assays were performed for NDRG1-knockdown HCC cell lines Huh-7 and PLC/PRF/5. Results: With RT-qPCR analysis on our 102 pairs of patients’ HCC tumor and corresponding non-tumorous liver samples, we found NDRG1 to be upregulated in HCC tumors. Similarly, RNA-sequencing analysis comparing 41 pairs of samples confirmed NDRG1 enrichment in HCC tumors. The upregulation was significantly and positively correlated with the absence of tumor encapsulation and cellular differentiation. These were further supported by TCGA and ICGC databases, in which upregulation of NDRG1 was significantly correlated with poor HCC patient overall survival. Interestingly, in the TCGA database, only 17% of the HCC cases were inferred to have copy number amplification of NDRG1 gene while NDRG1 mutations were rarely found. As hypoxia is a major tumor microenvironmental factor in HCC, we investigated NDRG1’s expression level in HCC cells under hypoxic or normoxic conditions and found significant increase in NDRG1 expression under hypoxic environment. We further found that NDRG1 knockdown inhibited cell proliferation, self-renewal ability, and migration. RT-qPCR analysis found lower LGR5 and SOX2 expression upon NDRG1 knockdown. This is in line with the positive correlation between NDRG1 and various cancer stemness-related gene expression, including LGR5, CD24, MYC, SOX2, and NOTCH1, in TCGA database. Lastly, in the resected HCC tumors on which spatial transcriptomics using Visium 10X and single-cell RNA-sequencing using Chromium 10X were performed, we found NDRG1 enrichment in both tumors cells and cancer associated fibroblasts (CAFs). Conclusion: NDRG1 was found to be significantly upregulated in HCC cells in our in-house cohort and publicly available databases. NDRG1 consistently promotes various oncogenic features of HCC cells, including proliferation, self-renewal ability, and migration. In addition, NDRG1 was found to be enriched in both the HCC cells and CAFs. Citation Format: Jingyi Lu, Lu Tian, Yu-Man Tsui, Xia Wong, Qingyang Zhang, Daniel Wai-Hung Ho, Irene Oi-Lin Ng. The roles of NDRG1 in HCC progression and its clinical significance [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 6982.

Abstract 56: Preclinical in vivo characterization underpinning LGR5-targeting CAR-T cells as a cancer immunotherapy

Abstract Incidences of early-onset colorectal cancer (CRC) have been accelerating worldwide. To begin to address the lack of therapeutic options for CRC, we have developed a CAR-T cell therapy specific for leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5). LGR5 is known to potentiate Wnt/Β-catenin signaling and mark cells-of-origin in intestinal cancers. Extensive screening has demonstrated elevated expression of LGR5 in CRC, which is correlated with reduced patient survival. In CRC, LGR5 has been intimately linked with metastasis, cell survival and perturbation of chemotherapeutic interventions. We have developed a 9-day preclinical manufacturing method to generate LGR5-targeting CAR-T cells with a minimally differentiated T cell phenotype, which was concomitant with significant cytotoxic and activation marker expression. In human CRC xenograft mouse models, LGR5-targeting CAR-T cells eradicated tumors at doses as low as 800,000 CAR+ cells, and were capable of significantly inhibiting advanced tumor growth following delayed administration. Robust CAR-T cell-mediated immunological protection was observed in rechallenge experiments, in which secondary tumor growth was undetectable in mice which had tumors rejected following previous CAR-T cell administration. LGR5 protein and mRNA expression was also detected in a diverse range of cancer families, including ovarian, brain, liver and stomach, expanding upon the clinical indications with which LGR5-targeting CAR-T cells may be harnessed. These results contribute to a preclinical body of work that culminated in a Phase I/IIa clinical trial in metastatic colorectal cancer patients, which was approved for initiation by the FDA and commenced in 2023 (NCT05759728). Citation Format: Jade Foeng, Timona Tyllis, Caitlin Abbott, Dylan McPeake, Emma Thompson, Veronika Bandara, Batjargal Gundsambuu, Silvana Napoli, Claudine Bonder, Iain Comerford, Tim Sadlon, Simon Barry, Shaun McColl. Preclinical in vivo characterization underpinning LGR5-targeting CAR-T cells as a cancer immunotherapy [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 56.

