Lgr5-positive Cells Research Articles

Rectal Epithelial Stem Cell Kinetics in Acute Radiation Proctitis

The intestinal tract is a typical radiosensitive tissue, and radiation rectal injury is a severe side effect that limits the prescribed dose in radiotherapy of the abdominal and pelvic region. Understanding the post-irradiation kinetics of Lgr5-positive stem cells is crucial in comprehending this adverse process. In this study, we utilized Lgr5-EGFP knock-in mice expressing EGFP and LGR5 antibody fluorescence staining of wild-type mice. At the state of radiation injury, the qPCR analysis showed a significant decrease in the expression level of Lgr5 in the rectal epithelial tissue. The dose-response relationship analysis showed that at low to moderate doses up to 10 gray (Gy), Lgr5-clustered populations were observed at the base of the crypt, whereas at sublethal doses (20 Gy and 29 Gy), the cells exhibited a dot-like scatter pattern, termed Lgr5-dotted populations. During recovery, 30 days post-irradiation, Lgr5-clustered populations gradually re-emerged while Lgr5-dotted populations declined, implying that some of the Lgr5-dotted stem cell populations re-clustered, aiding regenerations. Based on statistical analysis of the dose-response relationship using wild-type mice, the threshold dose for destroying these stem cell structures is 18 Gy. These findings may help set doses in mouse abdominal irradiation experiments for radiation intestinal injury and for understanding the histological process of injury development.

Anti-tumor activity of camptothecin analog conjugate of a RSPO4-based peptibody targeting LGR4/5/6 in preclinical models of colorectal cancer.

Antibody-drug conjugates (ADCs) have emerged as a major modality of targeted cancer therapy, yet no ADC has been approved for colorectal cancer (CRC). LGR4/5/6 (leucine-rich repeat containing, G protein-coupled receptor 4, 5, 6) are three related receptors that are expressed at high levels together or alternately in nearly all cases of CRC. ADCs targeting LGR5 have been shown to have robust anti-tumor potency, but not all CRC cells express LGR5 and LGR5-positive tumor cells may lose LGR5 expression due to cancer cell plasticity. R-spondin 4 (RSPO4) is a natural protein ligand of LGR4/5/6 with high affinity for all three receptors. We fused a mutant form of RSPO4 that retains high affinity binding to LGR4/5/6 to IgG1 Fc to create a peptibody designated R462. Conjugation of R462 with a camptothecin analog (CPT2) at eight drugs per peptibody led to the synthesis of R462-CPT2 that showed highly potent cytotoxic activity in vitro in CRC cell lines expressing any of LG4/5/6. In cell line xenograft and PDX models of CRC, R462-CPT2 demonstrated robust anti-tumor effect. Importantly, R462-CPT2 showed no major adverse effect at therapeutically effective dose levels. These results strongly support the use of RSPO ligand drug-conjugates that target LGR4/5/6 simultaneously for the treatment of CRC.

Exploring LGR5 as a prognostic marker of extrahepatic cholangiocarcinoma: insights from expression analysis and clinical correlations.

Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) is a cancer stem cell (CSC) marker of colorectal cancer and may be a CSC marker of other cancer types. Few studies have been conducted on LGR5 expression in extrahepatic cholangiocarcinoma (ECC). We analyzed LGR5 expression using RNAscope, a highly sensitive RNA in situ hybridization technique. Fifty-three ECCs were selected from the medical archives at Shinshu University Hospital and analyzed using a tissue microarray. LGR5 expression levels were divided into expression and no expression groups. LGR5 expression and clinicopathological characteristics were analyzed. Among 25 cases, no LGR5-positive dots were identified. Among 28 cases, some LGR5-positive dots were observed in carcinoma cells, together with a wide range of LGR5-positive cells. LGR5 expression was conspicuous in glandular duct formations. Well- to moderately differentiated types showed significantly higher LGR5 expression than the poorly differentiated type (p = 0.0268). LGR5 expression was associated with good overall survival (p = 0.0219) and good disease-free survival (DFS) (p = 0.0228). High LGR5 expression was associated with well- to moderately-differentiated types, indicating a favorable prognosis. In terms of DFS, multivariate analysis showed that high LGR5 expression was an independent favorable prognostic factor (p = 0.0397). These findings suggest that LGR5 is a promising, novel prognostic marker.

