LHPP suppresses proliferation, migration, and invasion and promotes apoptosis in pancreatic cancer

Oncolytic adenovirus encoding LHPP exerts potent antitumor effect in lung cancer

LHPP has been shown to be a new tumor suppressor, and has a tendency to be under-expressed in a variety of cancers. Oncolytic virotheray is a promising therapeutics for lung cancer in recent decade years. Here we successfully constructed a new recombinant oncolytic adenovirus GD55-LHPP and investigated the effect of GD55-LHPP on the growth of lung cancer cells in vitro and in vivo. The results showed that LHPP had lower expression in either lung cancer cells or clinical lung cancer tissues compared with normal cells or tissues, and GD55-LHPP effectively mediated LHPP expression in lung cancer cells. GD55-LHPP could effectively inhibit the proliferation of lung cancer cell lines and rarely affected normal cell growth. Mechanically, the oncolytic adenovirus GD55-LHPP was able to induce stronger apoptosis of lung cancer cells compared with GD55 through the activation of caspase signal pathway. Notably, GD55-LHPP also activated autophagy-related signal pathway. Further, GD55-LHPP efficiently inhibited tumor growth in lung cancer xenograft in mice and prolonged animal survival rate compared with the control GD55 or PBS. In conclusion, the novel construct GD55-LHPP provides a valuable strategy for lung cancer-targeted therapy and develop the role of tumor suppress gene LHPP in lung cancer gene therapy.

LHPP expression in triple-negative breast cancer promotes tumor growth and metastasis by modulating the tumor microenvironment

Triple-negative breast cancer (TNBC) is a highly aggressive and metastatic form of breast cancer that lacks an effective targeted therapy. To identify new therapeutic targets, we investigated the phosphohistidine phosphatase, LHPP, which has been implicated in the development of several types of cancer. However, the full significance of LHPP in cancer progression remains unclear due to our limited understanding of its molecular mechanism. We found that levels of the LHPP phosphohistidine phosphatase were significantly increased in human breast cancer patients compared to normal adjacent tissues, with the highest levels in the TNBC subtype. When LHPP was knocked out in the MDA-MB-231 human TNBC cell line, cell proliferation, wound healing capacity, and invasion were significantly reduced. However, LHPP knockout in TNBC cells did not affect the phosphohistidine protein levels. Interestingly, LHPP knockout in MDA-MB-231 cells delayed tumor growth and reduced metastasis when orthotopically transplanted into mouse mammary glands. To investigate LHPP's role in breast cancer progression, we used next-generation sequencing and proximity-labeling proteomics, and found that LHPP regulates gene expression in chemokine-mediated signaling and actin cytoskeleton organization. Depletion of LHPP reduced the presence of tumor-infiltrating macrophages in mouse xenografts. Our results uncover a new tumor promoter role for LHPP phosphohistidine phosphatase in TNBC and suggest that targeting LHPP phosphatase could be a potential therapeutic strategy for TNBC.

Construction of an oxidative phosphorylation-related gene signature for predicting prognosis and identifying immune infiltration in osteosarcoma

BACKGROUND

Osteosarcoma is a prevalent malignant tumor that originates from mesenchymal tissue. It typically affects children and adolescents. Although it is known that the growth of osteosarcoma relies on oxidative phosphorylation for energy production, limited attention has been paid to exploring the potential of oxidative phosphorylation-related genes in predicting the prognosis of individuals suffering from osteosarcoma.

METHODS

All the data were retrieved from the UCSC Xena and GEO (GENE EXPRESSION OMNIBUS). Identification of the oxidative phosphorylation genes linked to the prognosis of individuals with osteosarcoma was done by means of univariate COX and LASSO regression analyses. Following that, patients were categorized into a high-risk group and a low-risk group as per the risk score determined by the identified oxidative phosphorylation genes. Furthermore, a comparison was made in terms of the survival and immune infiltration between both groups, and the prognostic model was established.

