Expression of human cytokeratin 14 in normal, premalignant and malignant oral tissue following isolation by plaque differential hybridisation

Utility of Keratins as Biomarkers for Human Oral Precancer and Cancer

Human oral cancer is the single largest group of malignancies in the Indian subcontinent and the sixth largest group of malignancies worldwide. Squamous cell carcinomas (SCC) are the most common epithelial malignancy of the oral cavity, constituting over 90% of oral cancers. About 90% of OSCCs arise from pre-existing, potentially malignant lesions. According to WHO, OSCC has a 5-year survival rate of 45–60%. Late diagnosis, recurrence, and regional or lymph nodal metastases could be the main causes of the high mortality rates. Biomarkers may help categorize and predict premalignant lesions as high risk of developing malignancy, local recurrence, and lymph nodal metastasis. However, at present, there is a dearth of such markers, and this is an area of ongoing research. Keratins (K) or cytokeratins are a group of intermediate filament proteins that show paired and differentiation dependent expression. Our laboratory and others have shown consistent alterations in the expression patterns of keratins in both oral precancerous lesions and tumors. The correlation of these changes with clinicopathological parameters has also been demonstrated. Furthermore, the functional significance of aberrant keratins 8/18 expression in the malignant transformation and progression of oral tumors has also been documented. This article reviews the literature that emphasizes the value of keratins as biomarkers for the prognostication of human oral precancers and cancers.

Immunohistochemical staining patterns of cytokeratins 13, 14, and 17 in oral epithelial dysplasia including orthokeratotic dysplasia

Diagnosis of the exact grade of oral epithelial dysplasia is difficult, and interobserver variations in grading are common. The aim of this study was to investigate the expression patterns of cytokeratins (CKs) in dysplastic oral epithelia, to identify useful double immunostaining diagnostic markers. Immunoexpression of CK13, CK14, CK17, and Ki-67 were investigated in 21 normal epithelial specimens and 146 epithelial dysplasia specimens. In epithelial dysplasia specimens, orthokeratotic dysplasia (OKD) was identified using CK10 immunostaining. Most mild dysplasia specimens were CK13+ and CK17-. In moderate dysplasia, CK13 expression tended to be lower and CK17 expression tended to be higher than in mild dysplasia. All carcinoma in situ (CIS) specimens were CK17+. In differentiated type CIS specimens, CK13 expression was weakly positive. Most epithelial dysplasia specimens were CK14+. There were no significant differences in the expression patterns of CKs between OKD and non-OKD specimens in any of the grades of dysplasia. These results indicate that CK14 expression can be used to detect early epithelial dysplasia, and that CK13 and CK17 expression are useful for detecting neoplastic changes.

Keratin 5 expression in squamocellular carcinoma of the head and neck

Keratin 5 (K5) is present in the basal layer of a stratified squamous keratinized and non-keratinized epithelium. K5 and K14 have been demonstrated in the mucosa and tumors of the oral cavity, oropharynx, hypopharynx and larynx, and in the mitotic active basal cells of a stratified squamous epithelium. The aim of the present study was to assess K5 expression in squamocellular carcinoma with various localizations in the head and neck. A total of 13 biopsy fragments were included from patients diagnosed with squamocellular carcinoma of the larynx area (n=2), pharynx (n=2), hard palate (n=1), tongue (n=2), submandibular (n=1), lip (n=1), gingival sulcus (n=1), nasal pyramid (n=1), maxilla (n=1) and zygomatic (n=1). The immunohistochemical staining for K5 was evaluated according to the following score criteria: 0 (0% positive cells); 1 (<10% positive cells); 2 (10-30% positive cells); and 3 (>30% positive cells). K5 expression was observed in all squamocellular carcinomas included in the present study with scores between 1 and 3. For well- and moderately-differentiated histopathological types, a maximum score of 3 was recorded for all of the cases, not including the laryngeal area, which presented a score of 2. The following scores were identified in the regions of the poorly differentiated carcinomas: Jaw, 3; gingival sulcus, 2; and tongue and submandibular area, 1. These observations may aid with an improved stratification of head and neck squamocellular carcinoma, thus improving the diagnosis and treatment strategies for this type of cancer.

Comprehensive transcriptome profiling of squamous cell carcinoma of horn in Bos indicus

Squamous cell carcinoma (SCC) of horn is frequently observed in Bos indicus affecting 1% of cattle population and accounting 83.34% of total tumours found. The transcriptome profile of horn cancer (HC) tissue and the matched normal (HN) tissue were analysed by RNA-seq using Roche 454 sequencing. A total of 1 504 900 reads comprising of 612 MB data were used to identify differentially expressed genes using CLC Genomic Workbench. These include up-regulation of KRT6A, KRT6B, KRT6C, KRT14, SFN, KRT84, PI3, COL17A1, ANLN, SERPINB5 and down-regulation of BOLA, SCGB1A1, CXCL17, KRT19, BPIFB1, NR4A1 and TFF3 in HC, which are involved in regulation of gene transcription, cell proliferation, apoptosis, cell survival and metabolic pathways. The qPCR analysis of several targets suggested concordance of gene expression profile with RNA-seq analysis. The present findings would provide basis for further screening of genes and identification of markers for early diagnosis and therapeutic intervention of HC.

