Leucine-rich repeat-containing G-protein-coupled receptor 5 is associated with invasion, metastasis, and could be a potential therapeutic target in human gastric cancer

Clinical Implications and Prognostic Value of Leucine-Rich G Protein-Coupled Receptor 5 Expression as A Cancer Stem Cell Marker in Malignancies: A Systematic Review and Meta-Analysis

Leucine-rich G protein-coupled receptor 5 (LGR5) is a marker of cancer stem cells (CSCs) in various cancers. Based on different studies, conflicting reports exist on correlation between LGR5 expression and poor prognosis/ clinicopathological parameters in cancer patients. Therefore, our purpose in conducting this study was to investigate correlation between LGR5 expression and outcomes of cancer patients under study through a systematic review and meta-analysis. Relevant articles were searched and collected using EMBASE, PubMed, Science Direct, and Scopus databases until December 21, 2022. This study was conducted to examine correlation between LGR5 expression and different clinical outcomes, such as recurrence-free survival (RFS), disease-free survival (DFS), overall survival (OS), and clinicopathological characteristics of the included cancer patients. To achieve this, hazard ratios (HRs) with 95% confidence intervals (CIs) and odds ratios (ORs) with 95% CIs were used as statistical measures. A meta-analysis was conducted using STATA 12.0 software. Finally, 53 studies including 9523 patients met the inclusion criteria. Significantly, high-level expression of LGR5 was related to poor prognosis in terms of OS, higher tumor stage, presence of distant metastasis, and presence of lymph node metastasis. It was discovered through subgroup analysis that several factors, including the study area, evaluation method, and type of cancer, can influence the correlation between LGR5 expression and negative prognosis in cancer patients. According to the results of our study, LGR5 overexpression was related to poor OS in cancer patients. In addition, clinicopathological data indicated an unfavorable prognosis in cancer patients with high LGR5 expression. In conclusion, LGR5 may serve as a potential prognostic marker for predicting survival in certain cancer types.

miR-21 Targets ASPP2 to Inhibit Apoptosis via CHOP-Mediated Signaling in Helicobacter pylori-Infected Gastric Cancer Cells

Helicobacter pylori (H. pylori) infection affects cell survival pathways, including apoptosis and proliferation in host cells, and disruption of this balance is the key event in the development of H. pylori-induced gastric cancer (HPGC). H. pylori infection induces alterations in microRNAs expression that may be involved in GC development. Bioinformatic analysis showed that microRNA-21 (miR-21) is significantly upregulated in HPGC. Furthermore, quantitative proteomics and in silico prediction were employed to identify potential targets of miR-21. Following functional enrichment and clustered interaction network analyses, five candidates of miR-21 targets, PDCD4, ASPP2, DAXX, PIK3R1, and MAP3K1, were found across three functional clusters in association with cell death and survival, cellular movement, and cellular growth and proliferation. ASPP2 is inhibited by H. pylori-induced miR-21 overexpression. Moreover, ASPP2 levels are inversely correlated with miR-21 levels in HPGC tumor tissues. Thus, ASPP2 was identified as a miR-21 target in HPGC. Here, we observed that H. pylori-induced ASPP2 suppression enhances resistance to apoptosis in GC cells using apoptosis assays. Using protein interaction network and coimmunoprecipitation assay, we identified CHOP as a direct mediator of the ASPP2 proapoptotic activity in H. pylori-infected GC cells. Mechanistically, ASPP2 suppression promotes p300-mediated CHOP degradation, in turn inhibiting CHOP-mediated transcription of Noxa, Bak, and suppression of Bcl-2 to enact antiapoptosis in the GC cells after H. pylori infection. Clinicopathological analysis revealed correlations between decreased ASPP2 expression and higher HPGC risk and poor prognosis. In summary, the discovery of H. pylori-induced antiapoptosis via miR-21-mediated suppression of ASPP2/CHOP-mediated signaling provides a novel perspective for developing HPGC management and treatment.

Stem Cell Biomarkers and Tumorigenesis in Gastric Cancer

Stomach cancer has a high mortality, which is partially caused by an absence of suitable biomarkers to allow detection of the initiation stages of cancer progression. Thus, identification of critical biomarkers associated with gastric cancer (GC) is required to advance its clinical diagnoses and treatment. Recent studies using tracing models for lineage analysis of GC stem cells indicate that the cell fate decision of the gastric stem cells might be an important issue for stem cell plasticity. They include leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5⁺), Cholecystokinin receptor 2 (Cckr2⁺), and axis inhibition protein 2 (Axin2⁺) as the stem cell markers in the antrum, Trefoil Factor 2 (TFF2⁺), Mist1⁺ stem cells, and Troy+ chief cells in the corpus. By contrast, Estrogen receptor 1 (eR1), Leucine-rich repeats and immunoglobulin-like domains 1 (Lrig1), SRY (sex determining region Y)-box 2 (Sox2), and B lymphoma Mo-MLV insertion region 1 homolog (Bmi1) are rich in both the antrum and corpus regions. These markers might help to identify the cell-lineage identity and analyze the plasticity of each stem cell population. Thus, identification of marker genes for the development of GC and its environment is critical for the clinical application of cancer stem cells in the prevention of stomach cancers.

Identification and validation of LGR5-binding peptide for molecular imaging of gastric cancer

Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) is a stem cell marker in gastric cancer. In this study, we aimed to produce the LGR5-targeting peptide probe for the use of molecular imaging for gastric cancer. We used phage display libraries to produce a LGR5-specific peptide probe. This peptide was validated for targeting gastric cancer with in vitro and in vivo studies. This peptide was tagged with fluorescein isothiocyanate (FITC) and cyanine 5.5 (Cy5.5). We used two normal and three gastric cancer cell lines. Immunocytochemistry (ICC) and fluorescence-activated cell sorting (FACS) analysis were used to validate the target specificity of the peptide. After three rounds of bio-panning, we found a novel 7-mer peptides, IPQILSI (IPQ∗). FITC-conjugated IPQ∗ showed 2 to 10 times higher fluorescence in gastric cancer cells vs. control cells in ICC. This discrimination was consistently observed using Cy5.5-conjugated IPQ∗ in ICC. FACS analysis showed right shift of peak point in gastric cancers compared to the control cells. In the peritoneal metastasis animal model, we could find Cy5.5-conjugated IPQ∗ accumulated specifically to gastric tumors. In conclusion, IPQ∗ peptide showed a specific probe for gastric cancer diagnosis. This probe can be applied to theragnosis for gastric cancer diagnosis including peritoneal metastasis.

Antibody drug conjugates in gastrointestinal cancer: From lab to clinical development

The antibody-drug conjugates (ADCs) are one the fastest growing biotherapeutics in oncology and are still in their infancy in gastrointestinal (GI) cancer for clinical applications to improve patient survival. The ADC based approach is developed with tumor specific antigen, antibody carrying cytotoxic agents to precisely target and deliver chemotherapeutics at the tumor site. To date, 11 ADCs have been approved by US-FDA, and more than 80 are in the clinical development phase for different oncological indications. However, The ADCs based therapies in GI cancers are still far from having high-efficient clinical outcomes. The limited success of these ADCs and lessons learned from the past are now being used to develop a newer generation of ADC against GI cancers. In this review, we did a comprehensive assessment of the key components of ADCs, including tumor marker, antibody, cytotoxic payload, and linkage strategy, with a focus on technical improvement and some future trends in the pipeline for clinical translation. The various preclinical and clinical ADCs used in gastrointestinal malignancies, their target, composition and bioconjugation, along with preclinical and clinical outcomes, are discussed. The emphasis is also given to new generation ADCs employing novel mAb, payload, linker, and bioconjugation methods are also included.

Targeting Glioblastoma Stem Cells: A Review on Biomarkers, Signal Pathways and Targeted Therapy

Glioblastoma (GBM) remains the most lethal and common primary brain tumor, even after treatment with multiple therapies, such as surgical resection, chemotherapy, and radiation. Although great advances in medical development and improvements in therapeutic methods of GBM have led to a certain extension of the median survival time of patients, prognosis remains poor. The primary cause of its dismal outcomes is the high rate of tumor recurrence, which is closely related to its resistance to standard therapies. During the last decade, glioblastoma stem cells (GSCs) have been successfully isolated from GBM, and it has been demonstrated that these cells are likely to play an indispensable role in the formation, maintenance, and recurrence of GBM tumors, indicating that GSCs are a crucial target for treatment. Herein, we summarize the current knowledge regarding GSCs, their related signaling pathways, resistance mechanisms, crosstalk linking mechanisms, and microenvironment or niche. Subsequently, we present a framework of targeted therapy for GSCs based on direct strategies, including blockade of the pathways necessary to overcome resistance or prevent their function, promotion of GSC differentiation, virotherapy, and indirect strategies, including targeting the perivascular, hypoxic, and immune niches of the GSCs. In summary, targeting GSCs provides a tremendous opportunity for revolutionary approaches to improve the prognosis and therapy of GBM, despite a variety of challenges.

