Histidine phosphorylation, the so-called hidden phosphoproteome, is a poorly characterized post-translational modification of proteins1,2. Here we describe a role of histidine phosphorylation in tumorigenesis. Proteomic analysis of 12 tumours from an mTOR-driven hepatocellular carcinoma mouse model revealed that NME1 and NME2, the only known mammalian histidine kinases, were upregulated. Conversely, expression of the putative histidine phosphatase LHPP was downregulated specifically in the tumours. We demonstrate that LHPP is indeed a protein histidine phosphatase. Consistent with these observations, global histidine phosphorylation was significantly upregulated in the liver tumours. Sustained, hepatic expression of LHPP in the hepatocellular carcinoma mouse model reduced tumour burden and prevented the loss of liver function. Finally, in patients with hepatocellular carcinoma, low expression of LHPP correlated with increased tumour severity and reduced overall survival. Thus, LHPP is a protein histidine phosphatase and tumour suppressor, suggesting that deregulated histidine phosphorylation is oncogenic.
M.N.H. acknowledges the Louis Jeantet Foundation, the Swiss National Science Foundation, SystemsX.ch, and the European Research Council (MERiC). T.H. acknowledges USPHS grants CA080100, CA082683 and CA194584 from the NCI. T.H. is an American Cancer Society Professor, and holds the Renato Dulbecco Chair in Cancer Research. S.P. acknowledges the Swiss National Science Foundation (Ambizione grant number PZ00P3_168165).
Extended data figures
This file contains Supplementary Table 1: Identification of proteins enriched with histidine phosphorylation in tumours. 1173 proteins were detected and enriched (min 2-fold) in 2 out of 2 tumours (100%), or 3 out of 3 tumours (100%), or 3/4 out of 4 tumours (75%, 100%).
This file contains Supplementary Table 2: Identification of proteins enriched with histidine phosphorylation in control tissue. 823 proteins were detected and enriched (min 2-fold) in 2 out of 2 control tissues (100%), or 3 out of 3 control tissues (100%), or 3/4 out of 4 control tissues (75%, 100%).
This file contains Supplementary Table 3: Differentially enriched proteins with histidine phosphorylation in tumours 236 proteins were detected and enriched (min 2-fold) in 2 out of 2 experiments (100%), or 3 out of 3 experiments (100%), or 3/4 out of 4 experiments (75%, 100%).
This file contains Supplementary Table 4: Identification of proteins whose histidine phosphorylation decreased upon LHPP re-expression. Nine proteins (with a log fold change of 1.7) and 17 proteins (with a log fold change of 1.4) were more abundant in immunoprecipitates from CB1 cells lacking LHPP in at least 50% of the detections (out of 5 experiments).
This file contains Supplementary Table 5: List of mutations detected in LHPP. It shows a list of LHPP mutations detected from TCGA and ICGC portal. Deleterious mutations are highlighted in red.