Cytokeratin and vimentin expression in normal epithelium and benign lesions of the vocal cords

Utility of CK8, CK10, CK13, and CK17 in Differential Diagnostics of Benign Lesions, Laryngeal Dysplasia, and Laryngeal Squamous Cell Carcinoma

There are no reliable immunohistochemical markers for diagnosing laryngeal squamous cell carcinoma (SCC) or diagnosing and grading laryngeal dysplasia. We aimed to evaluate the diagnostic utility of CK8, CK10, CK13, and CK17 in benign laryngeal lesions, laryngeal dysplasia, and laryngeal SCC. This retrospective study included 151 patients diagnosed with laryngeal papilloma, laryngeal polyps, laryngeal dysplasia, and laryngeal SCC who underwent surgical treatment between 2010 and 2020. Immunohistochemistry (IHC) was carried out using specific monoclonal antibodies against CK8, CK10, CK13, and CK17. Two experienced pathologists performed semi-quantitative scoring of IHC positivity. The diagnostic significance of the markers was analyzed. CK13 showed a sensitivity of 100% and a specificity of 82.5% for distinguishing between laryngeal SCC and laryngeal dysplasia and benign lesions. CK17 showed a sensitivity of 78.3% and specificity of 57.1% for the detection of laryngeal SCC vs. laryngeal dysplasia. CK10 showed a sensitivity of 80.0% for discriminating between low-grade and high-grade dysplasia, and a specificity of 61.1%. Loss of CK13 expression is a reliable diagnostic tool for diagnosing laryngeal lesions with malignant potential and determining resection lines. In lesions with diminished CK13 expression, CK17 could be used as an auxiliary immunohistochemical marker in diagnosing laryngeal SCC. In CK13-negative and CK17-positive lesions, CK10 positivity could be used to determine low-grade dysplasia. CK8 is not a useful IHC marker in differentiating between benign laryngeal lesions, laryngeal dysplasia, and laryngeal SCC.

High-resolution magnetic resonance and mass spectrometry imaging of the human larynx

High-resolution, noninvasive and nondestructive imaging of the subepithelial structures of the larynx would enhance microanatomic tissue assessment and clinical decision making; similarly, in situ molecular profiling of laryngeal tissue would enhance biomarker discovery and pathology readout. Towards these goals, we assessed the capabilities of high-resolution magnetic resonance imaging (MRI) and matrix-assisted laser desorption/ionisation-mass spectrometry (MALDI-MS) imaging of rarely reported paediatric and adult cadaveric larynges that contained pathologies. The donors were a 13-month-old male, a 10-year-old female with an infraglottic mucus retention cyst and a 74-year-old female with advanced polypoid degeneration and a mucus retention cyst. MR and molecular imaging data were corroborated using whole-organ histology. Our MR protocols imaged the larynges at 45-117 μm² in-plane resolution and capably resolved microanatomic structures that have not been previously reported radiographically-such as the vocal fold superficial lamina propria, vocal ligament and macula flavae; age-related tissue features-such as intramuscular fat deposition and cartilage ossification; and the lesions. Diffusion tensor imaging characterised differences in water diffusivity, primary tissue fibre orientation, and fractional anisotropy between the intrinsic laryngeal muscles, mucosae and lesions. MALDI-MS imaging revealed peptide signatures and putative protein assignments for the polypoid degeneration lesion and the N-glycan constituents of one mucus retention cyst. These imaging approaches have immediate application in experimental research and, with ongoing technology development, potential for future clinical application.

RNA Sequencing Reveals Cancer-Associated Changes in Laryngeal Cells Exposed to Non-Acid Pepsin

OBJECTIVE

Laryngopharyngeal reflux (LPR) is a common affliction that contributes to laryngeal inflammation, symptoms that impact quality of life, and life-threatening illnesses such as cancer. Effective treatment strategies for LPR are lacking. Pepsin is a proinflammatory and carcinogenic element of refluxate. Investigation of molecular pathways involved in pepsin-mediated damage may lead to identification of novel biomarkers and therapeutic targets for LPR. In this study, RNA sequencing was used to examine changes in human laryngeal epithelial cells following brief pepsin insult. Cells were immortalized to generate a model to aid future study of laryngeal injury and therapeutics.

STUDY DESIGN

In vitro translational.

METHODS

Laryngeal epithelial cells were cultured from a patient without signs or symptoms of LPR or laryngeal cancer. Cells were treated with 0.1 mg/ml pepsin for 1 hour or normal growth media (control) prior to RNA sequencing. Cells were immortalized via HPV E6/7 and characterized by microscopy, immunohistochemistry, G-banding, and soft agar assay.

RESULTS

Three hundred ninety-seven genes exhibited differences in expression with pepsin treatment (P < .05). Pathway analysis revealed association with cancer and related signaling processes including dysregulation of cancer-associated molecules, Metastasis-Associated Lung Adenocarcinoma Transcript 1 and KRT82, and the long-noncoding RNA, lipoprotein receptor-related protein 1 (LRP1)-AS, which regulates the putative pepsin receptor LRP1.

