Characterisation of breast cancer cell lines and establishment of a novel isogenic subclone to study migration, invasion and tumourigenicity

The process of tumour invasion and subsequent metastasis represents the most lethal aspect of cancer. In this study the invasive and migratory activity of four human breast cancer cell lines; MCF-7, MDA-MB-231, BT474 and Hs578T was investigated. Isogenic subclones were isolated from the Hs578T cell line using sequential passages through the BD Matrigel (TM) Invasion Chamber assay system. A new invasive subclone designated, Hs578Ts(i)(8) was isolated and shown to be 3-fold more invasive and 2.5-fold more migratory than the parental cell line. The variant cells formed up to 25 times more colonies in soft agar and also produced tumours in vivo in nude mice. Flow cytometry analysis showed that the Hs578Ts(i)(8) cells had 30% more CD44 (+)/CD24(-/low) cells than the parental Hs578T cell line. The presence of a breast cancer stem cell population within the variant cell line may provide an explanation for the increased anchorage independent growth and tumourigenicity.