Proteomic Screening and Lasso Regression Reveal Differential Signaling in Insulin and Insulin-like Growth Factor I (IGF1) Pathways.

Insulin and insulin-like growth factor I (IGF1) influence cancer risk and progression through poorly understood mechanisms. To better understand the roles of insulin and IGF1 signaling in breast cancer, we combined proteomic screening with computational network inference to uncover differences in IGF1 and insulin induced signaling. Using reverse phase protein array, we measured the levels of 134 proteins in 21 breast cancer cell lines stimulated with IGF1 or insulin for up to 48 h.

The estrogen receptor alpha nuclear localization sequence is critical for fulvestrant-induced degradation of the receptor.

Fulvestrant, a selective estrogen receptor down-regulator (SERD) is a pure competitive antagonist of estrogen receptor alpha (ERα). Fulvestrant binds ERα and reduces the receptor's half-life by increasing protein turnover, however, its mechanism of action is not fully understood. In this study, we show that removal of the ERα nuclear localization sequence (ERΔNLS) resulted in a predominantly cytoplasmic ERα that was degraded in response to 17-β-estradiol (E2) but was resistant to degradation by fulvestrant.

Forkhead box A1 (FOXA1) is a key mediator of insulin-like growth factor I (IGF-I) activity.

The insulin-like growth factor receptor (IGF-IR) has been implicated in a number of human tumors, including breast cancer. Data from human breast tumors has demonstrated that IGF-IR is over-expressed and hyper-phosphorylated. Additionally, microarray analysis has shown that IGF-I treatment of MCF7 cells leads to a gene signature comprised of induced and repressed genes, which correlated with luminal B tumors.

Estrogen and insulin-like growth factor-I (IGF-I) independently down-regulate critical repressors of breast cancer growth.

Although estrogen receptor alpha (ERα) and insulin-like growth factor (IGF) signaling are important for normal mammary development and breast cancer, cross-talk between these pathways, particularly at the level of transcription, remains poorly understood. We performed microarray analysis on MCF-7 breast cancer cells treated with estradiol (E2) or IGF-I for 3 or 24 h. IGF-I regulated mRNA of five to tenfold more genes than E2, and many genes were co-regulated by both ligands.

Proteomic and transcriptomic profiling reveals a link between the PI3K pathway and lower estrogen-receptor (ER) levels and activity in ER+ breast cancer.

Introduction: Accumulating evidence suggests that both levels and activity of the estrogen receptor (ER) and the progesterone receptor (PR) are dramatically influenced by growth-factor receptor (GFR) signaling pathways, and that this crosstalk is a major determinant of both breast cancer progression and response to therapy. The phosphatidylinositol 3-kinase (PI3K) pathway, a key mediator of GFR signaling, is one of the most altered pathways in breast cancer. We thus examined whether deregulated PI3K signaling in luminal ER+ breast tumors is associated with ER level and activity and intrinsic molecular subtype.

The type I insulin-like growth factor receptor pathway: a key player in cancer therapeutic resistance.

The insulin-like growth factor (IGF) ligands stimulate cellular proliferation and survival by activating the type I insulin-like growth factor receptor (IGF-IR). As a result, the IGF signaling system is implicated in a number of cancers, including those of the breast, prostate, and lung. In addition to mitogenic and anti-apoptotic roles that may directly influence tumor development, IGF-IR also appears to be a critical determinant of response to numerous cancer therapies.