Nuclear localization of ß-catenin and expression of target genes are associated with increased Wnt secretion in oral dysplasia.

OBJECTIVES: To evaluate the localization of ß-catenin in oral dysplastic cells, the expression of target genes upregulated in oral dysplasia, and the role of Wnt ligands in these events. MATERIALS AND METHODS: Subcellular localization of total and non-phosphorylated (transcriptionally active) ß-catenin was evaluated by immunofluorescence and biochemical fractionation in dysplastic oral keratinocytes (DOK), non-dysplastic oral keratinocytes (OKF6), oral squamous carcinoma cells (CAL27) and primary oral keratinocytes. Tcf/Lef-dependent transcription was measured by luciferase reporter assays. Expression of target genes, survivin and cyclin D1, was evaluated by RT-qPCR and Western blotting. Wnt secretion was inhibited with the inhibitor of porcupine, C59. Wnt3a and ß-catenin were evaluated in biopsies by tissue immunofluorescence. RESULTS: Immunofluorescence and fractionation experiments showed augmented nuclear ß-catenin (total and transcriptionally active) in DOK, when compared with OKF6 and CAL27 cells. Intriguingly, conditioned medium from DOK promoted nuclear accumulation of ß-catenin and Tcf/Lef-dependent transcription in OKF6 and primary oral keratinocytes, suggesting the participation of secreted factors. Treatment of DOK with C59 decreased Wnt3a secretion, nuclear ß-catenin and the expression of survivin and cyclin D1 at both mRNA and protein levels. Accordingly, DOK secreted higher Wnt3a levels than OKF6, and inhibition of Wnt3a secretion prevented DOK-induced Tcf/Lef-dependent transcription in OKF6. These observations were confirmed in clinical samples, since tissue immunofluorescence analysis showed simultaneous expression of Wnt3a and nuclear ß-catenin in oral dysplasia, but not in healthy mucosa biopsies. CONCLUSION: These data indicate that secretion of Wnt ligands is critical for ß-catenin nuclear localization and expression of target genes in oral dysplasia.

Increased nuclear beta-catenin expression in oral potentially malignant lesions: A marker of epithelial dysplasia

BACKGROUND: Deregulation of beta-catenin is associated with malignant transformation; however, its relationship with potentially malignant and malignant oral processes is not fully understood. The aim of this study was to determine and compare the nuclear beta-catenin expression in oral dysplasia and oral squamous cell carcinoma (OSCC). MATERIAL AND METHODS: Cross sectional study. Immunodetection of beta-catenin was performed on 72 samples, with the following distribution: 21 mild dysplasia, 12 moderate dysplasia, severe dysplasia 3, 36 OSCC including 19 well differentiated, 15 moderately differentiated and 2 poorly differentiated. Through microscopic observation the number of positive cells per 1000 epithelial cells was counted. For the statistical analysis, the Kruskal Wallis test was used. RESULTS: Nuclear expression of beta-catenin was observed in all samples with severe and moderate dysplasia, with a median of 267.5, in comparison to mild dysplasia whose median was 103.75. Only 10 samples (27.7%) with OSCC showed nuclear expression, with statistically significant differences between groups (p < 0.05). CONCLUSIONS: Our results are consistent with most of the reports which show increased presence of beta-catenin in severe and moderate dysplasia compared to mild dysplasia; however the expression of nuclear beta-catenin decreased after starting the invasive neoplastic process. This suggests a role for this protein in the progression of dysplasia and early malignant transformation to OSCC. Immunodetection of beta-catenin could be a possible immune marker in the detection of oral displasia

Increased nuclear ß-catenin expression in oral potentially malignant lesions: A marker of epithelial dysplasia.

BACKGROUND: Deregulation of ß-catenin is associated with malignant transformation; however, its relationship with potentially malignant and malignant oral processes is not fully understood. The aim of this study was to determine and compare the nuclear ß-catenin expression in oral dysplasia and oral squamous cell carcinoma (OSCC). MATERIAL AND METHODS: Cross sectional study. Immunodetection of ß-catenin was performed on 72 samples, with the following distribution: 21 mild dysplasia, 12 moderate dysplasia, severe dysplasia 3, 36 OSCC including 19 well differentiated, 15 moderately differentiated and 2 poorly differentiated. Through microscopic observation the number of positive cells per 1000 epithelial cells was counted. For the statistical analysis, the Kruskal Wallis test was used. RESULTS: Nuclear expression of ß-catenin was observed in all samples with severe and moderate dysplasia, with a median of 267.5, in comparison to mild dysplasia whose median was 103.75. Only 10 samples (27.7%) with OSCC showed nuclear expression, with statistically significant differences between groups (p < 0.05). CONCLUSIONS: Our results are consistent with most of the reports which show increased presence of ß-catenin in severe and moderate dysplasia compared to mild dysplasia; however the expression of nuclear ß-catenin decreased after starting the invasive neoplastic process. This suggests a role for this protein in the progression of dysplasia and early malignant transformation to OSCC. Immunodetection of ß-catenin could be a possible immune marker in the detection of oral dysplasia.