Effects of telomerase variation on cell tumorigenicity. (A) Soft agar assays were performed for 1301, My-La, FE-PD, and Hut78 cells after viral infection for hTERT overexpression or telomerase inhibition. No colony formation could be observed for FE-PD and Hut78 cells. For 1301 and My-La cells, colonies (>8 cells) were counted in 3 different fields per well. Results were expressed as mean from experiments done in triplicate; vertical bars indicate standard deviation. Significant difference was based on Student t test (**P < .01) vs control (DsRed for hTERT overexpression, and Scramble for telomerase inhibition). (B) Graph shows tumor growth in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice implanted with My-La cells overexpressing hTERT or not (control). In all, 1 × 106 cells were xenografted in 8 mice for each condition, and tumor size was measured twice a week for 24 days. Significant difference was based on Student t test (**P < .01) vs control. (C) Tumor growth (mm3 per day) and final tumor weight were determined at day 24. (D) In all hTERT conditions, visible tumors were detected (2) compared with control mice (1). MyLa cell–derived tumors were stained with Mayer’s hematoxylin (3), and immunohistochemistry identified T-cell staining for CD3 (4) (Dako Cytomation).
