CD44 but not CD24 expression is related to poor prognosis in non-cardia adenocarcinoma of the stomach

Pan-cancer and single-cell analyses identify CD44 as an immunotherapy response predictor and regulating macrophage polarization and tumor progression in colorectal cancer

Introduction

Cluster of differentiation (CD) 44 is a non-kinase cell surface transmembrane glycoprotein critical for tumor maintenance and progression.

Methods

We conducted a systematic analysis of the expression profile and genomic alteration profile of CD44 in 33 types of cancer. The immune characteristics of CD44 were comprehensively explored by TIMER2.0 and CIBERSORT. In addition, the CD44 transcriptional landscape was examined at the single-cell level. Then, Pseudotime trajectory analysis of CD44 gene expression was performed using Monocle 2, and CellChat was utilized to compare the crosstalk differences between CD44+monocytes and CD44- monocytes. Tumor immune dysfunction and exclusion (TIDE) was used to evaluate the predictive ability of CD44 for immune checkpoint blockade (ICB) responses. The effects of CD44 on colorectal cancer (CRC) and macrophage polarization were investigated by knocking down the expression of CD44 in HCT-116 cell and macrophages in vitro.

Results

The expression of CD44 elevated in most cancers, predicting unfavorable prognosis. In addditon, CD44 was correlation with immune cell infiltration and key immune regulators. CD44+ monocytes had a higher information flow intensity than CD44- monocytes. CD44 had good predictive ability for immune checkpoint blockade responses. Knockdown of CD44 inhibited the proliferation, migration, and invasion of HCT-116 cell in vitro. Knockdown of CD44 inhibited M2 macrophage polarization.

Discussion

These findings suggest that CD44 is involved in regulating tumor development, macrophage polarization, and has certain predictive value for patient clinical prognosis and response to immunotherapy.

Exosomes: A potential tool for immunotherapy of ovarian cancer

Ovarian cancer is a malignant tumor of the female reproductive system, with a very poor prognosis and high mortality rates. Chemotherapy and radiotherapy are the most common treatments for ovarian cancer, with unsatisfactory results. Exosomes are a subpopulation of extracellular vesicles, which have a diameter of approximately 30-100 nm and are secreted by many different types of cells in various body fluids. Exosomes are highly stable and are effective carriers of immunotherapeutic drugs. Recent studies have shown that exosomes are involved in various cellular responses in the tumor microenvironment, influencing the development and therapeutic efficacy of ovarian cancer, and exhibiting dual roles in inhibiting and promoting tumor development. Exosomes also contain a variety of genes related to ovarian cancer immunotherapy that could be potential biomarkers for ovarian cancer diagnosis and prognosis. Undoubtedly, exosomes have great therapeutic potential in the field of ovarian cancer immunotherapy. However, translation of this idea to the clinic has not occurred. Therefore, it is important to understand how exosomes could be used in ovarian cancer immunotherapy to regulate tumor progression. In this review, we summarize the biomarkers of exosomes in different body fluids related to immunotherapy in ovarian cancer and the potential mechanisms by which exosomes influence immunotherapeutic response. We also discuss the prospects for clinical application of exosome-based immunotherapy in ovarian cancer.

Claudin-6 increases SNAI1, NANOG and SOX2 gene expression in human gastric adenocarcinoma AGS cells

BACKGROUND

Gastric cancer is a heterogeneous disease associated to deregulated gastric epithelia tight junction barrier function and di novo expression of claudin-6; these changes are associated with epithelial-mesenchymal transition, enhanced invasiveness, metastatic progression, resistance to chemotherapy, and poor prognosis. Gastric cancer stem cells represent a rare population of cells within the tumor implicated in tumor growth and higher tumorigenic capacity. The possible relation between claudin-6 expression and the expression of some markers associated to epithelial mesenchymal transition and cancer stem cells in gastric cancer cells have never been explored.

