Takeshi Namekawa

Lineage plasticity mediates resistance to androgen receptor pathway inhibitors (ARPIs) and progression from adenocarcinoma to neuroendocrine prostate cancer (NEPC), a highly aggressive and poorly understood subtype. Neuronal transcription factor ASCL1 has emerged as a central regulator of the lineage plasticity driving neuroendocrine differentiation. Here, we showed that ASCL1 was reprogrammed in ARPI-induced transition to terminal NEPC and identified that the ASCL1 binding pattern tailored the expression of lineage-determinant transcription factor combinations that underlie discrete terminal NEPC identity. Notably, we identified FOXA2 as a major cofactor of ASCL1 in terminal NEPC, which is highly expressed in ASCL1-driven NEPC. Mechanistically, FOXA2 and ASCL1 interacted and worked in concert to orchestrate terminal neuronal differentiation. We identified that prospero homeobox 1 was a target of ASCL1 and FOXA2. Targeting prospero homeobox 1 abrogated neuroendocrine characteristics and led to a decrease in cell proliferation in vitro and tumor growth in vivo. Our findings provide insights into the molecular conduit underlying the interplay between different lineage-determinant transcription factors to support the neuroendocrine identity and nominate prospero homeobox 1 as a potential target in ASCL1-high NEPC.

Tyrosine kinase inhibitors (TKIs) are used as targeted drugs for advanced renal cell carcinoma (RCC), although most cases eventually progress by acquiring resistance. Cancer stemness plays critical roles in tumor aggressiveness and therapeutic resistance, and dipeptidyl peptidase IV (DPP4) has been recently identified as a cancer stemness-related protein. A question arises whether DPP4 contributes to TKI efficacy in RCC. We established patient-derived RCC spheroids and showed that DPP4 expression is associated with stemness-related gene expression. TKI sunitinib resistance was rescued by DPP4 inhibition using sitagliptin or specific siRNAs in RCC cells and tumors. DPP4 expression can be inducible by retinoic acid and repressed by ALDH1A inhibition. Among type 2 diabetes patients with clinical RCC tumors, higher TKI efficacy is observed in those bearing DPP4^high tumors treated with DPP4 inhibitors. This study provides new insights into TKI resistance and drug repositioning of DPP4 inhibitor as a promising strategy for advanced RCC.

Various preclinical models have been developed to clarify the pathophysiology of prostate cancer (PCa). Traditional PCa cell lines from clinical metastatic lesions, as exemplified by DU-145, PC-3, and LNCaP cells, are useful tools to define mechanisms underlying tumorigenesis and drug resistance. Cell line-based experiments, however, have limitations for preclinical studies because those cells are basically adapted to 2-dimensional monolayer culture conditions, in which the majority of primary PCa cells cannot survive. Recent tissue engineering enables generation of PCa patient-derived xenografts (PDXs) from both primary and metastatic lesions. Compared with fresh PCa tissue transplantation in athymic mice, co-injection of PCa tissues with extracellular matrix in highly immunodeficient mice has remarkably improved the success rate of PDX generation. PDX models have advantages to appropriately recapitulate the molecular diversity, cellular heterogeneity, and histology of original patient tumors. In contrast to PDX models, patient-derived organoid and spheroid PCa models in 3-dimensional culture are more feasible tools for in vitro studies for retaining the characteristics of patient tumors. In this article, we review PCa preclinical model cell lines and their sublines, PDXs, and patient-derived organoid and spheroid models. These PCa models will be applied to the development of new strategies for cancer precision medicine.

Background: In the era of improving assisted reproductive technology (ART), patients with obstructive azoospermia (OA) have 2 options: vasal repair or testicular sperm extraction with intracytoplasmic sperm injection. Vasal repair, including vasovasostomy (VV) and vasoepididymostomy (VE), is the only option that leads to natural conception.Methods: This article reviews the surgical techniques, outcomes, and predictors of postoperative patency and pregnancy, with a focus on articles that have reported over the last 10 years, using PubMed database searches.Main findings: The reported mean patency rate was 87% and the mean pregnancy rate was 49% for a patient following microscopicVVand/orVEfor vasectomy reversal. Recently, robot‐assisted techniques were introduced and have achieved a high rate of success. The predictors and predictive models of postoperative patency and pregnancy also have been reported. The obstructive interval, presence of a granuloma, and intraoperative sperm findings predict postoperative patency. These factors also predict postoperative fertility. In addition, the female partner's age and the same female partner correlate with pregnancy after surgery.Conclusion: In the era ofART, the physician should present and discuss with both the patient withOAand his partner the most appropriate procedure to conceive by using these predictors.

Purpose: The aim of our study was to identify the clinical predictors of spermatogenesis recovery in testicular cancer (TC) patients after chemotherapy and to determine the recuperation period for spermatogenesis.Methods: Patients treated for TC from January 1982 to November 2001 at Chiba University Hospital were retrospectively assessed. Thirty‐five patients who met the following criteria were examined—(i) underwent both high orchiectomy and cisplatin‐based chemotherapy; (ii) had semen analyses and hormonal measurements; and (iii) were alive with no evidence of disease. Clinical variables associated with normalization of spermatogenesis after chemotherapy were examined. Time to recover normospermia was also evaluated using Kaplan–Meier analysis.Results: The observation period was 13.3 ± 5.6 years. Reappearance of sperm was confirmed in 85.7 % of patients, and 54.3 % of patients recovered normospermia. Age at diagnosis p = 0.0057), number of chemotherapy cycles p = 0.0042), and follicle‐stimulating hormone at the end of chemotherapy p = 0.0220) were independent factors related to post‐chemotherapy normalization of semen findings. The median (95 % CI) time to recover normospermia was 40 (range 22–96) months.Conclusions: These findings help to predict whether spermatogenesis will recover and its timing. They may also help clinicians identify and manage TC patients at a higher risk of prolonged azoospermia after chemotherapy.

To investigate the therapeutic outcomes of neoadjuvant and concurrent androgen-deprivation therapy and intensity-modulated radiation therapy with gold marker implantation for intermediate- and high-risk prostate cancer.This was a retrospective study of 325 patients with intermediate- or high-risk prostate cancer according to the National Comprehensive Cancer Network guidelines who underwent androgen-deprivation therapy and intensity-modulated radiation therapy (76 Gy) after gold marker implantation between 2001 and 2010.The 5-year distant metastasis-free survival rate was significantly lower for very high-risk patients than for intermediate- and high-risk patients (82.6% vs 99.4% and 96.5%, respectively; P < 0.01). The 5-year biochemical relapse-free survival rates significantly declined with increasing prostate cancer risk (P < 0.01), and were 95.9%, 87.2%, and 73.1% for the intermediate-risk, high-risk and very high-risk patients, respectively. Acute genitourinary and gastrointestinal toxicity grade ≥3 were not observed in any of the patients. Late grade 3 genitourinary toxicity occurred in 0.3% of patients.Combination androgen-deprivation therapy and 76-Gy intensity-modulated radiation therapy with gold marker implantation offers good therapeutic outcomes with few serious complications in patients with intermediate- and high-risk prostate cancer.