Leucine-rich repeat-containing G protein-coupled receptor 5 expression in lymph node metastases of colorectal cancer: Clinicopathological insights and prognostic implications.

Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5), a significant cancer stem cell marker in colorectal cancer (CRC), lacks lymph node (LN)expression studies. In this study, we identified LGR5 expression by RNAscope, a highly sensitive RNA in situ method, and analyzed its association with clinicopathological characteristics. Tissue microarrays were generated from primary tumors (PTs) and LN metastases in paraffin-embedded blocks of 38 CRC surgical resection materials. LGR5 expression by RNAscope was evaluated by dividing the expression levels into negative and positive expression. In all but two cases of LNmetastasis, LGR5-positive dots were detected in tumor cells, and there was a wide range of LGR5-positive cells. More LGR5-positive dots were identified in the gland-forming region. Twenty-three cases were classified into a high LGR5-expression group, and 15 cases were classified into a low LGR5-expression group. In the high LGR5-expression group, the histological grade was lower than in the low LGR5-expression group (p = 0.0159), while necrosis was significantly more prevalent (p = 0.0326), and the tumor, node, metastasis stage was significantly lower (p = 0.0302). There was no association between LGR5 expression levels in LN metastases and LGR5 expression levels in PT tissue. LGR5 expression in LN metastases may influence prognosis. Further analysis may lead to new therapeutic strategies.

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 >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 >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.

Direct Reprogramming of Hepatocytes Into JAK/Stat-Dependent LGR5+ Liver Cells Able to Initiate Intrahepatic Cholangiocarcinoma.

Somatic cells that have been partially reprogrammed by the factors Oct4, Sox2, Klf4, and cMyc (OSKM) have been demonstrated to be potentially tumorigenic in vitro and in vivo due to the acquisition of cancer-associated genomic alterations and the absence of OSKM clearance over time. In the present study, we obtained partially reprogrammed, SSEA1-negative cells by transducing murine hepatocytes with Δ1Δ3-deleted adenoviruses that expressed the 4 OSKM factors. We observed that, under long-term 2D and 3D culture conditions, hepatocytes could be converted into LGR5-positive cells with self-renewal capacity that was dependent on 3 cross-signaling pathways: IL6/Jak/Stat3, LGR5/R-spondin, and Wnt/β-catenin. Following engraftment in syngeneic mice, LGR5-positive cells that expressed the cancer markers CD51, CD166, and CD73 were capable of forming invasive and metastatic tumors reminiscent of intrahepatic cholangiocarcinoma (ICC): they were positive for CK19 and CK7, featured associations of cord-like structures, and contained cuboidal and atypical cells with dissimilar degrees of pleomorphism and mitosis. The LGR5+-derived tumors exhibited a highly vascularized stroma with substantial fibrosis. In addition, we identified pro-angiogenic factors and signaling pathways involved in neo-angiogenesis and vascular development, which represent potential new targets for anti-angiogenic strategies to overcome tumor resistance to current ICC treatments.

Mesenchymal Stem Cells Accelerate Recovery of Acetic Acid-Induced Chronic Gastric Ulcer by Regulating Ekt/Akt/TRIM29 Axis.

