Objectives: Clinical observations have demonstrated that copper levels elevate in several cancer types, and copper deprivation is shown to inhibit tumour angiogenesis and growth in both animal models and preclinical trials. However, the content of copper in pancreatic duct adenocarcinoma (PDAC) and whether it is a potential therapy target is still unknown.
Materials and Methods:The levels of copper in PDAC specimens were detected by ICP-MS assays. Copper depletion in Panc-1 or MiaPaCa-2 cells was conducted via copper transporter 1 (SLC31A1) interference and copper chelator tetrathiomolybdate (TM) treatment. The effects of copper deprivation on cancer cells were evaluated by cell proliferation, migration, invasion, colony formation and cell apoptosis.The mechanism of copper deprivation-caused cancer cell quiescence was resolved through mitochondrial dysfunction tests and autophagy studies. The tumour-suppression experiments under the condition of copper block and/or autophagy inhibition were performed both in vitro and in xenografted mice.Results: SLC31A1-dependent copper levels are correlated with the malignant degree of pancreatic cancer. Blocking copper absorption could inhibit pancreatic cancer progression but did not increase cell death. We found that copper deprivation increased mitochondrial ROS level and decreased ATP level, which rendered cancer cells in a dormant state. Strikingly, copper deprivation caused an increase in autophagy to resist death of pancreatic cancer cells. Simultaneous treatment with TM and autophagy inhibitor CQ increased cell death of cancer cells in vitro and retarded cancer growth in vivo.
Conclusions:These findings reveal that copper deprivation-caused cell dormancy and the increase in autophagy is a reason for the poor clinical outcome obtained from copper depletion therapies for cancers. Therefore, the combination of autophagy inhibition and copper depletion is potentially a novel strategy for the treatment of pancreatic cancer and other copper-dependent malignant tumours.
Here, we report a convenient and efficient miRNA inhibition strategy employing the CRISPR system. Using specifically designed gRNAs, miRNA gene has been cut at a single site by Cas9, resulting in knockdown of the miRNA in murine cells. