Subtraction hybridization using a cDNA library prepared from temporall
y spaced mRNAs from human melanoma cells treated with recombinant huma
n fibroblast interferon (IFN-beta) plus mezerein (MEZ) that induces te
rminal differentiation (tester cDNA library) and a temporally spaced c
DNA library prepared from actively proliferating melanoma cells (drive
r cDNA library) produced a Temporally Spaced Subtracted (TSS) cDNA lib
rary. This approach resulted in the identification of melanoma differe
ntiation associated (mda) genes displaying both enhanced and suppresse
d expression during growth inhibition and differentiation. In the pres
ent report, we describe a novel cDNA mda-9 that consists of 2084 nucle
otides, and encodes a protein of 298 amino acids with a predicted M-r
of approx. 33 kDa. Treatment of human SV40-immortalized normal melanom
a cells with immune interferon, INF-gamma, induces growth suppression
and enhances mda-9 expression without inducing terminal differentiatio
n. These results establish that induction of terminal differentiation
in human melanoma cells, using the combination of a type I interferon
(IFN-beta) + MEZ, can elicit signaling pathways and gene expression ch
anges also regulated by type II immune interferon. (C) 1998 Elsevier S
cience B.V.