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Retinoid and thiazolidinedione therapies in melanoma: an analysis of differential response based on nuclear hormone receptor expression.

Klopper JP, Sharma V, Berenz A, Hays WR, Loi M, Pugazhenthi U, Said S, Haugen BR - Mol. Cancer (2009)

Bottom Line: A375(DRO) tumor growth was significantly inhibited by either ligand alone and the combination had an additive effect.A375(DRO) sublines resistant to rexinoid, TZD and combination were generated and all three sublines had reduced PPARgamma expression but preserved RXR expression. shRNA knockdown of PPARgamma or RXRgamma attenuated the rexinoid, TZD and combination ligand-mediated decreased proliferation in A375(DRO) cells.Rexinoid (LGD1069) and retinoid (TTNPB) treatment of M14(5-16) cells resulted in decreased proliferation that was additive with combination of both rexinoid and retinoid. shRNA knockdown of RXRgamma resulted in a decreased response to either ligand.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Colorado Denver, Aurora, CO, USA. joshua.klopper@ucdenver.edu

ABSTRACT

Background: Metastatic melanoma has a high mortality rate and suboptimal therapeutic options. Molecular targeting may be beneficial using the rexinoid LGD1069, a retinoid x receptor selective agonist, and thiazolidinediones (TZD), PPARgamma selective ligands, as novel treatments.

Results: Mouse xenograft models with human melanoma cell lines [A375(DRO) or M14(5-16)] were treated for 4 weeks with daily vehicle, RXR agonist (rexinoid, LGD1069, 30 mg/kg/d), PPARgamma agonist (TZD, rosiglitazone, 10 mg/kg/d) or combination. A375(DRO) tumor growth was significantly inhibited by either ligand alone and the combination had an additive effect. M14(5-16) tumors only responded to LGD1069 100 mg/kg/day. A375(DRO) sublines resistant to rexinoid, TZD and combination were generated and all three sublines had reduced PPARgamma expression but preserved RXR expression. shRNA knockdown of PPARgamma or RXRgamma attenuated the rexinoid, TZD and combination ligand-mediated decreased proliferation in A375(DRO) cells. Rexinoid (LGD1069) and retinoid (TTNPB) treatment of M14(5-16) cells resulted in decreased proliferation that was additive with combination of both rexinoid and retinoid. shRNA knockdown of RXRgamma resulted in a decreased response to either ligand.

Conclusion: A375 (DRO) melanoma cell growth is inhibited by rexinoid and TZD treatment, and this response is dependent on RXR and PPARgamma receptor expression. M14 (5-16) melanoma cell growth is inhibited by rexinoid and retinoid treatment, and this response is dependent on RXR expression. These findings may help guide molecular-based treatment strategies in melanoma and provide insight for mechanisms of resistance to nuclear receptor targeted therapies in certain cancers.

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Proliferation of resistant A375(DRO) cells: "resistant" cells were grown in 2% fetal bovine serum RPMI in the presence of 1 μmol/L of LGD1069, TZD or the combination for 9 days. Cell growth was analyzed using a nonradioactive cell proliferation assay. Proliferation was compared to that of cells grown in volume equivalent vehicle (DMSO – represented by the line) and resistant sublines were compared to the DMSO R control to assess the attenuation of response to receptor specific ligands. Proliferation was statistically significantly attenuated compared to the control DMSO R in all resistant cell lines and condition save for combination therapy in TZD R (p < 0.03). Columns, mean; bars, SEM.
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Figure 2: Proliferation of resistant A375(DRO) cells: "resistant" cells were grown in 2% fetal bovine serum RPMI in the presence of 1 μmol/L of LGD1069, TZD or the combination for 9 days. Cell growth was analyzed using a nonradioactive cell proliferation assay. Proliferation was compared to that of cells grown in volume equivalent vehicle (DMSO – represented by the line) and resistant sublines were compared to the DMSO R control to assess the attenuation of response to receptor specific ligands. Proliferation was statistically significantly attenuated compared to the control DMSO R in all resistant cell lines and condition save for combination therapy in TZD R (p < 0.03). Columns, mean; bars, SEM.

Mentions: To confirm drug resistance, we performed proliferation assays with 1 μM of each ligand alone or in combination (10 × higher drug concentration than the final growing conditions of 100 nM). We first confirmed that the control A375(DRO) cells that were grown in volume equivalent vehicle had a similar response to early passage A375(DRO) cells exposed to volume equivalent vehicle (DMSO) (data not shown). Figure 2 shows that LGD1069 R cells were resistant to growth inhibition by 1 μM LGD1069 as expected, but surprisingly also lost the growth inhibitory effect of TZD, despite no exposure to TZD. These LGD1069 R cells also had significant attenuation of growth inhibition by LGD/TZD combination. TZD R cells attenuated growth inhibition by LGD and TZD alone compared to DMSO R cells. LGD/TZD R cells were completely resistant to growth inhibition by all conditions as was expected. The attenuation of the treatment effect to all treatment conditions compared to the control cell line (DMSO R) was significant (p < 0.03) except for the TZD R subline treated with combination LGD/TZD (fig 2).


