PPARα phosphorylation regulates colorectal tumor immune escape.

A high level of PD-L1 in cancer cells promotes tumor immune escape and inhibits tumor immunotherapy. Although PD-L1 gene expression is upregulated by multiple pathways, its gene transcriptional repression is still unclear. Here we found that loss of PPARα, one of the peroxisome-proliferator-activated receptors (PPARs) family members, promoted colorectal tumor immune escape. Mechanistically, PPARα directly bound to the PD-L1 promoter resulting in its gene transcriptional repression, which in turn increased T cell activity, and PPARα agonist enhanced this event. However, ERK induced PPARα-S12 phosphorylation leading to blockade of PPARα-mediated PD-L1 transcriptional repression, and the combination of ERK inhibitor with PPARα agonist significantly inhibited tumor immune escape. These findings suggest that the ERK-PPARα pathway inhibited PD-L1 gene transcriptional repression and promoted colorectal tumor immune escape.

Taxonomic, Phylogenomic and Bioactivity Profiling of Novel Phycosphere Bacterium from Model Cyanobacterium Synechococcus elongatus PCC 7942.

Phycosphere niches host rich microbial consortia that harbor dynamic algae-bacteria interactions with fundamental significance in varied natural ecosystems. Hence, culturing the uncultured microbial majority of the phycosphere microbiota is vital for deep understanding of the intricate mechanisms governing the dynamic interactions, and also to provide novel and rich microbial resources, and to discover new natural bioactive metabolites. Synechococcus elongatus PCC 7942 is a robust model cyanobacterium widely used in environment, synthesis biology, and biotechnology research. To expand the number of novel phycosphere species that were brought into culture and to discover the natural bioactivities, we presented a new yellow-pigmented bacterium named ABI-127-1, which was recovered from the phycosphere of PCC 7942, using an optimized bacterial isolation procedure. Combined polyphasic taxonomic and phylogenomic characterization was performed to confidently identify the new isolate as a potential novel species belonging to the genus Qipengyuania. The observed bioactivity of strain ABI-127-1 with promoting potential towards the growth and CO2 fixation efficiency of the host microalgae was measured. Additionally, the bacterial production of active bioflocculant exopolysaccharides was evaluated after culture optimization. Thus, these findings revealed the potential environmental and biotechnological implications of this new microalgae growth-promoting bacterium isolated from the phycosphere microenvironment.

The Emerging Roles of IL-36, IL-37, and IL-38 in Diabetes Mellitus and its Complications.

Diabetes mellitus is a metabolic disease caused by a combination of genetic and environmental factors. The importance of the inflammatory response occurring in the pancreas and adipose tissue in the occurrence and progression of diabetes has been gradually accepted. Excess blood glucose and free fatty acids produce large amounts of inflammatory cytokines and chemokines through oxidative stress and endoplasmic reticulum stress. There is sufficient evidence that proinflammatory mediators, such as interleukin (IL)-1ß, IL-6, macrophage chemotactic protein-1, and tumor necrosis factor-α, are engaged in insulin resistance in peripheral adipose tissue and the apoptosis of pancreatic ß-cells. IL-36, IL-37, and IL-38, as new members of the IL-1 family, play an indispensable role in the regulation of immune system homeostasis and are involved in the pathogenesis of inflammatory and autoimmune diseases. Recently, the abnormal expression of IL-36, IL-37, and IL-38 in diabetes has been reported. In this review, we discuss the emerging functions, potential mechanisms, and future research directions on the role of IL-36, IL-37, and IL-38 in diabetes mellitus and its complications.

Role of autophagy on cancer immune escape.

