Purpose: The histone deacetylase inhibitor FK228 shows strong activity as a potent antitumor drug but its precise mechanism is still obscure. The purpose of this study is to reveal the effect of FK228 on gene expression in the cell and to determine the mechanism of the antitumor activity of FK228 for further clinical applications. Experimental Design and Results: Microarray analysis was applied to verify the gene expression profiles of 4,608 genes after FK228 treatment using human esophageal squamous cell cancer cell lines T.Tn and TE2. Among them, peroxiredoxin 1 (Prdx1), a member of the peroxiredoxin family of antioxidant enzymes having cell growth suppression activity, as well as p21 WAF1 , were significantly activated by FK288. In addition, FK228 strongly inhibited the cell growth of T.Tn and TE2 by the induction of apoptosis. Further, chromatin immunoprecipitation analysis revealed that FK228 induced the accumulation of acetylated histones H3 and H4 in Prdx1 promoter, including the Sp1-binding site. In mouse xenograft models of T.Tn and TE2 cells, FK228 injection resulted in significant tumor regression as well as activated Prdx1 expression in tumor tissues. Prdx1 suppression by RNA interference hindered the antitumor effect of FK228. Conclusion: Our results indicate that the antitumor effect of FK228 in esophageal cancer cells is shown at least in part through Prdx1 activation by modulating acetylation of histones in the promoter, resulting in tumor growth inhibition with apoptosis induction.

A case of so-called inflammatory pseudotumor (IPT), occurring in the spleen of a 77-year-old woman, is reported. The spleen contained a well-circumscribed mass with central hemorrhage and necrosis. Histologically, spindle cells were dispersed in a background of abundant inflammatory cells, predominantly lymphocytes and plasma cells. The cells possessed enlarged, sometimes twisted or irregularly folded, nuclei that contained vesicular chromatin, and small but distinct, centrally located nucleoli. Immunohistochemically, the spindle cells were diffusely positive for vimentin, and focally positive for follicular dendritic cell (FDC) markers (Ber-MAC-DRC for CD35 and CNA.42). The Epstein-Barr virus (EBV) was exclusively detected in the spindle cells by in situ hybridization analysis. The cells also expressed the latent membrane protein-1 (LMP-1) of EBV, and polymerase chain reaction (PCR) analysis revealed that the LMP-1 gene had a 30-bp deletion and three point mutations, although their significance remains controversial. Inflammatory pseudotumor is a descriptive term that encompasses several different entities, and recent investigations have revealed the existence of neoplastic entities among IPT. One of the neoplastic IPT, recently designated 'IPT-like FDC tumor', is characterized by proliferation of EBV-positive FDC and commonly occurs in the liver and spleen. Because such tumors are capable of recurrence and metastasis, it is important to consider the possibility of an IPT-like FDC tumor when making a diagnosis of a hepatic/splenic IPT-like lesion.

BACKGROUND:The expression of Fra-1 (Fos related antigen 1) involves tumor progression and invasion, and its gene ablation could suppress the invasive phenotypes of human tumor cells. The authors investigated the significance of Fra-1 expression in esophageal squamous cell carcinoma (ESCC) and studied the effect of its down-regulation on cell proliferation, motility, and invasion. METHODS: Surgical specimens from 164 patients with ESCC were evaluated. Fra-1 expression in the primary tumor along with metastatic lymph nodes was compared among various clinicopathological characteristics, and overall survival was analyzed. The rate and intensity of Fra-1 immunoreactivity were also investigated. The molecular role of Fra-1 was assessed by its down-regulation in human ESCC cell lines. RESULTS: Fra-1 expression was positive in 127 (77.4%) ESCC patients. Immunoreactivity was localized to the marginal areas of the ESCC tumors. Positive Fra-1 expression correlated with depth of tumor, lymph node metastasis, stage, and infiltrative growth pattern. A significant difference was seen in the survival between tumors with and without Fra-1, and positive Fra-1 expression was revealed to be an independent factor related to poor prognosis. Patients with metastatic lymph nodes with positive Fra-1 expression presented decreased survival compared with negative Fra-1 expression. After the down-regulation of Fra-1 expression, a significant decrease in cell proliferation, motility, and invasion was observed. CONCLUSIONS: This study demonstrated ESCC patients positive for Fra-1 to be associated with poor prognosis. The findings also suggest that Fra-1 regulation may play an important role in the progression of ESCC.

