Functional characterization of recurrent FOXA2 mutations seen in endometrial cancers

Abstract

FOXA2, a member of the forkhead family of DNA-binding proteins, is frequently mutated in uterine cancers. Most of the mutations observed in uterine cancers are frameshifts and stops. FOXA2 is considered to be a driver gene in uterine cancers, functioning as a haploinsufficient tumor suppressor. The functional consequences of FOXA2 mutations, however, have not yet been determined. We evaluated the effects that frameshift mutations and a recurrent missense mutation have on FOXA2 transcriptional activity. Recurrent N-terminal frameshifts resulted in truncated proteins that failed to translocate to the nucleus and have no transcriptional activity using an E-cadherin/luciferase reporter assay. Protein abundance was reduced for the recurrent p.S169 W mutation, as was transcriptional activity. A C-terminal frameshift mutation had increased FOXA2 levels evidenced by both Western blot and immunofluorescence. Given that FOXA2 is a recognized activator of E-cadherin (CDH1) expression and E-cadherin's potential role in epithelial-to-mesenchymal transition in a wide range of cancer types, we tested the hypothesis that FOXA2 mutations in primary uterine cancer specimens would be associated with reduced CDH1 transcript levels. qRT-PCR revealed significantly lower levels of CDH1 expression in primary tumors with FOXA2 mutations. Our findings in vitro and in vivo suggest that reduced transcriptional activity associated with FOXA2 mutations in uterine cancers is likely to contribute to protumorigenic changes in gene expression.

FOXA2 suppresses endometrial carcinogenesis and epithelial-mesenchymal transition by regulating enhancer activity

“…Taken together, these results show that Foxa2 acts as an “epithelial gatekeeper and EMT suppressor” to prevent endoderm progenitors from undergoing EMT ( 14 ). In line with these results, we found in an open-ended gene discovery effort with a mouse EC cell line that Foxa2 KD resulted in aberrant expression of EMT markers, including Vimentin , Zeb1/2 , and Cdh1/2 ( 34 ). We also found evidence for a role of Foxa2 in EMT suppression in organoids derived from Foxa2 / Pten primary mouse endometrial tumors; for example, Foxa2 reexpression caused decreased growth and striking loss of both cellular organization and pseudopodial extensions.…”

“…Although one study employed EC cell lines to show that engineered FOXA2 mutations have variable effects on transcription factor activity ( 34 ), the mechanisms by which FOXA2 mutations promote endometrial carcinogenesis remain largely undefined, in part due to the lack of genetic models faithfully recapitulating FOXA2 -driven endometrial tumorigenesis. In this study, we created a genetically engineered model of FOXA2 -deficient EC and used it in combination with human and mouse cancer cell line systems to address diverse critical questions relating to the biological roles of FOXA2 in EC initiation and progression.…”

Glycyrrhizin inhibits the invasion and metastasis of breast cancer cells via upregulation of expressions of miR-200c and e-cadherin

“…These procedures cause the epithelial cells to lose epithelial phenotypic characteristics such as cell polarity and connection with the basement membrane, resulting in mesenchymal phenotypic attributes like high migratory, invasive, antiapoptotic, and extracellular matrix-degradative capacities [13]. The adhesion amongst epithelial cells is due to e-cadherin which is needed for epithelial-mesenchymal transformation [14]. The expression level of e-cadherin mRNA is influenced by miRNA.…”

Endometrial epithelial ARID1A is critical for uterine gland function in early pregnancy establishment

“…Forkhead box a2 (FOXA2), one of three FoxA family transcription factors involved in the development and function of many organs, 14 is necessary for endometrial gland development, LIF expression, and pregnancy establishment in mice. 12,15 Being the only FoxA family member expressed in the mouse and human uterus, FOXA2 is specific to the glandular epithelium, and its mutation or loss of expression has been reported in uterine diseases such as endometrial cancers 16 and endometriosis. [17][18][19] Though its physiological function in the human endometrium is not well characterized, recent evidence indicates that FOXA2 coordinates with other factors and pathways critically involved in uterine receptivity, implantation, and decidualization.…”