title: Cancer progression by breast tumors with Pit-1-overexpression is blocked by inhibition of metalloproteinase (MMP)-13.
abstract: BACKGROUND
  The POU class 1 homeobox 1 transcription factor (POU1F1, also known as Pit-1) is expressed in the mammary gland and its overexpression induces profound phenotypic changes in proteins involved in cell proliferation, apoptosis, and invasion. Patients with breast cancer and elevated expression of Pit-1 show a positive correlation with the occurrence of distant metastasis. In this study we evaluate the relationship between Pit-1 and two collagenases: matrix metalloproteinase-1 (MMP-1) and matrix metalloproteinase-13 (MMP-13), which have been related to metastasis in breast cancer.
  
  
  METHODS
  We began by transfecting the MCF-7 and MDA-MB-231 human breast adenocarcinoma cell lines with the Pit-1 overexpression vector (pRSV-hPit-1). Afterward, the mRNA, protein, and transcriptional regulation of both MMP-1 and MMP-13 were evaluated by real-time PCR, Western blot, chromatin immunoprecipitation (ChIP), and luciferase reporter assays. We also evaluated Pit-1 overexpression with MMP-1 and MMP-13 knockdown in a severe combined immunodeficiency (SCID) mouse tumor xenograft model. Finally, by immunohistochemistry we correlated Pit-1 with MMP-1 and MMP-13 protein expression in 110 human breast tumors samples.
  
  
  RESULTS
  Our data show that Pit-1 increases mRNA and protein of both MMP-1 and MMP-13 through direct transcriptional regulation. In SCID mice, knockdown of MMP-13 completely blocked lung metastasis in Pit-1-overexpressing MCF-7 cells injected into the mammary fat pad. In breast cancer patients, expression of Pit-1 was found to be positively correlated with the presence of both MMP-1 and MMP-13.
  
  
  CONCLUSIONS
  Our data indicates that Pit-1 regulates MMP-1 and MMP-13, and that inhibition of MMP-13 blocked invasiveness to lung in Pit-1-overexpressed breast cancer cells.
authors.affiliation: Department of Physiology- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), School of Medicine, University of Santiago de Compostela, Praza do Obradoiro, Santiago de Compostela, 15782, Spain. bautistax@hotmail.com.
authors.forename: Juan
authors.initials: J
authors.lastname: Sendon-Lago
authors.affiliation: Department of Physiology- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), School of Medicine, University of Santiago de Compostela, Praza do Obradoiro, Santiago de Compostela, 15782, Spain. samuel.seoane@usc.es.
authors.forename: Samuel
authors.initials: S
authors.lastname: Seoane
authors.affiliation: Unidad de Investigación, Fundacion Hospital de Jove, Avenida Eduardo Castro, Gijón, 33290, Spain. investigacion@hospitaldejove.com.
authors.forename: Noemi
authors.initials: N
authors.lastname: Eiro
authors.affiliation: Department of Physiology- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), School of Medicine, University of Santiago de Compostela, Praza do Obradoiro, Santiago de Compostela, 15782, Spain. maria.bermudez@usc.es.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Bermudez
authors.affiliation: Departments of Obstetrics and Gynecology, School of Medicine, University of Santiago de Compostela, Praza do Obradoiro, Santiago de Compostela, 15782, Spain. manuelmaciac@msn.com.
authors.forename: Manuel
authors.initials: M
authors.lastname: Macia
authors.affiliation: Departments of Morphological Sciences, School of Medicine, University of Santiago de Compostela, Praza do Obradoiro, Santiago de Compostela, 15782, Spain. tomas.garcia-caballero@usc.es.
authors.forename: Tomas
authors.initials: T
authors.lastname: Garcia-Caballero
authors.affiliation: Unidad de Investigación, Fundacion Hospital de Jove, Avenida Eduardo Castro, Gijón, 33290, Spain. franvizoso@gmail.com.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Vizoso
authors.affiliation: Department of Physiology- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), School of Medicine, University of Santiago de Compostela, Praza do Obradoiro, Santiago de Compostela, 15782, Spain. roman.perez.fernandez@usc.es.
authors.forename: Roman
authors.initials: R
authors.lastname: Perez-Fernandez
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000556:secondary; D000818:Animals; D017209:Apoptosis; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000556:secondary; D061986:MCF-7 Cells; D020781:Matrix Metalloproteinase 1 / Q000235:genetics* / Q000378:metabolism; D053509:Matrix Metalloproteinase 13 / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D012333:RNA, Messenger / Q000378:metabolism*; D050817:Transcription Factor Pit-1 / Q000235:genetics*
chemical_list: C494187:POU1F1 protein, human; D012333:RNA, Messenger; D050817:Transcription Factor Pit-1; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1