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

Hepatotoxicity assessment of innovative nutritional supplements based on olive-oil formulations enriched with natural antioxidants

Introduction

This study focuses on the assessment of extra virgin olive-oil and olive fruit-based formulations enriched with natural antioxidants as potential nutritional supplements for alleviating symptoms and long-term consequences of illnesses whose molecular pathophysiology is affected by oxidative stress and inflammation, such as Alzheimer's disease (AD).

Methods

Besides evaluating cell viability and proliferation capacity of human hepatocellular carcinoma HepG2 cells exposed to formulations in culture, hepatotoxicity was also considered as an additional safety measure using quantitative real-time PCR on RNA samples isolated from the cell cultures and applying approaches of targeted molecular analysis to uncover potential pathway effects through gene expression profiling. Furthermore, the formulations investigated in this work contrast the addition of natural extract with chemical forms and evaluate the antioxidant delivery mode on cell toxicity.

Results

The results indicate minimal cellular toxicity and a significant beneficial impact on metabolic molecular pathways in HepG2 cell cultures, thus paving the way for innovative therapeutic strategies using olive-oil and antioxidants in dietary supplements to minimize the long-term effects of oxidative stress and inflammatory signals in individuals being suffered by disorders like AD.

Discussion

Overall, the experimental design and the data obtained support the notion of applying innovative molecular methodologies and research techniques to evidently advance the delivery, as well as the scientific impact and validation of nutritional supplements and dietary products to improve public health and healthcare outcomes.

Differential epithelial and stromal LGR5 expression in ovarian carcinogenesis

Lgr5 has been identified as a marker of the stem/progenitor cells in the murine ovary and oviduct by lineage tracing. However, little is known regarding LGR5 expression or its functional significance in human ovary tissues. Here, using RNA in situ hybridization and/or immunohistochemistry, we thoroughly investigated LGR5 expression in normal human ovaries, fallopian tubes and various ovarian tumors. We discovered that LGR5 expression is negligible in the human ovary surface epithelium, whereas ovarian stromal cells normally express low levels of LGR5. Remarkably, fallopian tube epithelium, inclusion cysts and serous cystadenomas with a Müllerian phenotype expressed high levels of LGR5, and LGR5 expression was restricted to PAX8⁺/FOXJ1^- secretory cells of the tubal epithelium. Strong stromal LGR5 expression without epithelial LGR5 expression was consistently observed in the path from serous cystadenoma to serous borderline tumor to low grade serous carcinoma (LGSC). Unlike LGSC, high grade serous carcinoma (HGSC), clear cell carcinoma, endometrioid carcinomas displayed various epithelial-stromal LGR5 expression. Notably, high levels of LGR5 expression were observed in serous tubal intraepithelial carcinoma, which slightly declined in invasive HGSC. LGR5 expression was significantly associated with improved progression-free survival in HGSC patients. Moreover, in vitro assays demonstrated that LGR5 expression suppressed tumor proliferation and migratory capabilities. Taken together, these findings indicate a tumor-suppressive role for LGR5 in the progression of HGSC.

Expression of LGR5 in mammary myoepithelial cells and in triple-negative breast cancers

Lineage tracing in mice indicates that LGR5 is an adult stem cell marker in multiple organs, such as the intestine, stomach, hair follicles, ovary, and mammary glands. Despite many studies exploring the presence of LGR5 cells in human tissues, little is known about its expression profile in either human mammary tissue or pathological lesions. In this study we aim to investigate LGR5 expression in normal, benign, and malignant lesions of the human breast using RNA in situ hybridization. LGR5 expression has not been observed in normal lactiferous ducts and terminal duct lobular units, whereas LGR5-positive cells have been specifically observed in the basal myoepithelium of ducts in the regenerative tissues, ductal carcinoma in situ, and in ducts surrounded by invasive cancer cells. These findings suggest LGR5 marks facultative stem cells that are involved in post injury regeneration instead of homeostatic stem cells. LGR5 positivity was found in 3% (9 of 278 cases) of invasive breast cancers (BC), and it showed positive associations with higher histologic grades (P = 0.001) and T stages (P < 0.001), while having negative correlations with estrogen receptor (P < 0.001) and progesterone receptor (P < 0.001) expression. Remarkably, all LGR5-positive BC, except one, belong to triple-negative BC (TNBC), representing 24% (9 of 38 cases) of all of them. LGR5 histoscores have no correlations with EGFR, CK5/6, Ki-67, or P53 expression. Additionally, no β-catenin nuclear localization was observed in LGR5-positive BC, indicating that canonical Wnt pathway activation is less likely involved in LGR5 expression in BC. Our results demonstrate that LGR5 expression is induced in regenerative conditions in the myoepithelium of human mammary ducts and that its expression is only observed in TNBC subtype among all invasive BC. Further studies regarding the functional and prognostic impact of LGR5 in TNBC are warranted.