RESULTS

Five oxidative phosphorylation genes (ATP6V0D1, LHPP, COX6A2, MTHFD2, NDUFB9) associated with the prognosis of individuals with osteosarcoma were identified and the risk prognostic models were constructed. In the current research, the analysis of the ROC curves indicated a superior predictive accuracy exhibited by the risk model. The prognosis was adversely affected by immune infiltration in the high-risk group in comparison with the low-risk group. The function of the oxidative phosphorylation-related prognostic gene set was verified by GO and KEGG analysis. Furthermore, the link between oxidative phosphorylation-related genes and osteosarcoma immune infiltration was examined by GSEA analysis.

CONCLUSIONS

In this study, a prognostic model that demonstrated good predictive performance was constructed. Additionally, this study highlighted a correlation between oxidative phosphorylation-related genes and immune infiltration.

The histidine phosphatase LHPP of Penaeus vannamei is involved in shrimp hemocytes apoptosis

LHPP (Phospholysine Phosphohistidine Inorganic Pyrophosphate Phosphatase) is a protein histidine phosphatase that modulates a hidden posttranslational modification called histidine phosphorylation. LHPP also acts as a tumor suppressor, which plays a pivotal role in various cellular processes. However, whether LHPP participates in the regulation of invertebrate's immunity is still unknown. Here we characterized a LHPP homolog in P. vannamei (designated PvLHPP), with a 807 bp length of open reading frame (ORF) encoding a putative protein of 268 amino acids. Sequence analysis revealed that PvLHPP contains a typical hydrolase 6 and hydrolase-like domain, which was conserved from invertebrate to vertebrate. PvLHPP was ubiquitously expressed in tissues and induced in hemocyte and hepatopancreas by Vibrio parahaemolyticus, Streptococcus iniae and white spot syndrome virus (WSSV) challenge, indicating that PvLHPP participated in the immune responses. Moreover, silencing of PvLHPP followed by V. parahaemolyticus inhibited hemocyte apoptosis. This study enriches our current insight on shrimp immunity, and provides novel perspective to understand immune-regulatory role of PvLHPP.

Aberrant expression of PELI1 caused by Jagged1 accelerates the malignant phenotype of pancreatic cancer

Pancreatic cancer is one of the most aggressive cancers. PELI1 has been reported to promote cell survival and proliferation in multiple cancers. As of now, the role of PELI1 in pancreatic cancer is largely unknown. Here, we found that the PELI1 mRNA was higher expressed in pancreatic tumor tissues than in adjacent normal tissues, and the high PELI1 level in pancreatic cancer patients had a short survival time compared with the low level. Moreover, the results showed that PELI1 promoted cell proliferation, migration, and invasion, and inhibited apoptosis in vitro. Xenograft tumor experiments were used to determine the biological function of PELI1, and the results showed that PELI1 promoted tumor growth in vivo. Additionally, we found that Jagged1 activated PELI1 transcription in pancreatic cancer cells. To sum up, our results show that PELI1 affects the malignant phenotype of pancreatic cancer.

Glomerular proteomic profiling reveals early differences between preexisting and de novo type 2 diabetes in human renal allografts

BACKGROUND

Diabetes mellitus (DM), either preexisting or developing after transplantation, remains a crucial clinical problem in kidney transplantation. To obtain insights into the molecular mechanisms underlying PTDM development and early glomerular damage before the development of histologically visible diabetic kidney disease, we comparatively analysed the proteome of histologically normal glomeruli from patients with PTDM and normoglycaemic (NG) transplant recipients. Moreover, to assess specificities inherent in PTDM, we also comparatively evaluated glomerular proteomes from transplant recipients with preexisting type 2 DM (T2DM).

METHODS

Protocol biopsies were obtained from adult NG, PTDM and T2DM patients one year after kidney transplantation. Biopsies were formalin-fixed and embedded in paraffin, and glomerular cross-sections were microdissected. A total of 4 NG, 7 PTDM and 6 T2DM kidney biopsies were used for the analysis. The proteome was determined by liquid chromatography-tandem mass spectrometry. Relative differences in protein abundance and significantly dysregulated pathways were analysed.

