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Featured researches published by Eitetsu Koh.


Cancer Research | 2004

The Adrenal Androgen Androstenediol Is Present in Prostate Cancer Tissue after Androgen Deprivation Therapy and Activates Mutated Androgen Receptor

Atsushi Mizokami; Eitetsu Koh; Hiroshi Fujita; Yuji Maeda; Masayuki Egawa; Kiyoshi Koshida; Seijiro Honma; Evan T. Keller; Mikio Namiki

Despite an initial response to androgen deprivation therapy, prostate cancer (PCa) progresses eventually from an androgen-dependent to an androgen-independent phenotype. One of the mechanisms of relapse is antiandrogen withdrawal phenomenon caused by mutation of 877th amino acid of androgen receptor (AR). In the present study, we established a method to measure the concentration of androstenediol (adiol) in prostate tissue. We found that adiol maintains a high concentration in PCa tissue even after androgen deprivation therapy. Furthermore, adiol is a stronger activator of mutant AR in LNCaP PCa cells and induces more cell proliferation, prostate-specific antigen (PSA) mRNA expression, and PSA promoter than dihydrotestosterone (DHT). Because antiandrogen, bicalutamide, blocked adiol activity in LNCaP cells, it was suggested that adiol effect was mediated through AR. However, high concentration of bicalutamide was necessary to block completely adiol activity. These effects were specific to LNCaP cells because adiol had less effect in PC-3 PCa cells transfected with wild-type AR than DHT and had similar effect in PC-3 cells transfected with mutant AR. The mechanism that adiol activates mutant AR in LNCaP cells did not result from the increased affinity to mutant AR or from AR’s association with coactivator ARA70. However, low concentration of adiol induced more AR nuclear translocation than DHT in LNCaP cells and not PC-3 cells transfected with AR. These results indicate that adiol may cause the progression of PCa even after hormone therapy.


Journal of Human Genetics | 1999

Spermatogenic ability is different among males in different Y chromosome lineage

Yoko Kuroki; Teruaki Iwamoto; Juwon Lee; Miki Yoshiike; Shiari Nozawa; Takayasu Nishida; Ashraf A. Ewis; Hideki Nakamura; Tatsushi Toda; Katsushi Tokunaga; Svetlana E Kotliarova; Kondoh N; Eitetsu Koh; Mikio Namiki; Toshikatsu Shinka; Yutaka Nakahori

AbstractIt is a controversial question whether sperm concentrations in humans are changing. Several researchers have reported on environmental factors affecting sperm quality, but the influence of genetic factors is still not fully understood. In this study, we examined the relationship between Y chromosome haplotypes and sperm concentration in fertile males. In addition, we determined the haplotypes of azoospermic patients. The results show that the mean sperm concentration correlates with Y chromosome type. Moreover, the occurrence of azoospermia is related to one particular Y chromosome lineage. Thus, males with a certain haplotype are at a disadvantage for fathering children. The difference of spermatogenic ability among men is important not only in pursuing male competition as in the past but also as relates to the future of modern human males.


The Aging Male | 2011

Androgen replacement therapy contributes to improving lower urinary tract symptoms in patients with hypogonadism and benign prostate hypertrophy: a randomised controlled study.

Kazuyoshi Shigehara; Kazuhiro Sugimoto; Hiroyuki Konaka; Masashi Iijima; Masato Fukushima; Yuji Maeda; Atsushi Mizokami; Eitetsu Koh; Hideki Origasa; Teruaki Iwamoto; Mikio Namiki

Purpose. We performed a randomised controlled study regarding the effects of androgen replacement therapy (ART) on lower urinary tract symptoms (LUTS) in hypogonadal men with benign prostate hypertrophy (BPH). Methods. Fifty-two patients with hypogonadism and BPH were randomly assigned to receive testosterone (ART group) as 250 mg of testosterone enanthate every 4 weeks or to the untreated control group. We compared International Prostate Symptom Score (IPSS), uroflowmetry data, post-voiding residual volume (PVR) and systemic muscle volume at baseline and 12 months after treatment. Results. Forty-six patients (ART group, n = 23; control, n = 23) were included in the analysis. At the 12-month visit, IPSS showed a significant decrease compared with baseline in the ART group (15.7 ± 8.7 vs. 12.5 ± 9.5; p < 0.05). No significant changes were observed in the control group. The ART group also showed improvement in maximum flow rate and voided volume (p < 0.05), whereas no significant improvements were observed in the controls. PVR showed no significant changes in either group. In addition, the ART group showed significant enhancement of mean muscle volume (p < 0.05), whereas no significant changes were seen in the controls. Conclusion. ART improved LUTS in hypogonadal men with mild BPH.


