市川 智彦

Prostate cancer is a major cause of cancer-related deaths among men worldwide. In addition to genomic alterations, epigenetic alterations accumulated in prostate cancer have been elucidated. While aberrant deoxyribonucleic acid hypermethylation in promoter CpG islands inactivates crucial genes associated with deoxyribonucleic acid repair, cell cycle, apoptosis or cell adhesion, aberrant deoxyribonucleic acid hypomethylation can lead to oncogene activation. Acetylation of histone is also deregulated in prostate cancer, which could cause aberrant super-enhancer formation and activation of genes associated with cancer development. Deregulations of histone methylation, such as an increase of trimethylation at position 27 of histone H3 by enhancer of zeste homolog2 overexpression, or other modifications, such as phosphorylation and ubiquitination, are also involved in prostate cancer development, and inhibitors targeting these epigenomic aberrations might be novel therapeutic strategies. In this review, we provide an overview of epigenetic alterations in the development and progression of prostate cancer, focusing on deoxyribonucleic acid methylation and histone modifications.

BACKGROUND: Acquired therapeutic resistance and metastasis/recurrence remain significant challenge in advance renal cell carcinoma (RCC), thus the establishment of patient-derived cancer models may provide a clue to assess the problem. We recently characterized that neuritogenesis-related protein neuritin 1 (NRN1) functions as an oncogene in testicular germ cell tumor. This study aims to elucidate the role of NRN1 in RCC. METHODS: NRN1 expression in clinical RCC specimens was analyzed based on immunohistochemistry. NRN1-associated genes in RCC were screened by the RNA-sequencing dataset from The Cancer Genome Atlas (TCGA). RCC patient-derived cancer cell (RCC-PDC) spheroid cultures were established and their viabilities were evaluated under the condition of gene silencing/overexpression. The therapeutic effect of NRN1-specific siRNA was evaluated in RCC-PDC xenograft models. RESULTS: NRN1 immunoreactivity was positively associated with shorter overall survival in RCC patients. In TCGA RCC RNA-sequencing dataset, C-X-C chemokine receptor type 4 (CXCR4), a prognostic and stemness-related factor in RCC, is a gene whose expression is substantially correlated with NRN1 expression. Gain- and loss-of-function studies in RCC-PDC spheroid cultures revealed that NRN1 significantly promotes cell viability along with the upregulation of CXCR4. The NRN1-specific siRNA injection significantly suppressed the proliferation of RCC-PDC-derived xenograft tumors, in which CXCR4 expression is significantly repressed. CONCLUSION: NRN1 can be a potential diagnostic and therapeutic target in RCC as analyzed by preclinical patient-derived cancer models and clinicopathological studies.

前立腺癌のホルモン療法中のサロゲートマーカーの開発を目的に、アンドロゲン受容体の影響を受けない分子を探索した。前立腺癌細胞株(LNCaP)とCRPC細胞株(C4-2)を通常培養液およびアンドロゲン除去(去勢)環境下に継代を重ね、それぞれより抽出したRNAを対象にRNAseq解析を行った。21分子の中から特に発現が多く、前立腺癌の進行で発現量の増加が指摘されているLCN2に着目した。LCN2を発現する細胞集団は去勢環境下での継代につれて増大していた。さらに、抗LCN2抗体と各種レクチンを用いた共染色を細胞、前立腺癌組織を対象に行い共焦点レーザー顕微鏡で解析した。その結果、細胞レベルでのLCN2とLacDiNAcの発現が同じであることを確認した。この結果を踏まえ、抗LCN2抗体とWJA(Wisteria japonica agglutinin)を用いて、前立腺癌の産生するLCN2を特異的に検出できる「LCN2-WJAアッセイ」の確立と最適化を行い、改めてWJA/LCNが去勢抵抗性前立腺癌のマーカーと成りうることが示された。

Primary prostate cancer (PC) progresses to castration-resistant PC (CRPC) under androgen deprivation therapy, by mechanisms e.g. expression of androgen receptor (AR) splice variant-7 (AR-V7). Here we conducted comprehensive epigenome and transcriptome analyses comparing LNCaP, primary PC cells, and LNCaP95, AR-V7-expressing CRPC cells derived from LNCaP. Of 399 AR-V7 target regions identified through ChIP-seq analysis, 377 could be commonly targeted by hormone-stimulated AR, and 22 were specifically targeted by AR-V7. Among genes neighboring to these AR-V7 target regions, 78 genes were highly expressed in LNCaP95, while AR-V7 knockdown led to significant repression of these genes and suppression of growth of LNCaP95. Of the 78 AR-V7 target genes, 74 were common AR/AR-V7 target genes and 4 were specific AR-V7 target genes; their most suppressed genes by AR-V7 knockdown were NUP210 and SLC3A2, respectively, and underwent subsequent analyses. NUP210 and SLC3A2 were significantly upregulated in clinical CRPC tissues, and their knockdown resulted in significant suppression of cellular growth of LNCaP95 through apoptosis and growth arrest. Collectively, AR-V7 contributes to CRPC proliferation by activating both common AR/AR-V7 target and specific AR-V7 target, e.g. NUP210 and SLC3A2.