Autophagy is catabolic process by degradation of intracellular components in lysosome including proteins, lipids, and mitochondria in response to nutrient deficiency or stress such as hypoxia or chemotherapy. Increasing evidence suggests that autophagy could induce immune checkpoint proteins (PD-L1, MHC-I/II) degradation of cancer cells, which play an important role in regulating cancer cell immune escape. In addition to autophagic degradation of immune checkpoint proteins, autophagy induction in immune cells (macrophages, dendritic cells) manipulates antigen presentation and T cell activity. These reports suggest that autophagy could negatively or positively regulate cancer cell immune escape by immune checkpoint protein and antigens degradation, cytokines release, antigens generation. These controversial phenomenon of autophagy on cancer cell immune evasion may be derived from different experimental context or models. In addition, autophagy maybe exhibit a role in regulating host excessive immune response. So rational combination with autophagy could enhance the efficacy of cancer immunotherapy. In this review, the current progress of autophagy on cancer immune escape is discussed. Video Abstract.

CD47/SIRPα pathway mediates cancer immune escape and immunotherapy.

The adaptive immune checkpoints such as PD-1(programmed death-1)/PD-L1 (programmed death-ligand 1) play an important role in cancer immunotherapy, whereas increasing evidence suggests that cancer cell evades immune surveillance by innate immune checkpoints such as SIRPα (signal-regulatory protein α)/CD47 (cluster of differentiation 47). In multiple types of cancer cells and solid tumor tissues, highly expressed CD47 protein level has been observed, which is triggered by some transcription factors including NFκB, Myc, and HIF. As a transmembrane protein, the binding of CD47 to SIRPα ligand on phagocytes results in phagocytosis resistance and cancer cell immune escape. In contrast, CD47-SIRPα interaction blockade enhances cancer cell clearance by phagocytes such as macrophages and dendritic cells (DCs) to activate an innate immune response, whereas this process could promote antigen cross-presentation by antigen present cells (APCs) leading to T cell priming, consequently, activates an adaptive antitumor immune response. In this review, we discussed the current SIRPα-CD47 axis-mediated cancer cell immune escape and immunotherapy, which could provide an effective antitumor strategy by the innate and adaptive immune response.

Eosinophilic gastroenteritis with abdominal pain and ascites: A case report.

BACKGROUND: Eosinophilic gastroenteritis (EGE) is a rare disease that presents many unspecific gastroenterological symptoms. The disease includes three types depending on the depth of eosinophil infiltration in the gastrointestinal tract. The serosal type is the most rare, presenting as ascites. CASE SUMMARY: A 34-year-old man presented with abdominal pain, diarrhea without bloody stool, or nausea. Laboratory test results revealed a peripheral blood eosinophil count (4.85 × 109/L), which was remarkedly elevated. Computed tomography scan demonstrated extensive intestinal wall edema thickening in the duodenum, jejunum, ascending colon and transverse colon; multiple exudative effusion surrounding the intestinal tract, and ascites in the abdominal cavity. A series of examinations excluded eosinophil elevation in secondary diseases. Endoscopic multipoint biopsy detected eosinophilic infiltration in the mucous layer of the transverse colon, with ≥ 50 eosinophils/high power field. All symptoms vanished after a few days of steroid therapy and ascites disappeared within 2 wk. CONCLUSION: EGE should be considered in patients with abdominal pain, ascites, and eosinophilia. Multiple point biopsies are essential for diagnosis.

Prevalence of BRCA1/BRCA2 pathogenic variation in Chinese Han population.

BACKGROUND: Pathogenic variation in BRCA1 and BRCA2 (BRCA) is one of the most frequent genetic predispositions for hereditary breast cancer. The identification of the variant carriers plays an important role in prevention and treatment of cancer. Despite a population size of 1.4 billion and a quarter million annual new breast cancer cases, knowledge regarding the prevalence of BRCA variation in the Chinese population remains elusive. METHODS: In this study, we used BRCA-targeted sequencing and bioinformatics approaches to screen for BRCA variants in 11 386 Chinese Han individuals, including 9331 females and 2055 males. RESULTS: We identified 1209 BRCA variants, 34 of which were pathogenic, including 11 in BRCA1 and 23 in BRCA2. These variants were distributed among 43 individuals (37 females and 6 males), with 13 carrying BRCA1 and 30 carrying BRCA2 variants. Based on these data, we determined a prevalence of 0.38%, or 1 carrier of a BRCA pathogenic variant out of every 265 Chinese Han individuals, and 5.1 million carriers among the Chinese Han population of 1.3 billion. CONCLUSION: Our study provides basic knowledge about the prevalence of BRCA pathogenic variation in the Chinese Han population. This information should be valuable for BRCA-related cancer prevention and treatment in the population.

