Transforming activity of SYT-SSX1-expressing 3Y1 cells.
(A) Schematic structure of the SYT, SSX1, and SYT-SSX1
proteins. The break point of chromosomal translocation for chimeric
gene production is indicated by a broken line. (B)
Stable expression of SSX1, SYT-SSX1, and SYT in 3Y1 cells.
(Left) Expression levels of SSX1 (lane 1, clone F1–7;
lane 2, F1–10; lane 3, F1–23) and of SYT-SSX1 (lane 4, Y1–8; lane 5,
Y1–17; lane 6, Y1–24) and vector alone (lanes 7–9) analyzed by
anti-SSX antibody. (Right) SYT expression (lane 1, clone
SYT-1; lane 2, SYT-2; lane 3, SYT-4; lane 4, vector) by anti-Flag Ab.
(C) Growth rates of each SSX1-, SYT-SSX1-, and
SYT-expressing cell lines in culture with 10% (Left)
and 2% (Right) serum. The averages of cell numbers of
three independent clones were plotted and standard deviations are
indicated as vertical bars. (D) Analysis of
anchorage-independent growth of SYT-SSX1-expressing cells. The averages
of colony numbers sized larger than 0.2 mm of three independent clones
of each SSX1-, SYT-SSX1-, and SYT-expressing cells were plotted as open
bar graphs with standard deviations indicated as vertical bars. SSX1,
SYT-SSX1, and SYT-expression vectors were transfected to 3Y1 cells and
after selected by G418, resistant clones were plated as polyclonal
state, and the number of the formed colonies were measured. Photographs
of representative colonies are shown on the right. (E)
Tumor growth in nude mice. SYT-SSX1-expressing 3Y1 cells formed tumor
masses at the back and in the peritoneal cavity of nude mice
(Upper Left). Expression levels of SYT-SSX1 in formed
tumors were confirmed by immunostaining (Upper Right)
and immunoblotting (Lower Right). Microscopic appearance
of tumors is shown by hematoxylin-eosin staining (Lower
Left).