Background
Acquired resistance of 5-fluorouracil (5-FU) remains a clinical challenge in colorectal cancer (CRC), and efforts to develop targeted agents to reduce resistance have not yielded success. Metabolic reprogramming is a key cancer hallmark and confers several tumor phenotypes including chemoresistance. Glucose metabolic reprogramming events of 5-FU resistance in CRC has not been evaluated, and whether abnormal glucose metabolism could impart 5-FU resistance in CRC is also poorly defined.
Methods
Three separate acquired 5-FU resistance CRC cell line models were generated, and glucose metabolism was assessed by measuring glucose and lactate utilization, RNA and protein expressions of glucose metabolism-related enzymes and changes of intermediate metabolites of glucose metabolite pool. The protein levels of hypoxia inducible factor 1α (HIF-1α) in primary tumors and circulating tumor cells of CRC patients were detected by immunohistochemistry and immunofluorescence. Stable HIF1A knockdown in cell models was established with a lentiviral system. The influence of both HIF1A gene knockdown and pharmacological inhibition on 5-FU resistance in CRC was evaluated in cell models in vivo and in vitro.
Results
The abnormality of glucose metabolism in 5-FU-resistant CRC were described in detail. The enhanced glycolysis and pentose phosphate pathway in CRC were associated with increased HIF-1α expression. HIF-1α-induced glucose metabolic reprogramming imparted 5-FU resistance in CRC. HIF-1α showed enhanced expression in 5-FU-resistant CRC cell lines and clinical specimens, and increased HIF-1α levels were associated with failure of fluorouracil analog-based chemotherapy in CRC patients and poor survival. Upregulation of HIF-1α in 5-FU-resistant CRC occurred through non-oxygen-dependent mechanisms of reactive oxygen species-mediated activation of PI3K/Akt signaling and aberrant activation of β-catenin in the nucleus. Both HIF-1α gene knock-down and pharmacological inhibition restored the sensitivity of CRC to 5-FU.
Conclusions
HIF-1α is a potential biomarker for 5-FU-resistant CRC, and targeting HIF-1a in combination with 5-FU may represent an effective therapeutic strategy in 5-FU-resistant CRC.
Endovascular intervention represents the first-line treatment for hemorrhage from pseudoaneurysms after pancreatic surgery. Endovascular embolization or stent-graft placement should be selected individually depending on the involved artery and its vascular anatomy.
Background
Transplant vasculopathy is a major cause of chronic rejection of transplanted organs. In the present study, we examined the effects of CX-5461, a novel selective inhibitor of RNA polymerase I, on development of transplant vasculopathy using a modified model of rat aortic transplantation.
Methods
The thoracic aortas from Fischer rats were transplanted into the abdominal cavity of Lewis rats. CX-5461 was mixed in pluronic gel and administered via perivascular release.
Results
Treatment with CX-5461 mitigated the development of neointimal hyperplasia and vascular inflammation. This effect was likely to be attributable in part to inhibition of macrophage-dependent innate immunity reactions. Specifically, CX-5461 exhibited potent inhibitory effects on macrophage migration and lipopolysaccharide-induced activation. Treatment with CX-5461 also prevented macrophage differentiation and maturation from primary bone marrow cells. In macrophages, CX-5461 did not alter the total amount of p53 protein, but significantly increased p53 phosphorylation, which was involved in regulating cytokine-stimulated macrophage proliferation.
Conclusions
In conclusion, our results suggest that pharmacological inhibition of RNA polymerase I may be a novel strategy to treat transplantation-induced arterial remodeling.
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