PurposeTo evaluate the outcomes of high-risk prostate cancer patients treated with biologically effective dose (BED) ≥ 220 Gy of high-dose radiotherapy, using low-dose-rate (LDR) brachytherapy in combination with external beam radiotherapy (EBRT) and short-term androgen deprivation therapy (ADT).Material and methodsFrom 2005 to 2013, a total of 143 patients with high-risk prostate cancer were treated by radiotherapy of BED ≥ 220 Gy with a combination of LDR brachytherapy, EBRT, and androgen deprivation therapy (ADT). The high-risk patients in the present study included both high-risk and very high-risk prostate cancer. The number of high-risk features were: 60 patients with 1 high-risk factor (42%), 61 patients with 2 high-risk factors (43%), and 22 patients with 3 high-risk factors (15%) including five N1 disease. External beam radiotherapy fields included prostate and seminal vesicles only or whole pelvis depending on the extension of the disease. Biochemical failure was defined by the Phoenix definition.ResultsSix patients developed biochemical failure, thus providing a 5-year actual biochemical failure-free survival (BFFS) rate of 95.2%. Biochemical failure was observed exclusively in cases with distant metastasis in the present study. All six patients with biochemical relapse had clinical failure due to bone metastasis, thus yielding a 5-year freedom from clinical failure (FFCF) rate of 93.0%. None of the cases with N1 disease experienced biochemical failure. We observed four deaths, including one death from prostate cancer, therefore yielding a cause-specific survival (CSS) rate of 97.2%, and an overall survival (OS) rate of 95.5%.ConclusionsHigh-dose (BED ≥ 220 Gy) radiotherapy by LDR in combination with EBRT has shown an excellent outcome on BFFS in high-risk and very high-risk cancer, although causal relationship between BED and BFFS remain to be explained further.

Patients with a history of non-muscle-invasive bladder cancer sometimes have recurrence of tumors after transurethral resection of bladder tumor treatment. To find factors related to the recurrence of non-muscle-invasive bladder cancer, we examined tissue specimens taken at transurethral resection of bladder tumor as an initial treatment. We revealed the association between prognosis of non-muscle-invasive bladder cancer and infiltration of Foxp3+ T cells that suppress anti-tumor immunity in 115 primary non-muscle-invasive bladder cancer patients retrospectively identified and followed for at least 3 months after primary transurethral resection. In immunohistological staining, we counted the number of cells positive for CD3 and positive for CD3 and Foxp3 together and calculated the percentage of Foxp3+ T cells among the CD3+ T cells. The recurrence-free survival rate was calculated by the Kaplan-Meier method, and a Cox regression analysis of recurrence factors was performed. The median (interquartile range) percentage of Foxp3+ T cells in all cases was 17.1% (11.9, 11.4–23.3%). Compared by risk stratification, it was 11.4% (10.4, 7.8–18.2%) in the low-risk group (n = 32), 16.8% (12.6, 11.6–24.2%) in the intermediate-risk group (n = 45), and 22.0% (9.7, 16.4–26.1%) in the high-risk group (n = 38). The Kaplan-Meier survival analysis indicated that the Foxp3+ T cell high group (≥ 17.1%) had a worse RFS rate than did the low group (< 17.1%) (P = 0.006). In multivariate analysis, the percentage of Foxp3+ T cells was an independent risk factor for intravesical recurrence (hazard ratio 2.25). Thus, peritumoral Foxp3+ T cell infiltration was correlated to risk stratification and recurrence-free survival. Therefore, the percentage of Foxp3+ T cells in tumor specimens may predict a risk for intravesical recurrence.

Selective targeting of drugs to tumor cells is a key goal in oncology. Here, we performed an in vivo phage display to identify peptides that specifically target xenografted prostate cancer cells. This yielded three peptide candidates, LN1 (C-TGTPARQ-C), LN2 (C-KNSMFAT-C), and LN3 (C-TNKHSPK-C); each of these peptides was synthesized and evaluated for binding and biological activity. LN1 showed the highest avidity for LNCaP prostate cancer cells in vitro and was thus administered to tumor-bearing mice to evaluate in vivo binding. Strikingly, LN1 specifically bound to the tumor tissue and exhibited very low reactivity with normal liver and kidney tissues. To demonstrate that LN1 could specifically deliver drugs to prostate cancer tissue, a therapeutic peptide, LN1-KLA (C-TGTPARQ-C-GGG-D[KLAKLAK]2), was prepared and used to treat LNCaP cells in vitro and was also administered to tumor-bearing mice. The therapeutic peptide significantly suppressed growth of the cells both in vitro and in vivo. Our study shows that a selective homing peptide strategy could facilitate cell-specific targeting of therapeutics while avoiding adverse reactions in normal tissues.

Spermatogenesis is controlled by hormonal secretions from the hypothalamus and pituitary gland, by factors produced locally in the testis, and by direct interaction between germ cells and Sertoli cells in seminiferous tubules. Although the mammalian testis contains high levels of D-aspartate (D-Asp), and D-Asp is known to stimulate the secretion of testosterone in cultured Leydig cells, its role in testis is unclear. We describe here biochemical, immunohistochemical, and flow cytometric studies designed to elucidate developmental changes in testicular D-Asp levels and the direct effect of D-Asp on germ cells. We found that the concentration of D-Asp in mouse testis increased with growth and that fluctuations in D-Asp levels were controlled in part by its degradative enzyme, D-aspartate oxidase expressed in Sertoli cells. In vitro sperm production studies showed that mitosis in premeiotic germ cells was strongly inhibited by the addition of D-Asp to the culture medium. Moreover, immunohistochemical analysis demonstrated that d-Asp accumulated in the differentiated spermatids, indicating either transport of D-Asp to spermatids or its de novo synthesis in these cells. Such compartmentation seems to prevent premeiotic germ cells in mouse testis from being exposed to the excess amount of D-Asp. In concert, our results indicate that in mouse testis, levels of D-Asp are regulated in a spatiotemporal manner and that D-Asp functions as a modulator of spermatogenesis.

The growth and progression of cancers are crucially regulated by the tumor microenvironment where tumor cells and stromal cells are mutually associated. In this study, we found that stomatin expression was markedly upregulated by the interaction between prostate cancer cells and stromal cells. Stomatin suppressed cancer cell proliferation and enhanced apoptosis in vitro and inhibited xenograft tumor growth in vivo. Stomatin inhibited Akt activation, which is mediated by phosphoinositide-dependent protein kinase 1 (PDPK1). PDPK1 protein stability was maintained by its binding to HSP90. Stomatin interacted with PDPK1 and interfered with the PDPK1–HSP90 complex formation, resulting in decreased PDPK1 expression. Knockdown of stomatin in cancer cells elevated Akt activation and promoted cell increase by promoting the interaction between PDPK1 and HSP90. Clinically, stomatin expression levels were significantly decreased in human prostate cancer samples with high Gleason scores, and lower expression of stomatin was associated with higher recurrence of prostate cancer after the operation. Collectively, these findings demonstrate the tumor-suppressive effect of stromal-induced stomatin on cancer cells. Significance: These findings reveal that interactions with stromal cells induce expression of stomatin in prostate cancer cells, which suppresses tumor growth via attenuation of the Akt signaling axis.