Abstract
Elevated glucose consumption is fundamental to cancer, but selectively targeting this pathway is challenging. We develop a high-throughput assay for measuring glucose consumption and use it to screen non-small-cell lung cancer cell lines against bioactive small molecules. We identify Milciclib that blocks glucose consumption in H460 and H1975, but not in HCC827 or A549 cells, by decreasing SLC2A1 (GLUT1) mRNA and protein levels and by inhibiting glucose transport. Milciclib blocks glucose consumption by targeting cyclin-dependent kinase 7 (CDK7) similar to other CDK7 inhibitors including THZ1 and LDC4297. Enhanced PIK3CA signaling leads to CDK7 phosphorylation, which promotes RNA Polymerase II phosphorylation and transcription. Milciclib, THZ1, and LDC4297 lead to a reduction in RNA Polymerase II phosphorylation on the SLC2A1 promoter. These data indicate that our high-throughput assay can identify compounds that regulate glucose consumption and that CDK7 is a key regulator of glucose consumption in cells with an activated PI3K pathway.
Highlights
Elevated glucose consumption is fundamental to cancer, but selectively targeting this pathway is challenging
Milciclib is an inhibitor of CDK2, CDK4, cyclindependent kinase 7 (CDK7), and TRKA32,33 and in our high-throughput screen we found that it blocks glucose consumption in H460 cells
Since Milciclib, THZ1, and LDC4297 decrease GLUT1 mRNA levels (Fig. 4a; Supplementary Fig. 11), we focused on a potential mechanism through which CDK7 regulates GLUT1 transcription
Summary
Elevated glucose consumption is fundamental to cancer, but selectively targeting this pathway is challenging. THZ1, and LDC4297 lead to a reduction in RNA Polymerase II phosphorylation on the SLC2A1 promoter These data indicate that our high-throughput assay can identify compounds that regulate glucose consumption and that CDK7 is a key regulator of glucose consumption in cells with an activated PI3K pathway. Despite using the same biochemical enzymes as non-transformed cells to consume glucose, use different signaling pathways to regulate these enzymes[20,21,22] Targeting these pathways may represent a strategy to block cancer cell glucose consumption while sparing healthy cells and may provide greater selectivity than directly targeting the enzymes that metabolize glucose. We screened 3555 compounds against A549, H460, and HCC827 non-small-cell lung cancer (NSCLC) cells and identified 97 inhibitors of glucose consumption including the small molecule Milciclib. Milciclib inhibits glucose transport by blocking CDK7 from phosphorylating and activating RNA Polymerase II downstream of activated PIK3CA
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