Chronic gastric ulcer (CGU), a prevalent digestive disease, has a high incidence and is seriously harmful to human health. Mesenchymal stem cells (MSCs) have been proven to have beneficial therapeutic effects in many human diseases. Here, a CGU model induced by acetic acid in mice was used to evaluate the repair effects and potential mechanism of human umbilical cord-derived MSCs (hUC-MSCs) and hUC-MSCs derived conditioned medium (hUC-MSC-CM). We found that hUC-MSCs and hUC-MSC-CM treatment significantly repaired morphological characteristics of CGU, improved proliferation and decreased apoptosis of gastric cells, and promoted the generation of new blood vessels in granulation tissues. In addition, we could detect the homing of MSCs in gastric tissue, and MSCs may differentiate into Lgr5-positive cells. As well as this, in vitro experiments showed that hUC-MSC-CM could promote cell proliferation, stimulate cell cycle progression, and reduce the incidence of apoptosis. The transcriptome of cells and the iTRAQ proteome of gastric tissues suggest that MSCs may play a therapeutic role by increasing the expression of TRIM29. Additionally, it was found that knocking down TRIM29 significantly decreased the ameliorative effects of hUC-MSC-CM on cell apoptosis. As a result of further molecular experiments, it was found that TRIM29 is capable of phosphorylating Erk/Akt in specific cell type. As a whole, it appears that hUC-MSCs can be an effective therapeutic approach for promoting gastric ulcer healing and may exert therapeutic effects in the form of paracrine and differentiation into gastric cells.

Cooperation of Wnt/β-catenin and Dll1-mediated Notch pathway in Lgr5-positive intestinal stem cells regulates the mucosal injury and repair in DSS-induced colitis mice model.

Lgr5-positive cells located in the basal layer of crypts have self-regenerative and proliferative differentiation potentials of intestinal stem cells (ISCs), maintaining a balance of regeneration-repair in mucosal epithelium. However, the mechanisms of mucosal repair that are regulated by ISCs in ulcerative colitis (UC) remain unclear. Colon tissues from patients with UC were collected to test β-catenin and Notch1 expression by using Western blot and quantitative real-time polymerase chain reaction (PCR). β-cateninfl/fl mice, β-cateninTg mice, and Dll1tm1 Gos mice were used to cross with Lgr5-EGFP-IRES-creERT2 mice to generate mice of different genotypes, altering the activation of Wnt/β-catenin and Dll1-mediated Notch signaling in ISCs in vivo. Dextran sulfate sodium (DSS) was used to induce a colitis mice model. Intestinal organoids were isolated and cultured to observe the proliferation and differentiation levels of ISCs. β-catenin and Notch1 expression were significantly increased in the inflamed colon tissues from patients with UC. Wnt/β-catenin activation and Dll1-mediated Notch pathway inhibition in Lgr5-positive stem cells promoted the expressions of E-cadherin, CK20, and CHGA in colonic organoids and epithelium, implying the promotion of colonic epithelial integrity. Activation of Wnt/β-catenin and suppression of Dll1-mediated Notch pathway in Lgr5-positive ISCs alleviated the DSS-induced intestinal mucosal inflammation in mice. Lgr5-positive ISCs are characterized by self-renewal and high dividend potential, which play an important role in the injury and repair of intestinal mucosa. More importantly, the Wnt/β-catenin signaling pathway cooperates with the Notch signaling pathway to maintain the function of the Lgr5-positive ISCs.

Mesenchymal Stem Cell-Derived Exosomes are Effective for Radiation Enteritis and Essential for the Proliferation and Differentiation of Lgr5+ Intestinal Epithelial Stem Cells by Regulating Mir-195/Akt/β-Catenin Pathway.

Radiation enteritis (RE) is a common complication of abdominal or pelvic radiotherapy, which when severe, could be life-threatening. Currently, there are no effective treatments. Studies have shown that mesenchymal stem cells (MSCs)-derived exosomes (MSC-exos) exhibit promising therapeutic effects in inflammatory diseases. However, the specific role of MSC-exos in RE and the regulatory mechanisms remain elusive. In vivo assay was carried out by injecting MSC-exos into the total abdominal irradiation (TAI)-induced RE mouse model. For in vitro assay, Lgr5-positive intestinal epithelial stem cells (Lgr5+ IESC) were extracted from mice, followed by irradiation along with MSC-exos treatment. HE staining was performed to measure histopathological changes. mRNA expression of inflammatory factors TNF-α and IL-6 and stem cell markers LGR5, and OCT4 were quantified by RT-qPCR. EdU and TUNEL staining was performed to estimate cell proliferation and apoptosis. MiR-195 expression in TAI mice and radiation-induced Lgr5+ IESC was tested. We found that the injection of MSC-exos inhibited inflammatory reaction, increased stem cell marker expression, and maintained intestinal epithelial integrity in TAI mice. Furthermore, MSC-exos treatment increased the proliferation and simultaneously suppressed apoptosis in radiation-stimulated Lgr5+ IESC. MiR-195 expression increased by radiation exposure was decreased by MSC-exos therapy. MiR-195 overexpression facilitated the progress of RE by counteracting the effect of MSC-exos. Mechanistically, the Akt and Wnt/β-catenin pathways inhibited by MSC-exos were activated by miR-195 upregulation. MSC-Exos are effective in treating RE and are essential for the proliferation and differentiation of Lgr5+ IESCs. Moreover, MSC-exos mediates its function by regulating miR-195 Akt β-catenin pathways.

