RESUMO
Variants from the HCT-8 colon-cancer cell line were implanted s.c. and orthotopically into nude mice. Well-differentiated HCT-8/E11 and HCT-8/E41 cells have a functional E-cadherin-catenin complex and are non-invasive into pre-cultured chick heart fragments in vitro, whereas poorly differentiated HCT-8/E11R1 cells are deficient in alpha-catenin protein and invasive in heart fragments. We investigated whether these differences were maintained in vivo. In contrast with in vitro observations, in vivo the 3 HCT-8 variants behaved very similarly and all formed undifferentiated tumors. The in vivo invasive behavior of HCT-8 cells was site-dependently modulated: HCT-8 cells invaded when injected into the cecum but not when injected s.c. Metastases to the liver or lungs were not observed. The composition and expression of the E-cadherin-catenin complex in nude mouse HCT-8 tumors was the same as in HCT-8 cells in culture on solid substrate. We conclude that the in vivo invasive behavior of HCT-8 cells is not determined by whether alpha-catenin is expressed or not but by as yet unidentified host factors.