Comparison of metastatic castration-resistant prostate cancer in bone with other sites: clinical characteristics, molecular features and immune status

Metastatic castration-resistant prostate cancer (mCRPC) is the lethal stage and the leading cause of death in prostate cancer patients, among which bone metastasis is the most common site. Here in this article, we downloaded the gene expression data and clinical information from online dataset. We found that prostate cancer metastasis in bone is prone to have higher prostate-specific antigen (PSA) and longer time on first-line androgen receptor signaling inhibitors (ARSI). A total of 1,263 differentially expressed genes (DEGs) were identified and results of functional enrichment analysis indicated the enrichment in categories related to cell migration, cancer related pathways and metabolism. We identified the top 20 hub genes from the PPI network and analyzed the clinical characteristics correlated with these hub genes. Finally, we analyzed the immune cell abundance ratio of each sample in different groups. Our results reveal the different clinical characteristics, the immune cell infiltration pattern in different sites of mCRPC, and identify multiple critical related genes and pathways, which provides basis for individualized treatment.

LGR5 expression is associated with prognosis in poorly differentiated gastric adenocarcinoma

Background

Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is an important cancer stem cell marker in gastric cancer. However, no detailed studies are available on LGR5 expression in poorly differentiated gastric adenocarcinoma (PD-AC). Therefore, we investigated the relationship between LGR5 expression and clinicopathological data in PD-AC.

Methods

LGR5 mRNA expression levels were quantified in 41 PD-AC specimens using a highly sensitive RNAscope in situ hybridization technique. Epstein–Barr virus (EBV) infection was also detected by EBV in situ hybridization.

Results

LGR5 expression levels were measured in 38 of 41 PD-AC cases, and 17 cases were identified as LGR5 high. The frequency of EBV positivity tended to be higher in the LGR5-low group than in the LGR5-high group (P = 0.0764). Furthermore, the frequency of vascular invasion tended to be higher in the LGR5-high group than in the LGR5-low group (P = 0.0764). The overall survival of PD-AC patients in the LGR5-high group was significantly lower than in the LGR5-low group (log-rank test, P = 0.0108). The Cox proportional hazard regression model revealed that the LGR5-low group (HR = 0.29; 95% CI: 0.11–0.74; P = 0.01) showed independently better OS for PD-AC.

Conclusions

Quantifying the levels of LGR5 expression may facilitate defining prognosis in Japanese patients with PD-AC. Further study of LGR5 in this context is warranted.

Clinical and prognostic significances of cancer stem cell markers in gastric cancer patients: a systematic review and meta-analysis

Background

Gastric cancer (GC) is considered one of the most lethal malignancies worldwide, which is accompanied by a poor prognosis. Although reports regarding the importance of cancer stem cell (CSC) markers in gastric cancer progression have rapidly developed over the last few decades, their clinicopathological and prognostic values in gastric cancer still remain inconclusive. Therefore, the current meta-analysis aimed to quantitatively re-evaluate the association of CSC markers expression, overall and individually, with GC patients’ clinical and survival outcomes.

Methods

Literature databases including PubMed, Scopus, ISI Web of Science, and Embase were searched to identify the eligible articles. Hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were recorded or calculated to determine the relationships between CSC markers expression positivity and overall survival (OS), disease-free survival (DFS)/relapse-free survival (RFS), disease-specific survival (DSS)/ cancer-specific survival (CSS), and clinicopathological features.

Results

We initially retrieved 4,425 articles, of which a total of 66 articles with 89 studies were considered as eligible for this meta-analysis, comprising of 11,274 GC patients. Overall data analyses indicated that the overexpression of CSC markers is associated with TNM stage (OR = 2.19, 95% CI 1.84–2.61, P = 0.013), lymph node metastasis (OR = 1.76, 95% CI 1.54–2.02, P < 0.001), worse OS (HR = 1.65, 95% CI 1.54–1.77, P < 0.001), poor CSS/DSS (HR = 1.69, 95% CI 1.33–2.15, P < 0.001), and unfavorable DFS/RFS (HR = 2.35, 95% CI 1.90–2.89, P < 0.001) in GC patients. However, CSC markers expression was found to be slightly linked to tumor differentiation (OR = 1.25, 95% CI 1.01–1.55, P = 0.035). Sub-analysis demonstrated a significant positive relationship between most of the individual markers, specially Gli-1, Oct-4, CD44, CD44V6, and CD133, and clinical outcomes as well as the reduced survival, whereas overexpression of Lgr-5, Nanog, and sonic hedgehog (Shh) was not found to be related to the majority of clinical outcomes in GC patients.

Conclusion

The expression of CSC markers is mostly associated with worse outcomes in patients with GC, both overall and individual. The detection of a combined panel of CSC markers might be appropriate as a prognostic stratification marker to predict tumor aggressiveness and poor prognosis in patients with GC, which probably results in identifying novel potential targets for therapeutic approaches.

Wnt Signaling Shapes the Histologic Variation in Diffuse Gastric Cancer

BACKGROUND AND AIMS

Diffuse-type gastric cancer (GC) is currently subdivided into signet-ring cell carcinoma (SRCC) and non-SRCC, referred to as poorly cohesive carcinoma not otherwise specified (PCC-NOS). Although these subtypes are considered to be independent, they often coexist in the same tumors, raising a question of whether they clonally differ or not. To tackle this question, we established an experimental platform for human diffuse GC that enables accurate modeling of histologic subtypes.

METHODS

Seven patient-derived diffuse GC organoid lines were established, characterized by histopathologic analysis, in situ hybridization, and gene expression analysis. For genetic modeling of diffuse GC, we knocked out CDH1 and/or TP53 in human normal gastric organoids. Green fluorescent protein-labeled GC organoids were xenotransplanted into immune-deficient mice for in vivo assessment.

RESULTS

PCC-NOS organoids transformed into SRCC-like structures on removal of Wnt and R-spondin from the culture medium. This morphologic change paralleled downregulation of Wnt-target and gastric stem cell genes, including LGR5, and elevation of differentiation markers, such as KRT20 and MUCs. The association between Wnt target gene expression and histologic subtypes was confirmed in 3 patient-derived GC tissues. In vivo, single clone-derived organoids formed tumors that comprised 2 distinct histologic compartments, each corresponding to SRCC and PCC-NOS. The transition from PCC-NOS to SRCC histology reflected the abundance of surrounding R-spondin-expressing fibroblasts.

CONCLUSIONS

SRCC and PCC-NOS were clonally identical, and their morphology was regulated by extracellular Wnt and R-spondin expression. Our results decoded how genetic mutations and the tumor environment shape pathohistologic and biologic phenotypes in human diffuse GCs.

Role of doublecortin-like kinase 1 and leucine-rich repeat-containing G-protein-coupled receptor 5 in patients with stage II/III colorectal cancer: Cancer progression and prognosis

BACKGROUND

Cancer stem cells (CSCs) are a subpopulation of cancer cells with the potential of self-renewal and differentiation. CSCs play critical roles in tumorigenesis, recurrence, metastasis, radiation tolerance and chemoresistance.

AIM

To assess the expression patterns and clinical potential of doublecortin-like kinase 1 (DCLK1) and leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5), as prognostic CSC markers of colorectal cancer (CRC).

METHODS

The expression of DCLK1 and Lgr5 in CRC tissue sections from 92 patients was determined by immunohistochemistry. Each case was evaluated using a combined scoring method based on signal intensity staining (scored 0-3) and the proportion of positively stained cancer cells (scored 0-3). The final staining score was calculated as the intensity score multiplied by the proportion score. Low expression of DCLK1 and Lgr5 was defined as a score of 0-3; high expression of DCLK1 and Lgr5 was defined as a score of ≥ 4. Specimens were categorized as either high or low expression, and the correlation between the expression of DCLK1 or Lgr5 and clinicopathological factors was investigated.