Abstract 24: Oncogenic KrasG12D and Cdkn2a/p16 knockout in LGR5 expressing progenitor cells synergize to advance adenoma and adenocarcinoma phenotypes in murine small intestine

Abstract Background: KRAS activating mutations are reported in 42-54% and inactivation of CDKN2A/p16 in 14-30% of human small intestinal adenocarcinomas, suggesting a role in small intestine adenocarcinogenesis. The phenotypic effects of oncogenic KRAS and p16 loss have not been well characterized in small intestine (SI) adenocarcinogenesis. We targeted LGR5-expressing progenitor cells residing in intestinal crypts for conditional activation of Kras and/or Cdkn2a/p16 deletion to generate a murine model to study the single and combined effects of KRAS and p16 alterations driving gastrointestinal tumorigenesis. We hypothesized that oncogenic Kras and loss of Cdkn2a/p16 drives adenoma-adenocarcinoma sequence in murine SI. Methods: We generated mice with conditional knockout of Cdkn2a/p16 (p16del: IL1bwt/tg;Lgr5-Cre+/−;p16fl/fl;Kraswt/wt), conditional expression of oncogenic KrasG12D (IL1bwt/tg;Lgr5-Cre+/−;KrasG12D/wt), or both alterations (p16del+KrasG12D: IL1bwt/tg;Lgr5-Cre+/−;p16fl/fl;KrasG12D/wt), in mice carrying the human interleukin 1 beta (IL1B) and expressing modified Cre under the Lgr5 promoter. Our control murine model expresses wild type p16 and KRAS (p16wt+Kraswt: IL1bwt/tg;Lgr5-Cre+/−;p16wt/wt;Kraswt/wt). These mice were initially generated to study esophageal adenocarcinogenesis and express the IL1b transgene in esophagus but not in SI. All mice were given bile acid in drinking water daily and were treated with tamoxifen to activate Cre in Lgr5-positive gastrointestinal epithelial progenitor cells. Mice were euthanized and gross and histologic alterations in the SI were examined from 4 to 21 months of age. 3D organoids were isolated from the SI of each mouse model. Results: We examined 89 mice from 4 to 12 months of age. Mice with KRAS activation (KrasG12D) alone infrequently developed SI duodenal adenomas (6.25%: 1/16) compared to 50% (9/18) of mice carrying the combined P16del+KrasG12D genotypes (P=0.005). No adenomas were seen in 27 control and 28 p16del mice. Adenomas with high-grade dysplasia, intramucosal adenocarcinoma, and invasive adenocarcinoma were seen only in older p16del+KrasG12D mice (13-21 months). Single or multiple adenomas and adenocarcinomas were observed only in the duodenal segment of SI and not in the colon. 3D organoids isolated from each mouse model reproduce the intestinal histologic phenotype. Conclusions: Loss of Cdkn2a/p16 and KRASG12D expression synergistically advances adenoma-adenocarcinoma tumorigenesis in the SI duodenum, providing a murine model that recapitulates SI adenocarcinogenesis in vivo. 3D SI organoids provide useful in vitro models for mechanistic studies of SI adenocarcinogenesis. These in vivo and in vitro models will enable identification of key molecular pathways that may be targeted with novel therapies for this rare cancer. Citation Format: Tyler Seckar, Jing Sun, Elena V. Komissarova, Jorge L. Sepulveda, Timothy L. Wang, Antonia R. Sepulveda. Oncogenic KrasG12D and Cdkn2a/p16 knockout in LGR5 expressing progenitor cells synergize to advance adenoma and adenocarcinoma phenotypes in murine small intestine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 24.

