Limits...
Procyanidins Negatively Affect the Activity of the Phosphatases of Regenerating Liver.

Stadlbauer S, Rios P, Ohmori K, Suzuki K, Köhn M - PLoS ONE (2015)

Bottom Line: Increasing the number of catechin units in procyanidins to more than three does not further enhance the potency.As PRL overexpression induces cell migration compared to control cells, the effect of procyanidins on this phenotype was studied.Together, our results show that procyanidins negatively affect PRL activity, suggesting that PRLs could be targets in the polypharmacology of natural polyphenols.

View Article: PubMed Central - PubMed

Affiliation: European Molecular Biology Laboratory, Genome Biology Unit, Meyerhofstrasse 1, 69117, Heidelberg, Germany.

ABSTRACT
Natural polyphenols like oligomeric catechins (procyanidins) derived from green tea and herbal medicines are interesting compounds for pharmaceutical research due to their ability to protect against carcinogenesis in animal models. It is nevertheless still unclear how intracellular pathways are modulated by polyphenols. Monomeric polyphenols were shown to affect the activity of some protein phosphatases (PPs). The three phosphatases of regenerating liver (PRLs) are close relatives and promising therapeutic targets in cancer. In the present study we show that several procyanidins inhibit the activity of all three members of the PRL family in the low micromolar range, whereas monomeric epicatechins show weak inhibitory activity. Increasing the number of catechin units in procyanidins to more than three does not further enhance the potency. Remarkably, the tested procyanidins showed selectivity in vitro when compared to other PPs, and over 10-fold selectivity toward PRL-1 over PRL-2 and PRL-3. As PRL overexpression induces cell migration compared to control cells, the effect of procyanidins on this phenotype was studied. Treatment with procyanidin C2 led to a decrease in cell migration of PRL-1- and PRL-3-overexpressing cells, suggesting the compound-dependent inhibition of PRL-promoted cell migration. Treatment with procyanidin B3 led to selective suppression of PRL-1 overexpressing cells, thereby corroborating the selectivity toward PRL-1- over PRL-3 in vitro. Together, our results show that procyanidins negatively affect PRL activity, suggesting that PRLs could be targets in the polypharmacology of natural polyphenols. Furthermore, they are interesting candidates for the development of PRL-1 inhibitors due to their low cellular toxicity and the selectivity within the PRL family.

No MeSH data available.


Related in: MedlinePlus

Cytotoxicity of procyanidin C2 (9) in HEK293 cells.Cells were treated with 50, 150 or 300 μM of 9 in the growth medium for 24 h. Cells were harvested, resuspended in PBS buffer and incubated with propidium iodide (1 mg/mL) for 5 min on ice. 10,000 events were set for the number of living cells. The number of living cells was divided by the number of total cells counted and given as percentage of cell survival. Data represent means ± standard errors of the mean (n = 3).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4520450&req=5

pone.0134336.g005: Cytotoxicity of procyanidin C2 (9) in HEK293 cells.Cells were treated with 50, 150 or 300 μM of 9 in the growth medium for 24 h. Cells were harvested, resuspended in PBS buffer and incubated with propidium iodide (1 mg/mL) for 5 min on ice. 10,000 events were set for the number of living cells. The number of living cells was divided by the number of total cells counted and given as percentage of cell survival. Data represent means ± standard errors of the mean (n = 3).

Mentions: To study the effects of procyanidins on PRL-1 and PRL-3 in cells, the trimeric catechin (procyanidin C2, 9) was chosen as a representative example due to its strong inhibitor activity in vitro toward both PRL-s and its smaller size compared to the higher oligomers, which could influence cell permeability. HEK293 cells stably overexpressing PRL-1 and PRL-3 were chosen as model cell line [45]. As a control cell line, HEK293 cells transfected with the empty vector were utilized (see the Experimental Procedures) [45]. To avoid false positive results due to cell death, first cell viability was studied in a concentration dependent manner by using flow cytometry. Therefore, cells were treated with different concentrations of compound 9 for 24 h, harvested, and then the ratio of living to dead cells was determined using propidium iodide (Fig 5). Treatment with 50 μM of compound 9 did not show any cytotoxic effects in either of the three cell lines, whereas concentrations of 150 and 300 μM generally reduced cell viability to about 50%.


