Identification of high‐density lipoprotein in serum to determine anti‐cancer efficacy of doxorubicin in HeLa cells

The cytotoxic effects of doxorubicin (DOX) and daunorubicin (DAU) on HeLa cells cultured under different serum conditions were analyzed by the “nucleophosmin translocation” assay using immunofluorescence. Bright nucleolar fluorescence was observed in untreated cells. A shift from nucleolar to nuclear fluorescence was observed with increasing doses of DOX or DAU, with longer incubation times. A lesser degree of nucleophosmin translocation from nucleoli to nucleoplasm was observed in serum‐deprived cells under the same DOX or DAU treatment. These results correlated well with those of cell‐growth‐reversibility and colony‐formation studies, showing decreased inhibitory effects of growth on cells cultured in medium without serum. Furthermore, cells cultured in medium supplemented with the lipoprotein‐free serum responded to DOX in a similar way to cells cultured without serum. High‐density lipoprotein (HDL) and low‐density lipoprotein (LDL) were then added to the lipoprotein‐free serum. Cells cultured in medium with the HDL‐supplemented, serum showed increased sensitivity to DOX. Inhibition of cell growth and colony formation was observed in such HDL‐supplemented cells upon DOX treatment (30 min). LDL, on the other hand, did not show an increase in the anti‐cancer response. These results suggested that the variation in response of cells to DOX anti‐cancer treatment under different growth conditions may be due to their varied concentrations of HDL. “Nucleophosmin translocation”, which is useful for monitoring and ensuring the efficacy of the drug during anti‐cancer treatment, provides an improved potential for successful chemotherapy.