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Omega 3 fatty acids chemosensitize multidrug resistant colon cancer cells by down-regulating cholesterol synthesis and altering detergent resistant membranes composition.

Gelsomino G, Corsetto PA, Campia I, Montorfano G, Kopecka J, Castella B, Gazzano E, Ghigo D, Rizzo AM, Riganti C - Mol. Cancer (2013)

Bottom Line: MDR cells, which overexpressed Pgp and MRP1, had a dysregulated cholesterol metabolism, due to the lower expression of ubiquitin E3 ligase Trc8: this produced lower ubiquitination rate of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCoAR), higher cholesterol synthesis, higher cholesterol content in MDR cells.We found that DHA and EPA re-activated Trc8 E3 ligase in MDR cells, restored the ubiquitination rate of HMGCoAR to levels comparable with chemosensitive cells, reduced the cholesterol synthesis and incorporation in DRMs. Omega 3 PUFAs were incorporated in whole lipids as well as in DRMs of MDR cells, and altered the lipid composition of these compartments.They reduced the amount of Pgp and MRP1 contained in DRMs, decreased the transporters activity, restored the antitumor effects of different chemotherapeutic drugs, restored a proper tumor-immune system recognition in response to chemotherapy in MDR cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Oncology, University of Torino, via Santena 5/bis, 10126 Torino, Italy. dario.ghigo@unito.it.

ABSTRACT

Background: The activity of P-glycoprotein (Pgp) and multidrug resistance related protein 1 (MRP1), two membrane transporters involved in multidrug resistance of colon cancer, is increased by high amounts of cholesterol in plasma membrane and detergent resistant membranes (DRMs). It has never been investigated whether omega 3 polyunsatured fatty acids (PUFAs), which modulate cholesterol homeostasis in dyslipidemic syndromes and have chemopreventive effects in colon cancer, may affect the response to chemotherapy in multidrug resistant (MDR) tumors.

Methods: We studied the effect of omega 3 PUFAs docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in human chemosensitive colon cancer HT29 cells and in their MDR counterpart, HT29-dx cells.

Results: MDR cells, which overexpressed Pgp and MRP1, had a dysregulated cholesterol metabolism, due to the lower expression of ubiquitin E3 ligase Trc8: this produced lower ubiquitination rate of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCoAR), higher cholesterol synthesis, higher cholesterol content in MDR cells. We found that DHA and EPA re-activated Trc8 E3 ligase in MDR cells, restored the ubiquitination rate of HMGCoAR to levels comparable with chemosensitive cells, reduced the cholesterol synthesis and incorporation in DRMs. Omega 3 PUFAs were incorporated in whole lipids as well as in DRMs of MDR cells, and altered the lipid composition of these compartments. They reduced the amount of Pgp and MRP1 contained in DRMs, decreased the transporters activity, restored the antitumor effects of different chemotherapeutic drugs, restored a proper tumor-immune system recognition in response to chemotherapy in MDR cells.

Conclusions: Our work describes a new biochemical effect of omega 3 PUFAs, which can be useful to overcome chemoresistance in MDR colon cancer cells.

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Effects of ω6PUFAs and ω3PUFAs on cholesterol synthesis and cells viability in colon cancer cells. HT29 and HT29-dx cells were incubated for 24 h in the absence (CTRL) or in the presence of various concentrations (25, 50, 100, 200 μM) of arachidonic acid (AA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and subjected to the following investigations. (A) Cells were grown in a medium containing [3H]acetate, then the de novo synthesis of cholesterol was measured in duplicate as described in Methods. Data are presented as means ± SD (n = 4). Versus CTRL HT29 cells: * p < 0.05; versus CTRL HT29-dx cells: ° p < 0.05. (B) Cells were stained with Neutral Red solution and the absorbance of viable cells was measured in triplicate spectrophotometrically. Data are presented as means ± SD (n = 4). Versus respective CTRL: * p < 0.05.
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Figure 1: Effects of ω6PUFAs and ω3PUFAs on cholesterol synthesis and cells viability in colon cancer cells. HT29 and HT29-dx cells were incubated for 24 h in the absence (CTRL) or in the presence of various concentrations (25, 50, 100, 200 μM) of arachidonic acid (AA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and subjected to the following investigations. (A) Cells were grown in a medium containing [3H]acetate, then the de novo synthesis of cholesterol was measured in duplicate as described in Methods. Data are presented as means ± SD (n = 4). Versus CTRL HT29 cells: * p < 0.05; versus CTRL HT29-dx cells: ° p < 0.05. (B) Cells were stained with Neutral Red solution and the absorbance of viable cells was measured in triplicate spectrophotometrically. Data are presented as means ± SD (n = 4). Versus respective CTRL: * p < 0.05.

Mentions: Chemoresistant HT29-dx colon cancer cells exhibited a significantly higher synthesis of cholesterol when compared to chemosensitive HT29 cells (Figure 1A). The ω6PUFA AA did not affect the cholesterol synthesis in both cell lines, except at 200 μM AA; ω3PUFAs DHA and EPA decreased the cholesterol synthesis starting from 50 μM. Such decrease was more pronounced and statistically significant in HT29-dx cells (Figure 1A).


