The present study was designed to evaluate how
estradiol alone or in combination with
G protein-coupled
estrogen receptor (GPER) agonists and GPER and
peroxisome proliferator-activated receptor (
PPAR) antagonists alter the expression of
tumor growth factor β (TGF-β),
cyclooxygenase-2 (COX-2),
hypoxia inducible factor 1-alpha (HIF-1α), and
vascular endothelial growth factor (
VEGF) in mouse testis explants and MA-10 mouse
tumor Leydig cells. In order to define the
hormone-associated signaling pathway, the expression of MAPK and PI3K/Akt was also examined. Tissue explants and cells were treated with
estradiol as well as GPER agonist (
ICI 182,780), GPER antagonist (G-15), PPARα antagonist (
GW6471), and PPARγ antagonist (T00709072) in various combinations. First, we showed that in testis explants GPER and PPARα expressions were activated by the GPER agonist and
estradiol (either alone or in mixtures), whereas PPARγ expression was activated only by GPER agonist. Second, increased TGF-β expression and decreased COX-2 expression were found in all experimental groups of testicular explants and MA-10 cells, except for up-regulated COX-2 expression in
estradiol-treated cells, compared to respective controls. Third,
estradiol treatment led to elevated expression of HIF-1α and
VEGF, while their lower levels versus control were noted in the remaining groups of explants. Finally, we demonstrated the up-regulation of MAPK and PI3Kp85/Akt expressions in
estradiol-treated groups of both ex vivo and in vitro models, whereas
estradiol in mixtures with compounds of agonistic or antagonistic properties either up-regulated or down-regulated signaling
kinase expression levels. Our results suggest that a balanced
estrogen level and its action together with proper GPER and
PPAR signaling play a key role in the maintenance of testis homeostasis. Moreover, changes in TGF-β and COX-2 expressions (that disrupted
estrogen pathway) as well as disturbed GPER-
PPAR signaling observed after
estradiol treatment may be involved in testicular
tumorigenesis.