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Selective Targeting of CTNBB1-, KRAS- or MYC-Driven Cell Growth by Combinations of Existing Drugs.

Uitdehaag JC, de Roos JA, van Doornmalen AM, Prinsen MB, Spijkers-Hagelstein JA, de Vetter JR, de Man J, Buijsman RC, Zaman GJ - PLoS ONE (2015)

Bottom Line: We demonstrate that the Wnt-pathway inhibitor ICG-001 and trametinib acted synergistically in Wnt-pathway-mutant cell lines.The ERBB2 inhibitor TAK-165 was synergistic with trametinib in KRAS-mutant cell lines.The EGFR/ERBB2 inhibitor neratinib acted synergistically with the spindle poison docetaxel and with the Aurora kinase inhibitor GSK-1070916 in cell lines with MYC amplification.

View Article: PubMed Central - PubMed

Affiliation: Netherlands Translational Research Center B.V., Oss, The Netherlands.

ABSTRACT
The aim of combination drug treatment in cancer therapy is to improve response rate and to decrease the probability of the development of drug resistance. Preferably, drug combinations are synergistic rather than additive, and, ideally, drug combinations work synergistically only in cancer cells and not in non-malignant cells. We have developed a workflow to identify such targeted synergies, and applied this approach to selectively inhibit the proliferation of cell lines with mutations in genes that are difficult to modulate with small molecules. The approach is based on curve shift analysis, which we demonstrate is a more robust method of determining synergy than combination matrix screening with Bliss-scoring. We show that the MEK inhibitor trametinib is more synergistic in combination with the BRAF inhibitor dabrafenib than with vemurafenib, another BRAF inhibitor. In addition, we show that the combination of MEK and BRAF inhibitors is synergistic in BRAF-mutant melanoma cells, and additive or antagonistic in, respectively, BRAF-wild type melanoma cells and non-malignant fibroblasts. This combination exemplifies that synergistic action of drugs can depend on cancer genotype. Next, we used curve shift analysis to identify new drug combinations that specifically inhibit cancer cell proliferation driven by difficult-to-drug cancer genes. Combination studies were performed with compounds that as single agents showed preference for inhibition of cancer cells with mutations in either the CTNNB1 gene (coding for β-catenin), KRAS, or cancer cells expressing increased copy numbers of MYC. We demonstrate that the Wnt-pathway inhibitor ICG-001 and trametinib acted synergistically in Wnt-pathway-mutant cell lines. The ERBB2 inhibitor TAK-165 was synergistic with trametinib in KRAS-mutant cell lines. The EGFR/ERBB2 inhibitor neratinib acted synergistically with the spindle poison docetaxel and with the Aurora kinase inhibitor GSK-1070916 in cell lines with MYC amplification. Our approach can therefore efficiently discover novel drug combinations that selectively target cancer genes.

No MeSH data available.


Related in: MedlinePlus

Synergy between EGFR and BRAF inhibitors in a colon carcinoma line.A: Curve shift experiment of the EGFR inhibitor gefitinib (blue) and the BRAF inhibitor dabrafenib (green) in a proliferation assay of the BRAF-mutant WiDr colon carcinoma cell line. Yellow, red, orange are mixture curves as described in Fig 1. B: as panel A but with vemurafenib (green) as BRAF inhibitor. In panel A, there is clear synergy between the two drugs, in panel B, there is less synergy.
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pone.0125021.g004: Synergy between EGFR and BRAF inhibitors in a colon carcinoma line.A: Curve shift experiment of the EGFR inhibitor gefitinib (blue) and the BRAF inhibitor dabrafenib (green) in a proliferation assay of the BRAF-mutant WiDr colon carcinoma cell line. Yellow, red, orange are mixture curves as described in Fig 1. B: as panel A but with vemurafenib (green) as BRAF inhibitor. In panel A, there is clear synergy between the two drugs, in panel B, there is less synergy.

Mentions: Recently, it was suggested that the growth of BRAF-mutant colon carcinoma cell lines can be inhibited by combining a BRAF inhibitor with an EGFR inhibitor, which both were suggested to be inactive as single agents [29]. As this seemed an interesting example of a synergistic interaction that only takes place in a particular cancer cell type (i.e. BRAF-mutant, EGFR overexpressing colon cancer cell lines), we performed curve shift assays with the EGFR inhibitor gefitinib and the BRAF inhibitors vemurafenib and dabrafenib, in proliferation assays with the BRAF-mutant colon carcinoma WiDr cell line (Fig 4). Although we can confirm the poor single agent activities of gefitinib (IC50 = 8 μM), vemurafenib as well as dabrafenib show a clear dose-response curve in the WiDr cell proliferation assay, with IC50s of 900 nM and 76 nM, respectively (Fig 4). At the highest concentrations, the BRAF inhibitors have only partial efficacy as single agents, whereas in the combinations, when mixed with a relatively small amount of EGFR inhibitor (such as in the dose ratio of 4:1), full efficacy is obtained (Fig 4). Although the mixture curves are not shifted leftward, the CI values indicate synergy, particulary for gefitinib and vemurafenib (Fig 4).


