Clinical significance of LGR5 and CD44 expression in locally advanced rectal cancer after preoperative chemoradiotherapy

Cancer Stem Cell Biomarkers Predictive of Radiotherapy Response in Rectal Cancer: A Systematic Review

BACKGROUND

Rectal cancer (RC) is one of the most commonly diagnosed and particularly challenging tumours to treat due to its location in the pelvis and close proximity to critical genitourinary organs. Radiotherapy (RT) is recognised as a key component of therapeutic strategy to treat RC, promoting the downsizing and downstaging of large RCs in neoadjuvant settings, although its therapeutic effect is limited due to radioresistance. Evidence from experimental and clinical studies indicates that the likelihood of achieving local tumour control by RT depends on the complete eradication of cancer stem cells (CSC), a minority subset of tumour cells with stemness properties.

METHODS

A systematic literature review was conducted by querying two scientific databases (Pubmed and Scopus). The search was restricted to papers published from 2009 to 2021.

RESULTS

After assessing the quality and the risk of bias, a total of 11 studies were selected as they mainly focused on biomarkers predictive of RT-response in CSCs isolated from patients affected by RC. Specifically these studies showed that elevated levels of CD133, CD44, ALDH1, Lgr5 and G9a are associated with RT-resistance and poor prognosis.

CONCLUSIONS

This review aimed to provide an overview of the current scenario of in vitro and in vivo studies evaluating the biomarkers predictive of RT-response in CSCs derived from RC patients.

Multilevel regulation of Wnt signaling by Zic2 in colon cancer due to mutation of β-catenin

Zinc-finger of the cerebellum 2 (Zic2) is widely implicated in cancers, but the role of Zic2 in tumorigenesis is bilateral. A recent study indicated that Zic2 could render colon cancer cells more resistant to low glucose-induced apoptosis. However, the functional roles of Zic2 in colon cancer and the underlying molecular mechanism remain elusive. Herein, we demonstrated that Zic2 was highly expressed in colon cancer tissues and correlated with poor survival. Knockdown of Zic2 inhibited colon cancer cell growth, arrested the cell cycle transition from G0/G1 to S phase, and suppressed tumor sphere formation in vitro; in addition, silencing Zic2 retarded xenograft tumor formation in vivo. Consistently, ectopic expression of Zic2 had the opposite effects. Mechanistically, Zic2 executed its oncogenic role in colon cancer by enhancing Wnt/β-catenin signaling. Zic2 directly binds to the promoter of Axin2 and transcriptionally represses Axin2 expression and subsequently promotes the accumulation and nuclear translocation of β-catenin. Meanwhile, Zic2 could activate Wnt signaling by interacting with β-catenin. Intriguingly, in HCT116 cells with intrinsic Ser45 mutation of β-catenin, which blocks the degradation-related phosphorylation of β-catenin by CK1, modified Zic2 expression did not affect the protein level of β-catenin. Altogether, our findings uncover a novel multilevel mechanism for the oncogenic activity of Zic2 in colon cancer and suggest Zic2 as a potential therapeutic target for colon cancer patients.

Extracellular matrix and its therapeutic potential for cancer treatment

The extracellular matrix (ECM) is one of the major components of tumors that plays multiple crucial roles, including mechanical support, modulation of the microenvironment, and a source of signaling molecules. The quantity and cross-linking status of ECM components are major factors determining tissue stiffness. During tumorigenesis, the interplay between cancer cells and the tumor microenvironment (TME) often results in the stiffness of the ECM, leading to aberrant mechanotransduction and further malignant transformation. Therefore, a comprehensive understanding of ECM dysregulation in the TME would contribute to the discovery of promising therapeutic targets for cancer treatment. Herein, we summarized the knowledge concerning the following: (1) major ECM constituents and their functions in both normal and malignant conditions; (2) the interplay between cancer cells and the ECM in the TME; (3) key receptors for mechanotransduction and their alteration during carcinogenesis; and (4) the current therapeutic strategies targeting aberrant ECM for cancer treatment.

Still proliferating CD44+/Ki67+ tumor cells after neoadjuvant radiochemotherapy identify rectal cancer patients with poor survival

INTRODUCTION

Distant recurrence, especially liver metastases, occurs in one-third of rectal cancer patients initially treated with curative therapy and is still an unsolved problem. The identification of patients at risk is crucial for enabling individualized treatment.

