Immunohistochemical study of desmosomes in oral squamous cell carcinoma: correlation with cytokeratin and E-cadherin staining, and with tumour behaviour

Paradoxical Roles of Desmosomal Components in Head and Neck Cancer

Desmosomes are intercellular adhesion complexes involved in various aspects of epithelial pathophysiology, including tissue homeostasis, morphogenesis, and disease development. Recent studies have reported that the abnormal expression of various desmosomal components correlates with tumor progression and poor survival. In addition, desmosomes have been shown to act as a signaling platform to regulate the proliferation, invasion, migration, morphogenesis, and apoptosis of cancer cells. The occurrence and progression of head and neck cancer (HNC) is accompanied by abnormal expression of desmosomal components and loss of desmosome structure. However, the role of desmosomal components in the progression of HNC remains controversial. This review aims to provide an overview of recent developments showing the paradoxical roles of desmosomal components in tumor suppression and promotion. It offers valuable insights for HNC diagnosis and therapeutics development.

A six-gene expression signature related to angiolymphatic invasion is associated with poor survival in laryngeal squamous cell carcinoma

Purpose

Angiolymphatic invasion serves as a histopathological risk factor for unfavorable survival in head and neck squamous cell carinoma. The aim of the study was to explore  the molecular mechanisms characterizing angiolymphatic invasion and therefore identify a gene expression signature related to angiolymphatic invasion.

Methods

Gene expression analysis of head and neck squamous cell carcinoma was carried out based on clinical and whole genome expression data provided by The Cancer Genome Atlas. Results were validated in an independent cohort of laryngeal squamous cell carcinoma and confirmed by immunohistochemistry staining.

Results

A gene expression signature consisting of six genes (SHH, SLC18A3, LCE3E, LCE2B, LCE3D and DSG-1) related to angiolymphatic invasion was identified. The gene expression profile identified a subset of patients with decreased overall survival (p = 0.02, log rank test), which was most prominent for patients with laryngeal squamous cell carcinoma (p = 0.004, log rank test). Furthermore, these patients showed a significant shorter progression-free survival (p = 0.002, log rank test). By use of this gene expression signature, patients at high risk of recurrence could be identified even if morphological changes were not yet recognizable.

Conclusion

Angiolymphatic invasion is characterized by a distinct histopathological phenotype and specific gene expression signature. The newly identified signature might serve as a reliable predictor of outcome in laryngeal cancer and add additional benefit to histopathological evaluation.

Electronic supplementary material

The online version of this article (10.1007/s00405-020-06214-1) contains supplementary material, which is available to authorized users.

Role of E-cadherin and cyclin D1 as predictive markers of aggression and clonal expansion in head and neck squamous cell carcinoma

Objectives

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide. Inconsistency in various histopathologic features for predicting nodal metastasis and overall prognosis and a better understanding of molecular mechanisms of tumourigenesis have shifted the focus to a search for more definitive predictive markers. To identify the role of two immunohistochemical (IHC) markers, E-cadherin and cyclin D1, as predictive markers of aggressiveness in HNSCC and to assess clonal expansion of tumour cells.

Materials and Methods

A total of 66 cases of HNSCC with neck node dissection were studied. IHC was performed on primary tumour sections and lymph nodes showing metastatic deposits. Histopathological parameters such as tumour grade and TNM stage together with nodal status were compared according to expression of the two markers. Fischer's chi-square test was used to assess the correlation between the two markers and histopathological parameters.

Results

Out of 66 cases studied, 37 showed LN metastasis. Most of the patients were male, and the most common tumour site was buccal mucosa. We found a significant association between loss of E-cadherin and node metastasis (P<0.001) and higher TNM stage (P<0.001). Cyclin D1 overexpression was significantly associated with only nodal metastasis (P=0.007). No significant association with tumour grade was found for either marker. The subgroup of E-cadherin loss with cyclin D1 overexpression was associated with the maximum incidence of nodal metastasis and higher TNM stage, highlighting the importance of using a combination of these two markers. A significant association was noted between the expression of markers at the primary site and at nodal deposits, indicating clonal expansion.

Conclusion

A combination of the two markers E-cadherin and cyclin D1 can predict prognosis in HNSCC, although tumour heterogeneity may affect this association in some cases.

Impact of Storage Temperature on the Expression of Cell Survival Genes in Cultured ARPE-19 Cells

PURPOSE

The development of a suitable storage method for retinal pigment epithelium (RPE) is necessary in the establishment of future RPE replacement therapy, and storage temperature has proven to be pivotal for cell survival. ARPE-19, a widely used model for RPE, has been shown to yield the greatest number of viable cells when stored at 16°C compared to other storage temperatures. In this study, we analyze the gene expression profile of cultured ARPE-19 cells after seven days of storage at different temperatures in an effort to predict the gene-level consequences of storage of RPE transplants.

MATERIALS AND METHODS

ARPE-19 cells were cultured until confluence and then stored in minimum essential medium at 4°C, 16°C, and 37°C for seven days. The total RNA was isolated and the gene expression profile was determined using DNA microarrays. The Results were validated using qPCR.

RESULTS

Principal component and hierarchical clustering analyses show that the gene expression profiles of cell cultures stored at different temperatures cluster into separate groups. Cultures stored at 4°C cluster closest to the control cultures that were not stored and display the least change in gene expression after storage (157 differentially expressed genes). Cultures stored at 16°C and 37°C display a much larger change in differential gene expression (1787 and 1357 differentially expressed genes, respectively). At 16°C, the expression of several genes with proposed tumor suppressor functions was markedly increased. Changes in regulation of several known signaling pathways and of oxidative stress markers were discovered at both 16°C and 37°C, and activation of the angiogenesis marker vascular endothelial growth factor (VEGF) was discovered at 37°C. There was no evidence of the activation of inflammatory processes in stored cell cultures.

CONCLUSION

ARPE-19 cultures stored at 16°C show the greatest propensity to modulate their gene expression profile in a manner that supports cell survival during storage.

Storage Temperature Alters the Expression of Differentiation-Related Genes in Cultured Oral Keratinocytes

Purpose

Storage of cultured human oral keratinocytes (HOK) allows for transportation of cultured transplants to eye clinics worldwide. In a previous study, one-week storage of cultured HOK was found to be superior with regard to viability and morphology at 12°C compared to 4°C and 37°C. To understand more of how storage temperature affects cell phenotype, gene expression of HOK before and after storage at 4°C, 12°C, and 37°C was assessed.

Materials and Methods

Cultured HOK were stored in HEPES- and sodium bicarbonate-buffered Minimum Essential Medium at 4°C, 12°C, and 37°C for one week. Total RNA was isolated and the gene expression profile was determined using DNA microarrays and analyzed with Partek Genomics Suite software and Ingenuity Pathway Analysis. Differentially expressed genes (fold change > 1.5 and P < 0.05) were identified by one-way ANOVA. Key genes were validated using qPCR.

Results

Gene expression of cultures stored at 4°C and 12°C clustered close to the unstored control cultures. Cultures stored at 37°C displayed substantial change in gene expression compared to the other groups. In comparison with 12°C, 2,981 genes were differentially expressed at 37°C. In contrast, only 67 genes were differentially expressed between the unstored control and the cells stored at 12°C. The 12°C and 37°C culture groups differed most significantly with regard to the expression of differentiation markers. The Hedgehog signaling pathway was significantly downregulated at 37°C compared to 12°C.

Conclusion

HOK cultures stored at 37°C showed considerably larger changes in gene expression compared to unstored cells than cultured HOK stored at 4°C and 12°C. The changes observed at 37°C consisted of differentiation of the cells towards a squamous epithelium-specific phenotype. Storing cultured ocular surface transplants at 37°C is therefore not recommended. This is particularly interesting as 37°C is the standard incubation temperature used for cell culture.

