Systematic pan-cancer analyses of the potential function of the Golgi scaffold protein PAQR3

Progesterone and AdipoQ Receptor 3 (PAQR3) is a member of the AdipoQ receptor. Our previous studies have found that PAQR3 plays a role as a candidate inhibitor in cardiac adenocarcinoma, breast cancer, gastric cancer and colorectal cancer, but the systematic analysis of PAQR3 in tumors is currently lacking. The objective of this study was to investigate the prognostic and therapeutic value of PAQR3 in 31 tumors. Through the analysis of TCGA, UALCAN, GEO, GEPIA2, TIMER, Kaplan-Meier plotter, TISIDB and other databases, it was found that the expression level of PAQR3 changed significantly in different tumor types, and the expression level of Neuroblastoma was very high. And the level of Prostate adenocarcinoma is low. In addition, the expression level of PAQR3 in Cholangiocarcinoma, Esophageal carcinoma, Head and neck squamous carcinoma, Liver Hepatocellular Carcinoma, Lung Adenocarcinoma and Lung squamous cell carcinoma was significantly higher than that in normal tissues. However, the expression level of PAQR3 in Breast Cancer, Kidney Renal Clear Cell Carcinoma, Kidney renal papillary cell carcinoma, Prostate Adenocarcinoma, Rectum Adenocarcinoma, Thyroid Cancer and Uterine Corpus Endometrial Carcinoma was lower than that in normal tissues. Subsequently, we explored the value of PAQR3 as a prognostic indicator of cancer. In Acute Myeloid Leukemia, Lower-grade Glioma and Glioblastoma, Pediatric Low-grade Gliomas, Kidney Chromophobe, and Thyroid Cancer, PAQR3 expression was positively correlated with OS and DSS, while in Rectum Adenocarcinoma, PAQR3 expression was negatively correlated with OS. PAQR3 high expression group Lower-grade Glioma and Glioblastoma, Pediatric Low-grade Gliomas, Uveal Melanoma, Kidney Chromophobe and DFI were positively correlated. PAQR3 can be used as a risk factor for the prognosis of multiple tumors. Then, we discussed the correlation between PAQR3 and immunology, and found that PAQR3 has a wide range of mutations in various tumor types, the most common mutation type is missense mutation, and common mutation types also include amplification, depth deletion, splicing, truncation and structural variation. Among the tumor samples with PAQR3 alterations, mutation occurred in all tumor samples except prostate adenocarcinoma and adrenal cortical carcinoma, head and neck squamous cell carcinoma, brain low-grade glioma, and kidney clear cell carcinoma, while esophageal adenocarcinoma had the highest total alteration frequency. PAQR3 was strongly associated with CNV in 18 tumors, particularly in Ovarian cancer, Lung squamous cell carcinoma, and Adenoid cystic carcinoma. On the other hand, PAQR3 has a higher SNV frequency in Uterine Corpus Endometrial Carcinoma, Skin Cutaneous Melanoma and Lung Adenocarcinoma, among which Uterine Corpus Endometrial Carcinoma has the highest SNV frequency. These results showed that PAQR3 expression levels were significantly correlated with tumor mutation load, microsatellite instability, neoantigens, and purity. In summary, PAQR3 can affect the tumor microenvironment and has potential for chemotherapy. Finally, we investigated the role of PAQR3 in tumor resistance and found that the expression of PAQR3 affects the efficacy of multiple chemotherapy drugs. Based on these studies, we found that PAQR3 plays an important role in cancer and has potential in tumor diagnosis and prognosis.

Methyltransferase-like proteins in cancer biology and potential therapeutic targeting

RNA modification has recently become a significant process of gene regulation, and the methyltransferase-like (METTL) family of proteins plays a critical role in RNA modification, methylating various types of RNAs, including mRNA, tRNA, microRNA, rRNA, and mitochondrial RNAs. METTL proteins consist of a unique seven-beta-strand domain, which binds to the methyl donor SAM to catalyze methyl transfer. The most typical family member METTL3/METTL14 forms a methyltransferase complex involved in N6-methyladenosine (m6A) modification of RNA, regulating tumor proliferation, metastasis and invasion, immunotherapy resistance, and metabolic reprogramming of tumor cells. METTL1, METTL4, METTL5, and METTL16 have also been recently identified to have some regulatory ability in tumorigenesis, and the rest of the METTL family members rely on their methyltransferase activity for methylation of different nucleotides, proteins, and small molecules, which regulate translation and affect processes such as cell differentiation and development. Herein, we summarize the literature on METTLs in the last three years to elucidate their roles in human cancers and provide a theoretical basis for their future use as potential therapeutic targets.

Oncofetal protein IGF2BPs in human cancer: functions, mechanisms and therapeutic potential

N⁶-methyladenosine (m⁶A) is the most prevalent and well-characterized internal chemical modification in eukaryotic RNA, influencing gene expression and phenotypic changes by controlling RNA fate. Insulin-like growth factor-2 mRNA-binding proteins (IGF2BPs) preferentially function as m⁶A effector proteins, promoting stability and translation of m⁶A-modified RNAs. IGF2BPs, particularly IGF2BP1 and IGF2BP3, are widely recognized as oncofetal proteins predominantly expressed in cancer rather than normal tissues, playing a critical role in tumor initiation and progression. Consequently, IGF2BPs hold potential for clinical applications and serve as a good choice for targeted treatment strategies. In this review, we discuss the functions and mechanisms of IGF2BPs as m⁶A readers and explore the therapeutic potential of targeting IGF2BPs in human cancer.

The role of KMT2 gene in human tumors

Histone methylation plays a crucial role in the regulation of gene transcriptional expression, and aberration of methylation-modifying enzyme genes can lead to a variety of genetic diseases, including human cancers. The histone modified protein KMT2 (lysin methyltransferase) family are involved in cell proliferation, growth, development and differentiation through regulating gene expression, and are closely related with many blood cancers and solid tumors. In recent years, several studies have shown that mutations in the KMT2 gene occur frequently in a variety of human cancers and the mutation status of the KMT2 gene may be correlated with the occurrence, development and prognosis of some tumors. Research uncovering the clinical characteristics and molecular mechanisms of KMT2 mutation in human tumors will be helpful for early diagnosis and prognosis of tumors as well as drug development for targeted therapies.

DEC1 promotes progression of Helicobacter pylori-positive gastric cancer by regulating Akt/NF-κB pathway

Helicobacter pylori (H. pylori) infection plays a crucial role in the initiation and progression of gastric cancer (GC). Differentiated embryo‐chondrocyte expressed gene 1 (DEC1) is dysregulated in some cancers and may regulate cell proliferation in specific contexts. Of note, DEC1 is emerging as one of the important factors regulating cellular responses in microenvironment. However, the triggers and precise regulation mechanism for DEC1 during inflammatory carcinoma transformation of GC are unclear. In this study, we identified DEC1 was upregulated in both H. pylori‐infected gastric tissues and GC cells. DEC1 expression was positively associated with H. pylori infection status and GC progression. DEC1‐positive expression indicated a poorer prognosis in H. pylori‐positive GC. DEC1 was required for H. pylori‐induced GC cells proliferation. Mechanistically, H. pylori infection significantly activated Akt/NF‐κB signal pathway and this induction depend on DEC1 expression level in GC cells. Importantly, their interaction pathway was further verified by H. pylori‐positive gastritis mice model. Taken together, our findings identified a novel function of DEC1 in GC. H. pylori infection induce DEC1 expression, and which leading to the progression of GC through activating Akt/ NF‐κB signalling pathway. Blocking DEC1/Akt/NF‐κB, therefore, presents a promising novel therapeutic strategy for H. pylori‐positive GC.

Circulating methylated THBS1 DNAs as a novel marker for predicting peritoneal dissemination in gastric cancer

Objectives

Thrombospondin 1 (THBS1) is known to play a key role in tumor metastasis, and aberrant DNA methylation is one of the mechanisms regulating THBS1. The present study investigated whether methylated THBS1 in circulating cell‐free DNA from preoperative peritoneal lavage fluid (PPLF) and peripheral blood could be used as a potential biomarker for predicting peritoneal dissemination in gastric cancer (GC) patients.