METHODS AND RESULTS

CD44, CD24, Twist, Villin, DCLK1, claudin-6, NANOG, E-Cadherin, SOX2, and SNAI1 expression was evaluated by immunofluorescence and cytofluorometry in wild type and Claudin-6 transfected AGS cells. Cell migration assays were also performed. Differentially expressed genes and biological processes analysis was performed to determine gene preponderance. The results showed that claudin-6 overexpression enriched the CD44 + /CD24- subpopulation with an overall increase in the expression and the number of CD44 + cells. A significant increase in NANOG, SOX2 and SNAI1 expression and enhanced cell migration was observed in claudin-6 transfected cells. Transcriptome analysis revealed 271 genes involved in enhanced biological processes with only 31 with a significantly p value; thirteen of those genes are closely associated to epithelial mesenchymal transition processes and folding and unfolding processes of proteins in the endoplasmic reticulum.

CONCLUSIONS

The pro-tumorigenic effect of claudin-6 in gastric cancer could be associated to dedifferentiation of epithelial cells and an increase in di novo cancer stem cell genesis.

Increased CD44 Expression and MEK Activity Predict Worse Prognosis in Gastric Adenocarcinoma Patients Undergoing Gastrectomy

PURPOSE

We have shown that activation of the receptor tyrosine kinase (RTK)-RAS pathway in gastric adenocarcinoma (GA) promotes acquisition of cancer stem-like cell (CSC) phenotypes including metastasis and chemotherapy resistance. Here, we evaluated the prognostic value of the CSC marker CD44 and the RTK-RAS activation marker phosphorylated MEK (p-MEK) in patients with resectable GA.

METHODS

CD44 and p-MEK were measured in tumors from GA patients who underwent curative-intent gastrectomy at Fujian Medical University Union Hospital (FMUUH, n = 134) and Memorial Sloan Kettering Cancer Center (MSKCC, n = 56). Overall survival (OS) was estimated by the Kaplan-Meier method, and multivariate analysis was performed by Cox proportional hazards regression modeling.

RESULTS

Despite multiple significant differences in clinicopathologic characteristics between the FMUUH and MSKCC cohorts, high CD44 and high p-MEK expression were both independent negative prognostic factors for OS on univariate analysis in both cohorts (p < 0.05). Both factors were also significant on multivariate analysis when the cohorts were combined (p ≤ 0.003). On subgroup analysis, the 5-year OS of patients with both high CD44 and high p-MEK was 39.5-41.6% compared with 55.4-66.4% for patients with low CD44. High CD44 expression was associated with more advanced TNM stage in the FMUUH cohort and larger tumor size and undifferentiated histology in the MSKCC cohort. High p-MEK was associated with undifferentiated histology in the FMUUH cohort and larger tumor size in the MSKCC cohort.

CONCLUSIONS

Increased CD44 and p-MEK expression are predictive of worse OS in GA patients. Thus, targeting the RTK-RAS pathway may benefit patients with CD44-positive, RAS-activated GA by inhibiting metastasis and reversing chemotherapy resistance.

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.

Prognostic Value of Cyclin D1 and CD44 Expression in Gastric Adenocarcinoma

BACKGROUND

Worldwide, gastric carcinoma (GC) is the 5th most common malignancies in both sexes representing 6.8% of the total fatalities and is the 3rd leading cause of cancer death representing 8.8% of total fatalities. In Egypt, GC considers the 12th leading cause of cancer death representing 2.2% of the total cancer mortality. A growing body of evidence supports that cancer stem cells (CSCs) are resistant to chemotherapy or radiation, and the cell adhesion molecule CD44 has been identified as a cell surface marker associated with cancer stem cell in several types of tumors including gastric cancer. CD44 regulates gastric stem cell proliferation by increasing cyclin D1 expression which represents an important regulatory protein in the cell cycle transition from G1 phase to S phase. This study aimed to investigate whether cyclin D1 and CD44 can be used as prognostic indicators in gastric cancer.

MATERIAL AND METHODS

Forty formalin-fixed and paraffin-embedded gastric tissues, obtained from patients who underwent endoscopic resection or surgical resection, constituted the group of our study. The immunohistochemical expression of cyclin D1 and CD44 was examined and correlated with clinical-pathological parameters and outcome of the patients.

RESULTS

Overexpression of CD44 and cyclin D1 was noted (in of 55 and 50% respectively). Cyclin D1 and CD44 positive expressions in GC were positively correlated with tumor differentiation (p = 0.020, p = 0.004 respectively), TNM stage (p < 0.001 for both), poor survival (p < 0.001 for both), and with increased rate of recurrence (p = 0.020, p = 0.005 respectively).

