Molecular profiling of tumour budding implicates TGFß-mediated epithelial-mesenchymal transition as a therapeutic target in oral squamous cell carcinoma.

Although tumour budding is an adverse prognostic factor for many cancer types, the molecular mechanisms governing this phenomenon are incompletely understood. Therefore, understanding the molecular basis of tumour budding may provide new therapeutic and diagnostic options. We employ digital image analysis to demonstrate that the number of tumour buds in cytokeratin-stained sections correlates with patients having lymph node metastases at diagnosis. The tumour bud count was also a predictor of overall survival, independent of TNM stage. Tumour buds and paired central tumour areas were subsequently collected from oral squamous cell carcinoma (OSCC) specimens, using laser capture microdissection, and examined with RNA sequencing and miRNA-qPCR arrays. Compared with cells from the central parts of the tumours, budding cells exhibited a particular gene expression signature, comprising factors involved in epithelial-mesenchymal transition (EMT) and activated TGFß signalling. Transcription factors ZEB1 and PRRX1 were up-regulated concomitantly with the decreased expression of mesenchymal-epithelial (MET) transcription factors (eg OVOL1) in addition to Krüppel-like factors and Grainyhead-like factors. Moreover, miR-200 family members were down-regulated in budding tumour cells. We used immunohistochemistry to validate five markers of the EMT/MET process in 199 OSCC tumours, as well as in situ hybridization in 20 OSCC samples. Given the strong relationship between tumour budding and the development of lymph node metastases and an adverse prognosis, therapeutics based on inhibiting the activation of TGFß signalling may prove useful in the treatment of OSCC.

Oral leukoplakia-to treat or not to treat.

Various treatment modalities have been described for reducing or eliminating malignant development of oral leukoplakia, but no treatment has gained universal approval due to lack of randomized clinical studies. At present, it is uncertain whether we can do harm to the patients by treating or by not treating them. An essential aspect is the observation of cancer development even after surgical removal of the clinical lesions. Inadequate resection of the lesions or field cancerization may account for this phenomenon. Another challenge is whether surgical removal of the lesions in fact is associated with a cancer promotional effect resulting in increased risk of cancer. Moreover, unidentified existing cancer in non-suspicious oral leukoplakias may for diagnostic purposes imply that surgical removal is recommendable as well as serial section of all excised tissue. Intensive follow-up programmes for leukoplakias are important, independent of surgical intervention.

TP53 mutations in clinically normal mucosa adjacent to oral carcinomas.

BACKGROUND: The tumour-suppressor protein p53 often accumulates in histologically normal epithelium adjacent to oral squamous cell carcinomas (OSCC). We investigated whether this was associated with mutations in TP53, the gene for p53, and might implicate impending malignancy. METHODS: Specimens from 18 human squamous cell carcinomas were stained with monoclonal p53 antibodies. Positive cells were microdissected with laser-captured microscopy from the tumour and adjacent normal and dysplastic epithelium. DNA was extracted, and exons 5-9 of the TP53 gene were amplified by PCR. Amplified products were separated by denatured gradient gel electrophoresis. Fragments with a deviant DGEE pattern were sequenced. RESULTS: TP53 mutations were found in six of 18 tumours. Fourteen specimens contained histologically normal mucosa adjacent to the tumour; 13 of these showed small clusters of p53 positive cells. Seven specimens contained both histological normal and dysplastic epithelial tissues adjacent to the tumour. A TP53 mutation was found in only one specimen; this mutation appeared in the normal mucosa, the adjacent tumour, and the epithelial dysplasia. CONCLUSION: We found that upregulation of p53 was a frequent event in histological normal mucosa adjacent to OSCC; however, it was rarely associated with a mutation in the TP53 gene.

Oral epithelial dysplasia classification systems: predictive value, utility, weaknesses and scope for improvement.

At a workshop coordinated by the WHO Collaborating Centre for Oral Cancer and Precancer in the United Kingdom issues related to potentially malignant disorders of the oral cavity were discussed by an expert group. The consensus views of the Working Group are presented in a series of papers. In this report, we review the oral epithelial dysplasia classification systems. The three classification schemes [oral epithelial dysplasia scoring system, squamous intraepithelial neoplasia and Ljubljana classification] were presented and the Working Group recommended epithelial dysplasia grading for routine use. Although most oral pathologists possibly recognize and accept the criteria for grading epithelial dysplasia, firstly based on architectural features and then of cytology, there is great variability in their interpretation of the presence, degree and significance of the individual criteria. Several studies have shown great interexaminer and intraexaminer variability in the assessment of the presence or absence and the grade of oral epithelial dysplasia. The Working Group considered the two class classification (no/questionable/ mild - low risk; moderate or severe - implying high risk) and was of the view that reducing the number of choices from 3 to 2 may increase the likelihood of agreement between pathologists. The utility of this need to be tested in future studies. The variables that are likely to affect oral epithelial dysplasia scoring were discussed and are outlined here; these need to be researched in longitudinal studies to explore the biological significance of a low-risk or high-risk dysplasia.

