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Biologic roles of estrogen receptor-β and insulin-like growth factor-2 in triple-negative breast cancer.

Hamilton N, Márquez-Garbán D, Mah V, Fernando G, Elshimali Y, Garbán H, Elashoff D, Vadgama J, Goodglick L, Pietras R - Biomed Res Int (2015)

Bottom Line: To assess ERβ effects on proliferation, ERβ expression in TNBC cells was silenced using shRNA, resulting in a significant reduction in TNBC proliferation.Growth-stimulating effects of ERβ may be due in part to downstream actions that promote VEGF, amphiregulin, and Wnt-10b secretion, other factors associated with tumor promotion.In vivo, insulin-like growth factor-2 (IGF-2), along with ERβ1, is significantly expressed in TNBC and stimulates high ERβ mRNA in TNBC cells.

View Article: PubMed Central - PubMed

Affiliation: UCLA School of Nursing, Los Angeles, CA 90095, USA ; UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA.

ABSTRACT
Triple-negative breast cancer (TNBC) occurs in 10-15% of patients yet accounts for almost half of all breast cancer deaths. TNBCs lack expression of estrogen and progesterone receptors and HER-2 overexpression and cannot be treated with current targeted therapies. TNBCs often occur in African American and younger women. Although initially responsive to some chemotherapies, TNBCs tend to relapse and metastasize. Thus, it is critical to find new therapeutic targets. A second ER gene product, termed ERβ, in the absence of ERα may be such a target. Using human TNBC specimens with known clinical outcomes to assess ERβ expression, we find that ERβ1 associates with significantly worse 5-year overall survival. Further, a panel of TNBC cell lines exhibit significant levels of ERβ protein. To assess ERβ effects on proliferation, ERβ expression in TNBC cells was silenced using shRNA, resulting in a significant reduction in TNBC proliferation. ERβ-specific antagonists similarly suppressed TNBC growth. Growth-stimulating effects of ERβ may be due in part to downstream actions that promote VEGF, amphiregulin, and Wnt-10b secretion, other factors associated with tumor promotion. In vivo, insulin-like growth factor-2 (IGF-2), along with ERβ1, is significantly expressed in TNBC and stimulates high ERβ mRNA in TNBC cells. This work may help elucidate the interplay of metabolic and growth factors in TNBC.

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Estrogen receptor-β agonist DPN promotes expression and activation of EGFR and downstream signaling in MDA-MB-231 cells. (a) Cells were treated with DPN for 15 minutes. Thereafter, cells were lysed and processed for gel electrophoresis and Western immunoblot using antibodies against phosphotyrosine-1068- and total-EGFR, phospho-p44/42- and total-MAPK, and phosphoserine-2448- and total-mTOR. These data are consistent with independent reports on DPN activity [66]. (b) MDA-MB-231 cells were treated with DPN for 24 hours. Then, cells were lysed, processed for gel electrophoresis and Western immunoblot using antibodies to EGFR and HER-3. β-actin was the loading control. Blot shown is representative of at least three independent experiments.
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fig6: Estrogen receptor-β agonist DPN promotes expression and activation of EGFR and downstream signaling in MDA-MB-231 cells. (a) Cells were treated with DPN for 15 minutes. Thereafter, cells were lysed and processed for gel electrophoresis and Western immunoblot using antibodies against phosphotyrosine-1068- and total-EGFR, phospho-p44/42- and total-MAPK, and phosphoserine-2448- and total-mTOR. These data are consistent with independent reports on DPN activity [66]. (b) MDA-MB-231 cells were treated with DPN for 24 hours. Then, cells were lysed, processed for gel electrophoresis and Western immunoblot using antibodies to EGFR and HER-3. β-actin was the loading control. Blot shown is representative of at least three independent experiments.

Mentions: Since EGFR is known to be expressed and active in many TNBCs [1, 64], we explored cross communication between ERβ activation and EGFR in TNBC cells. MDA-MB-231 cells treated with DPN for 15 minutes showed increased phosphorylation of Tyr1068-EGFR as well as downstream signaling demonstrated by phosphorylation of p44/p42-MAPK and phospho-Ser2448-mTOR (see Figure 6(a)). Further, TNBC cells treated with DPN for 24 hours had increased EGFR protein levels but levels of HER-3, a related EGFR family member, were not increased (Figure 6(b)). Our findings in Figure 5 that note ERβ-induced promotion of amphiregulin, a known EGFR ligand, as well as EGFR expression (Figure 6(b)) implicate a cascade that could potentially promote downstream EGFR signaling modules such as the Ras/Raf/MEK/ERK1/2 and mTOR pathway for TNBC progression [15, 65]. Hence, ERβ1 elicits increased phosphorylation of EGFR, as well as activation of MAPK and mTOR.


