Background Oncolytic viro-immunotherapy holds promise for cancer treatment. While immune activation can be robustly triggered by oncolytic viruses, negative feedback is often upregulated in the tumour microenvironment (TME). Lactate accumulation, signal transducer and activator of transcription 3 (STAT3) activation, indoleamine 2,3-dioxygenase 1 (IDO1) expression, and myeloid-derived suppressor cell (MDSC) infiltration coordinate to shape the immunosuppressive TME. Methods Representative hepatocellular carcinoma (HCC) cell lines and HCC-bearing mice were treated with oncolytic Newcastle disease virus (NDV), alone or in combination with dichloroacetate (DCA, a pyruvate dehydrogenase kinase (PDK) inhibitor). Results We found that infection with oncolytic NDV led to significant induction of the aforementioned suppressive factors. Interestingly, DCA significantly reduced lactate release, STAT3 activation, IDO1 upregulation, and MDSC infiltration in NDV-treated HCC. Consequently, DCA significantly enhanced the antitumour immune responses, leading to improved antitumour efficacy and prolonged survival in mouse models of ascitic and subcutaneous HCC. Furthermore, DCA increased NDV replication in a PDK-1-dependent manner in HCC. Conclusions Targeting aerobic glycolysis by DCA improves NDV-mediated viro-immunotherapy in HCC by mitigating immune negative feedback and promoting viral replication. These findings provide a rationale for targeting reprogrammed metabolism together with oncolytic virus-mediated viro-immunotherapy for HCC treatment.
Background 3-Hydroxybutyrate dehydrogenase type 2 (BDH2) is known to catalyse a rate-limiting step in the biogenesis of the mammalian siderophore and regulate intracellular iron metabolism. Here we aim to explore the expression and possible function of BDH2 in nasopharyngeal carcinoma (NPC). Methods The transcription and protein expression of BDH2 in NPC were determined by both real-time RT-PCR and immunohistochemistry staining assays. Cell proliferation, migration and invasion were evaluated by MTT assay, wound-healing assay and Transwell assay, respectively. The profile of genes regulated by restoring BDH2 expression in NPC cells was analysed by cDNA microarray. The level of iron in NPC cells was detected by iron colorimetric assay. Results The expression of BDH2 was significantly downregulated in NPC. Ectopic expression of BDH2 inhibited NPC cell proliferation and colony formation. Meanwhile, BDH2 suppressed the migration and invasion of NPC cells by reversing the epithelial-mesenchymal transition (EMT). In addition, a higher level of BDH2 decreased the growth and metastasis of NPC cells via reducing intracellular iron level. Conclusions Our findings suggest that BDH2 may be a candidate tumour-suppressor gene in NPC. Decreasing intracellular iron could be an effective therapeutic approach for NPC.
In recent years, a large number of studies have been carried out in the field of immune metabolism, highlighting the role of metabolic energy reprogramming in altering the function of immune cells. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells generated during a large array of pathological conditions, such as cancer, inflammation, and infection, and show remarkable ability to suppress T-cell responses. These cells can also change their metabolic pathways in response to various pathogen-derived or inflammatory signals. In this review, we focus on the roles of glucose, fatty acid (FA), and amino acid (AA) metabolism in the differentiation and function of MDSCs in the tumour microenvironment, highlighting their potential as targets to inhibit tumour growth and enhance tumour immune surveillance by the host. We further highlight the remaining gaps in knowledge concerning the mechanisms determining the plasticity of MDSCs in different environments and their specific responses in the tumour environment. Therefore, this review should motivate further research in the field of metabolomics to identify the metabolic pathways driving the enhancement of MDSCs in order to effectively target their ability to promote tumour development and progression.