Abstract 4551: A novel MET antibody-drug conjugate based combination therapy to overcome colorectal cancer plasticity and drug resistance

Abstract Despite therapeutic advancements, colorectal cancer (CRC) remains the second deadliest malignancy in the United States. Challenges encountered in CRC treatment may be attributed to cancer stem cells (CSC), an immortal tumor cell population. CSCs potentiate tumor relapse by exploiting its infinite replicative potential and inherent drug resistance. Moreover, CSCs exhibit plasticity, allowing them to transition between differentiated and undifferentiated states in response to environmental cues to evade therapy and drive metastatic progression. MET is a receptor tyrosine kinase frequently upregulated in CRCs. We previously demonstrated that treatment with chemotherapies or antibody-drug conjugates (ADCs) targeting the CSC marker LGR5 led to the loss of LGR5 expression with concomitant MET-STAT3 pathway activation in therapy-resistant CRC cells. Further, we showed that LGR5 couples to the scaffold protein IQGAP1, which correlates with poor prognosis in several cancer types. Interestingly, our new data revealed that LGR5 knockdown enhances IQGAP1 interaction with MET and STAT3 via co-immunoprecipitation assays, suggesting a role for IQGAP1 in mediating MET-STAT3 activation and plasticity of LGR5+ CRC cells. To overcome therapy-induced plasticity, we generated MET-targeting ADCs conjugated to DNA-crosslinking payloads. First, we cloned and produced MET monoclonal antibodies (mAbs) and evaluated them for specificity and binding in a panel of CRC cell lines expressing different MET protein levels. MET mAbs demonstrated high selectivity for MET-expressing CRC cells and internalized to lysosomes, which is necessary for ADC payload release. To generate MET ADCs, we employed a site-specific conjugation methodology to attach cleavable peptide linker-drug moieties to the highest affinity MET mAb. MET ADCs were evaluated for cancer cell-killing efficacy in vitro in parallel with MET mAb, non-targeting control mAb (cmAb), and control ADC (cADC). Our MET ADC displayed high potency and efficacy in MET-expressing CRC cells, whereas MET mAb, cmAb, and cADC had minimal effects. MET ADCs were then tested in combination with chemotherapies or other targeted therapies. The combination of MET ADCs with 5-fluorouracil showed a synergistic effect in vitro. Future work involves investigating the safety and efficacy of MET ADCs alone and combined with chemotherapies in xenograft models of CRC. These findings present a mechanism underpinning CRC plasticity and the rationale for a novel treatment modality to potentially overcome CRC resistance and relapse. Citation Format: Shraddha Subramanian, Tressie A. Posey, Joan Jacob, Adela Aldana, Kendra S. Carmon. A novel MET antibody-drug conjugate based combination therapy to overcome colorectal cancer plasticity and drug resistance [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 4551.

Notoginsenoside R1 promotes Lgr5+ stem cell and epithelium renovation in colitis mice via activating Wnt/β-Catenin signaling

