Associations between the Nrf2/Keap1 pathway and mitochondrial functions in colorectal cancer are affected by metastasis

New insights into the role of mitochondrial dynamics in oxidative stress-induced diseases

The accumulation of excess reactive oxygen species (ROS) can lead to oxidative stress (OS), which can induce gene mutations, protein denaturation, and lipid peroxidation directly or indirectly. The expression is reduced ATP level in cells, increased cytoplasmic Ca2+, inflammation, and so on. Consequently, ROS are recognized as significant risk factors for human aging and various diseases, including diabetes, cardiovascular diseases, and neurodegenerative diseases. Mitochondria are involved in the production of ROS through the respiratory chain. Abnormal mitochondrial characteristics, including mitochondrial OS, mitochondrial fission, mitochondrial fusion, and mitophagy, play an important role in various tissues. However, previous excellent reviews focused on OS-induced diseases. In this review, we focus on the latest progress of OS-induced mitochondrial dynamics, discuss OS-induced mitochondrial damage-related diseases, and summarize the OS-induced mitochondrial dynamics-related signaling pathways. Additionally, it elaborates on potential therapeutic methods aimed at preventing oxidative stress from further exacerbating mitochondrial disorders.

Nanomedicine Strategies in Conquering and Utilizing the Cancer Hypoxia Environment

Cancer with a complex pathological process is a major disease to human welfare. Due to the imbalance between oxygen (O2) supply and consumption, hypoxia is a natural characteristic of most solid tumors and an important obstacle for cancer therapy, which is closely related to tumor proliferation, metastasis, and invasion. Various strategies to exploit the feature of tumor hypoxia have been developed in the past decade, which can be used to alleviate tumor hypoxia, or utilize the hypoxia for targeted delivery and diagnostic imaging. The strategies to alleviate tumor hypoxia include delivering O2, in situ O2 generation, reprogramming the tumor vascular system, decreasing O2 consumption, and inhibiting HIF-1 related pathways. On the other side, hypoxia can also be utilized for hypoxia-responsive chemical construction and hypoxia-active prodrug-based strategies. Taking advantage of hypoxia in the tumor region, a number of methods have been applied to identify and keep track of changes in tumor hypoxia. Herein, we thoroughly review the recent progress of nanomedicine strategies in both conquering and utilizing hypoxia to combat cancer and put forward the prospect of emerging nanomaterials for future clinical transformation, which hopes to provide perspectives in nanomaterials design.

Pathophysiological role of BACH transcription factors in digestive system diseases

BTB and CNC homologous (BACH) proteins, including BACH1 and BACH2, are transcription factors that are widely expressed in human tissues. BACH proteins form heterodimers with small musculoaponeurotic fibrosarcoma (MAF) proteins to suppress the transcription of target genes. Furthermore, BACH1 promotes the transcription of target genes. BACH proteins regulate physiological processes, such as the differentiation of B cells and T cells, mitochondrial function, and heme homeostasis as well as pathogenesis related to inflammation, oxidative-stress damage caused by drugs, toxicants, or infections; autoimmunity disorders; and cancer angiogenesis, epithelial-mesenchymal transition, chemotherapy resistance, progression, and metabolism. In this review, we discuss the function of BACH proteins in the digestive system, including the liver, gallbladder, esophagus, stomach, small and large intestines, and pancreas. BACH proteins directly target genes or indirectly regulate downstream molecules to promote or inhibit biological phenomena such as inflammation, tumor angiogenesis, and epithelial-mesenchymal transition. BACH proteins are also regulated by proteins, miRNAs, LncRNAs, labile iron, and positive and negative feedback. Additionally, we summarize a list of regulators targeting these proteins. Our review provides a reference for future studies on targeted drugs in digestive diseases.

Circ_0011385 knockdown inhibits cell proliferation, migration and invasion, whereas promotes cell apoptosis by regulating miR-330-3p/MYO6 axis in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a malignant tumor. Recent studies have showed circular RNA (circRNA) participates in the development of CRC. The study was designed to reveal the role of circ_0011385 in CRC progression and underneath mechanism.

METHODS

The expression circ_0011385, microRNA-330-3p (miR-330-3p) and myosin VI (MYO6) mRNA were determined by quantitative real-time polymerase chain reaction. Protein expression was detected by Western blot assay. Cell proliferation was investigated by 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT), cell colony formation and flow cytometry assays. Cell apoptosis was demonstrated by flow cytometry analysis. Cell migration and invasion were evaluated by wound-healing assay and transwell invasion assay, respectively. The binding sites between miR-330-3p and circ_0011385 or MYO6 were predicted by CircInteractome or starBase online databases, and identified by dual-luciferase reporter and RNA immunoprecipitation assays.

