Related Experiment Video
Updated: Feb 23, 2026

Systems Biology of Metabolic Regulation by Estrogen Receptor Signaling in Breast Cancer
Published on: March 17, 2016
Api5 a new cofactor of estrogen receptor alpha involved in breast cancer outcome
Céline Basset1,2, Florence Bonnet-Magnaval3, Marina Garcia-Jove Navarro3
1U1037-CRCT, INSERM, Université Toulouse, F-31037, Toulouse, France.
Abstract:
Api5 (Apoptosis inhibitor 5) is an anti-apoptotic factor that confers resistance to genotoxic stress in human cancer. Api5 is also expressed in endothelial cells and participates to the Estrogen Receptor α (ERα) signaling to promote cell migration. In this study, we found an over expression of Api5 in human breast cancer. Given that we show that high expression of Api5 in breast cancer patients is associated with shorter recurrence free survival, we investigated the relationship between ERα and Api5 at the molecular level. We found that Api5 Nuclear Receptor box (NR box) drives a direct interaction with the C domain of ERα. Furthermore, Api5 participates to gene transcription activation of ERα target genes upon estrogen treatment. Besides, Api5 expression favors tumorigenicity and migration and is necessary for tumor growth in vivo in mice xenografted model of breast cancer cell line. These finding suggest that Api5 is a new cofactor of ERα that functionally participates to the tumorigenic phenotype of breast cancer cells. In ERα breast cancer patients, Api5 overexpression is associated with poor survival, and may be used as a predictive marker of breast cancer recurrence free survival.
Related Concept Videos
Mitogens and the Cell Cycle
Transducer Mechanism: Nuclear Receptors
About 48 different soluble family members of nuclear receptors are identified that can be divided into two main classes:
Secondary Messengers in Hormone Action
Many hormones bind to transmembrane G protein-coupled receptors that connect to regulatory G proteins. These G proteins can then activate enzymes such as adenylyl cyclase or phospholipase C. Adenylyl cyclase converts ATP to cAMP, activating...
Endocrine Signaling
Hormonal Control of the Ovarian Cycle
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle. At puberty, GnRH secretion increases in both frequency and...