Biologic roles of estrogen receptor-β and insulin-like growth factor-2 in triple-negative breast cancer.

Hamilton N, Márquez-Garbán D, Mah V, Fernando G, Elshimali Y, Garbán H, Elashoff D, Vadgama J, Goodglick L, Pietras R - Biomed Res Int (2015)

Estrogen receptor-β agonist DPN promotes expression and activation of EGFR and downstream signaling in MDA-MB-231 cells. (a) Cells were treated with DPN for 15 minutes. Thereafter, cells were lysed and processed for gel electrophoresis and Western immunoblot using antibodies against phosphotyrosine-1068- and total-EGFR, phospho-p44/42- and total-MAPK, and phosphoserine-2448- and total-mTOR. These data are consistent with independent reports on DPN activity [66]. (b) MDA-MB-231 cells were treated with DPN for 24 hours. Then, cells were lysed, processed for gel electrophoresis and Western immunoblot using antibodies to EGFR and HER-3. β-actin was the loading control. Blot shown is representative of at least three independent experiments.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4385615&req=5

fig6: Estrogen receptor-β agonist DPN promotes expression and activation of EGFR and downstream signaling in MDA-MB-231 cells. (a) Cells were treated with DPN for 15 minutes. Thereafter, cells were lysed and processed for gel electrophoresis and Western immunoblot using antibodies against phosphotyrosine-1068- and total-EGFR, phospho-p44/42- and total-MAPK, and phosphoserine-2448- and total-mTOR. These data are consistent with independent reports on DPN activity [66]. (b) MDA-MB-231 cells were treated with DPN for 24 hours. Then, cells were lysed, processed for gel electrophoresis and Western immunoblot using antibodies to EGFR and HER-3. β-actin was the loading control. Blot shown is representative of at least three independent experiments.
Mentions: Since EGFR is known to be expressed and active in many TNBCs [1, 64], we explored cross communication between ERβ activation and EGFR in TNBC cells. MDA-MB-231 cells treated with DPN for 15 minutes showed increased phosphorylation of Tyr1068-EGFR as well as downstream signaling demonstrated by phosphorylation of p44/p42-MAPK and phospho-Ser2448-mTOR (see Figure 6(a)). Further, TNBC cells treated with DPN for 24 hours had increased EGFR protein levels but levels of HER-3, a related EGFR family member, were not increased (Figure 6(b)). Our findings in Figure 5 that note ERβ-induced promotion of amphiregulin, a known EGFR ligand, as well as EGFR expression (Figure 6(b)) implicate a cascade that could potentially promote downstream EGFR signaling modules such as the Ras/Raf/MEK/ERK1/2 and mTOR pathway for TNBC progression [15, 65]. Hence, ERβ1 elicits increased phosphorylation of EGFR, as well as activation of MAPK and mTOR.

Bottom Line: To assess ERβ effects on proliferation, ERβ expression in TNBC cells was silenced using shRNA, resulting in a significant reduction in TNBC proliferation.Growth-stimulating effects of ERβ may be due in part to downstream actions that promote VEGF, amphiregulin, and Wnt-10b secretion, other factors associated with tumor promotion.In vivo, insulin-like growth factor-2 (IGF-2), along with ERβ1, is significantly expressed in TNBC and stimulates high ERβ mRNA in TNBC cells.

View Article: PubMed Central - PubMed

Affiliation: UCLA School of Nursing, Los Angeles, CA 90095, USA ; UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA.

ABSTRACT
Triple-negative breast cancer (TNBC) occurs in 10-15% of patients yet accounts for almost half of all breast cancer deaths. TNBCs lack expression of estrogen and progesterone receptors and HER-2 overexpression and cannot be treated with current targeted therapies. TNBCs often occur in African American and younger women. Although initially responsive to some chemotherapies, TNBCs tend to relapse and metastasize. Thus, it is critical to find new therapeutic targets. A second ER gene product, termed ERβ, in the absence of ERα may be such a target. Using human TNBC specimens with known clinical outcomes to assess ERβ expression, we find that ERβ1 associates with significantly worse 5-year overall survival. Further, a panel of TNBC cell lines exhibit significant levels of ERβ protein. To assess ERβ effects on proliferation, ERβ expression in TNBC cells was silenced using shRNA, resulting in a significant reduction in TNBC proliferation. ERβ-specific antagonists similarly suppressed TNBC growth. Growth-stimulating effects of ERβ may be due in part to downstream actions that promote VEGF, amphiregulin, and Wnt-10b secretion, other factors associated with tumor promotion. In vivo, insulin-like growth factor-2 (IGF-2), along with ERβ1, is significantly expressed in TNBC and stimulates high ERβ mRNA in TNBC cells. This work may help elucidate the interplay of metabolic and growth factors in TNBC.

Show MeSH
Related in: MedlinePlus