Methods

The status of THBS1 methylation was detected by quantitative methylation‐specific PCR (MSP) in tumor tissues, paired PPLF, and serum from 92 GC patients. The correlation between methylated THBS1 levels and peritoneal dissemination of GC was studied, and its diagnostic value for predicting peritoneal dissemination was clarified by the receiver operating characteristic (ROC) curve.

Results

Aberrant THBS1 methylation in tumor tissues was significantly higher than that in paracancerous normal tissues (p < 0.0001). No THBS1 methylation was found in 40 healthy controls, and partial methylation was detected in 3 of 48 patients with chronic non‐atrophic gastritis. The frequency of THBS1 methylation in pairing PPLF and serum from 92 GC patients was 52.2% (48/92) and 58.7% (54/92), respectively. The results of methylated THBS1 in pairing PPLF and serum were similar to those of tumor tissues. Aberrant THBS1 methylation in tumor tissues and pairing PPLF or serum was closely related to peritoneal dissemination, tumor progression, and poor prognosis (all p < 0.0001).

Conclusion

Circulating methylated THBS1 DNAs in PPLF/serum may predict peritoneal dissemination, a potential poor prognostic factor for GC patients.

A Potential Oncogenic Role for PFKFB3 Overexpression in Gastric Cancer Progression

OBJECTIVES

PFKFB3 regulates glycolysis in tumor cells, might function as an oncogene, and is associated with cancer metastasis. However, its role in gastric cancer (GC) remains largely unknown.

METHODS

PFKFB3 expression was assessed by immunohistochemistry (IHC) in GC tissues and paired paracancerous histological normal tissues (PCHNTs). The associations of PFKFB3 expression with clinical features and HIF-1α, Ki-67, E-cadherin, Snail, and Vimentin expression levels were assessed. A series of in vivo and in vitro experiments were performed to investigate the effects of PFKFB3 on the growth, migration, and invasion of GC cells.

RESULTS

We found that PFKFB3 expression was significantly higher in GC tissues compared with PCHNTs (P = 0.000). PFKFB3 expression was positively correlated with tumor size (P = 0.000), differentiation (P = 0.025), venous invasion (P = 0.084), nerve invasion (P = 0.014), lymphatic invasion (P = 0.000), local invasion (P = 0.000), invasive depth (P = 0.000), nodal metastasis (P = 0.000), tumor-node-metastasis stage (P = 0.000), and patient survival (P = 0.000). Notably, PFKFB3 upregulation was highly correlated with increased epithelial-mesenchymal transition (EMT) in GC samples. PFKFB3 overexpression positively modulated cell proliferation, migration, and EMT in GC cells in vitro, with concomitant activation of NF-κB signaling. Administration of an NF-κB inhibitor attenuated PFKFB3-induced EMT in GC cells. PFKFB3 overexpression promoted tumor development and EMT in nude mice, which were attenuated by PFK-15, a PFKFB3 inhibitor.

DISCUSSION

PFKFB3 could potentiate malignancy in GC cells through NF-κB pathway-mediated EMT, suggesting PFKFB3 represents a potential target for GC therapy.

Acetylation Stabilizes Phosphoglycerate Dehydrogenase by Disrupting the Interaction of E3 Ligase RNF5 to Promote Breast Tumorigenesis

Phosphoglycerate dehydrogenase (PHGDH) is the first enzyme in the serine synthesis pathway in which it is also the rate-limiting enzyme. It is significantly upregulated in many cancers, especially breast cancer. However, the posttranslational mechanism of PHGDH upregulation in breast cancer is unknown. In this study, we find that RNF5, an E3 ubiquitin ligase, is essential for the degradation of PHGDH protein. PHGDH is degraded by RNF5 to prevent the proliferation of breast cancer cells. The acetylation of PHGDH at K58 is able to disrupt the interaction of RNF5-PHGDH and promote the proliferation of breast cancer cells. Tip60 and SIRT2 regulate the reversible acetylation modification of PHGDH in response to glucose alteration. Moreover, PHGDH is significantly upregulated in samples of human breast cancer and is associated with decreased RNF5 expression. This implies a potential therapeutic target through the interference interaction of PHGDH-RNF5 to degrade PHGDH in breast cancer.

Oxidative stress-mediated AMPK inactivation determines the high susceptibility of LKB1-mutant NSCLC cells to glucose starvation

The liver kinase B1 (LKB1) is an important tumor suppressor and its loss-of-function mutations are observed in around 16% of non-small cell lung cancer (NSCLC) cases. One of the main functions of LKB1 is to activate AMP-activated protein kinase (AMPK) via direct phosphorylation. Under metabolic or energy stress conditions, the LKB1-AMPK axis inhibits the anabolic pathways and activates the catabolic pathways to maintain metabolic homeostasis for cell survival. In this study, we found that LKB1-mutant NSCLC cells are particularly susceptible to cell death induced by glucose starvation, but not by other forms of starvation such as amino acid starvation or serum starvation. Reconstitution of LKB1 in LKB1-mutant cells or LKB1 knockout in LKB1-wild type cells highlighted the importance of the LKB1-AMPK axis for cell survival under glucose starvation. Mechanistically, in LKB1-mutant cells, glucose starvation elicits oxidative stress, which causes AMPK protein oxidation and inactivation, and eventually cell death. Importantly, this process could be effectively reversed and rescued by 2DG (a glucose analog capable of producing NADPH, a key antioxidant), A769662 (an allosteric AMPK activator), and N-acetyl cysteine (NAC) (a ROS scavenger), indicating the presence of a vicious circle between AMPK inactivation and ROS in LKB1-mutant NSCLC cells under glucose starvation. Our study thus elucidates the critical role of redox balance in determining the susceptibility to cell death under glucose starvation in LKB1-mutant NSCLC cells. The findings from this study reveal important clues in search of novel therapeutic strategies for LKB1-mutant NSCLC by targeting glucose metabolism and redox balance.

Autocrine INSL5 promotes tumor progression and glycolysis via activation of STAT5 signaling

Metabolic reprogramming plays important roles in development and progression of nasopharyngeal carcinoma (NPC), but the underlying mechanism has not been completely defined. In this work, we found INSL5 was elevated in NPC tumor tissue and the plasma of NPC patients. Plasma INSL5 could serve as a novel diagnostic marker for NPC, especially for serum VCA-IgA-negative patients. Moreover, higher plasma INSL5 level was associated with poor disease outcome. Functionally, INSL5 overexpression increased, whereas knockdown of its receptor GPCR142 or inhibition of INSL5 reduced cell proliferation, colony formation, and cell invasion in vitro and tumorigenicity in vivo. Mechanistically, INSL5 enhanced phosphorylation and nuclear translocation of STAT5 and promoted glycolytic gene expression, leading to induced glycolysis in cancer cells. Pharmaceutical inhibition of glycolysis by 2-DG or blockade of INSL5 by a neutralizing antibody reversed INSL5-induced proliferation and invasion, indicating that INSL5 can be a potential therapeutic target in NPC. In conclusion, INSL5 enhances NPC progression by regulating cancer cell metabolic reprogramming and is a potential diagnostic and prognostic marker as well as a therapeutic target for NPC.

Polyamine synthesis enzyme AMD1 is closely associated with tumorigenesis and prognosis of human gastric cancers

Adenosylmethionine decarboxylase 1 (AMD1) is a key enzyme involved in biosynthesis of polyamines including spermidine and spermine. The potential function of AMD1 in human gastric cancers is unknown. We analyzed AMD1 expression level in 319 human gastric cancer samples together with the adjacent normal tissues. The protein expression level of AMD1 was significantly increased in human gastric cancer samples compared with their corresponding para-cancerous histological normal tissues (P < 0.0001). The expression level of AMD1 was positively associated with Helicobactor pylori 16sRNA (P < 0.0001), tumor size (P < 0.0001), tumor differentiation (P < 0.05), tumor venous invasion (P < 0.0001), tumor lymphatic invasion (P < 0.0001), blood vessel invasion (P < 0.0001), and tumor lymph node metastasis (TNM) stage (P < 0.0001). Patients with high expression of AMD1 had a much shorter overall survival than those with normal/low expression of AMD1. Knockdown of AMD1 in human gastric cancer cells suppressed cell proliferation, colony formation and cell migration. In a tumor xenograft model, knockdown of AMD1 suppressed the tumor growth in vivo. Inhibition of AMD1 by an inhibitor SAM486A in human gastric cancer cells arrested cell cycle progression during G1-to-S transition. Collectively, our studies at the cellular, animal and human levels indicate that AMD1 has a tumorigenic effect on human gastric cancers and affect the prognosis of the patients.

