title: Expression and Distribution of Calcium-Binding Protein S100P in Human Placenta during Pregnancy.
abstract: BACKGROUND
  S100P is a member of the S100 family of calcium-binding proteins, and it participates in pathophysiological events, such as tumor growth and invasion. Based on the striking similarities between trophoblast cells and tumor cells with regard to proliferative and invasive properties, we raised the question of whether and how S100P expresses in trophoblast cells during development. This study aimed to investigate the expression pattern of S100P in the human placenta during pregnancy development.
  
  
  METHODS
  In this experimental study, we collected 16 first-trimester placental tissues, 10 second-trimester placental tissues, and 12 term placentas. The mRNA expression levels of S100P were detected by reverse-transcription-polymerase chain reaction (RT-PCR) and quantitative real-time PCR, the protein expression levels were detected by western blot, and the localization of S100P was measured by immunohistochemical staining. The values obtained from PCR and western blot analysis were expressed as the mean ± SD. Levene's test was used to test equal variances, and one-way analysis of variance (ANOVA) was used to evaluate differences between groups.
  
  
  RESULTS
  Protein and mRNA expression of S100P could be detected in placenta during pregnancy, with minor higher levels in first-trimester (p>0.05). Immunohistochemical staining revealed that S100P protein was strongly expressed in syncytiotrophoblasts, and moderate expression was detected in villous cytotrophoblasts and cytotrophoblast columns. The S100P protein was localized to both cytoplasm and nuclei in syncytiotrophoblasts, while it only existed in the cytoplasm of cytotrophoblasts.
  
  
  CONCLUSIONS
  S100P was strongly detected in human placenta during pregnancy. The specific expression and distribution of S100P in human placenta throughout gestation suggested that S100P function might vary with its location in the placenta.
authors.affiliation: Assisted Reproduction Unit, Department of Obstetrics and Gynecology , Sir Run Run Show Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Zhu
authors.affiliation: Assisted Reproduction Unit, Department of Obstetrics and Gynecology , Sir Run Run Show Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Tong
authors.affiliation: Assisted Reproduction Unit, Department of Obstetrics and Gynecology , Sir Run Run Show Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Xiao-Na
authors.initials: XN
authors.lastname: Lin
authors.affiliation: Assisted Reproduction Unit, Department of Obstetrics and Gynecology , Sir Run Run Show Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Ling-Ying
authors.initials: LY
authors.lastname: Jiang
authors.affiliation: Assisted Reproduction Unit, Department of Obstetrics and Gynecology , Sir Run Run Show Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Jun-Xia
authors.initials: JX
authors.lastname: Wang
authors.affiliation: Assisted Reproduction Unit, Department of Obstetrics and Gynecology , Sir Run Run Show Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Song-Ying
authors.initials: SY
authors.lastname: Zhang
keywords: Placenta; Pregnancy; S100P; Trophoblast