Inflammatory bowel disease (IBD) is characterized by persistent damage to the intestinal barrier and excessive inflammation, leading to increased intestinal permeability. Current treatments of IBD primarily address inflammation, neglecting epithelial repair. Our previous study has reported the therapeutic potential of notoginsenoside R1 (NGR1), a characteristic saponin from the root of Panax notoginseng, in alleviating acute colitis by reducing mucosal inflammation. In this study we investigated the reparative effects of NGR1 on mucosal barrier damage after the acute injury stage of DSS exposure. DSS-induced colitis mice were orally treated with NGR1 (25, 50, 125 mg·kg−1·d−1) for 10 days. Body weight and rectal bleeding were daily monitored throughout the experiment, then mice were euthanized, and the colon was collected for analysis. We showed that NGR1 administration dose-dependently ameliorated mucosal inflammation and enhanced epithelial repair evidenced by increased tight junction proteins, mucus production and reduced permeability in colitis mice. We then performed transcriptomic analysis on rectal tissue using RNA-sequencing, and found NGR1 administration stimulated the proliferation of intestinal crypt cells and facilitated the repair of epithelial injury; NGR1 upregulated ISC marker Lgr5, the genes for differentiation of intestinal stem cells (ISCs), as well as BrdU incorporation in crypts of colitis mice. In NCM460 human intestinal epithelial cells in vitro, treatment with NGR1 (100 μM) promoted wound healing and reduced cell apoptosis. NGR1 (100 μM) also increased Lgr5+ cells and budding rates in a 3D intestinal organoid model. We demonstrated that NGR1 promoted ISC proliferation and differentiation through activation of the Wnt signaling pathway. Co-treatment with Wnt inhibitor ICG-001 partially counteracted the effects of NGR1 on crypt Lgr5+ ISCs, organoid budding rates, and overall mice colitis improvement. These results suggest that NGR1 alleviates DSS-induced colitis in mice by promoting the regeneration of Lgr5+ stem cells and intestinal reconstruction, at least partially via activation of the Wnt/β-Catenin signaling pathway.Schematic diagram of the mechanism of NGR1 in alleviating colitis. DSS caused widespread mucosal inflammation epithelial injury. This was manifested by the decreased expression of tight junction proteins, reduced mucus production in goblet cells, and increased intestinal permeability in colitis mice. Additionally, Lgr5+ ISCs were in obviously deficiency in colitis mice, with aberrant down-regulation of the Wnt/β-Catenin signaling. However, NGR1 amplified the expression of the ISC marker Lgr5, elevated the expression of genes associated with ISC differentiation, enhanced the incorporation of BrdU in the crypt and promoted epithelial restoration to alleviate DSS-induced colitis in mice, at least partially, by activating the Wnt/β-Catenin signaling pathway.

Abstract A028: Investigating the role of SOX2 in promoting anchorage-independent survival of ovarian cancer cells

Abstract Ovarian cancer (OVCA) is the most lethal gynecologic malignancy, often detected at an advanced stage. OVCA progression involves transcoelomic metastasis, where tumor cells disseminate into the peritoneal ascites. Malignant cells in the ascites adapt to survive under Anchorage-Independent (A-I) conditions by altering the expression of genes escalating anoikis (A-I cell death) resistance and metastasis. Our lab has shown that OVCA cells manipulate their transcriptomic profile to promote the expression of anoikis resistance genes in A-I. Expression profiling of genes upregulated in A-I revealed the transcription factor SRY-Box Transcription Factor 2 (SOX2) to be highly upregulated in response to OVCA cell detachment. While we have previously demonstrated that SOX2 is necessary for the A-I survival of OVCA cells, the specific mechanism underlying SOX2-dependent A-I survival remains unknown. RNA-sequencing studies performed in the high-grade serous ovarian cancer cell line, OVCAR3, revealed that the Leucine-rich repeat-containing G-protein coupled receptor 5, LGR5, is the most significantly upregulated gene in A-I compared to attached conditions. Importantly, amongst those genes that are upregulated in A-I, LGR5 is significantly downregulated following SOX2 knockdown in A-I. LGR5 is an ‘orphan’ G-protein coupled receptor known to modulate canonical Wnt signaling upon interacting with its ligand R-spondin1 (RSPO1). Time-course experiments in OVCAR3 cells revealed a striking increase in LGR5 expression that peaked after 24 hours in A-I. Furthermore, siRNA mediated knockdown of SOX2 downregulated LGR5 expression only in A-I, suggesting that LGR5 is a potential SOX2 target under A-I conditions. Interestingly, bioinformatics analysis of the existing OVCA datasets from the Cancer Genome Atlas showed increased expression of RSPO1, which correlated with a significant decrease in the overall survival of OVCA patients. Interaction of LGR5 with its ligand RSPO1 is crucial for the receptor to signal through the Wnt pathway to promote cell survival and cancer stemness. Although SOX2 and LGR5 are established markers of cancer stemness in various tumor types, their direct relationship in promoting tumor progression and regulation of OVCA A-I cell survival remains unknown. Our data suggests that increased SOX2 and LGR5 expression could drive OVCA cell survival under A-I conditions. Our current studies focus on understanding the molecular mechanisms behind SOX2-driven regulation of LGR5 and the role of LGR5 in driving OVCA A-I cell survival. Citation Format: Shriya Kamlapurkar, Coryn Stump, Mythreye Karthikeyan, Nadine Hempel. Investigating the role of SOX2 in promoting anchorage-independent survival of ovarian cancer cells [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A028.

Cell cycle heterogeneity and plasticity of colorectal cancer stem cells.