Characterization of the Golgi scaffold protein PAQR3, and its role in tumor suppression and metabolic pathway compartmentalization

The Golgi apparatus is critical in the compartmentalization of signaling cascades originating from the cytoplasmic membrane and various organelles. Scaffold proteins, such as progestin and adipoQ receptor (PAQR)3, specifically regulate this process, and have recently been identified in the Golgi apparatus. PAQR3 belongs to the PAQR family, and was recently described as a tumor suppressor. Accumulating evidence demonstrates PAQR3 is downregulated in different cancers to suppress its inhibitory effects on malignant potential. PAQR3 functions biologically through the pathological regulation of altered signaling pathways. Significant cell proliferation networks, including Ras proto-oncogene (Ras)/mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt), insulin, and vascular endothelial growth factor, are closely controlled by PAQR3 for physiologically relevant effects. Meanwhile, genetic/epigenetic susceptibility and environmental factors, may have functions in the downregulation of PAQR3 in human cancers. This study aimed to assess the subcellular localization of PAQR3 and determine its topological features and functional domains, summarizing its effects on cell signaling compartmentalization. The pathophysiological functions of PAQR3 in cancer pathogenesis, metabolic diseases, and developmental ailments were also highlighted.

Deregulation of CSMD1 targeted by microRNA-10b drives gastric cancer progression through the NF-κB pathway

Aim: This study aimed to investigate the oncogenic activity of microRNA-10b by targeting CUB and sushi multiple domains protein 1 (CSMD1) in human gastric cancer (GC) and the underlying mechanisms.

Methods: The expression of CSMD1 in human GC tissues was evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR), immunoblotting, and immunohistochemical analysis. The expressive abundance of microRNA-10b was detected by stem-loop RT-PCR. Molecular and cellular techniques, including lentiviral vector-mediated knockdown or overexpression, were used to elucidate the effect of microRNA-10b on the expression of CSMD1.

Results: CSMD1 was targeted and downregulated by microRNA-10b in human GC tissues and cells, and the down-regulated expression of CSMD1 contributed to poor survival. The knockdown of microRNA-10b expression inhibited cell proliferation in GC cells in vitro and tumor growth in vivo. The inhibition of microRNA-10b expression repressed invasion and migration of HGC27 cells and retarded GC cells metastasis to the liver in Balb/c nude mice. The up-regulated expression of microRNA-10b promoted the proliferation and metastasis of MKN74 cell in vitro. Intratumoral injection of microRNA-10b mimic also promoted the growth and metastasis of tumor xenografts in Balb/c nude mice. Mechanistically, microRNA-10b promoted the invasion and metastasis of human GC cells through inhibiting the expression of CSMD1, leading to the activation of the nuclear factor-κB (NF-κB) pathway that links inflammation to carcinogenesis, subsequently resulting in the upregulation of c-Myc, cyclin D1 (CCND1), and epithelial-mesenchymal transition (EMT) markers.

Conclusions: The findings established that microRNA-10b is an oncomiR that drives metastasis. Moreover, a set of critical tumor suppressor mechanisms was defined that microRNA-10b overcame to drive human GC progression.

Validation study of susceptibility loci for esophageal squamous cell carcinoma identified by GWAS in a Han Chinese subgroup from Eastern China

Esophageal squamous cell carcinoma (ESCC) occurs at a relatively high frequency in China and is one of the most prevalent cancers in the world. Genome-wide association studies (GWAS) have identified 24 single-nucleotide polymorphisms (SNPs) that could be associated with ESCC in Chinese patients. This retrospective study aimed to validate the association between these 24 SNPs and ESCC in a Han Chinese subgroup from East China. A total of 2280 and 1900 patients with ESCC (case group) and non-esophageal cancer (control group) were included from a single center. Genotyping of the 24 polymorphisms was performed using the Sequenom MassARRAY system. Unconditional logistic regression analyses were conducted for every polymorphism. It was found that rs12188136 (P=0.027, OR=1.158, 95% CI=1.016-1.319 for AG/AA) was associated with ESCC. Binary logistic regression analyses revealed a significant negative association of rs875339 in RORA (P=0.014, OR=0.762, 95% CI=0.613-0.947 for TT/CC). Under the dominant model, rs6854472 was slightly associated with ESCC risk (P=0.048, OR=1.192, 95% CI=1.002-1.418). Under the recessive model, a significant negative association was observed for rs875339 (P=0.010, OR=0.758, 95% CI=0.615-0.935). In a word, this large-scale replication study validated that rs12188136 and rs6854472 are associated with ESCC in a Han Chinese subgroup from Eastern China, and that rs875339 is negative associated with ESCC.

Effect of p-PAQR3Thr32 on PD-L1 expression and immune evasion in gastric cancer

e15571

Background: Therapies targeted to the immune checkpoint mediated by PD-1 and PD-L1 show antitumor activity in some solid tumors. We have now examined PD-L1 expression and its regulation in gastric cancer with p-PAQR3Thr32 protein. Methods: The expression of PD-L1 at the protein and mRNA levels in gastric cancer cell lines was examined by flow cytometry, real-time RT-PCR and western blot analysis, respectively. The expression of PD-L1 and p-PAQR3Thr32 protein in 319 surgically resected gastric cancer specimens was evaluated by immunohistochemical analysis. Results: The PD-L1 expression level was higher in gastric cancer cell lines positive for p-PAQR3Thr32 protein induced by glucose starvation than in those negative for the p-PAQR3Thr32 protein. Forced expression of p-PAQR3Thr32 protein in gastric cancer cells markedly increased PD-L1 expression, whereas endogenous PD-L1 expression in p-PAQR3Thr32 protein positive gastric cancer cells was attenuated by treatment with PAQR3 siRNAs. Furthermore, expression of PD-L1 was downregulated by inhibitors of the IRF1 and STAT1 in IFNs-PDL1 signaling pathway in gastric cancer cells positive for p-PAQR3Thr32 protein. At clinical tissue level, the expression level of PD-L1 was positively associated with the presence of p-PAQR3Thr32 protein in gastric cancer specimens. Moreover, the expression level of p-PAQR3Thr32 protein was negatively correlated with CD3, CD8, GZMA (CD8 T cell secretory factor) and positively correlated with CD68 (macrophage marker). Conclusions: Our findings that p-PAQR3Thr32 protein induced by glucose deficiency upregulate PD-L1 by activating IFNs-PDL1 signaling pathway in gastric cancer reveal a direct link between p-PAQR3Thr32 protein and PD-L1 expression. It is suggested that p-PAQR3Thr32 protein may be involved in tumor immunosuppression by inhibiting the proliferation and activity of CD8 T cells in gastric cancer tissues.

Antitumor properties of Salvianolic acid B against triple-negative and hormone receptor-positive breast cancer cells via ceramide-mediated apoptosis

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited treatment options. It is urgent to develop new therapeutics against this disease. Salvinolic acid B (Sal-B) is a leading bioactive component of Salvia miltiorrhiza Bunge, a well-known Chinese medicine for treating various diseases without appreciable adverse effects. To understand the antitumor properties of Sal-B against TNBC, we analyzed its effects on the cell viability, cell cycle and apoptosis of triple-negative MDA-MB-231 cells with the hormone receptor-positive MCF-7 cells as the control. The in vitro analysis showed that Sal-B could significantly reduce the cell viability and suppress the proliferation of both MDA-MB-231 and MCF-7 cells with decreased cyclin B1 expression, but with no noticeable cell cycle phase change. In mouse models, Sal-B markedly inhibited the growth, decreased the PCNA expression, and increased the cell apoptosis of MDA-MB-231 tumor xenografts. To understand the antitumor mechanisms, we analyzed the expression levels of ceramides, and anti-apoptotic (Bcl-xL and survivin) and pro-apoptotic (caspase-3 and caspase-8) proteins. We found that Sal-B enhanced the ceramide accumulation and inhibited the anti-apoptotic protein expression. Interestingly, the ceramide accumulation was accompanied by decreased expression of glucosylceramide and GM3 synthases, two key enzymes regulating ceramide metabolism. These findings indicate that Sal-B exerts its antitumor effects at least partially by inducing the ceramide accumulation and ceramide-mediated apoptosis via inhibiting the expression of glucosylceramide and GM3 synthases, which was independent of estrogen receptor α. Sal-B appears to be a promising therapeutic agent against TNBC.