Gene expression analysis of SCC tumor cells in muscle tissue

The purpose of this study was to evaluate microarray technology of HNSCC cells in muscle tissue. 200 SCCVII tumor cells were injected intramuscularly into the right flank of ten C3H/Km mice each. One week later the animals were killed and the tissue taken out. Histology (H&E staining) and microarray of the tissue were performed. Histology showed a few tumor cells between the muscle fibers. Microarray technology showed different gene expression pattern of the muscle tissue with SCCVII cells in comparison with normal muscle tissue. Only those genes showing a fold change difference of 5 or higher were considered. Gene expression analysis revealed changes in the expression levels of SCCVII cells in muscle tissue in 220 genes. Significant gene expression differences between SCCVII cells in muscle tissue and pure muscle tissue could be seen.

Detection of metastatic head and neck squamous cell carcinoma using the relative expression of tissue-specific mir-205

The presence of cervical lymph node metastases in head and neck squamous cell carcinoma (HNSCC) is the strongest determinant of patient prognosis. Owing to the impact of nodal metastases on patient survival, a system for sensitive and accurate detection is required. Clinical staging of lymph nodes is far less accurate than pathological staging. Pathological staging also suffers limitations because it fails to detect micrometastasis in a subset of nodal specimens. To improve the sensitivity of existing means of diagnosing metastatic disease, many advocate the use of molecular markers specific for HNSCC cells. MicroRNA (miRNA) are short noncoding segments of RNA that posttranscriptionally regulate gene expression. Approximately one third of all miRNA will exhibit substantial tissue specificity. Using a quantitative reverse transcription-polymerase chain reaction-based assay, we examined the expression of microRNA-205 (mir-205) across tissues and demonstrated that its expression is highly specific for squamous epithelium. We applied this assay to tissue samples, and we could detect metastatic HNSCC in each positive lymph node specimen, whereas benign specimens did not express this marker. When compared to metastases from other primary tumors, HNSCC-positive lymph nodes were distinguishable by the high expression of this marker. Using an in vitro lymphoid tissue model, we were able to detect as little as one squamous cell in a background of 1 million lymphocytes. By combining the sensitivity of quantitative reverse transcription-polymerase chain reaction with the specificity of mir-205 for squamous epithelium, we demonstrate a novel molecular marker for the detection of metastatic HNSCC.

The keratin-14 expression in actinic keratosis and squamous cell carcinoma: is this a prognostic factor for tumor progression?

PURPOSE

Actinic keratosis (AK) is an incipient form of cutaneous squamous cell carcinoma (SCC). We determined if the pattern of expression of keratin-14 (K14) is a factor for tumor progression in AK and SCC.

MATERIALS AND METHODS

Eighteen sections from the tissues of 16 patients were stained with anti-K14 antibody and p16(INK4a). Among the 16 patients, 4 were diagnosed with both SCC and AK at the same site, but AK developed first and SCC developed subsequently. Thus, SCC may have evolved from AK. The other 12 patients were only diagnosed with AK.

RESULTS

In all of the AK and SCC tissues, basement membranes showed positive staining for K14. However, strong reactivities were shown in the spinous and granular layers and focuses of dermal invasion in the SCC tissues developed from AK. Two and 3 of the 12 AK cases had moderately positive reactions for K14 in the spinous and granular layers, respectively. Also, all SCC tissues except one had moderate-to-strong reactions in the basal, spinous, and granular layers for p16(INK4a). Two of the 12 AK cases had weak-to-moderate positive reactions in the basal, spinous, and horny layers for p16(INK4a).

CONCLUSION

The results of our study advance our understanding of the pathogenesis of SCC developing from AK. The results also indicate a differential role in the control of K14 in normal epithelia, AK, and SCC. K14 expression in the spinous and granular layers may be a prognostic factor for tumor progression of AK.

Differential expression of the keratin-4, -13, -14, -17 and transglutaminase 3 genes during the development of oral squamous cell carcinoma from leukoplakia

To identify differentially expressed genes during the development of oral malignancy, differential display, northern blotting, reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical analyses were undertaken using oral squamous cell carcinoma (OSCC) and leukoplakia tissues. Significantly higher levels of keratin (Ker)-14 and -17 mRNAs, combined with lower levels of Ker-4, Ker-13 and transglutaminase 3 (TG-3) transcripts, were observed in OSCC and severely dysplastic tissues, whereas this expression profile was reversed in hyperplasia and in mild to moderate dysplasia. The expression of Ker-4 and Ker-13 was elevated in density-arrested OSCC cell lines (Ca9-22, HSC-2, -3 and -4) but the expression of Ker-17 mRNA was elevated in these cells, regardless of the growth conditions. In addition, Ker-4 and Ker-13 proteins were predominantly expressed in moderate dysplasia and hyperplasia, whereas Ker-17 was markedly expressed in OSCC tissues. The expression patterns of these genes could therefore be an important determinant of the manifestation of oral malignancy.

