title: Progesterone enhances calcitriol antitumor activity by upregulating vitamin D receptor expression and promoting apoptosis in endometrial cancer cells.
abstract: Human studies suggest that progesterone and calcitriol may prove beneficial in preventing or inhibiting oncogenesis, but the underlying mechanism is not fully understood. The current study investigates the effects of progesterone, calcitriol, and their combination on immortalized human endometrial epithelial cells and endometrial cancer cells and identifies their targets of action. Combination treatment with both agents enhanced vitamin D receptor expression and inhibited cell proliferation through caspase-3 activation and induction of G0-G1 cell-cycle arrest with associated downregulation of cyclins D1 and D3 and p27 induction. We used mass spectrometry-based proteomics to measure protein abundance differences between calcitriol-, progesterone-, or combination-exposed endometrial cells. A total of 117 proteins showed differential expression among these three treatments. Four proteins were then selected for validation studies: histone H1.4 (HIST1H1E), histidine triad nucleotide-binding protein 2 (HINT2), IFN-induced, double-stranded RNA-activated protein kinase (EIF2AK2), and Bcl-2-associated X protein (BAX). Abundance levels of selected candidates were low in endometrial cancer cell lines versus the immortalized endometrial epithelial cell line. All four proteins displayed elevated expression in cancer cells upon exposure to calcitriol, progesterone, or the combination. Further BAX analysis through gain- or loss-of-function experiments revealed that upregulation of BAX decreased cell proliferation by changing the BAX:BCL-2 ratio. Knockdown of BAX attenuated progesterone- and calcitriol-induced cell growth inhibition. Our results showed that progesterone and calcitriol upregulate the expression of BAX along with other apoptosis-related proteins, which induce inhibition of endometrial cancer cell growth by apoptosis and cell-cycle arrest.
authors.affiliation: Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
authors.forename: Laura R
authors.initials: LR
authors.lastname: Lee
authors.forename: Pang-Ning
authors.initials: PN
authors.lastname: Teng
authors.forename: Huyen
authors.initials: H
authors.lastname: Nguyen
authors.forename: Brian L
authors.initials: BL
authors.lastname: Hood
authors.forename: Leyla
authors.initials: L
authors.lastname: Kavandi
authors.forename: Guisong
authors.initials: G
authors.lastname: Wang
authors.forename: Jane M
authors.initials: JM
authors.lastname: Turbov
authors.forename: Larry G
authors.initials: LG
authors.lastname: Thaete
authors.forename: Chad A
authors.initials: CA
authors.lastname: Hamilton
authors.forename: George L
authors.initials: GL
authors.lastname: Maxwell
authors.forename: Gustavo C
authors.initials: GC
authors.lastname: Rodriguez
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Conrads
authors.forename: Viqar
authors.initials: V
authors.lastname: Syed
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015153:Blotting, Western; D002117:Calcitriol / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002853:Chromatography, Liquid; D016889:Endometrial Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D004717:Endometrium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006657:Histones / Q000378:metabolism; D006801:Humans; D024101:Mitochondrial Proteins / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D040901:Proteomics; D018167:Receptors, Calcitriol / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D019892:eIF-2 Kinase / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D014408:Biomarkers, Tumor; C533603:Hint2 protein, human; D006657:Histones; D024101:Mitochondrial Proteins; D018167:Receptors, Calcitriol; D051028:bcl-2-Associated X Protein; D011374:Progesterone; C583541:EIF2AK1 protein, human; D019892:eIF-2 Kinase; D002117:Calcitriol