Upregulation of Rab31 is associated with poor prognosis and promotes colorectal carcinoma proliferation via the mTOR/p70S6K/Cyclin D1 signalling pathway.

AIMS: Rab31, a Rab5 subfamily member, has emerged as a modulator of membrane trafficking. Our study serves to clarify the role and mechanism of Rab31 in colorectal carcinoma (CRC) pathogenesis. MATERIALS AND METHODS: The differential expression of Rab31 was examined in paired normal and cancerous colonic tissues by quantitative PCR, western blot and immunochemistry. The prognostic significance of Rab31 was analysed by univariate and multivariate survival analyses. We also investigated the effects of Rab31 on tumour growth in vitro. KEY FINDINGS: We observed that Rab31, which is related to histological differentiation in CRC, was markedly overexpressed in CRC cells. Moreover, patients who showed higher Rab31 levels had a shortened survival period relative to those with low Rab31 levels. Rab31 knockdown significantly downregulated cyclin D1, p-mTOR, and p-p70S6K expression. Moreover, the expression of Rab31-induced p-p70S6K was almost inhibited by rapamycin, a well-established inhibitor of mTOR. Similarly, rapamycin also significantly decreased the stimulatory effect of Rab31 on the expression of cyclin D1. SIGNIFICANCE: These findings suggested that Rab31 enhanced proliferation, promoted cell cycle progression, and inhibited apoptosis of colorectal carcinoma cells through the mTOR pathway.

The Cytoplasmic Expression Of CLDN12 Predicts An Unfavorable Prognosis And Promotes Proliferation And Migration Of Osteosarcoma.

BACKGROUND: To date, the impact and potential molecular mechanisms of CLDN12 and its association with malignancy in osteosarcoma have not been determined. MATERIALS AND METHODS: In the present study, the expression profiles of CLDN12 in osteosarcoma cell lines and tissues were explored by immunohistochemistry. A fetal osteoblast cell line was transfected with a eukaryotic expression plasmid, and endogenous CLDN12 in osteosarcoma cells were silenced through an RNA interference (RNAi) method. These transfections were verified, and the activation state of Thr308 site in protein kinase B (Akt) was explored by Western blotting. Moreover, the malignant phenotype of osteosarcoma cells was evaluated by cell counting kit-8 (CCK-8), colony formation, Transwell, and wound-healing assays. Furthermore, osteoblast cells were treated with the phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002 to determine the impact of the PI3K/Akt signaling pathway on cell migration ability. RESULTS: The results revealed that CLDN12 was overexpressed and localized in the cytoplasm of osteosarcoma cells, and its overexpression was associated with an unfavorable prognosis, irrespective of tumor node metastasis stage. In addition, the knockdown of CLDN12 in cultured osteosarcoma cells markedly attenuated cell proliferation and migration, as indicated by the Cell Counting Kit-8 assay, colony formation assay, scratch wound healing assay and Transwell migration assay. The results also demonstrated that the overexpression of CLDN12 increased the activation of Thr308 site in Akt in fetal osteoblast cells, and the PI3K inhibitor LY294002 partially decreased CLDN12-promoted proliferation and metastasis. CONCLUSION: In conclusion, the results of the present study indicated that CLDN12 promoted cell proliferation and migration through the PI3K/Akt signaling pathway in osteosarcoma cells, suggesting that CLDN12 may be a potential agent in the treatment of patients with osteosarcoma.

High expression of long intergenic non-coding RNA LINC00662 contributes to malignant growth of acute myeloid leukemia cells by upregulating ROCK1 via sponging microRNA-340-5p.