Acetylation accumulates PFKFB3 in cytoplasm to promote glycolysis and protects cells from cisplatin-induced apoptosis

Enhanced glycolysis in cancer cells has been linked to cell protection from DNA damaging signals, although the mechanism is largely unknown. The 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) catalyzes the generation of fructose-2,6-bisphosphate, a potent allosteric stimulator of glycolysis. Intriguingly, among the four members of PFKFB family, PFKFB3 is uniquely localized in the nucleus, although the reason remains unclear. Here we show that chemotherapeutic agent cisplatin promotes glycolysis, which is suppressed by PFKFB3 deletion. Mechanistically, cisplatin induces PFKFB3 acetylation at lysine 472 (K472), which impairs activity of the nuclear localization signal (NLS) and accumulates PFKFB3 in the cytoplasm. Cytoplasmic accumulation of PFKFB3 facilitates its phosphorylation by AMPK, leading to PFKFB3 activation and enhanced glycolysis. Inhibition of PFKFB3 sensitizes tumor to cisplatin treatment in a xenograft model. Our findings reveal a mechanism for cells to stimulate glycolysis to protect from DNA damage and potentially suggest a therapeutic strategy to sensitize tumor cells to genotoxic agents by targeting PFKFB3.

Potential role of NDRG2 in reprogramming cancer metabolism and epithelial-to-mesenchymal transition

Epithelial-to-mesenchymal transition (EMT) allows a cell with epithelial characteristics to transdifferentiate into a cell with mesenchymal characteristics, which is recognized as a key priming event for the initiation and evolvement of cancer metastasis. Accumulating data have shown that aberrant cancer metabolism contributes to the execution of EMT and cancer metastasis through multiple pathological pathways. Recently, the N-MYC downstream-regulated gene 2 (NDRG2), as a tumor suppressor and metabolism-related gene in various cancers, has been widely noted. NDGR2 is associated with energy metabolism, especially glycose metabolism. Hence, we propose a hypothesis that EMT is repressed by NDRG2 via cancer metabolic reprogramming, and summarize the pathological processes and molecular pathways related to the regulation of NDRG2.

Soft-shelled turtle peptide modulates microRNA profile in human gastric cancer AGS cells

Cancer prevention using natural micronutrition on epigenetic mechanisms primarily revolves around plant extracts. However, the role of macronutrition, including animal peptides, on epigenetic modification in cancer has been elusive. In traditional Chinese medicine, the soft-shelled turtle has a long-history of being a functional food that strengthens immunity through unknown mechanisms. The present study aimed to investigate the impact of soft-shelled turtle peptide on microRNA (miRNA) expression in gastric cancer (GC) cells and to analyze the potential anticancer mechanisms for GC. Affymetrix GeneChip miRNA 3.0 Array and quantitative polymerase chain reaction were used to detect the miRNA expression profile in human GC AGS cells treated with the soft-shelled turtle peptide. The results demonstrated that 101 miRNAs (49 upregulated miRNAs and 52 downregulated miRNAs) were significantly differentially expressed in the AGS cells following soft-shelled turtle peptide treatment. Several tumor suppressor miRNAs were upregulated markedly, including miRNA-375, let-7d, miRNA-429, miRNA-148a/148b and miRNA-34a. Pathway analysis indicated that soft-shelled turtle peptide may function with anticancer properties through the Hippo signaling pathway and the forkhead box O signaling pathway. Therefore, these results demonstrated that soft-shelled turtle peptide has the capacity to influence cancer-related pathways through the regulation of miRNA expression in GC cells.

Progress in research of gastric signet ring cell carcinoma

Gastric signet ring cell carcinoma is a special type of gastric cancer. In recent years the incidence of gastric cancer has decreased, but the incidence of gastric signet ring cell carcinoma is still rising. Although a large number of studies reported the clinicopathologic features and oncogenesis of gastric signet ring cell carcinoma, the results are inconsistent. This article mainly discusses the clinicopathologic features, prognosis, and molecular characteristics of oncogenesis of gastric signet ring cell carcinoma to provide a basis and strategy for individualized treatment of this malignancy.

Epigenetic silencing of HIC1 promotes epithelial-mesenchymal transition and drives progression in esophageal squamous cell carcinoma

Downregulation of the novel tumor suppressor gene HIC1 (hypermethylated in cancer 1) occurs frequently in various tumors where it causes tumor progression and metastasis. In this study, we investigated a role of HIC1 in esophageal squamous cell carcinoma (ESCC) and the underlying mechanisms. Downregulation of HIC1 occurred in approximately 70% of primary ESCCs at both mRNA and protein level where it was associated significantly with vascular invasion, advanced clinical stage, lymph node metastasis, and poor disease free survival (DFS). The promoter methylation analyses suggested that loss of HIC1 expression was mediated by epigenetic mechanisms. Functional studies established that ectopic re-expression of HIC1 in ESCC cells inhibited cell proliferation, clonogenicity, cell motility, tumor formation and epithelial-mesenchymal transition (EMT). Our results decipher the mechanism through which HIC1 deficiency induce ESCC cells to undergo EMT and promote tumor progression and metastasis through activation of EphA2 signaling pathway. Together, loss of the regulation of EphA2 pathway through HIC1 epigenetic silencing could be an important mechanism in the ESCC progression. We identify a novel pathway that linking HIC1 downregulation to EphA2-inducing EMT in ESCC cells and may shed light on the development of novel anti-tumor therapeutics.

Duodenal Contents Reflux-Induced Laryngitis in Rats: Possible Mechanism of Enhancement of the Causative Factors in Laryngeal Carcinogenesis

Objectives:

The main factors considered responsible for the onset of laryngeal cancer are tobacco smoking and alcohol abuse. Recently, gastroesophageal reflux has also been implicated as a causative factor in several laryngeal disorders, including laryngeal cancer. However, the significance of gastroesophageal reflux in laryngeal cancer is controversial.

Methods:

We investigated the histologic features of the esophagus and larynx in a rat model of reflux of the duodenal contents. Cell proliferation was also evaluated in laryngeal samples by detection of Ki67 antigen.

Results:

In this reflux model, laryngitis with infiltration of inflammatory cells and proliferation of small mucous glands was evident from 10 weeks after operation, and basal cell hyperplasia around the epiglottis and hyperplastic changes in the larynx were detected at 30 weeks. No dysplastic or malignant lesions were detected in the laryngeal samples within the duration of the experiment, in spite of detection of malignancy in 31.3% of lesions in esophageal samples at 30 weeks. The Ki67 index at each week was significantly higher than that of the control animals.

Conclusions:

Previous studies have shown smoking and alcohol abuse to have refluxogenic effects. Reflux of duodenal contents causes laryngitis. Reflux does not appear to be an independent risk factor for laryngeal carcinogenesis, but it may enhance the acknowledged etiologic risk factors, namely, smoking and alcohol abuse, by promoting cell proliferation.

