Expression of CD44 isoforms in squamous cell carcinoma of the border of the tongue: A correlation with histological grade, pattern of stromal invasion, and cell differentiation

Expression of CD44 in Head and Neck Squamous Cell Carcinoma-An In-Silico Study

Introduction  CD44, a multistructural and multifunctional transmembrane glycoprotein, is a promising cancer stem cell (CSC) marker that regulates the properties of CSCs, including self-renewal, tumor initiation, and metastasis, and confers resistance to chemotherapy and radiotherapy. The aim of the present study was to evaluate the gene and protein expression of CD44 and explore its prognostic value in head and neck squamous cell carcinoma (HNSCC). Methodology  The present observational study employs computational tools for analysis. The Cancer Genome Atlas Head-Neck Squamous Cell Carcinoma dataset (520 primary HNSCC and 44 normal tissues) from the University of Alabama at Birmingham Cancer platform was used to study the association of CD44 mRNA transcript levels with various clinicopathological characteristics of HNSCC including age, gender, tumor grade, tumor stage, human papillomavirus (HPV) status, p53 mutation status, and overall survival. The CD44 protein expression in HNSCC and normal tissues was ascertained using the National Cancer Institute's Clinical Proteomic Tumor Analysis Consortium Head-and-Neck cancer dataset (108 primary HNSCC and 71 normal tissues). Results  CD44 mRNA transcript and protein expression levels were significantly higher in HNSCC tissues than in normal tissues, and high CD44 expression was correlated with poor survival. CD44 was upregulated in Stage 1 and Grade 2 HNSCC compared with other stages and grades. Overexpression of CD44 was observed in HPV-negative and TP53-positive mutant status in HNSCC. Conclusion  The pleiotropic roles of CD44 in tumorigenesis urge the need to explore its differential expression in HNSCC. The study concludes that CD44 can be a potential diagnostic and prognostic biomarker for HNSCC and offer new molecular targets for CD44-targeted therapy for cancer management.

Development of head and neck pathology in Europe

This review gives a brief history of the development of head and neck pathology in Europe from a humble beginning in the 1930s to the explosive activities the last 15 years. During the decades before the introduction of immunohistochemistry in the 1980s, head and neck pathology grew as a subspeciality in many European countries. In the late 1940s, the Institute of Laryngology and Otology with its own pathology laboratory was founded in London, and in 1964 the World Health Organization (WHO) International Reference Centre for the Histological Classification of Salivary Tumours was established at the Bland-Sutton Institute of Pathology, also in London. International collaboration, and very much so in Europe, led to the publication of the first WHO Classification of Salivary Gland Tumours in 1972. In the 1960s, a salivary gland register was organised in Hamburg and in Cologne the microlaryngoscopy was invented enabling microscopic endoscopic examination and rather shortly afterwards a carbon dioxide laser attached to the microscope became established and laryngeal lesions could be treated by laser vaporisation. During the last three decades, the use of immunohistochemistry supplemented with cytogenetic and refined molecular techniques has greatly facilitated the pathological diagnostics of head and neck lesions and has had a huge impact on research. Collaboration between different European centres has drastically increased partly due to establishment of scientific societies such as the Head and Neck Working Group (HNWG) within the European Society of Pathology and the International Head and Neck Scientific Group (IHNSG). A very large number of European pathologists have contributed to the 2nd, 3rd and 4th WHO books, and are involved in the upcoming 5th edition. Accredited educational meetings and courses are nowadays regularly arranged in Europe. Numerous textbooks on head and neck pathology have been written and edited by European pathologists. The increased collaboration has created larger series of tumours for research and new entities, mainly defined by their genetic abnormalities, are continuously emerging from Europe, particularly regarding salivary gland neoplasms and "undifferentiated" sinonasal tumours. These findings have led to a better and more precise classification and open the possibilities for new treatment strategies.

Cancer Stem Cell Markers, CD44 and ALDH1, for Assessment of Cancer Risk in OPMDs and Lymph Node Metastasis in Oral Squamous Cell Carcinoma

Tumour heterogeneity in oral cancer is attributed to the presence of cancer stem cells (CSCs). CSCs are the most migratory and metastatic cellular subpopulation within tumours. Assessment of CSC markers as significant predictors of lymph node metastasis may prove valuable in the clinical setting. Furthermore, analysis of this panel of putative stem cell markers in oral dysplasia may additionally inform of the likelihood for oral potentially malignant disorders (OPMDs) to progress to oral squamous cell carcinoma (OSCC). The present study aims to assess the significance of CSC markers in the progression of OPMDs to OSCC and assessment of lymph node metastasis in OSCC. CD44 and ALDH1 were assessed immunohistochemically in 25 normal, 30 OPMDs, and 24 OSCCs. CD44 is a membranous marker and ALDH1 is a cytoplasmic marker. The immunohistochemical expression of these markers were compared between OPMDs with and without dysplasia, as well as between low-risk and high-risk dysplasias. Similarly, expression was compared between OSCC with and without lymph node metastasis and among grades of OSCC. Positive CD44 expression was seen in all normal mucosal tissues. The expression decreased from normal epithelium to OPMDs but increased in OSCC. CD44 expression was positive in 21 cases of OSCC (87.5%) and reduced from well-differentiated to poorly differentiated OSCC. CD44 staining index was higher in OSCC without lymph node metastasis (3.59) when compared with OSCC with lymph node metastasis (1.33). There was a statistically significant difference observed in the ALDH1 staining index among three groups (p < 0.05), with highest expression seen in OSCC. Within OPMDs, the ALDH1 staining index was statistically higher in OPMDs with dysplasia as compared to OPMDs without dysplasia. Furthermore, the expression was higher in OPMDs with high-risk dysplasia when compared with low-risk dysplasia, but this was not statistically significant (p = 0.82). In conclusion, The CD44 positive population possesses properties of CSCs in head and neck carcinoma, and continuous shedding could be found after CD44 down-regulation. The present study reports differences in ALDH1 expression between OPMDs with and without dysplasia, dysplastic and non-dysplastic epithelia, and low-risk and high-risk dysplasia. These findings may suggest ALDH1 as a specific marker for dysplasia. CD44 demonstrated a difference in staining index in OSCC without lymph node metastasis versus OSCC with lymph node metastasis. These findings may suggest CD44 as a marker for lymph node metastasis. Both proteins may play key roles in the tumorigenicity of CSCs in OPMDs and OSCC.