RESULTS

Proteins involved in cell adhesion, immune response, leukocyte transendothelial filtration, and cell localization and organization were less abundant in glomeruli from PTDM patients than in those from NG patients, and proteins associated with supramolecular fibre organization and protein-containing complex binding were more abundant in PTDM patients. Overall, proteins related to adherens and tight junctions and those related to the immune system, including leukocyte transendothelial migration, were more abundant in NG patients than in transplanted patients with DM, irrespective of the timing of its development. However, proteins included in cell‒cell junctions and adhesion, insulin resistance, and vesicle-mediated transport were all less abundant in PTDM patients than in T2DM patients.

CONCLUSIONS

The glomerular proteome profile differentiates PTDM from NG and T2DM, suggesting specific pathogenetic mechanisms. Further studies are warranted to validate these results, potentially leading to an improved understanding of PTDM kidney transplant pathophysiology and to the identification of novel biomarkers.

Phospholysine phosphohistidine inorganic pyrophosphate phosphatase suppresses human esophageal cancer cell growth by inducing mitotic catastrophe through the P27/cyclin A/CDK2 signaling pathway

Esophageal cancer (ESCA) is a global dead malignancy with poor prognosis. However, its underlying molecular mechanism remains to be elucidated. Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) has been reported as a tumor suppressor in multisystem cancer but its function in ESCA has not been reported. We analyzed LHPP expression between normal and tumor tissues of ESCA patients and performed LHPP overexpression on the ESCA cells KYSE-150 (K150). We did not observe significant differences in the expression level of LHPP between ESCA and normal tissue, and noticed that LHPP expression was not related to ESCA patient survival rate. However, increased expression of LHPP in K150 cells induced mitochondrial dysfunction, inhibited cell proliferation, migration, and cell cycle, and simultaneously increased cell apoptosis. Besides, we found that K150 cells underwent mitotic catastrophe after overexpressing LHPP, which may be regulated through the P27/cyclin A/cdk2 signaling pathway. Although the expression of LHPP may not be related to the progression and prognosis of ESCA, mitotic catastrophe, a new mechanism of tumor suppressor function of LHPP was found after overexpressing LHPP in ESCA cells. DATA AVAILABILITY: The data used to support the findings of this study are included within the article.

Colitis Is Associated with Loss of the Histidine Phosphatase LHPP and Upregulation of Histidine Phosphorylation in Intestinal Epithelial Cells

Protein histidine phosphorylation (pHis) is a posttranslational modification involved in cell cycle regulation, ion channel activity and phagocytosis. Using novel monoclonal antibodies to detect pHis, we previously reported that the loss of the histidine phosphatase LHPP (phospholysine phosphohistidine inorganic pyrophosphate phosphatase) results in elevated pHis levels in hepatocellular carcinoma. Here, we show that intestinal inflammation correlates with the loss of LHPP in dextran sulfate sodium (DSS)-treated mice and in inflammatory bowel disease (IBD) patients. Increased histidine phosphorylation was observed in intestinal epithelial cells (IECs), as determined by pHis immunofluorescence staining of colon samples from a colitis mouse model. However, the ablation of Lhpp did not cause increased pHis or promote intestinal inflammation under physiological conditions or after DSS treatment. Our observations suggest that increased histidine phosphorylation plays a role in colitis, but the loss of LHPP is not sufficient to increase pHis or to cause inflammation in the intestine.

LHPP suppresses proliferation, migration, and invasion in hepatocellular carcinoma and pancreatic cancer by inhibiting EGFR signaling pathway

Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) has been reported to be a new tumor suppressor with a significant inhibitory effect in various cancers. Although LHPP has been repeatedly shown to inhibit the progression of various tumors by inhibiting the phosphorylation of AKT, up to now, the studies on the function and mechanism of LHPP in tumors are insufficient. In this study, LHPP expression was found to be downregulated in both hepatocellular carcinoma (HCC) and pancreatic cancer (PC). Here, we found that LHPP could bind to epidermal growth factor receptor (EGFR) and inhibit its phosphorylation, which thereby inhibited the activation of EGFR downstream pathways ERK, AKT, and STAT3, and then weakening the ability to proliferate, invade, and migrate in HCC and PC. This paper showed a new physiological function of LHPP in inhibiting phosphorylation of EGFR and its potential anti-tumor mechanism and indicated that LHPP was a potential therapeutic target for HCC and PC.