Journal of Chromatography B | 2009

Simultaneous determination of salivary testosterone and dehydroepiandrosterone using LC–MS/MS: Method development and evaluation of applicability for diagnosis and medication for late-onset hypogonadism

Yujin Shibayama; Tatsuya Higashi; Kazutake Shimada; Akira Odani; Atsushi Mizokami; Hiroyuki Konaka; Eitetsu Koh; Mikio Namiki

Late-onset hypogonadism (LOH) is a male-specific disorder caused by the age-related decline in androgens, such as testosterone (T). A sensitive liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method for the simultaneous quantification of T and its precursor, dehydroepiandrosterone (DHEA), in human saliva has been developed and validated. The saliva was deprotenized with acetonitrile, purified using a Strata-X cartridge, derivatized with 2-hydrazino-1-methylpyridine, and subjected to LC-MS/MS. The recovery rates of the steroids during the pretreatment were about 90%. Quantification was based on selected reaction monitoring using characteristic transitions, and deuterated T and DHEA were used as internal standards. This method allowed the reproducible (inter- and intra-assay precisions, <2.9%) and accurate (accuracy, 98.5-101.8%) quantification of the salivary androgens using a 500-microl sample and the limits of quantification for both androgens were 10 pg/ml. As preliminary steps in the practical application of the developed method in diagnosis and medication for LOH, the diurnal rhythms, inter-day alternations and age differences in the salivary T and DHEA were examined; the method found that the salivary T and DHEA show specific diurnal rhythms, significant alternations in early morning and pronouncedly decline with age. The method also enabled the determination of the changes in the individual T and DHEA levels after the DHEA supplementation, which is expected to be a new and easy medication for LOH. Thus, the developed method has satisfactory applicability in the diagnosis and medication for LOH.


International Journal of Urology | 2008

Clinical Practice Manual for Late-onset Hypogonadism Syndrome

Mikio Namiki; Hideyuki Akaza; Toru Shimazui; Naoki Ito; Teruaki Iwamoto; Katsuyuki Baba; Hiroaki Kumano; Eitetsu Koh; Akira Tsujimura; Kiyomi Matsumiya; Shigeo Horie; Osamu Maruyama; Ken Marumo; Toshihiko Yanase; Yoshiaki Kumamoto

