Gene expression of differentiation-specific keratins in oral epithelial dysplasia and squamous cell carcinoma

Effect of Skin Barrier on Atopic Dermatitis

The skin acts as the body's primary physical and immune barrier, maintaining the skin microbiome and providing a physical, chemical, and immune barrier. A disrupted skin barrier plays a critical role in the onset and advancement of inflammatory skin conditions such as atopic dermatitis (AD) and contact dermatitis. This narrative review outlines the relationship between AD and skin barrier function in preparation for the search for possible markers for the treatment of AD.

Exploring the Functions of Mutant p53 through TP53 Knockout in HaCaT Keratinocytes

Approximately 50% of tumors carry mutations in TP53; thus, evaluation of the features of mutant p53 is crucial to understanding the mechanisms underlying cell transformation and tumor progression. HaCaT keratinocytes represent a valuable model for research in this area since they are considered normal, although they bear two gain-of-function mutations in TP53. In the present study, transcriptomic and proteomic profiling were employed to examine the functions of mutant p53 and to investigate the impact of its complete abolishment. Our findings indicate that CRISPR-mediated TP53 knockout results in significant changes at the transcriptomic and proteomic levels. The knockout of TP53 significantly increased the migration rate and altered the expression of genes associated with invasion, migration, and EMT but suppressed the epidermal differentiation program. These outcomes suggest that, despite being dysfunctional, p53 may still possess oncosuppressive functions. However, despite being considered normal keratinocytes, HaCaT cells exhibit oncogenic properties.

KRT13 and UPK1B for differential diagnosis between metastatic lung carcinoma from oral squamous cell carcinoma and lung squamous cell carcinoma

Oral squamous cell carcinomas unusually show distant metastasis to the lung after primary treatment, which can be difficult to differentiate from primary squamous cell carcinoma of the lung. While the location and number of tumor nodules is helpful in diagnosing cases, differential diagnosis may be difficult even with histopathological examination. Therefore, we attempted to identify molecules that can facilitate accurate differential diagnosis. First, we performed a comprehensive gene expression analysis using microarray data for OSCC-LM and LSCC, and searched for genes showing significantly different expression levels. We then identified KRT13, UPK1B, and nuclear receptor subfamily 0, group B, member 1 (NR0B1) as genes that were significantly upregulated in LSCC and quantified the expression levels of these genes by real-time quantitative RT-PCR. The expression of KRT13 and UPK1B proteins were then examined by immunohistochemical staining. While OSCC-LM showed no KRT13 and UPK1B expression, some tumor cells of LSCC showed KRT13 and UPK1B expression in 10 of 12 cases (83.3%). All LSCC cases were positive for at least one of these markers. Thus, KRT13 and UPK1B might contribute in differentiating OSCC-LM from LSCC.

The increased expression of cytokeratin 13 leads to an increase in radiosensitivity of nasopharyngeal carcinoma HNE-3 cells by upregulating ERRFI1

The main factors contributing to the unfavorable outcome in the clinical treatment of patients with nasopharyngeal carcinoma (NPC) patients are radiation resistance and recurrence. This study aimed to investigate the sensitivity and molecular foundation of cytokeratin 13 (CK13) in the radiotherapy of NPC. To achieve this, a human NPC cell line overexpressing CK13, HNE-3-CK13, was constructed. The effects of CK13 overexpression on cell viability and apoptosis under radiotherapy conditions were evaluated using the CCK-8 assay, immunofluorescence, and western blotting (WB). Next-generation sequencing was performed to identify the downstream genes and signaling pathways of CK13 that mediate radiotherapy response. The potential role of the candidate gene ERRFI1 in CK13-induced enhancement of radiosensitivity was investigated through rescue experiments using clone formation and WB. The effects of ERRFI1 on cell viability, cell apoptosis, cell cycle, and the related key genes were further evaluated using CCK-8, immunofluorescence, flow cytometry, quantitative polymerase chain reaction and WB. The results showed that CK13 overexpression in HNE-3 significantly inhibited cell survival under radiotherapy and promoted apoptosis marker γH2AX expression, leading to a significant increase of ERRFI1. Knockdown of ERRFI1 rescued the decreased cell viability and proliferation and the increased cell apoptosis that were caused by CK13 overexpression-mediated radiotherapy sensitization of NPC cells. In this process, EGFR, AKT, and GSK-3β were found involved. In the end, ERRFI1 was proven to inhibit expression levels of CDK1, CDK2, cyclin B1, and cyclin D1, resulting an increased G2/M cell ratio. Overexpression of CK13 enhances the radiosensitivity of NPC cells, which is characterized by decreased cell viability and proliferation and increased apoptosis. This regulation may affect the survival of HNE-3 cells by increasing the expression of ERRFI1 and activating the EGFR/Akt/GSK-3β signaling pathway, providing new potential therapeutic targets for the treatment of NPC.

Cytokeratin 13 (CK13) expression in cancer: a tissue microarray study on 10,439 tumors

Cytokeratin 13 (CK13) is a type I acidic low molecular weight cytokeratin, which is mainly expressed in urothelium and in the squamous epithelium of various sites of origin. Loss of CK13 has been implicated in the development and progression of squamous epithelial neoplasms. To comprehensively determine CK13 expression in normal and neoplastic tissues, a tissue microarray containing 10,439 samples from 131 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. CK13 immunostaining was detectable in 42 (32.1%) of the 131 tumor categories including 24 (18.3%) tumor types with at least one strongly positive case. The highest rate of positive staining was found in various urothelial neoplasms (52.1-92.3%) including Brenner tumor of the ovary (86.8%) and in squamous cell carcinomas from various sites of origin (39.1-77.6%), Warthin tumors of parotid glands (66.7%), adenosquamous carcinomas of the cervix (33.3%), thymomas (16.0%), and endometroid carcinomas of the ovary (15.3%). Twenty other epithelial or germ cell neoplasms showed - a usually weak - CK13 positivity in less than 15% of the cases. In bladder cancer, reduced CK13 expression was linked to high grade and advanced stage (p < 0.0001 each). In squamous cell carcinoma of the cervix, reduced CK13 immunostaining was related to high grade (p = 0.0295) and shortened recurrence-free (p = 0.0094) and overall survival (p = 0.0274). In a combined analysis of 1,151 squamous cell carcinomas from 11 different sites of origin, reduced CK13 staining was linked to high grade (p = 0.0050). Our data provide a comprehensive overview on CK13 expression in normal and neoplastic human tissues. CK13 expression predominates in urothelial neoplasms and in squamous cell carcinomas of different organs, and a loss of CK13 expression is associated with aggressive disease in these tumors.