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.

Lgr5 and stem/progenitor gene expression in gastric/gastroesophageal junction carcinoma - significance of potentially retained stemness

Background

Gastric/gastroesophageal junction (GEJ) adenocarcinomas are heterogeneous, comprising four molecularly distinct subtypes, namely EBV-positive, microsatellite instability (MSI), chromosomal instability (CIN) and genomically stable (GS) subtypes, and a part of this heterogeneity may hypothesized to be different cells-of-origin. Stem/progenitor cell hierarchy in the stomach is complex, which include the Lgr5⁽⁺⁾ gastric stem cells (GSCs).

Methods

While previous studies have focused on non-nuclear Lgr5 expression, nuclear Lgr5 expression has been reported in a subset of stem cells, and we examined nuclear Lgr5 expression in a local cohort of 95 cases of gastric/GEJ adenocarcinoma. mRNA levels for LGR5 and other stem cell marker genes were examined in the TCGA cohort.

Results

We observed nuclear Lgr5 expression in a 18/95 cases. Near mutual exclusivity was seen between nuclear Lgr5 and strong non-nuclear Lgr5. Both strong non-nuclear and nuclear Lgr5 expression tended to be seen more frequently with the intestinal histotype and approximated CIN molecular subtype. With respect to overall survival (OS), nuclear Lgr5 expression appears to be protective, with the worst survival being seen in the cases lacking nuclear Lgr5 and with low non-nuclear Lgr5 expression. When compared to other stem/progenitor cell markers, LGR5 mRNA expression clusters with other GSC marker genes, including VIL1. Higher expression of these GSC marker genes was associated with better OS.

Conclusions

Our results show that Lgr5 expression is dynamic in gastric/GEJ adenocarcinoma and heterogeneous across the several disease attributes. We postulate that this may reflect “retained stemness” in the form of Lgr5^High-GSC signature that appears to be associated with better survival.

Correlation of clinicopathological features and LGR5 expression in colon adenocarcinoma

Colon cancer stem cells (CSCs) are closely related to tumorigenesis and treatment response, and LGR5 is currently the most robust and reliable CSC marker in colorectal cancer (CRC). However, LGR5 expression in CRC tumor budding (TB) is not well understood. We examined the clinicopathological and prognostic significance of LGR5 in CRC TB. LGR5 expression was evaluated by RNAscope, a newly developed RNA in situ hybridization technique, using a tissue microarray consisting of 55 patient samples of TB in colon adenocarcinoma (CA) selected from the medical archives at our hospital. Patients were stratified into negative and positive LGR5 expression groups. Tumor-infiltrating lymphocytes (TILs) and histological grade were lower in the LGR5-positive group compared with the LGR5-negative group (P = .0407 and P = .0436, respectively). There was no significant difference in overall survival between the LGR5-positive group and the LGR5-negative group (log-rank test, P = .6931). LGR5 expression did not remain a predictor of prognosis in univariate analysis (OR = 0.84, 95% CI: 0.33-2.02, P = .6928). LGR5 expression may be affected by TILs, which have been demonstrated to be associated with worse prognosis in the budding area of CA and is an important potential marker of prognosis.