CONCLUSION

CD44 and cyclin D1 were associated with poor prognosis in gastric cancer, and so, they comprise an attractive target for anticancer drug development.

The survival analysis and oncogenic effects of CFP1 and 14-3-3 expression on gastric cancer

Background & aim

Gastric cancer (GC) is the third-leading cause of cancer-related deaths. We established a prospective database of patients with GC who underwent surgical treatment. In this study, we explored the prognostic significance of the expression of CFP1 and 14-3-3 in gastric cancer, by studying the specimens collected from clinical subjects.

Materials & methods

Immunohistochemistry was used to detect the expression of CFP1 and 14-3-3 in 84 GC subjects, including 73 patients who have undergone radical gastrectomy and 11 patients who have not undergone radical surgery. Survival analysis was performed by km-plot data.

Results

According to the survival analysis, we can see that the survival time of patients with high expression of CFP1 is lower than the patients with low expression in gastric cancer, while the effect of 14-3-3 is just the opposite. The survival time of patients with higher expression of 14-3-3 is also longer.

Conclusion

The CFP1 and 14-3-3 genes can be used as prognostic markers in patients with GC, but the study is still needed to confirm.

CD44s Assembles Hyaluronan Coat on Filopodia and Extracellular Vesicles and Induces Tumorigenicity of MKN74 Gastric Carcinoma Cells

CD44 is a multifunctional adhesion molecule typically upregulated in malignant, inflamed and injured tissues. Due to its ability to bind multiple ligands present in the tumor microenvironment, it promotes multiple cellular functions related to tumorigenesis. Recent data has shown that CD44 and its principal ligand hyaluronan (HA) are carried by extracellular vesicles (EV) derived from stem and tumor cells, but the role of CD44 in EV shedding has not been studied so far. To answer this question, we utilized CD44-negative human gastric carcinoma cell line MKN74 manipulated to stably express CD44 standard form (CD44s). The effect of CD44s expression on HA metabolism, EV secretion, morphology and growth of these cells was studied. Interestingly, HAS2 and HYAL2 expression levels were significantly upregulated in CD44s-expressing cells. Cell-associated HA levels were significantly increased, while HA levels in the culture medium of CD44s-positive cells was lower compared to CD44s-negative MOCK cells. CD44s expression had no significant effect on the proliferation capacity of cells, but cells showed diminished contact inhibition. Superresolution imaging revealed that CD44s and HA were accumulated on filopodia and EVs secreted from CD44s-positive cells, but no differences in total numbers of secreted EV between CD44s-negative and -positive cells was detected. In 3D cultures, CD44s-expressing cells had an enhanced invasion capacity in BME gel and increased spheroidal growth when cultured in collagen I gel. No significant differences in mitotic activity, tumor size or morphology were detected in CAM assays. However, a significant increase in HA staining coverage was detected in CD44s-positive tumors. Interestingly, CD44s-positive EVs embedded in HA-rich matrix were detected in the stromal areas of tumors. The results indicate that CD44s expression significantly increases the HA binding capacity of gastric cancer cells, while the secreted HA is downregulated. CD44s is also carried by EVs secreted by CD44s-expressing cells. These findings highlight the potential usefulness of CD44s and its ligands as multipurpose EV biomarkers, because they are upregulated in inflammatory, injured, and cancer cells and accumulate on the surface of EVs secreted in these situations.

The most reliable surface marker for the identification of colorectal cancer stem-like cells: A systematic review and meta-analysis

Several surface markers have been proposed for the identification and characterization of colorectal cancer stem-like cells (CR-CSLCs). However, their reliability in CR-CSLCs identification remains controversial. This study evaluated the correlation between all candidate surface marker's expression and CSLCs properties (tumorigenicity) through monitoring in vivo tumor incidence and final tumor volume. PubMed, Web of Science, and Scopus databases were systematically searched until November 2017. A total of 27 studies were found that met the inclusion criteria for cluster of differentiation 133 (CD133) and CD44 markers. Results indicated that either CD133 or CD44 positive cells caused about twofold increase in tumor volume compared with the negative cells (p < 0.05). In two groups of cells derived from primary tumors and cell lines, CD133 ⁺ cells had 25 and 1.45 times higher tumor incidence potential than CD133 ^- cells, respectively ( p < 0.05). Also, cohort evaluation showed that CD133 overexpression at protein level is a marker of poor overall survival in colorectal cancer (CRC) patients. While CD44 ⁺ cells displayed twofold tumorigenicity compared with the negative cells ( p < 0.05), combination of CD44 and CD133 showed about sevenfold tumorigenicity potential ( p < 0.05). In conclusion, the present meta-analysis suggests that CD133 is a robust biomarker to identify primary tumor CSLCs and can be proposed as a prognostic marker of CRC patient whereas it should be used with caution in cell lines. It seems to be more reliable to use CD133 in combination with CD44 as target biomarkers for the isolation of CR-CSLCs in both cell line and primary tumor cells populations.