Graphene oxide nanoarchitectures in cancer biology: Nano-modulators of autophagy and apoptosis

Nanotechnology is a growing field, with many potential biomedical applications of nanomedicine for the treatment of different diseases, particularly cancer, on the horizon. Graphene oxide (GO) nanoparticles can act as carbon-based nanocarriers with advantages such as a large surface area, good mechanical strength, and the capacity for surface modification. These nanostructures have been extensively used in cancer therapy for drug and gene delivery, photothermal therapy, overcoming chemotherapy resistance, and for imaging procedures. In the current review, we focus on the biological functions of GO nanoparticles as regulators of apoptosis and autophagy, the two major forms of programmed cell death. GO nanoparticles can either induce or inhibit autophagy in cancer cells, depending on the conditions. By stimulating autophagy, GO nanocarriers can promote the sensitivity of cancer cells to chemotherapy. However, by impairing autophagy flux, GO nanoparticles can reduce cell survival and enhance inflammation. Similarly, GO nanomaterials can increase ROS production and induce DNA damage, thereby sensitizing cancer cells to apoptosis. In vitro and in vivo experiments have investigated whether GO nanomaterials show any toxicity in major body organs, such as the brain, liver, spleen, and heart. Molecular pathways, such as ATG, MAPK, JNK, and Akt, can be regulated by GO nanomaterials, leading to effects on autophagy and apoptosis. These topics are discussed in this review to shed some lights towards the biomedical potential of GO nanoparticles and their biocompatibility, paving the way for their future application in clinical trials.

Does the LHPP gene share a common biological function in pancancer progression?

Although emerging evidence has revealed that LHPP, a histidine phosphatase protein, suppresses the progression of different cancers, a pan-cancer analysis still remains unavailable. Therefore, we first utilized different bioinformatics tools to explore the tumor inhibitory role of LHPP protein across 33 tumor types based on the TCGA project. Additionally, HGC-27 gastric cancer cells were used to evaluate the biological functions of LHPP after stable transfection with lentiviruses. Consequently, LHPP mRNA and protein expression were down-regulated in the most cancer tissues corresponding to normal tissues. The data showed that patients with higher LHPP performance had a better prognosis of overall survival (OS) and disease-free survival (DFS) in brain glioma and renal carcinoma. In addition, we found that enhancement of LHPP expression attenuated the proliferation, migration and invasion of gastric cancer cells. The expression levels of cell-cycle-related and EMT-related molecules, such as CDK4, CyclinD1, Vimentin and Snail, were clearly reduced. Moreover, a genetic alteration analysis showed that the most frequent mutation types in LHPP protein was amplification. The patients without LHPP mutation showed a better tendency of prognosis in UCEC, STAD and COAD. Cancer-associated fibroblast infiltration was also observed in head and neck squamous cell carcinoma, stomach adenocarcinoma and testicular germ cell tumors. In summary, our pancancer analysis among various tumor types could provide a comprehensive understanding of LHPP biological function in the progression of malignant diseases and promote the development of novel therapeutic targets.

Long noncoding RNA DLGAP1-AS2 promotes tumorigenesis and metastasis by regulating the Trim21/ELOA/LHPP axis in colorectal cancer

Background

Long noncoding RNAs (lncRNAs) have driven research focused on their effects as oncogenes or tumor suppressors involved in carcinogenesis. However, the functions and mechanisms of most lncRNAs in colorectal cancer (CRC) remain unclear.

Methods

The expression of DLGAP1-AS2 was assessed by quantitative RT-PCR in multiple CRC cohorts. The impacts of DLGAP1-AS2 on CRC growth and metastasis were evaluated by a series of in vitro and in vivo assays. Furthermore, the underlying mechanism of DLGAP1-AS2 in CRC was revealed by RNA pull down, RNA immunoprecipitation, RNA sequencing, luciferase assays, chromatin immunoprecipitation, and rescue experiments.