Dynamic changes in protein concentrations of keratins in crop milk and related gene expression in pigeon crops during different incubation and chick rearing stages

1. The objective of this study was to examine the keratin composition of crop milk, the variation of epithelial thickness and keratin (K) gene expression in samples from young pigeon during incubation and chick rearing.2. Crop milk was collected from 1-, 3- and 5-day-old squab crops for keratin content analysis. Results showed that K4 accounted for the highest proportion of all detected keratins.3. In total, 42 pairs of adult pigeons were allocated to seven groups according to different stages to collect crop samples. Gene expression studies showed that the K3 gene expression was maximised at rearing Day 15 (15) and R1 in males and females, respectively. K6a gene level was the greatest at R15 in females, whereas it peaked at incubation Day 4 (I4) in males. The K12, K13, K23 and K80 gene levels were inhibited at the peak period of crop milk formation in comparison with I4. In females, K cochleal expression peaked at I10, whereas it was the greatest at R25 in males. K4 and K14 gene expression was the highest at I10 in females, while K4 and K14 were minimised at I17 and R7 in males, respectively. Gene expressions of K5, K8, K19 and K20 in males and K19 in females were maximised at R1. The K5, K20 and K75 gene levels in females peaked at R7. K75 and K8 expressions in males and females reached a maximum value at R25 and I17, respectively.4. The epithelial thickness of male and female crops reached their greatest levels at R1 and had the highest correlation with K19.5. These results emphasised the importance of keratinisation in crop milk formation, and different keratins probably play various roles during this period. The K19 was probably a marker for pigeon crop epithelium development. The sex of the parent pigeon affected keratin gene expression profiles.

Cytokeratin 10 (CK10) expression in cancer: A tissue microarray study on 11,021 tumors

Cytokeratin 10 (CK10) is a type I acidic low molecular weight cytokeratin which is mainly expressed in keratinizing squamous epithelium of the skin. Variable levels of CK10 protein have been described in squamous carcinomas of different sites and in some other epithelial neoplasms. To comprehensively determine the prevalence of CK10 expression in normal and neoplastic tissues, a tissue microarray containing 11,021 samples from 131 different tumor types and subtypes was analyzed by immunohistochemistry. CK10 immunostaining was detectable in 41 (31.3 %) of 131 tumor categories, including 18 (13.7 %) tumor types with at least one strongly positive case. The highest rate of positive staining was found in squamous cell carcinomas from various sites of origin (positive in 18.6 %-66.1 %) and in Warthin tumors of salivary glands (47.8 %), followed by various tumor entities known to potentially exhibit areas with squamous cell differentiation such as teratomas (33.3 %), basal cell carcinomas of the skin (14.3 %), adenosquamous carcinomas of the cervix (11.1 %), and several categories of urothelial neoplasms (3.1 %-16.8 %). In a combined analysis of 956 squamous cell carcinomas from 11 different sites of origin, reduced CK10 staining was linked to high grade (p < 0.0001) and advanced stage (p = 0.0015) but unrelated to HPV infection. However, CK10 staining was not statistically related to grade (p = 0.1509) and recurrence-free (p = 0.5247) or overall survival (p = 0.5082) in 176 cervical squamous cell carcinomas. In the urinary bladder, CK10 staining occurred more commonly in muscle-invasive (17.7 %) than in non-invasive urothelial carcinomas (4.0 %-6.0 %; p < 0.0001). In summary, our data corroborate a role of CK10 as a suitable marker for mature, keratinizing squamous cell differentiation in epithelial tissues. CK10 immunohistochemistry may thus be instrumental for a more objective evaluation of the clinical significance of focal squamous differentiation in cancer.

Cytokeratin 13 promotes radiotherapy sensitivity of nasopharyngeal carcinoma by downregulating the MEK/ERK pathway

BACKGROUND

Radiation therapy is the first treatment choice for nasopharyngeal carcinoma (NPC), while radiation resistance and recurrence have become the primary factors and are associated with poor prognosis in the clinical treatment of NPC patients. The purpose of the present study was to explore the sensitivity and molecular basis of cytokeratin 13 (CK13) that regulates NPC radiotherapy.

METHODS

HNE-3 or C666-1 cell line was used for overexpression and knockdown tests. Under radiotherapy conditions, CCK-8 assay, clone formation assay, and flow cytometry analyzed the effects of CK13 overexpression on cell proliferation, apoptosis, and cell cycle, respectively. In addition, Western blotting detected CK13-mediated downregulation of cell cycle-related genes. The mouse subcutaneous tumor-bearing experiment identified the effects of CK13 overexpression on the treatment of NPC in vivo. Further, Western blotting, CCK-8 assay, and flow cytometry investigated whether the CK13-mediated cell apoptosis involves the MEK/ERK signaling pathway.

RESULTS

Overexpression of CK13 significantly inhibited the survival of HNE-3 cells under radiotherapy in vitro and in vivo, and there was a substantial decrease in cyclin-dependent kinase 4 and 6 (CDK4/6) levels promoting the cell percentage number in the G2/M phase and, subsequently, the ratio of the apoptotic cells. In contrast, the knockdown of CK13 showed the opposite partial regulatory effect. Interestingly, CK13 overexpression also showed a reduction in the survival of C666-1 cells and an increased ratio of the apoptotic cells under radiotherapy treatment. Furthermore, higher levels of CK13 downregulated the MEK/ERK signaling pathway, resulting in decreased HNE-3 cell proliferation and increased apoptosis. However, ERK activators were able to rescue the process partially.

CONCLUSIONS

Together, these results showed that CK13 promoted the radiosensitivity of NPC cells by downregulating the MEK/ERK signaling pathway. Thus, targeting CK13 provided insights into the treatment of NPC radiotherapy.

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.

Combined loss of expression of involucrin and cytokeratin 13 is associated with poor prognosis in squamous cell carcinoma of mobile tongue

BACKGROUND

This study aimed to evaluate the prognostic significance of expression levels of involucrin (IVL), cytokeratin (CK)-10 and -13 at different intratumor sites (tumor center and invading area) of oral tongue squamous cell carcinoma (OTSCC).

METHODS

IVL, CK13 and CK10 expression levels were examined in a multicenter cohort of 146 OTSCCs using immunohistochemistry. External mRNA datasets were used for expression analysis and/or to validate survival associations.

