CHARACTERIZATION OF ECTOPICALLY-EXPRESSED ETS1 IN HUMAN COLON-CANCER CELLS - INDUCTION OF PUTATIVE ETS1-TARGET GENE

We have previously shown that the ETS1 gene is expressed in a tissue-s pecific manner, and encodes a transcription factor, that may be involv ed in lymphocyte development, activation and proliferation. To underst and the ETS1 function in non-lymphoid cells, we have ectopically expre ssed ETS1 protein in a human colon cancer cell line, and studied its b iochemical properties. The 51 kDa ETS1 protein expressed in transfecte d cells localized in both the nucleus and the cytoplasm, has similar b iochemical properties compared to ETS1 protein expressed in lymphoid c ells. The ectopically expressed ETS1 binds to the DNA in sequence-spec ific manner and the binding activity is affected by the flanking seque nces outside the 'GGA' core. Our results also demonstrate that the DNA -binding activity of full-length ETS1 is similar in lymphoid and non-l ymphoid cells. The ETS1 expressed in DLD-1 cells is biologically activ e since it induces a 54.5 kDa polypeptide, whose expression level corr elates with the expression of ETS1 in DLD-1 cells.