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Neuroglobin, a pro-survival player in estrogen receptor α-positive cancer cells.

Fiocchetti M, Nuzzo MT, Totta P, Acconcia F, Ascenzi P, Marino M - Cell Death Dis (2014)

Bottom Line: E2 induced the upregulation of NGB in a dose- and time-dependent manner in MCF-7, HepG2, SK-N-BE, and HeLa cells transfected with estrogen receptor α (ERα), whereas E2 was unable to modulate the NGB expression in the ERα-devoid HeLa cells.Both transcriptional and extranuclear ERα signals were required for the E2-dependent upregulation of NGB in MCF-7 and HepG2 cell lines.E2 stimulation modified NGB intracellular localization, inducing a significant reduction of NGB in the nucleus with a parallel increase of NGB in the mitochondria in both HepG2 and MCF-7 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Science, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy.

ABSTRACT
Recently, we reported that human neuroglobin (NGB) is a new player in the signal transduction pathways that lead to 17β-estradiol (E2)-induced neuron survival. Indeed, E2 induces in neuron mitochondria the enhancement of NGB level, which in turn impairs the activation of a pro-apoptotic cascade. Nowadays, the existence of a similar pathway activated by E2 in non-neuronal cells is completely unknown. Here, the role of E2-induced NGB upregulation in tumor cells is reported. E2 induced the upregulation of NGB in a dose- and time-dependent manner in MCF-7, HepG2, SK-N-BE, and HeLa cells transfected with estrogen receptor α (ERα), whereas E2 was unable to modulate the NGB expression in the ERα-devoid HeLa cells. Both transcriptional and extranuclear ERα signals were required for the E2-dependent upregulation of NGB in MCF-7 and HepG2 cell lines. E2 stimulation modified NGB intracellular localization, inducing a significant reduction of NGB in the nucleus with a parallel increase of NGB in the mitochondria in both HepG2 and MCF-7 cells. Remarkably, E2 pretreatment did not counteract the H2O2-induced caspase-3 and poly (ADP-ribose) polymerase 1 (PARP-1) cleavage, as well as Bcl-2 overexpression in MCF-7 and HepG2 cells in which NGB was stably silenced by using shRNA lentiviral particles, highlighting the pivotal role of NGB in E2-induced antiapoptotic pathways in cancer cells. Present results indicate that the E2-induced NGB upregulation in cancer cells could represent a defense mechanism of E2-related cancers rendering them insensitive to oxidative stress. As a whole, these data open new avenues to develop therapeutic strategies against E2-related cancers.

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Related in: MedlinePlus

Effect of E2 on NGB protein levels in HepG2 and MCF-7 cells. Western blot analysis of E2 dose-dependent effect (0.1–1000 nM) on NGB levels after 24 h of stimulation in (a) HepG2 and (b) MCF-7 cells. Time-course analysis of E2 treatment (10 nM) on NGB level in (c) HepG2 and (d) MCF-7 cells on NGB level. The amount of protein was normalized by comparison with tubulin levels. Top panels are typical western blots of three independent experiments. Bottom panels represent the results of the densitometric analyses
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fig2: Effect of E2 on NGB protein levels in HepG2 and MCF-7 cells. Western blot analysis of E2 dose-dependent effect (0.1–1000 nM) on NGB levels after 24 h of stimulation in (a) HepG2 and (b) MCF-7 cells. Time-course analysis of E2 treatment (10 nM) on NGB level in (c) HepG2 and (d) MCF-7 cells on NGB level. The amount of protein was normalized by comparison with tubulin levels. Top panels are typical western blots of three independent experiments. Bottom panels represent the results of the densitometric analyses

Mentions: In all the E2-responsive cancer cells tested, E2 induced a dose- and time-dependent increase in NGB levels with a maximum effect at 10 nM (24 h) (Figures 2a and b). The E2 (10 nM) effect on the NGB level began to be significant 2 (HepG2) and 4 h (MCF-7) after the hormone treatment and remained constant until 24 h (Figures 2c and d). According to these results, 10 nM E2 and 24 h of stimulation were used in the following experiments.


