Mutation and expression analysis of the IDH1, IDH2, DNMT3A, and MYD88 genes in colorectal cancer

A novel immunogenic cell death signature for the prediction of prognosis and therapies in glioma

Glioma is a primary cranial malignancy with high recurrence rate, poor prognosis and high mortality. However, the roles of immunogenic cell death (ICD) in glioma remain unclear. Twenty ICD genes were analyzed to be differentially expressed between glioma tissues and non-tumor tissues in 371 glioma patients from The Cancer Genome Atlas (TCGA). Patients were classified into three subgroups via unsupervised clustering. Interestingly, the features of cell-infiltrating from three clusters were matched with three immune phenotypes. An applied scoring system was built depending on the expression of hub ICD-related genes. Notably, the ICD-related score was linked with immune checkpoints and the prognosis of glioma patients. In addition, the applied risk model could be used for the prediction of the effect of chemotherapy and immunotherapy for glioma patients. Furthermore, MYD88 was identified to play key roles in the risk model for glioma patients. MYD88 was specifically expressed in malignant cells and validated to correlate with cell proliferation and invasion. Ligand-receptor pairs are determined as novel communications indicating between immunocytes and malignant cells. Therefore, our research established an ICD-related score to investigate the potential effect to chemotherapy and immunotherapy for glioma patients and indicated that MYD88 was a key role in this risk model.

IDH2, a novel target of OGT, facilitates glucose uptake and cellular bioenergy production via NF-κB signaling to promote colorectal cancer progression

BACKGROUND

Although isocitrate dehydrogenase 2 (IDH2) mutations have been the hotspots in recent anticancer studies, the impact of wild-type IDH2 on cancer cell growth and metabolic alterations is still elusive.

METHODS

IDH2 expression in CRC tissues was evaluated by immunohistochemistry, and the correlation between the expression level and the patient's survival rate was analyzed. Cell functional assays included CCK8 and colony formation for cell proliferation in vitro and ectopic xenograft as in vivo experimental model for tumor progression. A targeted metabolomic procedure was performed by liquid chromatography/tandem mass spectrometry to profile the metabolites from glycolysis and tricarboxylic acid (TCA) cycle. Mitochondrial function was assessed by measuring cellular oxygen consumption (OCR) and mitochondrial membrane potential (ΔΨ). Confocal microscope analysis and Western blotting were applied to detect the expression of GLUT1 and NF-κB signaling. O-GlcNAcylation and the interaction of IDH2 with OGT were confirmed by co-immunoprecipitation, followed by Western blotting analysis.

RESULTS

IDH2 protein was highly expressed in CRC tissues, and correlated with poor survival of CRC patients. Wild-type IDH2 promoted CRC cell growth in vitro and tumor progression in xenograft mice. Overexpression of wild-type IDH2 significantly increased glycolysis and TCA cycle metabolites, the ratios of NADH/NAD⁺ and ATP/ADP, OCR and mitochondrial membrane potential (ΔΨ) in CRC cells. Furthermore, α-KG activated NF-κB signaling to promote glucose uptake by upregulating GLUT1. Interesting, O-GlcNAcylation enhanced the protein half-time of IDH2 by inhibiting ubiquitin-mediated proteasome degradation. The O-GlcNAc transferase (OGT)-IDH2 axis promoted CRC progression.

CONCLUSION

Wild-type IDH2 reprogrammed glucose metabolism and bioenergetic production via the NF-κB signaling pathway to promote CRC development and progression. O-GlcNAcylation of IDH2 elevated the stability of IDH2 protein. And the axis of OGT-IDH2 played an essential promotive role in tumor progression, suggesting a novel potential therapeutic strategy in CRC treatment.

DNMT3A R882H mutation drives daunorubicin resistance in acute myeloid leukemia via regulating NRF2/NQO1 pathway

BACKGROUND

DNA methyltransferase 3A (DNMT3A) often mutate on arginine 882 (DNMT3A^R882) in acute myeloid leukemia (AML). AML patients with DNMT3A R882 mutation are usually resistant to daunorubicin treatment; however, the associated mechanism is still unclear. Therefore, it is urgent to investigate daunorubicin resistance in AML patients with DNMT3A R882 mutant.

