Decreased expression of kallikrein-related peptidase 13: possible contribution to metastasis of human oral cancer.

The human kallikrein-related peptidase family is comprised of 15 serine protease genes on chromosome 19q13.4. Our previous microarray analyses showed that the gene kallikrein-related peptidase 13 (KLK13) was down-regulated in oral squamous cell carcinoma (OSCC) cell lines. We evaluated the expression status of KLK13 in primary OSCCs and performed functional molecular experiments in OSCC cell lines. In 102 primary tumors studied, KLK13 expression significantly (P < 0.05) decreased compared with matched normal counterparts. Interestingly, KLK13-negative cases correlated significantly (P < 0.05) with regional lymph node metastasis. In vitro, cells overexpressing KLK13 (oeKLK13) had decreased invasiveness and motility and up-regulation of adhesion molecules (E-cadherin, α-catenin, ß-catenin, junction plakoglobin, plakophilin4, desmocollin2, desmoglein3, and desmoplakin) compared with control cells. A rescue experiment that transfected oeKLK13 cells with siRNA against KLK13 restored invasiveness and migration activities with down-regulated adhesion molecules. Based on our results, we concluded that KLK13 may play an important role in regulating cellular migration and invasiveness, making the loss of KLK13 a potential biomarker for early detection of lymph node metastasis in OSCCs.

Dickkopf-1 in human oral cancer.

Dickkopf-1 (Dkk1), a negative regulator of the Wnt signaling pathway, is implicated in tumorigenesis in several types of cancer. The purpose of this study was to determine the involvement of Dkk1 in oral squamous cell carcinoma (OSCC). We found that Dkk1 is frequently upregulated in OSCC-derived cell lines and primary OSCCs compared with normal counterparts. Unexpectedly, Dkk1-positive cases were correlated significantly (P<0.05) with a low risk of regional lymph node metastasis. We also found that cellular migration and invasiveness increased in Dkk1 knockdown cells and decreased in Dkk1 overexpressed cells. Furthermore, we investigated the relationship between the expression of Dkk1 and distribution of ß-catenin in OSCC cells, since the Wnt signaling pathway is related closely to ß-catenin. Whereas alteration of the ß-catenin levels was not observed in each subcellular fractionation, the phosphorylated ß-catenin levels in nuclei increased in Dkk1 knockdown cells and decreased in Dkk1 overexpressed cells. These data indicated that the high phosphorylation level of ß-catenin in nuclei was correlated with a high risk of tumor invasiveness. The current study suggested that Dkk1 plays an important role in regulating cellular migration and invasiveness, making Dkk1 a potential biomarker for early detection of lymph node metastasis in OSCCs.

Antitumor activity of satraplatin in cisplatin-resistant oral squamous cell carcinoma cells.

BACKGROUND: The aim of the current study was to identify the antitumor activity of satraplatin in paired cisplatin (CDDP)-resistant oral squamous cell carcinoma (OSCC) cell line and its parental cell line. METHODS: CDDP-resistant (KB-R) cells and parental cells (KB) pair were used. Viability was assessed using the MTT and clonogenic assay. Real-time polymerase chain reaction (PCR), glutathione (GSH) assay, and flow cytometric analysis were used for further assessment. RESULTS: KB-R cells did not show cross-resistance to satraplatin. The expression status of almost all transporters was upregulated in the KB-R cells. There was no difference in the GSH levels between the KB and KB-R cells. Flow cytometric analysis indicated that with satraplatin the G2/M phase was arrested in the KB-R cells. KB-R cells contain enriched side population cells. CONCLUSION: These data suggested that satraplatin has antitumor activity against the CDDP-resistant OSCC cells. The mechanism of cross-resistance to platinum agents seems to be multifactorial.

State of homeobox A10 expression as a putative prognostic marker for oral squamous cell carcinoma.

Homeobox (HOX) A10, the regulator of embryonic morphogenesis and differentiation, is aberrantly expressed in several cancer types. Our previous study using microarray technology showed that significant up-regulation of HOXA10 occurs in oral squamous cell carcinoma (OSCC)-derived cell lines compared to human normal oral keratinocytes (HNOKs). The aim of the current study was to examine the status of HOXA10 mRNA and protein expression in OSCC-derived cell lines and human primary OSCCs. HOXA10 mRNA was up-regulated in six OSCC-derived cell lines compared with HNOKs and in primary OSCCs by using real-time quantitative reverse transcriptase-polymerase chain reaction. Immunohistochemistry data indicated that HOXA10 protein expression levels were consistent with mRNA expression status in OSCC-derived cell lines and primary OSCCs. Furthermore, HOXA10 expression status was correlated with the TNM stage (P<0.05). These results indicate that HOXA10 expression could contribute to cancer progression and prognosis and that HOXA10 may be a potential diagnostic marker and a therapeutic target for OSCCs.

Expression status of Zic family member 2 as a prognostic marker for oral squamous cell carcinoma.

PURPOSE: To determine the involvement of ZIC2 in oral squamous cell carcinoma (OSCC). METHODS: ZIC2 mRNA and protein expression in primary OSCCs (n = 74), oral premalignant lesions (OPLs, n = 20) and five OSCC-derived cell lines (HSC-2, HSC-3, OK-92, H1, and Sa3) were analyzed by quantitative reverse transcriptase-polymerase chain reaction, Western blot and immunohistochemistry (IHC). In addition, we evaluated the correlation between ZIC2 IHC scores in OSCCs and the clinicopathologic status. RESULTS: Significant up-regulation of ZIC2 was detected in OSCC-derived cell lines (P < 0.05), primary OSCCs (P < 0.05) and OPLs (P < 0.05) compared with normal counterparts. Among the clinical variables analyzed, ZIC2 expression was associated with the histopathologic types of OSCC. Furthermore, the survival rates differed significantly between ZIC2-positive cases and ZIC2-negative cases. CONCLUSIONS: These results suggested that ZIC2 expression is correlated with the differentiation type of OSCC and diagnosis and might be a potential prognostic indicator and therapeutic target for OSCCs.