title: Increased expression of C-myc messenger-RNA and protein in walker 256 cancer-cells stimulated by bone-derived conditioned media and by transforming-growth-factor-Beta (tgf-Beta).
abstract: Walker 256 (W256) rat cancer cells have been reported to exhibit mitogenic responses to bone-derived factors in vitro and in vivo. We sought to determine whether this growth response is related to early oncogene activation. After 15 and 30 min of exposure to bone-derived conditioned medium (BDCM), there was a significant (2.5-fold) increase in c-myc (but not c-fos) mRNA levels, which returned to control (BGJb medium) levels within 1 h. The percentage of W256 cell nuclei exhibiting c-myc protein was greater after 2 h of exposure to BDCM (61.6%) compared to controls (20.6%). BDCM is known to contain transforming growth factor beta (TGF-beta), and in the presence of EGF (20 ng/ml), a mitogenic concentration of purified TGF-beta (0.1 ng/ml) also induced a 2.3-fold increase in c-myc mRNA expression. We conclude that the mitogenic response of W256 cells to BDCM and to TGF-13 is accompanied by an early induction of c-myc, which may have a role in mediating the growth response.
authors.affiliation: HAMILTON REG CANC CTR,699 CONCESS ST,HAMILTON L8V 5C2,ON,CANADA. MCMASTER UNIV,DEPT PATHOL,HAMILTON L8S 4L8,ONTARIO,CANADA.
authors.forename: P
authors.initials: P
authors.lastname: Kostenuik
authors.forename: F
authors.initials: F
authors.lastname: Orr
authors.forename: L
authors.initials: L
authors.lastname: Arsenault
authors.forename: W
authors.initials: W
authors.lastname: Millarbook
authors.forename: G
authors.initials: G
authors.lastname: Singh