RESULTS

DCLK1 and Lgr5 expression levels were significantly positively correlated. CRC patients with high DCLK1, Lgr5 and DCLK1/Lgr5 expressions had poorer progression-free survival and overall survival. Moreover, high expression of DCLK1 was an independent prognostic factor for recurrence and overall survival in patients with CRC by multivariate analysis (P = 0.026 and P = 0.049, respectively).

CONCLUSION

DCLK1 may be a potential CSC marker for the recurrence and survival of CRC patients.

Cancer Stem Cells-Origins and Biomarkers: Perspectives for Targeted Personalized Therapies

The use of biomarkers in diagnosis, therapy and prognosis has gained increasing interest over the last decades. In particular, the analysis of biomarkers in cancer patients within the pre- and post-therapeutic period is required to identify several types of cells, which carry a risk for a disease progression and subsequent post-therapeutic relapse. Cancer stem cells (CSCs) are a subpopulation of tumor cells that can drive tumor initiation and can cause relapses. At the time point of tumor initiation, CSCs originate from either differentiated cells or adult tissue resident stem cells. Due to their importance, several biomarkers that characterize CSCs have been identified and correlated to diagnosis, therapy and prognosis. However, CSCs have been shown to display a high plasticity, which changes their phenotypic and functional appearance. Such changes are induced by chemo- and radiotherapeutics as well as senescent tumor cells, which cause alterations in the tumor microenvironment. Induction of senescence causes tumor shrinkage by modulating an anti-tumorigenic environment in which tumor cells undergo growth arrest and immune cells are attracted. Besides these positive effects after therapy, senescence can also have negative effects displayed post-therapeutically. These unfavorable effects can directly promote cancer stemness by increasing CSC plasticity phenotypes, by activating stemness pathways in non-CSCs, as well as by promoting senescence escape and subsequent activation of stemness pathways. At the end, all these effects can lead to tumor relapse and metastasis. This review provides an overview of the most frequently used CSC markers and their implementation as biomarkers by focussing on deadliest solid (lung, stomach, liver, breast and colorectal cancers) and hematological (acute myeloid leukemia, chronic myeloid leukemia) cancers. Furthermore, it gives examples on how the CSC markers might be influenced by therapeutics, such as chemo- and radiotherapy, and the tumor microenvironment. It points out, that it is crucial to identify and monitor residual CSCs, senescent tumor cells, and the pro-tumorigenic senescence-associated secretory phenotype in a therapy follow-up using specific biomarkers. As a future perspective, a targeted immune-mediated strategy using chimeric antigen receptor based approaches for the removal of remaining chemotherapy-resistant cells as well as CSCs in a personalized therapeutic approach are discussed.

Which is the optimal management for locally advanced gastric cancer patients with TRG 0 and 1 after R0 resection?

Background

Neoadjuvant chemotherapy (NAC) followed by surgery currently offers promise as a strategy for patients with locally advanced gastric cancer (GC). However, there is limited evidence to guide treatment for TRG 0 and 1 patients with locally advanced GC after R0 resection. This study set out to explore the optimal management for TRG 0 and 1 patients with locally advanced GC after R0 resection.

Methods

The retrospective data of 154 TRG 0 and 1 patients with locally advanced GC following R0 resection who were treated between January 2012 and December 2018 were collected and analyzed. The Kaplan-Meier method was used to estimate the survival rate. Multivariate analysis was performed using the Cox proportional hazards model.

Results

The median follow-up was 34.1 (range, 6.6–90.9) months. Six patients (3.9%) were lost during follow-up. Of the 27 patients who experienced relapse, 12 died, including 2 patients who died of non-neoplastic causes. The 5-year recurrence-free survival (RFS) and 5-year overall survival (OS) were 71.6% (95% CI: 68.5–79.6) and 82.9% (95% CI: 76.9–86.1) for the whole cohort, respectively. Univariate analysis revealed that patients with carcinoembryonic antigen (CEA) <5.0 ng/ml after NAC (77.7% vs. 20.1%, P<0.001), distal gastrectomy (91.7% vs. 67.5%, P=0.046) had higher 5-year RFS. Meanwhile, combined resection (55.6% vs. 73.1%, P=0.042), major complications (42.7% vs. 80.50%, P<0.001), and lymph node metastasis (ypN+) (52.0% vs. 83.7%, P<0.001) had lower 5-year RFS. The multivariate analysis showed that CEA level after NAC (HR =2.876, 95% CI: 1.051–7.872, P=0.040), major complications (HR =2.432, 95% CI: 1.062–5.567, P=0.035), and lymph node metastasis (ypN+) (HR =3.183, 95% CI: 1.242–8.161, P=0.016) were independent prognostic factors.

Conclusions

TRG 0 and 1 patients with local GC after R0 resection following NAC had a good prognosis, especially patients with CEA <5.0 ng/mL after NAC, and those without major complications or lymph node metastasis. Monotherapy or no chemotherapy may offer options for treating TRG 0 and 1 patients without adverse prognostic factors.

Functional roles of E3 ubiquitin ligases in gastric cancer

To date, >650 E3 ubiquitin ligases have been described in humans, including >600 really interesting new genes (RINGs), 28 homologous to E6-associated protein C-terminus (HECTs) and several RING-in-between-RINGs. They are considered key regulators and therapeutic targets of many types of human cancers, including gastric cancer (GC). Among them, some RING and HECT E3 ligases are closely related to the proliferation, infiltration and prognosis of GC. During the past few years, abnormal expressions and functions of many E3 ligases have been identified in GC. However, the functional roles of E3 ligases in GC have not been fully elucidated. The present article focuses on the functional roles of E3 ligases related to the proteasome in GC. In this comprehensive review, the latest research progress on E3 ligases involved in GC and elaborate their structure, classification, functional roles and therapeutic value in GC was summarized. Finally, 30 E3 ligases that serve essential roles in regulating the development of GC were described. Some of these ligases may serve as oncogenes or tumor suppressors in GC, whereas the pathological mechanism of others needs further study; for example, constitutive photomorphogenic 1. In conclusion, the present review demonstrated that E3 ligases are crucial tumor regulatory factors and potential therapeutic targets in GC. Therefore, more studies should focus on the therapeutic targeting of E3 ligases in GC.

Expression of LGR5, FZD7, TROY, and MIST1 in Perioperatively Treated Gastric Carcinomas and Correlation with Therapy Response

The cancer stem cell model is considered as a putative cause of resistance to chemotherapy and disease recurrence in malignant tumors. In this study, we tested the hypothesis that the response to neoadjuvant/perioperative chemotherapy correlates with the expression of four different putative cancer stem cell markers of gastric cancer (GC), i.e., LGR5, FZD7, TROY, and MIST1. The expression of LGR5, FZD7, TROY, and MIST1 was assessed by immunohistochemistry in 119 perioperatively treated GCs including pretherapeutic biopsies, resected primary GCs, and corresponding nodal and distant metastases. All four markers were detected in our cohort with variable prevalence and histoanatomical distributions. Few tumor cells expressed TROY. LGR5, FZD7, and MIST1 were coexpressed in 41.2% and completely absent in 6.2%. The prevalence of LGR5- and FZD7-positive GCs was higher and of TROY-positive GCs lower in perioperatively treated GCs compared with treatment-naïve tumors. LGR5, FZD7, and MIST1 in the primary tumors correlated significantly with their expression in the corresponding lymph node metastasis. An increased expression of LGR5 in primary GC correlated significantly with tumor regression. The expression of MIST1 in lymph node metastases correlated significantly with the number of lymph node metastases as well as overall and tumor-specific survival. FZD7 did not correlate with any clinicopathological patient characteristic. Our study on clinical patient samples shows that GCs may coexpress independently different stem cell markers; that neoadjuvant/perioperative treatment of GC significantly impacts on the expression of stem cell markers, which cannot be predicted by the analysis of pretherapeutic biopsies; and that their expression and tumor biological effect are heterogeneous and have to be viewed as a function of histoanatomical distribution.