Clinicopathological correlation of stem cell markers expression in oral squamous cell carcinoma; relation to patients` outcome

Background: Squamous cell carcinoma (OSCC) is the commonest oral malignancy.The overall 5 year survival of OSCC has remained at 50%, largely unchanged for 40 years. CSCs are important within the development, invasion, drug resistance, and prediction of carcinomas treatment outcome. ALDH1 and CD44 are commonly used epithelial tumors cancer stem-like cells surface markers. Materials: Our study aimed to judge CD44 and ALDH1 immunohistochemical expressions in 44 cases of OSCC and relates the expression to patients' survival. Results: High CD44 & ALDH1 expressions were significantly expressed in variable histologic grades of OSCCs, large sized carcinomas, presence lymph vascular invasion, presence of nodal and distant metastasis, advanced TNM clinical stage, recurrence and death during follow up period (P ≤ 0.05). Reduced DFS and three years overall survival were significantly recorded in cases with high CD44 expression, and high ALDH1 expression (p < 0.05). CD44 & ALDH1 expressions, histologic grade, tumor size were the independent predictors of DFS and three years OS. Conclusion: CD44 and ALDH1 expressions are valuable prognostic factors in OSCC and could be well considered predictors for patients' 3 years OS and DFS.

New monoclonal antibodies that recognize an unglycosylated, conserved, extracellular region of CD44 in vitro and in vivo, and can block tumorigenesis

CD44 is a transmembrane glycoprotein that binds to hyaluronic acid, plays roles in a number of cellular processes and is expressed in a variety of cell types. It is up-regulated in stem cells and cancer. Anti-CD44 monoclonal antibodies affect cell motility and aggregation, and repress tumorigenesis and metastasis. Here we describe four new anti-CD44 monoclonal antibodies originating from B cells of a mouse injected with a plasmid expressing CD44 isoform 12. The four monoclonal antibodies bind to the terminal, extracellular, conserved domain of CD44 isoforms. Based on differences in western blot patterns of cancer cell lysates, the four anti-CD44 mAbs separated into three distinct categories that include P4G9, P3D2, and P3A7, and P3G4. Spot assay analysis with peptides generated in Escherichia coli support the conclusion that the monoclonal antibodies recognize unglycosylated sequences in the N-terminal conserved region between amino acid 21-220, and analyses with a peptide generated in human embryonic kidney 293 cells, demonstrate that these monoclonal antibodies bind to these peptides only after deglycosylation. Western blots with lysates from three cancer cell lines demonstrate that several CD44 isoforms are unglycosylated in the anti-CD44 target regions. The potential utility of the monoclonal antibodies in blocking tumorigenesis was tested by co-injection of cells of the breast cancer-derived tumorigenic cell line MDA-MB-231 with the anti-CD44 monoclonal antibody P3D2 into the mammary fat pads of mice. All five control mice injected with MDA-MB-231 cells plus anti-IgG formed palpable tumors, while only one of the six test mice injected with MDA-MB-231 cells plus P3D2 formed a tiny tumor, while the remaining five were tumor-free, indicating that the four anti-CD44 mAbs may be useful therapeutically.

The current markers of cancer stem cell in oral cancers

Head and neck cancer (HNC) constitute 5% of all reported cancers. Among all, the oral cavity cancer is the most frequent type of HNC which accounts for over half of HNC cases. Mouth cancer ranks the sixth leading cause of cancer-related mortality. Generally, conventional chemotherapy has shown success at decreasing relapse and metastasis rates and improves the overall prognosis. Recently, target therapy and targeted drug delivery systems have been introduced as promising treatments. The elimination of efficiency of current therapeutic strategies due to the spared cancer stem cells that cause chemotherapy resistance, relapse and metastasis. Inefficiency methodologies in the elimination of all cancer cells in the body are a major problem that remained to be resolved before to confront the new cancer therapies. Many studies imply to cancer stem cell markers as important agents for targeted anti-cancer as well as improving chemotherapy efficiencies. The potentials of targeted cancer therapy led us to search for novel markers in the mouth cancer stem cells especially in rare cancers. The aimed of this research was, first a comprehensive critical review of the previous studies on the markers of cancer stem cells in oral cancers including oral squamous cell carcinoma, salivary gland cancers, and to highlight the most common cancer stem cell markers which have potential to be exploited as indicators for the preneoplastic lesion malignancy, oral cancer progression, and/or treatment prognosis.

The Expression and Functional Significance of Vascular Endothelial-Cadherin, CD44, and Vimentin in Oral Squamous Cell Carcinoma

Objectives

Ninety percent of head and neck cancers are squamous cell carcinoma which develops in the oral cavity. Metastasis is the main causative factor for death in 90% of all cancer-related deaths and begins with the invasion of tumor cells through the walls of small blood vessels or lymph vessels. A growing body of evidence has shown that vasculogenic mimicry (VM) facilitates tumor growth and cancer metastasis. The current study aimed to present the role of vascular endothelial (VE)-cadherin, CD44, and vimentin in inducing VM and epithelial-mesenchymal transition (EMT) and to identify the cancer stem cell (CSC) niche in different grades of oral squamous cell carcinoma (OSCC).

