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Mixtures of xenoestrogens disrupt estradiol-induced non-genomic signaling and downstream functions in pituitary cells.

Viñas R, Watson CS - Environ Health (2013)

Bottom Line: Our study examines the effects of xenoestrogen mixtures on estradiol-induced non-genomic signaling and associated functional responses.Individual bisphenol compounds did not activate JNK, while nonylphenol did; however, the combination of two or three xenoestrogens with estradiol generated an enhanced non-monotonic JNK dose-response.In mixtures expected to be found in contaminated environments, xenoestrogens can have dramatic disrupting effects on hormonal mechanisms of cell regulation and their downstream functional responses, altering cellular responses to physiologic estrogens.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Our study examines the effects of xenoestrogen mixtures on estradiol-induced non-genomic signaling and associated functional responses. Bisphenol-A, used to manufacture plastic consumer products, and nonylphenol, a surfactant, are estrogenic by a variety of assays, including altering many intracellular signaling pathways; bisphenol-S is now used as a bisphenol-A substitute. All three compounds contaminate the environment globally. We previously showed that bisphenol-S, bisphenol-A, and nonylphenol alone rapidly activated several kinases at very low concentrations in the GH3/B6/F10 rat pituitary cell line.

Methods: For each assay we compared the response of individual xenoestrogens at environmentally relevant concentrations (10-15 -10-7 M), to their mixture effects on 10-9 M estradiol-induced responses. We used a medium-throughput plate immunoassay to quantify phosphorylations of extracellular signal-regulated kinases (ERKs) and c-Jun-N-terminal kinases (JNKs). Cell numbers were assessed by crystal violet assay to compare the proliferative effects. Apoptosis was assessed by measuring caspase 8 and 9 activities via the release of the fluorescent product 7-amino-4-trifluoromethylcoumarin. Prolactin release was measured by radio-immunoassay after a 1 min exposure to all individual and combinations of estrogens.

Results: Individual xenoestrogens elicited phospho-activation of ERK in a non-monotonic dose- (fM-nM) and mostly oscillating time-dependent (2.5-60 min) manner. When multiple xenoestrogens were combined with nM estradiol, the physiologic estrogen's response was attenuated. Individual bisphenol compounds did not activate JNK, while nonylphenol did; however, the combination of two or three xenoestrogens with estradiol generated an enhanced non-monotonic JNK dose-response. Estradiol and all xenoestrogen compounds induced cell proliferation individually, while the mixtures of these compounds with estradiol suppressed proliferation below that of the vehicle control, suggesting a possible apoptotic response. Extrinsic caspase 8 activity was suppressed by estradiol, elevated by bisphenol S, and unaffected by mixtures. Intrinsic caspase 9 activity was inhibited by estradiol, and by xenoestrogen combinations (at 10-14 and 10-8 M). Mixtures of xenoestrogens impeded the estradiol-induced release of prolactin.

Conclusions: In mixtures expected to be found in contaminated environments, xenoestrogens can have dramatic disrupting effects on hormonal mechanisms of cell regulation and their downstream functional responses, altering cellular responses to physiologic estrogens.

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Related in: MedlinePlus

XEs cause cell proliferation, and XE mixtures disrupt cell proliferation evoked by E2. Increasing concentrations of XEs (10-15 M – 10-7 M) compared to increasing concentrations of E2 (10-15 M-10-7 M) alone (A) were assessed after a 3-day growth period. Mixtures of E2 with XEs were assessed in B. Cell number was measured by the CV assay and compared to vehicle (V)-treated cells (n = 24 over 3 experiments). All error bars represent S.E M. The width of the vehicle bar represents a S. E. of ± 1.3. * = p < 0.05 compared to vehicle; in B, # = p < 0.05 compared to 10-9 M E2.
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Figure 5: XEs cause cell proliferation, and XE mixtures disrupt cell proliferation evoked by E2. Increasing concentrations of XEs (10-15 M – 10-7 M) compared to increasing concentrations of E2 (10-15 M-10-7 M) alone (A) were assessed after a 3-day growth period. Mixtures of E2 with XEs were assessed in B. Cell number was measured by the CV assay and compared to vehicle (V)-treated cells (n = 24 over 3 experiments). All error bars represent S.E M. The width of the vehicle bar represents a S. E. of ± 1.3. * = p < 0.05 compared to vehicle; in B, # = p < 0.05 compared to 10-9 M E2.

Mentions: After a 3-day exposure, 10-9 M E2 and BPS had similar effects on cell proliferation [28]. We now looked at the dose responsiveness at this 3-day time point, demonstrating non-monotonic stimulations (Figure 5A), as we observed previously with E2 and other XEs [38,40]. NP did not increase cell numbers significantly compared to vehicle until it reached 10-11 M, and BPA until it reached 10-7 M. Both XE mixtures with E2 (Figure 5B) failed to stimulate cell proliferation, but instead suppressed cell numbers far below those seen with vehicle, again showing these compounds’ ability to disrupt a response to a physiologic estrogen.