CONCLUSIONS

A single, brief exposure to pepsin activated cancer-associated signaling pathways in laryngeal cells in vitro, revealing novel mechanisms by which chronic reflux may contribute to carcinogenesis. The cell line developed herein represents a novel tool in which to investigate pepsin-dysregulated pathways identified by RNA sequencing and disparities of tumor proneness of laryngeal subsites.

LEVEL OF EVIDENCE

N/A Laryngoscope, 131:121-129, 2021.

Morphological and immunohistochemical identification of epithelial-to-mesenchymal transition in clinical prostate cancer

Epithelial-to-mesenchymal transition (EMT) is a process known to be associated with aggressive tumor behavior, metastasis and treatment resistance. It is characterized by coincidental upregulation of mesenchymal markers such as vimentin, fibronectin and N-cadherin concurrent with E-cadherin downregulation. Studies on EMT are generally performed in cell lines and mouse models, while the histopathological and phenotypical properties in clinical prostate cancer (PCa) are still unclear.

The objective of this study was to identify EMT in PCa patients. We demonstrated that N-cadherin, vimentin and fibronectin were generally not co-expressed in corresponding tumor regions. Immunofluorescent double stainings confirmed that co-expression of mesenchymal markers was uncommon, as we found no prostate cancer cells that co-expressed N-cadherin with fibronectin and only rare (<1%) cells that co-expressed N-cadherin with vimentin. Downregulation of E-cadherin was demonstrated in all N-cadherin positive tumor cells, but not in vimentin or fibronectin positive tumor cells. We further analyzed N-cadherin expression in morphologically distinct PCa growth patterns in a radical prostatectomy cohort (n = 77) and found that N-cadherin is preferentially expressed in ill-defined Gleason grade 4 PCa. In conclusion, we demonstrate that N-cadherin is the most reliable marker for EMT in clinical PCa and is preferentially expressed in ill-defined Gleason grade 4 growth pattern.

Cytokeratin-17 as a Potential Marker for Squamous Cell Carcinoma of the Larynx

To assess cytokeratin-17 (CK17) as an immunohistochemical marker for squamous cell carcinoma of the larynx, we stained 63 tissue samples from 63 consecutive patients who were believed or suspected to have squamous cell carcinoma of the larynx for CK17 and analyzed them by computerized histomorphometry. The mean staining intensity for CK17 was significantly stronger (p < .01) in cancerous cells, dysplasia, and normal epithelium proximal to the tumor than in distal normal epithelium and polyps. The percentage of stained area, within samples taken from a single patient, was significantly higher in malignancy and dysplasia as compared to distal normal epithelium and in malignancy as compared to dysplasia and proximal normal epithelium (p < .001). The integrated optical density was significantly higher in the malignant epithelium, dysplasia, polyps, and proximal normal epithelium than in distal normal epithelium (p < .0001). We conclude that CK17 is a highly sensitive and specific immunohistochemical marker for premalignant and malignant transformation in the larynx. Further investigation is warranted in order to assess the role of CK17 in determining safe resection borders.

Identification of distinct layers within the stratified squamous epithelium of the adult human true vocal fold

OBJECTIVES/HYPOTHESIS

A precise molecular schema for classifying the different cell types of the normal human vocal fold epithelium is lacking. We hypothesize that the true vocal fold epithelium has a cellular architecture and organization similar to that of other stratified squamous epithelia including the skin, cornea, oral mucosa, and esophagus. In analogy to disorders of the skin and gastrointestinal tract, a molecular definition of the normal cell types within the human vocal fold epithelium and a description of their geometric relationships should serve as a foundation for characterizing cellular changes associated with metaplasia, dysplasia, and cancer.

STUDY DESIGN

Qualitative study with adult human larynges.

METHODS

Histologic sections of normal human laryngeal tissue were analyzed for morphology (hematoxylin and eosin) and immunohistochemical protein expression profile, including cytokeratins (CK13 and CK14), cornified envelope proteins (involucrin), basal cells (NGFR/p75), and proliferation markers (Ki67).

RESULTS

We demonstrated that three distinct cell strata with unique marker profiles are present within the stratified squamous epithelium of the true vocal fold. We used these definitions to establish that cell proliferation is restricted to certain cell types and layers within the epithelium. These distinct cell types are reproducible across five normal adult larynges.

CONCLUSION

We have established that three layers of cells are present within the normal adult stratified squamous epithelium of the true vocal fold. Furthermore, replicating cell populations are largely restricted to the parabasal strata within the epithelium. This delineation of distinct cell populations will facilitate future studies of vocal fold regeneration and cancer.

LEVEL OF EVIDENCE

N/A.