Gene expression and splicing alterations analyzed by high throughput RNA sequencing of chronic lymphocytic leukemia specimens

Background

To determine differentially expressed and spliced RNA transcripts in chronic lymphocytic leukemia specimens a high throughput RNA-sequencing (HTS RNA-seq) analysis was performed.

Methods

Ten CLL specimens and five normal peripheral blood CD19+ B cells were analyzed by HTS RNA-seq. The library preparation was performed with Illumina TrueSeq RNA kit and analyzed by Illumina HiSeq 2000 sequencing system.

Results

An average of 48.5 million reads for B cells, and 50.6 million reads for CLL specimens were obtained with 10396 and 10448 assembled transcripts for normal B cells and primary CLL specimens respectively. With the Cuffdiff analysis, 2091 differentially expressed genes (DEG) between B cells and CLL specimens based on FPKM (fragments per kilobase of transcript per million reads and false discovery rate, FDR q < 0.05, fold change >2) were identified. Expression of selected DEGs (n = 32) with up regulated and down regulated expression in CLL from RNA-seq data were also analyzed by qRT-PCR in a test cohort of CLL specimens. Even though there was a variation in fold expression of DEG genes between RNA-seq and qRT-PCR; more than 90 % of analyzed genes were validated by qRT-PCR analysis. Analysis of RNA-seq data for splicing alterations in CLL and B cells was performed by Multivariate Analysis of Transcript Splicing (MATS analysis). Skipped exon was the most frequent splicing alteration in CLL specimens with 128 significant events (P-value <0.05, minimum inclusion level difference >0.1).

Conclusion

The RNA-seq analysis of CLL specimens identifies novel DEG and alternatively spliced genes that are potential prognostic markers and therapeutic targets. High level of validation by qRT-PCR for a number of DEG genes supports the accuracy of this analysis. Global comparison of transcriptomes of B cells, IGVH non-mutated CLL (U-CLL) and mutated CLL specimens (M-CLL) with multidimensional scaling analysis was able to segregate CLL and B cell transcriptomes but the M-CLL and U-CLL transcriptomes were indistinguishable. The analysis of HTS RNA-seq data to identify alternative splicing events and other genetic abnormalities specific to CLL is an added advantage of RNA-seq that is not feasible with other genome wide analysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1708-9) contains supplementary material, which is available to authorized users.

Expression of E-cadherin in normal oral mucosa, in oral precancerous lesions and in oral carcinomas

Objective:

The aim of the present study was to assess the expression of E-cad in oral precancerous lesions and conditions and oral carcinomas in comparison with normal mucosa.

Materials and Methods:

Total of 50 samples were selected for the study and were categorized into five groups and 10 samples in each group as Group I-oral leukoplakia (OL), Group II-oral lichen planus (OLP), Group III-oral submucous fibrosis (OSMF), Group IV-oral squamous cell carcinoma (OSCC) and Group V-normal oral mucosa (NOM) as control group. All the samples were assessed for the expression of E-cad by immunohistochemical study.

Results:

Upon assessing the expression of E-cad in OL, OSMF, OLP and OSCC, as majority of the samples with OSCC (90%), OL (80%), OLP (70%) and OSMF (60%) showed mild to moderate expression of E-cad staining, which was suggestive of reduction in dysplastic cells on comparison to NOM cells. This difference in expression and variation of E-cad upon comparison with normal mucosa was statistically significant (P < 0.001).

Conclusion:

There is significant (P < 0.001) variation of expression of E-cad with the histopathological dysplasia of the oral precancerous lesions and conditions, and the tumor differentiation of the oral cancers. However, there was no correlation of the degree of loss of expression of E-cad with the degree of dysplasia or the tumor differentiation of oral cancers. We conclude with our study that, there is a variation in the expression of E-cad but its value as a prognostic marker is questionable.

150th Anniversary Series: Desmosomes and the Hallmarks of Cancer

Desmosomes represent adhesive, spot-like intercellular junctions that in association with intermediate filaments mechanically link neighboring cells and stabilize tissue architecture. In addition to this structural function, desmosomes also act as signaling platforms involved in the regulation of cell proliferation, differentiation, migration, morphogenesis, and apoptosis. Thus, deregulation of desmosomal proteins has to be considered to contribute to tumorigenesis. Proteolytic fragmentation and downregulation of desmosomal cadherins and plaque proteins by transcriptional or epigenetic mechanisms were observed in different cancer entities suggesting a tumor-suppressive role. However, discrepant data in the literature indicate that context-dependent differences based on alternative intracellular, signal transduction lead to altered outcome. Here, modulation of Wnt/β-catenin signaling by plakoglobin or desmoplakin and of epidermal growth factor receptor signaling appears to be of special relevance. This review summarizes current evidence on how desmosomal proteins participate in carcinogenesis, and depicts the molecular mechanisms involved.

Clinico-pathological correlation of E-cadherin expression at the invasive tumor front of Indian oral squamous cell carcinomas: An immunohistochemical study

Background:

Recent studies have indicated that although malignant cells at the invasive tumor front, bare morphological resemblance to the cells at central portion of the tumor, their molecular character differs significantly. E-cadherin is a cell-cell adhesion molecule that connects epithelial cells. This study attempts to correlate the E-cadherin expression at the invasive tumor front with tumor differentiation along with its clinico-pathological parameters.

Materials and Methods:

Immunohistochemical staining with E-cadherin was carried out on archival cases of primary oral squamous cell carcinomas (n = 30). The E-cadherin expression at the invasive tumor front was analyzed and was linked to clinico-pathological parameters including patient prognosis.

Results:

The downregulation of E-cadherin expression at the invasive tumor edge when compared with patient's prognosis yielded a significant correlation (P = 0.041) but its correlation with the degree of differentiation determined was not significant (P = 0.27). Also, its association with tumor size and lymph node status was negative.

Conclusions:

Loss of E-cadherin expression at the invasive tumor front is an important event in the progression of oral squamous cell carcinomas. Tumors with a loss of expression of E-cadherin are those which had a poor prognosis

Aberrant expression and altered cellular localization of desmosomal and hemidesmosomal proteins are associated with aggressive clinicopathological features of oral squamous cell carcinoma

Disruption of cell adhesion plays a central role in dedifferentiation, invasion, and metastasis of various cancers. The desmosome and hemidesmosome are anchoring junctions that control cell-cell and cell-matrix adhesion, respectively. To clarify their contributions in mediating the biological properties of oral cancer, we immunohistochemically examined the expression of desmoglein 1 (DSG1), DSG2, DSG3, desmocollin 2 (DSC2), integrin beta 4 (ITGB4), laminin gamma chain 2 (LAMC2), and collagen type 17 alpha 1 (COL17A1) in 51 cases of oral squamous cell carcinoma. On normal oral epithelial cells, DSG1, DSG3, DSC2, and COL17A1 were expressed on the plasma membrane, while ITGB4 and mature LAMC2 were present at the basement membrane. In cancer, the expression of DSG1, DSG3, DSC2, and COL17A1 decreased and internalized to the cytoplasm. Cytoplasmic expression of DSG2, ITGB4, and LAMC2 was induced in the cancer cells facing to the stroma. We scored immunohistochemical expression and correlated this to clinicopathological parameters including histologic differentiation, pattern of invasion, and presence of lymph node metastasis. Decrease of DSG3 and DSC2 expression correlated with a more aggressive cancer phenotype: less differentiated and more invasive histologic features and a higher incidence of nodal metastasis. Lower COL17A1 and higher LAMC2 expression were also associated with a more aggressive phenotype. The present study demonstrates that aberrant expression and altered cellular localization of desmosomal and hemidesmosomal proteins are associated with aggressive clinicopathological features of oral cancer. This reinforces the notion that disturbance of the keratin-associated anchoring junctions confers aggressive features to cancer cells.

