phosphothreonine and Carcinogenesis

Hyperactivation of YAP has been commonly associated with tumorigenesis, and emerging evidence hints at multilayered Hippo-independent regulations of YAP. In this study, we identified a new MST4-YAP axis, which acts as a noncanonical Hippo signaling pathway that limits stress-induced YAP activation. MST4 kinase directly phosphorylated YAP at Thr83 to block its binding with importin α, therefore leading to YAP cytoplasmic retention and inactivation. Due to a consequential interplay between MST4-mediated YAP phospho-Thr83 signaling and the classical YAP phospho-Ser127 signaling, the phosphorylation level of YAP at Thr83 was correlated to that at Ser127. Mutation of T83E mimicking MST4-mediated alternative signaling restrained the activity of both wild-type YAP and its S127A mutant mimicking loss of classical Hippo signal. Depletion of MST4 in mice promoted gastric tumorigenesis with diminished Thr83 phosphorylation and hyperactivation of YAP. Moreover, loss of MST4-YAP signaling was associated with poor prognosis of human gastric cancer. Collectively, our study uncovered a noncanonical MST4-YAP signaling axis essential for suppressing gastric tumorigenesis.

Topics: Active Transport, Cell Nucleus; Adaptor Proteins, Signal Transducing; Amino Acid Sequence; Carcinogenesis; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Culture Media, Serum-Free; Female; HEK293 Cells; Humans; Male; Middle Aged; Phosphorylation; Phosphothreonine; Protein Binding; Protein Serine-Threonine Kinases; Signal Transduction; Stomach Neoplasms; Stress, Physiological; Transcription Factors; Treatment Outcome; Tumor Suppressor Proteins; YAP-Signaling Proteins

Tumor initiating cells (TIC) of lung cancer are mainly induced by stress-related plasticity. Calcium/Calmodulin dependent protein kinase II alpha (CAMK2A) is a key calcium signaling molecule activated by exogenous and endogenous stimuli with effects on multiple cell functions but little is known about its role on TIC. In human lung adenocarcinomas (AD), CAMK2A was aberrantly activated in a proportion of cases and was an independent risk factor predicting shorter survivals. Functionally, CAMK2A enhanced TIC phenotypes in vitro and in vivo. CAMK2A regulated SOX2 expression by reducing H3K27me3 and EZH2 occupancy at SOX2 regulatory regions, leading to its epigenetic de-repression with functional consequences. Further, CAMK2A caused kinase-dependent phosphorylation of EZH2 at T487 with suppression of EZH2 activity. Together, the data demonstrated the CAMK2A-EZH2-SOX2 axis on TIC regulation. This study provided phenotypic and mechanistic evidence for the TIC supportive role of CAMK2A, implicating a novel predictive and therapeutic target for lung cancer.

Topics: Adenocarcinoma of Lung; Animals; Apoptosis; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Carcinogenesis; Cell Line, Tumor; Cell Self Renewal; Enhancer of Zeste Homolog 2 Protein; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; Mice, SCID; Molecular Targeted Therapy; Neoplastic Stem Cells; Phosphorylation; Phosphothreonine; Regulatory Sequences, Nucleic Acid; SOXB1 Transcription Factors; Survival Analysis; Up-Regulation

Disassembly of nucleosomes in which genomic DNA is packaged with histone regulates gene expression. However, the mechanisms underlying nucleosome disassembly for gene expression remain elusive. We show here that epidermal growth factor receptor activation results in the binding of the RNF8 forkhead-associated domain to pyruvate kinase M2-phosphorylated histone H3-T11, leading to K48-linked polyubiquitylation of histone H3 at K4 and subsequent proteasome-dependent protein degradation. In addition, H3 polyubiquitylation induces histone dissociation from chromatin, nucleosome disassembly, and binding of RNA polymerase II to

Topics: Carcinogenesis; Cell Line, Tumor; Cyclin D1; DNA-Binding Proteins; Epidermal Growth Factor; Gene Expression Regulation; Glycolysis; Histones; Humans; Lysine; Models, Biological; Nucleosomes; Phosphothreonine; Promoter Regions, Genetic; Protein Domains; Proteolysis; Proto-Oncogene Proteins c-myc; Ubiquitin-Protein Ligases; Ubiquitination

Pyruvate kinase M2 isoform (PKM2) catalyzes the last step of glycolysis and plays an important role in tumor cell proliferation. Recent studies have reported that PKM2 also regulates apoptosis. However, the mechanisms underlying such a role of PKM2 remain elusive. Here we show that PKM2 translocates to mitochondria under oxidative stress. In the mitochondria, PKM2 interacts with and phosphorylates Bcl2 at threonine (T) 69. This phosphorylation prevents the binding of Cul3-based E3 ligase to Bcl2 and subsequent degradation of Bcl2. A chaperone protein, HSP90α1, is required for this function of PKM2. HSP90α1's ATPase activity launches a conformational change of PKM2 and facilitates interaction between PKM2 and Bcl2. Replacement of wild-type Bcl2 with phosphorylation-deficient Bcl2 T69A mutant sensitizes glioma cells to oxidative stress-induced apoptosis and impairs brain tumor formation in an orthotopic xenograft model. Notably, a peptide that is composed of the amino acid residues from 389 to 405 of PKM2, through which PKM2 binds to Bcl2, disrupts PKM2-Bcl2 interaction, promotes Bcl2 degradation and impairs brain tumor growth. In addition, levels of Bcl2 T69 phosphorylation, conformation-altered PKM2 and Bcl2 protein correlate with one another in specimens of human glioblastoma patients. Moreover, levels of Bcl2 T69 phosphorylation and conformation-altered PKM2 correlate with both grades and prognosis of glioma malignancy. Our findings uncover a novel mechanism through which mitochondrial PKM2 phosphorylates Bcl2 and inhibits apoptosis directly, highlight the essential role of PKM2 in ROS adaptation of cancer cells, and implicate HSP90-PKM2-Bcl2 axis as a potential target for therapeutic intervention in glioblastoma.