RESULTS

External transcriptomic datasets showed downregulation of IVL and KRT13 in oral malignancies including OTSCC as compared to normal controls. The combined loss of IVL and CK13 expression at the invading core but not at the center core was significantly associated with poor differentiation and reduced 5-year overall survival. Multivariate Cox analysis confirmed the loss of CK13 and IVL expression to be an independent prognostic factor. Transcriptomic dataset corroborated immunohistochemistry results.

CONCLUSIONS

Combined expression levlels of IVL and CK13 might be useful as prognostic biomarkers in OTSCC.

ATF3 downmodulates its new targets IFI6 and IFI27 to suppress the growth and migration of tongue squamous cell carcinoma cells

Activating transcription factor 3 (ATF3) is a key transcription factor involved in regulating cellular stress responses, with different expression levels and functions in different tissues. ATF3 has also been shown to play crucial roles in regulating tumor development and progression, however its potential role in oral squamous cell carcinomas has not been fully explored. In this study, we examined biopsies of tongue squamous cell carcinomas (TSCCs) and found that the nuclear expression level of ATF3 correlated negatively with the differentiation status of TSCCs, which was validated by analysis of the ATGC database. By using gain- or loss- of function analyses of ATF3 in four different TSCC cell lines, we demonstrated that ATF3 negatively regulates the growth and migration of human TSCC cells in vitro. RNA-seq analysis identified two new downstream targets of ATF3, interferon alpha inducible proteins 6 (IFI6) and 27 (IFI27), which were upregulated in ATF3-deleted cells and were downregulated in ATF3-overexpressing cells. Chromatin immunoprecipitation assays showed that ATF3 binds the promoter regions of the IFI6 and IFI27 genes. Both IFI6 and IFI27 were highly expressed in TSCC biopsies and knockdown of either IFI6 or IFI27 in TSCC cells blocked the cell growth and migration induced by the deletion of ATF3. Conversely, overexpression of either IFI6 or IFI27 counteracted the inhibition of TSCC cell growth and migration induced by the overexpression of ATF3. Finally, an in vivo study in mice confirmed those in vitro findings. Our study suggests that ATF3 plays an anti-tumor function in TSCCs through the negative regulation of its downstream targets, IFI6 and IFI27.

Activating transcription factor 3 (ATF3), a stress response gene, has been shown to play either tumor promoting or tumor suppressing functions depending on the type of tumor cell and the stromal context. Here we discovered that ATF3 plays an anti-tumor role in tongue squamous cell carcinoma (TSCC) cells through the transcriptional suppression of its new downstream targets interferon alpha inducible proteins 6 (IFI6) and 27 (IFI27). This finding contributes to understanding how ATF3, a transcriptional repressor, can target specific downstream genes in different tumor cells to play anti-tumor or pro-tumor functions. A thorough understanding of ATF3 functions and its downstream signaling pathways provides a potential approach to develop new therapeutics for the treatment of tumors such as TSCCs.

Significance of Cytokeratin-1 Single-Nucleotide Polymorphism and Protein Level in Susceptibility to Vocal Leukoplakia and Laryngeal Squamous Cell Carcinoma

OBJECTIVE

To investigate the association between the cytokeratin (CK)-1 single-nucleotide polymorphism (SNP), the protein level of CK-1 and the risk of vocal leukoplakia and laryngeal squamous cell carcinoma (LSCC).

METHODS

In this case-control study, 155 patients with vocal leukoplakia, 323 patients with LSCC, and 266 healthy controls were genotyped for the CK-1 (SNP RS14024) gene using pyrosequencing. The protein expression level of CK-1 was analyzed in vocal leukoplakia, LSCC, and vocal polyp patients by immunohistochemistry (IHC).

RESULTS

Of the CK-1 RS14024 polymorphism, the heterozygote AG and homozygote GG genotype exhibited a significantly increased risk of LSCC (AG: OR = 2.16, p = 0.014; GG: OR = 2.15, p = 0.018) compared to normal controls. A higher protein expression level of CK-1 was detected in patients with LSCC compared to vocal leukoplakia and polyps (both p < 0.001), and a significant increasing trend of CK-1 protein expression level from mild-moderate dysplasia to moderate-severe dysplasia in vocal leukoplakia patients was also observed (p = 0.006).

CONCLUSIONS

This study demonstrates that the CK-1 SNP and high protein expression levels are associated with vocal leukoplakia and LSCC and promote the transformation from vocal leukoplakia to LSCC in a Chinese Han population.

Differentiated vulvar intraepithelial neoplasia (dVIN): the most helpful histological features and the utility of cytokeratins 13 and 17

Differentiated vulvar intraepithelial neoplasia (dVIN) is the precursor lesion of HPV-negative vulvar squamous cell carcinoma (VSCC). The histopathological diagnosis of dVIN can be challenging, as it often resembles vulvar non-neoplastic epithelial disorders (NNED), especially lichen sclerosus (LS). We aimed to establish the most specific and reproducible histological features of dVIN and assessed cytokeratin 13 (CK13) and cytokeratin 17 (CK17) immunohistochemistry as a diagnostic aid. Consecutive cases of dVIN (n = 180) and LS (n = 105) from the period 2010 to 2013 were reviewed using a checklist of histological features. Each feature was recorded as ‘present’ or ‘absent’ and statistical comparison (dVIN vs LS) was made. Interobserver agreement between two pairs of pathologists was assessed for a subset of cases of dVIN (n = 31) and LS and other NNED (n = 23). Immunohistochemistry with CK13, CK17, MIB1 and p53 was performed on dVIN, LS, and other NNED cases. Macronucleoli, features of disturbed maturation and angulated nuclei were significantly more common in dVIN than LS (p < 0.001). We found ‘substantial agreement’ for the diagnosis of dVIN (κ = 0.71). Macronucleoli and deep keratinisation had the highest agreement. In dVIN, the mean percentage of cells staining with CK13 was 15 and with CK17, this was 74. For LS, the mean percentage of cells staining with CK13 was 31, and with CK17, this was 41. By plotting receiver operating characteristic curves (ROC), an area under the curve (AUC) of 0.52 was obtained for CK13, and an AUC of 0.87 was obtained for CK17. The most helpful histological features for diagnosing dVIN were macronucleoli, features of disturbed maturation, and angulated nuclei. Increased CK17 expression may have promise for supporting dVIN diagnosis.

