Tetsuo Ogushi

Increased expression of estrogen-related receptor alpha (ERRalpha) is a negative prognostic predictor in human prostate cancer.

The nuclear receptor ERRα (estrogen‐related receptor α) is known to modulate the estrogen‐signaling pathway, but the biological significance of ERRα in the prostate remains unclear. We investigated the expression of ERRα in human prostate tissues and cancer cell lines to evaluate the potential roles of the receptor in prostate cancer (PC). Western blot analysis of ERRα was performed in three cell lines of human PC (LNCaP, DU145 and PC‐3). The expressions of ERRα in cancerous lesions (n = 106) and benign foci (n = 99) of 106 surgically obtained prostate specimens were evaluated by immunohistochemistry. The relationships between the ERRα expression and clinicopathological features were evaluated. Western blot analysis using the polyclonal anti‐ERRα antibody detected a 52 kD band in all three PC cell lines. Positive immunostaining of ERRα in the nuclei was found in 73 (69%) cancerous and 47 (47.5%) benign epithelium, whereas the stromal tissues were negative for ERRα. The mean immunoreactivity score (IR score) of the cancerous lesions (3.5 ± 2.6) was significantly higher than that of the benign foci (1.8 ± 2.1) (p < 0.0001). The IR score of the cancerous lesions significantly correlated with the Gleason score (p = 0.0135). Univariate and multivariate hazard analyses revealed significant correlations between elevated ERRα expression and poor cancer‐specific survival (p = 0.0141 and 0.0367, respectively). The enhanced expression of ERRα might play a role in the development of human PC and serve as a significant prognostic factor for the disease.

Estrogen Receptor-Binding Fragment-Associated Antigen 9 Is a Tumor-Promoting and Prognostic Factor for Renal Cell Carcinoma

The estrogen receptor-binding fragment-associated antigen 9 (EBAG9) has been identified as a primary estrogen-responsive gene in human breast cancer MCF7 cells. A high expression of EBAG9 has been observed in invasive breast cancer and advanced prostate cancer, suggesting a tumor-promoting role of the protein in malignancies. Here we show that intratumoral (i.t.) administration of small interfering RNA against EBAG9 exerted overt regression of tumors following s.c. implantation of murine renal cell carcinoma (RCC) Renca cells. Overexpression of EBAG9 did not promote the proliferation of culture Renca cells; however, the inoculated Renca cells harboring EBAG9 (Renca-EBAG9) in BALB/c mice grew faster and developed larger tumors compared with Renca cells expressing vector alone (Renca-vector). After renal subcapsular implantation, Renca-EBAG9 tumors significantly enlarged compared with Renca-vector tumors in BALB/c mice, whereas both Renca-EBAG9 and Renca-vector tumors were developed with similar volumes in BALB/c nude mice. No apparent difference was observed in specific cytotoxic T-cell responses against Renca-EBAG9 and Renca-vector cells; nonetheless, the number of infiltrating CD8+ T lymphocytes was decreased in Renca-EBAG9 subcapsular tumors. Furthermore, immunohistochemical study of EBAG9 in 78 human RCC specimens showed that intense and diffuse cytoplasmic immunostaining was observed in 87% of the cases and positive EBAG9 immunoreactivity was closely correlated with poor prognosis of the patients. Multivariate analysis revealed that high EBAG9 expression was an independent prognostic predictor for disease-specific survival (P = 0.0485). Our results suggest that EBAG9 is a crucial regulator of tumor progression and a potential prognostic marker for RCC.

Expression of Cytochrome P450 3A4 and Its Clinical Significance in Human Prostate Cancer

OBJECTIVES To evaluate CYP3A4 expression in human prostrate cancer (PCa) tissues. Enzymes of the cytochrome P450 (CYP) family are key inactivators of testosterone in the liver and prostate. We previously reported that CYP2B6 is a growth-inhibitory and prognostic factor in human PCa; however, the status of CYP3A4 in PCa remains unclear. METHODS We used immunohistochemistry to analyze CYP3A4 expression in 107 human PCa specimens obtained by radical prostatectomy. Stained slides were evaluated for the proportion and staining intensity of positively stained cells. Total immunoreactivity scores (0-8) were obtained as the sum of the proportion and intensity scores. In addition, we estimated the relationship between CYP3A4 status and clinicopathologic features. RESULTS CYP3A4 immunoreactivity was identified in the cytoplasm of prostate cells. The CYP3A4 immunoreactive PCa score (3.6+/-2.6) was significantly lower than that of benign epithelium (4.5+/-2.1; P < .0001). In addition, CYP3A4 immunoreactivity correlated inversely with the Gleason score (P < .0001). Decreased CYP3A4 immunoreactivity was significantly related to a poor prognosis in human PCa (P = .0175). CONCLUSIONS We demonstrated differential CYP3A4 expression in prostatic tissues, indicating that decreased CYP3A4 expression may contribute to the development of PCa.

Interleukin-2 blocks the antitumour activity caused by depletion of CD25 cells in a murine renal adenocarcinoma model.

To test the effectiveness of antimouse CD25 monoclonal antibody (mAb) against murine renal adenocarcinoma (RENCA) cells, as immunoregulatory/suppressor cells are known to be involved in tumour development in vivo, but the functions of these cells are not yet clear, and eliminating naive CD25 (interleukin‐2 receptor α)‐positive T cells elicits potent immune responses to syngeneic tumours in vivo.

EBAG9 is a tumor-promoting and prognostic factor for bladder cancer

Upregulation of EBAG9 expression has been observed in several malignant tumors such as advanced breast and prostate cancers, indicating that EBAG9 may contribute to tumor proliferation. In the present study, we assess the role of EBAG9 in bladder cancer. We generated human bladder cancer EJ cells stably expressing FLAG‐tagged EBAG9 (EJ‐EBAG9) or empty vector (EJ‐vector), and investigated whether EBAG9 overexpression modulates cell growth and migration in vitro as well as the in vivo tumor formation of EJ transfectants in xenograft models of BALB/c nude mice. EBAG9 overexpression promoted EJ cell migration, while the effect of EBAG9 to cultured cell growth was rather minimal. Tumorigenic experiments in nude mice showed that the size of EJ‐EBAG9‐derived tumors was significantly larger than EJ‐vector‐derived tumors. Loss‐of‐function study for EBAG9 using small interfering RNA (siRNA) in xenografts with parental EJ cells showed that the intra‐tumoral injection of EBAG9 siRNA markedly reduced the EJ tumor formation compared with control siRNA. Furthermore, immunohistochemical study for EBAG9 expression was performed in 60 pathological bladder cancer specimens. Intense and diffuse cytoplasmic immunostaining was observed in 45% of the bladder cancer cases. Positive EBAG9 immunoreactivity was closely correlated with poor prognosis of the patients (p = 0.0001) and it was an independent prognostic predictor for disease‐specific survival in multivariate analysis (p = 0.003). Our results indicate that EBAG9 would be a crucial regulator of tumor progression and a potential prognostic marker for bladder cancer.

Estrogen receptor-binding fragment-associated gene 9 expression and its clinical significance in human testicular cancer

Objectives:  We previously demonstrated that estrogen receptor‐binding fragment‐associated gene 9 (EBAG9) is a tumor promoting factor in renal cell carcinoma (Ogushi T, Cancer Res. 2005; 65: 3700). Here, we evaluated EBAG9 expression and its clinical significance in normal and malignant human testicular tissues.