Development of Fluorogenic Substrates of α-l-Fucosidase Useful for Inhibitor Screening and Gene-expression Profiling

Inhibitors of human α-l-fucosidases, tissue α-l-fucosidase (tFuc), and plasma α-l-fucosidase reportedly play roles in multiple diseases, suggesting their therapeutic potential for gastric disease associated with Helicobacter pylori and fucosidosis. Terminal fucose linkages on glycoproteins and glycolipids are a natural substrate for both enzymes; however, there are currently no fluorogenic substrates allowing their cellular evaluation. Here, we described the development of novel three-color fluorogenic substrates for lysosome-localized tFuc that exhibited excellent specificity and sensitivity in three human cell lines. Additionally, we developed a cell-based high-throughput inhibitor screening system in a 96-well format and a cell-based inhibitory activity evaluation system in a 6-well format for tFuc inhibitors using this substrate, which allowed accurate quantification of the inhibition rate. Moreover, analysis of significant changes in gene expression resulting from 30% inhibition of tFuc in HeLa cells revealed potential roles in gastric disease.

Evaluation of a biomarker for the diagnosis of pancreas cancer using an animal model

Many approaches have been taken to identify new biomarkers of pancreatic ductal carcinoma (PDC). Since animal models can be sampled under controlled conditions, better standardization is possible compared with heterogeneous human studies. Transgenic rats with conditional activation of oncogenic RAS in pancreatic tissue develop PDC that closely resembles the biological and histopathological features of human PDC. Using this model, we evaluated the usefulness of leucine-rich α2-glycoprotein-1 (LRG-1) as a serum marker. In this study, we found that LRG-1 was overexpressed in rat PDC compared with normal pancreas tissue of the control rats. Serum levels of LRG-1 were also significantly higher in rats bearing PDC than in controls. Importantly, chronic pancreatitis in male Wistar Bonn/Kobori rats, which is a widely accepted as a model of chronic pancreatitis, did not cause serum levels of LRG-1 to become elevated. These results strongly support serum LRG-1 as a candidate biomarker for noninvasive diagnosis of PDC. Our models of pancreas cancer provide a useful strategy for evaluation of candidate markers applicable to human cancer.

Immunohistochemical Analysis of LGR5 and TROY Expression in Gastric Carcinogenesis Demonstrates an Inverse Trend

Background

Two of the Wnt signaling pathway target genes, tumor necrosis factor receptor family member (TROY) and leucine-rich G-protein coupled receptor (LGR5), are involved in the generation and maintenance of gastrointestinal epithelium. A negative modulatory role has recently been assigned to TROY, in this pathway. Here, we have examined their simultaneous expression in gastric carcinogenesis.

Methods

Tumor and paired adjacent tissues of intestinal-type gastric cancer (GC) patients (n = 30) were evaluated for LGR5 and TROY expression by immunohistochemistry. The combination of the percentage of positively¬ stained cells and the intensity of staining was defined as the composite score and compared between groups. The obtained findings were re-evaluated in a mouse model.

Results

TROY expression in the tumor tissue was significantly lower than that of the adjacent tissue (2.5 ± 0.9 vs. 3.3 ± 0.9, p = 0.004), which was coincident with higher LGR5 expression (3.6 ± 1.1 vs. 2.7 ± 0.9, p = 0.001). This observation was prominent at stages II/III of GC, leading to a statistically significant mean difference of expression between these two molecules (p = 0.005). In the H. pylori infected-mouse model, this inverse expression was observed in transition from early (8-16 w) to late (26-50 w) time points, post treatment (p = 0.002).

Conclusion

Our data demonstrates an inverse trend between TROY down-regulation and LGR5 up-regulation in GC tumors, as well as in response to H. pylori infection in mice. These findings support a potential negative modulatory role for TROY on LGR5 expression.

Depletion of death-associated protein-3 induces chemoresistance in gastric cancer cells through the β-catenin/LGR5/Bcl-2 axis

Previously, we demonstrated that death-associated protein-3 (DAP3) loss drives chemoresistance in gastric cancer cells. In the present study, we aimed to determine the underlying molecular mechanism. The effect of DAP3 silencing on β-catenin signaling was assessed. The direct mediator of DAP3 silencing-induced chemoresistance was identified. Depletion of DAP3 stimulates nuclear accumulation of β-catenin and enhances β-catenin-dependent transcriptional activity in gastric cancer cells. However, the protein kinase B , , extracellular regulated protein kinase and signal transducer and activator of transcription 3 signaling pathways remain unaffected by DAP3 loss. We found that the downstream target gene LGR5 (leucine-rich G-protein coupled receptor 5) is upregulated in DAP3-depleted gastric cancer cells. Moreover, knockdown of LGR5 resensitizes DAP3-depleted gastric cancer cells to 5-fluorouracil (5-FU) and oxaliplatin. We also observed that ectopic expression of LGR5 reduces apoptosis in gastric cancer cells on treatment with 5-FU and oxaliplatin, which is accompanied by prevention of caspase-3 cleavage. The antiapoptotic protein Bcl-2 is identified as a key mediator of LGR5-induced apoptosis resistance in gastric cancer cells. The present findings indicate that DAP3 deficiency-induced chemoresistance in gastric cancer is at least partially mediated through the β-catenin/LGR5/Bcl-2 axis. Targeting LGR5 may provide a novel strategy to overcome chemoresistance in DAP3-deficient gastric cancer cells.

LGR5 promotes tumorigenicity and invasion of glioblastoma stem-like cells and is a potential therapeutic target for a subset of glioblastoma patients

Glioblastoma (GBM) is the most common and lethal primary malignant brain tumor which lacks efficient treatment and predictive biomarkers. Expression of the epithelial stem cell marker Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) has been described in GBM, but its functional role has not been conclusively elucidated. Here, we have investigated the role of LGR5 in a large repository of patient-derived GBM stem cell (GSC) cultures. The consequences of LGR5 overexpression or depletion have been analyzed using in vitro and in vivo methods, which showed that, among those with highest LGR5 expression (LGR5^high ), there were two phenotypically distinct groups: one that was dependent on LGR5 for its malignant properties and another that was unaffected by changes in LGR5 expression. The LGR5-responding cultures could be identified by their significantly higher self-renewal capacity as measured by extreme limiting dilution assay (ELDA), and these LGR5^high -ELDA^high cultures were also significantly more malignant and invasive compared to the LGR5^high -ELDA^low cultures. This showed that LGR5 expression alone would not be a strict marker of LGR5 responsiveness. In a search for additional biomarkers, we identified LPAR4, CCND2, and OLIG2 that were significantly upregulated in LGR5-responsive GSC cultures, and we found that OLIG2 together with LGR5 were predictive of GSC radiation and drug response. Overall, we show that LGR5 regulates the malignant phenotype in a subset of patient-derived GSC cultures, which supports its potential as a predictive GBM biomarker. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Regulatory T Cells Promote Overexpression of Lgr5 on Gastric Cancer Cells via TGF-beta1 and Confer Poor Prognosis in Gastric Cancer

Background: The leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5) is considered a cancer stem cell marker, and is often overexpressed in tumors. The interaction between Lgr5 and the immune-related tumor microenvironment is not completely understood. The aim of this study was to examine the role of Lgr5 in the microenvironment of gastric cancer (GC), and to explore possible immunological mechanisms influencing Lgr5 expression that are governed by regulatory T cells. Methods: Lgr5 expression was examined in 180 GC tumors by immunohistochemistry, and in 80 pairs of GC tumors for analysis of Th1/Th2 cytokines by ELISA. In addition, SGC7901 cells were co-cultured with patient-derived Tregs, varying concentrations of TGF-β1, TGF-β1 neutralizing antibody, or TGF-β receptor inhibitor SB431542, and Lgr5 and β-catenin expression were examined by qRT-PCR and western blot. Results: In this study, an immunosuppressive microenvironment was associated with high Lgr5 expression in GC. Furthermore, Lgr5 expression was up-regulated in GC cells co-cultured with Tregs or treated with exogenous TGF-β1. This up-regulation was partially inhibited by the TGF-β1 neutralizing antibody, or TGF-β1 receptor antagonist SB431542. β-catenin was up-regulated with high Lgr5 expression induced by exogenous TGF-β1, and this up-regulation was inhibited by SB431542. An increased number of Tregs and high Lgr5 expression in GC tissues were significantly associated with low overall survival. Conclusion: Tregs promoted increased Lgr5 expression in GC cells via TGF-β1 and TGF-β1 signaling pathway, which may involve activation of the Wnt signaling pathway. High Lgr5 expression via TGF-β confer poor prognosis in gastric cancer.