Keratin 13 expression reprograms bone and brain metastases of human prostate cancer cells

Lethal progression of prostate cancer metastasis can be improved by developing animal models that recapitulate the clinical conditions. We report here that cytokeratin 13 (KRT13), an intermediate filament protein, plays a directive role in prostate cancer bone, brain, and soft tissue metastases. KRT13 expression was elevated in bone, brain, and soft tissue metastatic prostate cancer cell lines and in primary and metastatic clinical prostate, lung, and breast cancer specimens. When KRT13 expression was determined at a single cell level in primary tumor tissues of 44 prostate cancer cases, KRT13 level predicted bone metastasis and the overall survival of prostate cancer patients. Genetically enforced KRT13 expression in human prostate cancer cell lines drove metastases toward mouse bone, brain and soft tissues through a RANKL-independent mechanism, as KRT13 altered the expression of genes associated with EMT, stemness, neuroendocrine/neuromimicry, osteomimicry, development, and extracellular matrices, but not receptor activator NF-κB ligand (RANKL) signaling networks in prostate cancer cells. Our results suggest new inhibitors targeting RANKL-independent pathways should be developed for the treatment of prostate cancer bone and soft tissue metastases.

Gene expression profiling signatures for the diagnosis and prevention of oral cavity carcinogenesis-genome-wide analysis using RNA-seq technology

We compared the changes in global gene expression between an early stage (the termination of the carcinogen treatment and prior to the appearance of frank tumors) and a late stage (frank squamous cell carcinoma (SCC)) of tongue carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in a mouse model of human oral cavity and esophageal squamous cell carcinoma. Gene ontology and pathway analyses show that increases in “cell cycle progression” and “degradation of basement membrane and ECM pathways” are early events during SCC carcinogenesis and that changes in these pathways are even greater in the actual tumors. Myc, NFκB complex (NFKB1/RELA), and FOS transcription networks are the major transcriptional networks induced in early stage tongue carcinogenesis. Decreases in metabolism pathways, such as in “tricarboxylic acid cycle” and “oxidative phosphorylation”, occurred only in the squamous cell carcinomas and not in the early stages of carcinogenesis. We detected increases in ALDH1A3, PTGS2, and KRT1 transcripts in both the early and late stages of carcinogenesis. The identification of the transcripts and pathways that change at an early stage of carcinogenesis provides potentially useful information for early diagnosis and for prevention strategies for human tongue squamous cell carcinomas.

A proteomic approach to compare saliva from individuals with and without oral leukoplakia

BACKGROUND

Oral leukoplakia is the most common potentially malignant disorder in the oral cavity and can precede carcinoma. This study aimed to identify possible oral leukoplakia salivary biomarkers.

METHODS

Unstimulated saliva was collected from participants and protein concentration was determined. Proteins were then precipitated with cold acetone and separated using 2DE over a pH range of 3-10. Spot demarcation and matching were performed and protein identification was done through MS analysis. Oral leukoplakia tissues were submitted to immunohistochemistry analysis for keratin 10 (CK10). A complementary analysis of oral leukoplakias that were not included previously was performed in addition.

RESULTS

226±10 spots were identified in oral leukoplakia 2DE gels, and 262±12 spots were identified in volunteers. Twenty-two spots were highly abundant in oral leukoplakias or not detected in the control group, such as apolipoprotein A1, alpha amylase, cystatins, keratin 10, and lysozyme precursor. All were identified. All oral leukoplakia cases were immunopositive for CK10, mainly in the superficial epithelial layers.

CONCLUSIONS

The 2DE salivary protein profiles of individuals with and without oral leukoplakia were observably different. CK10 appears to be an interesting protein and should be further studied in oral carcinogenesis.

SIGNIFICANCE

MS-based proteomics enables large-scale analysis of proteins. Proteomics can provide detailed descriptions of proteomes of cells and tissues, including body fluids, and appears as a powerful tool to study human disorders. Saliva is readily accessible through non invasive collection and can mirror diverse disease states. Saliva from both diseased and healthy subjects can be analyzed through 2DE and differences between groups could be found. Routine immunohistochemistry analysis confirmed one of these findings, with CK10 being positive tissues from individuals with oral leukoplakia. Therefore, the present study allows insights into development of an important potential oral cancer precursor, named oral leukoplakia. However, the results can be extrapolated and tested in other precancer states, such as proliferative verrucous leukoplakia, patients at risk of oral cancer due to lifestyle behavior and/or cancer history in the family or even those who are under surveillance after a treated primary oral cancer.

Brush biopsy of human oral mucosal epithelial cells as a quality control of the cell source for fabrication of transplantable epithelial cell sheets for regenerative medicine

Autologous oral mucosal epithelial cell sheets have been used for treating epithelial defects such as cornea and esophagus. The cell source of patients' oral mucosal epithelial cell sheet should be examined in normality because it has individual difference. In this study, oral mucosal epithelial cells were less invasively collected by brush biopsy from the buccal, gingival, labial, and palate mucosa of four healthy volunteer donors without anesthesia, and analyzed the keratin expressions by western blotting and the obtained results were compared with those by immunohistochemistry of each of the native tissues. All of the oral mucosal epithelial cells expressed keratin 4 (K4) and K13, which were mucosal stratified squamous epithelial cell markers. K1 and K10, keratinized epithelial cell markers, were also detected in keratinized tissues such as gingival and palate mucosa. The markers of epithelial basal cells such as p63 and K15 were not detected by brush biopsy-western blotting. Although this method does not include basal layers of oral mucosa, protein expressions of upper layer of lesion area are different from normal. Therefore, brush biopsy-western blotting was extremely less invasive and would contribute to quality control of the fabrication of autologous oral mucosal epithelial cell sheets.

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Cell sheet source of patient oral mucosal condition has individual difference.

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A new less invasive method for quality check of human oral mucosal epithelial cells.

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Keratin expressions were examined by brush biopsy western blot.

Differential expression of stem cell-like proteins in normal, hyperplastic and dysplastic oral epithelium

Objective

The identification of stem cells (SC) remains challenging. In the human oral mucosal epithelium, these cells are believed to be in the basal layer (stem cell niche), but their exact location is unclear. The aim of this study was to examine the dysplastic oral epithelium for these SC-like proteins in order to assess their diagnostic value as biomarkers complementing the histological grading of dysplasia.