RSPO3 Furin domain-conjugated liposomes for selective drug delivery to LGR5-high cells.

The transmembrane receptor LGR5 potentiates Wnt/β-catenin signaling by binding both secreted R-spondin (RSPOs) and the Wnt tumor suppressors RNF43/ZNRF3, directing clearance of RNF43/ZNRF3 from the cell surface. Besides being widely used as a stem cell marker in various tissues, LGR5 is overexpressed in many types of malignancies, including colorectal cancer. Its expression characterizes a subpopulation of cancer cells that play a crucial role in tumor initiation, progression and cancer relapse, known as cancer stem cells (CSCs). For this reason, ongoing efforts are aimed at eradicating LGR5-positive CSCs. Here, we engineered liposomes decorated with different RSPO proteins to specifically detect and target LGR5-positive cells. Using fluorescence-loaded liposomes, we show that conjugation of full-length RSPO1 to the liposomal surface mediates aspecific, LGR5-independent cellular uptake, largely mediated by heparan sulfate proteoglycan binding. By contrast, liposomes decorated only with the Furin (FuFu) domains of RSPO3 are taken up by cells in a highly specific, LGR5-dependent manner. Moreover, encapsulating doxorubicin in FuFuRSPO3 liposomes allowed us to selectively inhibit the growth of LGR5-high cells. Thus, FuFuRSPO3-coated liposomes allow for the selective detection and ablation of LGR5-high cells, providing a potential drug delivery system for LGR5-targeted anti-cancer strategies.

Age-related glomerular histogenesis in inbred indigenous rabbit (Oryctolagus cuniculus): A morphological, morphometrical, and immunohistochemical study with emphasis on Lgr5-positive cells

Although the regeneration of renal glomeruli and nephrons after injuries especially in adult mammals is not possible, understanding normal glomerular histogenesis is important. Here, we sought to study the morphometrical and histological development of the normal renal glomeruli of rabbits from birth until postnatal day 40. Moreover, we immunohistochemically evaluated the extent and rate of the Lgr5 expression in the immature renal stem/progenitor cells. The untreated, clinically healthy inbred indigenous rabbits (from Duhok city of Iraqi Kurdistan) were sacrificed at postnatal days 1, 10, 15, 30, and 40. After being processed and embedded in paraffin, rabbit anti-human Lgr5 as a primary antibody and rabbit ImmunoCruz LSAB as a staining kit were used for the immunohistochemical detection of Lgr5+ve cells. For normal histology, hematoxylin and eosin were used. The peak generation and regression of renal corpuscles were at postnatal days 10, and 40, respectively, with 50% decrease. The glomeruli diameter significantly increased (1.3-fold, p = 0.001), whereas the Bowman’s space diameter decreased (50%, p < 0.0001) from postnatal day 1–40. The immature nephrons were seen only in one-day postnatal rabbits. While the superficial glomeruli were compact and small, the juxtamedullary glomeruli were larger and segmented. The formation and development of the juxtaglomerular apparatus were documented at postnatal days 30 and 40 only. Our data revealed highly expressed Lgr5 protein at postnatal day one, and the expression level decreased gradually with advancing age. It was moderately expressed on day 10 and mildly expressed on day 15, whereas no expression was recorded on days 30 and 40 postnatally. Our study provides evidence that the Lgr5 gene, within multipotent stem cells and their lineage progeny, was activated within newly formed glomeruli throughout the early postnatal stages of nephrogenesis.

Morphology dynamics in intestinal crypt during postnatal development affect age-dependent susceptibility to radiation-induced intestinal tumorigenesis in ApcMin/+ mice: possible mechanisms of radiation tumorigenesis.