Results

We discovered that DLGAP1-AS2 promoted CRC tumorigenesis and metastasis by physically interacting with Elongin A (ELOA) and inhibiting its protein stability by promoting tripartite motif containing 21 (Trim21)-mediated ubiquitination modification and degradation of ELOA. In particular, we revealed that DLGAP1-AS2 decreases phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) expression by inhibiting ELOA-mediated transcriptional activating of LHPP and thus blocking LHPP-dependent suppression of the AKT signaling pathway. In addition, we also demonstrated that DLGAP1-AS2 was bound and stabilized by cleavage and polyadenylation specificity factor (CPSF2) and cleavage stimulation factor (CSTF3).

Conclusions

The discovery of DLGAP1-AS2, a promising prognostic biomarker, reveals a new dimension into the molecular pathogenesis of CRC and provides a prospective treatment target for this disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01675-w.

Identification of Tumor Suppressor Gene LHPP-Based 5-microRNA Signature That Predicts the Early- and Midstage Esophageal Squamous Cell Carcinoma: A Two-Stage Case-Control Study in the Chinese Han Population

Objective

To establish a novel approach for diagnosing early- and midstage esophageal squamous cell carcinoma (ESCC).

Methods

The tumor suppressor gene phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP)–based miRNA signature was identified using next-generation sequencing and 3 biological online prediction systems. This retrospective study established and validated an ESCC prediction model using a test cohort and a validation cohort.

Results

Immunohistochemical staining and real-time quantitative polymerase chain reaction (RT-qPCR) results showed that LHPP protein levels were significantly lower in tissues with early- and midstage ESCC than in adjacent tissues (P < .01). Further, we confirmed that miR-15b-5p, miR-424-5p, miR-497-5p, miR-363-5p, and miR-195-5p inhibited LHPP. These 5 miRNAs were significantly elevated in the plasma of early- and midstage ESCC (P < .05). An ESCC prediction model combining these 5 miRNAs was established. Finally, in the external validation cohort, the model exhibited high discriminative value (sensitivity/specificity: 84.4%/93.3%).

Conclusions

The prediction model has potential implications for diagnosis of early- and midstage ESCC.

Tumor suppressor LHPP suppresses cell proliferation and epithelial-mesenchymal transition in hepatocellular carcinoma cell lines

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer in the world with high mortality due to its high potential of metastasis. Epithelial-mesenchymal transition (EMT) plays a key role in the pathogenesis of HCC occurrence and metastasis. Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) is a novel tumor suppressor. There is little study about LHPP in human HCC development. In the present study, we aimed to investigate the role of LHPP in human HCC cell metastasis. We analyzed the LHPP expression level in human HCC tissues compared with normal tissues in the public database. We detected the mRNA level and protein level of LHPP in transformed liver cell line (LO2) and human HCC cell lines (MHCC-97 H, MHCC-97L, and HepG2). We performed genetic gain and loss of function experiments with LHPP using small interfering RNA (siRNA) and lentivirus infection. Then, we detected that LHPP suppressed proliferation and promoted apoptosis in hepatocellular carcinoma cell lines. Also, we investigated the role of LHPP in the EMT process. Finally, we examined the effect of LHPP on TGF-β-induced EMT. Interestingly, we also found that LHPP expression is positively regulated tumor suppressor p53. Our data showed that LHPP is significantly decreased in the human HCC tissues and human HCC cell lines compared with normal liver tissues and transformed liver cells. Knockdown of LHPP promotes HCC cell proliferation and metastasis, and LHPP expression levels negatively correlate with EMT-related genes. Furthermore, LHPP inhibits TGF-β-induced EMT in HCC cell lines. These studies validate LHPP as a tumor suppressor in liver cancer and provide a new genetic target for HCC diagnosis and treatment.

