Figure 8

Functional relevance of MTAP expression in colon carcinoma. (a) Real-time PCR and Western blot analysis of the HT29M3 cell clones stably transfected with an MTAP expression plasmid. All cell clones (MTAP1, 2 and 3) showed strong expression of MTAP whereas MTAP expression in the mock-transfected cell clones (mock1 and 2) remained low. (b) Proliferation assays of the MTAP-expressing cell clones (HT29M3 MTAP1, 2 and 3) and the low MTAP-expressing cell clones (HT29M3 mock1 and 2) were performed under IFN treatment (100, 1000 and 10 000 U/ml). Growth of the untreated cells (mock1,2) was set as 100 per cent. As demonstrated before, in HT29M3 cells no significant reduction of HT29M3 mock1 and 2 proliferation by IFN-gamma treatment was observed whereas growth of the MTAP stable transfected cell clones was significantly suppressed (^*P<0.05; ^**P<0.01; NS: not significant). (c) Invasion assays (Boyden Chamber) of the cell clones revealed a strong invasive potential of the two analysed MTAP-expressing HT29M3 cell clones, MTAP1 and MTAP2, comparable to the colon carcinoma cell line HT29. In contrast, HT29M3 cells or mock-transfected cell clones revealed equally low invasive activity. Significant differences in the invasive potential of the cell clones MTAP1 and MTAP2 to HT29M3 were revealed. Data are expressed as percentage of invasion with HT29M3 set as 100 per cent (NS: not significant; ^***P<0.001). The stained filters of the Boyden Chamber assay are shown in the lower part of the figure.