Materials and Methods

A total of 63 OSCC samples (21 samples each grade) were collected from the archive of Pathology Department of Besat educational hospital, Hamadan, Iran, from 2000 to 2015. VE-cadherin, CD44, and vimentin/periodic acid-Schiff (PAS) double-staining were used to validate VM. VM was identified by the detection of PAS-positive loops surrounded by tumor cells. Chi-square test was used to examine the differences between the variables. Significant level was set at 0.05. Pearson's correlation was used to assess the co-localization of the markers.

Results

There were statistically significant differences between tumor grade and the expression levels of VE-cadherin, CD44, and vimentin (P = 0.000). In addition, significant differences were found between tumor grade and microvessel density (P = 0.000) and between tumor grade and VM (P = 0.000).

Conclusion

Our results may disclose a definite relationship between VE-cadherin, CD44 and vimentin expression levels, VM formation, EMT, CSCs, and microvessel count in OSCC samples. For this reason, it is suggested that VE-cadherin, CD44, and vimentin are related to angiogenesis and VM formation in OSCC, therefore, in tumor progression and metastasis. Recently, antitumor angiogenic therapies have been challenged. The presence of VM may explain the failure of antiangiogenic treatments.

Expression of stem cell markers in oral cavity and oropharynx squamous cell carcinoma

OBJECTIVES

The aim of this study was to analyze the expression of CD24, CD44, CD133, ALDH1, CD29 (integrin-β1), and Ki-67 in squamous cell carcinoma of the oral cavity and oropharynx.

STUDY DESIGN

Fifty-two tumors and 21 metastatic lymph nodes were evaluated by using immunohistochemistry.

RESULTS

Seven of 52 cases (13.5%) showed positive cytoplasmic staining of aldehyde dehydrogenase 1; integrin-β1 was expressed in 45 of 50 cases (90%); 30 of 52 cases (57.7%) had positive membranous staining of CD44; CD24 was expressed in 44 of 50 cases (88%); and three of 52 cases (5.8%) stained positively for membranous CD133. Median proliferation rate, measured by Ki-67, was 37.1% for tumors. Five-year cancer-specific survival rates for the CD44-negative and CD44-positive groups were 74% and 38%, respectively, although this difference did not reach statistical significance (P = .052).

CONCLUSIONS

Our study demonstrated the expression of putative stem cell markers in squamous cell carcinoma of the oral cavity and oropharynx, with participation of CD44-positive cells in association with poor survival outcome.

The Importance of CD44 as a Stem Cell Biomarker and Therapeutic Target in Cancer

CD44 is a cell surface HA-binding glycoprotein that is overexpressed to some extent by almost all tumors of epithelial origin and plays an important role in tumor initiation and metastasis. CD44 is a compelling marker for cancer stem cells of many solid malignancies. In addition, interaction of HA and CD44 promotes EGFR-mediated pathways, consequently leading to tumor cell growth, tumor cell migration, and chemotherapy resistance in solid cancers. Accumulating evidence indicates that major HA-CD44 signaling pathways involve a specific variant of CD44 isoforms; however, the particular variant almost certainly depends on the type of tumor cell and the stage of the cancer progression. Research to date suggests use of monoclonal antibodies against different CD44 variant isoforms and targeted inhibition of HA/CD44-mediated signaling combined with conventional radio/chemotherapy may be the most favorable therapeutic strategy for future treatments of advanced stage malignancies. Thus, this paper briefly focuses on the association of the major CD44 variant isoforms in cancer progression, the role of HA-CD44 interaction in oncogenic pathways, and strategies to target CD44-overexpressed tumor cells.

Prognostic significance of CD44v6, p63, podoplanin and MMP-9 in oral squamous cell carcinomas

OBJECTIVES

To analyse the expression of the CD44v6, p63, podoplanin and MMP-9, and their prognostic significance in patients with oral squamous cell carcinomas (OSCC).

MATERIAL AND METHODS

Immunohistochemistry technique was performed on 60 OSCC for detection of CD44v6, p63, podoplanin and MMP-9 proteins. Extent and intensity of staining were evaluated in tumour cells and were compared with patients' clinical-pathological characteristics and survival.

RESULTS

CD44v6 expression was detected at the membrane of tumour cells of 94% cases. Nuclear expression of p63 protein was present in 96.5%. Podoplanin was observed at the membrane of tumour cells of 94% cases. MMP-9 was found in the cytoplasm of tumour cells in 83.7% cases. A high level of expression (67%-89%) in all four proteins was noted. Podoplanin was associated with the expression of MMP-9 (P = 0.010) and both were associated with lymph node metastasis (P = 0.011 and P = 0.018, respectively). Co-expression of podoplanin/MMP-9 was an adverse independent prognostic factor for cancer-specific survival (P = 0.008) and recurrence-free survival (P = 0.042).

CONCLUSION

Podoplanin and MMP-9 together could contribute to tumour progression and dissemination of OSCC. Their combined overexpression showed an adverse effect on survival, suggesting that they could be regarded as important prognostic biomarkers in OSCC.

