Collagen gel contraction serves to rapidly distinguish epithelial- and mesenchymal-derived cells irrespective of alpha-smooth muscle actin expression.
Mesenchymal-like cells in the stroma of breast cancer may arise as a consequence of plasticity within the epithelial compartment, also referred to as epithelial-mesenchymal transition, or by recruitment of genuine mesenchymal cells from the peritumoral stroma. Cells of both the epithelial compartment and the stromal compartment express alpha smooth muscle actin (alpha-sm actin) as part of a myoepithelial or a myofibroblastic differentiation program, respectively. Moreover, because both epithelial- and mesenchymal-derived cells are nontumorigenic, other means of discrimination are warranted. Here, we describe the contraction of hydrated collagen gels as a rapid functional assay for the distinction between epithelial- and mesenchymal-derived stromal-like cells irrespective of the status of alpha-sm actin expression. Three epithelial-derived cell lines and three genuine mesenchymal-derived breast cell lines were plated on top of hydrated collagen lattices. Reduction in gel height was measured every hour for 6 h and after 22 h using an x-y-z automated position table. Significantly, the epithelial-derived cells, irrespective of a high alpha-sm actin expression, had a fivefold lower contractility (10.0% reduction in gel height) than their true mesenchymal counterparts (53.1% reduction in gel height). To test whether at all force generation could be induced in the nonmesenchymal cells by alpha-sm actin, transductions were performed to obtain a tetracycline-dependent expression. Expression under these conditions did not augment contractility. It is concluded that epithelial-derived mesenchymal-like cells are functionally defective within a connective tissue environment irrespective of an apparent contractile phenotype.
Nielsen
Helga Lind
HL
Structural Cell Biology Unit, Institute of Medical Anatomy, The Panum Institute, Copenhagen, Denmark.
Gudjonsson
Thorarinn
T
Villadsen
René
R
Rønnov-Jessen
Lone
L
Petersen
Ole William
OW
D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001943:Breast Neoplasms; D018929:Cell Culture Techniques / Q000379:methods*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism*; D004318:Doxycycline / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D005260:Female; D005782:Gels; D006801:Humans; D008648:Mesoderm / Q000166:cytology* / Q000378:metabolism; D013314:Stress, Mechanical; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism
D000199:Actins; D000900:Anti-Bacterial Agents; D005782:Gels; D003094:Collagen; D004318:Doxycycline