G protein-coupled estrogen receptor in colon function, immune regulation and carcinogenesis

Table 1 G protein-coupled estrogen receptor ligands

Agonist	Type
Estrogen (17β-estradiol)	Natural steroid
Bisphenol A	Synthetic xenoestrogen
Genistein	Natural phytoestrogen
Tamoxifen	Synthetic therapeutic
Fulvestrant (ICI 182.780)	Synthetic therapeutic
G-1	Synthetic selective ligand
Antagonist	Type
G15	Synthetic selective ligand
G36	Synthetic selective ligand

Table 2 Processes modulated by G protein-coupled estrogen receptor and their importance in neoplastic transformation of the colon

Features of cancer cells	Process	Anti-tumorigenic	Pro-tumorigenic	Ref.
Proliferation and tumor growth	Apoptosis	Yes	No	[73]
	Cell cycle	Yes	No	[73]
	DNA repair	No	Yes	[64]
	Endoplasmic reticulum stress	Yes	No	[73]
	Estrogen metabolism	No	Yes	[90,91]
	Mitochondrial membrane polarity	Yes	No	[73]
	Oxygen level	Yes under normoxia	Yes under hypoxia	[64]
Migration	Fatty acid metabolism	No	Yes	[107]
	Oxygen level	Yes under normoxia	Yes under hypoxia	[64]