The pathogenesis of gut microbiota in humans can be indicated due to the wide application of techniques, such as 16S rRNA sequencing. Presently, several studies have found a significant difference in ...fecal flora between normal individuals and patients with gastric cancer. Although clinical research on the feedback mechanism of gastric flora and gut microbiota is lacking, clarifying the relationship between gut microbiota and the characteristics of cancer is significant for the early diagnosis of gastric cancer. This study was conducted to review the results of several studies in the past 5 years and analyze the intestinal bacteria in patients with gastric cancer and compare them with those in patients with esophageal and small intestine cancers. It was found that the gut microbiota in patients with gastric cancer was similar to that in patients with esophageal cancer. However, making an analysis and comparing the gut microbiota in patients with small intestine and gastric cancers was impossible due to the low incidence of small intestinal cancer. Our review summarized the research progress on using the gut microbiota for early screening for gastric cancer, and the results of this study will provide a further direction in this field.
Key points
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We reviewed several relative mechanisms of the gut microbiota related to gastric cancer.
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The gut microbiota in gastric, esophageal, and small intestine cancers are significantly different in types and quantity, and we have provided some tips for further research.
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A prospective review of sequencing methods and study results on the gut microbiota in gastric, esophageal, and small intestine cancers was described.
Metastasis is a complex pathophysiological process. As the main cause of cancer mortality in humans it represents a serious challenge to both basic researchers and clinicians. Here we report the ...design and construction of a multi-organ microfluidic chip that closely mimics the in vivo microenvironment of lung cancer metastasis. This multi-organs-on-a-chip includes an upstream “lung” and three downstream “distant organs”, with three polydimethylsiloxane (PDMS) layers and two thin PDMS microporous membranes bonded to form three parallel microchannels. Bronchial epithelial, lung cancer, microvascular endothelial, mononuclear, and fibroblast cells were grown separated by the biomembrane in upstream “lung”, while astrocytes, osteocytes, and hepatocytes were grown in distant chambers, to mimic lung cancer cell metastasis to the brain, bone, and liver. After culture in this system, lung cancer cells formed a “tumor mass”, showed epithelial-mesenchymal transition (with altered expression of E-cadherin, N-cadherin, Snail1, and Snail2) and invasive capacity. A549 cells co-cultured with astrocytes overexpressed CXCR4 protein, indicating damage of astrocytes after cancer cell metastasis to the brain. Osteocytes overexpressed RANKL protein indicates damage of osteocytes after cancer cell metastasis to the bone, and hepatocytes overexpressed AFP protein indicates damage to hepatocytes after cancer cell metastasis to the liver. Finally, in vivo imaging of cancer growth and metastasis in a nude mice model validated the performance of metastasis in the organs-on-chip system. This system provides a useful tool to mimic the in vivo microenvironment of cancer metastasis and to investigate cell–cell interactions during metastasis.
Gut microbiota have been implicated in the development of cancer. Colorectal and gastric cancers, the major gastrointestinal tract cancers, are closely connected with the gut microbiome. ...Nevertheless, the characteristics of gut microbiota composition that correlate with gastric cancer are unclear. In this study, we investigated gut microbiota alterations during the progression of gastric cancer to identify the most relevant taxa associated with gastric cancer and evaluated the potential of the microbiome as an indicator for the diagnosis of gastric cancer. Compared with the healthy group, gut microbiota composition and diversity shifted in patients with gastric cancer. Different bacteria were used to design a random forest model, which provided an area under the curve value of 0.91. Verification samples achieved a true positive rate of 0.83 in gastric cancer. Principal component analysis showed that gastritis shares some microbiome characteristics of gastric cancer. Chemotherapy reduced the elevated bacteria levels in gastric cancer by more than half. More importantly, we found that the genera
Lactobacillus
and
Megasphaera
were associated with gastric cancer.
Key Points
• Gut microbiota has high sensitivity and specificity in distinguishing patients with gastric cancer from healthy individuals, indicating that gut microbiota is a potential noninvasive tool for the diagnosis of gastric cancer.
• Gastritis shares some microbiota features with gastric cancer, and chemotherapy reduces the microbial abundance and diversity in gastric cancer patients.
• Two bacterial taxa, namely, Lactobacillus and Megasphaera, are predictive markers for gastric cancer.
Monoclonal antibodies （mAbs） blocking immune checkpoint molecules, especially programmed cell death l （PD-1） and its ligands programmed cell death 1 ligand 1 （PD-L1） and ligand 2 （PD-L2）, are ...currently been in- vestigated for treatment of various tumors 1-3. PD-L1 and PD-L2 are usually upregulated on the surface of mul- tiple tumor cells to mediate immune tolerance through the interaction with inhibitory PD-1 molecule 4.