Age at exposure is a major modifier of radiation-induced carcinogenesis. We used mouse models to elucidate the mechanism underlying age-related susceptibility to radiation-induced tumorigenesis. Radiation exposure in infants was effective at inducing tumors in B6/B6-Chr18MSM-F1 ApcMin/+ mice. Loss of heterozygosity analysis revealed that interstitial deletion may be considered a radiation signature in this model and tumor number containing a deletion correlated with the susceptibility to radiation-induced tumorigenesis as a function of age. Furthermore, in Lgr5-eGFP-ires-CreERT2; Apcflox/flox mice, deletions of both floxed Apc alleles in Lgr5-positive stem cells in infants resulted in the formation of more tumors than in adults. These results suggest that tumorigenicity of Apc-deficient stem cells varies with age and is higher in infant mice. Three-dimensional immunostaining analyses indicated that the crypt architecture in the intestine of infants was immature and different from that in adults concerning crypt size and the number of stem cells and Paneth cells per crypt. Interestingly, the frequency of crypt fission correlated with the susceptibility to radiation-induced tumorigenesis as a function of age. During crypt fission, the percentage of crypts with lysozyme-positive mature Paneth cells was lower in infants than that in adults, whereas no difference in the behavior of stem cells or Paneth cells was observed regardless of age. These data suggest that morphological dynamics in intestinal crypts affect age-dependent susceptibility to radiation-induced tumorigenesis; oncogenic mutations in infant stem cells resulting from radiation exposure may acquire an increased proliferative potential for tumor induction compared with that in adults.

Expression of 5-HT Relates to Stem Cell Marker LGR5 in Patients with Gastritis and Gastric Cancer

Background5-Hydroxytryptamine (5-HT) and stem cells marker G-protein-coupled receptor 5 (LGR5) are associate with gastrointestinal inflammation and tumorigenesis. But the relationship between 5-HT and LGR5 is unclear.ObjectiveTo explore the expression and correlation of 5-HT and LGR5 in gastric mucosa of patients with gastritis and gastric cancer (GC).MethodsA total of 41 patients with GC and 98 patients with chronic gastritis were included in this study. The expression of TPH1 mRNA, LGR5 mRNA and β-catenin mRNA in gastric mucosa were explored by Real-time Quantitative polymerase chain reaction (qPCR). 5-HT-positive cells and LGR5-positive cells in gastric mucosa were detected by immunohistochemistry stains. The co-localization of 5-HT and chromogranin A (CgA), 5-HT receptor4 (5-HTR4) and LGR5 were detected by multiplex immunofluorescence.ResultsThe expression of 5-HT and LGR5 in patients with GC was significantly higher than patients with chronic gastritis (p < 0.05). The positive rate of 5-HT and LGR5 increased sequentially in the patients with non-atrophic gastritis, intestinal metaplasia and GC, which were 18.52%, 35.56% and 75.61% for 5-HT, and 27.78%, 40.91% and 95.12% for LGR5, respectively. The expression of 5-HT and LGR5 was positively correlated in gastritis and GC patients (p < 0.05). Moreover, the expression level of TPH1 mRNA and LGR5 mRNA was also positively correlated in gastritis patients (r = 0.7377, p < 0.001). Besides, 5-HT was partially co-localized with CgA, and 5-HTR4 was co-localized with LGR5 in gastric mucosa.ConclusionThe increase of 5-HT synthesis in gastric mucosa may have an impact on LGR5-positive gastric epithelial stem cells.

Serotonin Activity Is Correlated with Intestinal Stem Cell Proliferation in Small Intestinal Crypts

