Expression of alpha 2 type I collagen in W8 cells increases cell adhesion and decreases colony formation in soft agar

A chemically transformed cell line, W8, produces alpha 1(I) homotrimers with no alpha 2(I) chains whereas the parent cell line, K16, produces heterotrimers. When W8 cells were transfected with plasmid constructs containing the full length human alpha 2(I) cDNA driven by viral promoters, the cells expressed alpha 2(I) collagen chains forming varying amounts of heterotrimers. Previously, we have shown that K16 and W8 cells have different growth characteristics (Smith, B.D. et al., Cancer Research 43: 4275-4282, 1983) including population doubling, saturation density, cell adhesion and colony formation in soft agar. These parameters were tested for each transfected cell line in order to determine if the alpha 2(I) expression and heterotrimer formation alters cell characteristics. The cells expressing alpha 2(I) forming heterotrimers needed higher concentrations of trypsin or longer time periods to lift from the plate suggesting a role for alpha 2(I) in cell adhesion. The W8 cells formed colonies in soft agar exhibiting anchorage independent growth. However, W8 cells expressing alpha 2(I) chains formed less colonies in soft agar than W8 cells or W8 cells transfected with a neomycin resistant gene indicating that the alpha 2(I) producing cells were less anchorage independent than W8 cells. Population doubling time, morphology and saturation densities were similar to W8 cells with small alterations towards an epithelial morphology. These results demonstrated that alpha 2(I) within heterotrimer is important for cell adhesion and anchorage independent growth.