Background Ferroptosis is an iron-dependent, lipid peroxide-mediated cell death that may be exploited to selective elimination of damaged and malignant cells. Recent studies have identified that small-molecule erastin specifically inhibits transmembrane cystine-glutamate antiporter system x(c)(-), prevents extracellular cystine import and ultimately causes ferroptosis in certain cancer cells. In this study, we aimed to investigate the molecular mechanism underlying erastin-induced ferroptosis resistance in ovarian cancer cells. Methods We treated ovarian cancer cells with erastin and examined cell viability, cellular ROS and metabolites of the transsulfuration pathway. We also depleted cystathionine beta-synthase (CBS) and NRF2 to investigate the CBS and NRF2 dependency in erastin-resistant cells. Results We found that prolonged erastin treatment induced ferroptosis resistance. Upon exposure to erastin, cells gradually adapted to cystine deprivation via sustained activation of the reverse transsulfuration pathway, allowing the cells to bypass erastin insult. CBS, the biosynthetic enzyme for cysteine, was constantly upregulated and was critical for the resistance. Knockdown of CBS by RNAi in erastin-resistant cells caused ferroptotic cell death, while CBS overexpression conferred ferroptosis resistance. We determined that the antioxidant transcriptional factor, NRF2 was constitutively activated in erastin-resistant cells and NRF2 transcriptionally upregulated CBS. Genetically repression of NRF2 enhanced ferroptosis susceptibility. Conclusions Based on these results, we concluded that constitutive activation of NRF2/CBS signalling confers erastin-induced ferroptosis resistance. This study demonstrates a new mechanism underlying ferroptosis resistance, and has implications for the therapeutic response to erastin-induced ferroptosis.
Background Mitochondrial dynamics plays an important role in tumour progression. However, how these dynamics integrate tumour metabolism in hepatocellular carcinoma (HCC) metastasis is still unclear. Methods The mitochondrial fusion protein mitofusin-1 (MFN1) expression and its prognostic value are detected in HCC. The effects and underlying mechanisms of MFN1 on HCC metastasis and metabolic reprogramming are analysed both in vitro and in vivo. Results Mitochondrial dynamics, represented by constant fission and fusion, are found to be associated with HCC metastasis. High metastatic HCC displays excessive mitochondrial fission. Among genes involved in mitochondrial dynamics, MFN1 is identified as a leading downregulated candidate that is closely associated with HCC metastasis and poor prognosis. While promoting mitochondrial fusion, MFN1 inhibits cell proliferation, invasion and migration capacity both in vitro and in vivo. Mechanistically, disruption of mitochondrial dynamics by depletion of MFN1 triggers the epithelial-to-mesenchymal transition (EMT) of HCC. Moreover, MFN1 modulates HCC metastasis by metabolic shift from aerobic glycolysis to oxidative phosphorylation. Treatment with glycolytic inhibitor 2-Deoxy-d-glucose (2-DG) significantly suppresses the effects induced by depletion of MFN1. Conclusions Our results reveal a critical involvement of mitochondrial dynamics in HCC metastasis via modulating glucose metabolic reprogramming. MFN1 may serve as a novel potential therapeutic target for HCC.
Background Chemoresistance remains a critical event that accounts for colorectal cancer (CRC) lethality. The aim of this study is to explore the ability of dichloroacetate (DCA) to increase chemosensitivity in CRC and the molecular mechanisms involved. Methods The effects of combination treatment of DCA and oxaliplatin (L-OHP) were analysed both in vitro and in vivo. The DCA-responsive proteins in AMPK pathway were enriched using proteomic profiling technology. The effect of DCA on CAB39-AMPK signal pathway was analysed. In addition, miRNA expression profiles after DCA treatment were determined. The DCA-responsive miRNAs that target CAB39 were assayed. Alterations of CAB39 and miR-107 expression were performed both in vitro and on xenograft models to identify miR-107 that targets CAB39-AMPK-mTOR signalling pathway. Results DCA increased L-OHP chemosensitivity both in vivo and in vitro. DCA could upregulate CAB39 expression, which activates the AMPK/mTOR signalling pathway. CAB39 was confirmed to be a direct target of miR-107 regulated by DCA. Alterations of miR-107 expression were correlated with chemoresistance development in CRC both in vitro and in vivo. Conclusion These findings suggest that the miR-107 induces chemoresistance through CAB39-AMPK-mTOR pathway in CRC cells, thus providing a promising target for overcoming chemoresistance in CRC.
