Abstractp63 is a member of the p53 family and regulates crucial events in the formation of epithelial structures, but the role of p63 in tumor is unclear. We found that Snail-induced epithelialto-mesenchymal transition (EMT) is accompanied by downregulation of p63 in human squamous cell carcinomas (SCC). #Np63A is the predominantly expressed p63 isoform in SCC cells. DNp63 promoter activity required a CAAT/enhancer binding protein (C/EBP) binding element and was reduced remarkably by Snail. Down-regulation of #Np63A and reduction of C/EBPA were observed in EMT phenotype cells, which exhibited invasive activity in vitro. p63 knockdown in cells enhanced invasive activity in the presence of E-cadherin. Conversely, forced expression of #Np63A blocked invasive activity of cells with the EMT phenotype. These findings indicate that Snail down-regulates #Np63A, leading to acquisition of the invasive phenotype by SCC. The invasive activity caused by down-regulation of #Np63A does not require down-regulation of E-cadherin.

p63 is a member of the p53 family and DNp63a is the dominantexpressing isoform of p63 in basal layer of normal stratified epithelium and human squamous cell carcinoma (SCC) cells. We have previously reported that down-regulation of p63 was accompanied with epithelial-to-mesenchymal transition (EMT) by Snailexpressing SCC cells, in which re-expression of DNp63a diminished their invasiveness (Higashikawa K, Yoneda S, Tobiume K, Taki M, Shigeishi H, Kamata N. Snail-induced down-regulation of DNp63a acquires invasive phenotype of human squamous cell carcinoma. Cancer Res 2007;67:9207-13). In this study, we found that DNp63a positively regulated inhibitor of differentiation-3 (Id-3) expression. Id is a dominant negative regulator of E2A which is a transcriptional repressor of E-cadherin. Enforced expression of Id-3 was incapable of invoking E-cadherin expression in the SCC cells with EMT phenotype, whereas it significantly impaired their invasiveness with down-regulation of matrix-metalloproteinase-2 (MMP-2) expression. Reporter gene assay revealed that the Ets-1-induced MMP-2 promoter activity was suppressed by the Id-3, while the Id-3-dependent E-cadherin promoter activity was remarkably reduced in the presence of Snail. Furthermore, knockdown of p63 in SCC cells significantly decreased Id-3 expression, in which up-regulation of MMP-2 expression was concomitant with the acquired invasiveness. These findings propose a particular role of the off-signaling of the DNp63a-Id-3 axis incident to Snail-mediated EMT for the MMP-2-dependent invasiveness in SCC cells. ' UICCKey words: Id-3; p63; tumour invasion; squamous cell carcinoma; snail Epithelial-to-mesenchymal transition (EMT) is the process of disaggregating structured epithelial units to enable cell motility and morphogenesis occurring in the restricted events such as embryonic development and wound healing. For the retention of epithelial integrity in the adult organism, E-cadherin plays an important role for the formation of stable cell-cell adhesion. Loss of E-cadherin expression is a primal molecular event on the progression of tumour. 1 During the invasive process, tumour cells frequently undergo EMT, which comprises breakdown of E-cadherin-mediated interaction as an essential process. 2 Snail, a zinc-finger transcription factor, triggers EMT through direct repression of E-cadherin. 3,4 dEF-1, Twist and TGF-b also induce EMT in tumour cells and it accelerates malignancy of tumour. 5,6 In addition, maintenance of cell polarity is also fundamental for the identity of epithelial tissues. DNp63a, the predominant isoform of p63 which belongs to the p53 family, in basal keratinocytes plays a crucial role in the formation of stratified squamous epithelial structures by regulating asymmetric division. 7 We previously found that loss of p63 is accompanied by EMT in human squamous cell carcinoma (SCC) cells, and demonstrated that forced depletion of p63 leads to the acquisition of high-invasive capability independent of E-cadherin. 8 Significantly, the fact that re-exp...

We examined the expression of Centromere protein H (CENP-H) mRNA in 38 oral squamous cell carcinomas (SCCs), 2 epithelial dysplasias and 5 normal gingivae using the real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). The mean expression level of CENP-H mRNA was higher in oral SCCs (0.11±0.08) than epithelial dysplasias (0.03±0.01) and normal gingivae (0.027±0.01). The expression level of CENP-H mRNA was significantly higher in oral SCCs than normal gingivae (Mann-Whitney U test, P=0.005). We also found a significant association between the level of CENP-H mRNA expression and clinical stage in oral SCCs (Mann-Whitney U test, P=0.04). We next studied the expression of CENP-H in 17 oral SCCs immunohistochemically. A significant correlation between the expression levels of CENP-H protein and the Ki-67 labeling index was found (Mann-Whitney U test, P=0.005). These results indicate that human CENP-H is closely linked to the increased or abnormal cell proliferation in malignant conditions.

No abstract

Stromal cell-derived factor 1α (SDF-1α) and its receptor CXCR4 have been implicated in the tumorigenesis, proliferation, and lymph node metastasis of cancer. Here, we report that highly invasive squamous cell carcinoma (SCC) cells with a spindle cell morphology show a strong expression of both SDF-1α and CXCR4. CXCR4 expression and cell migratory activity were further up-regulated by treatment with SDF-1α or TGF-ß1 in these cells. When epithelialmesenchymal transition (EMT) was induced by Snail overexpression in SCC cells with an epithelial phenotype, an increased expression of SDF-1α was observed. Furthermore, SDF-1α and TGF-ß1 up-regulated the expression of CXCR4 and cell migratory activity in these cells. These results indicate that SDF-1α and CXCR4 expressions are possible markers of highly-invasive SCC and regulated by EMT.