INTRODUCTION: Increased serotonin activity enhances small intestinal (SI) mucosal growth and nutrient absorption, but the mechanism behind this observation is unknown. This study evaluated the effect of serotonin signaling on intestinal stem cell (ISC) number and proliferation in mouse SI crypts. We hypothesized that alterations in serotonin activity correspond to changes in ISC proliferation. METHODS: Lgr5-EGFP-reporter mice were administered intraperitoneal citalopram, a selective serotonin reuptake inhibitor (SSRI), to potentiate serotonin activity, or para-chlorophenylalanine (PCPA), to inhibit serotonin synthesis. Control animals received saline alone. After 14 days, mice were injected intraperitoneally with bromodeoxyuridine (BrdU) to label actively dividing cells, followed by SI harvest 1 hour later. Immunofluorescence staining and microscopy identified Lgr5-positive ISC and BrdU-positive proliferating cells in epithelial crypts. ISC proliferation was quantified by calculating the proportion of crypts per animal with ≥1 cell expressing Lgr5 and labeled with BrdU. RESULTS: Compared with controls, SSRI treatment was associated with more Lgr5-positive cells per crypt (4.8 ± 0.9 vs 3.1 ± 0.6 cells/crypt; p < 0.01), and PCPA treatment resulted in no difference (3.5 ± 1.3 vs 3.1 ± 0.6 cells/crypt; p = 0.11); 66.6% of crypts in control animals did not contain proliferating stem cells. SSRI treatment was associated with a greater number of crypts exhibiting ISC proliferation (60.0% vs 33.3%; p < 0.01), and PCPA treatment was associated with fewer crypts containing proliferating ISCs (16.7% vs 33.3%; p < 0.01) compared with controls (Figure).FigureCONCLUSION: Serotonin activity is directly correlated with ISC proliferation in SI crypts. Modulation of stem cell activity with SSRIs may have therapeutic potential in patients who undergo SI resection.

Role of LGR5-positive mesenchymal cells in craniofacial development.

Leucine Rich Repeat Containing G Protein-Coupled Receptor 5 (LGR5), a Wnt pathway member, has been previously recognised as a stem cell marker in numerous epithelial tissues. In this study, we used Lgr5-EGFP-CreERT2 mice to analyse the distribution of LGR5-positive cells during craniofacial development. LGR5 expressing cells were primarily located in the mesenchyme adjacent to the craniofacial epithelial structures undergoing folding, such as the nasopharyngeal duct, lingual groove, and vomeronasal organ. To follow the fate of LGR5-positive cells, we performed lineage tracing using an inducible Cre knock-in allele in combination with Rosa26-tdTomato reporter mice. The slight expansion of LGR5-positive cells was found around the vomeronasal organ, in the nasal cavity, and around the epithelium in the lingual groove. However, most LGR5 expressing cells remained in their original location, possibly supporting their signalling function for adjacent epithelium rather than exerting their role as progenitor cells for the craniofacial structures. Moreover, Lgr5 knockout mice displayed distinct defects in LGR5-positive areas, especially in the reduction of the nasopharyngeal duct, the alteration of the palatal shelves shape, abnormal epithelial folding in the lingual groove area, and the disruption of salivary gland development. The latter defect manifested as an atypical number and localisation of the glandular ducts. The gene expression of several Wnt pathway members (Rspo1-3, Axin2) was altered in Lgr5-deficient animals. However, the difference was not found in sorted EGFP-positive cells obtained from Lgr5 +/+ and Lgr5 −/− animals. Expression profiling of LGR5-positive cells revealed the expression of several markers of mesenchymal cells, antagonists, as well as agonists, of Wnt signalling, and molecules associated with the basal membrane. Therefore, LGR5-positive cells in the craniofacial area represent a very specific population of mesenchymal cells adjacent to the epithelium undergoing folding or groove formation. Our results indicate a possible novel role of LGR5 in the regulation of morphogenetic processes during the formation of complex epithelial structures in the craniofacial areas, a role which is not related to the stem cell properties of LGR5-positive cells as was previously defined for various epithelial tissues.

Cytotoxic effect of disulfiram/copper on human cervical cancer cell lines and LGR5-positive cancer stem-like cells