Clinicopathological significance of claspin overexpression and its association with spheroid formation in gastric cancer

Gastric cancer (GC) is one of the leading causes of cancer-related death worldwide. Spheroid colony formation is a useful method to identify cancer stem cells (CSCs). The aim of this study was to identify a novel prognostic marker or therapeutic target for GC using a method to identify CSCs. We analyzed the microarray data in spheroid body-forming and parental cells and focused on the CLSPN gene because it is overexpressed in the spheroid body-forming cells in both the GC cell lines MKN-45 and MKN-74. Quantitative reverse-transcription polymerase chain reaction analysis revealed that CLSPN messenger RNA expression was up-regulated in GC cell lines MKN-45, MKN-74, and TMK-1. Immunohistochemistry of claspin showed that 94 (47%) of 203 GC cases were positive. Claspin-positive GC cases were associated with higher T and N grades, tumor stage, lymphatic invasion, and poor prognosis. In addition, claspin expression was coexpressed with CD44, human epidermal growth factor receptor type 2, and p53. CLSPN small interfering RNA treatment decreased GC cell proliferation and invasion. These results indicate that the expression of claspin might be a key regulator in the progression of GC and might play an important role in CSCs of GC.

Polymorphisms of cancer stem cell marker gene CD133 are associated with susceptibility and prognosis of gastric cancer

AIM

This study was aimed to investigate the associations between single nucleotide polymorphisms of cancer stem cell marker genes, CD44 and CD133, and susceptibility and prognosis of gastric cancer.

PATIENTS & METHODS

Five single nucleotide polymorphisms in CD44 and CD133 genes were genotyped in 898 gastric cancer cases and 992 controls.

RESULTS

The A/C or C/C genotypes of CD133 rs2240688 were associated with decreased risk of gastric cancer comparing with the A/A genotype (odds ratio: 0.81; 95% CI: 0.67-0.97; p = 0.023). The T allele of CD133 rs3130 predicted a worse survival for gastric cancer patients receiving tumorectomy (hazard ratio: 1.28; 95% CI: 1.04-1.58; p = 0.020), independent from tumor node metastasis stage, vessel invasion and postoperational chemotherapy.

CONCLUSION

 CD133 polymorphisms are promising biomarkers for genetic susceptibility and prognosis prediction of gastric cancer.

Hypoxia regulates CD44 expression via hypoxia-inducible factor-1α in human gastric cancer cells

Hypoxia induces proliferation and invasion in cancer cells via hypoxia-inducible factor (HIF)-1α. The cell adhesion molecule cluster of differentiation (CD) 44 has been associated with increased cell invasion and metastasis. Whether hypoxia regulates the expression of CD44 in gastric cancer cells remains to be established. In the current study, the effects of hypoxia on HIF-1α and CD44 expression levels in human gastric cell lines SGC-7901 and BGC-823 were evaluated. The cells were cultured in 1% O₂ for 1 week and then treated with 20 nM rapamycin for 72 h. Cell viability was evaluated using the Cell Counting kit-8 assay, and cell invasion was detected by the Transwell invasion assay. The protein and messenger (m) RNA expression levels of HIF-1α and CD44 were detected using western blotting and reverse transcription-quantitative polymerase chain reaction, respectively. The results revealed that cell viability and invasion increased under hypoxic conditions, but decreased following rapamycin treatment in SGC-7901 and BGC-823 cells. Hypoxia also increased the protein and mRNA expression levels of HIF-1α and CD44 in these two cell lines. However, this hypoxia-induced increase in HIF-1α and CD44 protein and mRNA expression levels was inhibited by rapamycin. These findings suggest that hypoxia induced the proliferation and invasion of SGC-7901 and BGC-823 cells. Furthermore, CD44 expression levels were potentially associated with HIF-1α expression levels. Therefore, in gastric cancer cells, hypoxia may regulate CD44 expression via HIF-1α in order to promote cell proliferation and invasion.