Cystinuria is an inherited disease, and the defective reabsorption of cysteine causes often requires operations for large urinary stones from childhood. It is rare to be diagnosed only with bladder stones and essential to select an operative procedure according to the age of the patient and the size of the stone. We report the case of a 2-year-old boy with cystinuria diagnosed with a large bladder stone and investigate the efficacy of transurethral cystolithotripsy assisted by percutaneous evacuation. Additional genetic analysis for the entire family revealed benefit for the life-span treatment of cystinuria.

We previously found that both the guide and passenger strands of the miR-139 duplex (miR-139-5p and miR-139-3p, respectively) were downregulated in cancer tissues. Analysis of TCGA datasets revealed that low expression of miR-139-5p (p < 0.0001) and miR-139-3p (p < 0.0001) was closely associated with 5-year survival rates of patients with renal cell carcinoma (RCC). Ectopic expression assays showed that miR-139-5p and miR-139-3p acted as tumor-suppressive miRNAs in RCC cells. Here, 19 and 22 genes were identified as putative targets of miR-139-5p and miR-139-3p in RCC cells, respectively. Among these genes, high expression of PLXDC1, TET3, PXN, ARHGEF19, ELK1, DCBLD1, IKBKB, and CSF1 significantly predicted shorter survival in RCC patients according to TCGA analyses (p < 0.05). Importantly, the expression levels of four of these genes, PXN, ARHGEF19, ELK1, and IKBKB, were independent prognostic factors for patient survival (p < 0.05). We focused on PXN (paxillin) and investigated its potential oncogenic role in RCC cells. PXN knockdown significantly inhibited cancer cell migration and invasion, possibly by regulating epithelial-mesenchymal transition. Involvement of the miR-139-3p passenger strand in RCC molecular pathogenesis is a new concept. Analyses of tumor-suppressive-miRNA-mediated molecular networks provide important insights into the molecular pathogenesis of RCC.

BACKGROUND: Patients with favorable-risk prostate cancer on active surveillance (AS) are strictly followed for safer execution. Repeat protocol biopsy is essential for evaluating cancer aggressiveness. However, the acceptance rate of repeat biopsy is not high enough because of the burdens of biopsy. We assessed the impact of complications after the initial biopsy on repeat protocol biopsy at 1 year using data from the Prostate Cancer Research International: Active Surveillance (PRIAS)-JAPAN study. METHODS: We performed a retrospective analysis using a prospective cohort in the PRIAS-JAPAN study. Patients with favorable-risk prostate cancer (n = 856) who consented to participate in the PRIAS-JAPAN study from 2010 to 2018 were enrolled. Follow-up evaluations included regular prostate-specific antigen, digital rectal examination and biopsy. Rates of complications after biopsies and repeat protocol biopsy non-acceptance rate at 1 year were reported. Logistic regression analysis explored the association between the complications after the initial biopsy and repeat protocol biopsy non-acceptance. RESULTS: Altogether, 759 patients (88.7%) actually proceeded to protocol at 1 year. Repeat protocol biopsy non-acceptance rate at 1 year was 14.9%. Regarding complications after the initial biopsy, hematuria (p = 0.028) and pain (p < 0.001) rates were significantly higher in the repeat biopsy non-acceptance group, but infection (p = 0.056) and hematospermia (p = 0.337) rates were not different. On multivariate logistic regression analysis, pain was a significant predictor for repeat protocol biopsy non-acceptance (odds ratio 4.68, 95% confidence interval 1.864-11.75; p = 0.001). CONCLUSIONS: Pain at the initial biopsy negatively impacts patients' compliance with further protocol biopsies during AS.