Long non-coding RNAs (lncRNAs) have emerged as crucial regulatory factors in diverse pathological processes, especially in tumorigenesis. Accumulating evidence has demonstrated that long intergenic non-coding RNA 00662 (LINC00662) is overexpressed in multiple cancers and facilitates cancer development and progression. However, whether LINC00662 is involved in acute myeloid leukemia (AML) remains unknown. This study was aimed to explore the expression, biological function and regulatory mechanism of LINC00662 in AML. Here, we found that LINC00662 was significantly increased in AML tissues and cell lines. Knockdown of LINC00662 significantly reduced the growth of AML cells and upregulated AML cell apoptosis. In contrast, overexpression of LINC00662 promoted AML cell growth. MicroRNA-340-5p (miR-340-5p) was predicted as a target of LINC00662. Luciferase reporter assays and RNA pull-down assays confirmed that LINC00662 directly interacted with miR-340-5p. Expression of miR-340-5p was downregulated in AML and silencing of LINC00662 upregulated miR-340-5p expression in AML cells. Moreover, overexpression of miR-340-5p inhibited cell growth and increased apoptosis in AML cells. Inhibition of miR-340-5p significantly reversed the inhibitory effect of LINC00662 silencing on AML cell growth. In addition, Rho-associated protein kinase 1 (ROCK1) was verified as a target gene of miR-340-5p in AML cells. Restoration of ROCK1 expression partially reversed LINC00662 silencing or miR-340-5p overexpression-mediated inhibitory effect on AML cell growth. Overall, our results demonstrate that LINC00662 contributes to the malignant growth of AML cells by upregulating ROCK1 via sponging miR-340-5p, highlighting the important role of the LINC00662/miR-340-5p/ROCK1 axis in regulating the malignant behavior of AML cells.

The Long Noncoding RNA, LINC01555, Promotes Invasion and Metastasis of Colorectal Cancer by Activating the Neuropeptide, Neuromedin U.

BACKGROUND This study aimed to investigate the role of the long noncoding RNA (lncRNA), LINC01555, on the migration and invasion of colorectal cancer (CRC) cells, its expression in CRC tissue, and its interaction with the neuropeptide, neuromedin U (NmU). MATERIAL AND METHODS LINC01555 expression in SW620 and HCT116 CRC cells, and NCM460 normal colorectal cells, and 48 resection specimens containing CRC and adjacent normal tissue, was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cox regression analysis was used to assess the relationship between LINC01555 expression and patient survival. The effects of LINC01555 expression on CRC cell proliferation, migration, and invasion were assessed using the cell counting kit-8 (CCK-8) assay, the colony formation assay, and the transwell assay. Functional studies determined the interaction between LINC01555 and NmU in the development of CRC. RESULTS The Cancer Genome Atlas (TCGA) dataset showed that LINC01555 was highly expressed in CRC tissue when compared with adjacent normal colorectal tissue. LINC01555 expression was positively correlated with tumor stage, but negatively correlated with disease-free survival (DFS) and overall survival (OS) and was an independent risk factor for CRC. The receiver operating characteristic (ROC) curve analysis showed the diagnostic specificity of LINC01555 in CRC. Knockdown of LINC01555 inhibited cell proliferation, migration, and invasion of CRC cells. Functional studies showed that knockdown of NmU reduced cell migration and invasion of CRC cells that overexpressed LINC01555. CONCLUSIONS Increased expression of LINC01555 was found in CRC tissues and promoted the invasion of CRC cells by upregulating the expression of NmU.

Downregulation of ZNF278 arrests the cell cycle and decreases the proliferation of colorectal cancer cells via inhibition of the ERK/MAPK pathway.

Zinc finger protein 278 is a zinc finger transcription factor encoded on the 22q12.2 chromosome. Previous studies revealed that ZNF278 expression was significantly upregulated in colorectal cancer (CRC) tissue compared to adjacent non-tumor tissue. However, the expression and specific roles of ZNF278 in CRC remain unknown. ZNF278 expression was knocked down using specific siRNAs, which was confirmed by western blotting, and the effects of ZNF278 siRNAs on CRC cell proliferation were investigated. In addition, the effects of ZNF278 overexpression were confirmed by western blotting and cell proliferation assay. Correlations between ZNF278 and the ERK/MAPK pathway were also detected by western blotting. We found that ZNF278 knockdown significantly induced cell cycle arrest, resulting in cyclin D1/E1 downregulation and p21 upregulation. Moreover, we demonstrated that downregulation of ZNF278 decreased the proliferation of CRC cells via inhibition of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway for the first time. In conclusion, ZNF278 played a prominent role in the pathogenesis of CRC, and promoted CRC cell proliferation via the ERK/MAPK pathway, suggesting that it may act as a potential target in the diagnosis or treatment of CRC.