The histidine phosphatase LHPP: an emerging player in cancer

Cancers continue to have high incidence and mortality rates worldwide. Therefore, cancer control remains the main public health goal. Growing research evidence suggests that phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) plays an important role in inhibiting tumor cell progression. It has been reported in the literature that LHPP is expressed at low levels in tumor tissues and cells and that patients with low LHPP expression have a poorer prognosis. Functional studies have shown that LHPP can inhibit tumor cell proliferation, metastasis, and apoptosis by affecting different target genes. In addition, researchers have used iDPP nanoparticles to deliver LHPP plasmids to treat tumors, demonstrating the great potential of LHPP plasmids for cancer therapy. In our review, we highlight the biological functions and important downstream target genes of LHPP in tumors, providing a theoretical basis for the treatment of human cancers. Although not thoroughly studied in terms of tumor mechanisms, LHPP still represents a promising and effective anticancer drug target.

As a Novel Tumor Suppressor, LHPP Promotes Apoptosis by Inhibiting the PI3K/AKT Signaling Pathway in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) refers to the malignant tumor of the head and neck with a highest morbidity. It exhibits a poor prognosis and unsatisfactory treatment partially attributed to delayed diagnosis. As indicated from existing reports, the protein histidine phosphatase LHPP acts as a vital factor in tumorigenesis in liver, lung, bladder, breast and pancreatic tumor tissues. Thus far, the functional mechanism of LHPP in OSCC remains unclear. DGE analysis, OSCC cell lines and OSCC cases were found that LHPP was down-regulated in OSCC tissues and cells compared with that in normal oral mucosa tissues and cells, and was closely related to OSCC differentiation. Cell counting Kit 8 test, EdU proliferation test, scratches test, invasion test, monoclonal formation test, mouse xenograft tumor model, HE staining and immunohistochemistry showed that LHPP inhibited OSCC growth, proliferation and migration in vivo and in vitro. GO and KEGG enrichment analysis, LHPP transcription factor analysis and flow cytometry found that LHPP promotes the apoptosis of OSCC by decreasing the transcriptional activity of p-PI3K and p-Akt. Finally, our results suggested that LHPP inhibited the progression of OSCC through the PI3K/AKT signaling pathway, indicating that LHPP may be a new target for the treatment of OSCC.

Three LHPP gene-targeting co-expressed microRNAs (microRNA-765, microRNA-21, and microRNA-144) promote proliferation, epithelial-mesenchymal transition, invasion, and are independent prognostic biomarkers in renal cell carcinomas patients

Background

Renal cell carcinoma (RCC) is one of the highly malignant tumors in the world. Global Cancer Statistics 2020 estimated that there were 179,368 deaths from kidney tumors. Therefore, exploring the prognostic biomarkers of RCC is of great significance for RCC patients. This study aims to explore the potential mechanism and prognostic value of phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) gene‐targeting co‐expression microRNAs in RCC patients.

Methods

A total of 60 RCC patients were included. Quantitative real‐time PCR (qRT‐PCR), western blotting, and immunohistochemistry were used for LHPP, microRNA‐765, microRNA‐21, and microRNA‐144 levels evaluation. Cell Counting Kit‐8 assay, dual‐luciferase reporter gene assay, invasion assay, and RNA fluorescence in situ hybridization were used for functional analyses.

Results

Compared with adjacent tissues, LHPP levels in cancer tissues were significantly increased (p < .001). Herein, we confirmed that microRNA‐765, microRNA‐21, and microRNA‐144 were direct biological targets of LHPP. MicroRNA‐765 (r = −0.570, p < 0.001), microRNA‐21 (r = −0.495, p < .001), and microRNA‐144 (r = −0.463, p < .001) expression levels were negatively correlated with LHPP expression levels. The high expression levels of microRNA‐765, microRNA‐21, and microRNA‐144 in RCC tissues were associated with poor differentiation, recurrence, and poor prognosis (p < .05). In vitro, microRNA‐765, microRNA‐21, and microRNA‐144 act as oncogenes to promote proliferation, invasion, and epithelial‐mesenchymal transition (EMT) through targeting LHPP.