CD44v3+/CD24- cells possess cancer stem cell-like properties in human oral squamous cell carcinoma

Cancer stem cells (CSCs) or cancer stem cell-like cells (CSC-LCs) are a minority population of cells that relate to tumor progression, metastasis and drug resistance. To identify CSC-LCs in oral squamous cell carcinoma (OSCC), we used two OSCC cell lines, SAS and OSC20, and cell surface markers, CD44v3 and CD24. In addition, we examined CD44v3 and CD24 expression immunohistochemically and evaluated the relationship between the expression and clinicopathological parameters in 50 OSCC tissues. In SAS and OSC20, CD44v3+/CD24- cells showed a higher sphere forming ability than the other fractions, i.e., CD44v3+/CD24+, CD44v3-/CD24- and CD44v3-/CD24+ cells. The proportion of CD44v3+/CD24- cells in SAS and OSC20 was 10.7 and 24.1%, respectively. Regarding SAS, CD44v3+/CD24- cells also showed a higher drug resistance for CDDP, 5-FU and cetuximab and expressed higher mRNA levels of CSC property-related genes than the other cell fractions. The tumorigenicity of CD44v3+/CD24- cells was not significantly different from the other fractions in SAS. An immunohistochemical study revealed a significant correlation between CD44v3 expression in the invasive portion and lymph node metastasis. Kaplan Meier analysis revealed cases with CD44v3 expression in the invasive portion tended to show poor overall survival (OS) compared with those without CD44v3, and there was a significant difference in OS between CD44v3+/CD24- and CD44v3-/CD24- immunophenotypes in the invasive portion. In conclusion, the results suggest that the CD44v3+/CD24- cell population displays CSC-LC properties in a human OSCC cell line. Additionally, we present evidence that CD44v3 immunoexpression and CD44v3+/CD24- immunophenotypes could give prognostic information associated with unfavorable clinical outcomes.

Tumour-stroma crosstalk in the development of squamous cell carcinoma

Squamous cell carcinoma (SCC) represents one of the most frequently diagnosed tumours and contributes significant mortality worldwide. Recent deep sequencing of cancer genomes has identified common mutations in SCC arising across different tissues highlighting perturbation of squamous differentiation as a key event. At the same time significant data have been accumulating to show that common tumour-stroma interactions capable of driving disease progression are also evident when comparing SCC arising in different tissues. We and others have shown altered matrix composition surrounding SCC can promote tumour development. This review focuses on some of the emerging data with particular emphasis on SCC of head and neck and skin with discussion on the potential tumour suppressive properties of a normal microenvironment. Such data indicate that regardless of the extent and type of somatic mutation it is in fact the tumour context that defines metastatic progression.

Immunohistochemical study of CD44s expression in oral squamous cell carcinoma-its correlation with prognostic parameters

BACKGROUND AND OBJECTIVES

The study aims at the observation of the immunohistochemical expression of CD44s in Oral Squamous Cell Carcinoma (OSCC) and to correlate its expression with prognostic parameters.

MATERIALS AND METHODS

A total of 30 cases of OSCC, - 10 cases of each well differentiated (WD SCC), moderately differentiated (MD SCC) and poorly differentiated squamous cell carcinomas (PD SCC) were included in the study. The sections were subjected to immunohistochemical study using CD44s antigen marker. The degree of intensity and distribution of CD44s immunostaining was assessed and correlated with prognostic markers such as tumor stage (tumor size), tumor grade (Broder's histological grading), tumor site, tumor thickness (histological depth of invasion) and nodal status.

RESULTS

CD44s expression by tumor cells in OSCCs is statistically correlated with tumor grade i.e. Higher mean of CD44s immunoexpression was observed in WD SCC group (10.80 ± 3.97), followed by MD SCC group (5.90 ± 3.38) and PD SCC group showed least CD44s immunoexpression (3.70 ± 4.64). There was no statistical significance observed with respect to the other prognostic markers.

CONCLUSION

Based on these observations it can be suggested that the decrease in expression of CD44s in OSCC cells may be due to the reduced cell-to-cell and cell-to-matrix adhesion, resulting in easy detachment from the rigid constitution. Low expression of CD44s in OSCC tissues may be an indicator of tumor invasion and high metastatic potential.

Expression and association of CD44v6 with prognosis in T2-3N0M0 esophageal squamous cell carcinoma

AIM

To investigate the expression of CD44v6 in stage T2-3N0M0 esophageal squamous cell carcinoma (ESCC) and its prognostic significance.

METHODS

The expression of CD44v6 in a series of 227 ESCC specimens was evaluated by immunohistochemistry (IHC). A reproducible semiquantitative method which took both staining percentage and intensity into account was applied for IHC scoring, and receiver operating characteristic (ROC) curve analysis was utilized to select the cut-off score for high or low IHC reactivity. Then, the correlations of CD44v6 expression with clinicopathological features of patients and its prognostic relevance were determined.

RESULTS

In the present study, the proportion of low CD44v6 expression was found significantly lower in Grade 3 of ESCC, than that of Grade 1 and Grade 2 of ESCC. There are no significant correlations between CD44v6 expression and other clinicopathological parameters including gender, age, tumor size, tumor location, depth of invasion and pathological stage. The Kaplan-Meier survival curves showed that up-regulated expression of CD44v6 indicated a poorer post-operative survival for ESCC patients of stage T2-3N0M0 (P=0.009), especially for those with T2 lesions (P=0.044) or with stage IIB diseases (P=0.005). Multivariate analysis also confirmed that CD44v6 expression [relative risk, 1.639; 95% confidence interval (CI): 1.142-2.354, P=0.007] and depth of invasion (relative risk, 1.487; 95% CI: 1.063-2.080, P=0.020) were independent prognostic factors.

CONCLUSIONS

Elevated CD44v6 expression may be an adverse prognostic indicator for patients with stage T2-3N0M0 ESCC, especially for those with T2 lesions or stage IIB diseases.

Significance of CD44 expression in head and neck cancer: a systemic review and meta-analysis

BACKGROUND

CD44 has been reported to be involved with tumor growth and metastasis and has also been implicated as a CSC marker in head and neck squamous cell cancer (HNSCC). However, the prognostic value of CD44 still remains controversial; hence, we investigated the correlation between CD44 and the clinicopathological features of HNSCC by meta-analysis.

METHODS

A comprehensive search was performed using PubMed, ISI web of Science and China National Knowledge Infrastructure (CNKI) up to April 2013. Only studies with immunohistochemical staining of HNSCC were considered. Data on TNM classification, tumor grade, disease free survival and 3- or 5-year overall survival rate were extracted.