RESULTS

Circ_0011385 and MYO6 expression were dramatically upregulated, while miR-330-3p expression was downregulated in CRC tissues or cells compared with control groups. Circ_0011385 expression was associated with tumor size, tumor-node-metastasis stage (TNM) stage and lymph node metastasis of CRC patients. Circ_0011385 silencing or MYO6 absence repressed cell proliferation, migration and invasion, whereas induced cell apoptosis in CRC. Additionally, miR-330-3p inhibitor or MYO6 overexpression attenuated the repressive impacts of circ_0011385 silencing on CRC process. Circ_0011385 was associated with miR-330-3p, and miR-330-3p targeted MYO6. Circ_0011385 knockdown inactivated MEK1/2/ERK1/2 signaling pathway by miR-330-3p/MYO6 axis. Furthermore, circ_0011385 knockdown suppressed tumor growth in vivo.

CONCLUSION

Circ_0011385 regulated CRC process by miR-330-3p/MYO6 axis through MEK1/2/ERK1/2 signaling pathway, providing a novel therapeutic target for CRC.

Mitochondrial Metabolism Targeted Nanoplatform for Efficient Triple-Negative Breast Cancer Combination Therapy

Tumor reprogram pathway of mitochondrial metabolism is an emerging approach for malignant tumor treatment, such as triple-negative breast cancer. In this study, a tumor/mitochondria cascaded targeting, adenosine-triphosphate (ATP) responsive nanocarrier of zeolitic imidazolate framework-90 (ZIF-90) for breast cancer combination therapy is reported. Atovaquone (AVO) and hemin are loaded into ZIF-90, then a peptide iRGD with tumor-targeting ability is modified on the ZIF-90 nanoplatform. Hemin can specifically degrade BTB and CNC homology1 (BACH1), resulting in the changes of mitochondrial metabolism, and AVO acts as the inhibitor of the electron transport chain (ETC). The degradation of BACH1 using hemin can effectively improve the anti-tumor efficiency of mitochondrial metabolism inhibitor AVO, by increasing dependency on mitochondrial respiration. This nanoplatform displays both tumor-targeting and mitochondria-targeting capacity with high level of ATP responsive drug release behavior. The specific characteristic of mitochondria-targeting ability of this nanoplatform can increase the accumulation of AVO in the mitochondria, and in turn, can effectively improve the inhibition of the ETC. Both in vitro and in vivo results reveal that this composite nanocarrier has excellent tumor inhibition ability with limited side effects. Accordingly, this study provides an attractive strategy in the mitochondrial metabolism for cancer targeted therapy.

Fusobacterium Nucleatum Promotes the Development of Colorectal Cancer by Activating a Cytochrome P450/Epoxyoctadecenoic Acid Axis via TLR4/Keap1/NRF2 Signaling

Emerging research has revealed regulation of colorectal cancer metabolism by bacteria. Fusobacterium nucleatum (Fn) plays a crucial role in the development of colorectal cancer, however, whether Fn infection modifies metabolism in patients with colorectal cancer remains unknown. Here, LC-MS/MS-based lipidomics identified the upregulation of cytochrome P450 monooxygenases, primarily CYP2J2, and their mediated product 12,13-EpOME in patients with colorectal cancer tumors and mouse models, which increased the invasive and migratory ability of colorectal cancer cells in vivo and in vitro by regulating the epithelial-mesenchymal transition (EMT). Metagenomic sequencing indicated a positive correlation between increased levels of fecal Fn and serum 12,13-EpOME in patients with colorectal cancer. High levels of CYP2J2 in tumor tissues also correlated with high Fn levels and worse overall survival in patients with stage III/IV colorectal cancer. Moreover, Fn was found to activate TLR4/AKT signaling, downregulating Keap1 and increasing NRF2 to promote transcription of CYP2J2. Collectively, these data identify that Fn promotes EMT and metastasis in colorectal cancer by activating a TLR4/Keap1/NRF2 axis to increase CYP2J2 and 12,13-EpOME, which could serve as clinical biomarkers and therapeutic targets for Fn-infected patients with colorectal cancer. SIGNIFICANCE: This study uncovers a mechanism by which Fusobacterium nucleatum regulates colorectal cancer metabolism to drive metastasis, suggesting the potential biomarker and therapeutic utility of the CYP2J2/12,13-EpOME axis in Fn-infected patients.