Database on monoclonal antibodies to Cytokeratins

Cytokeratins (CK) are being extensively used as diagnostic markers for various malignancies and other diseases, including human oral precancer and cancer, due to their tissue specific expression. CK are epithelia specific intermediate filament (IF) proteins, which are expressed in a differentiation dependent and tissue specific manner. There are about 30 polypeptides of CK expressed by different human epithelia. Each type of epithelium expresses about 4-6 polypeptides. CK polypeptides share many common epitopes, due to which the antibodies developed against CK tend to cross react. Therefore, a large number of monoclonal and polyclonal antibodies have been developed to distinguish among these proteins. Many of these antibodies are not only monospecific but are also epitope specific. These antibodies are being used in pathology laboratories for routine diagnosis using immunohistochemistry. A number of fixatives are used for fixation of tissue sections prior to the use of these antibodies. Sometimes, this leads in epitope masking. Hence, it becomes necessary to use a battery of monoclonal antibodies (MAb) for accurate diagnosis. Apart from the use of these antibodies in diagnostics, they are also being used in basic research for the study of CK function and their interactions with associated proteins and membrane proteins. In the present communication an effort has been made to make a comprehensive list of MAb to CK giving information like cross-reactivity, epitope specificity, various fixatives used, etc. along with the source of the antibodies, which will provide useful information to the users.

A comparison of the management of potentially malignant oral mucosal lesions by oral medicine practitioners and oral & maxillofacial surgeons in the UK

This study describes the results of a survey undertaken to assess the management of potentially malignant oral mucosal lesions by oral medicine practitioners and compares their approach with that of oral & maxillofacial surgeons that we have previously described. Significant differences were noted between the two groups in the use of photography to document the lesions and in the use of certain special investigations, which included measurement of serum iron, serum ferritin, serum Vit B12, red cell folate and candidal isolation. The groups also varied in the perceived importance of the age of the patient and anatomical site of the lesion when deciding on the need for further biopsy. There was also significant variation in the use of certain treatment modalities, including excising non-dysplastic and severely dysplastic/carcinoma in-situ lesions and eliminating trauma when treating mild/moderately dysplastic and severely dysplastic/carcinoma in-situ lesions. Significant differences in the frequency and duration of follow-up were noted for non-dysplastic lesions. Finally, the two groups differed significantly when asked to rank the perceived importance of certain factors (the histopathology of the most recent biopsy and the anatomical site of the lesion) when deciding the need to follow-up. Possible reasons for the variation are discussed.

Keratin 14 and 19 expression in normal, dysplastic and malignant oral epithelia. A study using in situ hybridization and immunohistochemistry

Specific mRNA and protein for two major keratins, K14 and K19, were investigated in normal, dysplastic and malignant oral epithelia by combined in situ hybridization and immunohistochemistry. In normal epithelia, K14 mRNA and protein were present almost exclusively in the basal layer of non-cornified, and in rete-processes of cornified, sites. Dysplastic epithelium showed irregular extension of the K14 transcript and protein into superficial cells. In squamous cell carcinoma (SCC), K14 transcript was abundant in most samples whilst in one poorly differentiated carcinoma mRNA but no protein was detected. K19 mRNA and its protein were present predominantly in basal cells of noncornified epithelium, whereas in cornified epithelium only mRNA was detected. In dysplasias, K19 transcript was detected in all specimens but its protein was absent in most cases. Even more variations of K19 expression were observed in SSC. These findings indicate differences in the control of expression of K14 and K19 in normal epithelia and show that regulation is further disturbed during dysplastic change and malignancy.

Cloning of putative growth regulatory genes from primary human keratinocytes by subtractive hybridization

In order to isolate genes that might be involved in regulating human keratinocyte (HKc) growth and/or differentiation, we constructed a cDNA library by subtractive hybridization between primary HKc and FaDu head-and-neck squamous cell carcinoma cells. Among the first set of independent cDNAs that we have isolated, ten correspond to known genes, and two represent novel sequences. Nine of the ten known genes are expressed at significantly lower levels in the majority of the SqCC cell lines in comparison with primary HKc. These include cDNAs that encode keratins K5 and K14 which are cytoskeletal proteins normally expressed in lining epithelia, the 14-3-3 protein stratifin/HME-1, lipocortin-II and CaN19 which are calcium-binding proteins that may play a role in HKc differentiation by regulating protein kinase C, plasminogen-activator inhibitor-2 which is a serine-proteinase inhibitor, HBp17 which is a HKc-specific secreted inhibitor of fibroblast growth factors, integrin alpha 3 which plays a role in the anchoring of keratinocytes to basement membrane, and YL-8, a ras-like protein that probably mediates intracellular protein trafficking. In addition, we isolated two cDNAs, LIS-1 which encodes the 45-kDa intracellular subunit of the platelet-activating factor acetyl-hydrolase, and the unknown sequence HFBCB84 which showed reduced expression in only a small number of tumor lines as compared to HKc. Inactivation or loss of any of these proteins may confer a selective advantage onto squamous epithelial cells and contribute to their malignant transformation.