Characterization of cell lines originating from an invasive transitional cell carcinoma

A reporter gene (lacZ) was introduced into a human transitional cell cancer cell line (Hu1703He) by means of liposomal transfection. The lacZ-transfected cell line induced subcutaneous tumours in nude rats and cells from one rat tumour were then established as a monolayer culture. The two lacZ-transfected cell lines both stained positive for CK7 and negative for CK14 and additionally formed spheroids in three-dimensional cultures. Insignificant genomic changes occurred in the tumour cells after incubation in nude rats, while the lacZ transfection caused alterations that probably correspond to increased invasiveness and tumourigenicity in vitro and in vivo. Most important is the observation that lacZ transfection of this human TCC cell line does not reduce its invasion potential in vitro or in vivo. The lacZ reporter gene may thus be exploited to facilitate the identification and quantification of migrating tumour cells and subsequently for studies of invasion in in vitro coculture systems. The observation that the spheroidal growth is reduced after transfection of the cell line, in contrast to increased invasion and cellular growth in monolayer, is an observation indicating that a three-dimensional arrangement mimicking the in vivo conditions offers important regulating factors to cellular growth.