RRM1 *151A>T, RRM1 -756T>C, and RRM1 -585T>Gis associated with increased susceptibility of lung cancer in Chinese patients

Ribonucleotide reductase M1 (RRM1) is a crucial gene in DNA repair. Recent studies have shown that RRM1 expression can be a powerful predictor of survival or chemotherapy sensitivity in patients presenting with carcinomas who are treated with adjuvant gemcitabine-based chemotherapy including lung cancer. However, the relationship between the single nucleotide polymorphisms (SNP) of RRM1 and the susceptibility of lung cancer to chemotherapy has not been well addressed. We detected six tag SNPs of RRM1 genotypes in a cohort of 1007 patients with primary lung cancer and 1007 age- and sex-matched population controls using SNaPshot detection technology. Logistic regression, odds ratios (OR), and 95% confidence intervals were calculated to estimate lung cancer risk associated with SNP genotypes and haplotypes, after adjusting for case-control matching factors. Compared with the T/T and A/T genotype of RRM1 *151A>T, the A/A genotype had an increased risk for overall lung cancer (adjusted OR, 1.33). Additionally, the T/T+T/C genotypes of RRM1 -756T>C were risk factors that increased the susceptibility to lung cancer (adjusted OR 1.54, as compared with the C/C genotype). While the T/T+G/T genotypes of RRM1 -585T>G behaved as protective factors to increase the susceptibility to lung cancer (adjusted OR 0.44, as compared with the C/C genotype). In summary, this is the first study to systematically identify the relationship between the polymorphisms of RRM1 and individual susceptibility to lung cancer. It is anticipated that the RRM1 *151A>T, RRM1 -756T>C, and RRM1 -585T>G polymorphisms will improve the predictive prognosis of lung cancer sensitivity.

Ndrg2 promoter hypermethylation triggered by helicobacter pylori infection correlates with poor patients survival in human gastric carcinoma

N-myc downstream regulated gene 2 (Ndrg2) is a candidate suppressor of cancer metastasis. We found that Ndrg2 promoter was frequently hypermethylated in gastric cancer cell lines and in 292 gastric tumor tissues. This resulted in down-regulation of Ndrg2 mRNA and protein. Ndrg2 promoter methylation was associated with H. pylori infection and worse prognosis of gastric cancer patients, which is an independent prognostic factor for the disease-free survival (DFS). We found that H. pylori silenced Ndrg2 by activating the NF-κB pathway and up-regulating DNMT3b, promoting gastric cancer progression. These findings uncover a previously unrecognized role for H. pylori infection in gastric cancer.

Chemoprevention of Low-Molecular-Weight Citrus Pectin (LCP) in Gastrointestinal Cancer Cells

Background & Aims: Low-molecular-weight citrus pectin (LCP) is a complex polysaccharide that displays abundant galactosyl (i.e., sugar carbohydrate) residues. In this study, we evaluated the anti-tumor properties of LCP that lead to Bcl-xL -mediated dampening of apoptosis in gastrointestinal cancer cells.

Methods: We used AGS gastric cancer and SW-480 colorectal cancer cells to elucidate the effects of LCP on cell viability, cell cycle and apoptosis in cultured cells and tumor xenografts.

Results: Significantly decreased cell viabilities were observed in LCP treated AGS and SW-480 cells (P<0.05). Cell cycle-related protein expression, such as Cyclin B1, was also decreased in LCP treated groups as compared to the untreated group. The AGS or SW-480 cell-line tumor xenografts were significantly smaller in the LCP treated group as compared the untreated group (P<0.05). LCP treatment decreased Galectin-3 (GAL-3) expression levels, which is an important gene in cancer metastasis that results in reversion of the epithelial-mesenchymal transition (EMT), and increased suppression of Bcl-xL and Survivin to promote apoptosis. Moreover, results demonstrated synergistic tumor suppressor activity of LCP and 5-FU against gastrointestinal cancer cells both in vivo and in vitro.

Conclusions: LCP effectively inhibits the growth and metastasis of gastrointestinal cancer cells, and does so in part by down-regulating Bcl-xL and Cyclin B to promote apoptosis, and suppress EMT. Thus, LCP alone or in combination with other treatments has a high potential as a novel therapeutic strategy to improve the clinical therapy of gastrointestinal cancer.

PAQR3 expression is downregulated in human breast cancers and correlated with HER2 expression

PAQR3 is a newly discovered tumor suppressor and its functional role in breast cancer has not been well characterized. We report here that PAQR3 is associated with the progression and survival of human patients with breast cancer, as well as cell proliferation and migration of human breast cancer cells. PAQR3 mRNA level was robustly downregulated in human breast cancer samples compared with their corresponding para-cancerous histological normal tissues (n = 82, P < 0.0001). The mRNA level of PAQR3 was negatively correlated with HER2 expression (P < 0.0001) and disease-free survival of the patients (P < 0.0001). PAQR3 overexpression inhibited cell proliferation, colony formation and migration of breast cancer cells including MCF7, SKBR3, MDA-MD-231, MDA-MD-468 and MDA-MD-453 cells. Knockdown of PAQR3 in MDA-MD-231 cells elevated cell proliferation and migration. Inhibition of HER2 by trastuzumab increased PAQR3 expression in SKBR3 cells. In conclusion, PAQR3 expression is frequently downregulated in human breast cancers inversely correlated with HER2 expression. PAQR3 is able to modulate the proliferation and migration of breast cancer cells. Our data indicate that PAQR3 functions as a tumor suppressor in the development of human breast cancers.

Fbxw7 Tumor Suppressor: A Vital Regulator Contributes to Human Tumorigenesis

Rapidly accumulating data indicate that F-box/WD repeat-containing protein 7 (Fbxw7) is one of the most frequently mutated genes in human cancers and regulates a network of crucial oncoproteins. These studies have generated important new insights into tumorigenesis and may soon enable therapies targeting the Fbxw7 pathway. We searched PubMed, Embase, and ISI Web of Science databases (1973-2015, especially recent 5 years) for articles published in the English language using the key words "Fbxw7," "Fbw7," "hCDC4," and "Sel-10," and we reviewed recent developments in the search for Fbxw7. Fbxw7 coordinates the ubiquitin-dependent proteolysis of several critical cellular regulators, thereby controlling essential processes, such as cell cycle, differentiation, and apoptosis. Fbxw7 contains 3 isoforms (Fbxw7α, Fbxw7β, and Fbxw7γ), and they are differently regulated in subtract recognition. Besides those, Fbxw7 activity is controlled at different levels, resulting in specific and tunable regulation of the abundance and activity of its substrates in a variety of human solid tumor types, including glioma malignancy, nasopharyngeal carcinoma, osteosarcoma, melanoma as well as colorectal, lung, breast, gastric, liver, pancreatic, renal, prostate, endometrial, and esophageal cancers. Fbxw7 is strongly associated with tumorigenesis, and the mechanisms and consequences of Fbxw7 deregulation in cancers may soon enable the development of novel therapeutic approaches.

miR-21 regulates tumor progression through the miR-21-PDCD4-Stat3 pathway in human salivary adenoid cystic carcinoma

miR-21, which is a putative tumor onco-miR and frequently overexpressed microRNA in various tumors, has been linked to tumor progression through targeting of tumor-suppressor genes. In this study, we sought to determine whether miR-21 has any role on tumor progression of salivary adenoid cystic carcinoma (SACC) and the possible mechanisms. We found that the level of miR-21 expression was significantly higher in SACC than that in normal salivary tissues, and it is also higher in tumors with metastasis than that without metastasis. Using an anti-miR-21 inhibitor in an in vitro model, downregulation of miR-21 significantly decreased the capacity of invasion and migration of SACC cells, whereas a pre-miR-21 increased the capacity of invasion and migration of SACC cells. To explore the potential mechanisms by which miR-21 regulate invasion and migration, we identified one direct miR-21 target gene, programmed cell death 4 (PDCD4), which has been implicated in invasion and metastasis. The suppression of miR-21 in metastatic SACC-LM cells significantly increased the report activity of PDCD4 promoter and the expression of PDCD4 protein. This subsequently resulted in downregulation of the p-STAT3 protein. The level of miR-21 expression positively related to the expression of PDCD4 protein and negatively related to the expression of p-STAT3 protein in SACC specimens, respectively, indicating the potential role of the STAT3-miR-21-PDCD4 pathway in these tumors. Dysregulation of miR-21 has an important role in tumor growth and invasion by targeting PDCD4. Therefore, suppression of miR-21 may provide a potential approach for the treatment of advanced SACC patients.