Neuroglobin, a pro-survival player in estrogen receptor α-positive cancer cells.

Fiocchetti M, Nuzzo MT, Totta P, Acconcia F, Ascenzi P, Marino M - Cell Death Dis (2014)

Effect of E2 on NGB protein levels in HepG2 and MCF-7 cells. Western blot analysis of E2 dose-dependent effect (0.1–1000 nM) on NGB levels after 24 h of stimulation in (a) HepG2 and (b) MCF-7 cells. Time-course analysis of E2 treatment (10 nM) on NGB level in (c) HepG2 and (d) MCF-7 cells on NGB level. The amount of protein was normalized by comparison with tubulin levels. Top panels are typical western blots of three independent experiments. Bottom panels represent the results of the densitometric analyses
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4237245&req=5

fig2: Effect of E2 on NGB protein levels in HepG2 and MCF-7 cells. Western blot analysis of E2 dose-dependent effect (0.1–1000 nM) on NGB levels after 24 h of stimulation in (a) HepG2 and (b) MCF-7 cells. Time-course analysis of E2 treatment (10 nM) on NGB level in (c) HepG2 and (d) MCF-7 cells on NGB level. The amount of protein was normalized by comparison with tubulin levels. Top panels are typical western blots of three independent experiments. Bottom panels represent the results of the densitometric analyses
Mentions: In all the E2-responsive cancer cells tested, E2 induced a dose- and time-dependent increase in NGB levels with a maximum effect at 10 nM (24 h) (Figures 2a and b). The E2 (10 nM) effect on the NGB level began to be significant 2 (HepG2) and 4 h (MCF-7) after the hormone treatment and remained constant until 24 h (Figures 2c and d). According to these results, 10 nM E2 and 24 h of stimulation were used in the following experiments.

Bottom Line: E2 induced the upregulation of NGB in a dose- and time-dependent manner in MCF-7, HepG2, SK-N-BE, and HeLa cells transfected with estrogen receptor α (ERα), whereas E2 was unable to modulate the NGB expression in the ERα-devoid HeLa cells.Both transcriptional and extranuclear ERα signals were required for the E2-dependent upregulation of NGB in MCF-7 and HepG2 cell lines.E2 stimulation modified NGB intracellular localization, inducing a significant reduction of NGB in the nucleus with a parallel increase of NGB in the mitochondria in both HepG2 and MCF-7 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Science, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy.

ABSTRACT
Recently, we reported that human neuroglobin (NGB) is a new player in the signal transduction pathways that lead to 17β-estradiol (E2)-induced neuron survival. Indeed, E2 induces in neuron mitochondria the enhancement of NGB level, which in turn impairs the activation of a pro-apoptotic cascade. Nowadays, the existence of a similar pathway activated by E2 in non-neuronal cells is completely unknown. Here, the role of E2-induced NGB upregulation in tumor cells is reported. E2 induced the upregulation of NGB in a dose- and time-dependent manner in MCF-7, HepG2, SK-N-BE, and HeLa cells transfected with estrogen receptor α (ERα), whereas E2 was unable to modulate the NGB expression in the ERα-devoid HeLa cells. Both transcriptional and extranuclear ERα signals were required for the E2-dependent upregulation of NGB in MCF-7 and HepG2 cell lines. E2 stimulation modified NGB intracellular localization, inducing a significant reduction of NGB in the nucleus with a parallel increase of NGB in the mitochondria in both HepG2 and MCF-7 cells. Remarkably, E2 pretreatment did not counteract the H2O2-induced caspase-3 and poly (ADP-ribose) polymerase 1 (PARP-1) cleavage, as well as Bcl-2 overexpression in MCF-7 and HepG2 cells in which NGB was stably silenced by using shRNA lentiviral particles, highlighting the pivotal role of NGB in E2-induced antiapoptotic pathways in cancer cells. Present results indicate that the E2-induced NGB upregulation in cancer cells could represent a defense mechanism of E2-related cancers rendering them insensitive to oxidative stress. As a whole, these data open new avenues to develop therapeutic strategies against E2-related cancers.

Show MeSH
Related in: MedlinePlus