Cancer stem cells (CSCs) are a long-lived and self-renewing cancer cell population that drives tumor propagation and maintains cancer heterogeneity. They are also implicated in the therapeutic resistance of various types of cancer. Recent studies of CSCs in colorectal cancer (CRC) have uncovered fundamental paradigms that have increased understanding of CSC systems in solid tumors. Colorectal CSCs share multiple biological properties with normal intestinal stem cells (ISCs), including expression of the stem cell marker Lgr5. New evidence suggests that colorectal CSCs manifest substantial heterogeneity, as exemplified by the existence of both actively cycling Lgr5+ CSCs as well as quiescent Lgr5+ CSCs that are resistant to conventional anticancer therapies. The classical view of a rigid cell hierarchy and irreversible cell differentiation trajectory in normal and neoplastic tissues is now challenged by the finding that differentiated cells have the capacity to revert to stem cells through dynamic physiological reprogramming events. Such plasticity of CSC systems likely underlies both carcinogenesis and therapeutic resistance in CRC. Further characterization of the mechanisms underpinning the heterogeneity and plasticity of CSCs should inform future development of eradicative therapeutic strategies for CRC.

A61 ELUCIDATING INTESTINAL EPITHELIAL INFLAMMASOME MECHANISMS THAT REPAIR THE MUCOSAL BARRIER DURING ENTERIC INFECTION

Abstract Background To protect the gastrointestinal tract from infection, intestinal epithelial cells (IECs) lining the mucosa possess cytosolic complexes called inflammasomes which detect pathogenic insult and rapidly initiate inflammation to stop infectious spread. Active inflammasomes mediate crucial effector functions such as epithelial cell extrusion, pyroptotic cell death, and the release of interleukin (IL)-18 and prostaglandin E2 (PGE2). Recent literature has shown that IL-18 and PGE2 mediate intestinal repair following epithelial damage from DSS-induced colitis. Exogenous administration of IL-18 in inflammasome deficient mice improves survival and reduces pathology. PGE2 activates intestinal cellular reprogramming to drive intestinal wound healing. Whether inflammasome derived IL-18 and PGE2 mediate epithelial repair during enteric infection is unclear. Aims Using murine small intestinal organoids (mSIOs), we will investigate how IL-18 and PGE2 production by intestinal inflammasomes directly impacts IECs at both transcriptional and physiological levels. We hypothesize that inflammasome derived IL-18 and PGE2 will act on the intestinal epithelium resulting in transcriptional reprogramming that promotes tissue regeneration and barrier reinforcement. Methods WT and Nlrc4-/- mSIOs were stimulated with flagellin or FlaTox to activate the NAIP-NLRC4 inflammasome. The transcriptomic landscape was assessed with bulk-RNA sequencing and inflammasome activation was assessed by Western blot. IL-18 and PGE2 dependent gene targets were identified using Il-18-/- and indomethacin treated mSIOs by RT-qPCR. Results Bulk-RNA sequencing revealed an inflammasome activation dependent transcriptional signature in murine IECs upon NAIP-NLRC4 inflammasome activation. GO term analysis showed these genes to be involved in actin cytoskeleton rearrangement, epidermal growth factor signaling, and regulation of cell-cell adhesion. The expression of PGE2 gene targets were significantly reduced by indomethacin treatment while IL-18 gene targets remained unaffected in Il-18-/- IECs. FlaTox induced the same transcriptional changes but substantially amplified their expression. FlaTox but not flagellin led to a significant drop in Lgr5 (stem cells) and Lyz1 (Paneth cell) expression and an increase in Ly6a, a marker of fetal-like stem cells. Conclusions This data demonstrates that inflammasome signaling causes transcriptional reprogramming of IECs that activates pathways involved in maintaining epithelial barrier integrity. While IL-18 had no effects on gene expression at 4 hours, PGE2 paracrine signaling contributed to the expression of wound healing genes. Stronger inflammasome mediated damage with FlaTox amplified the repair response at the transcript level and we observed transient reprogramming of IECs into a fetal-like state suggesting active tissue regeneration. Funding Agencies CCC, CIHREPIC: Emerging &amp; Pandemic Infections Consortium

LGR5 as a Therapeutic Target of Antibody-Functionalized Biomimetic Magnetoliposomes for Colon Cancer Therapy.