Expression of Ricinus communis receptors on epithelial cells in oral carcinomas and oral wounds.

The histological distribution of receptors for Ricinus communis Fraction 1 (RCA1) in oral carcinomas and in oral epithelial cells during wound healing has been studied by use of fluorescein-tagged RCA1. Biopsies from 15 human oral carcinomas and adjacent normal mucosa showed RCA1 receptors at the cell membranes in the basal and spinous layer of the normal epithelium, whereas receptors could not be demonstrated in invading islands of the tumors. In healing oral wounds from eight humans and three monkeys, RCA1 receptors were demonstrated both in normal epithelium adjacent to the wounds and in the epithelial outgrowth from the wound margin. Titrations, however, showed that the epithelial outgrowth reacted more weakly than did the normal adjacent epithelium. These results support previous in vitro studies showing changes in carbohydrate composition of moving normal cells and of malignant cells, a finding that may be of interest in relation to formation of metastases.

Structural variations of blood group A antigens in human normal colon and carcinomas.

The blood group A determinant is carried by four basic carrier carbohydrate chains. This paper reports the expression of blood group A variants, as determined by immunohistology with highly specific monoclonal anti-A antibodies, in 18 adenocarcinomas of the distal colon, 4 specimens of normal proximal mucosa from group A persons, and 5 specimens of fetal colonic mucosa. Monoclonal antibodies directed to type 1 chain A, type 1 chain ALeb, type 2 chain A, type 2 chain ALey, and type 3 chain A (repetitive A) were used. In normal mucosa, type 1 chain A and ALeb were expressed in proximal regions. Type 1 chain A was expressed in columnar cells, whereas type 1 chain ALeb was found in goblet cells. Type 2 and type 3 chain A structures were not found in normal adult mucosa. All types of A antigens were detected in adenocarcinomas from the distal colon as well as in normal fetal mucosa. In fetal mucosa, type 1 chain A and ALeb antigens and type 3 chain A antigens were expressed in columnar cells, whereas type 2 chain A and Ley and type 1 chain ALeb antigens were found in goblet cells. The results indicate that blood group A antigens with type 1, 2, and 3 carriers are present in fetal mucosa and adenocarcinomas of distal colon, while epithelial mucosa of normal adult colon is characterized by the exclusive expression of type 1 chain A antigens.

Accumulation of a blood group antigen precursor in oral premalignant lesions.

Epithelial cell membrane-bound blood group antigens A and B are lost in premalignant and malignant oral lesions. We now show that this loss in premalignant lesions is accompanied by accumulation of a blood group antigen precursor. The precursor structures were: type 2 chain H-antigen, Fuc alpha 1 leads to 2 Gal beta 1 leads to 4 GlcNAc-R (A and B precursor); and N-acetyllactosamine, Gal beta 1-4GlcNAc-R (H-precursor), in which Fuc is L-fucose, Gal is galactose, and GIcNAc is N-acetyl-D-glucosamine. They were demonstrated in tissue sections by immunohistochemical staining techniques with monoclonal antibodies to H-antigen and N-acetyllactosamine. Precursors were found only on basal and suprabasal cells of normal mucosa. In all nine of ten premalignant lesions, the H-antigen was found on all cell membranes in the epithelium, in higher titers than in normal adjacent epithelium. Ten carcinomas were studied, and all showed an irregular distribution of H-antigen. N-Acetyllactosamine was not found in premalignant or malignant lesions. The accumulation of type 2 chain H-antigen in oral premalignant lesions may prove helpful in early diagnosis of epithelial cancer.

Loss of a novel mucin-like epithelial glycoprotein in oral and cervical squamous cell carcinomas.