Omega 3 fatty acids chemosensitize multidrug resistant colon cancer cells by down-regulating cholesterol synthesis and altering detergent resistant membranes composition.

Gelsomino G, Corsetto PA, Campia I, Montorfano G, Kopecka J, Castella B, Gazzano E, Ghigo D, Rizzo AM, Riganti C - Mol. Cancer (2013)

Effects of ω6PUFAs and ω3PUFAs on cholesterol synthesis and cells viability in colon cancer cells. HT29 and HT29-dx cells were incubated for 24 h in the absence (CTRL) or in the presence of various concentrations (25, 50, 100, 200 μM) of arachidonic acid (AA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and subjected to the following investigations. (A) Cells were grown in a medium containing [3H]acetate, then the de novo synthesis of cholesterol was measured in duplicate as described in Methods. Data are presented as means ± SD (n = 4). Versus CTRL HT29 cells: * p < 0.05; versus CTRL HT29-dx cells: ° p < 0.05. (B) Cells were stained with Neutral Red solution and the absorbance of viable cells was measured in triplicate spectrophotometrically. Data are presented as means ± SD (n = 4). Versus respective CTRL: * p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4225767&req=5

Figure 1: Effects of ω6PUFAs and ω3PUFAs on cholesterol synthesis and cells viability in colon cancer cells. HT29 and HT29-dx cells were incubated for 24 h in the absence (CTRL) or in the presence of various concentrations (25, 50, 100, 200 μM) of arachidonic acid (AA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and subjected to the following investigations. (A) Cells were grown in a medium containing [3H]acetate, then the de novo synthesis of cholesterol was measured in duplicate as described in Methods. Data are presented as means ± SD (n = 4). Versus CTRL HT29 cells: * p < 0.05; versus CTRL HT29-dx cells: ° p < 0.05. (B) Cells were stained with Neutral Red solution and the absorbance of viable cells was measured in triplicate spectrophotometrically. Data are presented as means ± SD (n = 4). Versus respective CTRL: * p < 0.05.
Mentions: Chemoresistant HT29-dx colon cancer cells exhibited a significantly higher synthesis of cholesterol when compared to chemosensitive HT29 cells (Figure 1A). The ω6PUFA AA did not affect the cholesterol synthesis in both cell lines, except at 200 μM AA; ω3PUFAs DHA and EPA decreased the cholesterol synthesis starting from 50 μM. Such decrease was more pronounced and statistically significant in HT29-dx cells (Figure 1A).

Bottom Line: MDR cells, which overexpressed Pgp and MRP1, had a dysregulated cholesterol metabolism, due to the lower expression of ubiquitin E3 ligase Trc8: this produced lower ubiquitination rate of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCoAR), higher cholesterol synthesis, higher cholesterol content in MDR cells.We found that DHA and EPA re-activated Trc8 E3 ligase in MDR cells, restored the ubiquitination rate of HMGCoAR to levels comparable with chemosensitive cells, reduced the cholesterol synthesis and incorporation in DRMs. Omega 3 PUFAs were incorporated in whole lipids as well as in DRMs of MDR cells, and altered the lipid composition of these compartments.They reduced the amount of Pgp and MRP1 contained in DRMs, decreased the transporters activity, restored the antitumor effects of different chemotherapeutic drugs, restored a proper tumor-immune system recognition in response to chemotherapy in MDR cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Oncology, University of Torino, via Santena 5/bis, 10126 Torino, Italy. dario.ghigo@unito.it.

ABSTRACT

Background: The activity of P-glycoprotein (Pgp) and multidrug resistance related protein 1 (MRP1), two membrane transporters involved in multidrug resistance of colon cancer, is increased by high amounts of cholesterol in plasma membrane and detergent resistant membranes (DRMs). It has never been investigated whether omega 3 polyunsatured fatty acids (PUFAs), which modulate cholesterol homeostasis in dyslipidemic syndromes and have chemopreventive effects in colon cancer, may affect the response to chemotherapy in multidrug resistant (MDR) tumors.

Methods: We studied the effect of omega 3 PUFAs docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in human chemosensitive colon cancer HT29 cells and in their MDR counterpart, HT29-dx cells.

Results: MDR cells, which overexpressed Pgp and MRP1, had a dysregulated cholesterol metabolism, due to the lower expression of ubiquitin E3 ligase Trc8: this produced lower ubiquitination rate of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCoAR), higher cholesterol synthesis, higher cholesterol content in MDR cells. We found that DHA and EPA re-activated Trc8 E3 ligase in MDR cells, restored the ubiquitination rate of HMGCoAR to levels comparable with chemosensitive cells, reduced the cholesterol synthesis and incorporation in DRMs. Omega 3 PUFAs were incorporated in whole lipids as well as in DRMs of MDR cells, and altered the lipid composition of these compartments. They reduced the amount of Pgp and MRP1 contained in DRMs, decreased the transporters activity, restored the antitumor effects of different chemotherapeutic drugs, restored a proper tumor-immune system recognition in response to chemotherapy in MDR cells.

Conclusions: Our work describes a new biochemical effect of omega 3 PUFAs, which can be useful to overcome chemoresistance in MDR colon cancer cells.

Show MeSH
Related in: MedlinePlus