LGR5, a novel functional glioma stem cell marker, promotes EMT by activating the Wnt/β-catenin pathway and predicts poor survival of glioma patients

Background

Tumor recurrence, the chief reason for poor prognosis of glioma, is largely attributed to glioma stem cells (GSCs) and epithelial-mesenchymal transition (EMT). However, the mechanisms among them remain unknown. Here, we determined whether leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5), known as a stem cell marker for colon cancer and gastric cancer, can serve as a novel GSC marker involved in EMT and a therapeutic target in glioma.

Methods

Stemness properties were examined in FACS-isolated LGR5⁺/LGR5⁻ cells. Reported stem cell markers, EMT and the Wnt/β-catenin pathway were examined in stable LGR5 knockdown or overexpressed GSCs by Western Blot. The treatment experiment was performed in an intracranial orthotopic xenograft model by knockdown of LGR5 or by using the Wnt/β-catenin pathway inhibitor Wnt-C59. LGR5 expression was determined in 268 glioma specimens by immunohistochemistry.

Results

LGR5⁺ cells possessed stronger stemness properties compared to LGR5⁻ cells. The expression of SOX2, Nanog, CD133, CD44, CD24 and EpCAM was modulated by LGR5. Both LGR5 knockdown and Wnt-C59 reduced tumor invasion and migration and blocked EMT by inhibiting the Wnt/β-catenin pathway in vitro and suppressed the intracranial orthotopic xenograft growth and prolonged the survival of xenograft mice in vivo. Moreover, LGR5 was positively correlated with Ki67, N-cadherin and WHO grade and negatively correlated with IDH1. Glioma patients with high expression of LGR5 showed significantly poorer prognosis.

Conclusions

LGR5 is a new functional GSC marker and prognostic indicator that can promote EMT by activating the Wnt/β-catenin pathway and would thus be a novel therapeutic target for glioma.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0864-6) contains supplementary material, which is available to authorized users.

Towards precision medicine: linking genetic and cellular heterogeneity in gastric cancer

Molecular and cellular heterogeneity are phenomena that are revolutionizing oncology research and becoming critical to the idea of personalized medicine. Recent comprehensive molecular profiling has identified molecular subtypes of gastric cancer (GC) and linked them to clinical information. Moreover, GC stem cells (gCSCs) have been identified and found to be responsible for GC initiation and progression, Helicobacter pylori oncogenic action and therapy resistance. Addressing molecular heterogeneity is critical for achieving an optimal therapeutic approach against GC as well as targeting gCSCs. In this review, we outline the implications of molecular and cellular heterogeneity in the treatment of GC and we summarize the clinical impact of the most important regulators of gCSCs.

Effects of Celastrus orbiculatus on Epithelial Mesenchymal Transition in Gastric Mucosal Epithelial Cells by Inhibiting Lgr5 Expression from Rats with Gastric Precancerous Lesions

The extract of Celastrus orbiculatus (COE) has been shown to possess anti-Helicobacter pylori (H. pylori) activity and anticancer effects in vitro and in vivo. However, the molecular mechanism by which COE on precancerous lesions of gastric cancer (PLGC) has not been fully elucidated so far. The purpose of this study is to evaluate the effect and mechanism of COE in the rat model of PLGC, after the rat model of PLGC was successfully constructed. The effects of COE in gastric mucosa of rats with PLGC were tested using routine pathology and a transmission electron microscope (TEM) analysis. The protein and mRNA expression levels of epithelial mesenchymal transition (EMT) markers (E-cadherin, N-cadherin and Vimentin) and leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) were detected adopting techniques of immunohistochemistry (IHC), real-time PCR (RT-PCR) and western blot assays. The body weight of PLGC rats was significantly higher in the COE group than that in the untreated group. The process of PLGC was significantly reversed after COE treatment, shown by observing the changes of histopathological morphology and ultrastructure. Gastric mucosal epithelial cells in COE high dose (COE-H) group showed significantly higher expression levels of E-cadherin, and lower expression levels of N-cadherin, Vimentin and Lgr5 than those of the untreated group. COE could suppress the spatial distribution of Lgr5[Formula: see text] cell changes in PLGC rats. These findings suggested that the therapeutic mechanisms of COE in treating PLGC might be related with its effects on reversing the EMT process and inhibiting Lgr5 expression.

Evaluation of Anti-LGR5 Antibodies by ImmunoPET for Imaging Colorectal Tumors and Development of Antibody-Drug Conjugates

Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) is highly expressed in colorectal tumors and marks colon cancer stem cells that drive tumor growth and metastasis. Recently, we showed that LGR5 is a promising target for antibody-drug conjugate (ADC) therapy. However, it is important to identify LGR5-positive tumors that would respond to ADC treatment. Prior to drug conjugation, we evaluated two different anti-LGR5 monoclonal antibodies (mAbs), 8F2 and 9G5, using ⁸⁹Zr-immunoPET to select the optimal mAb for ADC development and tumor imaging. Binding, specificity, and internalization were compared, and mAbs were prescreened as ADC candidates against colon cancer cells using secondary ADCs. Both mAbs demonstrated strong, specific binding in 293T-LGR5 cells but not 293T-vector cells. In DLD-1 colorectal cancer cells, which express high levels of LGR5, the mAbs rapidly internalized into lysosomes and promoted ADC-induced cytotoxicity, with 8F2 exhibiting slightly higher potency. No binding was detected in DLD-1-shLGR5 (LGR5 knockdown) cells. ⁸⁹Zr-DFO-LGR5 mAbs were generated and shown to retain high affinity and LGR5-dependent uptake in vitro. PET/CT imaging of DLD-1 tumors was performed 5 days postinjection of ⁸⁹Zr-DFO-LGR5 mAbs, and findings were consistent with biodistribution data, which showed significantly higher tumor uptake (%ID/g) for ⁸⁹Zr-DFO-8F2 (17.9 ± 2.2) compared to ⁸⁹Zr-DFO-9G5 (5.5 ± 1.2) and ⁸⁹Zr-DFO-IgG (3.8 ± 1.0). No significant uptake was observed in DLD-1-shLGR5 tumors. This study identifies 8F2 as the optimal candidate for ADC development and provides initial evidence that ⁸⁹Zr-DFO-LGR5 mAbs may be utilized to stratify tumors which would respond best to LGR5-targeted ADC therapy.

Opposite Effects of Two Human ATG10 Isoforms on Replication of a HCV Sub-genomic Replicon Are Mediated via Regulating Autophagy Flux in Zebrafish

Autophagy is a host mechanism for cellular homeostatic control. Intracellular stresses are symptoms of, and responses to, dysregulation of the physiological environment of the cell. Alternative gene transcription splicing is a mechanism potentially used by a host to respond to physiological or pathological challenges. Here, we aimed to confirm opposite effects of two isoforms of the human autophagy-related protein ATG10 on an HCV subgenomic replicon in zebrafish. A liver-specific HCV subreplicon model was established and exhibited several changes in gene expression typically induced by HCV infection, including overexpression of several HCV-dependent genes (argsyn, leugpcr, rasgbd, and scaf-2), as well as overexpression of several ER stress related genes (atf4, chop, atf6, and bip). Autophagy flux was blocked in the HCV model. Our results indicated that the replication of the HCV subreplicon was suppressed via a decrease in autophagosome formation caused by the autophagy inhibitor 3MA, but enhanced via dysfunction in the lysosomal degradation caused by another autophagy inhibitor CQ. Human ATG10, a canonical isoform in autophagy, facilitated the amplification of the HCV-subgenomic replicon via promoting autophagosome formation. ATG10S, a non-canonical short isoform of the ATG10 protein, promoted autophagy flux, leading to lysosomal degradation of the HCV-subgenomic replicon. Human ATG10S may therefore inhibit HCV replication, and may be an appropriate target for future antiviral drug screening.

Clinical significance of putative markers of cancer stem cells in gastric cancer: A retrospective cohort study

Cancer stem cells (CSCs) are thought as the source of tumor maintaining and many CSCs markers have been identified. Regarding the heterogeneity in gastric cancer (GC), TNM stage is not enough to accurately predict the prognosis. The aim of this study was to investigate the clinical significance of CSCs markers (Lgr5, Oct4, CD133, EpCAM, CD54 and Sox2) and establish a new model based on these markers to accurately predict prognosis of GC. We retrospectively enrolled 377 GC tissues from January 2006 to October 2012 to perform immunohistochemistry (IHC), and 93 pairs of GC tissues and corresponding adjacent normal gastric tissues to perform quantitative PCR (qPCR) from December 2011 to October 2012. The clinicopathological and follow-up characteristics were collected. In IHC, Oct4, CD133 and EpCAM were independently related to tumor progression, while Sox2 were associated with well or moderate differentiation (all p<0.05). Cox regression showed that Oct4-EpCAM was an independently prognostic factor, indicating that double low expression of Oct4-EpCAM group had significantly better prognosis than control group (p=0.035). Regarding qPCR, CD133 was an independent prognostic factor, showing that the prognosis of patients with CD133 high expression was significantly worse than that of patients with CD133 low expression (p<0.001). The prognostic prediction accuracy of nomogram based on Oct4-EpCAM expression in IHC was significantly better than TNM stage alone (p=0.003). Low expressions of Oct4-EpCAM in IHC and CD133 in qPCR were favorable prognostic factors in GC. The nomogram based on Oct4-EpCAM was valuable in prognostic prediction of GC patients.