Stratified squamous epithelia of oral and cervical mucosa express high levels of simple mucin-type O-linked carbohydrates, and these are known to undergo structural changes in relation to epithelial differentiation and neoplastic transformation. O-glycans in these epithelia are associated with the cell membrane, but the identity of the carrier molecule(s) remains largely unknown. We report here the identification of a membrane-bound M(r) 200,000-250,000 glycoprotein (gp230) that is expressed in stratified squamous epithelia of the oral cavity. Western blot analysis identified gp230 as a major carrier of simple-mucin type carbohydrate antigens in buccal nonkeratinized mucosal epithelium, suggesting that it may represent a mucin-like molecule. A monoclonal antibody PANH4 defining a protein epitope of gp230 was generated. The PANH4 epitope was localized by immunohistology to suprabasal cell layers of buccal epithelium and was also found in larynx, esophagus, vagina, and exocervix, but not in epidermis. Data showed that gp230 was distinct from MUC1 or CD44. It is interesting that in most cases gp230 was not expressed in squamous cell carcinomas of buccal and cervical mucosa. A few moderately differentiated carcinomas, mainly from cervix, expressed the gp230 epitope. The results suggest that a membrane-bound mucin-like molecule, gp230, is associated with the differentiated phenotype of normal mucosal stratified squamous epithelia and that expression of gp230 generally is lost in severe oral epithelial dysplasia and squamous cell carcinomas of oral and cervical mucosa.

Biosynthetic basis of incompatible histo-blood group A antigen expression: anti-A transferase antibodies reactive with gastric cancer tissue of type O individuals.

The expression of incompatible A carbohydrate antigens in some adenocarcinomas may provide an explanation for the generally observed lower incidence of adenocarcinoma among types O and B versus type A individuals. The chemistry and genetic basis of incompatible A expression is largely unknown. Here, we have screened 31 cases of gastric tumors of phenotype O for the expression of blood group A gene-defined glycosyltransferase by immunohistology on frozen sections using newly developed monoclonal antibodies to the transferases. Three cases were positive, and transferase expression was confirmed by enzyme analysis of extracts from the specimens. Blood group A carbohydrate antigens were also identified immunohistologically in these three cases as well as in five other cases. Thin-layer chromatography immunostaining analysis of glycolipid extracts from the three cases did not confirm the chemical presence of A antigen. The ABO genotype of all patients was found to be OO, showing that all carried O alleles with a structural defect at nucleotide position 261 leading to a shift in the reading frame. The data suggest that incompatible A antigen expression is a result of transferase expression derived from the ABO genes.

Immunoelectrophoretic studies on pig intestinal brush border proteins.

Brush borders were prepared from pig intestinal mucosa and the membrane proteins solubilized with either Triton X-100 or papain. Proteins, thus released, were used as antigens to raise antisera in rabbits. The immunoglobulin G fractions were isolated and shown by the double layer immunofluorescence staining technique to react only with the brush border region of the enterocyte. The antibodies obtained were used in immunoelectrophoretic studies on the brush border proteins. Eight hydrolytic activities were identified by the use of histo-chemical staining methods. These were the microsomal aminopeptidase (EC 3.4.11.2), aspartate aminopeptidase (EC 3.4.11.7), dipeptidyl peptidase IV (EC 3.4.14.X), lactase (EC 3.2.1.23), glucoamylase (EC 3.2.1.3), sucrase (EC 3.2.1.48), isomaltase (EC 3.2.1.10) and alkaline phosphatase (EC 3.1.3.1). In addition, at least four faint immunoprecipitates were formed but none of these were identified.

ABO blood-group antigens in oral cancer.

Tumor progression is often associated with altered glycosylation of the cell-surface proteins and lipids. The peripheral part of these cell-surface glycoconjugates often carries carbohydrate structures related to the ABO and Lewis blood-group antigens. The expression of histo-blood-group antigens in normal human tissues is dependent on the type of differentiation of the epithelium. In most human carcinomas, including oral carcinoma, a significant event is decreased expression of histo-blood-group antigens A and B. The mechanisms of aberrant expression of blood-group antigens are not clear in all cases. A relative down-regulation of the glycosyltransferase that is involved in the biosynthesis of A and B antigens is seen in oral carcinomas in association with tumor development. The events leading to loss of A transferase activity are related, in some instances, to loss of heterozygosity (LOH) involving chromosome 9q34, which is the locus for the ABO gene, and in other cases, to a hypermethylation of the ABO gene promoter. The fact that hypermethylation targets the ABO locus, but not surrounding genes, suggests that the hypermethylation is a specific tumor-related event. However, since not all situations with lack of expression of A/B antigens can be explained by LOH or hypermethylation, other regulatory factors outside the ABO promoter may be functional in transcriptional regulation of the ABO gene. Altered blood group antigens in malignant oral tissues may indicate increased cell migration. This hypothesis is supported by studies showing that normal migrating oral epithelial cells like malignant cells show lack of expression of A/B antigens, and by studies that target ABH antigens to key receptors controlling adhesion and motility, such as integrins, cadherins, and CD-44.

HGF is released from buccal fibroblasts after smokeless tobacco stimulation.

