title: Elevated collagen-I augments tumor progressive signals, intravasation and metastasis of prolactin-induced estrogen receptor alpha positive mammary tumor cells.
abstract: The development and progression of estrogen receptor alpha positive (ERα+) breast cancer has been linked epidemiologically to prolactin. However, activation of the canonical mediator of prolactin, STAT5, is associated with more differentiated cancers and better prognoses. We have reported that density/stiffness of the extracellular matrix potently modulates the repertoire of prolactin signals in human ERα + breast cancer cells in vitro: stiff matrices shift the balance from the Janus kinase (JAK)2/STAT5 cascade toward pro-tumor progressive extracellular regulated kinase (ERK)1/2 signals, driving invasion. However, the consequences for behavior of ERα + cancers in vivo are not known.
  
  
  
  In order to investigate the importance of matrix density/stiffness in progression of ERα + cancers, we examined tumor development and progression following orthotopic transplantation of two clonal green fluorescent protein (GFP) + ERα + tumor cell lines derived from prolactin-induced tumors to 8-week-old wild-type FVB/N (WT) or collagen-dense (col1a1tm1Jae/+) female mice. The latter express a mutant non-cleavable allele of collagen 1a1 "knocked-in" to the col1a1 gene locus, permitting COL1A1 accumulation. We evaluated the effect of the collagen environment on tumor progression by examining circulating tumor cells and lung metastases, activated signaling pathways by immunohistochemistry analysis and immunoblotting, and collagen structure by second harmonic generation microscopy.
  
  
  
  ERα + primary tumors did not differ in growth rate, histologic type, ERα, or prolactin receptor (PRLR) expression between col1a1tm1Jae/+and WT recipients. However, the col1a1tm1Jae/+environment significantly increased circulating tumor cells and the number and size of lung metastases at end stage. Tumors in col1a1tm1Jae/+recipients displayed reduced STAT5 activation, and higher phosphorylation of ERK1/2 and AKT. Moreover, intratumoral collagen fibers in col1a1tm1Jae/+recipients were aligned with tumor projections into the adjacent fat pad, perpendicular to the bulk of the tumor, in contrast to the collagen fibers wrapped around the more uniformly expansive tumors in WT recipients.
  
  
  
  A collagen-dense extracellular matrix can potently interact with hormonal signals to drive metastasis of ERα + breast cancers.
authors.affiliation: Cellular and Molecular Biology Program, University of Wisconsin-Madison, Madison, WI, USA.|Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Craig E
authors.initials: CE
authors.lastname: Barcus
authors.affiliation: Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: O'Leary
authors.affiliation: Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Brockman
authors.affiliation: Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Debra E
authors.initials: DE
authors.lastname: Rugowski
authors.affiliation: Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Garcia
authors.affiliation: Department of Biostatistics & Medical Informatics, University of Wisconsin-Madison, Madison, WI, USA.|University of Wisconsin Paul P. Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Wisconsin, USA.
authors.forename: Menggang
authors.initials: M
authors.lastname: Yu
authors.affiliation: Cellular and Molecular Biology Program, University of Wisconsin-Madison, Madison, WI, USA.|Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, USA.|Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, WI, USA.|University of Wisconsin Paul P. Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Wisconsin, USA.
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Keely
authors.affiliation: Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, WI, USA.|University of Wisconsin Paul P. Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Wisconsin, USA.
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Eliceiri
authors.affiliation: Cellular and Molecular Biology Program, University of Wisconsin-Madison, Madison, WI, USA. linda.schuler@wisc.edu.|Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA. linda.schuler@wisc.edu.|University of Wisconsin Paul P. Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Wisconsin, USA. linda.schuler@wisc.edu.
authors.forename: Linda A
authors.initials: LA
authors.lastname: Schuler
mesh_terms: D000818:Animals; D015415:Biomarkers; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism*; D018450:Disease Progression; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D020935:MAP Kinase Signaling System; D051379:Mice; D008822:Mice, Transgenic; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating; D011388:Prolactin / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D047368:Tumor Burden
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D047628:Estrogen Receptor alpha; D050799:STAT5 Transcription Factor; D011388:Prolactin; D051057:Proto-Oncogene Proteins c-akt
keywords: Breast cancer; Collagen; Desmoplasia; Extracellular matrix; Prolactin; Tumor microenvironment; Tumor progression