Conclusions

MicroRNA‐765, microRNA‐21, and microRNA‐144 are independent risk biomarkers for RCC patients. Inhibiting the expression levels of microRNA‐765, microRNA‐21, and microRNA‐144 can reduce the proliferation, EMT, and invasion of RCC cells. Therefore, the above three microRNAs are expected to become molecular biomarkers for RCC therapy.

The many ways that nature has exploited the unusual structural and chemical properties of phosphohistidine for use in proteins

Histidine phosphorylation is an important and ubiquitous post-translational modification. Histidine undergoes phosphorylation on either of the nitrogens in its imidazole side chain, giving rise to 1- and 3- phosphohistidine (pHis) isomers, each having a phosphoramidate linkage that is labile at high temperatures and low pH, in contrast with stable phosphomonoester protein modifications. While all organisms routinely use pHis as an enzyme intermediate, prokaryotes, lower eukaryotes and plants also use it for signal transduction. However, research to uncover additional roles for pHis in higher eukaryotes is still at a nascent stage. Since the discovery of pHis in 1962, progress in this field has been relatively slow, in part due to a lack of the tools and techniques necessary to study this labile modification. However, in the past ten years the development of phosphoproteomic techniques to detect phosphohistidine (pHis), and methods to synthesize stable pHis analogues, which enabled the development of anti-phosphohistidine (pHis) antibodies, have accelerated our understanding. Recent studies that employed anti-pHis antibodies and other advanced techniques have contributed to a rapid expansion in our knowledge of histidine phosphorylation. In this review, we examine the varied roles of pHis-containing proteins from a chemical and structural perspective, and present an overview of recent developments in pHis proteomics and antibody development.

LHPP suppresses colorectal cancer cell migration and invasion in vitro and in vivo by inhibiting Smad3 phosphorylation in the TGF-β pathway

The roles of phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) in tumorigenesis have been recently proven in hepatocellular carcinoma (HCC), cervical, pancreatic, bladder, and thyroid cancers. Previous research demonstrated that LHPP repressed cell proliferation and growth by inactivating the phosphatidylinositol 3-kinase/AKT signaling pathway in vitro and in vivo. However, the functions and potential mechanisms of LHPP as a tumor suppressor in colorectal cancer (CRC) metastasis are still unknown. Consequently, the Transwell assay and xenograft nude model showed that LHPP inhibited migration and invasion of CRC cells in vitro and in vivo, respectively. The expression of total and nuclear epithelial-to-mesenchymal transition (EMT)-related proteins were significantly reduced after LHPP upregulation. Human Gene Expression Array and IPA (Ingenuity Pathway Analysis) commercial software were applied to identify differentially expressed genes (DEGs) and potential cell signaling pathways. A total of 330 different genes were observed, including 177 upregulated genes and 153 downregulated genes. Bioinformatics analysis suggested that the transforming growth factor-β (TGF-β) signaling pathway was highly inactivated in this study. Then, Smad3 phosphorylation was apparently decreased, whereas Smad7 expression was markedly enhanced after upregulating LHPP expression. These results were proven once again after TGF-β1 stimulation. Furthermore, a specific inhibitor of Smad3 phosphorylation (SIS3) was applied to verify that LHPP repressed EMT of cancer cells by attenuating TGF-β/Smad signaling. The results suggested that suppression of the TGF-β/Smad signaling pathway by LHPP overexpression could be abolished by SIS3.

Prognostic Correlation of Glycolysis-Related Gene Signature in Patients with Laryngeal Cancer

BACKGROUND

Aerobic glycolysis is one of the metabolic characteristics of tumor cells, which is regulated by many genes. The aim of our study was to construct glycolysis-related gene signature to accurately predict the prognosis of laryngeal cancer (LC) patients.

METHODS

We analyzed the mRNA expression profiles of LC patients from The Cancer Genome Atlas (TCGA). Eleven glycolysis-related gene sets were analyzed by gene set enrichment analysis (GSEA). In order to acquire the gene signature related to prognosis, we used univariate and multivariate Cox regression analysis.