RESULTS

Thirty studies with 2102 patients met the inclusion criteria for the meta-analysis. Fifteen studies used anti-pan-CD44 antibody, 9 used anti-CD44-v6 antibody, 2 used anti-CD44-v3 and 2 used anti-CD44s antibody, 1 used anti-CD44-v9, and 1 used anti-CD44-v6,-v3 and -v4-5 simultaneously. The total percentage of CD44 expression was 57.8%, with 49.3% in oral cancer patients, 66.4% in pharynx and 54.7% in larynx cancer patients expressing CD44. No significant correlation between clinical features and CD44 expression was revealed for oral cancer patients, but CD44 was shown to be associated with advanced T categories (larynx: RR = 1.33, 95% CI 1.01-1.76; larynx & pharynx RR = 1.21, 95% CI 1.08-1.35), worse N categories (larynx: RR = 2.53, 95% CI 1.99-3.21; larynx & pharynx RR = 1.95, 95% CI 1.35-2.82), higher tumor grades (larynx & pharynx RR = 1.71, 95% CI 1.04-2.79) and 5-year OS rates (larynx: RR = 0.62, 95% CI 0.47-0.83; larynx & pharynx RR = 0.66, 95% CI 0.47-0.94) in patients with laryngeal and pharyngolaryngeal cancer. In stratified analysis, pan-CD44 and CD44-v6 expression were both correlated with 5-year OS rate of patients with laryngeal (CD44: RR = 0.66, 95% CI 0.46-0.95; CD44-v6 RR = 0.53, 95% CI 0.37-0.77) and pharyngolaryngeal cancer (CD44: RR = 0.56, 95% CI 0.34-0.93; CD44-v6 RR = 0.53, 95% CI 0.37-0.77).

CONCLUSIONS

Our analysis suggested that CD44 is related to worse T category, N category, tumor grade and prognosis, in pharyngeal and laryngeal cancer, but no clear association was revealed between CD44 expression and oral cancer.

Cancer stem cell characteristics, ALDH1 expression in the invasive front of nasopharyngeal carcinoma

The invasive tumor front underlies the biological aggressiveness and epithelial-mesenchymal transition (EMT) in various human malignances. However, the molecular and biological characteristics of invasive tumor front in NPC have rarely been described. Additionally, the features of cancer stem cells (CSCs) in the invasive front of tumors and its correlation with EMT also remain elusive. Our study was to investigate the expression of CSCs marker aldehyde dehydrogenase 1 (ALDH1) in the invasive front of nasopharyngeal carcinoma (NPC) and its clinical significance. Immunohistochemistry was mainly used to detect ALDH1 expression in the invasive front of NPC. The relationship between ALDH1 expression and EMT-associated markers was also examined. ALDH1 expression in the invasive front correlated strongly with lymphatic invasion (p<0.001), T classification (p=0.001), M classification (p<0.001), clinical stage (p<0.001), and local recurrence (p=0.008). ALDH1 overexpression in the invasive front contributed to worse survival of NPC, particularly in patients with early stage (T1-T2 or N0-N1) (p<0.001 and p=0.002, respectively), though it was not an independent prognostic factor (p=0.196). Furthermore, in the invasive front of NPC, ALDH1 expression correlated significantly with EMT-related biomarkers E-cadherin (p=0.026), Vimentin (p<0.001), Periostin (p<0.001), and Snail (p<0.001), but not with β-catenin (p=0.143). Our findings demonstrate first that ALDH1 expression in the invasive front links closely with EMT characteristics and tumor aggressiveness, which might provide a useful prognostic marker for NPC patients.

Cancer stem cells in head and neck cancer

Cancer stem cells (CSCs), also called “cells that start the tumor,” represent in themselves one of the most topical and controversial issues in the field of cancer research. Tumor stem cells are able to self-propagate in vitro (self-renewal), giving rise both to other tumor stem cells and most advanced cells in the line of differentiation (asymmetric division). A final characteristic is tumorigenicity, a fundamental property, which outlines the tumor stem cell as the only cell able to initiate the formation of a tumor when implanted in immune-deficient mice. The hypothesis of a hierarchical organization of tumor cells dates back more than 40 years, but only in 1997, thanks to the work of John Dick and Dominique Bonnet, was there the formal proof of such an organization in acute myeloid leukemia. Following this, many other research groups were able to isolate CSCs, by appropriate selection markers, in various malignancies, such as breast, brain, colon, pancreas, and liver cancers and in melanoma. To date, however, it is not possible to isolate stem cells from all types of neoplasia, particularly in solid tumors. From a therapeutic point of view, the concept of tumor stem cells implies a complete revision of conventional antineoplastic treatment. Conventional cytotoxic agents are designed to target actively proliferating cells. In the majority of cases, this is not sufficient to eliminate the CSCs, which thanks to their reduced proliferative activity and/or the presence of proteins capable of extruding chemotherapeutics from the cell are not targeted. Therefore, the theory of cancer stem cells can pose new paradigms in terms of cancer treatment. Potential approaches, even in the very early experimental stages, relate to the selective inhibition of pathways connected with self-renewal, or more specifically based on the presence of specific surface markers for selective cytotoxic agent vehicles. Finally, some research groups are trying to induce these cells to differentiate, thus making them easier to remove. For all these reasons, we have collected existing literature on head and neck cancer stem cells that correlate the biological characteristics of this subpopulation of cancer cells with the clinical behavior of tumors.

