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Lipophilic but not hydrophilic statins selectively induce cell death in gynaecological cancers expressing high levels of HMGCoA reductase.

Kato S, Smalley S, Sadarangani A, Chen-Lin K, Oliva B, Brañes J, Carvajal J, Gejman R, Owen GI, Cuello M - J. Cell. Mol. Med. (2009)

Bottom Line: Statin-sensitive cancers expressed high levels of HMG-CoA reductase compared with resistant cultures.The effect of lipophilic statins was dependent on inhibition of enzymatic activity of HMG-CoA reductase since mevalonate pre-incubation almost completely abrogated the apoptotic effect.In conclusion, lipophilic but not hydrophilic statins induce cell death through activation of extrinsic and intrinsic apoptotic cascades in cancerous cells from the human female genital tract, which express high levels of HMG-CoA reductase.

View Article: PubMed Central - PubMed

Affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.

ABSTRACT
Recent reports have suggested that statins induce cell death in certain epithelial cancers and that patients taking statins to reduce cholesterol levels possess lower cancer incidence. However, little is known about the mechanisms of action of different statins or the effects of these statins in gynaecological malignancies. The apoptotic potential of two lipophilic statins (lovastatin and simvastatin) and one hydrophilic statin (pravastatin) was assessed in cancer cell lines (ovarian, endometrial and cervical) and primary cultured cancerous and normal tissues. Cell viability was studied by MTS assays and apoptosis was confirmed by Western blotting of PARP and flow cytometry. The expressions of key apoptotic cascade proteins were analysed. Our results demonstrate that both lovastatin and simvastatin, but not pravastatin, selectively induced cell death in dose- and time-dependent manner in ovarian, endometrial and cervical cancers. Little or no toxicity was observed with any statin on normal cells. Lipophilic statins induced activation of caspase-8 and -9; BID cleavage, cytochrome C release and PARP cleavage. Statin-sensitive cancers expressed high levels of HMG-CoA reductase compared with resistant cultures. The effect of lipophilic statins was dependent on inhibition of enzymatic activity of HMG-CoA reductase since mevalonate pre-incubation almost completely abrogated the apoptotic effect. Moreover, the apoptotic effect involved the inhibition of synthesis of geranylgeranyl pyrophosphate rather than farnesyl pyrophosphate. In conclusion, lipophilic but not hydrophilic statins induce cell death through activation of extrinsic and intrinsic apoptotic cascades in cancerous cells from the human female genital tract, which express high levels of HMG-CoA reductase. These results promote further investigation in the use of lipophilic statins as anticancer agents in gynaecological malignancies.

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(A) Effect of lipophilic (lovastatin: Lov10; simvastatin: Sim10) statins used at 10 uM for 48 hrs in the presence or absence of vehicle (DMSO), geranylgeranyl (geranyl-pp, 10 uM) or farnesyl (farnesyl-pp, 10 uM) pyrophosphates in two cell lines [A2780 (A) and Hela (C)] and one cancerous primary tissue culture [ca ovary 6 (B)]. Cell viability was measured by MTS assay.
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fig09: (A) Effect of lipophilic (lovastatin: Lov10; simvastatin: Sim10) statins used at 10 uM for 48 hrs in the presence or absence of vehicle (DMSO), geranylgeranyl (geranyl-pp, 10 uM) or farnesyl (farnesyl-pp, 10 uM) pyrophosphates in two cell lines [A2780 (A) and Hela (C)] and one cancerous primary tissue culture [ca ovary 6 (B)]. Cell viability was measured by MTS assay.

Mentions: To confirm that cell death induced by lipophilic statins in gynaecological cancers is due to the decrease in the synthesis of mevalonate (through inhibition of HMGCoA reductase by statins), we analysed if statin-mediated cell death could be rescued by the supplementation of mevalonate in A2780 and Hela cells. In accordance with our theory, we demonstrated that mevalonate supplementation prevented the loss of cell viability induced by statins in A2780 cells (Fig. 8A). Figure 8B shows by immunoblotting the absence of PARP cleavage upon supplementation with mevalonate in both A2780 as well as Hela cells confirming the importance of mevalonate for the sensitivity of these cells to statins. Previous reports in endothelial and lymphoblast cells have suggested that the two isoprenes, farnesyl and geranylgeranyl pyrophosphates, can be involved in the ability of evading cell death of cancerous cells [21, 34]. Both isoprenes are located downstream to mevalonate in the cholesterol pathway. They act as lipophilic anchors on the cell membrane for both attachment and biological activity of small-GTP binding proteins (i.e. Rho family - Rac 1 and Cdc42-, and Ras) and activate other functional proteins involved in both the cell cycle and cell proliferation [35]. In vitro studies in ovarian cancer cells have shown that farnesyl and geranylgeranyl pyrophosphate could revert the effect in cell viability induced by lovastatin [25, 26]. Therefore, we decided to investigate if any of these isoprenes could affect cell death induced by simvastatin in cell lines and primary tissue cultures from gynaecological cancers. As shown in Figure 9, the addition of geranylgeranyl but not farnesyl pyrophosphate almost completely abrogates the effect in cell viability induced by both statins in the A2780 cells and Hela cells. Similar effect was observed with two primary cultures established from ovarian cancer (indicated as ovarian ca 6 in the Fig. 9) and uterine cancer (data not shown).


