Previous study using monkey kidney COS-E5 cell suggested that KLLN induces apoptosis and may also regulate cell cycle (6).
To investigate the mechanism of KLLN's anti-tumorigenic effect, we first examined its function on the cell cycle.
Empty vector/scrambled si RNA were used as control for KLLN overexpression/knockdown, and these two controls showed the same growth rate.
(D) MCF-7 cells' migration was measured by an (A) Western blots for KLLN expression in 10 different breast cancer cell lines.
Flow cytometry showed that overexpression of KLLN dramatically increases apoptosis in both MCF-7 and MDA-MB-453 cells (Fig. After KLLN transient transfection, we also observed cell accumulation in S-phase (Fig. To determine whether this increased S-phase is due to a promoted proliferation or S-phase arrest, we treated cells with nocodazole after KLLN expression.
On the one hand, if KLLN promotes cell proliferation, the increased S-phase should be abolished by nocodazole-induced G2 arrest.
However, the mechanism of AR's anti-tumor effect in breast cancer is still not fully understood.
Thus far, the mechanism of how androgens suppress proliferation and induces apoptosis in breast cancer is still not fully understood.(C) After KLLN overexpression or knockdown in MCF-7 and MDA-MB-453 cells, growth rates of the cells were assessed by MTT assay, as previously described (36).Each data point represents a mean value of three independent experiments and the error bars indicate the standard deviation, unless otherwise indicated.Androgen receptor (AR) expression by immunohistochemistry correlates with better prognosis and survival among breast cancer patients.We and others have shown that AR inhibits proliferation and induces apoptosis in breast cancer cells.