PHD3 Stabilizes the Tight Junction Protein Occludin and Protects Intestinal Epithelial Barrier Function

Prolyl hydroxylase domain proteins (PHDs) control cellular adaptation to hypoxia. PHDs are found involved in inflammatory bowel disease (IBD); however, the exact role of PHD3, a member of the PHD family, in IBD remains unknown. We show here that PHD3 plays a critical role in maintaining intestinal epithelial barrier function. We found that genetic ablation of Phd3 in intestinal epithelial cells led to spontaneous colitis in mice. Deletion of PHD3 decreases the level of tight junction protein occludin, leading to a failure of intestinal epithelial barrier function. Further studies indicate that PHD3 stabilizes occludin by preventing the interaction between the E3 ligase Itch and occludin, in a hydroxylase-independent manner. Examination of biopsy of human ulcerative colitis patients indicates that PHD3 is decreased with disease severity, indicating that PHD3 down-regulation is associated with progression of this disease. We show that PHD3 protects intestinal epithelial barrier function and reveal a hydroxylase-independent function of PHD3 in stabilizing occludin. These findings may help open avenues for developing a therapeutic strategy for IBD.

Role of isocitrate dehydrogenase 1/2 (IDH 1/2) gene mutations in human tumors

In recent years, frequent isocitrate dehydrogenase 1/2 (IDH1/IDH2) gene mutations were found in a variety of tumors, which specifically alter arginine residues of catalytic active site in IDH1/IDH2 and confer new enzymatic function of directly catalyzing alpha-ketoglutarate (α-KG) to R-2-hydroxyglutarate (2-HG). 2-HG could competitively inhibit α-KG-dependent enzymes and might therefore contribute to tumorigenesis. In addition, mutation status of IDH1/IDH2 is closely related to the progress and prognosis of certain tumors. Thus IDH1/IDH2 is considered to be a promising biomarker for early diagnosis and prognosis and targeted therapy. In this study, the current research on IDH1/IDH2 mutation, especially the mechanisms and clinical characteristics related to tumor, are reviewed.

The Endoplasmic Reticulum Stress Sensor IRE1α in Intestinal Epithelial Cells Is Essential for Protecting against Colitis

Intestinal epithelial cells (IECs) have critical roles in maintaining homeostasis of intestinal epithelium. Endoplasmic reticulum (ER) stress is implicated in intestinal epithelium homeostasis and inflammatory bowel disease; however, it remains elusive whether IRE1α, a major sensor of ER stress, is directly involved in these processes. We demonstrate here that genetic ablation of Ire1α in IECs leads to spontaneous colitis in mice. Deletion of IRE1α in IECs results in loss of goblet cells and failure of intestinal epithelial barrier function. IRE1α deficiency induces cell apoptosis through induction of CHOP, the pro-apoptotic protein, and sensitizes cells to lipopolysaccharide, an endotoxin from bacteria. IRE1α deficiency confers upon mice higher susceptibility to chemical-induced colitis. These results suggest that IRE1α functions to maintain the intestinal epithelial homeostasis and plays an important role in defending against inflammation bowel diseases.

Circulating miRNAs is a potential marker for gefitinib sensitivity and correlation with EGFR mutational status in human lung cancers

miRNA expression is deregulated in non-small cell lung cancer (NSCLC), and some miRNAs are associated with gefitinib sensitivity. Here, we investigated if circulating miRNAs could be a useful biomarker for the prediction of EGFR mutation and the patient's prognosis. The differential miRNAs related to gefitinib sensitivity were screened and identified by microRNA array. Using Taqman-based real-time RT-PCR, we analyzed the expression of selected miRNAs in tumor tissues and plasma of 150 NSCLC patients. Kaplan-Meier survival analysis and Cox proportional hazards regression were used to determine the association between miRNAs expression and survival. Receiver operating characteristic curve analysis was also performed. Compared with PC9 cell line, 41 microRNAs detected by microarray were significantly differentially expressed in A549 and H1299 cells. The 5 selected hsa-miRNAs were all found differently expressed between wild and mutant EGFR carriers (all P<0.01). Down-regulation of 5 selected miRNAs were independently associated with lymphatic invasion (all P<0.01) and clinical stage (all P<0.01), respectively. Both down-regulation of has-miR-195 (P=0.012) and has-miR-21 (P=0.004) were associated with poor differentiation. All up-regulation of 5 has-miRNAs were associated with smoking (All P<0.05). 5 hsa-miRNAs were up-regulated both in plasma and tissue samples. A model including 4 hsa-miRNAs may predict EGFR mutational status and gefitinib-sensitivity (both AUC: 0.869). Plasma levels of has-miR-125b expression were associated with disease-free survival (P=0.033) and overall survival in the patients (P=0.028). In a word, Circulating 5 selected miRNAs may especially be useful in predicting EGFR mutation, and circulating hsa-miR-125b may have prognostic values in NSCLC patients.

SIRT3-dependent GOT2 acetylation status affects the malate-aspartate NADH shuttle activity and pancreatic tumor growth

The malate-aspartate shuttle is indispensable for the net transfer of cytosolic NADH into mitochondria to maintain a high rate of glycolysis and to support rapid tumor cell growth. The malate-aspartate shuttle is operated by two pairs of enzymes that localize to the mitochondria and cytoplasm, glutamate oxaloacetate transaminases (GOT), and malate dehydrogenases (MDH). Here, we show that mitochondrial GOT2 is acetylated and that deacetylation depends on mitochondrial SIRT3. We have identified that acetylation occurs at three lysine residues, K159, K185, and K404 (3K), and enhances the association between GOT2 and MDH2. The GOT2 acetylation at these three residues promotes the net transfer of cytosolic NADH into mitochondria and changes the mitochondrial NADH/NAD(+) redox state to support ATP production. Additionally, GOT2 3K acetylation stimulates NADPH production to suppress ROS and to protect cells from oxidative damage. Moreover, GOT2 3K acetylation promotes pancreatic cell proliferation and tumor growth in vivo. Finally, we show that GOT2 K159 acetylation is increased in human pancreatic tumors, which correlates with reduced SIRT3 expression. Our study uncovers a previously unknown mechanism by which GOT2 acetylation stimulates the malate-aspartate NADH shuttle activity and oxidative protection.

Methylated TIMP-3 DNA in body fluids is an independent prognostic factor for gastric cancer

CONTEXT

Fluid methylated DNA may be a suitable biomarker for cancer patients.

OBJECTIVE

To investigate whether circulating methylated tissue inhibitor of metalloproteinase 3 (TIMP-3) DNA in body fluids is a useful prognostic biomarker in gastric cancer (GC).

DESIGN

TIMP-3 methylation was detected by real-time methylation-specific polymerase chain reaction in tumor tissues, paired preoperative peritoneal washes (PPWs), and paired serum samples from 92 GC patients.

RESULTS

The frequency of TIMP-3 methylation was significantly elevated in GC tissues (63.04%; 58 of 92) compared with that in paired adjacent normal tissue (4.3%; 4 of 92) (P < .001). TIMP-3 methylation correlated closely with peritoneal metastasis and TNM stage (all P < .001). The frequency of TIMP-3 methylation in preoperative peritoneal washes and serum samples was 53.3% (49 of 92) and 58.7% (54 of 92), respectively. The Aζ values of the receiver operator characteristic curve for methylated TIMP-3 were 0.966 and 0.922 for serum and preoperative peritoneal washes, respectively, compared with those in GC tissues. The patients with elevated methylated TIMP-3 levels in body fluids had poorer disease-free survival rates than those without (all P < .001). Cox regression analysis showed that detection of methylated TIMP-3 DNA in body fluids was an independent risk factor for GC patients, with a remarkable decrease in disease-free survival 30 months after surgical resection of the gastric tumor.

CONCLUSION

Presence of methylated TIMP-3 DNA in body fluids is a useful biomarker for predicting the progression and prognosis of GC patients.

Elevated levels of preoperative circulating CD44⁺ lymphocytes and neutrophils predict poor survival for non-small cell lung cancer patients

BACKGROUND

Certain circulating cells have been shown to predict the clinical outcome of several cancers. The objective of this study was to identify clinical, hematological and immunological predictors of prognosis in non-small cell lung cancer (NSCLC) patients.

