Ectopic expression of (Mm)Kin17 protein inhibits cell proliferation of human tumor-derived cells

To characterize the biological role of Kin17 protein, a mammalian nuclear p rotein which participates in the response to UV and ionizing radiation and binds to curved DNA, EBV-derived vectors carrying (Mm)Kin17 cDNA were const ructed and transfected in tumorigenic cells harboring different p53 profile s (HeLa, H1299, and HCT116) and in immortalized HEK 293 cells. (Mm)Kin17 pr otein expression induced a tremendous decrease in cell proliferation of the three tumorigenic cell lines 2 weeks after transfection. Transfection of H EK 293 cells with an pEBVCMV(Mm)Kin17 plasmid gave rise to numerous (Mm)Kin 17-expressing cells which constantly disappeared with time, preventing the establishment of (Mm)Kin17-expressing cells. Several independent clones wer e isolated from HEK 293 cells carrying a pEBVMT(Mm)Kin17 vector. The two cl ones described here (B223.1 and B223.2) exhibited different (Mm)Kin17 prote in levels and displayed a gradual decrease in their proliferative capacitie s. In B223.1 cells, the basal expression of (Mm)Kin17 greatly reduced plati ng efficiency and cell growth. B223.1 cell morphology was altered, with num erous round-shaped cells whose spreading on the culture support was hampere d. We observed giant multinucleated cells or cells containing micronuclei-l ike structures and/or multilobed nuclei. To conclude, (Mm)Kin17 overexpress ion reduced the proliferation of tumorigenic cells independently of their p 53 status and modified cell growth and cell morphology of established HEK 2 93 cells producing (Mm)Kin17 protein. It is likely that (Mm)Kin17 may inter fere with DNA replication, (C) 1999 Academic Press.