Toward early detection of Helicobacter pylori-associated gastric cancer

BACKGROUND

Gastric cancer is typically diagnosed at a late stage, leading to poor prognoses. Helicobacter pylori is responsible for 70% of gastric cancers globally, and patients with this bacterial infection often present with early stages of the carcinogenic pathway such as inflammation or gastritis. Although many patients continue to progress to advanced-stage disease after antibacterial treatment, there are no follow-up screening protocols for patients with a history of H. pylori.

METHODS

Several biomarkers (Lgr5, CD133, CD44) become upregulated during gastric carcinogenesis. A logistic regression model is developed using clinical data from 59 patients at different stages of the carcinogenic pathway to identify the likelihood of being at an advanced stage of disease for all combinations of age, sex, and marker positivity. Using these likelihood distributions and the observed rate of marker positivity increase, time to high likelihood (probability >0.8) of advanced disease for individual patients is predicted.

RESULTS

A strong correlation between marker positivity and disease stage was found for all three markers. Disease stage was accurately classified by the respective regression models for more than 86% of retrospective patients. Highly patient-specific predictions of time to onset of dysplasia were made, allowing the classification of 17 patients initially diagnosed with intestinal metaplasia into high-, intermediate-, or low-risk categories.

CONCLUSIONS

We present an approach designed to integrate pathology, mathematics, and statistics for detection of the earliest precancerous, treatable lesion. Given the simplicity and robustness of the framework, such technique has the potential to guide personalized screening schedules to minimize the risk of undetected malignant transformation.

Integrated Molecular Characterization of the Lethal Pediatric Cancer Pancreatoblastoma

Pancreatoblastoma is a rare pediatric pancreatic malignancy for which the molecular pathogenesis is not understood. In this study, we report the findings of an integrated multiomics study of whole-exome and RNA sequencing as well as genome-wide copy number and methylation analyses of ten pancreatoblastoma cases. The pancreatoblastoma genome was characterized by a high frequency of aberrant activation of the Wnt signaling pathway, either via somatic mutations of CTNNB1 (90%) and copy-neutral loss of heterozygosity (CN-LOH) of APC (10%). In addition, imprinting dysregulation of IGF2 as a consequence of CN-LOH (80%), gain of paternal allele (10%), and gain of methylation (10%) was universally detected. At the transcriptome level, pancreatoblastoma exhibited an expression profile characteristic of early pancreas progenitor-like cells along with upregulation of the R-spondin/LGR5/RNF43 module. Our results offer a comprehensive description of the molecular basis for pancreatoblastoma and highlight rational therapeutic targets for its treatment.Significance: Molecular genetic analysis of a rare untreatable pediatric tumor reveals Wnt/IGF2 aberrations and features of early pancreas progenitor-like cells, suggesting cellular origins and rational strategies for therapeutic targeting. Cancer Res; 78(4); 865-76. ©2017 AACR.

Leucine-rich repeat-containing G protein-coupled receptor 5 and CD133 expression is associated with tumor progression and resistance to preoperative chemoradiotherapy in low rectal cancer

Preoperative chemoradiotherapy has been performed as a standard therapy for advanced low rectal cancer. Cancer stem cells (CSCs) have been reported to contribute to resistance to treatment and patient prognosis. Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) and cluster of differentiation (CD133) are putative markers for CSCs. However, their prognostic ability remains unknown, and evaluation of a single marker can be insufficient due to the heterogeneity of cancer. LGR5 and CD133 expression was immunohistochemically evaluated in surgical specimens of 56 patients who received curative resection following chemoradiotherapy for advanced low rectal cancer. In addition, the correlations between their expression levels, and clinicopathological features and patient prognosis were asessed. LGR5 expression was significantly correlated with lymphatic invasion, lymph node metastasis, and tumor node metastasic (TNM) stage. CD133 expression was significantly correlated with vascular invasion and the tumor regression grade. Combined expression was significantly correlated with lymphatic invasion, tumor regression grade and TNM stage, but not with overall, and disease-free survival. LGR5 and CD133 expressions may represent useful markers associated with tumor progression and resistance to chemoradiotherapy in patients with low rectal cancer. Furthermore, combined expression of these markers may be a more useful marker compared with the expression of each single marker.

FOXO1 reduces tumorsphere formation capacity and has crosstalk with LGR5 signaling in gastric cancer cells

Gastric cancer (GC) is a major of cause of cancer-related death and is characterized by its heterogeneity and molecular complexity. FOXO1 is a transcription factor that plays a key role in GC growth and metastasis. However, the implication of FOXO1 in GC cell stemness has been elusive. This study, for the first time, demonstrates that FOXO1 regulates GC cell stemness in association with LGR5. FOXO1 expression was significantly lower in GC tumorsphere cells than in adherent GC cells. FOXO1 silencing and overexpression promoted and inhibited the tumorsphere formation capacity of GC cells, respectively. Additionally, there was an inverse correlation between FOXO1 and GC stem cell marker LGR5 in human GC specimens. Further in vitro and in vivo experiments showed that negative crosstalk between these two molecules exists and that LGR5 silencing reversed the FOXO1 shRNA-induced tumorsphere formation even without FOXO1 restoration. Taken together, our results suggest that FOXO1 inhibits the self-renewal capacity of GC cells through interaction with LGR5. Thus, FOXO1/LGR5 signaling pathway may provide a novel targeted therapy for GC.

Novel Insights into Gastric Cancer: Methylation of R-spondins and Regulation of LGR5 by SP1

Recently, it was shown that leucine-rich repeat-containing receptor 5 (LGR5)-expressing stem cells are the cellular origin of intestinal-type gastric cancer. The aim of our study was to uncover regulatory mechanisms of LGR5 expression in gastric mucosa and their implications for cancer development. Reporter assays identified an LGR5 promoter fragment, which is highly relevant for active LGR5 expression. Chromatin immunoprecipitation verified that SP1 is bound within this region, and reporter activity increased in SP1 transfected cells. Subsequently, the expression of R-spondins (RSPO1 and RSPO2), ligands of LGR5, was explored in neoplastic and nonneoplastic gastric tissue and gastric cancer cell lines. Using IHC, distinct spatial expression patterns of LGR5, RSPO1, and RSPO2 were found in nonneoplastic stomach mucosa and gastric cancer. RSPO expression was lower in gastric cancer compared with nonneoplastic mucosa on both the transcriptional (P = 0.003 for RSPO1 and P = 0.000 for RSPO2; n = 50) and the translational level. Methylation-specific PCR showed higher methylation levels of RSPO1/2 and reexpression of RSPOs in the gastric cancer cell lines MKN45 and MKN74 were induced by demethylating 5-aza-C treatment. Finally, expression patterns of LGR5 and RSPO were similar in gastric cancer.Implications: This report identifies a regulatory mechanism of LGR5 expression in gastric carcinogenesis, with SP1 as an important component of the transcriptional complex and LGR5 activity, which is modulated by its ligands RSPO1 and RSPO2, whose expression is modulated by methylation.Visual Overview: http://mcr.aacrjournals.org/content/15/6/776/F1.large.jpg. Mol Cancer Res; 15(6); 776-85. ©2017 AACR.

Ring finger protein 43 associates with gastric cancer progression and attenuates the stemness of gastric cancer stem-like cells via the Wnt-β/catenin signaling pathway

Background

Ring finger protein 43 (RNF43) is a member of the transmembrane E3 ubiquitin ligase family that was originally found in stem cells and plays important roles in tumor formation and progression. Our previous study indicated that RNF43 might be a tumor suppressor protein in gastric cancer. Given its antagonistic relationship with leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5), one of the gastric cancer stem cell markers, investigation of the potential role of RNF43 in gastric stem cancer cells is necessary.