The Nrf2 in the pathophysiology of the intestine: Molecular mechanisms and therapeutic implications for inflammatory bowel diseases

Nrf2 (nuclear factor erythroid 2-related factor 2) is a stress-responsive transcription factor, associated with cellular homeostasis. Under normal conditions Nrf2 is kept in the cytoplasm by Kelch-like ECH-associated protein 1 (Keap1) which facilitates its degradation. Meanwhile, oxidative or electrophilic stress trigger Keap1 dissociation from the Nrf2/Keap1 complex and Nrf2 translocation to the nucleus where it induces the expression of numerous anti-oxidative and anti-inflammatory genes. The Nrf2/Keap1 axis plays a crucial role in the development of gastrointestinal (GI) tract and the maintenance of its proper functionality. This axis also seems to be a promising candidate for prevention of inflammatory bowel diseases (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), as well as their severe complications such as intestinal fibrosis and colorectal cancer. This review focuses on the role of Nrf2/Keap1 in 1) the development and proper functionality of GI tract, 2) the pathophysiology of GI diseases and their long-term complications, 3) the effectiveness of currently used drugs and non-conventional treatments which influence Nrf2/Keap1 and are potentially effective in IBD treatment, as well as 4) the effect of gut microbiota on Nrf2/Keap1 pathway in IBD.

Hsa_circ_0128846 promotes tumorigenesis of colorectal cancer by sponging hsa-miR-1184 and releasing AJUBA and inactivating Hippo/YAP signalling

Hsa_circ_0128846 was found to be the most significantly up-regulated circRNA in our bioinformatics analysis. However, the role of hsa_circ_0128846 in colorectal cancer has not been explored. We thus aim to explore the influence and mechanism of hsa_circ_0128846 in colorectal cancer by sponging its downstream miRNA target miR-1184. We collected 40 colorectal cancer patients' tumour tissues to analyse the expression of hsa_circ_0128846, miR-1184 and AJUBA using qRT-PCR and Western blot where needed. Then, we constructed stably transfected SW480 and HCT116 cells to study the influence of hsa_circ_0128846, miR-1184 and AJUBA on colorectal cancer cell phenotypes. To obtain reliable results, a plethora of experiments including RNA immunoprecipitation assay, flow cytometry, EdU incorporation assay, wound healing migration assay, transwell invasion assay and live imaging of nude mice xenograft assay were performed. The binding relationship between hsa_circ_0128846, miR-1184 and AJUBA mRNA in colorectal cancer was validated by reported gene assay. In colorectal cancer tissues, circ_0128846 and AJUBA were both significantly up-regulated, while miR-1184 was significantly down-regulated compared with healthy tissues. Meanwhile, hsa_circ_0128846 can absorb miR-1184 to promote the progression of CRC in vivo and SW480 and HCT116 cell phenotypes in vitro. The knockdown of AJUBA, a downstream target of miR-1184, reversed the effect of miR-1184 in CRC cells via enhancing the phosphorylation of the Hippo/YAP signalling pathway proteins MST1, LATS1 and YAP. This study revealed that hsa_circ_0128846 contributed to the development of CRC by decreasing the expression of miR-1184, thereby increasing AJUBA expression and inactivating Hippo/YAP signalling.

Whole-exome mutational landscape of metastasis in patient-derived hepatocellular carcinoma cells

In order to explore the genomic basis for liver cancer metastasis, whole-exome sequencing (WES) was performed on patient-derived hepatocellular carcinoma (HCC) cell lines with differential metastatic potentials and analyzed their clonal evolution relationships. An evolutionary tree based on genomic single nucleotide polymorphism (SNP) was constructed in MegaX software. The WES data showed that the average percentage of heterogeneous mutations in each HCC cell lines was 16.55% (range, 15.38%–18.17%). C: G > T: A and T: A > C: G somatic transitions were the two most frequent substitutions. In these metastatic HCC cell lines, non-silent gene mutations were found in 21.88% of known driver genes and 10 classical signaling pathways. The protein interaction network was constructed by STRING, and hub genes were found in the shared trunk mutation genes and the heterogeneous branch mutations respectively. In cBioPortal database, some of the selected hub genes were found to be associated with poor overall survival (OS) of HCC patients. Among the mutated HCC driver genes, a novel KEAP1 mutation with a homozygous frameshift truncation at the c-terminal Nrf2 binding region was detected and verified in MHCC97-H and HCC97LM3 cells. In conclusion, WES data demonstrate that HCC cell lines from tumor biopsy specimens of the same patient have obtained different metastatic potentials through repeated selection in rodents in vivo, and they do indeed have a genetic relationship at the genomic level.