Possible involvement of ΔNp63 downregulation in the invasion and metastasis of oral squamous cell carcinoma via induction of a mesenchymal phenotype.

Epithelial-to-mesenchymal transition (EMT), an essential developmental program, is involved in tumor progression. ΔNp63, a homolog of p53, is associated with the EMT program, but the detailed mechanism remains to be elucidated. In this study, we investigated the role of ΔNp63 in EMT during progression of oral squamous cell carcinoma (OSCC). Five OSCC cell lines and specimens from 78 patients with OSCC were used. The expressions of ΔNp63, p63α, p63ß and epithelial markers (cytokeratins 5 and 14) was detected in the OSCC cells, but not in SQUU-B cells (high metastatic potential). E-cadherin was expressed in all OSCC cells. Mesenchymal markers were strongly expressed in the SQUU-B cells. Knockdown of endogenous ΔNp63 in HSC-2 cells induced morphological changes to the spindle shape, decreased the expression of epithelial markers, increased the expression of mesenchymal markers, increased migration and reduced proliferation. By contrast, SQUU-B cells overexpressing ΔNp63ß showed changed their morphology from stromal cell-like to epithelial cells. However, E-cadherin expression was not affected by ΔNp63 knockdown or overexpression. Immunohistochemical staining revealed that cancer cells expressing vimentin were found at the invasive front in the OSCC specimens. The intensity of ΔNp63 expression was also decreased in these cells. Interestingly, the vimentin positivity or decreased intensity of ΔNp63 was positively associated with metastases and poor prognosis in the OSCC patients. These results indicated that ΔNp63 downregulation in cancer cells induces a mesenchymal phenotype that is related to tumor progression of OSCC.

Immunohistochemical location of the p75 neurotrophin receptor (p75NTR) in oral leukoplakia and oral squamous cell carcinoma.

BACKGROUND: Recent studies have demonstrated that the p75 neurotrophin receptor (p75NTR) is a useful marker of keratinocyte stem cells. Although the stem cell markers of original normal tissue have been used to identify cancer stem cells in a variety of cancers, the expression and function of p75NTR have been poorly understood in oral squamous cell carcinoma (OSCC). The objective of this study is, thus, to examine p75NTR expression immunohistochemically in oral leukoplakia (OL), the most frequent precancerous lesion, and OSCC, and to reveal the usefulness of p75NTR as a marker for undifferentiated cancer cells and a novel prognostic factor for OSCC patients. METHODS: In this study immunohistochemical expression of p75NTR, Ki-67, cytokeratin (CK) 5, and CK14 was examined in 112 cases of OL and 81 of OSCC. The labeling indices (LIs) of p75NTR and Ki-67 were calculated, and the association of these LIs with histopathologic characteristics was then evaluated. RESULTS: In the normal oral epithelium and OL, p75NTR was expressed only in the basal layer, and its LI was invariant, irrespective of the extent of epithelial dysplasia. In OSCC, however, p75NTR-LI was significantly increased in association with upgrading of histologic grade and mode of tumor invasion. Furthermore, the prognosis of the high p75NTR-LI group (LI ≥ 53.1%) was poorer than that of the low p75NTR-LI group (LI < 53.1%). CONCLUSIONS: These results suggest that p75NTR is expressed in undifferentiated cell populations in OL and OSCC. Furthermore, p75NTR is possibly involved in invasion and poor prognosis in OSCC.

Association of cytokeratin 17 expression with differentiation in oral squamous cell carcinoma.

