Objective     To detect the influence of ornithine antizyme inhibitor-1 (OAZI-1) overexpression on the sensitivity of mouse melanoma B16-F1 cells to polyamine analog CPENSpm

and to study the underlying mechanism.      Methods     B16-F1 cells with OAZI-1 overexpression were treated with CPENSpm. MTT assay was used to detect cell proliferation. QT-RT-PCR was used to determine the mRNA expression levels of OAZI-1

ornithine decarboxylase (ODC) and ornithine decarboxylase antizyme (OAZ) in B16-F1 cells. RP-HPLC was used to determine the polyamine content in B16-F1 cells. Chemiluminescence assay was used to determine the activity of spermine oxidase (SMO) in B16-F1 cells.      Results     The MTT results showed that OAZI-1 overexpression increased the sensitivity of B16-F1 cells to CPENSpm significantly. The QT-RT-PCR results showed an increased mRNA expression level of ODC but a decreased mRNA expression level of OAZ in B16-F1 cells with OAZI-1 overexpression (B16/over). No further changes of the mRNA expression levels of ODC and OAZ were detected in both B16/over cells and control cells (B16/3.1) after being treated with CPENSpm for 24 h. Compared with those in B16/3.1 cells

the polyamine content was lowered significantly

and the SMO activity was increased in B16/over cells after 24-h CPENSpm treatment.      Conclusion     CPENSpm treatment can largely deplete intracellular polyamine in B16-F1 cells with OAZI-1 overexpression

resulting in increased cytotoxicity on those tumor cells.