RESULTS

We confirmed that a gene signature composed of two genes (STC2, LHPP) can predict the overall survival (OS) of patients with LC. Based on each patient's risk score, we found that the survival results of patients in the high-risk group were significantly lower than those in the low-risk group (log-rank test P-value=0.002). Multivariate Cox regression analysis confirmed that gene signature could independently predict OS in LC patients (HR = 1.981, 95% CI 1.446-2.714 P<0.001). In addition, a nomogram including the age, sex, grade and risk score was constructed. The nomogram demonstrated good accuracy for OS prediction, with a C-index of 0.752.

CONCLUSION

The glycolysis-related two-gene risk score model could be used as a biomarker for LC prognosis.

LHPP exerts a tumor-inhibiting role in glioblastoma via the downregulation of Akt and Wnt/β-catenin signaling

Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) has been recently identified as a novel inhibitor of multiple tumors; however, its role in glioblastoma (GBM) has not been investigated. This study aimed to evaluate whether LHPP exerts a potential tumor-inhibiting role in GBM. Compared with that in normal tissues, LHPP expression was lower in GBM tissues and various GBM cell lines. LHPP up-regulation in GBM cells markedly reduced their proliferation and invasion, and its knockdown had an oncogenic effect on these cells. Further studies revealed that overexpressed LHPP decreased the levels of Akt and glycogen synthase-3β phosphorylation and down-regulated Wnt/β-catenin signaling. By contrast, LHPP knockdown produced opposite effects. Akt suppression markedly abrogated the activation of Wnt/β-catenin signaling induced by LHPP knockdown. The reactivation of Wnt/β-catenin signaling partially reversed the inhibition of tumor growth in GBM mediated by LHPP overexpression. In addition, LHPP overexpression markedly retarded the tumorigenesis of GBM cells in vivo. These findings revealed that LHPP acts a potential inhibitor of tumor growth in GBM, and its overexpression represses GBM proliferation and invasion by down-regulating Akt and Wnt/β-catenin signaling. This work highlights the crucial role of LHPP in GBM progression and suggests its potential as an anticancer target for the treatment of this disease.

NME/NM23/NDPK and Histidine Phosphorylation

The NME (Non-metastatic) family members, also known as NDPKs (nucleoside diphosphate kinases), were originally identified and studied for their nucleoside diphosphate kinase activities. This family of kinases is extremely well conserved through evolution, being found in prokaryotes and eukaryotes, but also diverges enough to create a range of complexity, with homologous members having distinct functions in cells. In addition to nucleoside diphosphate kinase activity, some family members are reported to possess protein-histidine kinase activity, which, because of the lability of phosphohistidine, has been difficult to study due to the experimental challenges and lack of molecular tools. However, over the past few years, new methods to investigate this unstable modification and histidine kinase activity have been reported and scientific interest in this area is growing rapidly. This review presents a global overview of our current knowledge of the NME family and histidine phosphorylation, highlighting the underappreciated protein-histidine kinase activity of NME family members, specifically in human cells. In parallel, information about the structural and functional aspects of the NME family, and the knowns and unknowns of histidine kinase involvement in cell signaling are summarized.

LHPP Inhibits the Proliferation and Metastasis of Renal Cell Carcinoma

Renal cell carcinoma (RCC) is one of the ten most common cancers in the globe. Despite the diagnosis and treatment of renal cell carcinoma that have made great improvements, the morbidity and mortality rates of renal cell carcinoma remain unchanged remarkably. LHPP is a kind of histidine phosphatases, acting as a tumor suppressor in the progression of various cancers. In this study, we found that LHPP was significantly downregulated in RCC tissues and cell lines. Decreased expression of LHPP was closely correlated with tumor size and postoperative metastasis of RCC patients. In addition, overexpression of LHPP inhibited the proliferation and metastasis of RCC. However, suppression of LHPP promoted the proliferation and metastasis of RCC. In conclusion, our results presented the important role of LHPP in the development and progression of RCC.