Metastasis is responsible for the death of most breast cancer patients. Robo1 has been implicated as a tumor suppressor for various cancers including breast cancer. However, it is not well understood ...how Robo1 expression is regulated during tumorigenesis. In this study, we uncovered that the transmembrane proline rich γ-carboxyglutamic acid protein 4 (PRRG4) promotes breast cancer metastasis by downregulating Robo1. Analysis of mRNA expression data in The Cancer Genome Atlas and immunohistochemistry assay on breast tumor samples showed that PRRG4 expression was higher in breast tumors than in normal breast tissues. Experiments with PRRG4 knockdown and overexpression revealed that PRRG4 promoted migration and invasion of breast cancer cells, and enhanced metastasis in an experimental metastasis model. Mechanistically, we found that PRRG4 via its LPSY and PPPY motifs recruited the E3 ubiquitin ligase NEDD4, which induced ubiquitination and degradation of Robo1, thus contributing to migration and invasion of breast cancer cells. In addition, PRRG4 interacted with and enhanced protein tyrosine kinase Src and FAK activation. Overall, our data support a model that PRRG4 via NEDD4 downregulates the Robo1, resulting in the activation of Src and FAK and promoting breast cancer metastasis. PRRG4 may be a novel target for treating metastatic breast cancer.
Non-small cell lung cancer (NSCLC) accounts for approximately 85% of clinical lung cancer cases. MicroRNA-93 (miR-93) is an oncomiR in many types of human cancer, exerting pivotal effects in the ...development and progression of malignancies, including NSCLC. However, the mechanism underlying miR-93 involvement in NSCLC is unknown. Our purpose was to reveal and explain this mechanism, with the goal of contributing to the development of new diagnostic biomarkers and individualized therapeutic tools.
The expression of miR-93 was determined in NSCLC cell lines A549, H1975, and H1299. The cells were transfected with control plasmids (Mock group), miR-93 overexpression plasmids (miR-93 Up group), or miR-93 inhibitor plasmids (miR-93 Down group) to generate stable miR-93-overexpressing or -depleted cells. The effects of miR-93 on proliferation, migration, and invasion of these cells were determined. The
effects of miR-93 on tumor metastasis were determined in an NSCLC xenograft mouse model. The molecular mechanisms underlying these effects were investigated via dual luciferase reporter assay and western blotting.
MiR-93 expression levels were significantly greater in the NSCLC cell lines than in normal lung epithelial cells. Cell proliferation, migration, and invasion were significantly stimulated by miR-93 upregulation (all
<0.05) and inhibited by miR-93 downregulation. Dual luciferase reporter assay demonstrated that miR-93 directly bound with the 3'-untranslated region of the tumor suppressor gene
. Western blotting analysis indicated that miR-93 activated the PI3K/Akt pathway by inhibiting LKB1, PTEN, and p21. Increased expression of miR-93 induced significant hepatic metastasis of lung cancer in the xenograft mouse model.
Overexpression of miR-93 facilitates tumorigenesis and metastasis of NSCLC. These findings provide novel insight into the mechanism of miR-93 involvement in NSCLC, suggesting that miR-93 may serve as a potential therapeutic target.
Around the world, cervical cancer is the fourth most common cancer among women. MicroRNAs (miRNAs) and agents that target mRNAs have been introduced as novel diagnostic markers and therapeutic ...approaches, respectively, in cancer. MiRNA-486-5p is a candidate regulator of phosphatase and tensin homolog (PTEN) in silico, and the downregulation of PTEN in cervical cancer is not consistent with its mutation, which suggests that PTEN may be subjected to post-transcription modification moderated by miRNAs. Here, we aimed to explore whether miR-486-5p is a regulator in the development of cervical cancer through the PI3K/Akt pathway by targeting PTEN.
The expression level of miR-486-5p in human cervical cancer serum and tissues were analyzed through quantitative RT-PCR. Human cervical cancer cell lines HeLa and SiHa were selected to explore the effects of miR-486-5p downregulated or overexpression on cell proliferation, migration, and invasion, respectively. Moreover, we observed the effect of miR-486-5p downregulated on tumorigenesis using HeLa cell in vivo. Besides, the relationship between miR-486-5p and PTEN were determined by dual luciferase reporter gene assay.
Compared to control subjects, miR-486-5p was significantly overexpressed in cervical cancer patients' serum and tissues. Suppression of miR-486-5p expression significantly inhibited HeLa cell proliferation, colony formation, migration, and invasion, as well as tumor growth in nude mice, while miR-486-5p overexpression stimulated SiHa cell proliferation, colony formation, migration, and invasion. We also confirmed that miR-486-5p directly targeted the 3'-untranslated region of the tumor-suppressor gene PTEN, inhibiting its expression, and that overexpression of miR-486-5p activated the PI3K/Akt pathway.