Methods

Immunohistochemistry staining, western blot analysis, and quantitative reverse transcription polymerase chain reaction were used to determine the mRNA and protein expression level of RNF43 and other Wnt pathway factors. Gastric cancer stem-like cells were obtained from gastric cancer tumor and cell lines by tumorsphere culture. The adeno-associated virus system was used to upregulate RNF43 expression in cancer cells. Functional experiments including tumorsphere formation, chemotherapy resistance, surface marker detection, and tumor xenograft assay were performed to measure stem-like properties in gastric cancer stem-like cells after RNF43 overexpression.

Results

RNF43 loss was significantly associated with TNM stage, distant metastasis, and Lauren classification, and predicted worse prognosis in gastric cancer patients. RNF43 expression was even lower in tumorspheres derived from tumor tissues or cell lines compared with adherent cancer cells and normal gastric cells. Overexpression of RNF43 in gastric cancer cells impaired their stem-like properties, including sphere formation ability, chemoresistance in vitro, and tumorigenicity in vivo. Moreover, Wnt pathway-related proteins were decreased in RNF43-overexpressing cells, while Wnt pathway activators could reverse the trend to some extent.

Conclusions

Our findings indicated that RNF43 might not only participate in gastric cancer progression, but also attenuate the stemness of gastric cancer stem-like cells through the Wnt/β-catenin pathway.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0548-8) contains supplementary material, which is available to authorized users.

Distribution of Lgr5-positive cancer cells in intramucosal gastric signet-ring cell carcinoma

Leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) is a putative intestinal stem cell marker that is also expressed in various tumors. To analyze its pathological characteristics in mucosal gastric signet-ring cell carcinoma (SRCC), we investigated Lgr5 expression in 35 intramucosal gastric SRCC patients using RNAscope, a newly developed RNA in situ hybridization technique. Lgr5 expression in individual tumor cells was scored semi-quantitatively from 0 to 400. Ki67 was also examined by immunohistochemistry, with a linear arrangement of Ki67-expressing cells present in 20 of 35 cases. This area of Ki67-expressing cells was topographically divided into upper, middle, and lower regions. All cases with linear Ki67 expression patterns also had Lgr5-positive cells arranged in a linear fashion in the lower area-which was distinct from the area of high Ki67 expression. The rate of Ki67 positivity in Lgr5-positive cells was significantly lower than that of Lgr5-negative cells in areas of high Ki67 expression. In intramucosal SRCC, the low mitotic activity of Lgr5-positive cells suggests that they may represent cancer stem cells as seen in other types of stomach carcinomas. Intramucosal SRCC may therefore contain stem cells expressing Lgr5 in the lower area of the lamina propria, akin to normal gastric pyloric mucosa.

Gastric cancer stem cells: Signal pathways and targeted therapies

Gastric cancer is still one of the most common malignant neoplasms worldwide and the third leading cause of cancer-related death. Therefore, it is of great significance to clarify the mechanism of gastric cancer oncogenesis. In the past decades, the theory of cancer stem cell has enhanced our knowledge of gastric cancer. Cancer stem cells are defined as cells within a tumor that possess the capacity to self-renew and to cause the heterogeneous lineages of cancer cells that comprise the tumor. The dysregulation of certain signal pathways occurs during tumor formation. Recently, the research on gastric cancer stem cells (GCSCs) and related signal pathways has provided a new theoretical basis for clarifying the mechanism of gastric cancer and treating this malignancy. This review will discuss the role of related signal pathways in GCSCs and therapies targeting the key molecules of these pathways.

Prognostic significance of leucine-rich-repeat-containing G-protein-coupled receptor 5, an intestinal stem cell marker, in gastric carcinomas

BACKGROUND

Cells expressing LGR5, an intestinal stem cell marker, have been suggested as cancer stem cells in human colon cancers. Previously, we discovered that LGR5-expressing cells exist in the gastric antrum and remarkably increase in number in intestinal metaplasia. In addition, most gastric adenomas contain abundant LGR5-expressing cells coexpressing intestinal stem cell signatures. However, LGR5 expression in gastric cancers (GCs) and its prognostic significance remain unknown.

METHODS

We examined the LGR5 expression in GC tissues by real time-PCR and RNA in situ hybridization, and analyzed its clinicopathological relevance and prognostic value. The effects of LGR5 on cancer cell proliferation and migration were assessed with an in vitro transfection technique.

RESULTS

LGR5 expression was significantly lower in GCs than in matched nontumorous gastric mucosa. RNA in situ hybridization on tissue microarrays showed that 7 % of GCs were positive for LGR5. LGR5 positivity was associated with old age, well to moderate differentiation, and nuclear β-catenin positivity. Although LGR5 did not show any prognostic significance for all GC cases, it was associated with poor survival in GCs with nuclear β-catenin expression. LGR5 expression was induced by transfection in GC cell lines with abnormal Wnt activation, which, however, showed no influence on the growth and migration of GC cells.

CONCLUSION

A small portion of GCs expressed LGR5. Although LGR5 was associated with poor survival in GCs with nuclear β-catenin, LGR5 expression in GC cells had no effects on the growth and migration, requiring a further study exploring a biological role of LGR5 in GCs.

LGR5-Targeted Antibody-Drug Conjugate Eradicates Gastrointestinal Tumors and Prevents Recurrence

Gastrointestinal cancer is one of the leading causes of cancer-related mortality in men and women worldwide. The adult stem cell marker LGR5 (leucine-rich repeat-containing, G protein-coupled receptor 5) is highly expressed in a significant fraction of gastrointestinal tumors of the colon, liver, pancreas, and stomach, relative to normal tissues. LGR5 is located on the cell surface and undergoes rapid, constitutive internalization independent of ligand. Furthermore, LGR5-high cancer cells have been shown to exhibit the properties of tumor-initiating cells or cancer stem cells (CSC). On the basis of these attributes, we generated two LGR5-targeting antibody-drug conjugates (ADC) by tethering the tubulin-inhibiting cytotoxic drug monomethyl auristatin E to a highly specific anti-LGR5 mAb via a protease cleavable or noncleavable chemical linker and compared them in receptor binding, cell internalization, and cytotoxic efficacy in cancer cells. Here, we show that both ADCs bind LGR5 with high specificity and equivalent nanomolar affinity and rapidly internalize to the lysosomes of LGR5-expressing gastrointestinal cancer cells. The anti-LGR5 ADCs effectively induced cytotoxicity in LGR5-high gastrointestinal cancer cells, but not in LGR5-negative or -knockdown cancer cell lines. Overall, we demonstrate that the cleavable ADC exhibited higher potency in vitro and was able to eradicate tumors and prevent recurrence in a xenograft model of colon cancer. These findings provide preclinical evidence for the potential of LGR5-targeting ADCs as effective new therapeutics for the treatment and eradication of gastrointestinal tumors and CSCs with high LGR5 expression. Mol Cancer Ther; 15(7); 1580-90. ©2016 AACR.

Gastric Lgr5(+) stem cells are the cellular origin of invasive intestinal-type gastric cancer in mice

The cellular origin of gastric cancer remains elusive. Leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) is the first identified marker of gastric stem cells. However, the role of Lgr5(+) stem cells in driving malignant gastric cancer is not fully validated. Here, we deleted Smad4 and PTEN in murine gastric Lgr5(+) stem cells by the inducible Cre-LoxP system and marked mutant Lgr5(+) stem cells and their progeny with Cre-reporter Rosa26(tdTomato). Rapid onset and progression from microadenoma and macroscopic adenoma to invasive intestinal-type gastric cancer (IGC) were found in the gastric antrum with the loss of Smad4 and PTEN. In addition, invasive IGC developed at the murine gastro-forestomach junction, where a few Lgr5(+) stem cells reside. In contrast, Smad4 and PTEN deletions in differentiated cells, including antral parietal cells, pit cells and corpus Lgr5(+) chief cells, failed to initiate tumor growth. Furthermore, mutant Lgr5(+) cells were involved in IGC growth and progression. In the TCGA (The Cancer Genome Atlas) database, an increase in LGR5 expression was manifested in the human IGC that occurred at the gastric antrum and gastro-esophageal junction. In addition, the concurrent deletion of SMAD4 and PTEN, as well as their reduced expression and deregulated downstream pathways, were associated with human IGC. Thus, we demonstrated that gastric Lgr5(+) stem cells were cancer-initiating cells and might act as cancer-propagating cells to contribute to malignant progression.