METHOD

AML cell lines with DNMT3A-wild type (DNMT3A-WT), and DNMT3A-Arg882His (DNMT3A-R882H) mutation were constructed to investigate the role of DNMT3A R882H mutation on cell proliferation, apoptosis and cells' sensitivity to Danunorubin. Bioinformatics was used to analyze the role of nuclear factor-E2-related factor (NRF2) in AML patients with DNMT3A R882 mutation. The regulatory mechanism of DNMT3A R882H mutation on NRF2 was studied by Bisulfite Sequencing and CO-IP. NRF2 inhibitor Brusatol (Bru) was used to explore the role of NRF2 in  AML cells carried DNMT3A R882H mutation.

RESULTS

AML cells with a DNMT3A R882H mutation showed high proliferative and anti-apoptotic activities. In addition, mutant cells were less sensitive to daunorubicin and had a higher NRF2 expression compared with those in WT cells. Furthermore, the NRF2/NQO1 pathway was activated in mutant cells in response to daunorubicin treatment. DNMT3A R882H mutation regulated the expression of NRF2 via influencing protein stability rather than decreasing methylation of NRF2 promoter. Also, NRF2/NQO1 pathway inhibition improved mutant cells' sensitivity to daunorubicin significantly.

CONCLUSION

Our findings identified NRF2 as an important player in the regulation of cell apoptosis through which helps mediate chemoresistance to daunorubicin in AML cells with DNMT3A R882H mutation. Targeting NRF2 might be a novel therapeutic approach to treat AML patients with a DNMT3A R882H mutation. Video abstract.

Aberrant expression of MYD88 via RNA-controlling CNOT4 and EXOSC3 in colonic mucosa impacts generation of colonic cancer

In 2020, the worldwide incidence and mortality of colorectal cancer (CRC) were third and second, respectively. As the 5‐y survival rate is low when CRC is diagnosed at an advanced stage, a reliable method to predict CRC susceptibility is important for preventing the onset and development and improving the prognosis of CRC. Therefore, we focused on the normal colonic mucosa to investigate changes in gene expression that may induce subsequent genetic alterations that induce malignant transformation. Comprehensive gene expression profiling in the normal mucosa adjacent to colon cancer (CC) compared with tissue from non‐colon cancer patients was performed. PCR arrays and qRT‐PCR revealed that the expression of 5 genes involved in the immune response, including MYD88, was increased in the normal mucosa of CC patients. The expression levels of MYD88 were strikingly increased in precancerous normal mucosa specimens, which harbored no somatic mutations, as shown by immunohistochemistry. Microarray analysis identified 2 novel RNA‐controlling molecules, EXOSC3 and CNOT4, that were significantly upregulated in the normal mucosa of CC patients and were clearly visualized in the nuclei. Forced expression of EXOSC3 and CNOT4 in human colonic epithelial cells increased the expression of IFNGR1, MYD88, NFκBIA, and STAT3 and activated ERK1/2 and JNK in 293T cells. Taken together, these results suggested that, in the inflamed mucosa, EXOSC3‐ and CNOT4‐mediated RNA stabilization, including that of MYD88, may trigger the development of cancer and can serve as a potential predictive marker and innovative treatment to control cancer development.

Bioinformatics Analysis Identifies Key Genes and Pathways in Acute Myeloid Leukemia Associated with DNMT3A Mutation

Background

DNA methyltransferase 3 alpha (DNMT3A) mutation was one of the most frequent genetic alterations in acute myeloid leukemia (AML), which was associated with poor prognosis and appeared to be a potential biomarker. Herein, we aimed to identify the key genes and pathways involved in adult AML with DNMT3A mutations and to find possible therapeutic targets for improving treatment.