Background About 25-37% of resectable pancreatic ductal adenocarcinoma (PDAC) had a great chance of early recurrence after radical resection, which is mainly due to preoperative micrometastasis. We herein demonstrated the profiles of ctDNA in resectable PDAC and use of ctDNA to identify patients with potential micrometastasis. Methods A total of 113 and 44 resectable PDACs were enrolled in discovery and validation cohorts, separately. A panel containing 50 genes was used to screen ctDNA by an NGS-based assessment with high specificity. Results In the discovery cohort, the overall detection rate was 38.05% (43/113). Among positive ctDNA, KRAS mutation had the highest detection rate (23.01%, 26/113), while the others were <5%. Survival analysis showed that plasma KRAS mutations, especially KRAS G12D mutation, had significant association with OS and RFS of resectable PDAC. Plasma KRAS G12D mutation showed a strong correlation with early distant metastasis. In the validation cohort, survival analysis showed similar association between plasma KRAS G12D mutation and poor outcomes. Conclusions This study demonstrated that plasma KRAS mutations, especially KRAS G12D mutation, served as a useful predictive biomarker for prognosis of resectable PDAC. More importantly, due to high correlation with micrometastasis, preoperative detection of plasma KRAS G12D mutation helps in optimising surgical selection of resectable PDAC.
Background We previously demonstrated that the pleomorphic adenoma gene like-2 (PLAGL2) is involved in the pathogenesis of Hirschsprung disease. Enhanced PLAGL2 expression was observed in several malignant tumours. However, the exact function of PLAGL2 and its underlying mechanism in colorectal cancer (CRC) remain largely unknown. Methods Immunohistochemical analysis of PLAGL2 was performed. A series of in vitro and in vivo experiments were conducted to reveal the role of PLAGL2 in the progression of CRC. Results Enhanced PLAGL2 expression was significantly associated with EMT-related proteins in CRC. The data revealed that PLAGL2 promotes CRC cell proliferation, migration, invasion and EMT both in vitro and in vivo. Mechanistically, PLAGL2 promoted the expression of ZEB1. PLAGL2 enhanced the expression and nuclear translocation of beta-catenin by decreasing its phosphorylation. The depletion of beta-catenin neutralised the regulation of ZEB1 that was caused by enhanced PLAGL2 expression. The small-molecule inhibitor PNU-74654, also impaired the enhancement of ZEB1 that resulted from the modified PLAGL2 expression. The depletion of ZEB1 could block the biological function of PLAGL2 in CRC cells. Conclusions Collectively, our findings suggest that PLAGL2 mediates EMT to promote colorectal cancer metastasis via beta-catenin-dependent regulation of ZEB1.
Background The histone demethylase LSD1 is a key mediator driving tumorigenesis, which holds potential as a promising therapeutic target. However, treatment with LSD1 inhibitors alone failed to result in complete cancer regression. Methods The synergistic effects of TCP (a LSD1 inhibitor) and GSK-J1 (a JMJD3 inhibitor) against HNSCC were determined in vitro and in preclinical animal models. Genes modulated by chemical agents or siRNAs in HNSCC cells were identified by RNA-seq and further functionally interrogated by bioinformatics approach. Integrative siRNA-mediated gene knockdown, rescue experiment and ChIP-qPCR assays were utilised to characterise the mediators underlying the therapeutic effects conferred by TCP and GSK-J1. Results Treatment with TCP and GSK-J1 impaired cell proliferation, induced apoptosis and senescence in vitro, which were largely recapitulated by simultaneous LSD1 and JMJD3 knockdown. Combinational treatment inhibited tumour growth and progression in vivo. Differentially expressed genes modulated by TCP and GSK-J1 were significantly enriched in cell proliferation, apoptosis and cancer-related pathways. SPP1 was identified as the mediator of synergy underlying the pro-apoptosis effects conferred by TCP and GSK-J1. Co-upregulation of LSD1 and JMJD3 associated with worse prognosis in patients with HNSCC. Conclusions Our findings revealed a novel therapeutic strategy of simultaneous LSD1 and JMJD3 inhibition against HNSCC.
