Amplified in breast cancer 4
(AIB4)

???

Gene: maps to 20q11.
mRNA: size: 4.4 kb (Guan X.Y. et al., 1996).
Protein: no data available.

AIB4 maps to the long arm of chromosome 20, one of the most recurrent sites (along with 1q, 8q, and 17q) of DNA copy gains in breast cancers (up to 18% of primary tumors and 40% of cell lines).

Cell lines:
- Amplification of AIB4 gene and incresed expression of AIB4 mRNA were found in BT-474, but not in MCF-7, breast cancer cell (BCC) line (Guan X.Y. et al., 1996).

- By FISH analysis, amplification of the AIB3/AIB4 gene locus was found in MDA-MB-361, UACC-893 (1.5-3-fold amplification), BT-474, SK-BR-3, UACC-812 (>3-fold amplification), but not in MCF-7 and MDA-MB-157 BCC lines (Tanner M.M. et al., 1996).

Tumors:
- By FISH analysis, 13/146 breast carcinomas exhibited a 1.5-3-fold amplification of the AIB3/AIB4 gene locus. A >3-fold amplification was seen in 9/146 samples (Tanner M.M. et al., 1996).

Guan X.Y. et al. (1996) Hybrid selection of transcribed sequences from microdissected DNA: isolation of genes within amplified region at 20q11-q13.2 in breast cancer. Cancer Res. 56, 3446-3450.
Tanner M.M. et al. (1996) Independent amplification and frequent co-amplification of three nonsyntenic regions on the long arm of chromosome 20 in human breast cancer. Cancer Res. 56, 3441-3445.