Identification of a messenger ribonucleic acid fraction in @entity1 XXXX cells coding for a novel osteoblast-stimulating factor.

@entity1 @entity263 @entity1238 @entity5 @entity665 @entity421 @entity35
@entity263 is frequently associated with new bone formation although the @entity5 -derived factors responsible for changes in bone cell function have not been identified. We have examined the synthesis of osteoblast-stimulating factors in a cultured @entity1 @entity263 cell line (PC-3) and show that conditioned medium from PC-3 cells stimulate mitogenesis and alkaline phosphatase in cells with the osteoblast phenotype (cultured @entity35 @entity421 cells) and collagen synthesis in fetal @entity35 calvaria. In order to characterize @entity5 -derived gene products which stimulate cells of the osteoblast phenotype messenger RNA (mRNA) was isolated from PC-3 cells and microinjected into @entity1238 oocytes. mRNA-directed translation products which were secreted into the oocyte medium were collected and assayed for a number of osteoblast stimulating properties. Translation products from PC-3 mRNA-injected oocytes stimulated division of cultured @entity421 cells by 8-fold and increased DNA synthesis as measured by incorporation of @entity665 into these cells. In addition, @entity5 -derived translation products stimulated the production of alkaline phosphatase activity, a marker enzyme for bone formation, in cultured @entity421 cells. Oocytes injected either with water or with mRNA from a @entity5 not associated with bone formation were devoid of these activities. Total mRNA from the @entity1 @entity263 cells was then denatured and fractionated by size by agarose gel electrophoresis. When individual fractions of mRNA were eluted from the gel, translated in @entity1238 oocytes, and the secreted translation products were tested for alkaline phosphatase-stimulating activity on osteoblast-like cells, the majority of the activity could be recovered in a mRNA fraction which was approximately 1800 bases in length. These results indicate that the @entity263 cell line synthesizes a mRNA of approximately 1800 bases which codes for a heretofore unrecognized osteoblast-stimulating factor.
