The aim of the study was to evaluate the in vitro and in vivo antitumor effects of the
2-amino-4,4alpha-dihydro-4alpha,7-dimethyl-3H-phenoxazine-3-one (Phx-1) on the human
retinoblastoma cell line Y79. The in vitro effects of Phx-1 on cell viability and apoptosis of the human
retinoblastoma Y79 cells, were studied by using colorimetric and flow-cytometric methods. The in vivo antitumor effects of Phx-1 on the human
retinoblastoma Y79 cells subcutaneously transplanted in BALB/c nude mice were studied, examining the
tumor size, the adverse effects on the mice and the histopathological evaluations including
hematoxylin and
eosin and immunohistochemical staining in the mass of
tumors of human
retinoblastoma Y79 cells isolated from the mice. Phx-1 suppressed the viability of Y79 cells dose- and time-dependently and induced apoptosis in Y79 cells in vitro. Phx-1 markedly reduced the growth of Y79 cells transplanted into the mice without causing bodyweight loss. Pathological findings of the
tumor mass isolated from mice revealed that the
tumor of Y79 cells treated with Phx-1 had a decreased mitotic index, decreased expression of Ki67 and p53, no alteration of bcl-2 level and increased
caspase-3 activity compared with the the control. Present results suggested that Phx-1 demonstrated antitumor activity against the human
retinoblastoma Y79 cells in vitro and in vivo, by inhibiting cell growth and inducing apoptosis. In addition, Phx-1 exerted few adverse side effects on the mice. Phx-1 may be a useful
antitumor drug in the treatment of
retinoblastoma, which is the most common and serious intraocular malignant
tumor.