Prognostic impact of CD44-positive cancer stem-like cells at the invasive front of gastric cancer

Background:

The invasive tumour front may provide prognostic information. We examined the relationship between the presence of cancer stem cells (CSCs) at the invasive tumour front and prognosis in gastric cancer (GC).

Methods:

CD44 is a CSC marker; accordingly, CD44 standard (CD44s), CD44 variant-6 (CD44v6), and CD44 variant-9 (CD44v9) expression were examined in 123 resected primary GCs and the clinical significance of CSCs at the invasive tumour front was analysed.

Results:

Thirteen (10.6%), 79 (64.2%), and 47 (38.2%) GCs were CD44s-, CD44v6-, and CD44v9-positive, respectively. Patients with CD44-positive expression at the invasive tumour front had significantly poorer disease-specific survival than those with negative expression (CD44s: P<0.00001, CD44v6: P=0.013, CD44v9: P=0.0002). CD44s expression at the invasive tumour front was an independent prognostic factor in resectable GC patients (hazard ratio=3.13; 95% confidence interval, 1.09–9.01; P=0.035) and was significantly associated with peritoneal (P<0.001), lymphatic (P<0.001), and haematogenous recurrences (P=0.008). In addition, the number of CD44 isoforms expressed in cancer cells at the invasive tumour front was associated with patient prognosis. No conventional clinicopathological factors were independently associated with CD44 expression at the invasive tumour front.

Conclusions:

CD44-positive cancer stem-like cells at the invasive tumour front indicate poor survival and can be a unique biological prognostic factor for GC.

Clinicopathological and prognostic significance of cancer stem cell markers CD44 and CD133 in patients with gastric cancer: A comprehensive meta-analysis with 4729 patients involved

BACKGROUND

In recent years, CD44 and CD133 have been identified as 2 common used cancer stem cell (CSC) markers in gastric cancer. However, the clinicopathological and prognostic value of these markers in gastric cancer remains controversial; moreover, there is lack of comparison of these 2 markers' roles in clinical applications. A systematic review and meta-analysis was conducted to elucidate these markers' clinicopathological features and association with prognosis in patients with gastric cancer.

METHODS

Eligible studies were identified and odds ratios (ORs), hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated. Heterogeneity and sensitivity were analyzed as well. Publication bias was assessed using funnel plots and Egger tests.

RESULTS

The meta-analysis included 26 studies involving 4729 patients. High expression of CD44 was associated with Lauren type (intestinal type) (OR, 1.53 [95% CI, 1.02-2.30]; P = 0.038) and lymphatic vessel invasion (OR, 1.36 [95% CI, 1.06-1.76]; P = 0.021). CD133 overexpression was related to high TNM stage (III/IV) (OR, 3.18 [95% CI, 2.48-4.07]; P = 0.000), high depth of invasion (T3/T4) (OR, 2.97 [95% CI, 2.20-4.03]; P = 0.000), lymph node metastasis (OR, 2.82 [95% CI, 2.16-3.69]; P = 0.000), vascular invasion (OR, 6.71 [95% CI, 1.63-27.63]; P = 0.008), and distant metastasis (OR, 2.32 [95% CI, 1.64-3.29]; P = 0.000). In addition, survival analysis demonstrated a significant association between CD44, as well as CD133 and poor 5-year overall survival (HR, 1.87 [95% CI, 1.55-2.26]; P = 0.000; HR, 2.07 [95% CI, 1.76-2.44]; P = 0.000, respectively).

CONCLUSION

These data suggest that upregulated expression of CD44 and CD133 correlates with several clinicopathological features and poor prognosis. Since the related features do not overlap, combined detection of CD44 and CD133 expression can be an especially effective tool for pathological diagnosis and prognostic prediction of gastric cancer patients in clinical applications.

CD24 genetic variants contribute to overall survival in patients with gastric cancer

AIM

To investigate the role of single nucleotide polymorphisms (SNPs) in CD24 gene in susceptibility and overall survival of gastric cancer (GC).

