Validation of a model of colon cancer progression

A unique feature of SW480 and SW620 colon carcinoma cell lines is that they are derived from primary and secondary tumours resected from a single patient. As such, they may represent a valuable resource for examining genetic changes late in colon cancer progression. In order to verify this, both cell lines have been characterized to determine whether phenotypic differences have been retained despite long-term cell culture in vitro. The primary tumour-derived SW480 cells have an epithelioid morphology in vitro, while metastasis-derived SW620 cells have a fibroblast-like appearance. Xenografts of SW480 cells form gland-like structures in vivo, while SW620 xenografts form solid sheets of tumour cells. SW620 cells have a higher BrdU labelling index than SW480 cells, and are more highly tumourigenic and metastatic. Furthermore, SW620 cells show less susceptibility to apoptosis induction by TNFalpha and anti-Fas monoclonal. Findings from these investigations therefore indicate that SW480 and SW620 cell lines do show appropriate phenotypic differences and represent an interesting model for studying the genetic events in the late stages of colon cancer progression.