IAP is a family of protein that has baculovirus IAP repeat (BIR) domains an
d inhibits apoptosis. We found a human IAP family gene, which we named Apol
lon, encoding a huge protein (530 kDa) that contains a single BIR domain an
d a ubiquitin-conjugating enzyme domain, that is a human homolog of BRUCE.
Apollon protein was expressed in four of six brain cancers (gliomas), and o
ne of five ovarian cancers in 38 human cancer cell lines that we examined.
Among the brain cancer cell lines, SNB-78 expressed a high level of Apollon
, and this cell line shows resistance against various anticancer drugs. Tre
ating SNB-78 cells with antisense oligonucleotide against Apollon reduced t
he expression of Apollon protein, and significantly sensitized the cells to
apoptosis induced by cisplatin and camptothecin. These results suggest tha
t Apollon protects SNB-78 cells from undergoing apoptosis and, at least in
part, plays a role in tumorigenesis and drug resistance of this cell line.
(C) 1999 Academic Press.