The mitochondrial serine hydroxymethyltransferase SHMT2, which catalyzes the rate-limiting step in serine catabolism, drives cancer cell proliferation, but how this role is regulated is undefined. Here, we report that the sirtuin SIRT5 desuccinylates SHMT2 to increase its activity and drive serine catabolism in tumor cells. SIRT5 interaction directly mediated desuccinylation of lysine 280 on SHMT2, which was crucial for activating its enzymatic activity. Conversely, hypersuccinylation of SHMT2 at lysine 280 was sufficient to inhibit its enzymatic activity and downregulate tumor cell growth in vitro and in vivo. Notably, SIRT5 inactivation led to SHMT2 enzymatic downregulation and to abrogated cell growth under metabolic stress. Our results reveal that SHMT2 desuccinylation is a pivotal signal in cancer cells to adapt serine metabolic processes for rapid growth, and they highlight SIRT5 as a candidate target for suppressing serine catabolism as a strategy to block tumor growth.Significance: These findings reveal a novel mechanism for controlling cancer cell proliferation by blocking serine catabolism, as a general strategy to impede tumor growth. Cancer Res; 78(2); 372-86.Ó2017 AACR.

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MXene-derived TiO2/RGO composite was designed and synthesized by the hydrothermal process as a universal anode for Li-ion and K-ion batteries.

Effective reversal of tumor immunosuppression is of critical importance in cancer therapy. A multifunctional delivery vector that can effectively deliver CRISPR‐Cas9 plasmid for β‐catenin knockout to reverse tumor immunosuppression is constructed. The multi‐functionalized delivery vector is decorated with aptamer‐conjugated hyaluronic acid and peptide‐conjugated hyaluronic acid to combine the tumor cell/nuclear targeting function of AS1411 with the cell penetrating/nuclear translocation function of TAT‐NLS. Due to the significantly enhanced plasmid enrichment in malignant cell nuclei, the genome editing system can induce effective β‐catenin knockout and suppress Wnt/β‐catenin pathway, resulting in notably downregulated proteins involved in tumor progression and immunosuppression. Programmed death‐ligand 1 (PD‐L1) downregulation in edited tumor cells not only releases the PD‐1/PD‐L1 brake to improve the cancer killing capability of CD8+ T cells, but also enhances antitumor immune responses of immune cells. This provides a facile strategy to reverse tumor immunosuppression and to restore immunosurveillance and activate anti‐tumor immunity.

Highlights d Quantitative acetylomics reveals hyperacetylated proteins upon nutrition starvation d Multiple cellular stresses result in p300-dependent PHF5A K29 acetylation d PHF5A K29 acetylation enhances KDM3A expression by stabilizing its mRNA d PHF5A acetylation and KDM3A upregulation predict poor prognosis in colon cancer