High expression of GPR116 indicates poor survival outcome and promotes tumor progression in colorectal carcinoma.

Previous studies have found that G-protein-coupled receptor 116 (GPR116) is a regulator of breast cancer metastasis. However, the role of GPR116 in colorectal carcinoma (CRC) carcinogenesis and progression is unknown. In this study, We found GPR116 expression was significantly up-regulated in CRC specimens compared with corresponding non-cancerous tissues. Increased GPR116 expression in CRC was correlated with histological differentiation and distant metastasis. In addition, high expression of GPR116 was significantly associated with poor overall survival of CRC patients, which was also confirmed by GSE14333, GSE17536 and GSE33113 datasets from the Gene Expression Omnibus (GEO). Furthermore, we demonstrated that the ability of proliferation and invasion of CRC cell lines HCT116 and LOVO was markedly reduced after transfected with siRNA-GPR116. Meanwhile, GPR116 may drive EMT in CRC cells through AKT/EKR signaling pathway, resulting in metastasis. Thus, GPR116 may be a novel reliable prognostic indicator and a risk factor in CRC progression.

The in vitro and vivo anti-tumor effects and molecular mechanisms of suberoylanilide hydroxamic acid (SAHA) and MG132 on the aggressive phenotypes of gastric cancer cells.

Here, we found that both SAHA and MG132 synergistically inhibited proliferation, glycolysis and mitochondrial oxidization, induced cell cycle arrest and apoptosis in MGC-803 and MKN28 cells. SAHA increased cell migration and invasionat a low concentration. SAHA induced the overexpression of acetyl histone 3 and 4, which were recruited to p21, p27, Cyclin D1, c-myc and nanog promoters to transcriptionally up-regulate the former two and down-regulate the latter three. The expression of acetyl-histone 3 and 4 was increased during gastric carcinogenesis and positively correlated with cancer differentiation. SAHA and MG132 exposure suppressed tumor growth by inhibiting proliferation and inducing apoptosis in nude mice, increased serum ALT and AST levels and decreased hemaglobin level, white blood cell and neutrophil numbers. These data indicated that SAHA and MG132 in vivo and vitro synergistically induced cytotoxicity and apoptosis, suppressed proliferation, growth, migration and invasion of gastric cancer cells. Therefore, they might potentially be employed as chemotherapeutic agents if the hepatic injury and the killing effects of peripheral blood cells are avoided or ameliorated.

Unusual Cytotoxic Steroidal Saponins from the Gorgonian Astrogorgia dumbea.

Three steroidal saponins, including astrogorgiosides A (1) and B (2) bearing acetamido-glucose moieties, and astrogorgioside C (3) with a 19-nor and bearing an aromatized B ring steroid aglycone, together with a known major saponin dimorphoside A (4), were obtained from the gorgonian Astrogorgia dumbea collected near Dongshan Island in East China Sea. Structures of these compounds were elucidated by in-depth spectral and chemical methods, including 2D-NMR, HR-ESI-MS spectra, and acidic hydrolysis. For the first time, acetamido-glucose moiety is being reported from a gorgonian. The B-ring aromatized steroid aglycone of compound 3 is also rare in marine natural products. Compounds 1-3 exhibited moderate cytotoxic activity with IC50 values of 26.8-45.6 µM against human tumor cells Bel-7402 and K562.

Bioprospecting potential of halogenases from Arctic marine actinomycetes.