The prognostic role of Leucine-rich repeat-containing G-protein-coupled receptor 5 in gastric cancer: A systematic review with meta-analysis

BACKGROUND AND OBJECTIVE

The prognostic value of Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) in gastric cancer remains controversial. To further investigate this relationship, we performed meta-analyses to systematically review the association between LGR5 expression and various clinical parameters in gastric cancer patients.

METHOD

Eligible studies from PubMed, Embase, Web of Science, CNKI (Chinese National Knowledge Infrastructure), Wangfang (Database of Chinese Ministry of Science & Technology) and CBM (China Biological Medicine) databases were evaluated to investigate the association of LGR5 expression with overall survival (OS) and clinicopathological features of gastric cancer.

RESULTS

LGR5 overexpression was significantly associated with poor OS in patients with gastric cancer (HR 1.66, 95% CI 1.02-2.69). LGR5 overexpression was also significantly associated with TNM stage (TIII/TIV vs TI/TII: OR 5.42, 95% CI 1.02-28.72) and lymph node metastasis (positive vs negative: OR 2.30, 95% CI 1.06-5.0).

CONCLUSIONS

Our meta-analysis indicates that LGR5 may be a predictive factor for invasion and metastasis, and poor prognosis in patients with gastric cancer.

Lgr5 expression, cancer stem cells and pancreatic cancer: results from biological and computational analyses

AIMS

To determine the relationship between Lgr5 and other stemness markers and pathologic features in pancreatic ductal adenocarcinoma (PDAC) samples.

MATERIALS & METHODS

In 69 samples, Lgr5 was analyzed by qRT-PCR together with a panel of 29 genes. Bioinformatic analysis was carried out to identify a possible pathway regulating Lgr5 expression in PDAC.

RESULTS

Lgr5 expression was not associated with the expression of tested cancer stem cell markers. Moreover, it was not an independent predictor of survival neither at univariate analysis (p = 0.21) nor at multivariate analysis (p = 0.225).

CONCLUSION

Based on the lack of correlation between Lgr5 and tested cancer stem cell markers, Lgr5 does not seem to be a potential stemness marker or prognostic factor in PDAC.

Pathobiology of Helicobacter pylori-Induced Gastric Cancer

Colonization of the human stomach by Helicobacter pylori and its role in causing gastric cancer is one of the richest examples of a complex relationship among human cells, microbes, and their environment. It is also a puzzle of enormous medical importance given the incidence and lethality of gastric cancer worldwide. We review recent findings that have changed how we view these relationships and affected the direction of gastric cancer research. For example, recent data have indicated that subtle mismatches between host and microbe genetic traits greatly affect the risk of gastric cancer. The ability of H pylori and its oncoprotein CagA to reprogram epithelial cells and activate properties of stemness show the sophisticated relationship between H pylori and progenitor cells in the gastric mucosa. The observation that cell-associated H pylori can colonize the gastric glands and directly affect precursor and stem cells supports these observations. The ability to mimic these interactions in human gastric organoid cultures as well as animal models will allow investigators to more fully unravel the extent of H pylori control on the renewing gastric epithelium. Finally, our realization that external environmental factors, such as dietary components and essential micronutrients, as well as the gastrointestinal microbiota, can change the balance between H pylori's activity as a commensal or a pathogen has provided direction to studies aimed at defining the full carcinogenic potential of this organism.

MicroRNAs as biomarkers and prospective therapeutic targets in colon and pancreatic cancers

Colon and pancreatic cancers have high mortality rates due to early metastasis prior to the onset of symptoms. Screening tests for colorectal cancer are invasive and expensive. No effective screening is available for pancreatic cancer. Identification of biomarkers for early detection in both of these cancers is being extensively researched. MicroRNAs (miRNA) are small non-coding molecule biomarkers that regulate cancers. Measurement of miRNAs in pancreatic fluid or blood could be a preferred non-invasive screening method. The regulation of colon and pancreatic cancers by miRNA is complex. miRNA play a central role in inflammation, invasiveness, and tumor progression in these two cancers, as well as regulation of the NF-κB pathway. miRNA's evolving role in screening is also reviewed.

G-protein coupled receptor 34 knockdown impairs the proliferation and migration of HGC-27 gastric cancer cells in vitro

Background:

Overexpression of G-protein coupled receptor 34 (GPR34) affects the progression and prognosis of human gastric adenocarcinoma, however, the role of GPR34 in gastric cancer development and progression has not been well-determined. The current study aimed to investigate the effect of GPR34 knockdown on the proliferation, migration, and apoptosis of HGC-27 gastric cancer cells and the underlying mechanisms.

Methods:

The expression of GPR34 in gastric cancer cell line HGC-27 was detected by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. HGC-27 cells were employed to construct the stable GPR34 knockdown cell model in this study. Real-time RT-PCR and Western blotting were applied to validate the effect of short hairpin RNA (ShRNA) on the expression of GPR34 in HGC-27 gastric cells. The proliferation, migration of these cells were examined by Cell Counting Kit-8 and transwell. We also measured expression profile of PI3K/PDK1/AKT and ERK using Western blotting.

Results:

The ShRNA directed against GPR34 effectively inhibited both endogenous mRNA and protein expression levels of GPR34, and significantly down-regulated the expression of PIK3CB (P < 0.01), PIK3CD (P < 0.01), PDK1 (P < 0.01), phosphorylation of PDK1 (P < 0.01), Akt (P < 0.01), and ERK (P < 0.01). Furthermore, GPR34 knockdown resulted in an obvious reduction in HGC-27 cancer cell proliferation and migration activity (P < 0.01).

Conclusions:

GPR34 knockdown impairs the proliferation and migration of HGC-27 gastric cancer cells in vitro and provides a potential implication for therapy of gastric cancer.

Lysine-specific demethylase 1 promotes the stemness and chemoresistance of Lgr5(+) liver cancer initiating cells by suppressing negative regulators of β-catenin signaling

Cancer initiating cells (CICs) are responsible for the unrestrained cell growth and chemoresistance of malignant tumors. Histone demethylation has been shown to be crucial for self-renewal/differentiation of stem cells, but it remains elusive whether lysine-specific demethylase 1 (LSD1) regulates the stemness properties of CICs. Here we report that the abundant expression of leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) is associated with the progression of hepatocellular carcinoma (HCC). Lgr5(+) HCC cells behave similarly to CICs and are highly tumorigenic and resistant to chemotherapeutic agents. Importantly, Lgr5(+) cells express higher levels of LSD1, which in turn regulates Lgr5 expression and promotes the self-renewal and drug resistance of Lgr5(+) CICs. Mechanistically, LSD1 promotes β-catenin activation by inhibiting the expression of several suppressors of β-catenin signaling, especially Prickle1 and APC in Lgr5(+) CICs, by directly regulating the levels of mono- and di-methylation of histone H3 lysine-4 at the promoters of these genes. Furthermore, LSD1-associated activation of the β-catenin signaling is essential for maintaining the activity of Lgr5(+) CICs. Together, our findings unravel the LSD1/Prickle1/APC/β-catenin signaling axis as a novel molecular circuit regulating the stemness and chemoresistance of hepatic Lgr5(+) CICs and provide potential targets to improve chemotherapeutic efficacies against HCC.

Characterization of LGR5 stem cells in colorectal adenomas and carcinomas

LGR5 is known to be a stem cell marker in the murine small intestine and colon, however the localization of LGR5 in human adenoma samples has not been examined in detail, and previous studies have been limited by the lack of specific antibodies. Here we used in situ hybridization to specifically examine LGR5 mRNA expression in a panel of human adenoma and carcinoma samples (n = 66). We found that a small number of cells express LGR5 at the base of normal colonic crypts. We then showed that conventional adenomas widely express high levels of LGR5, and there is no evidence of stereotypic cellular hierarchy. In contrast, serrated lesions display basal localization of LGR5, and the cellular hierarchy resembles that of a normal crypt. Moreover, ectopic crypts found in traditional serrated adenomas show basal LGR5 mRNA, indicating that they replicate the stem cell organization of normal crypts with the development of a cellular hierarchy. These data imply differences in the stem cell dynamics between the serrated and conventional pathways of colorectal carcinogenesis. Furthermore we noted high LGR5 expression in invading cells, with later development of a stem cell niche in adenocarcinomas of all stages.