Mayuko Kanayama

Hyperactive mTOR induces neuroendocrine differentiation in prostate cancer cell with concurrent up-regulation of IRF1

Neuroendocrine‐differentiated prostate cancer (NEPCa) is refractory to androgen deprivation therapy and shows a poor prognosis. The underlying mechanisms responsible for neuroendocrine differentiation (NED) are yet to be clarified. In this study, we investigated the role of mammalian target of rapamycin (mTOR) in NEPCa.

Aryl hydrocarbon receptor signaling involved in the invasiveness of LNCaP cells

Abstract There is now mounting evidence that the aryl hydrocarbon receptor (AhR) plays an important role in physiologic responses such as development, cell cycle regulation, immune function and also malignant transformation in various tissues. The strong nuclear AhR expression is observed in the invasive phenotype, and an elevated nuclear AhR expression is associated with a poor prognosis of human prostate cancer. On the other hand, there are conflicting results that the AhR deficiency results in increased susceptibility to prostate tumors in mouse model. In the present study, we investigated AhR expression and its role in the growth and invasiveness of human prostate cancer cells. The AhR protein expression was detected in prostate cancer cell lines and human prostate cancer tissues. A small interfering RNA targeting AhR, constitutive active AhR expression vector, and AhR agonist and antagonist were used to moderate its expression and signaling. The induction of AhR signaling attenuated invasiveness of prostate cancer cells without affecting the cellular growth rate. These results suggest that AhR signaling in prostate cancer cells facilitates invasion of these cells, and modulation with this signaling can be a potential therapeutic target of invasive tumors.

Sarcopenia is a poor prognostic factor of castration-resistant prostate cancer treated with docetaxel therapy

Background Sarcopenia is a geriatric syndrome that is characterized by the gradual muscle loss and frailty in the elderly. Meanwhile, the prevalence of prostate cancer is on the rise worldwide. Mainstay treatments for metastatic prostate cancer are androgen-deprivation therapy and taxane-based chemotherapy. Owing to the indolent nature of prostate cancer, these treatments tend to be long-lasting, giving rise to the problem of tolerance to the treatments. Especially given the fact that long-term chemotherapy is closely associated with muscle loss, we aimed to elucidate the correlation between chemotherapy and sarcopenia in the clinical setting. Materials and methods This study was a retrospective study. Participants with castration-resistant prostate cancer were recruited from November 2009 to September 2015. Participants were recruited at two hospitals, Juntendo and Teikyo University Hospital, Tokyo, Japan. Participants were 77 Japanese males with castration-resistant prostate cancer who underwent docetaxel chemotherapy. Sarcopenia was defined as L3-psoas muscle index < 5.7 cm2/m2. We statistically investigated whether the existence of sarcopenia has an impact on the survival time, and identified potential covariates that affect it. Results Out of 77 patients, 26 patients (34%) were diagnosed as sarcopenia. Analysis showed that sarcopenia is independently associated with mortality risk (hazards ratio = 2.74, P = 0.0055). Sarcopenic patients showed significant decrease in body mass index, pretreatment hemoglobin, C-related protein, and L3-psoas muscle index as compared with nonsarcopenic patients. The median observation period was 499 days (330–790). Thirty-five patients (45%) died of prostate cancer during that period. Sarcopenic patients showed significantly shorter survival time after the initiation of docetaxel treatments (P = 0.0055). Conclusion Sarcopenia is an independent predictive factor for a poor tolerance to docetaxel treatment. Given that cessation of the treatment leads to death from the disease, our study identified sarcopenia as an independent factor that raises mortality risk.

The Surge in the Number of Circulating Tumor Cells Following Treatment with Sunitinib for Metastatic Renal Cell Carcinoma

Circulating tumor cells (CTCs) are a promising biomarker for several cancers. We streamlined the experimental procedure of CTC immunofluorescent staining. We encountered a 72-year-old woman with metastatic right renal cell carcinoma (RCC) (clinical stage: T4N0M1), whose CTC number rapidly increased after the administration of sunitinib and then gradually decreased. The change in the CTC number appeared to coincide with laboratory data and hypertension, suggesting that a CTC analysis may be useful for promptly monitoring the treatment response. Our data provided the first evidence of an association between the CTC numbers and the treatment response in a metastatic RCC patient.