Restoration of E-cadherin expression by selective Cox-2 inhibition and the clinical relevance of the epithelial-to-mesenchymal transition in head and neck squamous cell carcinoma

BACKGROUND

The epithelial-to-mesenchymal transition (EMT) accompanied by the downregulation of E-cadherin has been thought to promote metastasis. Cyclooxygenase-2 (Cox-2) is presumed to contribute to cancer progression through its multifaceted function, and recently its inverse relationship with E-cadherin was suggested. The aim of the present study was to investigate whether selective Cox-2 inhibitors restore the expression of E-cadherin in head and neck squamous cell carcinoma (HNSCC) cells, and to examine the possible correlations of the expression levels of EMT-related molecules with clinicopathological factors in HNSCC.

METHODS

We used quantitative real-time PCR to examine the effects of three selective Cox-2 inhibitors, i.e., celecoxib, NS-398, and SC-791 on the gene expressions of E-cadherin (CDH-1) and its transcriptional repressors (SIP1, Snail, Twist) in the human HNSCC cell lines HSC-2 and HSC-4. To evaluate the changes in E-cadherin expression on the cell surface, we used a flowcytometer and immunofluorescent staining in addition to Western blotting. We evaluated and statistically analyzed the clinicopathological factors and mRNA expressions of Cox-2, CDH-1 and its repressors in surgical specimens of 40 patients with tongue squamous cell carcinoma (TSCC).

RESULTS

The selective Cox-2 inhibitors upregulated the E-cadherin expression on the cell surface of the HNSCC cells through the downregulation of its transcriptional repressors. The extent of this effect depended on the baseline expression levels of both E-cadherin and Cox-2 in each cell line. A univariate analysis showed that higher Cox-2 mRNA expression (p = 0.037), lower CDH-1 mRNA expression (p = 0.020), and advanced T-classification (p = 0.036) were significantly correlated with lymph node metastasis in TSCC. A multivariate logistic regression revealed that lower CDH-1 mRNA expression was the independent risk factor affecting lymph node metastasis (p = 0.041).

CONCLUSIONS

These findings suggest that the appropriately selective administration of certain Cox-2 inhibitors may have an anti-metastatic effect through suppression of the EMT by restoring E-cadherin expression. In addition, the downregulation of CDH-1 resulting from the EMT may be closely involved in lymph node metastasis in TSCC.

Effects of epidermal growth factor on the invasive activity and cytoskeleton of oral squamous cell carcinoma cell lines

Epidermal growth factor (EGF) is present at high concentrations in human saliva and modulates the growth and differentiation of various cancer cells. To elucidate the molecular mechanisms by which EGF affects oral cancer proliferation and invasion, the current study analyzed the Matrigel invasion activity of cultured oral cancer cell lines. Cell proliferation under the influence of EGF was subjected to Matrigel invasion assays, and cell proliferation in the absence of EGF was used as control. Northern blot analyses quantified the invasiveness and tumorigenicity. Chloramphenicol acetyltransferase assay determined the EGF stimulation of matrix metalloproteinase (MMP) 1 expression. EGF increased the number of cells penetrating the Matrigel membrane. Northern blot analysis revealed that MMP1 and cytokeratin 19 expression correlate with EGF. In addition, the morphology of HSC-3 and SAS cells changed following the addition of EGF to the culture medium. A transient transfection assay revealed that EGF increases the promoter activities of MMP1 in HSC-3 cells. These observations suggested that EGF increases the invasive activity of oral cancer cells, partly by increasing MMP1, and morphological changes may be induced by altering the composition of cytoskeletal proteins.

Desmoglein 3 promotes cancer cell migration and invasion by regulating activator protein 1 and protein kinase C-dependent-Ezrin activation

Desmoglein 3 (Dsg3), the pemphigus vulgaris antigen, has recently been shown to be upregulated in squamous cell carcinoma (SCC) and has been identified as a good tumor-specific marker for clinical staging of cervical sentinel lymph nodes in head and neck SCC. However, little is known about its biological function in cancer. The actin-binding protein Ezrin and the activator protein 1 (AP-1) transcription factor are implicated in cancer progression and metastasis. Here, we report that Dsg3 regulates the activity of c-Jun/AP-1 as well as protein kinase C (PKC)-mediated phosphorylation of Ezrin-Thr567, which contributes to the accelerated motility of cancer cells. Ectopic expression of Dsg3 in cancer cell lines caused enhanced phosphorylation at Ezrin-Thr567 with concomitant augmented membrane protrusions, cell spreading and invasive phenotype. We showed that Dsg3 formed a complex with Ezrin at the plasma membrane that was required for its proper function of interacting with F-actin and CD44 as Dsg3 knockdown impaired these associations. The increased Ezrin phosphorylation in Dsg3-overexpressing cells could be abrogated substantially by various pharmacological inhibitors for Ser/Thr kinases, including PKC and Rho kinase that are known to activate Ezrin. Furthermore, a marked increase in c-Jun S63 phosphorylation, among others, was found in Dsg3-overexpressing cells and the activation of c-Jun/AP-1 was further supported by a luciferase reporter assay. Taken together, our study identifies a novel Dsg3-mediated c-Jun/AP-1 regulatory mechanism and PKC-dependent Ezrin phosphorylation that could be responsible for Dsg3-associated cancer metastasis.

Desmoglein-3/γ-catenin and E-cadherin/ß-catenin differential expression in oral leukoplakia and squamous cell carcinoma

OBJECTIVE

The purpose of this study was to investigate gene/protein expression alterations of intercellular connections' components in oral leukoplakia (OLs) and squamous-cell carcinoma (OSCCs).

MATERIALS AND METHODS

Expression of desmogleins-2,3 (Dsg2/Dsg3), E-cadherin, and their cytoplasmic ligand, β/γ-catenins were quantitatively assessed in HSC-3 cells growing as monolayer cultures (ML)/multicellular aggregates (MCAs), using RT-PCR/Western blot, whereas their localization was detected by immunofluorescence. Furthermore, their expression was semi-quantitatively investigated in tissues from 25 OLs/25 OSCCs, using automated immunohistochemistry.

RESULTS

The steady-state levels of Dsg3 RNA transcripts increased as HSC-3 cells enter their exponential phase of growth, before a dramatic decrease to be observed as cells reached their plateau phase especially in MCAs. Upon the same period of time, Dsg2 levels have been increased. The expression of γ-catenin but not that of β-catenin was increased after 48 h in both MLs and MCAs. In clinical samples, Dsg3, Ε-cadherin, β/γ-catenin down-regulation was observed to be associated with the grade of OLs-dysplasia and OSCCs. Importantly, a membrane-to-cytoplasmic switch of expression and strong perinuclear aggregation of Dsg3/γ-catenin was seen in both HSC-3 cells and OLs/OSCCs.

CONCLUSIONS

The altered expression of Dsg3/γ-catenin and E-cadherin/β-catenin, in vitro and in ODs/OSCC imply their involvement in growth regulation and phenotype of dysplastic/malignant oral epithelial cells, contributing to the better understanding of epithelial dysplasia and OSCCs.

CLINICAL RELEVANCE

The observed alterations of their expression suggest a role of Dsg3 and γ-catenin (additionally to E-cadherin/β-catenin) as biomarkers of malignant transformation risk of oral dysplasia and the biological behavior (aggressiveness) of oral cancer, respectively.