METHODS

A retrospective study on a prevalent cohort of 225 NSCLC patients hospitalized at the Zhejiang Province Cancer Hospital (ZPCH) was conducted from August 1, 2006 to April 15, 2008. Circulating lymphocytes were measured by flow cytometry. WBC count and classification in peripheral blood were measured with a Coulter counter. We calculated the proportion of patients surviving after first hospital admission and hazard ratios (HR) using the Cox proportional hazards model.

RESULTS

Elevated levels of preoperative circulating CD44(+) lymphocytes, WBCs and neutrophils indicated low cumulative survival. Clinical stage (HR: 2.292; 95% confidence interval (CI): 1.34-3.91, P=0.002), neutrophils (HR: 1.877; 95% CI: 1.34-2.62, P<0.001) and CD44(+) lymphocytes (HR: 1.018; 95% CI: 1.00-1.03, P=0.002) are independent predictors of survival in NSCLC patients, respectively. Elevated levels of CD44(+) lymphocytes and neutrophils correlated with distant metastasis and prognosis in NSCLC patients with stage III/IV, respectively.

CONCLUSIONS

CD44(+) lymphocytes along with neutrophils could serve as an independent prognostic marker for NSCLC patients.

A Golgi-specific protein PAQR3 is closely associated with the progression, metastasis and prognosis of human gastric cancers

BACKGROUND

The aim of this study is to determine whether PAQR3, a protein specifically localized in the Golgi apparatus, is associated with tumor progression, metastasis and survival of human patients with gastric cancer.

PATIENTS AND METHODS

PAQR3 expression status was investigated in a large panel of gastric cancer (n = 300) and their corresponding para-cancerous histological normal tissues (PCHNT) at both mRNA and protein levels. The correlation of PAQR3 expression levels with clinical features such as metastasis and prognosis was analyzed. The effect of PAQR3 on the growth and migration of gastric cancer cells was also determined.

RESULTS

PAQR3 was frequently down-regulated in gastric cancer samples compared with PCHNT at both mRNA and protein levels (both P < 0.0001). The expression level of PAQR3 was negatively correlated with Helicobacter pylori infection (P < 0.0001), tumor size (P < 0.0001), tumor stage (P < 0.0001), venous and lymphatic invasion (P < 0.0001), distant and nodal metastasis (P < 0.0001), and patient survival (P < 0.0001). Down-regulation of PAQR3 was highly correlated with increased epithelial-mesenchymal transition (EMT) in gastric cancer samples. In addition, PAQR3 overexpression was able to negatively modulate cell proliferation, migration and EMT of gastric cancer cells.

CONCLUSION

PAQR3 is markedly down-regulated in human gastric cancers. PAQR3 expression level is closely associated with the progression and metastasis of gastric cancers. PAQR3 is also a new genetic signature that can predict the prognosis of the patients with gastric cancer.

Regulation of G6PD acetylation by SIRT2 and KAT9 modulates NADPH homeostasis and cell survival during oxidative stress

Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme in the pentose phosphate pathway (PPP) and plays an essential role in the oxidative stress response by producing NADPH, the main intracellular reductant. G6PD deficiency is the most common human enzyme defect, affecting more than 400 million people worldwide. Here, we show that G6PD is negatively regulated by acetylation on lysine 403 (K403), an evolutionarily conserved residue. The K403 acetylated G6PD is incapable of forming active dimers and displays a complete loss of activity. Knockdown of G6PD sensitizes cells to oxidative stress, and re-expression of wild-type G6PD, but not the K403 acetylation mimetic mutant, rescues cells from oxidative injury. Moreover, we show that cells sense extracellular oxidative stimuli to decrease G6PD acetylation in a SIRT2-dependent manner. The SIRT2-mediated deacetylation and activation of G6PD stimulates PPP to supply cytosolic NADPH to counteract oxidative damage and protect mouse erythrocytes. We also identified KAT9/ELP3 as a potential acetyltransferase of G6PD. Our study uncovers a previously unknown mechanism by which acetylation negatively regulates G6PD activity to maintain cellular NADPH homeostasis during oxidative stress.

Enhanced serum methylated p16 DNAs is associated with the progression of gastric cancer

OBJECTIVE

The present study is to evaluate the effect of methylated p16 on the progression in patients with gastric cancer (GC), and develop a useful biomarker for predicting patient's prognosis.

DESIGN AND METHODS

Methylation status of p16 in GC, their corresponding para-cancerous histological normal tissues (PCHNTs), preoperative peritoneal washes (PPWs) and serum were assessed using real-time methylation specific-PCR (MSP).

RESULTS

The frequency of p16 methylation was significantly higher in GC tissues (85.9%; 79/92) than that in paired PCHNTs (12.0%; 11/92) (P<0.0001). p16 methylation correlated closely with lymph node metastasis, peritoneal metastasis, TNM stage, et al (all P<0.05). Both frequency of p16 methylation in PPWs and serum were 79.7% (63/92). The Aζ value of the receiver-operator characteristic curve for methylated p16 was 0.899 for serum and PPWs, compared to that in GC tissues. The patients with elevated methylated p16 levels in tumor tissues had poorer disease-free survival (DFS) rates than those without (P=0.042). There is a narrow significant difference in median survival time of more than 30 months between patients with and without preoperatively detectable methylated p16 in serum (P=0.057). Methylated p16 in PPWs revealed no significant association with survival (P=0.129). Cox regression analysis showed that serum methylated p16 DNAs was an independent risk factor for GC patients, with a remarkable decrease in DFS 30 months after surgical resection of the gastric tumor.

CONCLUSIONS

Serum methylated p16 DNAs might serve as a potential biomarker for the progression and a prognostic factor in gastric cancer patients.

The role of TET family proteins and 5-hydroxymethylcytosine in human tumors

Tumorigenesis correlates with hypermethylation of tumor suppressors and hypomethylation of oncogenes. DNA methyltransferases (DNMTs) catalyze DNA methylation, and mutations and aberrant expression in DNMT genes are found in multiple human tumors. The discovery of the DNA demethylation function of TET proteins has opened up new avenues for the study of DNA methylation regulation. TET proteins regulate the DNA demethylation pathway through oxidizing 5-mC into 5-hmC, 5-fC, and 5-aC. TET genes have been reported to be frequently mutated in hematopoietic malignancies and are associated with the malignant transformation of cells. Loss-of-function mutations in TET genes have not been reported in human solid tumors. However, 5-hmC has been found to be reduced in various solid tumors, indicating that TET genes may contribute to cellular transformation via regulation of DNA demethylation. As a new epigenetic modification, 5-hmC may be a useful biomarker for the diagnosis of cancers. To better understand the roles of TET and 5-hmC in tumors, the biological functions of TET and 5-hmC should be studied further.

The overexpression of VEGF in esophageal cancer is associated with a more advanced TMN stage: a meta-analysis

OBJECTIVE

The aim of this study was to quantitatively assess the impact of VEGF overexpression on prognosis in patients with esophageal cancer (EC).

METHODS

A meta-analysis was performed on studies reporting overall survival (OS) or clinicopathological parameters to compare the outcomes of EC patients with VEGF overexpression to the outcomes of patients without VEGF overexpression.

RESULTS

There was a significantly increased risk for patients with VEGF overexpression to have an advanced stage of the disease (III and IV) with an odds ratio (OR) of 2.14. Additionally, patients with VEGF overexpression had a 2.03-fold increased risk for distant metastasis and shorter OS (HR=1.55).

CONCLUSIONS

VEGF overexpression is associated with a more advanced TMN stage and shorter OS in EC patients.