BACKGROUND: Halometabolites, an important group of natural products, generally require halogenases for their biosynthesis. Actinomycetes from the Arctic Ocean have rarely been investigated for halogenases and their gene clusters associated, albeit great potential of halometabolite production has been predicted. Therefore, we initiated this research on the screening of halogenases from Arctic marine actinomycetes isolates to explore their genetic potential of halometabolite biosynthesis. RESULTS: Nine halogenase genes were discovered from sixty Arctic marine actinomycetes using in-house designed or previously reported PCR primers. Four representative genotypes were further cloned to obtain full coding regions through genome walking. The resulting halogenases were predicted to be involved in halogenation of indole groups, antitumor agent ansamitocin-like substrates, or unknown peptide-like compounds. Genome sequencing revealed a potential gene cluster containing the halogenase predicted to catalyze peptide-like compounds. However, the gene cluster was probably silent under the current conditions. CONCLUSIONS: PCR-based screening of halogenase genes is a powerful and efficient tool to conduct bioprospecting of halometabolite-producing actinomycetes from the Arctic. Genome sequencing can also identify cryptic gene clusters potentially producing new halometabolites, which might be easily missed by traditional isolation and chemical characterization. In addition, our study indicates that great genetic potential of new halometabolites can be expected from mostly untapped actinomycetes from the polar regions.

Screening of potential diagnostic markers and therapeutic targets against colorectal cancer.

OBJECTIVE: To identify genes with aberrant promoter methylation for developing novel diagnostic markers and therapeutic targets against primary colorectal cancer (CRC). METHODS: Two paired CRC and adjacent normal tissues were collected from two CRC patients. A Resi: MBD2b protein-sepharose-4B column was used to enrich the methylated DNA fragments. Difference in the average methylation level of each DNA methylation region between the tumor and control samples was determined by log2 fold change (FC) in each patient to screen the differentially methylated DNA regions. Genes with log2FC value ≥4 or ≤-4 were identified to be hypermethylated and hypomethylated, respectively. Then, the underlying functions of methylated genes were speculated by Gene Ontology database and pathway enrichment analyses. Furthermore, a protein-protein interaction network was built using Search Tool for the Retrieval of Interacting Genes/Proteins database, and the transcription factor binding sites were screened via the Encyclopedia of DNA Elements (ENCODE) database. RESULTS: Totally, 2,284 and 1,142 genes were predicted to have aberrant promoter hypermethylation or hypomethylation, respectively. MAP3K5, MAP3K8, MAPK14, and MAPK9 with promoter hypermethylation functioned via MAPK signaling pathway, focal adhesion, or Wnt signaling pathway, whereas MAP2K1, MAPK3, MAPK11, and MAPK7 with promoter hypomethylation functioned via TGF-beta signaling pathway, neurotrophin signaling pathway, and chemokine signaling pathway. CREBBP, PIK3R1, MAPK14, APP, ESR1, MAPK3, and HRAS were the seven hubs in the constructed protein-protein interaction network. RPL22, RPL36, RPLP2, RPS7, and RPS9 were commonly regulated by transcription factors, and YY1 and IRF4 were hypermethylated. CONCLUSION: MAPK14, MAPK3, HRAS, YY1, and IRF4 may be considered as potential biomarkers for early diagnosis and therapy of CRC.

Angiopoietin-like protein 2 negatively regulated by microRNA-25 contributes to the malignant progression of colorectal cancer.