OBJECTIVES: To evaluate the relationship between residual urine volume, pyuria and bladder carcinoma recurrence. METHODS: The clinical data of 305 patients who had post-void residual urine volume measured and preoperative pyuria were retrospectively collected. The patients were classified into three risk groups based on the presence of residual urine and pyuria: good (negative residual urine and pyuria), intermediate (positive residual urine or pyuria) and poor (positive residual urine and pyuria). Predictive factors for intravesical recurrence-free survival were statistically analyzed using Cox proportional hazard models and Kaplan-Meier methods. The propensity score matching method was used to adjust the patients' backgrounds. RESULTS: The median follow-up period for all patients was 44 months. The presence of residual urine (P = 0.0164) and pyuria (P = 0.0233) were two independent prognostic factors for recurrence. After patients were classified into risk groups, the poor-risk group showed significantly shorter recurrence-free survival compared with that of the good- (P = 0.0002) and intermediate-risk groups (P = 0.0090). Even after matching, the presence of residual urine was related to short recurrence-free survival in male patients (P = 0.0012). When stratified by European Organization for Research and Treatment of Cancer risk groups, the presence of pyuria was related to short recurrence-free survival, especially for intermediate-risk patients without bacillus Calmette-Guérin treatment. CONCLUSIONS: Post-void residual urine and preoperative pyuria are two risks for recurrence-free survival in non-muscle-invasive bladder cancer.

Testicular germ cell tumor (GCT) is the most common type of malignancy in young males. Patients with nonseminomatous GCT still have poor prognosis. To identify new therapeutic targets, we generated patient-derived cells (PDCs) and their xenograft (PDCX) models from 3 distinct GCT patients' specimens. The pathological features of GCT PDCs and PDCX tumors recapitulated those of nonseminomatous components exhibiting in the corresponding patients' specimens. Notably, stemness-related markers and hypoxia-related genes, including hypoxia inducible factor 1α (HIF1A) and neuritin 1 (NRN1), were abundantly expressed in three-dimensional spheroid cultures of GCT PDCs. We identified functional HIF1α response elements in the NRN1 promoter and defined that their transcriptional activities were substantially activated by hypoxia. HIF1α inhibition by siRNAs or an inhibitor, 2-methoxyestradiol, significantly suppressed NRN1 expression and decreased the in vitro and in vivo growth of PDC spheroids. Moreover, NRN1 knockdown efficiently suppressed PDC proliferation. These results suggest that HIF1α and NRN1 are potential diagnostic and therapeutic targets, and that 2-methoxyestradiol could be applied to clinical management of GCT. Overall, our GCT PDC and PDCX models would be useful as preclinical models for precision medicine targeting each patient.

Extracellular vesicles (EVs) are lipid membranous vesicles that are released from every type of cell. It has become clear that EVs are involved in a variety of biological phenomena, including cancer progression, and play critical roles in intracellular communication through the horizontal transfer of cellular cargoes such as proteins, DNA fragments, RNAs including mRNA and non-coding RNAs (microRNA, piRNA, and long non-coding RNA) and lipids. The most common cause of death associated with cancer is metastasis. Recent investigations have revealed that EVs are deeply associated with metastasis. Bone is a preferred site of metastasis, and bone metastasis is generally incurable and dramatically affects patient quality of life. Bone metastasis can cause devastating complications, including hypercalcemia, pathological fractures, spinal compression, and bone pain, which result in a poor prognosis. Although the mechanisms underlying bone metastasis have yet to be fully elucidated, increasing evidence suggests that EVs in the bone microenvironment significantly contribute to cancer progression and cancer bone tropism. Emerging evidence on EV functions in bone metastasis will facilitate the discovery of novel treatments. In this review, we will discuss the remarkable effects of EVs, especially on the tumor microenvironment in bone.

BACKGROUND: Oligometastatic cancer has been suggested as an intermediate state between localized disease and wide-ranging metastases. The clinical significance of local treatment in oligometastatic prostate cancer (PCa) has been a recent topic of interest. However, standard definitions of oligometastasis are lacking. Here we studied risk factors among Japanese de novo oligometastatic patients with PCa. METHODS: We retrospectively assessed clinical data from 264 patients, including locally advanced (T3 or T4N0M0) cancer, lymph-node-positive cancer (Tany N1M0), and cancer with ≤10 bone metastases. All patients received androgen deprivation therapy only. The number of bone metastases and clinical factors were evaluated in association with overall survival (OS) and progression-free survival (PFS). The Mann-Whitney U test, Cox proportional hazard models, and Kaplan-Meier methods were used as statistical analyses. RESULTS: Median age, PSA at baseline and OS were 74 years, 55.2 ng/mL, and 129.0 months, respectively. The cutoff for the number of bone metastases having the greatest impact on OS was ≥3 (hazard ratio [HR]: 2.67; P = .0001). In multivariate analysis, non-regional lymph node (LN) metastases (HR: 2.15; P = .0222), ISUP grade group (GG) 5 (HR: 2.04; P = .0186) and ≥3 bone metastases (HR: 1.82; P = .0390) were independent predictors of OS. In risk classification based on these factors, OS and PFS were significantly classifiable into poor (2-3 factors), intermediate (1 factor), and good (no factors) risk groups (P < .0001). CONCLUSION: Not only the number of bone metastases, but also non-regional LN metastases predict OS in patients with de novo oligometastatic PCa.