Methods

The RNA sequencing datasets of 170 adult AML patients were obtained from The Cancer Genome Atlas (TCGA) database. EdgeR of the R platform was used to identify the differentially expressed genes (DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed by Metascape and DAVID. And protein-protein interaction (PPI) network and clustering modules were analyzed with the STRING database and Cytoscape software.

Results

Mutated DNMT3A resulted in a shorter overall survival (OS) in AML patients and obviously associated with age, blast percentage in peripheral blood, and FLT3 mutation. A total of 283 DEGs were detected, of which 95 were upregulated and 188 were downregulated. GO term analysis showed that DEGs were significantly enriched in neutrophil degranulation, myeloid cell differentiation, stem cell proliferation, positive regulation of neurological system process, leukocyte migration, and tissue morphogenesis. KEGG pathway enrichment analysis indicated that the pathway of cancer, PI3K-Akt signaling pathway, and transcriptional misregulation in cancer may play a crucial role in DNMT3A mutation AML. Seven hub genes (BMP4, MPO, THBS1, APP, ELANE, HOXA7, and VWF) had a significant prognostic value.

Conclusion

Bioinformatics analysis in the present study provided novel targets for early diagnosis and new strategies for treatment for AML with DNMT3A mutation.

Early-onset colorectal cancer: A distinct entity with unique genetic features

The aim of the present study was to elucidate the genetic features of early-onset colorectal cancer (CRC), particularly the genetic mutations that may be regarded as prognostic and/or predictive markers in CRC and other malignancies. In total, 40 patients with non-polyposis CRC aged 35 or younger were selected. The formalin-fixed, paraffin-embedded tumors acquired were subjected to mismatch repair (MMR) protein immunochemical staining and gene analysis with next-generation sequencing (44 exons, 17 genes; Ion Torrent Sequencing Platform). A total of 11 (27.5%) tumors presented with MMR protein deficiency (dMMR) and 26 (65%) tumors harbored one or more genetic mutations, including K-RAS proto-oncogene (35%), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA; 20%), B-Raf proto-oncogene (5%), erb-b2 receptor tyrosine kinase 2 (5%), discoidin domain receptor tyrosine kinase 2 (5%), N-RAS proto-oncogene (2.5%), KIT proto-oncogene (2.5%), TSC complex subunit 1 (2.5%), DNA methyltransferase 3 alpha (2.5%) and ABL proto-oncogene 1 (2.5%). Of the dMMR tumors, 81.8% (9/11) of cases presented with mutations in the tested genes, while only 58.6% (17/29) of the MMR-proficient (pMMR) tumors presented with these (P=0.158). PI3KCA was frequently mutated in dMMR tumors compared to pMMR tumors (P=0.025). In a subgroup with a family history of CRC, the dMMR status (P<0.001) and PIK3CA genetic mutation status (P=0.01) were more frequently observed compared to the other two groups (with a family history of other cancer types or no malignancy). Almost all patients who had relatives with CRC presented with both dMMR and other genetic mutations, while this was not observed in the patients who had relatives with other types of carcinoma. Certain genetic mutations that are rarely reported in CRC were only identified in those patients with a family history of carcinoma. In conclusion, non-polyposis CRC in young adults presents as a distinct entity with a unique set of genetic features. However, investigation of more cases in further studies is required to verify the present results.

SIRT2-dependent IDH1 deacetylation inhibits colorectal cancer and liver metastases

Protein lysine acetylation affects colorectal cancer (CRC) distant metastasis through multiple pathways. In a previous proteomics screen, we found that isocitrate dehydrogenase 1 (IDH1) is hyperacetylated in CRC primary tumors and liver metastases. Here, we further investigate the function of IDH1 hyperacetylation at lysine 224 in CRC progression. We find that IDH1 K224 deacetylation promotes its enzymatic activity and the production of α-KG, and we identify sirtuin-2 (SIRT2) as a major deacetylase for IDH1. SIRT2 overexpression significantly inhibits CRC cell proliferation, migration, and invasion. IDH1 acetylation is modulated in response to intracellular metabolite concentration and regulates cellular redox hemostasis. Moreover, IDH1 acetylation reversely regulates HIF1α-dependent SRC transcription which in turn controls CRC progression. Physiologically, our data indicate that IDH1 deacetylation represses CRC cell invasion and migration in vitro and in vivo, while the hyperacetylation of IDH1 on K224 is significantly correlated to distant metastasis and poor survival of colorectal cancer patients. In summary, our study uncovers a novel mechanism through which SIRT2-dependent IDH1 deacetylation regulates cellular metabolism and inhibits liver metastasis of colorectal cancer.

