Bone morphogenetic protein receptor in the osteogenic differentiation of rat bone marrow stromal cells.

PURPOSE: Several signaling pathways have been shown to regulate the lineage commitment and terminal differentiation of bone marrow stromal cells (BMSCs). Bone morphogenetic protein (BMP) signaling has important effects on the process of skeletogenesis. In the present study, we tested the role of bone morphogenetic protein receptor (BMPR) in the osteogenic differentiation of rat bone marrow stromal cells in osteogenic medium (OM) with or without BMP-2. MATERIALS AND METHODS: BMSCs were harvested from rats and cultured in OM containing dexamethasone, beta-glycerophosphate, and ascorbic acid, with or without BMP-2 in order to induce osteogenic differentiation. The alkaline phosphatase (ALP) activity assay and von kossa staining were used to assess the osteogenic differentiation of the BMSCs. BMPR mRNA expression was assessed using reverse transcriptionpolymerase chain reaction (RT-PCR). RESULTS: The BMSCs that underwent osteogenic differentiation in OM showed a higher level of ALP activity and matrix mineralization. BMP-2 alone induced a low level of ALP activity and matrix mineralization in BMSCs, but enhanced the osteogenic differentiation of BMSCs when combined with OM. The OM significantly induced the expression of type IA receptor of BMPR (BMPRIA) and type II receptor of BMPR (BMPRII) in BMSCs after three days of stimulation, while BMP-2 significantly induced BMPRIA and BMPRII in BMSCs after nine or six days of stimulation, respectively. CONCLUSION: BMSCs commit to osteoblastic differentiation in OM, which is enhanced by BMP-2. In addition, BMP signaling through BMPRIA and BMPRII regulates the osteogenic differentiation of rat BMSCs in OM with or without BMP-2.

Deregulation of manganese superoxide dismutase (SOD2) expression and lymph node metastasis in tongue squamous cell carcinoma.

BACKGROUND: Lymph node metastasis is a critical event in the progression of tongue squamous cell carcinoma (TSCC). The identification of biomarkers associated with the metastatic process would provide critical prognostic information to facilitate clinical decision making. Previous studies showed that deregulation of manganese superoxide dismutase (SOD2) expression is a frequent event in TSCC and may be associated with enhanced cell invasion. The purpose of this study is to further evaluate whether the expression level of SOD2 is correlated with the metastatic status in TSCC patients. METHODS: We first examined the SOD2 expression at mRNA level on 53 TSCC and 22 normal control samples based on pooled-analysis of existing microarray datasets. To confirm our observations, we examined the expression of SOD2 at protein level on an additional TSCC patient cohort (n = 100), as well as 31 premalignant dysplasias, 15 normal tongue mucosa, and 32 lymph node metastatic diseases by immunohistochemistry (IHC). RESULTS: The SOD2 mRNA level in primary TSCC tissue is reversely correlated with lymph node metastasis in the first TSCC patient cohort. The SOD2 protein level in primary TSCC tissue is also reversely correlated with lymph node metastasis in the second TSCC patient cohort. Deregulation of SOD2 expression is a common event in TSCC and appears to be associated with disease progression. Statistical analysis revealed that the reduced SOD2 expression in primary tumor tissue is associated with lymph node metastasis in both TSCC patient cohorts examined. CONCLUSIONS: Our study suggested that the deregulation of SOD2 in TSCC has potential predictive values for lymph node metastasis, and may serve as a therapeutic target for patients at risk of metastasis.

Dysregulation of heat shock protein 27 expression in oral tongue squamous cell carcinoma.

BACKGROUND: Recent proteomic studies identified Hsp27 as a highly over-expressed protein in oral squamous cell carcinoma (OSCC). Clinical studies that attempted to evaluate the prognostic values of Hsp27 yielded inconsistent results, which may be due to inclusion of OSCC cases from multiple anatomic sites. In this study, to determine the utility of Hsp27 for prognosis, we focused on oral tongue SCC (OTSCC), one of the most aggressive forms of OSCC. METHODS: Archival clinical samples of 15 normal oral tongue mucosa, 31 dysplastic lesions, 80 primary OTSCC, and 32 lymph node metastases were examined for Hsp27 expression by immunohistochemistry (IHC). Statistical analyses were carried out to assess the prognostic value of Hsp27 expression for patients with this disease. RESULTS: Dysregulation of Hsp27 expression was observed in dysplastic lesions, primary OTSCC, and lymph node metastases, and appears to be associated with disease progression. Statistical analysis revealed that the reduced Hsp27 expression in primary tumor tissue was associated with poor differentiation. Furthermore, the higher expression of Hsp27 was correlated with better overall survival. CONCLUSION: Our study confirmed that the dysregulation of Hsp27 expression is a frequent event during the progression of OTSCC. The expression of Hsp27 appears to be an independent prognostic marker for patients with this disease.

Retinoic acid inhibits osteogenic differentiation of rat bone marrow stromal cells.

It has been well established that all-trans-retinoic acid (ATRA) influences bone metabolism when given in the treatment or prevention of cancer. However, the molecular mechanisms underlying this are unknown. In the present study, we investigated the effect of ATRA on differentiation of rat bone marrow stromal cells (BMSCs). BMSCs were harvested from rats and induced to differentiate in the presence or absence of ATRA in either osteogenic (OM) or control medium (CM). BMSCs underwent osteogenic differentiation, showed alkaline phosphatase (ALP) activity, a high level of matrix mineralization, and expressed osteonectin when cultured in OM. Although ATRA induced ALP activity, it failed to induce matrix mineralization and osteonectin, decrease mineralization in OM, and induce lipid accumulation in BMSCs. Moreover, while ATRA induced the expression of BMP-RIA, both BMP-RII and Smad5 mRNA were induced by OM and ATRA. Thus, ATRA inhibited osteogenesis and promoted adipogenesis of BMSCs. BMP signaling cooperated with ATRA in the differentiation of BMSCs.

Proteomic based identification of manganese superoxide dismutase 2 (SOD2) as a metastasis marker for oral squamous cell carcinoma.

Metastasis is a critical event in oral squamous cell carcinoma (OSCC) progression. To identify proteomic biomarkers for OSCC metastasis, 3 paired OSCC cell lines (UM1/UM2, 1386Tu/1386Ln, 686Tu/686Ln) with different metastatic potential were examined. Among those 3 cell lines, UM1, 1386Ln and 686Ln exhibited a higher degree of metastatic potential than their paired cell lines UM2, 1386Tu and 686Tu, respectively, as measured using an in vitro cell invasion assay. A total of 40 differentially expressed proteins were identified using 2D-PAGE/MS proteomic approach. Selected protein candidates (superoxide dismutase 2 and heat shock protein 27) were further investigated by immuno-histochemistry (IHC) method using independent OSCC patient tissue samples. The statistically significantly increases in IHC staining for manganese superoxide dismutase 2 (SOD2) were observed in lymph node metastatic disease when compared with the paired primary OSCC. Our results thus indicated that elevated SOD2 levels is associated with lymph node metastasis in OSCC and may provide predictive values for diagnosis of metastasis.