Loss of keratin 13 in oral carcinoma in situ: a comparative study of protein and gene expression levels using paraffin sections

Immunohistochemical loss of keratin (K)13 is one of the most valuable diagnostic criteria for discriminating carcinoma in situ (CIS) from non-malignancies in the oral mucosa while K13 is stably immunolocalized in the prickle cells of normal oral epithelium. To elucidate the molecular mechanism for the loss of K13, we compared the immunohistochemical profiles for K13 and K16 which is not expressed in normal epithelia, but instead enhanced in CIS, with their mRNA levels by in-situ hybridization in formalin-fixed paraffin sections prepared from 23 CIS cases of the tongue, which were surgically removed. Reverse transcriptase-PCR was also performed using RNA samples extracted from laser-microdissected epithelial fragments of the serial paraffin sections in seven of the cases. Although more enhanced expression levels for K16 were confirmed at both the protein and gene levels in CIS in these seven cases, the loss of K13 was associated with repressed mRNA levels in four cases, but not in the other three cases. The results suggest that the loss of K13 is partly due to its gene repression, but may also be due to some unknown post-translational events.

Expression of DSG1 and DSC1 are prognostic markers in anal carcinoma patients

Background:

Our purpose was to investigate if dysregulation of cell adhesion molecules could be linked to prognosis in squamous cell carcinomas (SCCs) of the anal region.

Methods:

Protein expression of desmoglein-1 (DSG1), desmocollin-1 (DSC1) and E-cadherin was studied by immunohistochemistry in a cohort of 53 anal carcinoma patients treated by radiation alone or combined with 5-fluorouracil and mitomycin C.

Results:

Univariate analyses identified, among others, negative membranous DSG1 staining (P=0.009), negative cytoplasmic DSC1 staining (P=0.012) and negative DSG1 (membranous)+negative DSC1 (cytoplasmic) staining (P=0.004) to be associated with improved cancer-specific survival (CSS). On multivariate analyses positive DSG1 (membranous)+DSC1 (cytoplasmic) staining (HR 6.95, P=0.044), large tumour size and lymph node metastases (HR 6.44, P=0.004) and radiation without chemotherapy (HR 6.73 P=0.004) were associated with worse CSS. On univariate analysis, improved disease-free survival was associated with negative membranous staining of DSG1 (P=0.047), and negative DSG1 (membranous)+negative DSC1 (cytoplasmic) staining (P=0.025), among others.

Conclusion:

Membrane negativity for DSG1 and cytoplasmic negativity for DSC1 are favourable markers for CSS in SCCs of the anal region.

Desmocollin 2 is a new immunohistochemical marker indicative of squamous differentiation in urothelial carcinoma

AIMS

Urothelial carcinoma (UC) with squamous differentiation tends to present at higher stages than pure UC. To distinguish UC with squamous differentiation from pure UC, a sensitive and specific marker is needed. Desmocollin 2 (DSC2) is a protein localized in desmosomal junctions of stratified epithelium, but little is known about its biological significance in bladder cancer. We examined the utility of DSC2 as a diagnostic marker.

METHODS AND RESULTS

We analysed the immunohistochemical characteristics of DSC2, and studied the relationship of DSC2 expression with the expression of the known markers uroplakin III (UPIII), cytokeratin (CK)7, CK20, epidermal growth factor receptor (EGFR), and p53. DSC2 staining was detected in 24 of 25 (96%) cases of UC with squamous differentiation, but in none of 85 (0%) cases of pure UC. DSC2 staining was detected only in areas of squamous differentiation. DSC2 expression was mutually exclusive of UPIII expression, and was correlated with EGFR expression. Furthermore, DSC2 expression was correlated with higher stage (P = 0.0314) and poor prognosis (P = 0.0477).

CONCLUSIONS

DSC2 staining offers high sensitivity (96%) and high specificity (100%) for the detection of squamous differentiation in UC. DSC2 is a useful immunohistochemical marker for separation of UC with squamous differentiation from pure UC.

Expression of cathepsin D and E-cadherin in primary laryngeal cancers correlation with neck lymph node involvement

OBJECTIVE

The aim of this study was to investigate the relation between Cathepsin D (Cath-D) and E-Cadherin (E-Cad) expression levels in tumor tissue and neck lymph node metastasis. This attempt should be made to identify new factors that one could be useful in predicting clinical behavior.

STUDY DESIGN

In this study, we investigated rates of dying for E-Cad and Cath-D in paraphin blocks of larynx and neck dissection specimens taken from 56 selected patients. Laryngeal specimens dyed by ECad and Cath-D immunohistochemically. Immunoreactivity classified for E-Cad as positive (75% and above), reduced (25-75%) and negative (below 25%). Immunoreactivity classified for Cath-D:dye absorption rates higher than 50% evaluated positive and absorption rates lower than 50% evaluated negative. We compared the rates of dying for E-Cad and Cath-D groups to with or without neck lymph node metastasis in specimens.

RESULTS

Neck metastasis were found in 41% of patients, in 55.6% of patients, if the E-Cad was negative, 40.6% if it was reduced, 33.3% if it was positive in specimens. The neck metastasis was found in 35.4% of patients with Cath-D expression negative, while 75% of patients was found with Cath-D expression positive.

CONCLUSION

Neck metastasis was found higher in E-Cad reduced group than positive group. Neck node metastasis was significantly higher in Cath-D positive group than Cath-D negative group. Cath-D and E-Cad essays may useful in identifying neck lymph node involvement. Cath-D expression levels are more in this predictive factor than E-Cad levels for possibility of neck lymph node metastasis in LSCC.

Effects of E-cadherin (CDH1) gene promoter polymorphisms on the risk and clinicopathologic development of oral cancer

BACKGROUND

This study investigates the association between polymorphism in the E-cadherin/CDH1 promoter region and the risk and progression of oral cancer.

METHODS

Genetic polymorphisms of CDH1-160 and -347 were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 347 noncancer controls and in 251 patients with oral cancer.

RESULTS

The statistical analysis showed that subjects with at least 1 varied GA allele of CDH1-347 polymorphic genotypes or combinations of the CDH1-160 CA/-347 GGA, CDH1-160 CC/-347 GGA, or CDH1-160 CC/-347 GAGA genotypes had a significantly higher risk, whereas subjects with CDH1-160 C/A or A/A had a significantly lower risk of developing oral cancer than those with wild-type genotypes. Furthermore, elderly patients with the CDH1-347 G/GA or GA/GA genotype were associated with a higher incidence in lymph node metastasis than were those with the G/G genotype.

CONCLUSIONS

These results suggest that CDH1-347 polymorphisms are associated with increased risks of oral cancer, and may be a predictive factor for tumor lymph node metastasis.

Desmoglein 3, via an interaction with E-cadherin, is associated with activation of Src

Background

Desmoglein 3 (Dsg3), a desmosomal adhesion protein, is expressed in basal and immediate suprabasal layers of skin and across the entire stratified squamous epithelium of oral mucosa. However, increasing evidence suggests that the role of Dsg3 may involve more than just cell-cell adhesion.

Methodology/Principal Findings

To determine possible additional roles of Dsg3 during epithelial cell adhesion we used overexpression of full-length human Dsg3 cDNA, and RNAi-mediated knockdown of this molecule in various epithelial cell types. Overexpression of Dsg3 resulted in a reduced level of E-cadherin but a colocalisation with the E-cadherin-catenin complex of the adherens junctions. Concomitantly these transfected cells exhibited marked migratory capacity and the formation of filopodial protrusions. These latter events are consistent with Src activation and, indeed, Src-specific inhibition reversed these phenotypes. Moreover Dsg3 knockdown, which also reversed the decreased level of E-cadherin, partially blocked Src phosphorylation.

Conclusions/Significance

Our data are consistent with the possibility that Dsg3, as an up-stream regulator of Src activity, helps regulate adherens junction formation.