MATERIAL AND METHODS

All patients undergoing curative resection for histologically confirmed rectal cancer after neoadjuvant radiochemotherapy between January 2001 and December 2015 were included. Sections were stained for Ki67, CD44, apoptosis and CD133. Patients were categorized based on whether they were found to have (CD44⁺/Ki67⁺) or not have (CD44⁺/Ki67⁺) still proliferating tumor cells.

RESULTS

218 patients who underwent R0 resection for stage I-III rectal cancer were selected. In 37 (17%) of these patients, CD44⁺/Ki67⁺ tumor cells were found. In multivariable Cox regression analysis, patients with CD44⁺/Ki67⁺ cells had significantly impaired overall (hazard ratio (HR): 3.84, 95% CI: 1.77-8.31, p = 0.001) and relative survival (HR 3.44, 95% CI: 1.46-8.09). The previous results were confirmed after propensity-score matching. In mediation-analysis, the presence of CD44⁺/Ki67⁺ cells was associated with a substantial direct effect on overall (HR 1.92, 95% CI: 1.09-9.28) and relative survival (HR 1.63, 95% CI: 1.31-6.38).

CONCLUSIONS

The presence of still proliferating CD44⁺/Ki67⁺ tumor cells after neoadjuvant radiochemotherapy was associated with impaired oncological long-term outcomes. Characterization of these cells should be performed.

The Association Between Inflammation, Epithelial Mesenchymal Transition and Stemness in Colorectal Carcinoma

Background

Inflammation plays an important albeit dual role in carcinogenesis. Survival studies have highlighted the prognostic significance of peritumorous inflammation. Currently, the theoretical background allows inflammation, epithelial mesenchymal transition (EMT) and the closely associated stem cell differentiation in colorectal carcinoma (CRC) to be linked. However, there is scarce direct morphological evidence.

Purpose and methods

The aim of our study was to investigate the role of inflammation in cancer growth and invasion by analyzing the association between inflammation and known morphological prognostic features of colorectal cancer, EMT, stemness and mismatch repair (MMR) protein expression. The study was designed as a retrospective morphological and immunohistochemical assessment of 553 consecutive cases of surgically treated primary CRC.

Results

There were statistically significant associations between high-grade inflammation and lower pT (p = 0.002), absence of lymph node metastases (p < 0.001) and less frequent lymphatic (p = 0.003), venous (p = 0.017), arterial (p = 0.012), perineural (p = 0.001) and intraneural (p = 0.01) invasion. In contrast, Crohn's like reaction (CLR) by density of lymphoid follicles in the invasive front lacked significant differences in regard to pT, pN, tumor invasion into surrounding structures (blood or lymphatic vessels, nerves), grade or necrosis (all p > 0.05). The expression of E-cadherin, CD44 and MMR proteins yielded no statistically significant associations with peritumorous inflammation by Klintrup-Mäkinen score or the density of lymphoid follicles. Nevertheless, E-cadherin levels were significantly associated with the density of eosinophils (p = 0.007).

Conclusion

High-grade peritumorous inflammation is associated with beneficial morphologic CRC features, including less frequent manifestations of invasion, and is not secondary to tissue damage and necrosis. CLR is not associated with cancer spread by pTN; this finding indirectly suggests an independent role of CLR in carcinogenesis. Further, inflammation by Klintrup-Mäkinen grade and CLR is not dependent on epithelial-mesenchymal transition and stem cell differentiation. Our study highlights the complex associations between inflammation, tumor morphology, EMT, stemness and MMR protein expression in human CRC tissues.

Telomere Maintenance-Associated PML Is a Potential Specific Therapeutic Target of Human Colorectal Cancer

Telomere length maintenance is essential for cell proliferation, which is particularly prominent in cancer. We validate that the primary colorectal tumors exhibit heterogeneous telomere lengths but mostly (90%) short telomeres relative to normal tissues. Intriguingly, relatively short telomeres are associated with tumor malignancy as indicated by poorly differentiated state, and these tumors contain more cancer stem-like cells (CSLCs) identified by several commonly used markers CD44, EPHB2 or LGR5. Moreover, promyelocytic leukemia (PML) and ALT-associated PML nuclear bodies (APBs) are frequently found in tumors with short telomeres and high proliferation. In contrast, distant normal tissues rarely or only minimally express PML. Inhibition of PML and APBs by an ATR inhibitor decreases proliferation of CSLCs and organoids, suggesting a potential therapeutic target to progressive colorectal tumors. Together, telomere maintenance underling tumor progression is connected with CSLCs.