The Role of TLRs in Anti-cancer Immunity and Tumor Rejection

In recent years, a lot of scientific interest has focused on cancer immunotherapy. Although chronic inflammation has been described as one of the hallmarks of cancer, acute inflammation can actually trigger the immune system to fight diseases, including cancer. Toll-like receptor (TLR) ligands have long been used as adjuvants for traditional vaccines and it seems they may also play a role enhancing efficiency of tumor immunotherapy. The aim of this perspective is to discuss the effects of TLR stimulation in cancer, expression of various TLRs in different types of tumors, and finally the role of TLRs in anti-cancer immunity and tumor rejection.

A six-gene prognostic model predicts overall survival in bladder cancer patients

Background

The fatality and recurrence rates of bladder cancer (BC) have progressively increased. DNA methylation is an influential regulator associated with gene transcription in the pathogenesis of BC. We describe a comprehensive epigenetic study performed to analyse DNA methylation-driven genes in BC.

Methods

Data related to DNA methylation, the gene transcriptome and survival in BC were downloaded from The Cancer Genome Atlas (TCGA). MethylMix was used to detect BC-specific hyper-/hypo-methylated genes. Metascape was used to carry out gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. A least absolute shrinkage and selection operator (LASSO)-penalized Cox regression was conducted to identify the characteristic dimension decrease and distinguish prognosis-related methylation-driven genes. Subsequently, we developed a six-gene risk evaluation model and a novel prognosis-related nomogram to predict overall survival (OS). A survival analysis was carried out to explore the individual prognostic significance of the six genes.

Results

In total, 167 methylation-driven genes were identified. Based on the LASSO Cox regression, six genes, i.e., ARHGDIB, LINC00526, IDH2, ARL14, GSTM2, and LURAP1, were selected for the development of a risk evaluation model. The Kaplan–Meier curve indicated that patients in the low-risk group had considerably better OS (P = 1.679e−05). The area under the curve (AUC) of this model was 0.698 at 3 years of OS. The verification performed in subgroups demonstrated the validity of the model. Then, we designed an OS-associated nomogram that included the risk score and clinical factors. The concordance index of the nomogram was 0.694. The methylation levels of IDH2 and ARL14 were appreciably related to the survival results. In addition, the methylation and gene expression-matched survival analysis revealed that ARHGDIB and ARL14 could be used as independent prognostic indicators. Among the six genes, 6 methylation sites in ARHGDIB, 3 in GSTM2, 1 in ARL14, 2 in LINC00526 and 2 in LURAP1 were meaningfully associated with BC prognosis. In addition, several abnormal methylated sites were identified as linked to gene expression.

Conclusion

We discovered differential methylation in BC patients with better and worse survival and provided a risk evaluation model by merging six gene markers with clinical characteristics.

The CIMP-high phenotype is associated with energy metabolism alterations in colon adenocarcinoma

BACKGROUND

CpG island methylator phenotype (CIMP) is found in 15-20% of malignant colorectal tumors and is characterized by strong CpG hypermethylation over the genome. The molecular mechanisms of this phenomenon are not still fully understood. The development of CIMP is followed by global gene expression alterations and metabolic changes. In particular, CIMP-low colon adenocarcinoma (COAD), predominantly corresponded to consensus molecular subtype 3 (CMS3, "Metabolic") subgroup according to COAD molecular classification, is associated with elevated expression of genes participating in metabolic pathways.

METHODS

We performed bioinformatics analysis of RNA-Seq data from The Cancer Genome Atlas (TCGA) project for CIMP-high and non-CIMP COAD samples with DESeq2, clusterProfiler, and topGO R packages. Obtained results were validated on a set of fourteen COAD samples with matched morphologically normal tissues using quantitative PCR (qPCR).

RESULTS

Upregulation of multiple genes involved in glycolysis and related processes (ENO2, PFKP, HK3, PKM, ENO1, HK2, PGAM1, GAPDH, ALDOA, GPI, TPI1, and HK1) was revealed in CIMP-high tumors compared to non-CIMP ones. Most remarkably, the expression of the PKLR gene, encoding for pyruvate kinase participating in gluconeogenesis, was decreased approximately 20-fold. Up to 8-fold decrease in the expression of OGDHL gene involved in tricarboxylic acid (TCA) cycle was observed in CIMP-high tumors. Using qPCR, we confirmed the increase (4-fold) in the ENO2 expression and decrease (2-fold) in the OGDHL mRNA level on a set of COAD samples.

CONCLUSIONS

We demonstrated the association between CIMP-high status and the energy metabolism changes at the transcriptomic level in colorectal adenocarcinoma against the background of immune pathway activation. Differential methylation of at least nine CpG sites in OGDHL promoter region as well as decreased OGDHL mRNA level can potentially serve as an additional biomarker of the CIMP-high status in COAD.

Isocitrate dehydrogenase gene mutations and 2-hydroxyglutarate accumulation in esophageal squamous cell carcinoma

Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are key metabolic enzymes that convert isocitrate to α-ketoglutarate. Somatic point mutations in IDH1/2 confer a gain-of-function in cancer cells, resulting in overproduction of an oncometabolite, 2-hydroxyglutarate (2HG). 2HG interferes with cellular metabolism and epigenetic regulation, contributing to oncogenesis. Given that IDH1 and IDH2 are attracting attention as promising therapeutic targets, better evaluation of the incidence of IDH1 and IDH2 mutations and 2HG level in human cancers is clinically important. This is the first study to assess their incidence in esophageal squamous cell carcinomas (ESCCs). First, we established pyrosequencing assays for IDH1 and IDH2 mutations and revealed that these mutations were absent in 10 ESCC cell lines and 96 ESCC tissues. Second, utilizing IDH1 and IDH2 overexpression vectors, we demonstrated that LC-MS/MS assays can accurately evaluate 2HG level and found that some ESCC cases presented a high level of 2HG. In conclusion, IDH1 or IDH2 mutations play a limited role in the development of ESCC. 2HG is potentially synthesized to high levels in the absence of IDH1 and IDH2 mutations, and this may correlate with progression of ESCCs.

Deleting MyD88 signaling in myeloid cells promotes development of adenocarcinomas of the colon

Intestinal myeloid cells are not only essential for keeping local homeostasis, but also play an important role in regulating the occurrence of colitis and colitis-associated cancer (CAC). In these diseases, the manner in which the myeloid cells work and which molecular pathways influence them are still not fully understood. In our study, we discovered that MyD88 signaling in colonic myeloid cells participates in the development of CAC. Myeloid MyD88-deficient mice showed greater susceptibility to azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CAC, as evidenced by the increase in the number and sizes of tumors. Myeloid MyD88 deletion markedly increased production of pro-inflammatory and pro-tumor cytokines; recruitment of more IL-1β producing-neutrophils in colon from bone marrow; increased in epithelial cell apoptosis and decreased in epithelial cell proliferation; enhancement of colon mucosal expression of COX-2, p-STAT3, β-catenin, and cyclinD1; induction of further DNA damage and β-catenin mutation. To sum up, these results suggest that myeloid MyD88 signaling protects the intestine from tumorigenesis during the development of CAC.

Dual functional roles of the MyD88 signaling in colorectal cancer development

The myeloid differentiation factor 88 (MyD88), an adaptor protein in regulation of the innate immunity, functions to regulate immune responses against viral and bacterial infections in the human body. Toll-like receptors (TLRs) and interleukin 1 receptors (IL-1R) can recognize microbes or endogenous ligands and then recruit MyD88 to activate the MyD88-dependent pathway, while MyD88 mutation associated with lymphoma development and altered MyD88 signaling also involved in cancer-associated cell intrinsic and extrinsic inflammation progression and carcinogenesis. Detection of MyD88 expression was to predict prognosis of various human cancers, e.g., lymphoid, liver, and colorectal cancers. In human cancers, MyD88 protein acts as a bridge between the inflammatory signaling from the TLR/IL-1R and Ras oncogenic signaling pathway. However, the MyD88 signaling played dual functional roles in colorectal cancer, i.e., the tumor-promoting role that enhances cancer inflammation and intestinal flora imbalance to induce tumor invasion and tumor cell self-renewal, and the anti-tumor role that helps to maintain the host-microbiota homeostasis to induce tumor cell cycle arrest and immune responses against cancer cells. This review precisely discusses the up to date literature for these contrasting effects of MyD88 signaling on colorectal cancer development and progression.

Butyrate Inhibits Indices of Colorectal Carcinogenesis via Enhancing α-Ketoglutarate-Dependent DNA Demethylation of Mismatch Repair Genes

SCOPE

Butyrate, the fermentation end product of gut microbiota in the colon, is known for its antitumor effects, but the mechanisms remained to be defined. α-ketoglutarate (α-KG) mediates DNA demethylation and aberrant epigenetic modifications are associated with carcinogenesis. The objectives of this study are to evaluate the effects of butyrate on α-KG mediated epigenetic modification in colorectal adenocarcinoma HT-29 and Caco-2 cells.

METHODS AND RESULTS

Butyrate suppressed proliferation, potentiated differentiation, and induced apoptosis in both HT-29 and Caco-2 cells, associated with enhanced expression of isocitrate dehydrogenase 1 (IDH1) and pyruvate dehydrogenase. Furthermore, butyrate upregulated acetyl-CoA and α-KG, concomitant with enhanced histone acetylation and DNA demethylation in the promoter of DNA mismatch repair (MMR) gene. Knocking down IDH1 abolished the positive effects of butyrate on CRC apoptosis and MMR protein expression, in conjunction with reduced α-KG content. Importantly, α-KG supplementation recovered the beneficial effects of butyrate in IDH1-deficient cells.

CONCLUSION

In summary, butyrate inhibits indices of colorectal carcinogenesis in an α-KG-dependent manner.

Mitochondrial DNA variants in colorectal carcinogenesis: Drivers or passengers?

INTRODUCTION

Mitochondrial DNA alterations have widely been reported in many age-related degenerative diseases and tumors, including colorectal cancer. In the past few years, the discovery of inter-genomic crosstalk between nucleus and mitochondria has reinforced the role of mitochondrial DNA variants in perturbing this essential signaling pathway and thus indirectly targeting nuclear genes involved in tumorigenic and invasive phenotype.

FINDINGS

Mitochondrial dysfunction is currently considered a crucial hallmark of carcinogenesis as well as a promising target for anticancer therapy. Mitochondrial DNA alterations include point mutations, deletions, inversions, and copy number variations, but numerous studies investigating their pathogenic role in cancer have provided inconsistent evidence. Furthermore, the biological impact of mitochondrial DNA variants may vary tremendously, depending on the proportion of mutant DNA molecules carried by the neoplastic cells (heteroplasmy).

CONCLUSIONS

In this review, we discuss the role of different type of mitochondrial DNA alterations in colorectal carcinogenesis and, in particular, we revisit the issue of whether they may be considered as causative driver or simply genuine passenger events. The advent of high-throughput techniques as well as the development of genetic and pharmaceutical interventions for the treatment of mitochondrial dysfunction in colorectal cancer are also explored.