Mixtures of xenoestrogens disrupt estradiol-induced non-genomic signaling and downstream functions in pituitary cells.

Viñas R, Watson CS - Environ Health (2013)

XEs cause cell proliferation, and XE mixtures disrupt cell proliferation evoked by E2. Increasing concentrations of XEs (10-15 M – 10-7 M) compared to increasing concentrations of E2 (10-15 M-10-7 M) alone (A) were assessed after a 3-day growth period. Mixtures of E2 with XEs were assessed in B. Cell number was measured by the CV assay and compared to vehicle (V)-treated cells (n = 24 over 3 experiments). All error bars represent S.E M. The width of the vehicle bar represents a S. E. of ± 1.3. * = p < 0.05 compared to vehicle; in B, # = p < 0.05 compared to 10-9 M E2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3643824&req=5

Figure 5: XEs cause cell proliferation, and XE mixtures disrupt cell proliferation evoked by E2. Increasing concentrations of XEs (10-15 M – 10-7 M) compared to increasing concentrations of E2 (10-15 M-10-7 M) alone (A) were assessed after a 3-day growth period. Mixtures of E2 with XEs were assessed in B. Cell number was measured by the CV assay and compared to vehicle (V)-treated cells (n = 24 over 3 experiments). All error bars represent S.E M. The width of the vehicle bar represents a S. E. of ± 1.3. * = p < 0.05 compared to vehicle; in B, # = p < 0.05 compared to 10-9 M E2.
Mentions: After a 3-day exposure, 10-9 M E2 and BPS had similar effects on cell proliferation [28]. We now looked at the dose responsiveness at this 3-day time point, demonstrating non-monotonic stimulations (Figure 5A), as we observed previously with E2 and other XEs [38,40]. NP did not increase cell numbers significantly compared to vehicle until it reached 10-11 M, and BPA until it reached 10-7 M. Both XE mixtures with E2 (Figure 5B) failed to stimulate cell proliferation, but instead suppressed cell numbers far below those seen with vehicle, again showing these compounds’ ability to disrupt a response to a physiologic estrogen.

Bottom Line: Our study examines the effects of xenoestrogen mixtures on estradiol-induced non-genomic signaling and associated functional responses.Individual bisphenol compounds did not activate JNK, while nonylphenol did; however, the combination of two or three xenoestrogens with estradiol generated an enhanced non-monotonic JNK dose-response.In mixtures expected to be found in contaminated environments, xenoestrogens can have dramatic disrupting effects on hormonal mechanisms of cell regulation and their downstream functional responses, altering cellular responses to physiologic estrogens.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Our study examines the effects of xenoestrogen mixtures on estradiol-induced non-genomic signaling and associated functional responses. Bisphenol-A, used to manufacture plastic consumer products, and nonylphenol, a surfactant, are estrogenic by a variety of assays, including altering many intracellular signaling pathways; bisphenol-S is now used as a bisphenol-A substitute. All three compounds contaminate the environment globally. We previously showed that bisphenol-S, bisphenol-A, and nonylphenol alone rapidly activated several kinases at very low concentrations in the GH3/B6/F10 rat pituitary cell line.

Methods: For each assay we compared the response of individual xenoestrogens at environmentally relevant concentrations (10-15 -10-7 M), to their mixture effects on 10-9 M estradiol-induced responses. We used a medium-throughput plate immunoassay to quantify phosphorylations of extracellular signal-regulated kinases (ERKs) and c-Jun-N-terminal kinases (JNKs). Cell numbers were assessed by crystal violet assay to compare the proliferative effects. Apoptosis was assessed by measuring caspase 8 and 9 activities via the release of the fluorescent product 7-amino-4-trifluoromethylcoumarin. Prolactin release was measured by radio-immunoassay after a 1 min exposure to all individual and combinations of estrogens.

Results: Individual xenoestrogens elicited phospho-activation of ERK in a non-monotonic dose- (fM-nM) and mostly oscillating time-dependent (2.5-60 min) manner. When multiple xenoestrogens were combined with nM estradiol, the physiologic estrogen's response was attenuated. Individual bisphenol compounds did not activate JNK, while nonylphenol did; however, the combination of two or three xenoestrogens with estradiol generated an enhanced non-monotonic JNK dose-response. Estradiol and all xenoestrogen compounds induced cell proliferation individually, while the mixtures of these compounds with estradiol suppressed proliferation below that of the vehicle control, suggesting a possible apoptotic response. Extrinsic caspase 8 activity was suppressed by estradiol, elevated by bisphenol S, and unaffected by mixtures. Intrinsic caspase 9 activity was inhibited by estradiol, and by xenoestrogen combinations (at 10-14 and 10-8 M). Mixtures of xenoestrogens impeded the estradiol-induced release of prolactin.

Conclusions: In mixtures expected to be found in contaminated environments, xenoestrogens can have dramatic disrupting effects on hormonal mechanisms of cell regulation and their downstream functional responses, altering cellular responses to physiologic estrogens.

Show MeSH
Related in: MedlinePlus