Department of Developmental Biology and Cancer, Albert Einstein College of Medicine, New York, New York 10461.
Colony-stimulating factor-1 (CSF-1) has been primarily characterized as a hematopoietic growth factor required for the proliferation and differentiation of monocytic cells. Recent immunohistological observations have shown that this growth factor is also synthesized by the glandular epithelial cells of the pregnant human endometrium and by first trimester human trophoblasts. In the present study endometrial glands were purified from nonpregnant human endometria collected through the menstrual cycle and examined for CSF-1 mRNA expression. The two major mRNAs (4.0 and 3.0 kilobases in length) detected in midproliferative and midsecretory phases differed in the size of the exon 6 and coded, respectively, for a secreted and a cell surface form of CSF-1. The 3.0-kilobase transcript represented a novel CSF-1 mRNA species that was molecularly cloned and sequenced. These data raise the possibility that CSF-1 may be involved in both distant and cell to cell regulatory pathways of cell proliferation and differentiation in the human endometrium.