IDH mutations associated impact on related cancer epidemiology and subsequent effect toward HIF-1α

Particular mutations in the isocitrate dehydrogenase gene (IDH) were discovered in several gliomas citing astrocytoma, oligodendroglioma, and glioblastoma multiform, but also in leukemia; these mutations were discovered in nearly all cases of secondary glioblastomas, they evolve from lower-grade gliomas, but are limited in primary high-grade glioblastoma multiform. These mutations distinctively produce (D)-2-hydroxyglutarate (D-2-HG) from alpha-ketoglutarate (α-KG). (D)-2-hydroxyglutarate is accumulated to very high concentrations which inhibit the function of enzymes that are dependent on alpha-ketoglutarate. This modification leads to a hyper-methylated state of DNA and histones, resulting in different gene expression that can activate oncogenes and inactivate tumor-suppressor genes. In our work we review the impact of the mutations that occur in IDH genes, we focus on their impact on distribution in cancer. As IDH mutations appear in many different conditions we expose the extent of IDH mutations and derivate their impact on cancer prognosis, diagnosis, and even their oncogenicity, we will also link their impact to HIF-1α and derivate some target and finally, we present some of the therapeutics under research and out on market.

Myeloid differentiation primary response gene 88-leukotriene B4 receptor 2 cascade mediates lipopolysaccharide-potentiated invasiveness of breast cancer cells

Inflammation and local inflammatory mediators are inextricably linked to tumor progression through complex pathways in the tumor microenvironment. Lipopolysaccharide (LPS) exposure to tumor cells has been suggested to promote tumor invasiveness and metastasis. However, the detailed signaling mechanism involved has not been elucidated. In this study, we showed that LPS upregulated the expression of leukotriene B₄ receptor-2 (BLT2) and the synthesis of BLT2 ligands in MDA-MB-231 and MDA-MB-435 breast cancer cells, thereby promoting invasiveness. BLT2 depletion with siRNA clearly attenuated LPS-induced invasiveness. In addition, we demonstrated that myeloid differentiation primary response gene 88 (MyD88) lies upstream of BLT2 in LPS-potentiated invasiveness and that this ‘MyD88-BLT2’ cascade mediates activation of NF-κB and the synthesis of IL-6 and IL-8, which are critical for the invasiveness and aggression of breast cancer cells. LPS-driven metastasis of MDA-MB-231 cells was also markedly suppressed by the inhibition of BLT2. Together, our results demonstrate, for the first time, that LPS potentiates the invasiveness and metastasis of breast cancer cells via a ‘MyD88-BLT2’-linked signaling cascade.

Metformin prevents DMH-induced colorectal cancer in diabetic rats by reversing the warburg effect

Epidemiologic studies have shown that the treatment of diabetics with metformin reduced the risk of cancer-related mortality. Here, we investigated the chemopreventive effects of metformin on dimethylhydrazine (DMH)-induced colorectal carcinogenesis in diabetic SD rats following metformin treatment and the effect on Warburg effect involved in this process. Diabetic rat models were induced with high-fat feeding in combination with a low dose of Streptozotocin (STZ) and then induce colorectal cancer with a low dose of DMH. The formation of colorectal Aberrant crypt foci (ACF) and the incidence, number and size of the tumor were measured. The proliferation indices of colonic tissues were determined through Proliferating cell nuclear antigen (PCNA) immunostaining. Then detect the expression of PK and IDH in colonic tissues using immunohistochemistry and Western blot. The enzyme activities of HK and PDH in colonic tissues were measured. The growth and expression of PK and IDH and activity of HK and PDH in cell lines LoVo and HT-29 were measured after metformin treatment. The results showed that metformin treatment significantly inhibited the formation of ACF and tumors. The proliferation index of colonic tissues was significantly decreased following metformin treatment. In addition, metformin inhibited cell growth and decreased the imbalance in the expression of the enzymes involved in glycolysis and the TCA cycle. These findings suggested that metformin might produce a synergistic colon cancer-preventative effect in diabetic patients through the regulation of the enzymes expression involved in glucose metabolism.