The Prognostic and Clinical Value of CD44 in Colorectal Cancer: A Meta-Analysis

Background: CD44 is widely used as a putative cancer stem cells (CSCs) marker for colorectal cancer (CRC). However, the prognostic role of CD44 in CRC remains controversial. Methods: We performed a systematic review and meta-analysis to evaluate the association of various CD44 isoforms and overall survival (OS) and clinicopathological features of CRC patients. Results: A total of 48 studies were included in the meta-analysis. Total CD44 isoforms overexpression was significantly correlated with worse OS of patients with CRC (HR = 1.32, 95% CI = 1.08-1.61, P = 0.007). In a stratified analysis, a higher level of either CD44v6 or CD44v2 had an unfavorable impact on OS (HR_CD44v6 = 1.50, 95% CI = 1.10-2.14, P = 0.010; HR_CD44v2 = 2.93, 95% CI = 1.49-5.77, P = 0.002). Additionally, CD44 was shown to be associated with some clinicopathological features, such as lymph node metastasis (OR_CD44 = 1.56, 95% CI = 1.01-2.41, P = 0.044; OR_CD44v6 = 1.97, 95% CI = 1.19-3.26, P = 0.008; OR_{Total CD44 isoforms} = 1.57, 95% CI = 1.15-2.14, P = 0.004), distant metastasis (OR_CD44 = 2.90, 95% CI = 1.08-7.83, P = 0.035; OR_{Total CD44 isoforms} = 1.89, 95% CI = 1.02-3.53, P = 0.044). Moreover, a high level of CD44 showed a possible correlation with poor differentiation (OR_{Total CD44 isoforms} = 1.44, 95% CI = 1.00-2.08, P = 0.051), elevated level of CD44v6 tend to be correlated with tumor size (OR = 1.71, 95% CI = 0.99-2.96, P = 0.056). Conclusions: This meta-analysis demonstrated that CD44 overexpression might be an unfavorable prognostic factor for CRC patients and could be used to predict poor differentiation, lymph node metastasis and distant metastasis.

CD133 expression predicts post-operative recurrence in patients with colon cancer with peritoneal metastasis

Despite extensive research on cancer stem cells in colorectal cancer, the impact of stem cell markers on patient survival remains unclear, particularly in those with distant metastasis. In this study, we focused on colon cancer with peritoneal metastasis and investigated the association between the expression of CD133, aldehyde dehydrogenase-1 (ALDH1) and leucine-rich repeating G-protein coupled receptor-5 (Lgr5), and disease prognosis. Putative stem cell marker expression was immunohistochemically evaluated in samples from 142 primary tumours and 75 peritoneal nodules. The associations between the expression of these markers and clinicopathological characteristics, overall survival and disease-free survival were analysed. The expression of CD133, ALDH1 and Lgr5 was found to be positive in 55.6, 47.2 and 78.9% of the primary tumour samples, respectively. While their expression was not associated with overall survival, disease-free survival was significantly worse in the CD133‑negative group (36.1 vs. 13.7%, P=0.041). Multivariable analysis confirmed that a negative CD133 expression was an independent risk factor for a reduced disease-free survival (P=0.005). Furthermore, the benefit of systemic chemotherapy was significantly greater in the CD133-negative group (P=0.039). On the whole, our data indicated that patients with colon cancer with CD133-negative expression had a reduced disease-free survival. Thus, we propose that CD133 expression may be a useful clinical biomarker in the treatment of colon cancer with peritoneal metastasis.

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.

WD-repeat protein WDR13 is a novel transcriptional regulator of c-Jun and modulates intestinal homeostasis in mice

Background

WDR13 is a member of the WD repeat protein family and is expressed in several tissues of human and mice. Previous studies in our laboratory showed that the lack of this gene in mice resulted in mild obesity, hyperinsulinemia, enhanced beta cell proliferation and protection from inflammation. However, the molecular mechanism of WDR13 action is not well understood.

Methods

In the present study, we used AOM/DSS to induce colitis-mediated colorectal tumor after establishing expression of Wdr13 gene in colon. Further, we have used human colon cancer cell lines, HT29 and COLO205, and mouse primary embryonic fibroblast to understand the molecular mechanism of WDR13 action.

Results

We observed that mice lacking Wdr13 gene have reduced number of tumors and are more susceptible to DSS-induced colon ulcers. We also show that WDR13 is a part of multi protein complex c-Jun/NCoR1/HDAC3 and it acts as a transcriptional activator of AP1 target genes in the presence of JNK signal. Consistent with in vitro data, we observed reduced expression of AP1 target genes in colon after AOM/DSS treatment in Wdr13 knockout mice as compared to that in wild type.