The lack of specificity of conventional chemotherapy is one of the main difficulties to be solved in cancer therapy. Biomimetic magnetoliposomes are successful chemotherapy controlled-release systems, hyperthermia, and active targeting agents by functionalization of their surface with monoclonal antibodies. The membrane receptor Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) stands out as colorectal cancer (CRC) biomarker and appears to be related to treatment resistance and the development of metastasis. The aim of this study was to assess the effectiveness and safety of LGR5-targeted biomimetic magnetoliposomes loaded with oxaliplatin (OXA) or 5-fluorouracil (5-FU) in the selective treatment of CRC and their possible application in hyperthermia. Synthesis, characterization and determination of heating capacity of magnetoliposomes transporting OXA or 5-FU (with and without LGR5 functionalization) were conducted. In vitro antitumoral activity was assayed in multiple colorectal cell lines at different times of exposition. In addition to this, cell internalization was studied by Prussian Blue staining, flow cytometry and fluorescence microscopy. In vivo acute toxicity of magnetoliposomes was performed to evaluate iron-related toxicity. OXA and 5-FU loaded magnetoliposomes functionalized with LGR5 antibody showed higher cellular uptake than non-targeted nanoformulation with a reduction of the percentage of proliferation in colon cancer cell lines up to 3.2-fold of the IC50 value compared to that of free drug. The differences between non-targeted and targeted nanoformulations were more evident after short exposure times (4 and 8 hours). Interestingly, assays in the MC38 transduced cells with reduced LGR5 expression (MC38-L(-)), showed lower cell internalization of LGR5-targeted magnetoliposomes compared to non-transduced MC38 cell line. In addition, magnetoliposomes showed an in vitro favorable heating response under magnetic excitation and great iron-related biocompatibility data in vivo. Drug-loaded magnetoliposomes functionalized with anti-LGR5 antibodies could be a promising CRC treatment strategy for LGR5+ targeted chemotherapy, magnetic hyperthermia, and both in combination.

Epigenetic characterization of sarcopenia-associated genes based on machine learning and network screening

To screen characteristic genes related to sarcopenia by bioinformatics and machine learning, and to verify the accuracy of characteristic genes in the diagnosis of sarcopenia. Download myopia-related data sets from geo public database, find the differential genes through R language limma package after merging, STRING database to build protein interaction network, and do Go analysis and GSEA analysis to understand the functions and molecular signal pathways that may be affected by the differential genes. Further screen the characteristic genes through LASSO and SVM-RFE machine algorithms, make the ROC curve of the characteristic genes, and obtain the AUC value. 10 differential genes were obtained from the data set, including 7 upregulated genes and 3 downregulated genes. Eight characteristic genes were screened by a machine learning algorithm, and the AUC value of characteristic genes exceeded 0.7. In patients with sarcopenia, the expression of TPPP3, C1QA, LGR5, MYH8, and CDKN1A genes are upregulated, and the expression of SLC38A1, SERPINA5, and HOXB2 genes are downregulated. The above genes have high accuracy in the diagnosis of sarcopenia. The research results provide new ideas for the diagnosis and mechanism research of sarcopenia.

Abstract C098: Targeting high-expression LGR5 by an R-spondin-based peptibody-drug conjugate is efficacious against neuroblastoma

Abstract Neuroblastoma (NB) is a pediatric tumor that predominantly affects infants and young children, with high-risk (HR) disease being diagnosed in approximately 50% of patients at 18 months or older. LGR4-6 are membrane receptors that bind RSPO ligands, activating Wnt signaling. LGR5, specifically expressed in adult stem cells, is highly upregulated in gastrointestinal (GI) cancers. In NB, high LGR5 expression is associated with aggressive disease and poor outcomes. Knockdown of LGR5 reduces cell growth in LGR5-high NB cell lines. The R-spondin-LGR5 axis has emerged as a potential therapeutic target due to its involvement in stem cell proliferation and self-renewal, as well as its overexpression in certain cancers, including neuroblastoma. RSPO-based peptibody drug conjugate (PDC) is a promising approach to target LGR4/5 for HR-NB therapy. PDCs are designed to selectively deliver the potent Pyrrolobenzodiazepine (PBD) dimer SG3199 to LGR5 high-expressing neuroblastoma cells using a peptibody that mimics the R-spondin binding activity of LGR5 ligands. Our preclinical study showed the efficacy of DAR2 R-spondin-based PDCs, generated through microbial transglutaminase-mediated site-specific conjugation, inducing cell death both in vitro and in vivo. Furthermore, these PDCs demonstrate reduced tumor growth and improved survival in xenograft animal models of neuroblastoma derived from the SK-N-AS cell lines. Our findings suggest that targeting LGR5 with RSPO2-based PDCs may offer a promising potential for treating neuroblastoma. Citation Format: Yukimatsu Toh. Targeting high-expression LGR5 by an R-spondin-based peptibody-drug conjugate is efficacious against neuroblastoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C098.