With the aging of the population, the quality of life (QOL) of middleaged and elderly men has come into question and it has been taken up from an interdisciplinary standpoint in recent years. Partial androgen deficiency of the aging male (PADAM) or lateonset hypogonadism (LOH) is a syndrome consisting of symptoms caused by partial deficiency of androgens, but the time of onset varies and the epidemiological status is unclear. Therefore, in Japan to date, this syndrome has been considered as a general phenomenon associated with aging, the medical authorities have not reacted and patients are not being treated. In Western countries however, this phenomenon has attracted attention in relation to geriatrics and reproductive endocrinology since the 1980s. In 1998, the International Society for the Study of the Aging Male (ISSAM) was founded to conduct basic and clinical research, to provide postgraduate education and to engage in publicity activities for the enlightenment of the public. The social background is characterized by the appearance of a very rapidly aging society with longer average life spans. The importance of improving the health of the elderly and preventive medicine as government policy has increased. Improving the health of the elderly not only promotes self-reliance of the elderly but also increases the work force. A high QOL is also possible. The main topic for healthcare in the 21st century is how to maintain the QOL of the elderly. In women, hormone replacement therapy (HRT) is widely applied internationally, but specific healthcare for elderly men appears to be limited to the widespread use of phosphodiesterase type 5 (PDE5) inhibitors to treat erectile dysfunction (ED). Although the delay in healthcare policies for elderly men is not a direct reason, a large gap has appeared between the average life spans of men and women in recent years and in Japan, men have a shorter life span than women by about seven years. In response to this sense of crisis, the World Health Organization (WHO) issued the Geneva Manifesto in 1997 and ‘healthy aging for men’ became an international movement. ISSAM was established in 1998 with the goal of ‘aging male research on gender specific issues in male health’. The first meeting of the society in Asia was held in Malaysia in 2001 and this topic was adopted on an international level from an early stage. The reason appeared to be strong economic and social concern that Asian countries with a current pyramid-type population distribution will become aging societies with a lower birth rate than in developing countries. Japan has already become an aging society with a low birth rate. In the national census (summary) in 2005, the elderly population of 65 years and older accounted for about 21% of the total population, the highest in the developed world. In Japan, scientific research on the aging male started at about the same time as in the rest of Asia, and the Japanese Society for the Study of the Aging Male (JSSAM) was founded in November 2001 with Yoshiaki Kumamoto, professor emeritus of Sapporo Medical University, and Hajime Nawata, professor of Kyushu University as representative facilitators. The goal of this society is ‘undertaking basic, clinical and social research and surveys on policies for the diagnosis, treatment and prevention of male-specific medical problems, and contributing widely to men’s health by development, promotion and spread of proper healthcare’. As mentioned above, the concept of research on the aging male is being promoted as ‘healthy aging for men’ but almost no actual treatment for such patients has been performed. When the JSSAM was established , so-called ‘male climacteric symptoms’ or ‘male menopause’ was popular in the media, and when such treatment was started , many patients mainly with a chief complaint of climacteric symptoms appeared in medical practice. These patients included many with psychiatric problems such as depression and considerable confusion arose in clinics and hospitals. Based on this background , the Subcommittee on Endocrinology, Reproductive Function and Sexual Function of the Japanese Urological Association asked the Scientific Committee to prepare a clinical practice guideline, and a working group was organized to prepare the guideline by a collaborative team from the Japanese Urological Association and JSSAM after a review by the Board of Directors. In this clinical practice manual, the term ‘late–onset hypogonadism (abbreviation: LOH)’ syndrome was adopted as the term that best expresses this condition medically. In order to recommend standard procedures for diagnosis, treatment, prevention and monitoring of adverse reactions due to androgen replacement therapy (ART) and post-treatment assessments, a literature survey of clinical papers was performed , but since treatment of LOH Syndrome has just started , almost all papers had a low recommendation rank. Therefore, the name was changed to ‘Clinical Practice Manual for Treatment of Late-onset Hypogonadism (LOH) Syndrome’ (‘Manual’ hereinafter) instead of the initially planned ‘clinical practice guideline’. Care of LOH Syndrome is in its initial stages and such treatment requires careful consideration. Since many men visiting medical institutions at present complain of ‘climacteric symptoms’, measures must be taken to have this disease recognized in the mental health field. In the future, it will be necessary to establish evidence for treatment of LOH Syndrome from the broad perspective of promotion of ‘healthy aging for men.’ This ‘Manual’ is the first edition aimed at gathering evidence through future diagnosis and treatment of LOH and it is hoped that it will serve as a reference for routine medical practice. Correspondence: Eitetsu Koh MD, Department of Urology, Kanazawa University School of Medicine, 13-1 Takaramachi, Kanazawa 920-8641, Japan. Email: [email protected] This is an English translation of text originally published in Japanese in (LOH ) , 2007, Jihou


Endocrine-related Cancer | 2009

Prostate cancer stromal cells and LNCaP cells coordinately activate the androgen receptor through synthesis of testosterone and dihydrotestosterone from dehydroepiandrosterone

Atsushi Mizokami; Eitetsu Koh; Kouji Izumi; Kazutaka Narimoto; Masashi Takeda; Seijiro Honma; Jinlu Dai; Evan T. Keller; Mikio Namiki

One of the mechanisms through which advanced prostate cancer (PCa) usually relapses after androgen deprivation therapy (ADT) is the adaptation to residual androgens in PCa tissue. It has been observed that androgen biosynthesis in PCa tissue plays an important role in this adaptation. In the present study, we investigated how stromal cells affect adrenal androgen dehydroepiandrosterone (DHEA) metabolism in androgen-sensitive PCa LNCaP cells. DHEA alone had little effect on prostate-specific antigen (PSA) promoter activity and the proliferation of LNCaP cells. However, the addition of prostate stromal cells or PCa-derived stromal cells (PCaSC) increased DHEA-induced PSA promoter activity via androgen receptor activation in the LNCaP cells. Moreover, PCaSC stimulated the proliferation of LNCaP cells under physiological concentrations of DHEA. Biosynthesis of testosterone or dihydrotestosterone from DHEA in stromal cells and LNCaP cells was involved in this stimulation of LNCaP cell proliferation. Androgen biosynthesis from DHEA depended upon the activity of various steroidogenic enzymes present in stromal cells. Finally, the dual 5alpha-reductase inhibitor dutasteride appears to function not only as a 5alpha-reductase inhibitor but also as a 3beta-hydroxysteroid dehydrogenase inhibitor in LNCaP cells. Taken together, this coculture assay system provides new insights of coordinate androgen biosynthesis under the microenvironment of PCa cells before and after ADT, and offers a model system for the identification of important steroidogenic enzymes involved in PCa progression and for the development of the corresponding inhibitors of androgen biosynthesis.