We tested a new therapeutic modality for head and neck and esophageal cancers, a combination of direct intratumoral (i.t.) administration of dendritic cells (DCs) and radiation therapy (RT) in mouse squamous cell carcinoma (SCC). We also evaluated the functions of gp96, which can enhance systemic antitumor activity, and the mechanism of the abscopal effect. Mouse SCC cells (1x10 5), SCCVII, were inoculated into the left femur of C3H/He mice subcutaneously, and also similarly inoculated into chest subcutaneous tissue. Only the left femur tumor was exposed to 4 or 10 Gy of ionizing radiation, and then 1x10 6 DCs i.t. was injected only into the femur tumor. Following this procedure, tumor volumes of the femur and chest were measured. We evaluated whether gp96 could enhance the antitumor effect. With DCs i.t. and RT, tumor growth was markedly suppressed. Tumor growth of non-treated tumors were also suppressed, indicating that the combination therapy of DCs and RT evoked systemic antitumor activity. In vitro, the enhancement of gp96 expression was strongly detected by immunostaining after irradiation, DCs with gp96 induced strong cytotoxic activity in vitro, and tumor growth inhibition was observed by direct i.t. injection of gp96. A combination of DCs i.t. and RT can induce a strong antitumor effect not only against treated local tumor but also against non-treated distant tumor, indicating that this treatment can evoke a strong systemic antitumor effect. Gp96 is thought to be one of the target molecules to explain the abscopal effect.

Abstract. Peroxiredoxins (Prdxs) are a family of antioxidant enzymes that are also known as scavengers of peroxide in mammalian cells. Some reports have shown that the overexpression of Prdx1, which is one of the peroxiredoxins that is a ubiquitously expressed protein, was related to a poor prognosis in several types of human cancers. In this study, we investigated the expression levels of Prdx1 in esophageal squamous cell carcinoma by immunohistochemistry, and the correlation between the Prdx1 expression and the clinical status was elucidated. Immunohistochemical staining was performed in 114 samples which were collected from surgical esophageal cancer specimens. Cytoplasmic staining of Prdx1 was evaluated based on the following scoring criteria: Grade I, negative or weak staining; Grade II, moderate staining; and Grade III, strong staining. The percentage of patients with a Grade I expression of Prx1 was 20% (23 of 114), 44% had Grade II (50 of 114), and 36% had Grade III (41 of 114). The Prdx1 immunoreactivity showed an inverse significant correlation with T-category (P<0.0001), lymph node metastasis (P=0.048), and stage (P=0.001). In addition, the patients with tumors exhibiting a reduced Prdx1 expression had shorter overall survival (P=0.022) in comparison to the patients with tumors which had a higher Prdx1 expression. Currently, Prdx1 has been shown to act as a tumor suppressor. Our results provide strong evidence that the reduced Prdx1 expression is an important factor in esophageal squamous cancer progression and could serve as a useful prognostic marker. IntroductionEsophageal cancer is the eighth most frequent cancer and the sixth most frequent cause of death from malignant disease in the world (1). Esophageal squamous cell carcinoma (ESCC) is the most common type in Japan (2). A large number of reports about genetic changes in ESCC have already been published, but little is known about the major tumor suppressor genes or major oncogenes in the process of tumor progression of this malignant disease. ESCC is still a fatal malignancy with a 5-year rate of 5% to 20% for advanced stage patients undergoing a curative resection (3). This miserable prognosis for ESCC involves not only the aggressive character of this tumor but also the limited number of useful markers available for diagnostic purposes.Therefore, better markers which indicate the malignant potential of ESCC should help in the prognosis or optimal treatment of the patients suffering from this disease. In this study, we focus on Prdx1, one of the peroxiredoxins (Prdxs) belonging to a novel antioxidant family, which has been reported to be a tumor suppressor gene. Prdx1 has been thought to have an inhibitory function for both c-Abl and c-Myc, of which active forms cause several neoplasms (4,5). Neumann et al (6) showed, using Prdx1 knockout mice, that Prdx1 expression correlated with the reactive oxygen species and the incidence of malignant disease. Moreover, our previous study using a cDNA microarray showed that one of the novel histone deacet...