Material and Methods

Thirty oral epithelial dysplasia (OED), 25 oral lichen planus (OLP), 10 oral hyperkeratosis and 5 normal oral epithelium (OE) were immunohistochemically examined for four SC markers [integrin β1, neuron-glial-2 (NG2), notch 1 (N1) and keratin 15 (K15)].

Results

Three of four SC markers were heterogeneously detected in all samples. K15 overexpression in the lower two-thirds of severe OED suggests an expanded SC niche. Integrin β1 distribution pattern was not measurably different between OEDs and control. NG2 was almost negative to absent in all samples examined. N1 expression was weak and highly variable in normal and dysplastic epithelium, making it an unreliable epithelial stem cell marker.

Conclusions

Present findings suggest that these markers were unable to identify individual epithelial stem cells. Instead, subpopulations of cells, most probably stem cells and transit amplifying cells with stem cell-like properties were identified in the dysplastic oral epithelium. The characteristic expressions of K15 might be of diagnostic value for oral dysplasia and should be investigated further.

The Characteristics and Function of S100A7 Induction in Squamous Cell Carcinoma: Heterogeneity, Promotion of Cell Proliferation and Suppression of Differentiation

S100A7 is highly expressed in squamous cell carcinomas (SCC) and is related to the terminal differentiation of keratinocytes. However, its characteristic and function in SCC is not very known. In this present study, we used immunohistochemistry to examine the expression of S100A7 in 452 SCC specimens, including the lung, esophagus, oral cavity, skin, cervix, bladder, and three SCC cell lines. We found that S100A7-positive staining showed significant heterogeneity in six types of SCC specimen and three SCC cell lines. Further examination found that S100A7-positive cells and its expression at mRNA and protein levels could be induced in HCC94, FaDu, and A-431 cells both in vitro and in vivo using immunohistochemistry, real-time PCR, and Western blotting. Notably, the upregulation of squamous differentiation markers, including keratin-4, keratin-13, TG-1, and involucrin, also accompanied S100A7 induction, and a similar staining pattern of S100A7 and keratin-13 was found in HCC94 cells both in vitro and in vivo. Further study revealed that the overexpression of S100A7 significantly increased proliferation and inhibited squamous differentiation in A-431 cells both in vitro and in vivo. Conversely, silencing S100A7 inhibited cell growth and survival and increased the expression of keratin-4, keratin-13, TG-1, and involucrin in HCC94 cells. Therefore, these results demonstrate that S100A7 displays heterogeneous and inducible characteristic in SCC and also provide novel evidence that S100A7 acts as a dual regulator in promoting proliferation and suppressing squamous differentiation of SCC.

Connecting cyto-nano-architectural attributes and epithelial molecular expression in oral submucous fibrosis progression to cancer

OBJECTIVE

Problems in pre-cancer diagnosis complicate cancer theragnosis as well as life expectancy. There is uncertainty regarding malignant transformation of oral submucous fibrosis (OSF), an oral pre-cancer with dysplastic (OSFWD) and non-dysplastic (OSFWT) subtypes. Understanding the structural, molecular and physical aspects of epithelial homeostasis may be useful.

MATERIALS AND METHODS

Histopathological grading of biopsy sections was performed using H&E staining. Alterations in epithelial surface architecture in different groups was evaluated using scanning electron microscopy (SEM). The expression of crucial epithelial genes (p63, CK-5/6, CK-10, E-cadherin and β-catenin) was studied by immunohistochemistry, Western blot and RT-PCR analysis.

RESULTS

SEM observations revealed that the surface epithelial ridge pattern became thick and dense, and pit pattern gradually decreased in OSFWD and oral squamous cell carcinoma (OSCC). p63, ΔNp63 and CK-5/6 were up-regulated in OSFWD and OSCC but down-regulated in OSFWT. CK-10 was down-regulated in OSFWD compared to OSFWT. Cytoplasmic expression of E-cadherin and β-catenin was elevated in dysplastic and cancerous conditions. Moreover, statistical correlation between SEM features (ridges and pits) and molecular attributes demonstrated a significant positive relationship between the ridge-to-pit ratio and p63 population density (r=0.85) and the ridge-to-pit ratio and CK-5/6 intensity (r=0.63).

CONCLUSIONS

Molecular changes related to epithelial progressive maturation and cellular proliferation are correlated with concomitant alteration of epithelial surface architecture which helps to predict the malignant potentiality of OSF.

Oral-specific ablation of Klf4 disrupts epithelial terminal differentiation and increases premalignant lesions and carcinomas upon chemical carcinogenesis

BACKGROUND

Squamous cell carcinoma (SSC) of the head and neck is the sixth most common cancer and is rarely diagnosed in early stages. The transcription factor Krϋppel-like factor 4 (Klf4) suppresses cell proliferation and promotes differentiation. Inducible mice carrying an oral-specific ablation of Klf4 (K14-CreER(tam) /Klf4(flox/flox) ) develop mild dysplastic lesions and abnormal differentiation in the tongue. Aiming to analyze whether Klf4 cooperate in oral chemical carcinogenesis,we applied 4-nitroquinoline 1-oxide (4NQO), a tobacco surrogate, to this conditional Klf4 knockout mice.

METHODS

K14-CreER(tam) /Klf4(flox/flox) and control mice were treated with 4NQO for 16 weeks and monitored until week 30. Histopathological samples were used for diagnostic purposes and immunofluorescence detection of epithelial differentiation markers.

RESULTS

4NQO-treated K14-CreER(tam) /Klf4(flox/flox) mice (Klf4KO 4NQO) showed a significant weight loss and developed more severe dysplastic lesions than control mice with 4NQO (P < 0.005). The Klf4KO 4NQO showed a tendency to higher incidence of oral SCC and a marked keratinization pattern in dysplasias, in situ carcinomas and SCC. Also, tongues derived from Klf4KO 4NQO mice exhibited reduced terminal differentiation as judged by cytokeratin 1 staining when compared with 4NQO-treated controls.

CONCLUSIONS

Klf4 ablation results in more severe dysplastic lesions in oral mucosa, with a tendency to higher incidence of SCC, after chemical carcinogenesis. We show here, in a context similar to the human carcinogenesis, that absence of Klf4 accelerates carcinogenesis and correlates with the absence of cytokeratin 1 expression. These results suggest a potential role for KLF4 as a tumor suppressor gene for the tongue epithelium.