A molecular study of desmosomes identifies a desmoglein isoform switch in head and neck squamous cell carcinoma

Desmosomes, the intercellular junctions that confer strong adhesion between epithelial cells, are frequently altered in malignancy. However, a comprehensive analysis of these structures has not been carried out in oral neoplasia. Oral squamous cell carcinomas (SCCs) and pre-malignant dysplasia can be sub-classified according to their in vitro replicative lifespan, where the immortal dysplasia (ID) and carcinoma (IC) subsets have p16(ink4a) and p53 dysfunction, telomerase deregulation and genetic instability and the mortal subset (MD and MC) do not. We found that the desmosomal proteins exhibit a distinct expression pattern in oral mucosa when compared with epidermis in vivo. Microarray data from a large panel of lines revealed that the transcript levels of DSG3, DSC2/3, DP, PG and PKP1 were reduced in ID and IC. Interestingly, DSG2 was up-regulated in MC. Reduction of DSG3 and up-regulation of DSG2 were found in two independent microarray datasets. Significantly, we demonstrated that reduction of DSG3 and up-regulation of DSG2 was reversible in vitro by using RNAi-mediated knockdown of DSG2 in IC cells. The remaining desmosomal proteins were largely disrupted or internalized and associated with retraction of keratin intermediate filaments in oral SCC lines. These findings suggest dysfunction and loss of desmosomal components are common events in the immortal class of oral SCC and that these events may precede overt malignancy.

Genetic deletion of the desmosomal component desmoplakin promotes tumor microinvasion in a mouse model of pancreatic neuroendocrine carcinogenesis

We used the RIP1-Tag2 (RT2) mouse model of islet cell carcinogenesis to profile the transcriptome of pancreatic neuroendocrine tumors (PNET) that were either non-invasive or highly invasive, seeking to identify pro- and anti-invasive molecules. Expression of multiple components of desmosomes, structures that help maintain cellular adhesion, was significantly reduced in invasive carcinomas. Genetic deletion of one of these desmosomal components, desmoplakin, resulted in increased local tumor invasion without affecting tumor growth parameters in RT2 PNETs. Expression of cadherin 1, a component of the adherens junction adhesion complex, was maintained in these tumors despite the genetic deletion of desmoplakin. Our results demonstrate that loss of desmoplakin expression and resultant disruption of desmosomal adhesion can promote increased local tumor invasion independent of adherens junction status.

The ability of a tumor to invade into the surrounding normal tissue is one hallmark of a malignant cancer. We sought to identify factors that either restrict or promote tumor invasion in a genetically engineered mouse model of pancreatic neuroendocrine cancer by characterizing the transcriptional profiles of the non-invasive and invasive pancreatic neuroendocrine tumors (PNET) that develop in this model. This analysis demonstrated that multiple genes encoding components of desmosomes, cellular structures dedicated to the maintenance of cell-cell adhesion, were expressed at much lower levels in invasive PNETs, suggesting that loss of desmosomal adhesion contributes to the development of an invasive phenotype in these tumors. Genetic deletion of one of these desmosomal components in PNET-bearing mice resulted in increased local tumor invasion. These results are important since the development of an invasive phenotype is associated with a poor prognosis for many human cancers and is often a precursor to the development of distant metastases. Our findings demonstrate one mechanism by which tumors can acquire such an invasive phenotype and may prove useful in evaluating the malignancy of human cancers.

Cyclin D1 overexpression increases susceptibility to 4-nitroquinoline-1-oxide-induced dysplasia and neoplasia in murine squamous oral epithelium

The cyclin D1 oncogene is frequently amplified/overexpressed in oral squamous cell carcinomas. Mice with overexpression of cyclin D1 targeted to the stratified squamous epithelia of the tongue, esophagus, and forestomach develop a phenotype of epithelial dysplasia at these sites. In this study, we examined the effect of cyclin D1 overexpression on susceptibility of mice to carcinogen-induced tumorigenesis, using 4-nitroquinoline-1-oxide (4NQO), an established potent oral carcinogen in mice. Cyclin D1 overexpressing mice and nontransgenic littermates were administered 4NQO (20 or 50 parts per million (ppm) in the drinking water) for 8 wk and monitored for an additional 16 wk. Histopathological analyses of the tongue revealed significantly higher severity of dysplasia in the cyclin D1 overexpression mice, compared with nontransgenic controls and with untreated controls. Moreover, only the cyclin D1 overexpression mice developed neoplastic lesions in the oro-esophageal epithelia. Examination of the dysplastic and neoplastic lesions revealed abnormal proliferation. Our findings suggest that cyclin D1 overexpression enhances susceptibility to carcinogen-induced oral tumorigenesis. These results underscore the importance of cyclin D1 in the process of oral neoplastic development. Further, they emphasize the value of this transgenic model to study the pathogenesis of oral precancer and cancer and establish it as a model system to test candidate agents for chemoprevention of upper aero-digestive cancer.

Increased expression of Dsg2 in malignant skin carcinomas: A tissue-microarray based study

Desmoglein 2 (Dsg2), a transmembrane cadherin of the desmosomal cell-cell adhesion structure, is downregulated with epithelial differentiation. We recently demonstrated that overexpression of Dsg2 in epidermal keratinocytes deregulates multiple signaling pathways associated with increased growth rate, anchorage-independent cell survival, and the development of skin tumors. While changes in Dsg2 expression have been observed in neoplastic lesions, the correlation of expression levels and localization of Dsg2 and the state of tumor development has not been fully established. Here we generated a highly sensitive Dsg2 antibody (Ab10) and characterized that antibody along with a previously developed Dsg2 specific antibody 10D2. Using these antibodies in immunostaining of tissue microarrays, we show a dramatic upregulation of Dsg2 expression in certain human epithelial malignancies including basal cell carcinomas (BCC; n = 12), squamous cell carcinomas (SCC; n = 57), carcinomas of sebaceous and sweat glands (n = 12), and adenocarcinomas (n = 3). Dsg2 expression was completely absent in malignant fibrosarcomas (n = 16) and melanomas (n = 15). While Dsg2 expression was consistently strong in BCC, it varied in SCC with a minor correlation between a decrease of Dsg2 expression and tumor differentiation. In summary, we have identified Dsg2 as a potential novel marker for epithelial-derived malignancies.

Src family kinases mediate betel quid-induced oral cancer cell motility and could be a biomarker for early invasion in oral squamous cell carcinoma

Betel quid (BQ)-chewing oral cancer is a prevalent disease in many countries of Southeast Asia. Yet, the precise disease mechanism remains largely unknown. Here, we show that BQ extract-induced cell motility in three oral cancer cells (Ca9-22, SAS, and SCC9) presumably involves the Src family kinases (SFKs). Besides, BQ extract can markedly induce cell migration of wild type mouse embryonic fibroblasts (MEFs) but not MEFs lacking three SFK members, namely, Src, Yes, and Fyn, indicating the requirement of SFKs for BQ-induced cell motility. Betel quid extract can also elevate cellular SFK activities because phosphorylation of tyrosine 416 at the catalytic domain is increased, which in turn promotes phosphorylation of an in vitro substrate, enolase. Furthermore, we identified that areca nut, a major component of BQ, is the key factor accounting for BQ-induced cell migration and invasion through SFKs-mediated signaling pathways. Immunohistochemistry revealed that, particularly in BQ-chewing cases, the activity of SFKs was significantly higher in tumor-adjacent mucosa than that in solid tumor areas (P < .01). These results suggest a possible role of SFKs in tumor-host interface and thus in early tumor invasion in vivo. Consistent with this is the observation that activation of SFKs is colocalized with invasive tumor fronts in oral squamous cell carcinoma. Together, we conclude that SFKs may represent a potential biomarker of invasion and therapeutic target in BQ-induced oral cancer.