Selective Targeting of CTNBB1-, KRAS- or MYC-Driven Cell Growth by Combinations of Existing Drugs.

Uitdehaag JC, de Roos JA, van Doornmalen AM, Prinsen MB, Spijkers-Hagelstein JA, de Vetter JR, de Man J, Buijsman RC, Zaman GJ - PLoS ONE (2015)

Synergy between EGFR and BRAF inhibitors in a colon carcinoma line.A: Curve shift experiment of the EGFR inhibitor gefitinib (blue) and the BRAF inhibitor dabrafenib (green) in a proliferation assay of the BRAF-mutant WiDr colon carcinoma cell line. Yellow, red, orange are mixture curves as described in Fig 1. B: as panel A but with vemurafenib (green) as BRAF inhibitor. In panel A, there is clear synergy between the two drugs, in panel B, there is less synergy.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4446296&req=5

pone.0125021.g004: Synergy between EGFR and BRAF inhibitors in a colon carcinoma line.A: Curve shift experiment of the EGFR inhibitor gefitinib (blue) and the BRAF inhibitor dabrafenib (green) in a proliferation assay of the BRAF-mutant WiDr colon carcinoma cell line. Yellow, red, orange are mixture curves as described in Fig 1. B: as panel A but with vemurafenib (green) as BRAF inhibitor. In panel A, there is clear synergy between the two drugs, in panel B, there is less synergy.
Mentions: Recently, it was suggested that the growth of BRAF-mutant colon carcinoma cell lines can be inhibited by combining a BRAF inhibitor with an EGFR inhibitor, which both were suggested to be inactive as single agents [29]. As this seemed an interesting example of a synergistic interaction that only takes place in a particular cancer cell type (i.e. BRAF-mutant, EGFR overexpressing colon cancer cell lines), we performed curve shift assays with the EGFR inhibitor gefitinib and the BRAF inhibitors vemurafenib and dabrafenib, in proliferation assays with the BRAF-mutant colon carcinoma WiDr cell line (Fig 4). Although we can confirm the poor single agent activities of gefitinib (IC50 = 8 μM), vemurafenib as well as dabrafenib show a clear dose-response curve in the WiDr cell proliferation assay, with IC50s of 900 nM and 76 nM, respectively (Fig 4). At the highest concentrations, the BRAF inhibitors have only partial efficacy as single agents, whereas in the combinations, when mixed with a relatively small amount of EGFR inhibitor (such as in the dose ratio of 4:1), full efficacy is obtained (Fig 4). Although the mixture curves are not shifted leftward, the CI values indicate synergy, particulary for gefitinib and vemurafenib (Fig 4).

Bottom Line: We demonstrate that the Wnt-pathway inhibitor ICG-001 and trametinib acted synergistically in Wnt-pathway-mutant cell lines.The ERBB2 inhibitor TAK-165 was synergistic with trametinib in KRAS-mutant cell lines.The EGFR/ERBB2 inhibitor neratinib acted synergistically with the spindle poison docetaxel and with the Aurora kinase inhibitor GSK-1070916 in cell lines with MYC amplification.

View Article: PubMed Central - PubMed

Affiliation: Netherlands Translational Research Center B.V., Oss, The Netherlands.

ABSTRACT
The aim of combination drug treatment in cancer therapy is to improve response rate and to decrease the probability of the development of drug resistance. Preferably, drug combinations are synergistic rather than additive, and, ideally, drug combinations work synergistically only in cancer cells and not in non-malignant cells. We have developed a workflow to identify such targeted synergies, and applied this approach to selectively inhibit the proliferation of cell lines with mutations in genes that are difficult to modulate with small molecules. The approach is based on curve shift analysis, which we demonstrate is a more robust method of determining synergy than combination matrix screening with Bliss-scoring. We show that the MEK inhibitor trametinib is more synergistic in combination with the BRAF inhibitor dabrafenib than with vemurafenib, another BRAF inhibitor. In addition, we show that the combination of MEK and BRAF inhibitors is synergistic in BRAF-mutant melanoma cells, and additive or antagonistic in, respectively, BRAF-wild type melanoma cells and non-malignant fibroblasts. This combination exemplifies that synergistic action of drugs can depend on cancer genotype. Next, we used curve shift analysis to identify new drug combinations that specifically inhibit cancer cell proliferation driven by difficult-to-drug cancer genes. Combination studies were performed with compounds that as single agents showed preference for inhibition of cancer cells with mutations in either the CTNNB1 gene (coding for β-catenin), KRAS, or cancer cells expressing increased copy numbers of MYC. We demonstrate that the Wnt-pathway inhibitor ICG-001 and trametinib acted synergistically in Wnt-pathway-mutant cell lines. The ERBB2 inhibitor TAK-165 was synergistic with trametinib in KRAS-mutant cell lines. The EGFR/ERBB2 inhibitor neratinib acted synergistically with the spindle poison docetaxel and with the Aurora kinase inhibitor GSK-1070916 in cell lines with MYC amplification. Our approach can therefore efficiently discover novel drug combinations that selectively target cancer genes.

No MeSH data available.


Related in: MedlinePlus