PURPOSE: The aim of this study was to confirm the expression profile of cytokeratin (CK)17 in comparison with that of CK13 in oral squamous cell carcinoma (OSCC) and leukoplakia and to clarify an association of CK17 with the OSCC differentiation. MATERIALS: The expression of CK17 and CK13 was immunohistochemically examined in 105 patients with OSCC and 108 patients with leukoplakia. A correlation of CK expression with clinicopathological variables was carried out. The over-expression levels of CK17 mRNA were analyzed by real-time RT-PCR in 5 OSCC cell lines (HSC-2, HSC-3, SAS, SQUU-A, SQUU-B). RESULTS: CK17 and CK13 were detected in 101 (96.2 %) and three (2.9 %) of the 105 OSCCs, respectively. CK17 was significantly expressed in well-differentiated OSCC compared to moderately/poorly differentiated OSCC (p < 0.01). As detected in 19 of the 34 dysplastic leukoplakias (55.9 %) and 36 of the 74 hyperplastic leukoplakias (48.6 %), CK17 was significantly expressed in dysplastic leukoplakias (p < 0.01). As detected in 11 of the 34 dysplastic (32.4 %) and 52 of the 74 hyperplastic leukoplakias (70.3 %), CK13 was significantly expressed in hyperplastic leukoplakias (p < 0.01). The relative expression of CK17 mRNA in HSC-2 was significantly higher than in HSC-3 and SAS (p < 0.05). Moreover, the relative expression of CK17 mRNA in SQUU-A was significantly higher than in SQUU-B (p < 0.05). CONCLUSION: CK17 expression could be associated with the differentiation and the malignancy of OSCC. A combination pattern of CK17/CK13 might be a suitable marker of malignant transformation.

Clinical significance of combined assessment of the maximum standardized uptake value of F-18 FDG PET with nodal size in the diagnosis of cervical lymph node metastasis of oral squamous cell carcinoma.

RATIONALE AND OBJECTIVES: This study aimed to elucidate the diagnostic accuracy of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) for nodal involvement in oral squamous cell carcinoma (OSCC), and to reveal clinically useful factors to distinguish between true-positive (TP) and false-positive (FP) nodes. MATERIALS AND METHODS: Thirty-eight patients with primary OSCC who underwent neck dissection were assessed. The diagnostic accuracy of F-18 FDG PET/CT was evaluated, and then compared with that of CT/ultrasonography (US). Furthermore, the association of the maximum standardized uptake value (SUVmax) and nodal size with the histopathologic findings was examined. RESULTS: Sensitivity and specificity using F-18 FDG PET/CT were 77.1% and 97.3%, and those using CT/US were 72.9% and 98.9%, respectively. The SUVmax of TP nodes was significantly higher than that of FP nodes. Nodes with SUVmax >4.5 were pathologically confirmed as metastasis. Nodes with SUVmax ≤4.5 were further discriminated between TP and FP nodes by using the long axis diameters or the ratios of long to short axis diameter as clinical parameters. Positive correlation between the SUVmax and the short-axis diameter was found in TP nodes. The AUC obtained from the ROC curves of the SUVmax alone (AUC, 0.804) was improved by combination with the long-axis diameter (AUC, 0.867) or the short-axis diameter (AUC, 0.846), although no significant difference was found. CONCLUSIONS: These results indicated that F-18 FDG PET/CT was potentially useful in diagnosing preoperative nodal state. Furthermore, combined assessment of SUVmax with nodal size could be significant in the identification of metastatic lymph nodes in OSCC patients.

Increased ΔNp63 expression is predictive of malignant transformation in oral epithelial dysplasia and poor prognosis in oral squamous cell carcinoma.

This study examined immunohistochemical expression of ΔNp63, a keratinocyte stem cell marker, in oral leukoplakia (OL) and oral squamous cell carcinoma (OSCC) and then to elucidate usefulness of ΔNp63 as a marker for diagnosis and prognosis. One-hundred and twelve cases of OL and 81 cases of OSCC were analyzed by immunohistochemical staining for ΔNp63, Ki-67, and cytokeratin 14. These labeling indices (LIs) were calculated, and the association of these LIs with clinicopathologic characteristics in the OL and OSCC was evaluated. In the OL, these LIs increased significantly according to the severity of epithelial dysplasia (p<0.0001). ΔNp63-LI in the OL with malignant transformation was significantly higher than that in the OL without (49.3 vs. 34.2%; p<0.01). In the OSCC, the LIs increased significantly in association with the histologic grade (p<0.0001). A significant difference between the high and low ΔNp63-LI groups was found in the incidence of cervical lymph node and distant metastasis (p<0.05). The prognosis of the high ΔNp63-LI (mean value >73.8%) group is poorer than that of the low ΔNp63-LI (mean value ≤73.8%) group (p<0.05). These results suggested that increased ΔNp63 expression is involved in malignant transformation in epithelial dysplasia and poor prognosis in OSCC.