Receptive window might be shorter in patients with endometriosis and lesions cyclically prepare for implantation.

Objective: To investigate whether endometrial receptivity is affected in patients with endometriosis using podocalyxin (PCX) as a functional biomarker and to study how endometriotic lesions display PCX and the potential pathological implications.

Design: We have previously reported that PCX, an anti-adhesion glycoprotein and barrier protector, is dynamically regulated in the endometrium and acts as a key negative regulator of epithelial receptivity. Early in the cycle both luminal epithelium (LE, lining the endometrial surface) and glandular epithelium (GE, residing within the tissue) strongly express PCX, but in the receptive window, PCX is selectively downregulated in LE, switching the endometrial surface to an adhesive state for embryo attachment/implantation; meanwhile, PCX expression is maintained in GE until postreceptivity.

Progesterone suppresses podocalyxin partly by up-regulating miR-145 and miR-199 in human endometrial epithelial cells to enhance receptivity in in vitro models.

Establishment of endometrial surface receptivity is crucial for the initiation of embryo implantation yet the molecular mechanisms are not well understood, especially in humans. We have recently discovered that podocalyxin (PODXL) is a critical negative regulator of human endometrial surface receptivity. PODXL is highly expressed in all epithelial and endothelial cells in the non-receptive endometrium, but down-regulated specifically in the luminal epithelium at receptivity.

Podocalyxin molecular characteristics and endometrial expression: high conservation between humans and macaques but divergence in mice†.

Podocalyxin (PODXL) is a newly identified key negative regulator of human endometrial receptivity, specifically down-regulated in the luminal epithelium at receptivity to permit embryo implantation. Here, we bioinformatically compared the molecular characteristics of PODXL among the human, rhesus macaque, and mouse, determined by immunohistochemistry and in situ hybridization (mouse tissues) whether endometrial PODXL expression is conserved across the three species and examined if PODXL inhibits mouse embryo attachment in vitro. The PODXL gene, mRNA, and protein sequences showed greater similarities between humans and macaques than with mice.

Podocalyxin promotes an impermeable epithelium and inhibits pro-implantation factors to negatively regulate endometrial receptivity.

Embryo implantation is a key step in establishing pregnancy and a major limiting factor in IVF. Implantation requires a receptive endometrium but the mechanisms governing receptivity are not well understood. We have recently discovered that podocalyxin (PCX or PODXL) is a key negative regulator of human endometrial receptivity.

Podocalyxin inhibits human embryo implantation in vitro and luminal podocalyxin in putative receptive endometrium is associated with implantation failure in fertility treatment.

Objective: To study whether endometrial epithelial podocalyxin (PCX) inhibits implantation of human embryos in vitro and in patients undergoing in vitro fertilization (IVF).

Design: We have recently identified PCX as a key negative regulator of endometrial epithelial receptivity. Podocalyxin is expressed in all epithelial cells in the nonreceptive endometrium, but is selectively downregulated in the luminal epithelium (LE) for receptivity.

Podocalyxin is a key negative regulator of human endometrial epithelial receptivity for embryo implantation.

Study Question: How is endometrial epithelial receptivity, particularly adhesiveness, regulated at the luminal epithelial surface for embryo implantation in the human?

Summary Answer: Podocalyxin (PCX), a transmembrane protein, was identified as a key negative regulator of endometrial epithelial receptivity; specific downregulation of PCX in the luminal epithelium in the mid-secretory phase, likely mediated by progesterone, may act as a critical step in converting endometrial surface from a non-receptive to an implantation-permitting state.

What Is Known Already: The human endometrium must undergo major molecular and cellular changes to transform from a non-receptive to a receptive state to accommodate embryo implantation. However, the fundamental mechanisms governing receptivity, particularly at the luminal surface where the embryo first interacts with, are not well understood.

Overexpression of aromatase associated with loss of heterozygosity of the STK11 gene accounts for prepubertal gynecomastia in boys with Peutz-Jeghers syndrome.

Context: Peutz-Jeghers syndrome (PJS) is an autosomal-dominant disorder that arises as a consequence of mutations in the STK11 gene that encodes LKB1. PJS males often have estrogen excess manifesting as gynecomastia and advanced bone age. We and others have previously described an increase in testicular aromatase expression in PJS patients.

CREB-regulated transcription co-activator family stimulates promoter II-driven aromatase expression in preadipocytes.

The dramatically increased prevalence of breast cancer after menopause is of great concern and is correlated with elevated local levels of estrogens. This is mainly due to an increase in aromatase expression driven by its proximal promoter II (PII). We have previously demonstrated that the CREB co-activator CRTC2 binds directly to PII and stimulates its activity via mechanisms involving LKB1-AMPK in response to prostaglandin E(2) (PGE(2)).

HIF-1α stimulates aromatase expression driven by prostaglandin E2 in breast adipose stroma.

Introduction: The majority of postmenopausal breast cancers are estrogen-dependent. Tumor-derived factors, such as prostaglandin E2 (PGE2), stimulate CREB1 binding to cAMP response elements (CREs) on aromatase promoter II (PII), leading to the increased expression of aromatase and biosynthesis of estrogens within human breast adipose stromal cells (ASCs). Hypoxia inducible factor-1α (HIF-1α), a key mediator of cellular adaptation to low oxygen levels, is emerging as a novel prognostic marker in breast cancer.

Endocrine-related cancers and the role of AMPK.

AMP-activated protein kinase (AMPK) is a master regulator of energy homeostasis involved in the regulation of a number of physiological processes including β-oxidation of fatty acids, lipogenesis, protein and cholesterol synthesis, as well as cell cycle inhibition and apoptosis. Important changes to these processes are known to occur in cancer due to changes in AMPK activity within cancer cells and in the periphery. This review aims to present findings relating to the role and regulation of AMPK in endocrine-related cancers.

Promoter-specific effects of metformin on aromatase transcript expression.

Phase III aromatase inhibitors (AIs) are proving successful in the treatment of hormone-dependent postmenopausal breast cancer. Side-effects associated with total body aromatase inhibition have prompted new research into the development of breast-specific AIs. The identification of tissue- and disease-specific usage of aromatase promoters has made the inhibition of aromatase at the transcriptional level an interesting approach.