Correlation of Clinicopathological Features and LGR5 Expression in Triple-Negative Breast Cancer

LGR5 is the most robust known stem cell marker for gastrointestinal tumors, but there are few reports in breast cancer. Triple negative breast cancer (TNBC) is the most malignant subtype of breast cancer, and thus identification of new cancer stem cell populations in TNBC may help to identify targeted therapies. LGR5 expression was evaluated by RNAscope, a newly developed RNA in situ hybridization technique, using a tissue microarray consisting of 43 patient samples of TNBC selected from the medical archives at our hospital. Patients were stratified into negative and positive LGR5 expression groups. Tumor necrosis was greater in the LGR5-positive group compared with the LGR5-negative group (P = .026). Mitosis tended to show a high value in the LGR5-positive group compared with the LGR5-negative group (P = .0831), while stage tended to show a high stage in the LGR5-positive group compared with the LGR5-negative group (P = .0617). Cox proportional hazards models revealed that the LGR5-positive group (overall survival (OS) = 2.12; 95% CI: 2.12-2.12; P = 0.1575) had no relationship with OS. LGR5 expression is associated with tumor necrosis of TNBC and suggested higher malignant potential.

Clinical implications of cancer stem cells in digestive cancers: acquisition of stemness and prognostic impact

Digestive system cancers are the most frequent cancers worldwide and often associated with poor prognosis because of their invasive and metastatic characteristics. Recent studies have found that the plasticity of cancer cells can impart cancer stem-like properties via the epithelial-mesenchymal transition (EMT). Cancer stem-like properties such as tumor initiation are integral to the formation of metastasis, which is the main cause of poor prognosis. Numerous markers of cancer stem cells (CSCs) have been identified in many types of cancer. Therefore, CSCs, via their stem cell-like functions, may play an important role in prognosis after surgery. While several reports have described prognostic analysis using CSC markers, few reviews have summarized CSCs and their association with prognosis. Herein, we review the prognostic potential of eight CSC markers, CD133, CD44, CD90, ALDH1A1, EPCAM, SOX2, SOX9, and LGR5, in digestive cancers including those of the pancreas, colon, liver, gastric, and esophagus.

Correlation of clinicopathological features and leucine-rich repeat-containing G-protein-coupled receptor 5 expression in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common form of pancreatic cancer. Previous studies have established leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) as a cancer stem cell marker in gastrointestinal cancers. However, few reports have examined LGR5 in PDAC. Here we examined LGR5 expression and its clinicopathological significance in PDAC. We evaluated LGR5 expression in 78 PDAC patients who underwent surgical resection in our institution using RNAscope, a newly described RNA in situ hybridization technique. All 78 PDAC cases expressed LGR5 in cancer tissues, and LGR5 expression was prominent in the gland-forming part. LGR5 expression was significantly higher in patients with low histological grade (G1-G2) (p <  0.001) and early clinical stage (p =  0.004). Univariate analysis showed that low LGR5 expression (p =  0.034) was significantly associated with worse overall survival. However, LGR5 expression did not remain a predictor of prognosis in multivariate analysis (p =  0.639). All PDAC cases showed LGR5 expression to varying degrees, indicating LGR5 might be a cancer stem cell marker of PDAC, as in gastrointestinal cancer. Reduced LGR5 expression in tumor cells was associated with worse prognosis in PDAC. Further studies are required to elucidate the relationship between tumor progression and LGR5 expression in PDAC.

