Figure 1.

Lumen formation and restoration of in vivo polarity of primary cultures in ECM depends on the presence of serum or the growth factors EGF, TGF‐β1 and IGF‐1. (A) Phase‐contrast images of three primary colorectal cancer cultures cultured for 1 week as either serum‐free suspension cultures (upper panels) or embedded in Matrigel with added serum (lower panels). (B) F‐actin (red)/DAPI (blue) staining of colorectal cancer cultures from four patients cultured as a serum‐free suspension or in Matrigel with serum for 1 week. (C) F‐actin (red)/DAPI (blue) labelling of a C2284 primary culture grown as either a serum‐free suspension (left two panels) or in Matrigel with or without serum added. Phase image is included to demonstrate F‐actin‐lined lumen. (D) Effect of various serum growth factors on lumen formation in primary cultures cultured in Matrigel. C2284 primary serum‐free suspension cultures were embedded in Matrigel and the serum‐free medium was supplemented with either TGF‐1β (10 ng/ml), EGF (10 ng/ml) or IGF‐1 (1 μg/ml). Cetuximab anti‐EGFR monoclonal antibody was used at 20 μg/ml. Lumen formation was measured by F‐actin labelling. Ten per cent serum and no serum medium controls were used as positive and negative controls for lumens, respectively. At least 30 colonies were counted per condition (n = 3). Error bar = standard error of the mean. *p < 0.05 paired t‐test. Paired t‐test of 10% serum + cetuximab was not significantly different from the 10% serum control.