Role of ERβ palmitoylation in the inhibition of human colon cancer cell proliferation

Abstract

The cellular functions regulated by 17b-estradiol (E2) start after the hormone binds to its receptors (i.e., ERa and ERb). These act as ligand-dependent transcription factor transactivating target genes. In addition, E2 induces non-genomic actions, whose activation is triggered by a fraction of the ERs localized at the plasma membrane. Palmitoylation allows ERa to localize at the plasma membrane, to associate with caveolin-1, and, upon E2 stimulation, to activate rapid signals relevant for cell proliferation. The existence of a mechanism, which allows ERb localization at the plasma membrane and its putative role in anti-proliferative E2 effects is completely unknown. Here, the susceptibility of ERb to undergo palmitoylation and the role played by this process has been analyzed in DLD-1 containing endogenous ERb or in HeLa cells transiently transfected with ERb or ERa expression vectors. As for ERa, palmitoylation is necessary for ERb localization at the plasma membrane and its association with caveolin-1 but, in contrast to ERa, the E2 binding increases ERb association with caveolin-1 and the p38 member of MAPK family. Moreover, the palmitoyl acyl transferase (PAT) inhibitor blocks the ability of ERb-E2 complex to activate p38 impairing the receptor-dependent activation of downstream pro-apoptotic cascade (i.e., caspase-3 activation and poly(ADP-ribose)polymerase (PARP) cleavage). Consequently, palmitoylation must be considered to be a molecular device for ERb, which allows these receptors to interact with the plasma membrane and to regulate E2-induced non-genomic functions relevant to the antiproliferative effect of this hormone.

Bisphenol A impairs estradiol‐induced protective effects against DLD‐1 colon cancer cell growth

“…Besides lipid modification, association of ERs to membrane and/or signalling proteins allows the activation of down-stream cascade signals important for E2 effects (12). In particular, we previously reported that the physical association between ERb, caveolin-1, and the un-phosphorylated form of p38 is present in DLD-1 cell line even in the absence of E2 (10). This prompted us to evaluate the effect of BPA on ERb molecular interactions with caveolin-1 and p38.…”

“…Equal amounts of soluble cell extracts were incubated with either 2.0 lg of anticaveolin-1 or anti-ERb antibodies. Cell lysis, immunoprecipitation, and SDS-PAGE were performed as previously described (10). Samples were probed with the indicated antibodies (10), and the reaction was visualized with indirect chemiluminescence.…”

“…Actually, low ERb levels are associated with colonic tumorigenesis and loss of malignant colon cell differentiation (6)(7)(8)(9). In particular, in ERbcontaining DLD-1 colon cancer cell line, E2 binding to ERb both increases receptor association to caveolin-1, a membrane scaffolding protein, and to p38, a member of the mitogen-activated protein kinase family (10). The resulting signal transduction pathways are required for the downstream activation of the caspase-3-dependent pro-apoptotic cascade (10,11).…”

Localisation and endocrine control of hyaluronan synthase (HAS) 2, HAS3 and CD44 expression in sheep granulosa cells

“…Oestradiol receptor (ER) β is present in GCs (Hall et al 2001;Jacob et al 2006;Juengel et al 2006;Deroo et al 2009). Not only does ERβ interact with ERα, but it also regulates cell signalling cascades associated with E2 (Pettersson et al 1997;Koehler et al 2005;Galluzzo et al 2007;Zhao et al 2008). …”

Estrogen and gastrointestinal malignancy

“…75 Rapid non-genomic actions are the subject of much research worldwide and because uncertainty exists as to what exact cellular messaging cascades are involved in these non-genomic events, a wide variety of mediators have been examined. Whether or not classical estrogen receptors are involved in this rapid signalling is uncertain but a membrane bound receptor (which is dependant on palmitoylation for localisation) has been described 76 and is likely involved. It is not known whether ER β migration to the cell membrane accounts for these actions or whether an entirely different receptor isoform exerts the effects.…”