Role of CD44 as a marker of cancer stem cells in head and neck cancer

In recent years, many studies have shown that some types of tumors are characterized by the presence of cells with stem-like characteristics, called cancer stem cells (CSCs). These are considered cells that initiate the tumor and are probably responsible for tumor recurrence. CSCs have the capacity for self-renewal, the potential to give rise to one or more cell types within the tumor, and the ability to drive, in a continuous manner, the proliferation of malignant cells. The failure of current cancer therapies can be attributed to the relative ineffectiveness of drugs against CSCs, which remain viable while retaining their full ability to reproduce the tumor. The development of new strategies is currently hampered by the lack of reliable markers to identify CSCs. One promising surface marker of CSCs in head and neck cancer is the CD44 molecule, which has been shown in preliminary studies to have high specificity, although there are discrepant data because its prognostic value may depend on the specific tumor location. More rigorous studies are needed to investigate the usefulness of CD44 expression in head and neck tumors for possible clinical applicability.

CD44 expression in oro-pharyngeal carcinoma tissues and cell lines

Expression of CD44, a transmembrane hyaluronan-binding glycoprotein, is variably considered to have prognostic significance for different cancers, including oral squamous cell carcinoma. Although unclear at present, tissue-specific expression of particular isoforms of CD44 might underlie the different outcomes in currently available studies. We mined public transcriptomics databases for gene expression data on CD44, and analyzed normal, immortalized and tumour-derived human cell lines for splice variants of CD44 at both the transcript and protein levels. Bioinformatics readouts, from a total of more than 15,000 analyses, implied an increased CD44 expression in head and neck cancer, including increased expression levels relative to many normal and tumor tissue types. Also, meta-analysis of over 260 cell lines and over 4,000 tissue specimens of diverse origins indicated lower CD44 expression levels in cell lines compared to tissue. With minor exceptions, reverse transcribed polymerase chain reaction identified expression of the four main isoforms of CD44 in normal oral keratinocytes, transformed lines termed DT and HaCaT, and a series of paired primary and metastasis-derived cell lines from oral or pharyngeal carcinomas termed HN4/HN12, HN22/HN8 and HN30/HN31. Immunocytochemistry, Western blotting and flow cytometric assessments all confirmed the isoform expression pattern at the protein level. Overall, bioinformatic processing of large numbers of global gene expression analyses demonstrated elevated CD44 expression in head and neck cancer relative to other cancer types, and that the application of standard cell culture protocols might decrease CD44 expression. Additionally, the results show that the many variant CD44 exons are not fundamentally deregulated in a diverse range of cultured normal and transformed keratinocyte lines.

Cancer stem cells hypothesis and stem cells in head and neck cancers

There is increasing evidence that the growth and spread of cancer is driven by a small subpopulation of cancer cells, defined as cancer stem cells (CSCs). Recent data indicate that the initiation, growth, recurrence and metastasis of cancers are related to the behavior of a small population of malignant cells with properties of stem cells, and information about them are potentially helpful in identifying the target for the tumor's therapeutic elimination. The presence of subpopulation cells with phenotypic and behavioral characteristics corresponding to both normal epithelial stem cells and to cells capable of initiating tumors has been also reported in head and neck squamous cell carcinomas (HNSCCs).

Hyaluronic acid-paclitaxel conjugate inhibits growth of human squamous cell carcinomas of the head and neck via a hyaluronic acid-mediated mechanism

Chemotherapeutic regimens incorporating taxanes significantly improve outcomes for patients with squamous cell carcinomas of the head and neck (SCCHN). However, treatment with taxanes is limited by toxicities, including bone marrow suppression and peripheral neuropathies. We proposed that conjugating taxanes to targeting carrier molecules would increase antitumor efficacy and decrease toxicity. The cell surface proteoglycan, CD44, is expressed on most SCCHNs, and we hypothesized that it is an attractive candidate for targeted therapy via its natural ligand, hyaluronic acid (HA). We determined whether HA-paclitaxel conjugates were able to decrease tumor growth and improve survival in orthotopic nude mouse human SCCHN xenograft models. HA-paclitaxel concentration-dependent growth inhibition of human SCCHN cell lines OSC-19 and HN5 in vitro, very similarly to free paclitaxel treatment. Tumor cell uptake of FITC-labeled HA-paclitaxel was significantly blocked with free HA, indicating the dependence of uptake on CD44. HA-paclitaxel administered intravenously once per week for three weeks at 120 mg/kg paclitaxel equivalents, far above the paclitaxel maximum tolerated dose, exerted superior tumor growth control to that of paclitaxel in both orthotopic OSC-19-luciferase and HN5 xenograft models in vivo. Mouse survival following HA-paclitaxel administration was prolonged compared with that of controls in mice implanted with either of these xenografts. Mice treated with HA-paclitaxel displayed increased TUNEL(+) cells in tumor tissue, as well as markedly reduced microvessel density compared to those treated with free paclitaxel. No acute histopathological changes were observed in mice treated with HA-paclitaxel. Thus, we conclude that HA-paclitaxel effectively inhibits tumor growth in human SCCHN xenografts via an HA-mediated mechanism and this conjugate should be considered for further preclinical development for this disease.

CD44 variant isoforms in head and neck squamous cell carcinoma progression

OBJECTIVES/HYPOTHESIS

The CD44 family of receptors includes multiple variant isoforms, several of which have been linked to malignant properties including migration, invasion, and metastasis. The objective of this study was to investigate the role of the CD44 v3, v6, and v10 variant isoforms in head and neck squamous cell carcinoma (HNSCC) tumor progression behaviors.

STUDY DESIGN

Laboratory study involving cell cultures and clinical tissue specimens.

METHODS

Analysis of the expression of standard CD44s and the CD44 variant isoforms v3, v6, and v10 was carried out in the HNSCC cell line, HSC-3. The role of CD44 isoforms in migration, proliferation, and cisplatin resistance was determined. Immunohistochemical analysis was performed on clinical tissue specimens obtained from a series of 82 HNSCC patients. The expression of standard CD44s and the CD44 v3, v6, and v10 variants in primary tumor specimens (n = 82) and metastatic cervical lymph nodes (n = 24) were analyzed with respect to various clinicopathologic variables.