Lipophilic but not hydrophilic statins selectively induce cell death in gynaecological cancers expressing high levels of HMGCoA reductase.

Kato S, Smalley S, Sadarangani A, Chen-Lin K, Oliva B, Brañes J, Carvajal J, Gejman R, Owen GI, Cuello M - J. Cell. Mol. Med. (2009)

(A) Effect of lipophilic (lovastatin: Lov10; simvastatin: Sim10) statins used at 10 uM for 48 hrs in the presence or absence of vehicle (DMSO), geranylgeranyl (geranyl-pp, 10 uM) or farnesyl (farnesyl-pp, 10 uM) pyrophosphates in two cell lines [A2780 (A) and Hela (C)] and one cancerous primary tissue culture [ca ovary 6 (B)]. Cell viability was measured by MTS assay.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3822754&req=5

fig09: (A) Effect of lipophilic (lovastatin: Lov10; simvastatin: Sim10) statins used at 10 uM for 48 hrs in the presence or absence of vehicle (DMSO), geranylgeranyl (geranyl-pp, 10 uM) or farnesyl (farnesyl-pp, 10 uM) pyrophosphates in two cell lines [A2780 (A) and Hela (C)] and one cancerous primary tissue culture [ca ovary 6 (B)]. Cell viability was measured by MTS assay.
Mentions: To confirm that cell death induced by lipophilic statins in gynaecological cancers is due to the decrease in the synthesis of mevalonate (through inhibition of HMGCoA reductase by statins), we analysed if statin-mediated cell death could be rescued by the supplementation of mevalonate in A2780 and Hela cells. In accordance with our theory, we demonstrated that mevalonate supplementation prevented the loss of cell viability induced by statins in A2780 cells (Fig. 8A). Figure 8B shows by immunoblotting the absence of PARP cleavage upon supplementation with mevalonate in both A2780 as well as Hela cells confirming the importance of mevalonate for the sensitivity of these cells to statins. Previous reports in endothelial and lymphoblast cells have suggested that the two isoprenes, farnesyl and geranylgeranyl pyrophosphates, can be involved in the ability of evading cell death of cancerous cells [21, 34]. Both isoprenes are located downstream to mevalonate in the cholesterol pathway. They act as lipophilic anchors on the cell membrane for both attachment and biological activity of small-GTP binding proteins (i.e. Rho family - Rac 1 and Cdc42-, and Ras) and activate other functional proteins involved in both the cell cycle and cell proliferation [35]. In vitro studies in ovarian cancer cells have shown that farnesyl and geranylgeranyl pyrophosphate could revert the effect in cell viability induced by lovastatin [25, 26]. Therefore, we decided to investigate if any of these isoprenes could affect cell death induced by simvastatin in cell lines and primary tissue cultures from gynaecological cancers. As shown in Figure 9, the addition of geranylgeranyl but not farnesyl pyrophosphate almost completely abrogates the effect in cell viability induced by both statins in the A2780 cells and Hela cells. Similar effect was observed with two primary cultures established from ovarian cancer (indicated as ovarian ca 6 in the Fig. 9) and uterine cancer (data not shown).

Bottom Line: Statin-sensitive cancers expressed high levels of HMG-CoA reductase compared with resistant cultures.The effect of lipophilic statins was dependent on inhibition of enzymatic activity of HMG-CoA reductase since mevalonate pre-incubation almost completely abrogated the apoptotic effect.In conclusion, lipophilic but not hydrophilic statins induce cell death through activation of extrinsic and intrinsic apoptotic cascades in cancerous cells from the human female genital tract, which express high levels of HMG-CoA reductase.

View Article: PubMed Central - PubMed

Affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.

ABSTRACT
Recent reports have suggested that statins induce cell death in certain epithelial cancers and that patients taking statins to reduce cholesterol levels possess lower cancer incidence. However, little is known about the mechanisms of action of different statins or the effects of these statins in gynaecological malignancies. The apoptotic potential of two lipophilic statins (lovastatin and simvastatin) and one hydrophilic statin (pravastatin) was assessed in cancer cell lines (ovarian, endometrial and cervical) and primary cultured cancerous and normal tissues. Cell viability was studied by MTS assays and apoptosis was confirmed by Western blotting of PARP and flow cytometry. The expressions of key apoptotic cascade proteins were analysed. Our results demonstrate that both lovastatin and simvastatin, but not pravastatin, selectively induced cell death in dose- and time-dependent manner in ovarian, endometrial and cervical cancers. Little or no toxicity was observed with any statin on normal cells. Lipophilic statins induced activation of caspase-8 and -9; BID cleavage, cytochrome C release and PARP cleavage. Statin-sensitive cancers expressed high levels of HMG-CoA reductase compared with resistant cultures. The effect of lipophilic statins was dependent on inhibition of enzymatic activity of HMG-CoA reductase since mevalonate pre-incubation almost completely abrogated the apoptotic effect. Moreover, the apoptotic effect involved the inhibition of synthesis of geranylgeranyl pyrophosphate rather than farnesyl pyrophosphate. In conclusion, lipophilic but not hydrophilic statins induce cell death through activation of extrinsic and intrinsic apoptotic cascades in cancerous cells from the human female genital tract, which express high levels of HMG-CoA reductase. These results promote further investigation in the use of lipophilic statins as anticancer agents in gynaecological malignancies.

Show MeSH
Related in: MedlinePlus