HnRNP proteins controlled by c-Myc deregulate pyruvate kinase mRNA splicing in cancer


When oxygen is abundant, quiescent cells efficiently extract energy from glucose primarily by oxidative phosphorylation, whereas under the same conditions tumour cells consume glucose more avidly, converting it to lactate. This long-observed phenomenon is known as aerobic glycolysis1, and is important for cell growth2,3. Because aerobic glycolysis is only useful to growing cells, it is tightly regulated in a proliferation-linked manner4. In mammals, this is partly achieved through control of pyruvate kinase isoform expression. The embryonic pyruvate kinase isoform, PKM2, is almost universally re-expressed in cancer2, and promotes aerobic glycolysis, whereas the adult isoform, PKM1, promotes oxidative phosphorylation2. These two isoforms result from mutually exclusive alternative splicing of the PKM pre-mRNA, reflecting inclusion of either exon 9 (PKM1) or exon 10 (PKM2). Here we show that three heterogeneous nuclear ribonucleoprotein (hnRNP) proteins, polypyrimidine tract binding protein (PTB, also known as hnRNPI), hnRNPA1 and hnRNPA2, bind repressively to sequences flanking exon 9, resulting in exon 10 inclusion. We also demonstrate that the oncogenic transcription factor c-Myc upregulates transcription of PTB, hnRNPA1 and hnRNPA2, ensuring a high PKM2/PKM1 ratio. Establishing a relevance to cancer, we show that human gliomas overexpress c-Myc, PTB, hnRNPA1 and hnRNPA2 in a manner that correlates with PKM2 expression. Our results thus define a pathway that regulates an alternative splicing event required for tumour cell proliferation.

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Figure 1: hnRNP proteins bind specifically to sequences flanking E9.
Figure 2: PTB, hnRNPA1 and hnRNPA2 are required for high PKM2/PKM1 mRNA ratios.
Figure 3: Expression of PTB, hnRNPA1, hnRNPA2 and c-Myc correlates with PKM2 expression in C2C12 cells and tumours.
Figure 4: c-Myc upregulates PTB, hnRNPA1 and hnRNPA2 and alters PKM splicing.


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We thank D. Black for BB7 antibody; T. Kashima for hnRNP A1/A2 siRNA; R. Prywes and E. Henckles for C2C12 cells; M. Sheetz and X. Zhang for NIH-3T3 cells; C. Prives, T. Barsotti and L. Biderman for MCF-7 cells, Rb and E2F1 siRNA; R. Dalla-Favera and Q. Shen for anti-c-Myc antibodies and c-Myc expression vector; R. Eisenman for N-Myc antibody; and members of the Manley laboratory for discussions. This work was supported by grants from the Avon Foundation and the NIH.

Author Contributions C.J.D., M.C. and J.L.M. conceived the project and designed experiments, C.J.D. and M.C. carried out experiments, P.C. and M.A. provided tumour samples, and C.J.D., M.C. and J.L.M. interpreted data and wrote the paper.

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Correspondence to James L. Manley.

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David, C., Chen, M., Assanah, M. et al. HnRNP proteins controlled by c-Myc deregulate pyruvate kinase mRNA splicing in cancer. Nature 463, 364–368 (2010).

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