title: Tumor dormancy: elevated expression of stanniocalcins in late relapsing breast cancer.
abstract: BACKGROUND
  Breast cancer is known for its propensity to recur even after decades. The biology behind this phenomenon of tumor dormancy is poorly understood. The stanniocalcins (stanniocalcin-1, STC-1 and stanniocalcin-2, STC-2) are 56kDa homodimeric proteins. They act as pro-survival factors and contribute to the endurance of terminally differentiated cells such as neurons and adipocytes. We investigated whether elevated expression of stanniocalcins also plays a part in the tumor dormancy of breast cancer.
  
  
  METHODS
  The expression of STC-1, STC-2 and estrogen receptor (ER) was studied by immunohistochemistry in 72 primary breast cancers and in their metastatic relapses detected before two years, or after 5 or 10 years from primary surgery.
  
  
  RESULTS
  When compared to primary tumors with early relapse and their metastases, the expression of STC-1 and STC-2 was significantly higher in relapses occurring after five year (STC-1 p=0.0012, STC-2 p=0.004) and even higher in very late relapses occurring 10 years after surgery (STC-1 p=0.0017, STC-2 p=0.0001). Moreover, primary tumors with a propensity of very late relapse displayed a higher initial expression of STC-2 (p=0.0001). A significantly increased frequency of ER expression was found in the very late relapses.
  
  
  CONCLUSIONS
  These findings suggest that elevated expression of STC-1 or STC-2 act as survival factors also for breast cancer cells and thereby contribute to tumor dormancy.
authors: Department of Pathology, University of Helsinki and HUSLAB, Helsinki University Central Hospital, P.O. Box 21, Haartmaninkatu 3, FI-00290 Helsinki, Finland.
authors: Kristiina
authors: K
authors: Joensuu
authors: Päivi
authors: P
authors: Heikkilä
authors: Leif C
authors: LC
authors: Andersson
mesh_terms: D014408:Biomarkers, Tumor / Q000096:biosynthesis; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006023:Glycoproteins / Q000096:biosynthesis*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011960:Receptors, Estrogen / Q000096:biosynthesis; D013997:Time Factors
chemical_list: D014408:Biomarkers, Tumor; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D011960:Receptors, Estrogen; C114997:STC2 protein, human; C051795:teleocalcin