Evaluation of superficial oral squamous cell malignancy based on morphometry and immunoexpression of cytokeratin 13 and cytokeratin 17

OBJECTIVE

Evaluation of combined morphometry and immunoexpression of cytokeratin 13 (CK13) and cytokeratin 17 (CK17) for cytological identification of superficial oral squamous cells.

STUDY DESIGN

Smears from 11 tongue squamous cell carcinoma patients were processed by liquid-based cytology, stained via the Papanicolaou method and divided into multiple specimens by cell transfer. Morphometric indices, including nuclear area, nuclear perimeter, nuclear circular rate, largest-to-smallest dimension ratio of the nucleus and nucleocytoplasmic ratio, were measured using a computerized analysis system. CK13 and CK17 were detected by immunostaining. Morphometric values were compared between cell populations with distinct staining and immunoexpression patterns.

RESULTS

Most orange G-stained superficial cells were negative for CK13 (99.4%) and CK17 (98.6%). For light green-stained superficial cells, loss of CK13 was associated with greater cellular atypia in the nuclear area, nuclear perimeter and nucleocytoplasmic ratio (p < 0.01), while expression of CK17 was related to higher-grade cellular atypia in the same parameters (p < 0.01) as well as the nuclear circular rate (p < 0.05).

CONCLUSION

Immunoexpression of CK13 and CK17 in light green-stained superficial cells was associated with more severe morphological atypia. Combined morphometry and immunoexpression of CK13 and CK17 might be useful for cytological diagnosis of this cell population.

Gene expression profiling for the purposes of biomarker discovery in oral potentially malignant lesions: a systematic review

Early and accurate diagnosis of oral potentially malignant lesions (OPML) is of critical importance in preventing malignant transformation. Although histopathological interpretation of the degree of epithelial dysplasia is considered the gold standard for diagnosis, this method is subjective and lacks sensitivity. Therefore, many attempts have been made to identify objective molecular biomarkers to improve diagnosis. Microarray technology has the advantage of screening the expression of the whole genome making it one of the best tools for searching for novel biomarkers. However, microarray studies of OPMLs are limited, and no review has been published to highlight and compare their findings. In this paper, we systematically review all studies that have incorporated microarray analyses in the investigation of gene profile alterations in OPMLs and suggest a set of commonly dysregulated genes across multiple gene expression profile studies. This list of common genes may help focus selection of markers for further analysis regarding their importance in the diagnosis and prognosis of OPMLs.

Can immunohistochemistry serve as an alternative to subjective histopathological diagnosis of oral epithelial dysplasia?

Many attempts have been made to identify objective molecular biomarkers to diagnose and prognosticate oral epithelial dysplasia (OED) because histopathological interpretation is subjective and lacks sensitivity. The majority of these efforts describe changes in gene expression at protein level in OED as determined by immunohistochemistry (IHC). However, the literature on these putative markers of oral cancer progression is vast and varied. The main purpose of this article is to review current knowledge on biomarkers of protein expression for OED by IHC approaches. We further discuss these findings in terms of the proposed essential hallmarks of cancer cells to better understand their role in oral oncogenesis.

Downregulation of keratin 76 expression during oral carcinogenesis of human, hamster and mouse

Background

Keratins are structural marker proteins with tissue specific expression; however, recent reports indicate their involvement in cancer progression. Previous study from our lab revealed deregulation of many genes related to structural molecular integrity including KRT76. Here we evaluate the role of KRT76 downregulation in oral precancer and cancer development.

Methods

We evaluated KRT76 expression by qRT-PCR in normal and tumor tissues of the oral cavity. We also analyzed K76 expression by immunohistochemistry in normal, oral precancerous lesion (OPL), oral squamous cell carcinoma (OSCC) and in hamster model of oral carcinogenesis. Further, functional implication of KRT76 loss was confirmed using KRT76-knockout (KO) mice.

Results

We observed a strong association of reduced K76 expression with increased risk of OPL and OSCC development. The buccal epithelium of DMBA treated hamsters showed a similar trend. Oral cavity of KRT76-KO mice showed preneoplastic changes in the gingivobuccal epithelium while no pathological changes were observed in KRT76 negative tissues such as tongue.

Conclusion

The present study demonstrates loss of KRT76 in oral carcinogenesis. The KRT76-KO mice data underlines the potential of KRT76 being an early event although this loss is not sufficient to drive the development of oral cancers. Thus, future studies to investigate the contributing role of KRT76 in light of other tumor driving events are warranted.

Architectural characterization of organotypic cultures of H400 and primary rat keratinocytes

Organotypic epithelial structures can be cultured using primary or immortalized keratinocytes. However, there has been little detailed quantitative histological characterization of such cultures in comparison with normal mucosal architecture. The aim of this study is to identify morphological markers of tissue architecture that can be used to monitor tissue structure, maturation, and differentiation and to enable quantitative comparison of organotypic cultures (OCs) with normal oral mucosa. OCs of oral keratinocytes [immortalized H400 or primary rat keratinocytes (PRKs)] were generated using the three scaffolds of de-epidermalized dermis (DED), polyethylene terephthalate (PET), and collagen gels for up to 14 days. Cultures and normal epithelium were analyzed immunohistochemically and by using the semi-quantitative reverse transcriptase polymerase chain reaction (sq-RT-PCR) for E-cadherin, desmoglein-3, plakophilin, involucrin, cytokeratins-1, -5, -6, -10, -13, and Ki67. The epithelial thickness of OCs was measured in stained sections using image processing. Histological analysis revealed that air-liquid interface (ALI) cultures generated stratified organotypic epithelial structures by 14-days. The final thickness of these cultures as well as the degree of maturation/stratification (including stratum corneum formation) varied significantly depending on the scaffold used. For certain scaffolds, the immunohistochemical profiles obtained recapitulated those of normal oral epithelium indicating comparable in vitro differentiation and proliferation. In conclusion, quantitative microscopy approaches enabled unbiased architectural characterization of OCs. The scaffold materials used in the present study (DED, collagen type-I and PET) differentially influenced cell behavior in OCs of oral epithelia. H400 and PRK OCs on DED at the ALI demonstrated similar characteristics in terms of gene expression and protein distribution to the normal tissue architecture.

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.

Morphological evaluation of tongue mucosa in burning mouth syndrome

OBJECTIVE

The aim of the present study was to perform a morphological evaluation by immunofluorescence of biomarkers of keratinocyte intercellular adhesion, and of differentiation in the tongue mucosa of burning mouth syndrome patients (BMS), compared with a control group.