Conclusion

Mice lacking Wdr13 gene showed reduced expression of AP1 target genes and protection from colitis-induced colorectal tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3118-7) contains supplementary material, which is available to authorized users.

Olfactory Receptor Family 7 Subfamily C Member 1 Is a Novel Marker of Colon Cancer-Initiating Cells and Is a Potent Target of Immunotherapy

PURPOSE

Cancer-initiating cells (CICs) are thought to be essential for tumor maintenance, recurrence, and distant metastasis, and they are therefore reasonable targets for cancer therapy. Cancer immunotherapy is a novel approach to target cancer. In this study, we aimed to establish novel CIC-targeting immunotherapy.

EXPERIMENTAL DESIGN

Colorectal cancer (CRC) CICs were isolated as side population (SP) cells. The gene expression profile of CRC CICs was analyzed by cDNA microarray and RT-PCR. Protein expression of olfactory receptor family 7 subfamily C member 1 (OR7C1) were analyzed by Western blot and immunohistochemical staining. The functions of OR7C1 were analyzed by gene overexpression and gene knockdown using siRNAs. OR7C1-positive cells were isolated by a flow cytometer and analyzed. CTLs specific for OR7C1 peptide were generated, and the antitumor effect was addressed by mice adoptive transfer model.

RESULTS

OR7C1 has essential roles in the maintenance of colon CICs, and the OR7C1-positive population showed higher tumorigenicity than that of the OR7C1-negative population, indicating that OR7C1 is a novel functional marker for colon CIC. Immunohistochemical staining revealed that OR7C1 high expression was correlated with poorer prognosis in CRC patients. OR7C1-derived antigenic peptide-specific CTLs showed specific cytotoxicity for CICs, and an OR7C1-specific CTL clone showed a greater antitumor effect than did a CTL clone targeting all cancer cells in a CTL adoptive transfer mouse model.

CONCLUSIONS

OR7C1 is a novel marker for colon CICs and can be a target of potent CIC-targeting immunotherapy. Clin Cancer Res; 22(13); 3298-309. ©2016 AACR.

Lgr5 expression is a valuable prognostic factor for colorectal cancer: evidence from a meta-analysis

Background

Lgr5 has recently been identified as a reliable biomarker of cancer stem cells (CSCs) in colorectal cancer (CRC); however, its prognostic value is still controversial.

Methods

We searched PubMed, Web of Science, and Wanfang databases with identical strategies to retrieve articles. We evaluated the impact of Lgr5 expression on survival of CRC patients through meta-analysis.

Results

A total of 12 studies comprising 2600 patients revealed that Lgr5 overexpression was negatively associated with overall survival (OS) (HR = 1.73, 95 % CI: 1.28–2.33; P = 0.00) and disease free survival (DFS) (HR = 2.89, 95 % CI: 1.89–4.44; P = 0.000) in CRC patients. Subgroup analysis suggested that Lgr5 overexpression was significantly associated with worse OS in subgroups with IHC as the method of Lgr5 assessment (HR = 2.01, 95 % CI: 1.39–2.89; P = 0.001), patients from Asia (HR = 1.81, 95 % CI: 1.27–2.58; P = 0.000), and NOS scores greater than 6 (HR = 2.12, 95 % CI: 1.41–3.19; P = 0.000). Furthermore, sensitivity analysis showed that the estimated HR ranged from 1.6 to 1.86 upon excluding one study sequentially from each analysis. In addition, Lgr5 overexpression was significantly associated with deep invasion of CRC (OR = 0.39, 95 % CI: 0.17–0.87; P = 0.002), lymphnode metastasis (OR = 0.45, 95 % CI: 0.26–0.76; P = 0.003), distant metastasis (OR = 0.37, 95 % CI: 0.22–0.62; P = 0.000), and AJCC stage (OR = 0.35, 95 % CI: 0.15–0.78; P = 0.01). However, Lgr5 overexpression was not correlated with tumor grade (OR = 0.75 95 % CI: 0.37–1.54; P = 0.433).

Conclusions

This study shows that Lgr5 can be a valuable and reliable prognostic factor of colorectal cancer progression.

Lgr5 expression is a valuable prognostic factor for colorectal cancer: evidence from a meta-analysis

Background

Lgr5 has recently been identified as a reliable biomarker of cancer stem cells (CSCs) in colorectal cancer (CRC); however, its prognostic value is still controversial.

