Pre-pregnancy body mass index among pregnant adolescents: gestational weight gain and long-term post partum weight retention.

Study Objective: To determine the relationship between adolescents' pre-pregnancy body mass index (BMI), and gestational weight gain and postpartum weight retention.

Design: We review the medical records of adolescents participating in a prospective cohort study on comprehensive health care and parenting education to determine pre-pregnancy BMI, gestational weight gain, and postpartum weight retention at one year.

Setting: Urban academic hospital clinic.

The effect of estradiol on in vivo tumorigenesis is modulated by the human epidermal growth factor receptor 2/phosphatidylinositol 3-kinase/Akt1 pathway.

To determine whether the epidermal growth factor receptor 2 (ErbB2) and Akt1 can alter the in vivo growth of MCF-7 cells, parental cells or cells stably transfected with constitutively active Akt1 (myr-Akt1) or dominant-negative Akt1 mutants (K179M-Akt1 and R25C-Akt1) were implanted into athymic nude mice. Tumor growth was monitored in the presence or absence of the antiestrogen tamoxifen and the selective ErbB2 inhibitor, AG825. MCF-7 [parental or empty vector transfected, cytomegalovirus (CMV)] and myr-Akt1 cells formed tumors upon estradiol supplementation after 20-30 d (59-, 29-, and 17-fold increase in tumor volume, respectively).

Effect of estradiol on estrogen receptor-alpha gene expression and activity can be modulated by the ErbB2/PI 3-K/Akt pathway.

Epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), and heregulin-beta1 (HRG-beta1), can modulate the expression and activity of the estrogen receptor-alpha (ER-alpha) via the phosphatidylinositol 3-kinase (PI 3-K)/Akt pathway in the ER-alpha-positive breast cancer cell line, MCF-7. Estradiol can also rapidly activate PI 3-K/Akt in these cells (nongenomic effect). The recent study examines whether Akt is involved in the ER-alpha regulation by estradiol (genomic effect).

Heregulin-beta1 regulates the estrogen receptor-alpha gene expression and activity via the ErbB2/PI 3-K/Akt pathway.

This study examines whether the serine/threonine protein kinase, Akt, is involved in the crosstalk between the ErbB2 and estrogen receptor-alpha (ER-alpha) pathways. Treatment of MCF-7 cells with 10(-9) M heregulin-beta1 (HRG-beta1) resulted in a rapid phosphorylation of Akt and a 15-fold increase in Akt activity. Akt phosphorylation was blocked by inhibitors of phosphatidylinositol 3-kinase (PI 3-K), by antiestrogens, the protein tyrosine kinase inhibitor, genistein, and by AG825, a selective ErbB2 inhibitor; but not by AG30, a selective EGFR inhibitor.

Estradiol rapidly activates Akt via the ErbB2 signaling pathway.

Previously, we have demonstrated that the two mitogenic growth factors epidermal growth factor and IGF-I can activate Akt and estrogen receptor-alpha (ERalpha) in the hormone-dependent breast cancer cell line, MCF-7. In this report we now show that estradiol can also rapidly activate phosphatidylinositol 3-kinase (PI 3-K)/Akt and that this effect is mediated by the ErbB2 signaling pathway. Treatment of cells with estradiol resulted in phosphorylation of Akt and a 9-fold increase in Akt activity in 10 min.