DESIGN

A prospective blinded evaluation of tongue mucosal specimens processed for light microscopy was performed. Intercellular adhesion was evaluated by investigating the expression of desmoglein 1, desmoglein 3, and of occludin. Keratin 10 and keratin 14 (markers of epithelial differentiation) were also evaluated, as keratin 16 (marker for activated keratinocytes after epithelial injury). Apoptotic cascade was investigated by p53 and activated caspase-3 expression. The basal membrane integrity was analysed through laminin immunoreactivity.

RESULTS

In both groups, a preserved three-dimensional architecture of the tongue was observed. Desmoglein 1 and desmoglein 3 epithelial distributions were similar in the desmosomes of patients and control subjects. Again, keratin 10 immunoreactivity and distribution pattern of keratin 14 in the epithelial compartment was similar in both groups. In control samples, keratin 16 immunoreactivity was scant throughout the epithelium with a punctuate and scattered cytoplasmic labelling. In contrast, in all BMS patients keratinocyte cytoplasm was homogeneously labelled for keratin 16, with a more intense staining than controls. Furthermore, keratin 16 staining progressively decreased proceeding towards the most superficial epithelial layers.

CONCLUSIONS

The results of this study are consistent with and support the clinically normal features of oral mucosa in BMS, and suggest that keratin 16 may be involved in the cell mechanisms underlying the syndrome occurrence.

Emergence of keratin 17 vs. loss of keratin 13: their reciprocal immunohistochemical profiles in oral carcinoma in situ

To evaluate differential expressions for keratin (K) subtypes 13 and 17 in oral borderline malignancies, we examined 67 surgical specimens of the oral mucosa for their immunohistochemical profiles. From those specimens, 173 foci of epithelial dysplasia, 152 foci of carcinoma in situ (CIS), and 82 foci of squamous cell carcinoma (SCC) were selected according to our diagnostic criteria, along with 20 areas of normal epithelia. In normal epithelia, there was no K17 positivity (0%), whereas definite K13 positivity (100%) was observed. The same tendencies were obtained in mild (undefined) and moderate (true) epithelial dysplasias (K17: 0%; K13: 100%). In contrast, all CIS (100%) had K17 positivities, while K13 positivities were lost in many of them (7%). Similar tendencies were confirmed in invasive SCC (K17: 100%, K13: 4%). Simultaneous immunopositivities for K17 and K13 were found only in SCC (7%) and CIS (4%) foci with distinct keratinization. These foci also showed K10 positivities, though K10 positive areas were not identical to K13 positive areas. The results indicate that expressions of K17 and K13 are reciprocal in oral epithelial lesions and that the K17 emergence is related to malignancies.

Acute sensitivity of the oral mucosa to oncogenic K-ras

Mouse models of cancer represent powerful tools for analysing the role of genetic alterations in carcinogenesis. Using a mouse model that allows tamoxifen-inducible somatic activation (by Cre-mediated recombination) of oncogenic K-ras^G12D in a wide range of tissues, we observed hyperplasia of squamous epithelium located in moist or frequently abraded mucosa, with the most dramatic effects in the oral mucosa. This epithelium showed a sequence of squamous hyperplasia followed by squamous papilloma with dysplasia, in which some areas progressed to early invasive squamous cell carcinoma, within 14 days of widespread oncogenic K-ras activation. The marked proliferative response of the oral mucosa to K-ras^G12D was most evident in the basal layers of the squamous epithelium of the outer lip with hair follicles and wet mucosal surface, with these cells staining positively for pAKT and cyclin D1, showing Ras/AKT pathway activation and increased proliferation with Ki-67 and EdU positivity. The stromal cells also showed gene activation by recombination and immunopositivity for pERK indicating K-Ras/ERK pathway activation, but without Ki-67 positivity or increase in stromal proliferation. The oral neoplasms showed changes in the expression pattern of cytokeratins (CK6 and CK13), similar to those observed in human oral tumours. Sporadic activation of the K-ras^G12D allele (due to background spontaneous recombination in occasional cells) resulted in the development of benign oral squamous papillomas only showing a mild degree of dysplasia with no invasion. In summary, we show that oral mucosa is acutely sensitive to oncogenic K-ras, as widespread expression of activated K-ras in the murine oral mucosal squamous epithelium and underlying stroma can drive the oral squamous papilloma–carcinoma sequence. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Oral premalignant lesions: from the pathological viewpoint

Under the widely used World Health Organization (WHO) classification for the pathological diagnosis of oral premalignant lesions, dysplasia, which is graded as mild, moderate or severe, and carcinoma in situ (CIS), which is a non-invasive carcinoma, are classified as precursor lesions of oral squamous cell carcinoma. Since the first edition (Wahi et al. International histological classification of tumours no. 4, WHO, Geneva, 1971), the criterion for CIS--that all epithelial layers are replaced by atypical cells--has remained unchanged. However, this dysplasia-carcinoma sequence theory was introduced from the viewpoint of pathological changes in the uterine cervix: in contrast, almost all premalignant lesions and CIS of the oral mucosa show superficial maturation and differentiation. Based on this recognition, the squamous intraepithelial neoplasia (SIN) classification and Ljubljana classification were included in WHO's latest edition published in 2005. Although the WHO classification is commonly used in Japan, recent developments in oral oncology have promoted modifications of the classification used in this country. In 2005, the Working Group of the Japan Society for Oral Tumours advocated iodine staining and proposed a modified SIN system, and in 2007, the Working Committee of the Japanese Society for Oral Pathology (JSOP) reported a new CIS (JSOP) definition that included differentiated-type CIS. In 2010, based on these studies, a new entity--oral intraepithelial neoplasia (OIN)--was included in the first edition of General Rules for Clinical and Pathological Studies on Oral Cancer. In this review, we focus on the OIN/CIS (JSOP) new classification of premalignant lesions in oral mucosa, which further advances the concept of SIN.

