Acidification-and-recovery induces nuclear accumulation of neutral red and DNA into human KB oral carcinoma cells

In cultures of oral cancers, gene transfer has been achieved by delivery systems which introduce DNA into cells but not specifically into the nucleus. We observed that acidification and recovery converted the nuclear-insulated interphase KB carcinoma cells into intense nuclear-accumulating states. Nuclear sequestration of the vital dye neutral red and T7 oligonucleotide was demonstrated qualitatively, and quantitatively by image analysis of single cells. pGemβgal plasmids of 6.8 kb were introduced into KB cells by similar acidification and recovery pulses. Successful integration into the host KB genome was shown by expression of the lacZ gene of the plasmids. Enhanced nucleo-cytoplasmic transport demonstrated here in KB oral epidermoid carcinoma cells could potentially facilitate gene therapy in oral cancers.