Endometriosis and Retinoids

Project: Research project

Description

Endometriosis, the pathologic endometrium-like tissue on pelvic organs, develops and persists
in part due to defective apoptosis and is associated with pelvic pain and infertility. During the
previous funding period, we showed that retinoic acid (RA) induces endometrial expression of
HSD17B2, an enzyme responsible for inactivating estradiol. Estradiol is a critical mitogen for
endometriosis that is deficient of HSD17B2. A genome-wide gene expression profiling indicated
strikingly lower expression of multiple RA-related genes in endometriotic tissue compared with
matched endometrium: STRA6, a membrane receptor responsible for retinol (vitamin A) uptake,
and CRABP2, which channels cytosolic RA to its nuclear receptor RARα to enhance apoptosis
and reduce proliferation, were expressed at severely lower levels in endometriosis vs.
endometrium. We find that these genes are primarily expressed in endometrial stromal cells and
regulated by progesterone receptor (PR). We provide functional evidence that retinol and RA
levels and expression of RA-target genes are significantly lower in endometriotic compared with
endometrial stromal cells. Our overall hypothesis is that RA production and action is deficient in
endometriosis compared with normal endometrium. This is responsible for deficient inactivation
of estradiol and enhanced survival leading to persistence of endometriosis. The following aims
will be pursued using established human and baboon experimental model systems of
endometriosis. 1) To determine whether strikingly lower levels of STRA6 result in deficient RA
production and action in endometriotic compared with normal endometrial stromal cells. We will
test the hypothesis whether PR-dependent expression of STRA6 regulates retinol uptake
leading to normal RA production in normal endometrial stromal cells, whereas reduced STRA6
expression causes RA deficiency and enhanced survival in endometriotic stromal cells. 2) To
define the pathologic consequences of CRABP2 deficiency in human endometriotic stromal
cells. We will test the hypothesis whether CRABP2 is necessary for RA/RARα-dependent
apoptosis and inhibition of proliferation in endometrial stromal cells, whereas in its absence, RA
enhances cell survival via an alternative pathway. 3) To define the in vivo roles of the key
genes for RA production and action in the baboon endometriosis model. We will test the
hypothesis whether the key genes for RA production and RARα-targeted action are expressed
in a cycle-dependent manner in normal endometrium and significantly reduced in eutopic
endometrium of baboons with endometriosis and severely deficient in pelvic endometriotic
implants, where cell survival is predominant.
StatusActive
Effective start/end date7/1/156/30/20

Funding

  • National Institute of Child Health and Human Development (5R37HD038691-20)

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Retinoids
Endometriosis
Tretinoin
Stromal Cells
Endometrium
Vitamin A
Papio
Estradiol
Progesterone Receptors
Genes
Cell Survival
Pelvic Pain
Survival
Gene Expression Profiling
Cytoplasmic and Nuclear Receptors
Mitogens
Infertility
Theoretical Models
Genome
Apoptosis