Significant association between urethral length measured by magnetic resonance imaging and urinary continence recovery after robot-assisted radical prostatectomy

Introduction To determine the clinical predictive factors affecting the recovery from postoperative urinary incontinence after robot-assisted radical prostatectomy (RARP). Materials and methods We consecutively analyzed 320 patients who underwent RARP between January 2012 and March 2015. The restoration of urinary continence was defined as follows: the use of no pads/no leakage of urine or the use of a safety pad. Preoperative covariates were statistically assessed by multivariate logistic regression analysis to investigate their predict factor to recovery of urinary incontinence. Therefore, in this study, we sought to identify predictors of early urinary continence status in a single-center retrospective study of consecutive patients who underwent RARP. Results Continence rates at 1, 3, 6, and 12 months after the catheter was removed were 44%, 71%, 83%, and 93%, respectively. Age, body mass index, and prostate volume had no significant association with urinary continence recovery. In contrast to this, longer preoperative membranous urethral length (MUL) was significantly associated with earlier postoperative continence recovery. Multivariate analysis demonstrated that longer preoperative MUL is significantly associated with continence recovery at 1 month (P = 0.0235). Conclusion Approximately 70% of patients achieved urinary continence within 3 months after RARP. Multivariate analysis showed that age, body mass index, and prostate volume had no significant association with urinary continence recovery. Preoperative MUL assessed by magnetic resonance imaging was an independent predictor of early recovery from urinary incontinence after RARP.

Generation of transgenic mouse line with prostate-specific expression of codon-improved Cre recombinase

Background Genetically engineered mouse models are useful tools to decipher molecular mechanisms of diseases. As for prostates, a rat probasin promoter has been widely used to drive prostate-specific gene expression. To optimize its codon usage to that of mammals, we used codon-improved Cre recombinase (iCre) for prostate-specific Cre-loxP recombination. Materials and methods We generated transgenic mice that express iCre driven by conventional probasin promoter in a prostate-specific manner (PB-iCre). Linearized PB-iCre transgene deoxyribonucleic acids (DNAs) were microinjected into pronuclei of fertilized mouse embryos. The integration of the transgene was confirmed by Southern blot analysis. A line of transgenic mice expressing a sufficient amount of iCre mRNA in its prostate was selected. To test recombinase activity of PB-iCre in vivo, its offspring was crossbred with Ptenflox/flox mice in which murine prostate adenocarcinoma is reported to occur upon excision of loxP-flanked regions. Results Eight founder animals were obtained, all of which showed germ line integration of PB-iCre transgene by Southern blot analysis. Among them, the prostate from only one line (line 58) expressed a sufficient amount of iCre mRNA. This line was crossbred with Ptenflox/flox mice to generate PB-iCre58/Ptenflox/flox. As a result, 12-week-old PB-iCre58/Ptenflox/flox mice presented with prostate adenocarcinoma that was histologically similar to human cribriform prostate cancer of Gleason grade 4. Conclusions We have successfully established a transgenic mouse line that expresses iCre in a prostate-specific manner.

Diabetes and LOH Syndrome

Age-related declines in androgen levels lead to impaired organ function known as late-onset hypogonadism (LOH). Various diseases are considered to be involved in the emergence of LOH, among which are diabetes, metabolic syndrome, arteriosclerosis, hypertension, and hyperlipidemia. Testosterone increases insulin sensitivity in muscle through functional mitochondria in muscle tissue, while lowered testosterone conversely leads to reduced glucose uptake in muscle. Diabetes mellitus (DM) and LOH are deeply interrelated diseases requiring further clinical research results in areas including diagnosis and treatment.

Abstract A04: Hyperactive mTOR induces neuroendocrine differentiation in LNCaP prostate cancer cell with concurrent upregulation of interferon regulatory factor 1

The PI3K-Akt-mTOR pathway is frequently activated in prostate cancer. However, the precise function of mTOR in prostate cancer progression is yet to be elucidated. Thus, in this study, we performed a gain-of-function analysis by establishing human prostate cancer LNCaP stable line that expresses hyperactive mTOR (LNCaP-mTOR). Hyperactive mTOR induced neuroendocrine differentiation (NED) that can be suppressed by an mTOR inhibitor, rapamycin. Subsequent comprehensive mass spectrometric analysis in conjunction with cascade analysis indicates that the members of interferon regulator factor (IRF) family, especially IRF1, are key transcription factors in NED of LNCaP-mTOR. Aside from its major role in immune response, IRF1 is known to be a tumor suppressor. To further investigate the function of IRF1 in NED induced by hyperactive mTOR, we disrupted the IRF1 gene in LNCaP-mTOR by CRISPR/Cas system. The disruption of the IRF1 gene resulted in an acceleration of an NED-associated morphological change, elevation of neuroendocrine cell marker, neuron specific enolase, and a partial recovery of growth arrest. These results suggest that IRF1 partially suppresses NED at downstream of hyperactive mTOR. Together, our results indicate that two seemingly contradictory events, NED and the induction of IRF1, are induced by hyperactive mTOR, giving rise to a notion that pharmacological inhibition of mTOR can be a “double-edged sword” for prostate cancer treatments. Citation Format: Mayuko Kanayama, Toshiya Hayano, Tatsuya Maeda, Shigeo Horie, Atsu Aiba. Hyperactive mTOR induces neuroendocrine differentiation in LNCaP prostate cancer cell with concurrent upregulation of interferon regulatory factor 1. [abstract]. In: Proceedings of the Fourth AACR International Conference on Frontiers in Basic Cancer Research; 2015 Oct 23-26; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2016;76(3 Suppl):Abstract nr A04.