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Multiple myeloma acquires resistance to EGFR inhibitor via induction of pentose phosphate pathway.

Chen Y, Huang R, Ding J, Ji D, Song B, Yuan L, Chang H, Chen G - Sci Rep (2015)

Bottom Line: The moderate inhibitory effect was conferred by induction of pentose phosphate pathway (PPP) when cells were treated with Gefitinib, the EGFR inhibitor.Combination of Gefitinib with PPP inhibitor 6AN effected synergistically in triple-WT cells.Our results contributed to the individualized targeted therapy with EGFR inhibitors in MM.

View Article: PubMed Central - PubMed

Affiliation: Department of Haematology, The First Affiliated Hospital of Nanchang University, Nanchang 330006, China.

ABSTRACT
Multiple myeloma (MM) was characterized by frequent mutations in KRAS/NRAS/BRAF within the EGFR pathway that could induce resistance to EGFR inhibitors. We here report that EGFR inhibition solely exhibited moderate inhibition in KRAS/NRAS/BRAF wildtype (triple-WT) MM cells, whilst had no effect in myeloma cells with any of the mutated genes. The moderate inhibitory effect was conferred by induction of pentose phosphate pathway (PPP) when cells were treated with Gefitinib, the EGFR inhibitor. Combination of Gefitinib with PPP inhibitor 6AN effected synergistically in triple-WT cells. The inhibition could be restored by addition of NADPH. Dual EGFR/ERBB2 inhibitor Afatinib also exhibited similar effects. Further genetic silencing of EGFR, ERBB2 and mTOR indicated that major effect conferred by ERBB2 was via convergence to EGFR pathway in MM. Our results contributed to the individualized targeted therapy with EGFR inhibitors in MM.

No MeSH data available.


Related in: MedlinePlus

EGFR inhibitor was effective for triple WT MM cells.A) Gefinitib (5 μM) exhibited moderate inhibition in NRAS WT myeloma cells but not in mutated cells; B) Mutated NRAS was able to activate downstream effectors without EGFR signalling; C) metabolic shift of NRAS WT myeloma cells (LP-1) treated or untreated with Gefitinib (5 μM) for 24 h. Heatmap showing top changed metabolites between groups (each column representing a replicate within group, n = 4). D) MSEA showing significant change in metabolites within pentose phosphate pathway with E) representative metabolite levels in LP-1 cells.
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f2: EGFR inhibitor was effective for triple WT MM cells.A) Gefinitib (5 μM) exhibited moderate inhibition in NRAS WT myeloma cells but not in mutated cells; B) Mutated NRAS was able to activate downstream effectors without EGFR signalling; C) metabolic shift of NRAS WT myeloma cells (LP-1) treated or untreated with Gefitinib (5 μM) for 24 h. Heatmap showing top changed metabolites between groups (each column representing a replicate within group, n = 4). D) MSEA showing significant change in metabolites within pentose phosphate pathway with E) representative metabolite levels in LP-1 cells.

Mentions: Though EGFR inhibitors have shown promise in the clinical practice against some cancers, adaptive resistance remains a major problem. We therefore tended to study the metabolic shift in myeloma cells with KRAS/NRAS/BRAF WT background in response to EGFR inhibition, which was expected to confer primary efficacy. As expected, NRAS Mut cells were primarily resistant to EGFR inhibition, compared with NRAS WT cells (Fig. 2A). The NRAS Mut cells were able to activate downstream elements without EGFR signalling (Fig. 2B). Similar results were also obtained in cells with different KRAS and BRAF status (Suppl. Fig. 2A–B). Nonetheless, inhibitory effect upon KRAS/NRAS/BRAF WT cells was not lasting, and cells were not dying in the presence of EGFR inhibition (data not shown). We thus performed metabolic profiling in KRAS/NRAS/BRAF WT (triple WT) cells treated or untreated with Gefitinib and found significant increased metabolites from the pentose phosphate pathway (PPP) in cells with EGFR inhibition (Fig. 2C–E). Such metabolic shift was not seen in KRAS/NRAS/BRAF mutated cells with EGFR inhibition (Suppl. Fig. 2C). In the confirmation assays, we noticed increased glucose uptake and unchanged lactate secretion in NRAS WT cells and both substances unchanged in NRAS Mut cells (Fig. 3A). Similar results were also recapitulated in cells with genetic silencing using 2 shRNAs against EGFR (Fig. 3B). In accordance, cellular oxygen consumption was not notably changed in WT cells treated with Gefitinib (Fig. 3C). Here we provided evidence that EGFR inhibition, even in theoretically selected cells, could not provide lasting effects due to adaptive metabolic shift to PPP.


