Tumor Proteins D52 and D54 Have Opposite Effects on the Terminal Differentiation of Chondrocytes.

The tumor protein D (TPD) family consists of four members, TPD52, TPD53, TPD54, and TPD55. The physiological roles of these genes in normal tissues, including epidermal and mesenchymal tissues, have rarely been reported. Herein, we examined the expression of TPD52 and TPD54 genes in cartilage in vivo and in vitro and investigated their involvement in the proliferation and differentiation of chondrocytes in vitro. TPD52 and TPD54 were uniformly expressed in articular cartilage and trabecular bone and were scarcely expressed in the epiphyseal growth plate. In MC3T3E-1 cells, the expressions of TPD52 and TPD54 were increased in a differentiation-dependent manner. In contrast, their expressions were decreased in ATDC5 cells. In ATDC5 cells, overexpression of TPD52 decreased alkaline phosphatase (ALPase) activity, while knock-down of TPD52 showed little effect. In contrast, overexpression of TPD54 enhanced ALPase activity, Ca2+ deposition, and the expressions of type X collagen and ALPase genes, while knock-down of TPD54 reduced them. The results revealed that TPD52 inhibits and that TPD54 promotes the terminal differentiation of a chondrocyte cell line. As such, we report for the first time the important roles of TPD52 and TPD54, which work oppositely, in the terminal differentiation of chondrocytes during endochondral ossification.

Opposite effects of tumor protein D (TPD) 52 and TPD54 on oral squamous cell carcinoma cells.

The tumor protein D52 (TPD52) protein family includes TPD52, -53, -54 and -55. Several reports have shown important roles for TPD52 and TPD53, and have also suggested the potential involvement of TPD54, in D52-family physiological effects. Therefore, we performed detailed expression analysis of TPD52 family proteins in oral squamous cell carcinoma (OSCC). Towards this end, TPD54-overexpressing or knocked-down cells were constructed using OSCC-derived SAS, HSC2 and HSC3 cells. tpd52 or tpd53 was expressed or co-expressed in these cells by transfection. The cells were then analyzed using cell viability (MTT), colony formation, migration, and invasion assays. In OSCC-xenograft experiments, the cells were transplanted into nude mice together with injection of anti-tpd siRNAs. MTT assay of cell monolayers showed little differences in growth of the transfected cells. tpd54 overexpression in SAS cells significantly decreased colony formation in an anchorage-independent manner. Additionally, knock-down of tpd54 enhanced the number of colonies formed and overexpression of tpd52 in tpd54 knock-down cells increased the size of the colonies formed. The chemotaxis assay showed that tpd54 overexpression decreased cell migration. In the OSCC-xenograft in vivo study, tpd54 overexpression slightly attenuated tumor volume in vivo, despite the fact that tumor metastasis or cell survival was not involved. Our results showed that TPD54 not only downregulated anchorage-independent growth and cell migration in vitro, but also attenuated tumor growth in vivo. Based on these results, it is considered that TPD54 might act as a negative regulator of tumor progression in OSCC cells.

Tumor protein D52 expression is post-transcriptionally regulated by T-cell intercellular antigen (TIA) 1 and TIA-related protein via mRNA stability.