To investigate the effect of smokeless tobacco (ST) on (1) HGF, KGF and GM-CSF expression by buccal fibroblasts and (2) on keratinocyte and fibroblast proliferation. Buccal fibroblasts were stimulated with different concentrations of ST extracts in a double dilution from 0.50% w/v to 0.03% w/v. Supernatant was collected after 24/48/72/96 h and assayed for HGF, KGF, and GM-CSF by ELISA. The amount of RNA was used as an indicator of fibroblast cell number. Buccal epithelial cell proliferation was determined by CyQUANT proliferation assay. The amount of HGF and KGF in the supernatant was dependent on exposure time and on concentration of the tobacco extract. High concentration increased production of HGF 4-fold. KGF production was doubled when high concentration of tobacco was used, low concentration did not stimulate cells. GM-CSF production was low in both stimulated and non-stimulated cells. Keratinocytes and fibroblasts showed no increase in proliferation after stimulation with increased concentrations of ST. The results suggest that HGF and KGF may play an important role as a paracrine growth factor in epithelial hyperplasia in ST lesions.

Immunomicroscopic localization of aminopeptidase N in the pig enterocyte. Implications for the route of intracellular transport.

The subcellular localization of aminopeptidase N (EC 3.4.11.2) in the pig enterocyte was investigated by immunofluorescence and immunoelectron microscopy (immunogold staining). By indirect immunofluorescence on either frozen or paraffin-embedded sections, a very intense staining in the microvillar membrane and a weak intracellular staining was demonstrated. No staining was detected in the basolateral membrane. Likewise, the immunogold labelling on Epon-embedded sections was concentrated in the microvillar membrane, whereas the basolateral membrane did not contain significant amounts of labelling. Labelling was demonstrated in the Golgi apparatus and in a minor fraction of the intracellular smooth vesicles positioned between the Golgi apparatus and the microvillar membrane. These observations are compatible with the view that newly synthesized aminopeptidase N is delivered directly to the microvillar membrane by smooth vesicles having a diameter about 70 to 100 nm and does not pass the basolateral membrane on its way to the brush border membrane.

Changes in carbohydrate expression of lichen planus affected oral epithelial cell membranes.

The purpose of the present study was to examine possible epithelial cell membrane changes in lichen planus affected oral mucosa by the use of the lectins concanavalin-A and ricinus communis agglutinin fraction I. It was shown that these lectins in contrast to what was found in normal epithelium do not bind to the cell membranes of basal cells of lichen planus affected epithelium. The lack of binding of lectins suggests changes in exposed carbohydrates at the surfaces of the cells. The findings may support the hypothesis of antigenic changes in the lichen planus affected epithelium.

A model for the study of autoimmune diseases applied to pemphigus: transplants of human oral mucosa to athymic nude mice binds pemphigus antibodies in vivo.

The present paper describes a new in vivo method to study the action of pemphigus antibodies against human tissue. Oral mucosal biopsies from healthy donors were transplanted to athymic nude mice, which, a week later, were injected with serum from pemphigus patients. From 1 to 5 days after the injection the epithelial transplants were removed and preparations were studied by immunofluorescence microscopy. Pemphigus antibodies were demonstrated in preparations from each of 23 mice which had received pemphigus serum, but in none of 6 which had received control serum. Transplants from about 2/3 of the experimental mice showed intercellular edema of the basal layers of the epithelium and in transplants from 3 mice supra-basilar splitting of the epithelium was found. None of these changes was seen in the control mice. Passive transfer of human serum or lymphocytes to nude mice transplanted with human tissue may be use in future studies of autoimmune diseases, including pemphigus.

Cell surface carbohydrate changes during embryonic and fetal skin development.

Monoclonal antibodies to four type 2 chain carbohydrate antigens were used for immunohistochemical studies of embryonic and fetal skin. The antibodies detected N-acetyllactosamine and 3 fucosyl substitutes of this, blood group antigen H, Lex, and Ley. Periderm consistently stained for N-acetyllactosamine, Lex and Ley. The H antigen showed a variable and weak expression on peridermal cells from day 57 to day 84 estimated gestation age (EGA). After this period the H antigen was no longer expressed at peridermal cells. In the epidermis, N-acetyllactosamine was present on all cells until the age of 15 weeks EGA. After this period N-acetyllactosamine could only be demonstrated on basal cells after treatment with neuraminidase, indicating a masking of N-acetyllactosamine by sialic acid. The H antigen could not be demonstrated in the epithelium before 14 weeks EGA. At this time it appeared on spinous and granular cells in the epithelium. Lex stained both basal cells and intermediate cells positively, until keratinization around week 20 EGA. Ley is never expressed on basal cells. It is weakly expressed by intermediate cells from week 14 EGA. Our study demonstrates that N-acetyllactosamine is maximally expressed at the early stages of development, but may later be modified either by sialylation or fucosylation into blood group H or Lex, or by Ley substances, respectively. The orderly and well-defined changes observed during skin differentiation are in agreement with other studies, which have demonstrated the existence of chemically defined cell surface changes accompanying cell differentiation.