RESULTS

HSC-3 cells express at least four CD44 isoforms, and these CD44 isoforms mediate migration, proliferation, and cisplatin sensitivity. Compared with primary tumors, a greater proportion of metastatic lymph nodes demonstrated strong expression of CD44 v3 (lymph node 14/24 vs. primary tumor 38/82), CD44 v6 (lymph node 18/24 vs. primary tumor 26/82), and CD44 v10 (lymph node 14/24 vs. primary tumor 16/82), while expression of standard CD44 was not significantly different in metastatic lymph nodes and primary tumors (lymph node 10/24 vs. primary tumor 60/82). Expression of CD44 variant isoforms were associated with advanced T stage (v3 and v6), regional (v3) and distant (v10) metastasis, perineural invasion (v6), and radiation failure (v10). CD44 v6 and CD44 v10 were also significantly associated with shorter disease-free survival.

CONCLUSIONS

CD44 isoforms mediate migration, proliferation, and cisplatin sensitivity in HNSCC. Furthermore, expression of certain CD44 variants may be important molecular markers for HNSCC progression and should be investigated as potential therapeutic targets for therapy.

Association of CD44 V3-containing isoforms with tumor cell growth, migration, matrix metalloproteinase expression, and lymph node metastasis in head and neck cancer

BACKGROUND

The CD44 family of receptors includes multiple variant isoforms, some of which have been linked to tumor progression. The objective of this study was to investigate whether CD44 v3-containing isoforms are involved in head and neck squamous cell carcinoma (HNSCC) tumor progression.

METHODS

Laboratory investigation utilizing HNSCC cell lines and clinical tissue specimens was performed.

RESULTS

Investigation of 13 HNSCC cell lines revealed a diversity of CD44 isoform profiles, including expression of CD44 v3-containing isoforms. Two cell lines, HOC313 and MDA1483, were selected for further study based on their CD44 v3 expression profile. The HOC313 cell line, which highly expresses CD44 v3-containing isoforms, demonstrated hyaluronan-mediated CD44-dependent promotion of tumor cell growth and migration. Conditioned media from the HOC313 cell line also exhibited high matrix metalloproteinase expression on gelatin zymography. Immunohistochemical analysis of a series of metastatic HNSCC lymph nodes revealed CD44 overexpression as well as staining for CD44 v3-containing isoforms.

CONCLUSION

CD44 v3-containing isoforms are associated with HNSCC growth, migration, and matrix metalloproteinase activity and can be identified in lymph node metastasis.

ADAM-17 associated with CD44 cleavage and metastasis in oral squamous cell carcinoma

ADAM-17 (a disintegrin and metalloproteinase 17) is a membrane-anchored protein, which can cleave the ectodomain in a variety of transmembrane proteins. In the in vitro experiments with tumor cells, ADAM-17 is reported to cleave CD44, an adhesion molecule that interacts with hyaluronic acid, to promote tumor cell migration. In the present study, we examined ADAM-17 expression and CD44 cleavage in specimens from 50 patients diagnosed to have oral squamous cell carcinoma (SCC). Each specimen was divided into two pieces, one was studied by immunohistochemistry and the other was subjected to a Western blot. By coordinating the results of both analyses, ADAM-17 expression was evaluated to be high in 23 cases (46%). When CD44 cleavage was also studied by immunohistochemical staining as well as with Western blotting, CD44 cleavage was judged to be positive in 29 cases (58%). When the ADAM-17 expression level was compared with the CD44 cleavage state, most of the cases expressing high levels of ADAM-17 (87%) showed positive CD44 cleavage. The level of ADAM-17 expression was significantly correlated to the nodal metastasis and local recurrence in oral SCC. Our findings suggest that ADAM-17 is involved in CD44 cleavage and contributes to tumor progression in oral SCC.

CD44 expression and its relationship with MMP-9, clinicopathological factors and survival in oral squamous cell carcinoma

We investigated the expression of CD44 and MMP-9 in primary oral squamous cell carcinoma (OSCC) and evaluated their association with each other and clinicopathological factors as well as their prognostic value during long term follow up. Histological samples from 138 OSCC patients were immunohistochemically stained for the expression of CD44 and MMP-9. The staining results were compared with conventional prognostic factors and their impacts to patients' prognosis were also studied with survival analyses. Irregular staining of CD44 in tumour cells was associated with poor tumour differentiation (p=0.003), higher clinical stage (III-IV) (p=0.049), and the presence of T3-4 tumour stage (p=0.03). Strong stromal MMP-9 staining intensity was correlated with poor tumour differentiation (p=0.03). In univariate survival analysis irregular staining of CD44 in tumour cells was related to poor disease free and overall survival (p=0.001 and p<0.001, respectively). In multivariate analysis CD44 staining was a significant independent predictor for overall (p=0.03) and disease free survival (p=0.003). MMP-9 expression showed no statistical significance in survival analyses. Strong stromal staining intensity of MMP-9 correlated with irregular staining of CD44 in tumour cells, but had no prognostic significance in the present cohort. However, irregular staining of CD44 predicted more advanced disease and shortened survival of the patients.