Topics: Amino Acid Sequence; Apoptosis; Carcinogenesis; Cell Line, Tumor; Cullin Proteins; Glioma; HSP90 Heat-Shock Proteins; Humans; Hydrogen Peroxide; Mitochondria; Oxidative Stress; Phosphorylation; Phosphothreonine; Prognosis; Protein Binding; Protein Stability; Protein Transport; Proteolysis; Proto-Oncogene Proteins c-bcl-2; Pyruvate Kinase; Ubiquitin-Protein Ligases

Dietary fructose is primarily metabolized in the liver. Here we demonstrate that, compared with normal hepatocytes, hepatocellular carcinoma (HCC) cells markedly reduce the rate of fructose metabolism and the level of reactive oxygen species, as a result of a c-Myc-dependent and heterogeneous nuclear ribonucleoprotein (hnRNP) H1- and H2-mediated switch from expression of the high-activity fructokinase (KHK)-C to the low-activity KHK-A isoform. Importantly, KHK-A acts as a protein kinase, phosphorylating and activating phosphoribosyl pyrophosphate synthetase 1 (PRPS1) to promote pentose phosphate pathway-dependent de novo nucleic acid synthesis and HCC formation. Furthermore, c-Myc, hnRNPH1/2 and KHK-A expression levels and PRPS1 Thr225 phosphorylation levels correlate with each other in HCC specimens and are associated with poor prognosis for HCC. These findings reveal a pivotal mechanism underlying the distinct fructose metabolism between HCC cells and normal hepatocytes and highlight the instrumental role of KHK-A protein kinase activity in promoting de novo nucleic acid synthesis and HCC development.

Topics: Carcinogenesis; Carcinoma, Hepatocellular; Fructokinases; Heterogeneous-Nuclear Ribonucleoprotein Group F-H; Humans; Liver Neoplasms; Nucleic Acids; Phosphorylation; Phosphothreonine; Proto-Oncogene Proteins c-myc; Reactive Oxygen Species; Ribose-Phosphate Pyrophosphokinase; RNA Splicing

The MYC proto-oncogene is a transcription factor implicated in a broad range of cancers. MYC is regulated by several post-translational modifications including SUMOylation, but the functional impact of this post-translational modification is still unclear. Here, we report that the SUMO E3 ligase PIAS1 SUMOylates MYC. We demonstrate that PIAS1 promotes, in a SUMOylation-dependent manner, MYC phosphorylation at serine 62 and dephosphorylation at threonine 58. These events reduce the MYC turnover, leading to increased transcriptional activity. Furthermore, we find that MYC is SUMOylated in primary B cell lymphomas and that PIAS1 is required for the viability of MYC-dependent B cell lymphoma cells as well as several cancer cell lines of epithelial origin. Finally, Pias1-null mice display endothelial defects reminiscent of Myc-null mice. Taken together, these results indicate that PIAS1 is a positive regulator of MYC.

Topics: Animals; Carcinogenesis; Cell Line; Cell Proliferation; Cell Survival; Gene Expression Regulation, Neoplastic; Half-Life; Humans; Lymphoma, B-Cell; Mice; Phosphorylation; Phosphothreonine; Protein Binding; Protein Inhibitors of Activated STAT; Proteolysis; Proto-Oncogene Mas; Proto-Oncogene Proteins c-myc; Sumoylation; Transcription, Genetic; Up-Regulation

Abnormal expression of cyclin-dependent kinase 5 (CDK5) has been found in several human cancers, whereas the role of CDK5 in the malignant development of colorectal cancer (CRC) has not been well characterized. Here we investigated the role of CDK5 in CRC and found that its expression was much higher in CRC tissues than that in normal tissues with a higher expression level of CDK5 closely correlating to advanced American Joint Committee on Cancer (AJCC) stage, poor differentiation, increased tumor size and poor prognosis of CRC. Biological function experiments showed that CDK5 regulated CRC cell proliferation and metastasis ability. Whole-genome microarray analysis, co-immunoprecipitation, in vitro kinase assay, western blotting, luciferase reporter assays and electrophoretic mobility shift assay (EMSA) showed that CDK5 could directly phosphorylate ERK5 at threonine (Thr) 732 and finally modulate the oncogenic ERK5-AP-1 axis. Further researches showed that CDK5-ERK5-AP-1 axis could promote progression of CRC carcinogenesis and had a significant correlation in human CRC samples. In summary, this study revealed the functional and mechanistic links between CDK5 and the oncogenic ERK5-AP-1 signaling pathway in the pathogenesis of CRC. These findings suggest that CDK5 has an important role in CRC development and may serve as a potential therapeutic target for CRC.

Topics: Adaptor Proteins, Signal Transducing; Carcinogenesis; Cell Cycle Proteins; Cell Line, Tumor; Cell Movement; Cell Proliferation; Colorectal Neoplasms; Cyclin-Dependent Kinase 5; Disease Progression; Down-Regulation; Female; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; Male; Middle Aged; Mitogen-Activated Protein Kinase 7; Neoplasm Invasiveness; Neoplasm Metastasis; Phosphorylation; Phosphothreonine; Signal Transduction; Survival Analysis; Transcription Factor AP-1; Up-Regulation