Figure 9.

Mitochondrial survivin promotes tumorigenicity. (A) Colony formation in soft agar. Differentially transfected INS-1 cells were plated in semisolid medium and scored for colony formation by phase-contrast microscopy. (B) Quantification of colony formation in soft agar. The experimental conditions were as in A. Data are the mean ± SD of a representative experiment of at least 2 independent determinations. ***P = 0.0001. (C) Kinetics of tumor growth. Stably transfected INS-1 cells were injected subcutaneously in the flank of CB17 SCID/beige mice, and tumor volume was determined at the indicated time intervals. Statistical analysis compared growth of INS-1/Surv versus INS-1/MT-S tumors at day 28 (P = 0.024), day 35 (P = 0.0069), and day 45 (P = 0.015). *P < 0.05; **P < 0.01. (D) Histology. Tissue sections from the indicated INS-1 tumors were stained by H&E, Ki67 reactivity as a measure of cell proliferation, and TUNEL as a measure of apoptosis, in vivo. Magnification, ×400. (E) Mitotic index in vivo. The number of Ki67-positive (proliferating) cells was counted in 7 independent fields, each containing an average of 400 cells. ^#P = 0.031. (F) Apoptotic index in vivo. The number of TUNEL-positive (apoptotic) cells was counted in 7 independent fields, each containing an average of 400 cells.