BACKGROUND: Preoperative prediction of lymph node (LN) status is integral to determining the most appropriate treatment strategy for colorectal cancer (CRC). This study aimed to develop and validate a nomogram to predict LN metastasis in CRC preoperatively. METHODS: A total of 530 patients were enrolled and divided into training and validation cohorts. The tumour stroma percentage (TSP) of the preoperative biopsies was assessed. The risk factors for LN metastasis were selected, and a nomogram was constructed subsequently. The performance of the nomogram was assessed by using the AUROC and the calibration curve, and then validated in the validation cohort. RESULTS: High TSP was significantly associated with LN metastasis in both the training and validation cohorts. Computed tomography (CT)-reported T stage, CT-reported LN status, preoperative tumour differentiation, carcinoembryonic antigen, carbohydrate antigen 19-9 and TSP were independent predictors of LN metastasis in CRC. A nomogram incorporating the six predictors was constructed. The nomogram yielded good discrimination and calibration, with an AUROC of 0.846 (95% CI: 0.807 -0.886) and 0.809 (95% CI: 0.745-0.872) in the training and validation cohorts, respectively. CONCLUSIONS: Assessment of TSP in the preoperative biopsies provided additional information about the LN status. The nomogram was useful for tailored therapy in CRC preoperatively.
Background Cancer poses a huge disease burden, which could be reduced by adopting healthy lifestyles mainly composed of healthy diet, body weight, physical activity, limited alcohol consumption, and avoidance of smoking. However, no systematic review has summarised the relations of combined lifestyle factors with cancer morbidity and mortality. Methods EMBASE and PubMed were searched up to April 2019. Cohort studies investigating the association of combined lifestyle factors with risks of incident cancer and cancer mortality were selected. Summary hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using random-effects models. Heterogeneity and publication bias tests were conducted. Results The HRs (95% CIs) comparing individuals with the healthiest versus the least healthy lifestyles were 0.71 (0.66-0.76; 16 studies with 1.9 million participants) for incident cancer and 0.48 (0.42-0.54; 30 studies with 1.8 million participants) for cancer mortality. Adopting the healthiest lifestyles was also associated with 17 to 58% lower risks of bladder, breast, colon, endometrial, oesophageal, kidney, liver, lung, rectal, and gastric cancer. The relations were largely consistent and significant among participants with different characteristics in the subgroup analyses. Conclusions Adopting healthy lifestyles is associated with substantial risk reduction in cancer morbidity and mortality, and thus should be given priority for cancer prevention.
Background Dyskeratosis congenita 1 (DKC1) is dysregulated in several cancers. However, the expression and function of DKC1 in colorectal cancer (CRC) is rarely reported. Methods Tissue microarrays (TAMs) including 411 cases of CRC tissues and corresponding paracancerous tissues were used to examine the DKC1 expression. The correlations between the DKC1 expression and clinicopathological or survival characters were further analysed. The functions and molecular mechanism of DKC1 in CRC were investigated through a series of in vitro and in vivo experiments. Results The result showed that DKC1 expression was increased in CRC tissues. Increased DKC1 expression was associated with high grade of TNM stage, additional lymph node metastasis, and poor prognosis of patients with CRC. Multivariate COX analysis indicated that DKC1 can act as an independent prognostic factor for patients with CRC. DKC1 also facilitated the CRC angiogenesis and metastasis by increasing HIF-1 alpha and VEGF expression levels. Chromatin immunoprecipitation assay demonstrated that DKC1 facilitated HIF-1 alpha expression by regulating HIF-1 alpha promoter activity. Conclusion DKC1 appears to regulate CRC angiogenesis and metastasis through directly activating HIF-1 alpha transcription. DKC1 can serve as an accurate indicator in predicting the prognosis of patients with CRC and act as a potential therapeutic target for CRC.