BackgroundTumor resistance is a global challenge for tumor treatment. Cancer stem cells (CSCs) are the main population of tumor cells for drug resistance. We have reported that high aldehyde dehydrogenase (ALDH) activity represents a functional marker for cervical CSCs. Here, we aimed at disulfiram (DSF), an ALDH inhibitor, that has the potential to be used for cervical cancer treatment.MethodsMTT assay, western blot, vector construction and transfection, cell sorting and in vivo anti-tumor assays were performed using cervical cancer cell lines SiHa and HeLa. Cell cycle distribution and cell apoptosis were carried out by flow cytometry. The cytotoxicity of DSF was detected by MTT assay and cervical cancer xenograft models.ResultsDSF was cytotoxic to cervical cancer cell lines in a copper (Cu)-dependent manner. Disulfiram/copper (DSF/Cu) complex induced deregulation of S-phase and inhibited the expression of stemness markers in cervical cancer cells. Furthermore, DSF/Cu could also reduce the cancer stem cell-like LGR5+ cells which lead to cisplatin resistance in cervical cancer cells. DSF/Cu complex had the greater antitumor efficacy on cervical cancer than cisplatin in vitro and in vivo.ConclusionOur findings indicate that the cytotoxicity of DSF/Cu complex may be superior to cisplatin because of targeting LGR5-positive cervical cancer stem-like cells in cervical cancer. Thus, the DSF/Cu complex may represent a potential therapeutic strategy for cervical cancer patients.

Aging of intestinal stem cells.

SummaryThe intestine is one of the organs that relies on stem cell function for maintaining tissue homeostasis. Recent findings on intestinal aging show that intestinal architecture, such as villus length, crypt size, and cell composition changes in the aged crypts. The correspondent decline in the regenerative capacity of the intestine is mainly due to a decline in intestinal stem cell function upon aging, as the underlying mechanisms of aging intestinal stem cells are beginning to unravel. This review summarizes our current knowledge on stem cell-intrinsic mechanisms of aging of intestinal stem cells and their connection to extrinsic factors, such as niche cells and microbiota and will introduce recent approaches to attenuate or even revert the aging of intestinal stem cells.

P002 Glial cell line-Derived Neurotrophic Factor (GDNF) improves intestinal wound healing – A new target for IBD treatment?

Abstract Background Due to the rising incidence and socioeconomic relevance of Inflammatory Bowel Disease (IBD) worldwide, new therapeutic strategies are necessary to improve patient care. Since immunosuppressants are partially insufficient with relevant rates of side effects, novel concepts of treatment need to be developed. Mucosal and/or histological healing represent potential criteria to measure disease activity and are mentioned in current guidelines as favorable prognostic factors regarding disease outcomes. In previous studies, the soluble factor Glial cell line-Derived Neurotrophic Factor (GDNF) has been shown to be significantly reduced in tissue specimens from IBD patients and to be critically involved in intestinal epithelial barrier maturation. Therefore, the goal of this study was to further analyze the potential role of GDNF in IBD. Methods Intestinal wound healing was assessed in endoscopic biopsy-based wound assays as well as dextran sodium sulphate (DSS)-induced colitis in vivo. During the experiments, C57Bl/6 mice were either injected with GDNF or sodium chloride intraperitoneal while tissue samples were used for detailed molecular analyses. Further, scratch wound assays were performed in Caco2 monolayers to identify molecular pathways and cell mechanisms in vitro. Results Intraperitoneal injection of GDNF resulted in significantly enhanced wound closure in vivo. During the DSS-induced colitis model, mice treated with GDNF demonstrated significantly improved recovery from colitis in comparison to mice injected with sodium chloride. Similarly, application of GDNF in a scratch wound assay significantly enhanced wound closure in vitro. Mechanistically, molecular analysis revealed that GDNF application resulted in significantly increased cell proliferation. The effect of GDNF on cell proliferation was based on upregulation of LGR5-positive cells with increased phosphorylation of pSrc. Further studies demonstrated that the effect of GDNF on wound healing and cell proliferation could be inhibited by application of a Src-inhibitor. Conclusion GDNF significantly improves intestinal mucosal healing in vivo and in vitro which results in significantly enhanced recovery from colitis. While this effect is driven by increased cell proliferation due to upregulation of LGR5-positive cells and increased phosphorylation of pSrc, previous studies already demonstrated the critical impact of GDNF on epithelial barrier function. Following that, GDNF might have great potential in IBD treatment and could be a new target for future therapeutic approaches.

Olfactomedin 4 Is Not a Precise Marker for Human Intestinal Stem Cells, But Is Involved in Intestinal Carcinogenesis

Olfactomedin 4 Is Not a Precise Marker for Human Intestinal Stem Cells, But Is Involved in Intestinal Carcinogenesis