TRANSFORMING GROWTH FACTOR-ALPHA MESSENGER-RNA LOCALIZATION IN THE DEVELOPING ADULT-RAT AND HUMAN MAMMARY-GLAND BY INSITU HYBRIDIZATION

Transforming growth factor-α (TGFα) has been implicated in the autocrine growth control of a number of different rodent and human tumor cells, including breast cancer cells. Although TGFα has been detected in a limited number of normal tissues, its distribution and physiological function in the mammary gland are relatively unknown. TGFα mRNA expression was detected by in situ hybridization with a labeled TGFα antisense RNA probe and quantitated by application of computer-assisted digital image processing in both the ductal and alveolar epithelial cells in the virgin rat and nulliparous and parous human mammary glands. During pregnancy and lactation, the level of TGFα mRNA expression in the ductal and alveolar epithelial cells increased two- to threefold, while a heterogeneous yet strong expression of TGFα mRNA could also be detected in approximately 10-15% of the surrounding stromal cells in the pregnant mammary gland. © 1990.