An in vitro three-dimensional model of primary human cutaneous squamous cell carcinoma

Squamous cell carcinomas (SCC) represent a substantial clinical problem because of increases, frequent recurrences and successive de novo tumors, especially in organ transplant recipients. To improve upon the current surgical and other non-selective therapies, a validated organotypic in vitro model of primary human SCC needs to be developed. Such a model will have obvious advantages over current cell line and animal based approaches, and may render the latter partly obsolete. In a first approach, an explant technique of primary SCC biopsies onto dermal constructs was used to emulate tumor expansion in an in vitro model. Histological analysis revealed the formation of nests of squamous cells, mimicking an invasive morphological feature of primary SCC. Immunohistochemical analysis comprised an array of markers characteristic of keratinocyte (hyper) proliferation (K6, K16, K17 and Ki67), differentiation (K1, K10 and involucrin), basement membrane (collagen types IV and VII, integrins alpha(6) and beta(4) and laminin 332) and SCC (K4, K13 and Axl). The generated human SCC models displayed disturbed differentiation and keratins associated with hyperproliferation, but a low frequency of Ki67 positive cells. Basement membrane composition of the in vitro SCC model resembled that of normal skin. These results show for the first time that in vitro modelling of three-dimensional growth of primary cutaneous human SCC is feasible. This model may provide a platform to develop refined preventive and curative treatments and thereby gain understanding of SCC pathogenesis.

C-reactive protein: vascular risk marker in elderly patients with mental illness

BACKGROUND

There is increasing evidence that vascular disease contributes to cognitive impairment and dementia. Clarification of the role of vascular risk factors in dementia is important because most are modifiable, in contrast to other risk factors such as age and genetics.

METHODS

In 428 patients with mental illness we have investigated the relation of vascular disease to diagnoses, and a biochemical parameter, C-reactive protein (CRP), which is associated with inflammation and vascular disease.

RESULTS

Patients with vascular disease showed higher CRP levels than patients without vascular disease. Furthermore, patients with Alzheimer's disease showed lower CRP levels than patients with vascular dementia, mild cognitive impairment or depression. There is no obvious reason for this finding, since it could not be attributed to drug treatment.

CONCLUSION

The findings indicate that the control of conventional vascular risk factors and therapy could be guided by the level of CRP.

1H NMR-based metabonomic and pattern recognition analysis for detection of oral squamous cell carcinoma

BACKGROUND

Metabonomic analysis has been increasingly used to monitor metabolic abnormalities in cells and their microenvironment in order to detect the cancer markers recently. We evaluated the feasibility of applying (1)H nuclear magnetic resonance ((1)H NMR) based metabonomic method in the early detection of the differences in the plasma from 3 groups, which were patients with oral squamous cell carcinoma (OSCC), patients with oral leukoplakia (OLK), and the healthy control group.

METHODS

(1)H NMR spectra were obtained from human plasma samples prior to spectral analysis. The obtained data were processed by both the unsupervised principal component analysis (PCA) and the supervised partial least squares discriminant analysis (PLS-DA) to find out the differences among the three groups.

RESULTS

PLS-DA analysis has revealed a good model to detect the NMR data that can differentiate the OSCC patients from the OLK patients and the controls using a test set.

CONCLUSION

The results indicated that the (1)H NMR-based metabonomic approach is a feasible and efficient method for differentiating the OSCC patient's plasma from the healthy controls. As a potential novel strategy and a more convenient technique, it deserves a further evaluation for an early detection of oral cancer.

Gene expression signatures that can discriminate oral leukoplakia subtypes and squamous cell carcinoma

The purpose of this study is to generate a classifier for oral squamous cell carcinoma (OSCC) and leukoplakias (LPs), and evaluate its diagnostic potential. In order to identify marker gene candidates, differential gene expression between LPs and OSCCs were examined by cDNA microarray. The expression of 118 marker gene candidates was further evaluated by quantitative reverse transcription-PCR (QRT-PCR) analyses of 27 OSCC and 19 LP tissues. We identified 12 up-regulated and 15 down-regulated marker genes in OSCCs compared to LPs. Using Fisher's linear discriminant analysis (LDA), we demonstrated that 11-gene predictors among this novel marker set could best distinguish OSCCs from LPs (>97% accuracy), whereas a further seven of these gene predictors could be utilized to distinguish higher grade (higher than moderate) from lower grade (lower than mild) dysplasias (>95% accuracy). These predictor gene sets provide multigene classifiers for the diagnosis of pre-cancerous to cancerous transition of oral malignancy.

KLF6 allelic loss is associated with tumor recurrence and markedly decreased survival in head and neck squamous cell carcinoma

The Krüppel-like transcription factor (KLF6) gene is a tumor suppressor gene (TSG) reported to be dysregulated and inactivated through loss of heterozygosity (LOH) and/or somatic mutation in a number of major human cancers. The aim of the present study was to examine KLF6 gene status and expression in head and neck squamous cell carcinomas (HNSCC). A collection of 81 well-characterized oral and oropharyngeal HNSCC samples were analyzed for evidence of KLF6 LOH and mutation and differences in expression patterns between normal and cancerous tissues and these findings were correlated with clinicopathological variables. We also tested the effect of KLF6 inhibition in HNSCC cell lines on proliferation and p21 expression. LOH was found in approximately 30% of cases and was strongly correlated with cancer progression, tumor recurrence and decreased patient survival. Overall, median survival of patients with LOH was less than half (19 vs. 41 months, p=0.036, stratified on stage) than those without loss. Risk of death for patients with LOH was 8 times greater independent of tumor size, nodal status, tobacco smoking or treatment modality (HR 7.89, 95% CI: 1.9-32.4). Subsequent analyses revealed KLF6 mutations in only 2 of 20 samples, but altered subcellular protein localization in 64% of tumors. Targeted stable reduction of KLF6 in HNSCC cell lines increased cellular proliferation while decreasing p21 expression. Taken together, these findings suggest that KLF6 LOH represents a clinically-relevant biomarker predicting patient survival and tumor recurrence and that dysregulation of KLF6 function plays an important role in HNSCC progression.

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.

Inducible activation of oncogenic K-ras results in tumor formation in the oral cavity

Mouse models for cancer represent powerful tools to analyze the causal role of genetic alterations in cancer development. We have developed a novel mouse model that allows the focal activation of mutations in stratified epithelia. Using this system, we demonstrate that activation of an oncogenic K-rasG12D allele in the oral cavity of the mouse induces oral tumor formation. The lesions that develop in these mice are classified as benign squamous papillomas. Interestingly, these tumors exhibit changes in the expression pattern of keratins similar to those observed in human premalignant oral tumors, which are reflective of early stages of tumorigenesis. These results demonstrate a causal role for oncogenic K-ras in oral tumor development. The inducible nature of this model also makes it an ideal system to study cooperative interactions between mutations in oncogenes and/or tumor suppressor genes that are similar to those observed in human tumors. To our knowledge, this is the first reported inducible mouse model for oral cancer.