HUMAN BREAST-CARCINOMA CELLS TRANSFECTED WITH THE GENE ENCODING A C-MYC PROMOTER-BINDING PROTEIN (MBP-1) INHIBITS TUMORS IN NUDE-MICE

We have identified previously a gene from a human cervical carcinoma cell (HeLa) cDNA expression library that encodes a M(r) similar to 37,000 c-myc promoter-binding protein (MBP-1), which binds to the TATA box sequences of c-myc P2 promoter and exerts a negative regulatory function by down-regulating c-myc expression. In normal human tissues, this cloned gene showed variable expression, In this study, we have demonstrated that introduction of the MBP-1 gene into human breast carcinoma cells reduced their ability to invade through a basement membrane matrix in vitro but did not alter their growth rate, Human breast carcinoma transfected with MBP-1 cells showed a loss of anchorage-independent growth and also suppressed tumor formation in athymic nude mice. These results suggest the possible involvement of MBP-1 as a tumor suppressor gene in human breast carcinoma cells.