title: Bortezomib treatment causes long-term testicular dysfunction in young male mice.
abstract: BACKGROUND
  With increased long-term survivors of childhood cancer patients, therapy-associated infertility has become one of the most common late side-effects and significantly affects their life-quality. Therefore, evaluation of anti-cancer agents on male reproduction and infertility prevention are urgently demanding. The proteasome inhibitor bortezomib has been launched in clinical trials for childhood cancers, however, its potential side effects on reproduction have so far been neither investigated experimentally nor reported in treated children. Thus the present study is designed to explore the impact of bortezomib on male reproductive function and to gain insights into how bortezomib exerts its adverse effects on man gonad, thereby providing pediatric oncologists relevant information.
  
  
  METHODS
  35 day-old male mice were treated with one 11-day cycle of bortezomib and then sacrificed 2 days, 45 days, or 6 months later. A mating study was performed in the group followed for 6 months, and their pups were analyzed on postnatal day 50. Serum follicle-stimulating hormone (FSH) and testicular testosterone levels were measured. Testicular morphology was evaluated by light- and electron microscopy, and the underlying mechanisms and pathways of testis damage were investigated.
  
  
  RESULTS
  Testicular damage was visible already 2 days after stopping bortezomib and increased in severity by day 45. Then 80% of seminiferous tubules exhibited hypospermatogenesis with arrest at the levels of spermatogonia, spermatocytes and round spermatids. Germ cells were specifically targeted by bortezomib as evidenced by increased apoptosis mediated through activation of p53 and caspases. Even six months after the bortezomib treatment, testis weight, sperm concentration and seminiferous tubule length remained at a decreased level, indicating that spermatogenesis and tubular outgrowth could not fully recover. Combined with persistently increased serum levels of FSH in these mice, our results demonstrate that bortezomib can have long-term effects on testicular function, although fertility of bortezomib-exposed males remained and their offspring looked healthy.
  
  
  CONCLUSIONS
  Bortezomib treatment causes long-term gonadal dysfunction in male mice. Careful monitoring of gonadal function in male childhood cancer patients treated with bortezomib is thus strongly recommended.
authors.affiliation: Department of Women's and Children's Health, Astrid Lindgren Children's Hospital, Pediatric Endocrinology Unit Q2:08, Karolinska Institutet & University Hospital, SE-171 76 Stockholm, Sweden. Mi.Hou@ki.se.
authors.forename: Mi
authors.initials: M
authors.lastname: Hou
authors.forename: Emma
authors.initials: E
authors.lastname: Eriksson
authors.forename: Konstantin
authors.initials: K
authors.lastname: Svechnikov
authors.forename: Kirsi
authors.initials: K
authors.lastname: Jahnukainen
authors.forename: Olle
authors.initials: O
authors.lastname: Söder
authors.forename: Andreas
authors.initials: A
authors.lastname: Meinhardt
authors.forename: Lars
authors.initials: L
authors.lastname: Sävendahl
mesh_terms: D000818:Animals; D001897:Boronic Acids / Q000008:administration & dosage / Q000009:adverse effects*; D000069286:Bortezomib; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D008297:Male; D051379:Mice; D009369:Neoplasms / Q000150:complications / Q000188:drug therapy; D061988:Proteasome Inhibitors / Q000008:administration & dosage; D011719:Pyrazines / Q000008:administration & dosage / Q000009:adverse effects*; D013091:Spermatogenesis / Q000187:drug effects*; D013733:Testicular Diseases / Q000139:chemically induced / Q000473:pathology*; D013737:Testis / Q000187:drug effects / Q000473:pathology; D013739:Testosterone / Q000096:biosynthesis*
chemical_list: D001897:Boronic Acids; D061988:Proteasome Inhibitors; D011719:Pyrazines; D013739:Testosterone; D000069286:Bortezomib; D005640:Follicle Stimulating Hormone