Correlation of clinicopathological features and LGR5 expression in colon adenocarcinoma

Colon cancer stem cells (CSCs) are closely related to tumorigenesis and treatment response, and LGR5 is currently the most robust and reliable CSC marker in colorectal cancer (CRC). However, LGR5 expression in CRC tumor budding (TB) is not well understood. We examined the clinicopathological and prognostic significance of LGR5 in CRC TB. LGR5 expression was evaluated by RNAscope, a newly developed RNA in situ hybridization technique, using a tissue microarray consisting of 55 patient samples of TB in colon adenocarcinoma (CA) selected from the medical archives at our hospital. Patients were stratified into negative and positive LGR5 expression groups. Inflammatory cell infiltration was weaker and histological grade was lower in the LGR5-positive group compared with the LGR5-negative group (P = 0.0407 and P = 0.0436, respectively). There was a significant difference in OS between the LGR5-positive group and LGR5-negative group (log-rank test, P = 0.0088). Cox proportional hazards models revealed that the LGR5-positive group (Overall survival (OS) = 0.37, 95% CI: 0.17-0.79, P = 0.0101) had better OS. LGR5 expression may be affected by inflammatory cell infiltration in the budding area of CA and is an important potential marker of prognosis.

Overexpression of cancer stem cell marker Lgr5 in colorectal cancer patients and association with clinicopathological findings

BACKGROUND

To determine the expression of cancer stem cell marker Leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5) in colorectal carcinoma samples compared to normal adjacent tissue and any possible association with clinicopathological findings.

METHODS

This study was performed on forty samples of cancerous colorectal tissues (case group) and their adjacent normal mucosa (control group) in Imam Khomeini Hospital (Sari, Mazandaran, Iran). Expression of Lgr5 in tissue sections was done by immunohistochemistry. Statistical analysis was carried out using SPSS software.

RESULTS

Forty colorectal cancer patients including 21 males (57.8±11.6 years) and 19 females (58.4±12.77 years) were enrolled. Lgr5 was overexpressed in tumoral samples than normal adjacent tissues (77.5% vs 27.5%, p<0.001). Also, no association was found between primary tumor, regional lymph nodes, invasion, histological type, grade, distant metastasis and IHC results. Patients with low Lgr5 expression had a better survival rate than patients with high expression but this was not statistically significant (p=0.121).

CONCLUSION

The higher immunoreactivity of Lgr5 in colorectal cancer tissues may indicate its role as a cancer stem cell marker in tumor carcinogenesis and patient's survival however; Lgr5 is not associated with pathological prognostic variables.

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.

Upregulation of miR-501-5p activates the wnt/β-catenin signaling pathway and enhances stem cell-like phenotype in gastric cancer

Background

miRNAs are critical post-transcriptional regulators of gene expression and key mediators of tumourigenesis. miR-501-5p is newly identified to be involved in the tumor progression, but its biological role and mechanism remain largely unknown. This study is aimed to study the role of miR-501-5p in the progression of gastric cancer.

Methods

Real-time PCR analysis was used to determine miR-501-5p expression in gastric cancer cell lines, clinical tissues and 112 clinicopathologically characterized gastric cancer specimens. The role of miR-501-5p in maintaining gastric cancer stem cell like phenotype was examined by tumor-sphere formation assay and expression of stem cell markers. Luciferase reporter assay, cellular fractionation and western blot analysis were used to determined that miR-501-5p activated the wnt/β-catenin signaling by directly targeting DKK1, NKD1 and GSK3β.

Results

Herein, our results revealed that miR-501-5p was markedly upregulated in gastric cancer cell lines and clinical tissues. High miR-501-5p levels predicted poor overall survival in gastric cancer patients. Gain-of-function and loss-of-function studies showed that ectopic expression of miR-501-5p enhanced the cancer stem cell-like phenotype in gastric cancer cells. Notably,wnt/β-catenin signaling was hyperactivated in gastric cancer cells that overexpress miR-501-5p, and mediated miR-501-5p-induced cancer stem cell-like phenotype. Furthermore, miR-501-5p directly targeted and suppressed multiple repressors of the wnt/β-catenin signaling cascade, including DKK1, NKD1 and GSK3β. These results demonstrate that miR-501-5p maintains constitutively activated wnt/β-catenin signaling by directly targeting DKK1, NKD1 and GSK3β, which promotes gastric cancer stem cell like phenotype.

Conclusions

Taken together, our findings reveal a new regulatory mechanism of miR-501-5p and suggest that miR-501-5p might be a potential target in gastric cancer therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0432-x) contains supplementary material, which is available to authorized users.