The CD44+ ALDH+ population of human keratinocytes is enriched for epidermal stem cells with long-term repopulating ability

Like for other somatic tissues, isolation of a pure population of stem cells has been a primary goal in epidermal biology. We isolated discrete populations of freshly obtained human neonatal keratinocytes (HNKs) using previously untested candidate stem cell markers aldehyde dehydrogenase (ALDH) and CD44 as well as the previously studied combination of integrin α6 and CD71. An in vivo transplantation assay combined with limiting dilution analysis was used to quantify enrichment for long-term repopulating cells in the isolated populations. The ALDH(+) CD44(+) population was enriched 12.6-fold for long-term repopulating epidermal stem cells (EpiSCs) and the integrin α6(hi) CD71(lo) population was enriched 5.6-fold, over unfractionated cells. In addition to long-term repopulation, CD44(+) ALDH(+) keratinocytes exhibited other stem cell properties. CD44(+) ALDH(+) keratinocytes had self-renewal ability, demonstrated by increased numbers of cells expressing nuclear Bmi-1, serial transplantation of CD44(+) ALDH(+) cells, and holoclone formation in vitro. CD44(+) ALDH(+) cells were multipotent, producing greater numbers of hair follicle-like structures than CD44(-) ALDH(-) cells. Furthermore, 58% ± 7% of CD44(+) ALDH(+) cells exhibited label-retention. In vitro, CD44(+) ALDH(+) cells showed enhanced colony formation, in both keratinocyte and embryonic stem cell growth media. In summary, the CD44(+) ALDH(+) population exhibits stem cell properties including long-term epidermal regeneration, multipotency, label retention, and holoclone formation. This study shows that it is possible to quantify the relative number of EpiSCs in human keratinocyte populations using long-term repopulation as a functional test of stem cell nature. Future studies will combine isolation strategies as dictated by the results of quantitative transplantation assays, in order to achieve a nearly pure population of EpiSCs.

Epidermal growth factor-induced modulation of cytokeratin expression levels influences the morphological phenotype of head and neck squamous cell carcinoma cells

The migratory ability of tumor cells requires cytoskeletal rearrangement processes. Epidermal growth factor receptor (EGFR)-signaling tightly correlates with tumor progression in head and neck squamous cell carcinomas (HNSCCs), and has previously been implicated in the regulation of cytokeratin (CK) expression. In this study, HNSCC cell lines were treated with EGF, and CK expression levels were monitored by Western blot analysis. Changes in cellular morphology were documented by fluorescence- and atomic force microscopy. Some of the cell lines demonstrated an EGF-dependent modulation of CK expression levels. Interestingly, regression of some CK subtypes or initial up-regulation followed by downregulation at higher EGF-levels could also be observed in the tested cell lines. Overall, the influence of EGF on CK expression levels appeared variable and cell-type-dependent. Real-time cellular analysis of EGF-treated and -untreated HNSCC cell lines demonstrated a rise over time in cellular impedance. In three of the EGF-treated HNSCC cell lines, this rise was markedly higher than in untreated controls, whereas in one of the cell lines the gain of cellular impedance was paradoxically reduced after EGF treatment, which was found to correlate with changes in cellular morphology rather than with relevant changes in cellular viability or proliferation. After treating HNSCC cells with EGF, CK filaments frequently appeared diffusely distributed throughout the cytoplasm, and in some cases were found in a perinuclear localization, the latter being reminiscent to observations by other groups. In summary, the data points to a possible role of EGFR in modulating HNSCC cell morphology.

Detection of cytokeratins in normal and malignant laryngeal epithelia by means of reverse transcriptase-polymerase chain reaction

Cytokeratins (CKs) are a subgroup of intermediate filament proteins that take part in forming the cytoskeleton. The epithelial cells in different organs express distinct CKs, and this expression may be modified during malignant transformation. Here we describe the use of reverse transcriptase-polymerase chain reaction followed by Southern blotting to determine the profile of expression of CKs in both normal and malignant laryngeal samples. Thirty-six samples were subjected to histologic examination and classified as 17 squamous cell carcinomas, 3 dysplastic lesions, and 16 normal samples. CK8 and CK19 were expressed in almost all samples, both cancerous and normal, and were therefore used to verify the integrity of RNA. Expression of CK2, CK9, and CK20 was not detected in any of the samples, normal or cancerous. CK15 and CK18 showed low sensitivity for detection of cancer (36.4% and 45.5%, respectively). CK10 showed relatively high sensitivity (91%), but only moderate specificity (69.2%). Only CK17 showed both high sensitivity and specificity (91% and 92.3%, respectively; positive predictive value, 91%). We propose that CK17 may be considered a promising candidate to use as a molecular marker for malignant transformation in laryngeal squamous cell carcinoma.

Cytokeratin and vimentin expression in normal epithelium and squamous cell carcinomas of the larynx

The immunohistochemical expression patterns of cytokeratin polypeptides and vimentin were investigated in normal epithelia and squamous cell carcinomas of the larynx with special emphasis on tumor grading. During malignant transformation of epithelial cells, the cytokeratin expression patterns changed, depending on the differentiation grade of the carcinomas. In low-grade carcinomas, the expression patterns were close to those of the normal epithelium. With increasing tumor grade, there was decreased expression of stratification cytokeratins and increased expression of basal cell, simple cell and hyperproliferation-related cytokeratins. Increasing tumor grade was also associated with the expression of vimentin, a cytoskeletal protein of mesenchymal cells. No relationship was found between vimentin expression and the presence of lymph-node metastases.