Materials Science and Engineering: C | 2000

Antiandrogenic Effect of Crude Extract of C-Heavy Oil

Ryoichi Kizu; Katsuaki Ishii; Jun Kobayashi; Takuma Hashimoto; Eitetsu Koh; Mikio Namiki; Kazuichi Hayakawa

Abstract An oil spill accident happened to a Russian tanker Nakhodka with a cargo of heavy oil type C in the Sea of Japan on January, 1997 and the spilled oil severely polluted the coast of Japan and damaged the environment. In this study, androgenic and antiandrogenic activities of C-heavy oil crude extracts prepared with ethanol were evaluated on two androgen-responsive cell lines, a Shionogi mouse mammary carcinoma SC115 and a human prostate carcinoma LNCaP. Oils used in this study were the Nakhodka and a commercial C-heavy oils. Assessment of androgenic and antiandrogenic activities was made on the basis of effect on proliferation (SC115) and prostate specific antigen (PSA) production (LNCaP cells) in the absence and the presence of 0.5 nM dihydrotestosterone (DHT). While both extracts exerted almost no effect on the proliferation and PSA production of SC115 and LNCaP cells in the absence of DHT, the extracts significantly inhibited the DHT-induced proliferation and PSA production of the cells in the presence of DHT, indicating that the C-heavy oils contains antiandrogenic compounds. It has been known that androgen receptor (AR) expressed in LNCaP cells has mutation in ligand-binding domain and consequently, its transcription promoting action after ligand-binding is different from that of normal AR. Cyproterone acetate (CA), an androgen antagonist, and 17β-estradiol, an estrogen, stimulated PSA production and their stimulatory effects were additive to that of DHT in LNCaP cells, while CA inhibited DHT-induced proliferation and 17β-estradiol showed quite weak agonistic effect in SC115 cells. Therefore, a part of antiandrogenic effects of the oil extracts was considered to be mediated through mechanism other than direct transcriptional activation by activated AR. Then, a few polycyclic aromatic hydrocarbons (PAHs) that are considered not to bind to AR were examined for their androgenic and antiandrogenic effect. Benzo[ a ]anthracene (BaA), benzo[ k ]fluoranthene (BkF) and benzo[ a ]pyrene (BaP) suppressed DHT-induced proliferation and PSA production of SC115 and LNCaP cells in a concentration-dependent manner. The antiandrogenic effect of the two heavy oil extracts was considered to be due in part to PAHs.


Cancer | 2011

Etiologic role of human papillomavirus infection in bladder carcinoma

Kazuyoshi Shigehara; Toshiyuki Sasagawa; Shohei Kawaguchi; Takao Nakashima; Masayoshi Shimamura; Yuji Maeda; Hiroyuki Konaka; Atsushi Mizokami; Eitetsu Koh; Mikio Namiki

The authors elucidated an etiologic role of human papillomavirus (HPV) infection in carcinoma of the bladder.


The Prostate | 2009

Tranilast inhibits hormone refractory prostate cancer cell proliferation and suppresses transforming growth factor β1-associated osteoblastic changes

Kouji Izumi; Atsushi Mizokami; You Qiang Li; Kazutaka Narimoto; Kazuhiro Sugimoto; Yoshifumi Kadono; Yasuhide Kitagawa; Hiroyuki Konaka; Eitetsu Koh; Evan T. Keller; Mikio Namiki

Tranilast is a therapeutic agent used in treatment of allergic diseases, although it has been reported to show anti‐tumor effects on some cancer cells. To elucidate the effects of tranilast on prostate cancer, we investigated the mechanisms of its anti‐tumor effect on prostate cancer.


Journal of Chromatography A | 2002

Identification of dehydroepiandrosterone metabolites formed from human prostate homogenate using liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry

Kuniko Mitamura; Nakagawa T; Kazutake Shimada; Mikio Namiki; Eitetsu Koh; Atsushi Mizokami; Seijiro Honma

The identification of the in vitro metabolites of dehydroepiandrosterone formed from human prostate homogenate was investigated by hyphenated techniques using the stable-isotope dilution method. A mixture of dehydroepiandrosterone and [2H4]dehydroepiandrosterone was incubated with hypertrophied human prostate tissue homogenate in the presence of NAD, NADH and NADPH. The metabolites were extracted with AcOEt-hexane, purified by solid-phase extraction, and then analyzed by LC-atmospheric pressure chemical ionization MS and/or GC-MS. Androst-5-ene-3beta,17beta-diol (major product), androst-4-ene-3,17-dione, testosterone, 5alpha-dihydrotestosterone, androsterone, and 7alpha-hydroxydehydroepiandrosterone were identified in comparison with authentic samples based on their chromatographic behavior and mass spectra.

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Teruaki Iwamoto

International University of Health and Welfare

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Kouji Izumi

University of Rochester Medical Center

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