METHODS

We genotyped 3 tagging SNPs of CD24-P-534 in the promoter region, P170 in the coding region of exon 2 and P1527 in the 3' untranslated region - using polymerase chain reaction-restriction fragment length polymorphism in specimens from 679 histologically-confirmed GC cases, 111 gastric atrophy (GA) cases and 976 tumor-free controls. Serum immunoglobulin G antibodies to Helicobacter pylori (H. pylori) of all subjects were detected by enzyme-linked immunosorbent assay. CD24 expression was evaluated by immunohistochemistry in 131 GC specimens. Correlations between SNPs and risk of GC or GA were shown by P values and odd ratios (ORs) with 95% confidence intervals (95%CI) compared with the most common genotype of each SNP using the unconditional logistic regression model after adjusting for age, sex and H. pylori infection. Survival within each SNP group was plotted by Kaplan-Meier method and compared by log-rank test (recessive model). Hazard ratios with 95%CIs were computed by Cox regression model after adjusting for age, sex, histological type, tumor differentiation, clinical stage and post-operational chemotherapy.

RESULTS

All of the three loci were in Hardy-Weinberg equilibrium in the control group. Median follow-up time for the 600 GC patients included in the survival analysis was 36.2 mo (range, 2.1-66.7 mo; 95%CI: 34.3-36.5 mo). Patients with the P-534 A/A genotype had significantly shorter survival (HR = 1.38, 95%CI: 1.01-1.88, P = 0.042) than did the C/C or C/A genotype carriers after adjusting for age, sex, histological type, tumor differentiation, clinical stage and post-operational chemotherapy. This trend was more evident in patients who lived longer than 2.5 years (HR = 7.55, 95%CI: 2.16-26.32, P = 0.001). The P170 T/T genotype was associated with a shorter lifespan than the non-T/T genotypes, but not significantly so. None of the three genetic variants was found to be associated with risk of GC (including tumor stage, grade and distant metastasis) or with risk of gastric atrophy. Furthermore, no difference of CD24 expression was found among the genotypes.

CONCLUSION

The P-534 site in CD24 gene affects the overall survival of gastric cancer and may serve as a prognostic marker for gastric cancer.

Concise Review: Emerging Role of CD44 in Cancer Stem Cells: A Promising Biomarker and Therapeutic Target

The reception and integration of the plethora of signals a cell receives from its microenvironment determines the cell's fate. CD44 functions as a receptor for hyaluronan and many other extracellular matrix components, as well as a cofactor for growth factors and cytokines, and thus, CD44 is a signaling platform that integrates cellular microenvironmental cues with growth factor and cytokine signals and transduces signals to membrane-associated cytoskeletal proteins or to the nucleus to regulate a variety of gene expression levels related to cell-matrix adhesion, cell migration, proliferation, differentiation, and survival. Accumulating evidence indicates that CD44, especially CD44v isoforms, are cancer stem cell (CSC) markers and critical players in regulating the properties of CSCs, including self-renewal, tumor initiation, metastasis, and chemoradioresistance. Furthermore, there is ample evidence that CD44, especially CD44v isoforms, are valuable prognostic markers in various types of tumors. Therefore, therapies that target CD44 may destroy the CSC population, and this holds great promise for the cure of life-threatening cancers. However, many challenges remain to determining how best to use CD44 as a biomarker and therapeutic target. Here we summarize the current findings concerning the critical role of CD44/CD44v in the regulation of cancer stemness and the research status of CD44/CD44v as biomarkers and therapeutic targets in cancer. We also discuss the current challenges and future directions that may lead to the best use of CD44/CD44v for clinical applications.

SIGNIFICANCE

Mounting evidence indicates that cancer stem cells (CSCs) are mainly responsible for cancer aggressiveness, drug resistance, and tumor relapse. CD44, especially CD44v isoforms, have been identified as CSC surface markers for isolating and enriching CSCs in different types of cancers. The current findings concerning the critical role of CD44/CD44v in regulation of cancer stemness and the research status of CD44/CD44v as biomarkers and therapeutic targets in cancer are summarized. The current challenges and future directions that may lead to best use of CD44/CD44v for clinical applications are also discussed.