Adhesion molecule CD44 expression in non-tumour epithelium adjacent to tongue cancer

An immunohistochemical study was performed of changes in the expression of adhesion molecule CD44 in 32 adjacent non-tumour epithelia (ANTE) to lingual carcinomas and in the tumour tissue, using anti-CD44 monoclonal antibody DF1485. The aim was to evaluate the importance of these changes as an early event in lingual carcinogenesis. The ANTE was histologically normal in 22 cases (68.8%) and presented epithelial dysplasia in 10 (32.2%). Three cases of normal and dysplastic ANTE, respectively, were CD44- (9.4%). Negative CD44 expression was significantly more frequent in tumours with lower percentages of CD44+ cancer cells, both in normal (P=0.014) and dysplastic (P=0.033) ANTE. The expression in normal ANTE was also significantly associated with clinical stage (P=0.040) and presence of extracapsular nodal spread (P=0.013). Therefore, loss of CD44 expression in ANTE can be considered an early event in lingual carcinogenesis and a marker of major alterations of CD44 expression in the derived tumour tissue.

Significance of immunohistochemical over-expression of CD44v6 as an indicator of malignant potential in esophageal squamous cell carcinoma

PURPOSE

The aim of the current study was to find out a clinicopathologic significance of CD44v6 over-expression in esophageal squamous cell carcinoma (ESCC), which has not been elucidated fully.

METHODS

Immunohistochemical expression of CD44v6 was examined for 81 ESCCs. Correlation of CD44 over-expression with the clinicopathologic features were investigated.

RESULTS

Thirty-eight ESCCs (46.9%) had over-expression of CD44v6. The proportions of the incidence of lymph node metastasis (P=0.039), lymphatic permeation (P=0.003), and blood vessel invasion (P=0.037) in ESCCs with over-expression of CD44v6 were significantly higher than those in ESCCs without over-expression of CD44v6. The stage of the tumor in ESCCs with over-expression of CD44v6 was significantly more advanced (P=0.045). Survival rates of patients with ESCC with over-expression of CD44v6 were significantly worse (P=0.0005). Moreover, CD44v6 over-expression (P=0.048) as well as blood vessel invasion (P=0.014) and stage of the tumor ( P=0.010) were factors independently associated with the unfavorable prognosis of the patients with ESCC.

CONCLUSIONS

Over-expression of CD44v6 can be an indicator of the malignant potential of ESCC.

The role of the CD44/ezrin complex in cancer metastasis

CD44 is a cell adhesion molecule that was traditionally known as 'homing receptor'. This molecule is known to interact with the ezrin family (ERM family) members and form a complex that plays diverse roles within both normal and abnormal cells, particularly cancer cells. CD44 and ezrin and their respective complex have properties suggesting that they may be important in the process of tumour-endothelium interactions, cell migrations, cell adhesion, tumour progression and metastasis. This article reviews the role of CD44, ezrin family and the CD44/ezrin complex in cancer cells and their clinical impact in patients with cancer.

Gains and losses of adhesion molecules (CD44, E-cadherin, and beta-catenin) during oral carcinogenesis and tumour progression

The aim of this study was to define whether or not the impaired expression of CD44, E-cadherin (E-cad), and beta-catenin (beta-cat) correlates with the clinical evolution and prognosis of oral cancer. Ninety-three primary oral squamous cell carcinomas (OSCCs) with tumour-adjacent normal and/or dysplastic mucosa, 30 associated metastases, and 12 recurrences were immunostained for CD44s, -v3, -v4, -v5, -v6, -v7, -v9, E-cad, and beta-cat. In non-neoplastic epithelium, all molecules investigated were constitutively expressed in the basal layers. In the majority of dysplasias, immunoreactivity for all adhesion molecules was increased, but there was restricted loss for CD44s, E-cad, and beta-cat in a few cases. In carcinomas, a striking accumulation of CD44s, v3, v4, v9 and a loss of E-cad/beta-cat were observed at the invasive tumour front. In metastases and recurrences, besides a loss of CD44s, v4, v7, and E-cad, a significant increase of v9 was recorded, whereas CD44v5 and v6 remained unchanged. Clinically, reduced expression of CD44v3, E-cad, and changes of CD44v9 phenotype within the primary tumours correlated significantly with poor prognosis; decreased beta-cat expression was a predictive marker for nodal metastases. These findings indicate that there is some perturbed expression of adhesion molecules during the stepwise course of oral carcinogenesis and tumour progression. Distinct phenotypic alterations project poor prognosis, while others predict metastasis. Some of these restricted molecular changes may serve as potential targets for future antibody-based tumour therapy.

The prognostic value of immunohistochemically detected CD44v3 and CD44v6 expression in patients with surgically staged vulvar carcinoma: a multicenter study

BACKGROUND

Isoforms of the adhesion molecule CD44 are involved in carcinogenesis and the metastatic cascade of tumor cells by increasing the affinity of malignant cells to their extracellular matrix. Preliminary data with respect to the prognostic value of the CD44 isoforms CD44v3 and CD44v6 in patients with vulvar carcinoma showed promising results. The current multicenter study aimed to determine the prognostic value of CD44v3 and CD44v6 in patients with surgically staged vulvar carcinoma.

METHODS

Expression of CD44v3 and CD44v6 in vulvar carcinoma tissue was assessed by immunohistochemistry. Immunohistochemical staining was performed according to established protocols. Results were correlated to clinical data.

RESULTS

A positive CD44v3 and CD44v6 staining was detected in 33.3% (33 out of 99) and 39.4% (39 out of 99) of the tumor samples, respectively. Overexpression of CD44v6 was associated with an impaired prognosis with respect to disease-free survival (P = 0.01) and overall survival (P = 0.04). Multivariate analysis showed that CD44v6 provided prognostic information with respect to disease-free survival (P = 0.001) and overall survival (P = 0.005) independently of the two established prognosticators, tumor stage and groin lymph node involvement. Overexpression of CD44v3 had no impact on patient survival.

CONCLUSIONS

The current multicenter study, involving a large series of patients with surgically staged vulvar carcinoma, allowed for multivariate survival analysis and showed that CD44v6 confers prognostic information in addition to that provided by the established clinicopathologic parameters of tumor stage and lymph node status.