Altered expression of epithelial cell surface glycoconjugates and intermediate filaments at the margins of mucosal wounds.

Alterations in cell to cell adhesion are necessary to enable the type of cell movements that are associated with epithelial wound healing and malignant invasion. Several studies of transformed cells have related epithelial cell movement to changes in the cell surface expression of the carbohydrate structures represented by the ABO blood group antigens and, in particular, by Lewis antigens and their biosynthetic precursors. To study further the relationship between cell surface carbohydrates and keratinocyte cell movement, experimental wounds were created in human oral mucosa and examined by immunohistochemical methods for their expression of selected cytokeratins (K5, K16, K19), basement membrane components (laminin alpha5 and gamma2-chains, BP180, collagen IV and collagen VII), and blood group antigen precursor structures Le(x), sialosyl-Le(x), Le(y), H antigen, N-acetyllactosamine, and sialosyl-T antigen. The changes induced by wounding in the expression of collagen IV, laminin gamma2-chain (laminin-5), and laminin alpha5-chain were similar to those found in skin wounds and served to define the region of epithelial movement. This region was found to show a marked increase in staining for both Lewis antigen Y (Le(y)) and H blood group antigen, and decreased staining of Le(x), thus indicating an upregulation in wounded epithelium of the fucosyltransferases responsible for the synthesis of the H antigen. The changes in carbohydrate expression extended beyond the wound margin into the nonwounded epithelium, a pattern of expression similar to K16, which was also strongly upregulated in both the outgrowth and the adjacent nonwounded epithelium. These findings provide further support for an influence of such carbohydrate structures on the migratory behavior of epithelial cells.

The production of antibodies to cell membranes of squamous epithelium by the use of aldehyde-induced membrane vesicles.

A new method for the isolation of plasma membrane residues which can be used to raise antibodies to oral epithelial cell membranes is described. Plasma membrane vesicles were formed on the cell surfaces of confluent rat oral epithelial cell cultures by exposing the cells in situ to 100 mM freshly prepared formaldehyde. The vesicles formed 10--15 min. after exposure and were released into the medium. The vesicles, 1--10 micrometers in diameter, were sedimented by centrifugation at 30,000 g for 20 min. Antibodies to vesicles were raised in rabbits and used in an indirect immunofluorescence and immunoperoxidase staining technique. In rat and human oral epithelium they stained cell membranes in the basal and spinous cell layers. No cytoplasmic staining was seen in the epithelium. Staining of squamous epithelium from the human uterine cervix, rat and human skin and guinea pig lip was negative.

Concanavalin A and ricinus communis receptor sites in normal human oral mucosa.

Fluorescein conjugates of concanavalin A (Con-A) and Ricinus communis fraction 120 (RCA120) were shown to bind to the cell surfaces of basal and spinous cell layers in oral buccal mucosa. Palatal epithelium showed distinct binding to basal and spinous cells; cell membranes in the granular layer occasionally bound Con-A and always RCA120. The ultrastructural localization of Con-A binding sites on exfoliated buccal cells was detected by the Con-A peroxidase staining method. The Con-A receptors were seen on the cell surface in association with the outer leaflet of the plasma membrane. The reaction products appeared as a homogeneous, electron-dense layer containing irregularly distributed globules.

Pattern of distribution of blood group antigens on human epidermal cells during maturation.

The distribution in human epidermis of A, B, and H blood group antigens and of a precursor carbohydrate chain, N-acetyl-lactosamine, was examined using immunofluorescence staining techniques. The material included tissue from 10 blood group A, 4 blood group B, and 9 blood group O persons. Murine monoclonal antibodies were used to identify H antigen (type 2 chain) and N-acetyl-lactosamine. Human antisera were used to identify A and B antigens. In all groups N-acetyl-lactosamine and H antigen were found on the cell membranes of the spinous cell layer. N-acetyl-lactosamine was present mainly on the lower spinous cells whereas H antigen was seen predominantly on upper spinous cells or on the granular cells. Epithelia from blood group A or B persons demonstrated A or B antigens, respectively, but only if the tissue sections were trypsinized before staining. In such cases A or B antigens were found on the cell membranes in the granular cell layer.