The oncogenic role of LGR6 overexpression induced by aberrant Wnt/β-catenin signaling in lung cancer.

Molecular abnormalities in the Wnt/β-catenin pathway confer malignant phenotypes in lung cancer. Previously, we identified the association of leucine-rich repeat-containing G protein-coupled receptor 6 (LGR6) with oncogenic Wnt signaling, and its downregulation upon β-catenin knockdown in non-small cell lung cancer (NSCLC) cells carrying CTNNB1 mutations. The aim of this study was to explore the mechanisms underlying this association and the accompanying phenotypes. LGR6 expression in lung cancer cell lines and surgical specimens was analyzed using quantitative RT-PCR and immunohistochemistry. Cell growth was assessed using colony formation assay. Additionally, mRNA sequencing was performed to compare the expression profiles of cells subjected to different treatments. LGR6 was overexpressed in small cell lung cancer (SCLC) and NSCLC cell lines, including the CTNNB1-mutated NSCLC cell lines HCC15 and A427. In both cell lines, LGR6 knockdown inhibited cell growth. LGR6 expression was upregulated in spheroids compared to adherent cultures of A427 cells, suggesting that LGR6 participates in the acquisition of cancer stem cell properties. Immunohistochemical analysis of lung cancer specimens revealed that the LGR6 protein was predominantly overexpressed in SCLCs, large cell neuroendocrine carcinomas, and lung adenocarcinomas, wherein LGR6 overexpression was associated with vascular invasion, the wild-type EGFR genotype, and an unfavorable prognosis. Integrated mRNA sequencing analysis of HCC15 and A427 cells with or without LGR6 knockdown revealed LGR6-related pathways and genes associated with cancer development and stemness properties. Our findings highlight the oncogenic roles of LGR6 overexpression induced by aberrant Wnt/β-catenin signaling in lung cancer.

LGR5 Expression Predicting Poor Prognosis Is Negatively Correlated with WNT5A in Colon Cancer.

WNT/β-catenin signaling is essential for colon cancer development and progression. WNT5A (ligand of non-canonical WNT signaling) and its mimicking peptide Foxy5 impair β-catenin signaling in colon cancer cells via unknown mechanisms. Therefore, we investigated whether and how WNT5A signaling affects two promoters of β-catenin signaling: the LGR5 receptor and its ligand RSPO3, as well as β-catenin activity and its target gene VEGFA. Protein and gene expression in colon cancer cohorts were analyzed by immunohistochemistry and qRT-PCR, respectively. Three colon cancer cell lines were used for in vitro and one cell line for in vivo experiments and results were analyzed by Western blotting, RT-PCR, clonogenic and sphere formation assays, immunofluorescence, and immunohistochemistry. Expression of WNT5A (a tumor suppressor) negatively correlated with that of LGR5/RSPO3 (tumor promoters) in colon cancer cohorts. Experimentally, WNT5A signaling suppressed β-catenin activity, LGR5, RSPO3, and VEGFA expression, and colony and spheroid formations. Since β-catenin signaling promotes colon cancer stemness, we explored how WNT5A expression is related to that of the cancer stem cell marker DCLK1. DCLK1 expression was negatively correlated with WNT5A expression in colon cancer cohorts and was experimentally reduced by WNT5A signaling. Thus, WNT5A and Foxy5 decrease LGR5/RSPO3 expression and β-catenin activity. This inhibits stemness and VEGFA expression, suggesting novel treatment strategies for the drug candidate Foxy5 in the handling of colon cancer patients.