Background Recent studies have shown that multidrug resistance may be induced by the high stemness of cancer cells. Following prolonged chemotherapy, MDR protein 1 (MDR1) and CD133 increase in CRC, but the relationship between them is unclear. Methods The relationship between MDR and CSC properties in CRC was determined via CCK-8 assay, apoptosis assay, DOX uptake and retention, immunohistochemistry, immunofluorescence and flow cytometry. The correlations between their expression levels were evaluated using Spearman's rank statistical test and the Mann-Whitney test. Furthermore, the effect of CD133 on the repression of the AKT/NF-kappa B/MDR1 signalling pathway was investigated in vitro and in vivo. Results We found that CD133 increased with the emergence of drug-resistance phenotypes, and the high expression of MDR1/P-gp was consistently accompanied by positive expression of CD133 as demonstrated by the analysis of patient samples. Up- or downregulation of CD133 could regulate MDR via AKT/NF-kappa B/MDR1 signalling in CRC. A rescue experiment showed that the AKT/NF-kappa B signalling pathway is the main mechanism by which CD133 regulates MDR1/P-gp expression in CRC. Conclusions Taken together, our results suggest that targeting CD133 reverses drug resistance via the AKT/NF-kappa B/MDR1 pathway and that this pathway might serve as a potential therapeutic target to reverse MDR in CRC.
Background Intratumoural CD103(+)CD8(+) T cells have been linked to prolonged survival in several malignancies. However, the clinical significance of CD103(+)CD8(+) T cells in gastric cancer remains unexplored. Methods Gastric cancer tissues from Zhongshan Hospital and data from Gene Expression Omnibus were obtained and analysed. Immunohistochemistry and flow cytometry were performed to detect the number and phenotypical characteristics of CD103(+)CD8(+) T cells. The effect of programmed cell death protein-1 (PD-1) blockade on CD103(+)CD8(+) T cells was evaluated with the use of an in vitro study based on fresh tumour tissues. Results CD103(+)CD8(+) T cells predicted superior overall survival and provided better prognostic power than total CD8(+) T cells in gastric cancer. Patients with high CD103(+)CD8(+) T cell infiltration also gained more benefit from adjuvant chemotherapy. Flow cytometry analysis showed that CD103(+)CD8(+) T cells exerted superior anti-tumour effects with stronger retention capacity and cytotoxicity. Moreover, an in vitro study showed that CD103(+)CD8(+) T cells were more functionally restored after PD-1 blockade than CD103(-)CD8(+) T cells. Conclusions CD103(+)CD8(+) T cells might be a useful marker to predict prognosis and therapeutic efficacy for gastric cancer patients. Efforts to increase intratumoural CD103(+)CD8(+) T cell frequency might be a novel therapeutic strategy in gastric cancer.
Background The small GTPase Ran is upregulated in multiple cancers and fundamental for cancer cell survival and progression, but its significance and molecular mechanisms in colorectal cancer (CRC) remain elusive. Methods Ran expression was detected in CRC cell lines and tumour tissues. In vitro and in vivo functional assays were performed to examine the effects of Ran on cell proliferation and metastasis. The pathways and effectors regulated by Ran were explored by an unbiased screening. Bioinformatics prediction and experimental validation were used to identify the miRNA regulator for Ran. Results Ran expression was frequently increased in metastatic CRC cells and tissues, especially in metastatic tissues. The upregulation of Ran correlated with poor CRC patient prognosis. Ran silencing reduced proliferation and metastasis of CRC cells both in vitro and in vivo. Ran regulated the expression of EGFR and activation of ERK and AKT signalling pathways. miR-802 was identified as an upstream regulator of Ran and miR-802 overexpression resulted in antiproliferative and antimetastatic activities. Conclusion Our study demonstrates the oncogenic roles and underlying mechanisms of Ran in CRC and the novel miR-802/Ran/EGFR regulatory axis may provide potential biomarkers for the treatment of CRC.