Retinoid and thiazolidinedione therapies in melanoma: an analysis of differential response based on nuclear hormone receptor expression.

Klopper JP, Sharma V, Berenz A, Hays WR, Loi M, Pugazhenthi U, Said S, Haugen BR - Mol. Cancer (2009)

Proliferation of resistant A375(DRO) cells: "resistant" cells were grown in 2% fetal bovine serum RPMI in the presence of 1 μmol/L of LGD1069, TZD or the combination for 9 days. Cell growth was analyzed using a nonradioactive cell proliferation assay. Proliferation was compared to that of cells grown in volume equivalent vehicle (DMSO – represented by the line) and resistant sublines were compared to the DMSO R control to assess the attenuation of response to receptor specific ligands. Proliferation was statistically significantly attenuated compared to the control DMSO R in all resistant cell lines and condition save for combination therapy in TZD R (p < 0.03). Columns, mean; bars, SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2654861&req=5

Figure 2: Proliferation of resistant A375(DRO) cells: "resistant" cells were grown in 2% fetal bovine serum RPMI in the presence of 1 μmol/L of LGD1069, TZD or the combination for 9 days. Cell growth was analyzed using a nonradioactive cell proliferation assay. Proliferation was compared to that of cells grown in volume equivalent vehicle (DMSO – represented by the line) and resistant sublines were compared to the DMSO R control to assess the attenuation of response to receptor specific ligands. Proliferation was statistically significantly attenuated compared to the control DMSO R in all resistant cell lines and condition save for combination therapy in TZD R (p < 0.03). Columns, mean; bars, SEM.
Mentions: To confirm drug resistance, we performed proliferation assays with 1 μM of each ligand alone or in combination (10 × higher drug concentration than the final growing conditions of 100 nM). We first confirmed that the control A375(DRO) cells that were grown in volume equivalent vehicle had a similar response to early passage A375(DRO) cells exposed to volume equivalent vehicle (DMSO) (data not shown). Figure 2 shows that LGD1069 R cells were resistant to growth inhibition by 1 μM LGD1069 as expected, but surprisingly also lost the growth inhibitory effect of TZD, despite no exposure to TZD. These LGD1069 R cells also had significant attenuation of growth inhibition by LGD/TZD combination. TZD R cells attenuated growth inhibition by LGD and TZD alone compared to DMSO R cells. LGD/TZD R cells were completely resistant to growth inhibition by all conditions as was expected. The attenuation of the treatment effect to all treatment conditions compared to the control cell line (DMSO R) was significant (p < 0.03) except for the TZD R subline treated with combination LGD/TZD (fig 2).

Bottom Line: A375(DRO) tumor growth was significantly inhibited by either ligand alone and the combination had an additive effect.A375(DRO) sublines resistant to rexinoid, TZD and combination were generated and all three sublines had reduced PPARgamma expression but preserved RXR expression. shRNA knockdown of PPARgamma or RXRgamma attenuated the rexinoid, TZD and combination ligand-mediated decreased proliferation in A375(DRO) cells.Rexinoid (LGD1069) and retinoid (TTNPB) treatment of M14(5-16) cells resulted in decreased proliferation that was additive with combination of both rexinoid and retinoid. shRNA knockdown of RXRgamma resulted in a decreased response to either ligand.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Colorado Denver, Aurora, CO, USA. joshua.klopper@ucdenver.edu

ABSTRACT

Background: Metastatic melanoma has a high mortality rate and suboptimal therapeutic options. Molecular targeting may be beneficial using the rexinoid LGD1069, a retinoid x receptor selective agonist, and thiazolidinediones (TZD), PPARgamma selective ligands, as novel treatments.

Results: Mouse xenograft models with human melanoma cell lines [A375(DRO) or M14(5-16)] were treated for 4 weeks with daily vehicle, RXR agonist (rexinoid, LGD1069, 30 mg/kg/d), PPARgamma agonist (TZD, rosiglitazone, 10 mg/kg/d) or combination. A375(DRO) tumor growth was significantly inhibited by either ligand alone and the combination had an additive effect. M14(5-16) tumors only responded to LGD1069 100 mg/kg/day. A375(DRO) sublines resistant to rexinoid, TZD and combination were generated and all three sublines had reduced PPARgamma expression but preserved RXR expression. shRNA knockdown of PPARgamma or RXRgamma attenuated the rexinoid, TZD and combination ligand-mediated decreased proliferation in A375(DRO) cells. Rexinoid (LGD1069) and retinoid (TTNPB) treatment of M14(5-16) cells resulted in decreased proliferation that was additive with combination of both rexinoid and retinoid. shRNA knockdown of RXRgamma resulted in a decreased response to either ligand.

Conclusion: A375 (DRO) melanoma cell growth is inhibited by rexinoid and TZD treatment, and this response is dependent on RXR and PPARgamma receptor expression. M14 (5-16) melanoma cell growth is inhibited by rexinoid and retinoid treatment, and this response is dependent on RXR expression. These findings may help guide molecular-based treatment strategies in melanoma and provide insight for mechanisms of resistance to nuclear receptor targeted therapies in certain cancers.

Show MeSH
Related in: MedlinePlus