Angiopoietin-like protein 2 (ANGPTL2) is associated with tumor progression while dysregulation of its expression has been observed in various types of cancer. However, the expression and role of ANGPTL2 remain exclusive in colorectal cancer (CRC). In the present study, we determined the expression levels of ANGPTL2 in CRC tissues and cells. The roles of ANGPTL2 and miR-25 in the migration and invasion of CRC SW620 and HCT-116 cells were also investigated using transwell assays or scratch wound assays. The results showed that ANGPTL2 increased with metastatic progression. Increased ANGPTL2 and decreased microRNA-25 (miR-25) expression were found to coexist in CRC. The functional studies revealed that knockdown of ANGPTL2 reduced colony formation, and the invasive and migratory abilities of human CRC SW620 and HCT-116 cells. Similarly, overexpression of miR-25 resulted in reduced colony formation, invasion and migration in both cell lines. The overexpression of miR-25 led to a decreased ANGPTL2 mRNA and protein expression, whereas the downregulation of miR-25 resulted in increased ANGPTL2 mRNA and protein expression, in SW620 and HCT-116 cells. miR-25 directly targeted ANGPTL2 by binding to its 3'­UTR, as determined by the dual luciferase reporter assay. To the best of our know-ledge, the results of this study suggest for the first time that the abnormal upregulation of ANGPTL2 in CRC is associated with miR-25 downregulation. Additionally, miR-25­mediated ANGPTL2 promoted the malignant progression of CRC. The present study provides evidence supporting ANGPTL2 and miR-25 as diagnostic or therapeutic targets for CRC.

Inhibition of mTOR signalling potentiates the effects of trichostatin A in human gastric cancer cell lines by promoting histone acetylation.

Deregulation of the mammalian target of rapamycin pathway (mTOR pathway) is associated with human cancer. The relationship between mTOR pathway and histone acetylation is still unclear in gastric cancer (GC). Immunohistochemistry was used to examine the phosphorylation of mTOR and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) in GC tissues. MKN45 and SGC7901 cells were treated with the mTOR inhibitor rapamycin (RAPA) alone or in combination with the phosphatidylinositol 3-kinase inhibitor LY294002 and the histone deacetylase (HDAC) inhibitor trichostatin A (TSA). Small interfering RNA (siRNA) technology was also used to knockdown mTOR. Phosphorylated mTOR and phosphorylated 4E-BP1 were expressed in 71.1% and 68.4% of the human GC tissues tested, respectively; significantly higher than the levels in para-cancerous tissues (50% and 57.9%) and normal tissues (44.6% and 29%). RAPA markedly inhibited cell proliferation, induced G1 cell cycle arrest, and reduced phosphorylation of p70 S6 protein kinase (p70S6K) and 4E-BP1 in GC cells, particularly when used in combination with LY294002 or TSA. The mRNA expression of the tumour suppressor gene p21(WAF1) increased significantly in GC cells treated with both RAPA and TSA. Histone acetylation also increased after RAPA and TSA treatment or siRNA knockdown of mTOR. Our findings suggest that the mTOR pathway is activated in GC, and also that inhibition of mTOR enhances the ability of TSA to suppress cell proliferation and lead to cell cycle arrest via increasing histone acetylation and p21(WAF1) transcription in human MKN45 and SGC7901 GC cells.

mTOR signaling pathway is a target for the treatment of colorectal cancer.

BACKGROUND: mTOR signaling has been suggested to be an important factor involved in tumorigenesis, but its role in human colorectal cancer (CRC) has not been completely elucidated. Herein, the purpose of this study was to analyze the distribution pattern of mTOR signaling components in CRC and adenoma and to determine whether targeted inhibition of mTOR could be a potential therapeutic strategy for CRC. METHODS: Immunohistochemical analysis was performed on human CRC and adenoma for mTOR signaling components, including mTOR, p70s6 K, and 4EBP1. HCT116 and SW480 human CRC cell lines were treated with siRNA directed against mTOR, and cell viability, cell cycle, and apoptosis were assessed. HCT116 and SW480 cells were injected into athymic nude mice to establish a CRC xenograft model. Mice were randomly transfected with either nontargeting control or mTOR siRNA, and tumor volume, mTOR signaling activity, and apoptosis were evaluated. RESULTS: mTOR signaling components, including mTOR, p70s6 K, and 4EBP1, were highly activated in glandular elements of CRC and colorectal adenomas with high-grade intraepithelial neoplasia (HIN), with a correlation between staining intensity and depth of infiltration in CRC. Inhibition of mTOR expression using a specific mTOR siRNA resulted in considerably decreased in vitro and in vivo cell growth. CONCLUSIONS: mTOR signaling is associated with the clinical pathological parameters of human CRC. siRNA-mediated gene silencing of mTOR may be a novel therapeutic strategy for CRC.