Desmocollin expression in oral atrophic lichen planus correlates with clinical behavior and DNA content

BACKGROUND

Oral lichen planus (OLP) is a chronic mucocutaneous inflammatory disease, with some tendency toward malignant transformation. Markers are needed to identify the lesions at risk.

METHODS

A series of 82 biopsies from 70 patients with atrophic OLP was analyzed for desmocollin-1, E-cadherin, cyclin-dependent kinase 1 (cdk-1) and Rad-51 expression using immunohistochemistry and static DNA cytometry, with particular reference to clinical outcome.

RESULTS

Desmocollin-1 and E-cadherin expression were each detected in 24.4% (20/82) of the samples. Of the positive samples, only eight specimens expressed both desmocollin-1 and E-cadherin. Strong desmocollin-1 and E-cadherin expression was found in 8.5% and 3.7% of OLP biopsies, respectively. Desmocollin-1 expression increased the risk of dysplasia 31.8-fold (95% confidence intervals (CI) 3.6-280.9; p = 0.0001), while E-cadherin was significantly related to cancer (odds ratio (OR) = 5.13; 95% CI 3.3-8.1; p = 0.001). In univariate survival analysis, desmocollin-1 was a significant predictor of both cancer (log-rank test; p = 0.033) and dysplasia (p = 0.0001), while E-cadherin predicted the development of cancer (p = 0.0001). Neither cdk-1 nor Rad-51 had any predictive value. Importantly, desmocollin-1 retained its value as the only independent predictor of dysplasia in the multivariate (Cox) model (adjusted Hazard Ratio (HR) = 44.13; 95% CI 3.7-525.6).

CONCLUSIONS

In atrophic OLP, desmocollin-1 is a powerful predictor of an important intermediate endpoint marker (dysplasia) in the causal pathway toward oral cancer.

Structure and function of desmosomes

Desmosomes are prominent adhesion sites that are tightly associated with the cytoplasmic intermediate filament cytoskeleton providing mechanical stability in epithelia and also in several nonepithelial tissues such as cardiac muscle and meninges. They are unique in terms of ultrastructural appearance and molecular composition with cell type-specific variations. The dynamic assembly properties of desmosomes are important prerequisites for the acquisition and maintenance of tissue homeostasis. Disturbance of this equilibrium therefore not only compromises mechanical resilience but also affects many other tissue functions as becomes evident in various experimental scenarios and multiple diseases.

Altered expression of desmocollin 3, desmoglein 3, and beta-catenin in oral squamous cell carcinoma: correlation with lymph node metastasis and cell proliferation

Desmocollin 3 (Dsc3) and desmoglein 3 (Dsg3) are both transmembrane glycoproteins that belong to the cadherin family of calcium-dependent cell adhesion molecules. beta-Catenin is a member of the cadherin-catenin complex that mediates homotypic cell-cell adhesion and is also an important molecule in the wnt signaling pathway. In this study, we examined the simultaneous expression level of Dsc3, Dsg3, and beta-catenin in oral squamous cell carcinomas (OSCCs) and normal oral epithelia using immunohistochemistry. There was a significant correlation (p < 0.05) among the following variables in OSCCs: reduced or loss of expression of Dsc3, Dsg3, and beta-catenin compared to normal oral epithelium, reduced or loss of expression of Dsc3 and histological grade (moderately or poorly differentiated), and reduced or loss of expression of beta-catenin and lymph node metastasis. Furthermore, a positive correlation was found between reduced or loss of beta-catenin staining and reduced or loss of Dsc3 staining in lymph node metastatic cancer tissue (r = 0.734, p < 0.05). These results suggest an abnormal expression of Dsc3, Dsg3, and beta-catenin induced in the progression of oral carcinomas and that the Dsc3 expression level might be related to the regulation of beta-catenin in lymph node metastasis and cell proliferation in OSCCs.

Expression of E-cadherin in cervical lymph nodes from primary oral squamous cell carcinoma patients

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor in oral and maxillofacial region with poor prognosis. E-cadherin plays a key role in cell-to-cell adhesion. E-cadherin expression in the metastatic cervical lymph node, especially in the micrometastatic cervical lymph node has seldom been reported in OSCC patients.

OBJECTIVE

To investigate the E-cadherin expression in cervical lymph nodes from OSCC patients as well as its clinical significance.

DESIGN

Thirty-three OSCC patients were involved in this study; among them, there were 28 males and 5 females, the age ranged from 34 to 78 years (mean 58.8 years). The most suspicious metastatic cervical lymph node (total 99 lymph nodes) from three cervical regions of each OSCC patient was selected for detection of E-cadherin using routine pathological examination and immunohistochemistry.

RESULTS

Increased E-cadherin expression in the metastatic cervical lymph nodes was detected, which was diagnosed by routine pathological examination using HE staining. However, in the micrometastatic cervical lymph node, E-cadherin expression was negative. The survival rate of OSCC patients correlated with decreased E-cadherin expression (P=0.001), N stage (P=0.024) and tumor recurrence (P<0.001). Tumor recurrence is the only independent factor on the prognosis (RR=20.83 and P=0.014).

CONCLUSIONS

Decreased E-cadherin expression in cancerous tissue correlates with the poor prognosis of OSCC patients. Detection of E-cadherin expression is useful to confirm the cervical lymph node metastasis and maybe useless to detect the cervical lymph node micrometastasis; further studies are encouraged to reveal the detail mechanism of E-cadherin expression in formation of lymph node metastatic focus.

Signal transduction pathways involved in epithelial-mesenchymal transition in oral cancer compared with other cancers

Epithelial-mesenchymal transition (EMT) is a central mechanism governing destined cell movement in embryonic development. Emerging evidence reveals that EMT characterizing the progression of many carcinomas is linked to the acquisition of an invasive and metastatic phenotype. While it is established that EMT is controlled by well-conserved mechanisms, additional research is required for various tissue- or tumor-specific transitions. We review the literature related to the major components of EMT including adhesion molecules, cytoskeleton reorganization and signaling pathways in oral cancer.

Altered E-cadherin/?-catenin expression in oral squamous carcinoma with and without nodal metastasis

OBJECTIVES

The aim of this study was to investigate the potential use of E-cadherin, a tumour-suppressor gene product involved in establishing cell-cell adhesion and one of its associated proteins, beta-catenin, as markers of nodal metastasis in oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Thirty invasive OSCCs in patients with (n = 19) and without (n = 11) nodal metastases, as confirmed on histopathologic examination of the resected regional lymph nodes (n = 30), were examined for E-cadherin and beta-catenin expression by immunohistochemistry.

RESULTS

There was a highly significant association (P < 0.0001) between E-cadherin and beta-catenin expression and tumour differentiation by conventional Broders' grading of the whole tumour. Irrespective of the nodal status and invasive tumour front (ITF) grading score, however, loss of expression was recorded at the ITF in 28 (93%) of 30 tumours and 22 (73%) of 30 tumours stained for E-cadherin and beta-catenin respectively.

CONCLUSION

The results of this study suggest an association between loss of expression of E-cadherin and beta-catenin and a lower degree of differentiation; however, their use as markers of nodal metastasis in OSCC appears unreliable.

Expression of E-cadherin, P-cadherin and N-cadherin in oral squamous cell carcinoma: correlation with the clinicopathologic features and patient outcome

PURPOSE

Alteration of cadherin expression is associated with the loss of cellular differentiation, the acquisition of an invasive phenotype and a poor prognosis in many types of cancer. This study aimed to evaluate the immunoreactivity of E-, P- and N-cadherins (cad) in oral squamous cell carcinoma and to correlate their expression with clinicopathological features and clinical outcome. The interaction between the cadherins was also investigated.