We conclude that miR-486-5p stimulates cell proliferation, migration, and invasion through inhibition of PTEN expression and activation of the oncogenic PI3K/Akt pathway in cervical cancer. Our findings implicate serum miR-486-5p as a novel molecular biomarker that may provide effective approaches to both diagnosis and treatment in cervical cancer.
Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer type with poor prognosis due to its high metastatic potential, however, the role of metabolic reprogramming in the metastasis of PDAC ...cell is not known. Here, we report that COX6B2 drive metastasis but not cancer cell proliferation in PDAC by enhancing oxidative phosphorylation function (OXPHOS). Transcriptome and clinical analyses revealed that cytochrome c oxidase subunit 6B2 (COX6B2) positively associated with metastasis of PDAC cells. Knockdown of COX6B2 in PDAC cells tuned down the assembly of complex IV and downregulated the function of OXPHOS, whereas re-expression of COX6B2 restored the function of OXPHOS and metastatic potential. Mechanistically, COX6B2 upregulated OXPHOS function to active purinergic receptor pathway for the metastasis of PDAC cells. Notably, the metastatic potential in PDAC could be reversely regulated by metformin, a drug was found accelerating the degradation of COX6B2 mRNA in this study. Collectively, our findings indicated that a complex metabolic control mechanism might be involved in achieving the balance of metabolic requirements for both growth and metastasis in PDAC, and regulation of the expression of COX6B2 could potentially encompass one of the targets.
HSP60 is a mitochondrial localized quality control protein responsible for maintaining mitochondrial function. Although HSP60 is considered both a tumor suppressor and promoter in different types of ...cancer, the role of HSP60 in human pancreatic ductal adenocarcinoma (PDAC) remains unknown. In this study, we demonstrated that HSP60 was aberrantly expressed in human pancreatic cancer tissues and cell lines. Analysis of the Cancer Genome Atlas database revealed that HSP60 expression is positively correlated with pancreatic cancer. Further, knockdown of HSP60 attenuated pancreatic ductal cancer cell proliferation and migration/invasion, whereas ectopic expression of HSP60 increased tumorigenesis. Using an in vivo tumorigenicity assay, we confirmed that HSP60 promoted the growth of pancreatic ductal cancer cells. Functional analyses demonstrated that HSP60 plays a key role in the regulation of mitochondrial function. Mechanistically, both HSP60 knockdown and oxidative phosphorylation (OXPHOS) inhibition by metformin decreased Erk1/2 phosphorylation and induced apoptosis and cell cycle arrest, whereas Erk1/2 reactivation with EGF promoted cell proliferation. Intriguingly, in vitro ATP supplementation partially restored Erk1/2 phosphorylation and promoted proliferation in PDAC cells with HSP60 knockdown and OXPHOS inhibition. These results suggest that mitochondrial ATP is an important sensor of Erk1/2 regulated apoptosis and the cell cycle in PDAC cells. Thus, our findings indicate for the first time that HSP60 may serve as a novel diagnostic target of human pancreatic cancer, and that inhibition of mitochondrial function using drugs such as metformin may be a beneficial therapeutic strategy targeting pancreatic cancer cells with aberrant function of the HSP60/OXPHOS/Erk1/2 phosphorylation axis.
TOM70 is a member of the TOM complex that transports cytosolic proteins into mitochondria. Here, we identified two compound heterozygous variants in TOMM70 c.794C>T (p.T265M) and c.1745C>T (p.A582V) ...from a patient with severe anemia, lactic acidosis, and developmental delay. Patient-derived immortalized lymphocytes showed decreased TOM70 expression, oligomerized TOM70 complex, and TOM 20/22/40 complex compared with expression in control lymphocytes. Functional analysis revealed that patient-derived cells exhibited multi-oxidative phosphorylation system (OXPHOS) complex defects, with complex IV being primarily affected. As a result, patient-derived cells grew slower in galactose medium and generated less ATP and more extracellular lactic acid than did control cells. In vitro cell model compensatory experiments confirmed the pathogenicity of TOMM70 variants since only wild-type TOM70, but not mutant TOM70, could restore the complex IV defect and TOM70 expression in TOM70 knockdown U2OS cells. Altogether, we report the first case of mitochondrial disease-causing mutations in TOMM70 and demonstrate that TOM70 is essential for multi-OXPHOS assembly. Mutational screening of TOMM70 should be employed to identify mitochondrial disease-causing gene mutations in the future.
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