Methods

We searched PubMed, Web of Science, and Wanfang databases with identical strategies to retrieve articles. We evaluated the impact of Lgr5 expression on survival of CRC patients through meta-analysis.

Results

A total of 12 studies comprising 2600 patients revealed that Lgr5 overexpression was negatively associated with overall survival (OS) (HR = 1.73, 95 % CI: 1.28–2.33; P = 0.00) and disease free survival (DFS) (HR = 2.89, 95 % CI: 1.89–4.44; P = 0.000) in CRC patients. Subgroup analysis suggested that Lgr5 overexpression was significantly associated with worse OS in subgroups with IHC as the method of Lgr5 assessment (HR = 2.01, 95 % CI: 1.39–2.89; P = 0.001), patients from Asia (HR = 1.81, 95 % CI: 1.27–2.58; P = 0.000), and NOS scores greater than 6 (HR = 2.12, 95 % CI: 1.41–3.19; P = 0.000). Furthermore, sensitivity analysis showed that the estimated HR ranged from 1.6 to 1.86 upon excluding one study sequentially from each analysis. In addition, Lgr5 overexpression was significantly associated with deep invasion of CRC (OR = 0.39, 95 % CI: 0.17–0.87; P = 0.002), lymphnode metastasis (OR = 0.45, 95 % CI: 0.26–0.76; P = 0.003), distant metastasis (OR = 0.37, 95 % CI: 0.22–0.62; P = 0.000), and AJCC stage (OR = 0.35, 95 % CI: 0.15–0.78; P = 0.01). However, Lgr5 overexpression was not correlated with tumor grade (OR = 0.75 95 % CI: 0.37–1.54; P = 0.433).

Conclusions

This study shows that Lgr5 can be a valuable and reliable prognostic factor of colorectal cancer progression.

LGR5, a relevant marker of cancer stem cells, indicates a poor prognosis in colorectal cancer patients: a meta-analysis

BACKGROUND

Leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) has been identified as a putative intestinal stem cell marker. However, the clinical prognosis of Lgr5 is still controversial in colorectal cancer (CRC). To systematically summarize the clinical prognostic function of Lgr5 in colorectal cancer, we performed this meta-analysis.

METHODS

Published articles which assessed the clinical or prognostic role of Lgr5 was searched in Pubmed, Embase and Springer and collected until the publication month of February 2014. The association of Lgr5 expression with clinical outcomes was investigated by a meta- analysis.

RESULTS

A total of 8 studies have been up to the inclusion standard, comprised 2139 patients. Lgr5 showed no relationship with the gender of patients (OR=0.919, 95% CI=0.730-1.157, P=0.473) and the depth of invasion (OR=2.616, CI 95%=0.947-7.221, P=0.063). Lgr5 was significantly associated with lymph node metastasis (OR=2.248, 95%CI=1.205-4.192, P=0.011), tumor distance metastasis (OR=3.872, 95%CI=2.792-5.370, P<0.001) and classification of TNM (pooled OR=3.264, 95% CI=1.731-6.155, P<0.001). Overall, overexpression of Lgr5 was statistically related to the reduced overall survival (HR=6.130, 95% CI=2.845-13.210, P<0.001).

CONCLUSIONS

Lgr5 participates in the progression of CRC as a putative factor. Overexpression of Lgr5 was distinctly correlated with poor patient survival. These findings suggested that Lgr5 might serve as an efficient biomarker for prognostic indicator, and could be a new molecular target in colorectal cancer therapy.

Prognostic value of LGR5 in colorectal cancer: a meta-analysis

Objective

Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) has recently been reported to be a marker of cancer stem cells (CSCs) in colorectal cancer (CRC), and the prognostic value of LGR5 in CRC has been evaluated in several studies. However, the conclusions remain controversial. In this study, we aimed to evaluate the association between the expression of LGR5 and the outcome of CRC patients by performing a meta-analysis.

Methods

We systematically searched for relevant studies published up to February 2014 using the PubMed, Web of Science, EMBASE and Wangfang databases. Only articles in which LGR5 expression was detected by immunohistochemistry were included. A meta-analysis was performed using STATA 12.0, and pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were used to estimate the strength of the association between LGR5 expression and the prognosis of CRC patients.