METHODS

A total of 71 tissue samples were examined by immunohistochemical methods on paraffin sections using specific antibodies.

RESULTS

In the primary lesions and lymph node metastases, the immunoreactivity of E-cad was reduced and P-cad was over-expressed, but the expression of N-cad was negative (p<0.001, 0.01 and 0.05, respectively). The reduced primary E-cad expression was related to the invasion pattern and lymph node metastasis (p=0.046 and 0.037, respectively). However, the expression of cadherins did not appear to differ significantly in relation to the histological grade, invasion, tumour size, stage of oral SCC or tumour recurrence. A much greater reduction in the expression of E-cad was found in the positive N-cadherin group (p=0.008). Nonetheless, cadherin expression was not significantly associated with failure-free survival or overall survival in this experiment subset.

CONCLUSION

The reduced E-cad expression and the aberrant N-cad expression are closely associated with each other in oral cancer cases, and this suggests that cadherin switching from E. cad to N. cad may play a critical role in cancer development and metastasis.

Metastatic lesion of the anterior mandible with an occult primary: a case report

Metastatic tumors to the oral cavity are relatively uncommon and account for about 1% of all oral cancers. Distant metastases to the jawbone are associated with a poor prognosis and a survival rate that is usually less than one year. The leading common primary sites for these lesions are the breast in females and the lung in males followed by the adrenals, kidneys, prostate, thyroid and colon. In 30% of all cancers, a metastatic lesion could be the first sign of a primary tumor elsewhere in the body. Metastatic lesions to the jaws are known to simulate periodontal and pulpal disease and other radiolucent lesions that can occur in the jaws. Microscopic evaluation with concurrent radiographic skeletal survey is warranted in patients where a metastatic lesion is suspected.

Molecular mediators of metastasis in head and neck squamous cell carcinoma

BACKGROUND

The presence of regional metastasis in patients with head and neck squamous cell carcinoma (HNSCC) is a common and adverse event associated with poor prognosis and high mortality. Although significant improvements in standard therapies have increased the efficacy of local tumor management, the high incidence of tumor recurrence has resulted in limited improvements in overall survival rates. Understanding the molecular mechanisms that mediate HNSCC invasion and metastasis may enable identification of novel therapeutic targets for the prevention and management of tumor dissemination.

METHODS

A literature review was performed.

RESULTS

Several biologic mediators and mechanisms that have been implicated in HNSCC metastasis, such as cell adhesion molecules, proteolytic enzymes, growth factor signaling, metastasis suppressor genes, and chemokine receptors were reviewed.

CONCLUSIONS

Prevention of HNSCC metastasis is an important clinical objective that requires an increased understanding of the molecular mechanisms of tumor invasion and dissemination.

Differential expression and distribution of epithelial adhesion molecules in non-small cell lung cancer and normal bronchus

BACKGROUND

Changes in epithelial cell interactions have been implicated in carcinogenesis, tumour invasion and metastasis.

AIM

To screen for altered expression of epithelial adhesion genes in lung cancer development.

METHODS

Gene expression profiles were assessed with cDNA expression arrays in eight non-small cell lung cancer (NSCLC) and eight normal bronchi obtained from the same patient. Immunohistochemistry (IHC) and RNA in situ hybridisation (ISH) were used to confirm the most prominently expressed adhesion molecules and to investigate their distribution at protein and mRNA levels.

RESULTS

43 differentially expressed cancer-related genes were identified in adenocarcinoma, squamous cell carcinoma (SCC) and normal bronchus. Five of these genes are related to epithelial adhesion-that is, integrin alpha3 (ITGA3), integrin beta4 (ITGB4), desmoplakin I and II (DSP), plakoglobin, and desmocollin 3 (DSC3). ITGA3 and ITGB4, showing predominantly cell-matrix staining, were up regulated in adenocarcinoma and SCC, respectively. ITGB4 also showed strong staining in SCC with IHC and ISH. Components of the desmosome adhesion complex DSP, plakoglobin and DSC3 were strongly up regulated in SCC and showed a distinct cell-cell staining pattern. DSP and plakoglobin were predominantly present at central, more differentiated tumour cells, whereas DSC3 showed a stronger staining in the peripheral basal cells of SCC tumour areas.

CONCLUSIONS

Lack of cellular adhesion may have an important role in the metastatic potency of a primary tumour. A possible association of strong presence and normal-distributed desmosomal molecules in SCC with the less frequent and late pattern of metastasis in SCC as compared with adenocarcinoma is suggested.

Reduced E-cadherin expression is an indicator of unfavourable prognosis in oral squamous cell carcinoma

The aim was to evaluate E-cadherin expression in oral squamous cell carcinoma, and its possible relationships with tumour histology and with clinical course and survival. Surgical biopsies from 47 cases of oral squamous cell carcinoma were analysed for expression of E-cadherin using immunohistochemistry. Statistical analyses were performed to identify possible associations with tumour clinic-histological features and with clinical course and survival. Weak or absent E-cadherin expression was associated with a more invasive histological pattern and with metastasis to the cervical lymph nodes. Uni- and multivariate analyses indicated that weak or undetectable E-cadherin expression is an indicator of shorter disease-free period and shorter survival time. Reduced E-cadherin expression in oral squamous cell carcinoma is associated with more aggressive tumour behaviour and worse prognosis.

Synthesis of junctional proteins in metastasizing colon cancer cells

Various authors have reported reduced synthesis of epithelial junctional proteins during dedifferentiation, tumorigenesis and metastasis in a great variety of tumors. Consequently, it is generally accepted that loss of adhesive molecules and adhesion structures is implicated in the development of an invasive phenotype and poor patient prognosis. Colon carcinomas, on the other hand, were shown to behave differently as synthesis of main adhesive proteins continues despite the development of an invasive phenotype. In this study we used cultured cells grown under conditions that inhibited intercellular adhesion (low Ca2+ concentration) and compared these results with data obtained from metastasizing colon cancer cells (signet ring cell carcinoma). Characterization of these proteins and their structures were performed by immunoprecipitations, Western blot analysis, immunohistochemistry, pre-embedding immuno-electron microscopy, and a new method to perform immuno-electron microscopy on paraffin-embedded material, which we present in this paper. We demonstrate that synthesis carries on for both, the desmosomal and the proteins of the zonula adhaerens. While, however, the assembly of desmosomal structures in the form of half-desmosomes at the cell surface continues, those of the zonula adhaerens did not. Instead E-cadherin was found, although associated with alpha-catenin, beta-catenin, and plakoglobin, evenly distributed at the plasma membrane of the cultured cells and also at the surface of the dissociated tumor cells. We conclude from our observations that continued expression and synthesis of junctional proteins do not necessarily contribute to the suppression of tumor invasion and metastasis of colon cancer.