Although tumor protein D52 (TPD52) family proteins were first identified nearly 20 years ago, their molecular regulatory mechanisms remain unclear. Therefore, we investigated the post-transcriptional regulation of TPD52 family genes. An RNA immunoprecipitation (RIP) assay showed the potential binding ability of TPD52 family mRNAs to several RNA-binding proteins, and an RNA degradation assay revealed that TPD52 is subject to more prominent post-transcriptional regulation than are TPD53 and TPD54. We subsequently focused on the 3'-untranslated region (3'-UTR) of TPD52 as a cis-acting element in post-transcriptional gene regulation. Several deletion mutants of the 3'-UTR of TPD52 mRNA were constructed and ligated to the 3'-end of a reporter green fluorescence protein gene. An RNA degradation assay revealed that a minimal cis-acting region, located in the 78-280 region of the 5'-proximal region of the 3'-UTR, stabilized the reporter mRNA. Biotin pull-down and RIP assays revealed specific binding of the region to T-cell intracellular antigen 1 (TIA-1) and TIA-1-related protein (TIAR). Knockdown of TIA-1/TIAR decreased not only the expression, but also the stability of TPD52 mRNA; it also decreased the expression and stability of the reporter gene ligated to the 3'-end of the 78-280 fragment. Stimulation of transforming growth factor-ß and epidermal growth factor decreased the binding ability of these factors, resulting in decreased mRNA stability. These results indicate that the 78-280 fragment and TIA-1/TIAR concordantly contribute to mRNA stability as a cis-acting element and trans-acting factor(s), respectively. Thus, we here report the specific interactions between these elements in the post-transcriptional regulation of the TPD52 gene.

Methanol and Butanol Extracts of Paeonia lutea Leaves Repress Metastasis of Squamous Cell Carcinoma.

Squamous cell carcinoma (SCC) is one of the most common cancers of the head and neck region worldwide and is generally treated surgically in combination with radiotherapy and/or chemotherapy. However, anticancer agents have numerous serious side effects, and alternative, less toxic agents that are effective as chemotherapeutics for SCC are required. The Paeoniaceae family is widely used in traditional Chinese medicine. We examined methanol and butanol extracts of Paeonia lutea (P. lutea) leaves for their potential as an anticancer agent. Both extracts decreased the proliferation of SCC cells, induced apoptotic cell death, and modulated migration, adhesion, chemotaxis, and haptotaxis in an extracellular matrix- (ECM-) dependent manner due to altered expression of several integrin subunits. Subsequently, SCC cells were subcutaneously transplanted into athymic nude mice; the extracts reduced the metastasis of SCC cells but had little effect on the volume of the primary tumor or survival or body weight of the mice. The results suggest that the extracts may hold promise for preventing cancer metastasis.

Aberrant expression of EZH2 is associated with pathological findings and P53 alteration.

AIM: Enhancer of zeste homolog-2 (EZH2) and B lymphoma Mo-MLV insertion region-1 homolog (BMI1) are members of the polycomb group of proteins, which function as transcriptional repressors through chromatin modification. EZH2 forms part of the polycomb repressive complex (PRC)-2, while BMI1 is a component of PRC1. Previous studies have shown that EZH2 is highly expressed in various type of cancers. Expression of EZH2 is reported to be regulated by the P53-E2F/retinoblastoma (RB)-related pathway, and a correlation between P53 mutation and EZH2 expression was recently found in breast cancer. Here, we examined the relationship between P53 and EZH2 in oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: Using immunohistochemistry, we investigated the expression of EZH2 and BMI1 in 99 surgically-resected OSCC and 34 epithelial dysplasia samples. We analyzed associations between aberrant expression of EZH2 and BMI1, and clinicopathological findings and patient outcome. P53 expression was also examined and analyzed in relation to EZH2 and BMI1 expression. RESULTS: EZH2 and BMI1 protein were up-regulated in OSCC tissues compared with epithelial dysplasia and normal epithelium. Aberrant EZH2 and BMI1 protein expression was observed in 32 and 59 of the 99 OSCC samples, respectively. Aberrant EZH2 and BMI1 expression was significantly associated with mode of invasion, but not with lymph node metastasis or survival rate. Aberrant EZH2 expression was associated with P53 alteration in OSCC tissue. Expression of EZH2 mRNA in SAS/neo cells, which have wild-type P53, was significantly lower than in SAS/mp53 cells that have a mutant P53 gene. CONCLUSION: P53 alteration may be involved in dysregulated EZH2 expression, and aberrant expression of EZH2 may play a role in carcinogenesis of OSCC.