Results

A total of 7 studies comprising 1833 CRC patients met the inclusion criteria, including 6 studies comprising 1781 patients for overall survival (OS) and 3 studies comprising 528 patients for disease-free survival (DFS). Our results showed that high LGR5 expression was significantly associated with poor prognosis in terms of OS (HR: 1.87, 95% CI: 1.23–2.84; P = 0.003) and DFS (HR: 2.44, 95% CI: 1.49–3.98; P<0.001). Further subgroup analysis revealed that many factors, including the study region, number of patients, follow-up duration and cutoff value, affected the significance of the association between LGR5 expression and a worse prognosis in patients with CRC. In addition, there was no evidence of publication bias, as suggested by Begg’s and Egger’s tests.

Conclusions

The present meta-analysis indicated that high LGR5 expression was associated with poor prognosis in patients with CRC and that LGR5 is an efficient prognostic factor in CRC.

Prognostic significance of CD44 variant 2 upregulation in colorectal cancer

Background:

CD133 and CD44 are putative cancer stem cell (CSC) markers in colorectal cancer (CRC). However, their clinical significance is currently unclear. Here, we evaluated primary CRC cell isolates to determine the significance of several CSC markers, including CD133 and CD44, as predictors of tumourigenesis and prognosis.

Methods:

CD133- and CD44-positive cells from fresh clinical samples of 77 CRCs were selected by flow cytometric sorting and evaluated for tumourigenicity following subcutaneous transplantation into NOD/SCID mice. Cancer stem cell marker expression was examined in both xenografts and a complementary DNA library compiled from 167 CRC patient samples.

Results:

CD44⁺, CD133⁺ and CD133⁺CD44⁺ sub-populations were significantly more tumourigenic than the total cell population. The clinical samples expressed several transcript variants of CD44. Variant 2 was specifically overexpressed in both primary tumours and xenografts in comparison with the normal mucosa. A prognostic assay using qRT–PCR showed that the CD44v2^high group (n=84, 5-year survival rate (5-OS): 0.74) had a significantly worse prognosis (P=0.041) than the CD44v2^low group (n=83, 5-OS: 0.88).

Conclusions:

CD44 is an important CSC marker in CRC patients. Furthermore, CRC patients with high expression of CD44v2 have a poorer prognosis than patients with other CD44 variants.

Increased expression of Lgr5 is associated with chemotherapy resistance in human gastric cancer

Leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5), a marker of adult stem cells and cancer stem cells, plays important roles in tumor progression. Furthermore, Lgr5 also contributes to chemoradiotherapy resistance. However, the function of Lgr5 in the prediction of preoperative chemotherapy efficacy has not been reported. We evaluated the potential of Lgr5 in predicting tumor response and overall survival in advanced gastric cancer treated with preoperative chemotherapy. The association between Lgr5 and chemotherapy resistance was also investigated in gastric cancer cell lines. Hematoxylin and eosin staining and immunohistochemical analysis of Lgr5 expression were performed in 68 cases of gastric cancer treated with preoperative chemotherapy. Lgr5 expression was specifically silenced in the AGS gastric cancer cell lines by RNA interference. Levels of Lgr5 mRNA and protein in cell lines were detected by quantitative reverse transcription-polymerase chain reaction or western blotting. Cell viability was evaluated by an MTT assay. Cell apoptosis was assessed by Annexin V-FITC/propidium iodide dual staining analysis. We found that Lgr5 expression was significantly associated with tumor regression grade after preoperative chemotherapy. The rate of positive Lgr5 expression was significantly higher in patients with poor tumor regression compared with those exhibiting tumor regression (P=0.001). Lgr5-positive patients had a significantly shorter survival time than Lgr5-negative patients (P=0.001). Inhibition of Lgr5 expression with small interfering RNA increased the sensitivity of AGS gastric cancer cells to chemotherapy. Our findings suggest that Lgr5 expression may be implicated in the chemoresistance of gastric cancer cells and is a potential novel biomarker for predicting response to chemotherapy and prognosis in gastric cancer patients, and may also represent a potential new therapeutic target for cancer therapy.

Progress in understanding the relationship between Lgr5 and colorectal cancer

Leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5), a member of the G protein-coupled receptor family, contains 17 leucine-rich repeats and N- and C-terminal cysteine-rich flanking domains. Lgr5 is a marker for stem cells in the stomach, small intestine, colon, and hair follicles. Recently, Lgr5 has been identified as a target of Wnt signaling. As a potential marker for colorectal cancer stem cells, Lgr5 might be responsible for the initiation and progression of colorectal cancer. In this article we review recent progress in understanding the relationship between Lgr5 and colorectal cancer.