The impact of E-cadherin expression on the prognosis of esophageal cancer: a meta-analysis

E-cadherin is a 120-KD transmembrane calcium-dependent cell adhesion protein that has been demonstrated drownregulated in a large amount of invasive tumors. However, its effect on the prognosis of esophageal cancer (EC) remains controversial. All the relevant English articles that reported survival data or clinicopathological parameters were enrolled in this meta-analysis. A total of 24 studies, including 2691 cases, were included in this study. Twelve studies containing 1669 cases were enrolled to synthesize with hazard ratio (HR) and its 95% confidence interval (CI). The pooled HR for all 12 studies enrolled in this meta-analysis was 1.33 (95% CI 1.16-1.52; z = 3.99, P = 0.00). When the study measured by enzyme-linked immunosorbent assay is excluded, the pooled HR-evaluated E-cadherin to reduce the expression in EC, and in esophageal squamous cell carcinoma was 1.39 (95% CI 1.22-1.58; z = 5.08, P = 0.00) and 1.38 (95% CI 1.21-1.56; z = 4.87, P = 0.00), respectively. The risk of reduced E-cadherin expression on poor differentiation degree was 1.636 (95% CI 1.33-2.02). The pooled odds ratio of reduced E-cadherin expression on deeper tumor invasion, lymph node metastasis, and higher clinical stage were 2.63 (95% CI 1.75-3.94), 1.77 (95% CI 1.06 -2.97), and 3.39 (95% CI 1.85-6.23). Reduced E-cadherin expression detected by immunohistochemistry could be a valid prognostic marker in patients with EC, especially in patients with esophageal squamous cell carcinoma. Reduced E-cadherin expression is significantly associated with poorer differentiation degree.

Down-regulation of PTEN expression modulated by dysregulated miR-21 contributes to the progression of esophageal cancer

BACKGROUND AND AIM

miR-21, a putative tumor oncomiR, is a frequently overexpressed miRNA in a variety of tumors. Because it targets tumor-suppressor genes it has been linked to tumor progression. In this study we investigated the role of miR-21 in esophageal squamous cell carcinoma (ESCC), and its possible mechanism.

METHODS

Expression of miR-21 was detected by stem-loop RT-PCR in tissue from 76 invasive ESCC at stage I-IV and in their corresponding para-cancerous histological normal tissues (PCHNT). Thirty endoscopic esophageal mucosal biopsy specimens from non-tumor patients were used as controls. Expression of PTEN in 76 paired ESCC and PCHNT was investigated by real-time RT-PCR and an immunohistochemical method, respectively. Paired tumor and PCHNT specimens of 20 ESCC cases were randomly selected for western blot analysis. The effect of miR-21 on PTEN expression was assessed in the ESCC cell line with an miR-21 inhibitor to reduce miR-21 expression. Furthermore, the roles of miR-21 in cell biology were analyzed by use of miR-21 inhibitor-transfected cells.

RESULTS

Stem-loop RT-PCR revealed miR-21 was significantly overexpressed in ESCC tissues and cell lines. Overexpression of miR-21 correlated with tumor status, lymph node metastasis, and clinical stage. We demonstrated that knockdown of miR-21 significantly increased expression of PTEN protein. Consequent PTEN expression reduced cell proliferation, invasion, and migration.

CONCLUSIONS

Our findings suggest that miR-21 could be a potential oncomiR, probably by regulation of PTEN, and a novel prognostic factor for ESCC patients.

[Effect of miRNA-106a expression on the prognosis of patients with esophageal squamous cell carcinoma]

OBJECTIVE

To study the expression of miRNA-106a gene in esophageal squamous cell carcinoma (ESCC) and its association with clinicopathological features and prognosis of ESCC patients.

METHODS

Real-time fluorescence quantitative polymerase chain reaction (PCR) assay was used to determine the expression of miRNA-106a gene in esophageal cancer tissue and corresponding normal mucosa of 81 cases. Immunohistochemical technique was applied to detect the expression of p53, human epidermal growth factor receptor 2 (HER-2), DNA topoisomerase II (Topo II) and multidrug resistance-associated protein (MRP). The association of miRNA-106a expression with clinicopathological features, expression of related proteins, and prognosis of the patients was analyzed.

RESULTS

Among the 81 cases, under-expression of miRNA-106a gene was found in 48 cases (59.3%), normal expression in 22 cases (27.2%), and overexpression in 11 cases (13.6%). The expression of miRNA-106 gene was significantly associated with lymph node metastasis, pathological stage, and nerve invasion (all P < 0.05), significantly associated with expression of p53 (P = 0.006), and not significantly associated with expressions of HER-2, Topo II and MRP proteins (all P > 0.05). The expression of miRNA-106a gene was also significantly associated with progression-free survival (PFS, P = 0.032), but not significantly with overall survival (OS, P = 0.486). The results of Cox multivariate regression analysis showed that the PFS of ESCC patients was significantly correlated with lymph node metastasis (P = 0.029), but not correlated with the age, gender, tumor length, T stage, degree of differentiation, nerve invasion, and miRNA-106a expression (all P > 0.05).

CONCLUSIONS

In esophageal squamous cell carcinomas, the miRNA-106a gene is under-expressed, with tumor suppressor function, and may be regarded as a biological marker to assess the prognosis in patients with esophageal squamous cell carcinoma.

Overexpression of ILK1 in breast cancer associates with poor prognosis

Integrin-linked kinase 1 (ILK1), a member of the serine/threonine kinases, has been demonstrated to be associated with numerous biological and pathological processes. However, the role of ILK1 in breast cancer has not been thoroughly elucidated. The purpose of this study was to assess ILK1 expression and to explore its contribution to breast cancer. The ILK1 mRNA expression was measured by real-time quantitative reverse transcriptase-polymerase chain reaction. In addition, ILK1 expression was analyzed by immunohistochemistry in 163 clinicopathologically characterized breast cancer cases. The relationship between ILK1 expression and clinicopathological features was analyzed by appropriate statistics. Kaplan-Meier analysis and Cox proportional hazard regression models were used to investigate the correlation between ILK1 expression and prognosis of breast cancer patients. The relative mRNA expression of ILK1 was significantly higher in breast cancer tissues than in adjacent noncancerous tissues (P < 0.001). In addition, ILK1 expression was significantly correlated with tumor size (P = 0.016), grade (P = 0.024), stage (P = 0.029), lymph node metastases (P = 0.007), and estrogen receptor status (P = 0.002). Kaplan-Meier analysis indicated that patients with high ILK1 expression had poor overall survival (P < 0.001). Multivariate analysis showed that high ILK1 expression was an independent predictor of overall survival. In conclusion, our data suggest for the first time that the increased expression of ILK1 in breast cancer is associated significantly with aggressive progression and poor prognosis. ILK1 may be an important molecular marker for predicting the carcinogenesis, progression, and prognosis of breast cancer.

Circulating Methylated XAF1 DNA Indicates Poor Prognosis for Gastric Cancer

BACKGROUND

Methylated DNA in fluids may be a suitable biomarker for cancer patients. XAF1 has been shown to be frequently down-regulated in human gastric cancer (GC). Here, we investigated if XAF1 methylation in GC could be a useful biomarker.

METHODS

Real-time RT-PCR was used to detect XAF1 mRNA expression; immunohistochemistry and western blot were used to examine XAF1 protein expression in GC tissues (n = 202) and their corresponding para-cancerous histological normal tissues (PCHNTs). Real-time methylation specific-PCR was used to investigate XAF1 promoter methylation in the same panel of GC tissues, their PCHNTs and sera.

RESULTS

We confirmed frequent XAF1 down-regulation in both mRNA and protein levels in GC tissues as compared to normal controls and PCHNTs. XAF1 hypermethylation was evidenced in 83.2% (168/202) of GC tissues and 27.2% (55/202) of PCHNTs, while no methylation was detected in the 88 normal controls. The methylation level in GC tissues was significantly higher than that in PCHNTs (p<0.05). The hypermethylation of XAF1 significantly correlated with the down-regulation of XAF1 in GC tissues in both mRNA and protein levels (p<0.001 each). Moreover, we detected high frequency of XAF1 methylation (69.8%, 141 out of 202) in the sera DNAs from the same patients, while the sera DNAs from 88 non-tumor controls were negative for XAF1 methylation. The XAF1 methylation in both GC tissues and in the sera could be a good biomarker for diagnosis of GC (AUC = 0.85 for tissue and AUC = 0.91 for sera) and significantly correlated with poorer prognosis (p<0.001). In addition, after-surgery negative-to-positive transition of XAF1 methylation in sera strongly associated with tumor recurrence.

CONCLUSIONS

1) Dysfunction of XAF1 is frequent and is regulated through XAF1 promoter hypermethylation; 2) Detection of circulating methylated XAF1 DNAs in the serum may be a useful biomarker in diagnosis, evaluating patient's outcome (prognosis and recurrence) for GC patients.