E-cadherin is a selective and strongly dominant prognostic factor in squamous cell carcinoma: a comparison of E-cadherin with desmosomal components

E-cadherin-mediated and desmosomal cell-cell adhesion have been implicated in the suppression of invasive and metastatic behavior of squamous cell carcinomas. Whether the adhaerens junction represented by E-cadherin and the desmosomes interplay or have distinct and separate roles in squamous cell cancer progression is still unclear. We have studied a cohort of 200 primary tumors and 56 lymph node metastases from different anatomic sites of the head and neck region for changes in synthesis of E-cadherin, desmoplakin and desmoglein by immunohistochemistry (IHC). Selected cases were studied by indirect immunofluorescence (IIF) and electron microscopy (EM). Only frozen sections were evaluated since they gave stronger and reproducible staining results. IHC data obtained were compared to clinical parameters. While some reduction in immunostaining was found in virtually all invasive tumors, at least partial expression, including that of E-cadherin, persisted in most late stage tumors and in lymph node metastases. Reduced desmosomal staining correlated with desmosomes reduced in numbers, size or in structural defects by EM analysis. By univariate analysis, reduction in synthesis of both E-cadherin and the desmosomal components that were generally linked (i.e., they showed positive rank correlations) were significantly associated with clinical parameters including overall and disease-free survival. However, by multivariate analysis including a Cox proportional hazards regression model (backward selection), the desmosomal components were not significant as independent prognostic factors. By contrast, E-cadherin was strongly associated with patient prognosis. In line with the highly significant association of reduced E-cadherin synthesis with an increased relative risk of follow up events, i.e., regional lymph node (p = 0.0007) and distant metastasis (p < 0.0001), as well as local recurrences (p < 0.0001), the prognostic strength of E-cadherin was independent of and stronger than histological grading, N stage, tumor site, and even stronger than the TNM stage. Based on these results, evaluation of E-cadherin in squamous cell carcinomas by immunostaining is recommended as a significant prognostic marker.

Plakoglobin suppresses keratinocyte motility through both cell-cell adhesion-dependent and -independent mechanisms

Plakoglobin (PG) is a member of the Armadillo family of adhesion/signaling proteins and has been shown to play a critical role in the organization of desmosomes and tissue integrity. Because dissolution of intercellular junctions is frequently an initial step in the onset of epithelial cell migration, we examined whether loss of PG promotes cell motility by compromising adhesive strength. Keratinocyte cultures established from PG-/-mice exhibited weakened adhesion and increased motility in transwell migration assays; both were restored by reintroducing PG through adenoviral infection. Interestingly, single PG-/- cells also exhibited increased motility, which was suppressed by reintroducing PG, but not the closely related beta-catenin. Whereas both N- and C-terminally truncated PG deletion mutants restored adhesion, only N-terminally deleted PG, but not C-terminally deleted PG, suppressed single-cell migration. Furthermore, both the chemical inhibitor PP2 and dominant-negative Src tyrosine kinase inhibited single-cell motility in PG-/- cells, whereas constitutively active Src overcame the inhibitory effect of PG. These data demonstrate that PG strengthens adhesion and suppresses motility in mouse keratinocytes, through both intercellular adhesion-dependent and -independent mechanisms, the latter of which may involve suppression of Src signaling through a mechanism requiring the PG C terminus.

Invasion and metastasis of oral cancer cells require methylation of E-cadherin and/or degradation of membranous beta-catenin

The extent of lymph node metastasis is a major determinant in the prognosis of oral squamous cell carcinoma (OSCC). Abnormalities of cell adhesion molecules are known to play an important role in invasion and metastasis of cancer cells through the loss of cell-to-cell adhesion. In this study, we isolated highly invasive clones from an OSCC cell line established from a lymph node metastasis by using an in vitro invasion assay method and compared the abnormalities of cell adhesion molecule E-cadherin and beta-catenin in these cells. The isolated, highly invasive clones showed significant invasive capacity and reduction of E-cadherin and membranous beta-catenin protein in comparison with parent cells. We found that reduced expression of E-cadherin was due to methylation of its promoter region. In fact, most invasive and metastatic area of OSCCs showed reduced expression and methylation of E-cadherin. Moreover, we found that reduced expression of membranous beta-catenin was due to its protein degradation. Reduced expression of membranous beta-catenin was also found frequently in invasive and metastatic areas of OSCCs. In summary, invasion and metastasis of OSCC cells require methylation of E-cadherin and/or degradation of membranous beta-catenin. In addition, we suggest that the method of isolation of highly invasive clones may be useful for studies aimed at discovering novel genes involved in invasion and metastasis.

Expression of desmosomal proteins in squamous cell carcinomas of the skin

BACKGROUND

Desmosomal proteins are well established markers of epithelial differentiation. Down-regulation of desmosomal proteins has been suggested to be a sign of reduced adhesiveness in metastasizing cells.

METHODS

We examined actinic keratoses, Bowen's disease, and squamous cell carcinoma (SCC) of the skin for the expression of desmosomal proteins using isoform-specific antibodies on paraffin-embedded sections. Evaluation was performed qualitatively in comparison to the epidermis and semiquantitatively using an area-intensity-score.

RESULTS

We found no qualitative correlation of desmoplakin or plakoglobin expression with risk of metastasis. Plakophilin 1, desmoglein 1, and the desmocollins 1-3 were found to be heterogeneously expressed in all neoplasms without significant correlation to aggressive tumor behavior. Plakophilin 2 was not expressed in any of the neoplasms examined. As most striking finding, desmoglein 2 was up-regulated qualitatively in half of all neoplasms examined and showed a significant higher proportion of positive cells in high-risk SCC than in low-risk SCC.

CONCLUSIONS

Desmosomal proteins are highly regulated in cutaneous SCC. Only desmoglein 2 expression correlates with risk of metastasis. Desmosomes may still be functional in metastasizing tumor cells.

Clinical, cellular, and molecular aspects of cancer invasion

Invasion causes cancer malignancy. We review recent data about cellular and molecular mechanisms of invasion, focusing on cross-talk between the invaders and the host. Cancer disturbs these cellular activities that maintain multicellular organisms, namely, growth, differentiation, apoptosis, and tissue integrity. Multiple alterations in the genome of cancer cells underlie tumor development. These genetic alterations occur in varying orders; many of them concomitantly influence invasion as well as the other cancer-related cellular activities. Examples discussed are genes encoding elements of the cadherin/catenin complex, the nonreceptor tyrosine kinase Src, the receptor tyrosine kinases c-Met and FGFR, the small GTPase Ras, and the dual phosphatase PTEN. In microorganisms, invasion genes belong to the class of virulence genes. There are numerous clinical and experimental observations showing that invasion results from the cross-talk between cancer cells and host cells, comprising myofibroblasts, endothelial cells, and leukocytes, all of which are themselves invasive. In bone metastases, host osteoclasts serve as targets for therapy. The molecular analysis of invasion-associated cellular activities, namely, homotypic and heterotypic cell-cell adhesion, cell-matrix interactions and ectopic survival, migration, and proteolysis, reveal branching signal transduction pathways with extensive networks between individual pathways. Cellular responses to invasion-stimulatory molecules such as scatter factor, chemokines, leptin, trefoil factors, and bile acids or inhibitory factors such as platelet activating factor and thrombin depend on activation of trimeric G proteins, phosphoinositide 3-kinase, and the Rac and Rho family of small GTPases. The role of proteolysis in invasion is not limited to breakdown of extracellular matrix but also causes cleavage of proinvasive fragments from cell surface glycoproteins.

Functional anatomy of the lymphatic drainage system of the upper aerodigestive tract and its role in metastasis of squamous cell carcinoma

BACKGROUND

Although there is a significant understanding of the vascular anatomy of the upper aerodigestive tract (UADT), there is less detailed knowledge of the architecture and drainage patterns of the lymphatic system. Detailed knowledge of the lymphatic system is critical for understanding the role of sentinal node identification in the management of different cancers.

METHODS

We have combined microscopic techniques with in vivo and in vitro lymphographic studies to survey the architecture and drainage patterns of the lymphatic system of the UADT in 850 organ specimens.

RESULTS

These studies show an interaction of superficial and deep lymphatic networks that vary in density but have a constant distribution characterized by predictable patterns of lymph drainage into the regional lymph nodes.

CONCLUSIONS

Detailed knowledge of the lymphatic system of the UADT contributes to a better understanding of the patterns of metastatic spread of carcinomas of the UADT and provides a strong rationale for the practice of sentinel node identification in the management of these tumors.

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.