Multiple myeloma acquires resistance to EGFR inhibitor via induction of pentose phosphate pathway.

Chen Y, Huang R, Ding J, Ji D, Song B, Yuan L, Chang H, Chen G - Sci Rep (2015)

EGFR inhibitor was effective for triple WT MM cells.A) Gefinitib (5 μM) exhibited moderate inhibition in NRAS WT myeloma cells but not in mutated cells; B) Mutated NRAS was able to activate downstream effectors without EGFR signalling; C) metabolic shift of NRAS WT myeloma cells (LP-1) treated or untreated with Gefitinib (5 μM) for 24 h. Heatmap showing top changed metabolites between groups (each column representing a replicate within group, n = 4). D) MSEA showing significant change in metabolites within pentose phosphate pathway with E) representative metabolite levels in LP-1 cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4403500&req=5

f2: EGFR inhibitor was effective for triple WT MM cells.A) Gefinitib (5 μM) exhibited moderate inhibition in NRAS WT myeloma cells but not in mutated cells; B) Mutated NRAS was able to activate downstream effectors without EGFR signalling; C) metabolic shift of NRAS WT myeloma cells (LP-1) treated or untreated with Gefitinib (5 μM) for 24 h. Heatmap showing top changed metabolites between groups (each column representing a replicate within group, n = 4). D) MSEA showing significant change in metabolites within pentose phosphate pathway with E) representative metabolite levels in LP-1 cells.
Mentions: Though EGFR inhibitors have shown promise in the clinical practice against some cancers, adaptive resistance remains a major problem. We therefore tended to study the metabolic shift in myeloma cells with KRAS/NRAS/BRAF WT background in response to EGFR inhibition, which was expected to confer primary efficacy. As expected, NRAS Mut cells were primarily resistant to EGFR inhibition, compared with NRAS WT cells (Fig. 2A). The NRAS Mut cells were able to activate downstream elements without EGFR signalling (Fig. 2B). Similar results were also obtained in cells with different KRAS and BRAF status (Suppl. Fig. 2A–B). Nonetheless, inhibitory effect upon KRAS/NRAS/BRAF WT cells was not lasting, and cells were not dying in the presence of EGFR inhibition (data not shown). We thus performed metabolic profiling in KRAS/NRAS/BRAF WT (triple WT) cells treated or untreated with Gefitinib and found significant increased metabolites from the pentose phosphate pathway (PPP) in cells with EGFR inhibition (Fig. 2C–E). Such metabolic shift was not seen in KRAS/NRAS/BRAF mutated cells with EGFR inhibition (Suppl. Fig. 2C). In the confirmation assays, we noticed increased glucose uptake and unchanged lactate secretion in NRAS WT cells and both substances unchanged in NRAS Mut cells (Fig. 3A). Similar results were also recapitulated in cells with genetic silencing using 2 shRNAs against EGFR (Fig. 3B). In accordance, cellular oxygen consumption was not notably changed in WT cells treated with Gefitinib (Fig. 3C). Here we provided evidence that EGFR inhibition, even in theoretically selected cells, could not provide lasting effects due to adaptive metabolic shift to PPP.

Bottom Line: The moderate inhibitory effect was conferred by induction of pentose phosphate pathway (PPP) when cells were treated with Gefitinib, the EGFR inhibitor.Combination of Gefitinib with PPP inhibitor 6AN effected synergistically in triple-WT cells.Our results contributed to the individualized targeted therapy with EGFR inhibitors in MM.

View Article: PubMed Central - PubMed

Affiliation: Department of Haematology, The First Affiliated Hospital of Nanchang University, Nanchang 330006, China.

ABSTRACT
Multiple myeloma (MM) was characterized by frequent mutations in KRAS/NRAS/BRAF within the EGFR pathway that could induce resistance to EGFR inhibitors. We here report that EGFR inhibition solely exhibited moderate inhibition in KRAS/NRAS/BRAF wildtype (triple-WT) MM cells, whilst had no effect in myeloma cells with any of the mutated genes. The moderate inhibitory effect was conferred by induction of pentose phosphate pathway (PPP) when cells were treated with Gefitinib, the EGFR inhibitor. Combination of Gefitinib with PPP inhibitor 6AN effected synergistically in triple-WT cells. The inhibition could be restored by addition of NADPH. Dual EGFR/ERBB2 inhibitor Afatinib also exhibited similar effects. Further genetic silencing of EGFR, ERBB2 and mTOR indicated that major effect conferred by ERBB2 was via convergence to EGFR pathway in MM. Our results contributed to the individualized targeted therapy with EGFR inhibitors in MM.

No MeSH data available.


Related in: MedlinePlus