Procyanidins Negatively Affect the Activity of the Phosphatases of Regenerating Liver.

Stadlbauer S, Rios P, Ohmori K, Suzuki K, Köhn M - PLoS ONE (2015)

Cytotoxicity of procyanidin C2 (9) in HEK293 cells.Cells were treated with 50, 150 or 300 μM of 9 in the growth medium for 24 h. Cells were harvested, resuspended in PBS buffer and incubated with propidium iodide (1 mg/mL) for 5 min on ice. 10,000 events were set for the number of living cells. The number of living cells was divided by the number of total cells counted and given as percentage of cell survival. Data represent means ± standard errors of the mean (n = 3).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520450&req=5

pone.0134336.g005: Cytotoxicity of procyanidin C2 (9) in HEK293 cells.Cells were treated with 50, 150 or 300 μM of 9 in the growth medium for 24 h. Cells were harvested, resuspended in PBS buffer and incubated with propidium iodide (1 mg/mL) for 5 min on ice. 10,000 events were set for the number of living cells. The number of living cells was divided by the number of total cells counted and given as percentage of cell survival. Data represent means ± standard errors of the mean (n = 3).
Mentions: To study the effects of procyanidins on PRL-1 and PRL-3 in cells, the trimeric catechin (procyanidin C2, 9) was chosen as a representative example due to its strong inhibitor activity in vitro toward both PRL-s and its smaller size compared to the higher oligomers, which could influence cell permeability. HEK293 cells stably overexpressing PRL-1 and PRL-3 were chosen as model cell line [45]. As a control cell line, HEK293 cells transfected with the empty vector were utilized (see the Experimental Procedures) [45]. To avoid false positive results due to cell death, first cell viability was studied in a concentration dependent manner by using flow cytometry. Therefore, cells were treated with different concentrations of compound 9 for 24 h, harvested, and then the ratio of living to dead cells was determined using propidium iodide (Fig 5). Treatment with 50 μM of compound 9 did not show any cytotoxic effects in either of the three cell lines, whereas concentrations of 150 and 300 μM generally reduced cell viability to about 50%.

Bottom Line: Increasing the number of catechin units in procyanidins to more than three does not further enhance the potency.As PRL overexpression induces cell migration compared to control cells, the effect of procyanidins on this phenotype was studied.Together, our results show that procyanidins negatively affect PRL activity, suggesting that PRLs could be targets in the polypharmacology of natural polyphenols.

View Article: PubMed Central - PubMed

Affiliation: European Molecular Biology Laboratory, Genome Biology Unit, Meyerhofstrasse 1, 69117, Heidelberg, Germany.

ABSTRACT
Natural polyphenols like oligomeric catechins (procyanidins) derived from green tea and herbal medicines are interesting compounds for pharmaceutical research due to their ability to protect against carcinogenesis in animal models. It is nevertheless still unclear how intracellular pathways are modulated by polyphenols. Monomeric polyphenols were shown to affect the activity of some protein phosphatases (PPs). The three phosphatases of regenerating liver (PRLs) are close relatives and promising therapeutic targets in cancer. In the present study we show that several procyanidins inhibit the activity of all three members of the PRL family in the low micromolar range, whereas monomeric epicatechins show weak inhibitory activity. Increasing the number of catechin units in procyanidins to more than three does not further enhance the potency. Remarkably, the tested procyanidins showed selectivity in vitro when compared to other PPs, and over 10-fold selectivity toward PRL-1 over PRL-2 and PRL-3. As PRL overexpression induces cell migration compared to control cells, the effect of procyanidins on this phenotype was studied. Treatment with procyanidin C2 led to a decrease in cell migration of PRL-1- and PRL-3-overexpressing cells, suggesting the compound-dependent inhibition of PRL-promoted cell migration. Treatment with procyanidin B3 led to selective suppression of PRL-1 overexpressing cells, thereby corroborating the selectivity toward PRL-1- over PRL-3 in vitro. Together, our results show that procyanidins negatively affect PRL activity, suggesting that PRLs could be targets in the polypharmacology of natural polyphenols. Furthermore, they are interesting candidates for the development of PRL-1 inhibitors due to their low cellular toxicity and the selectivity within the PRL family.

No MeSH data available.


Related in: MedlinePlus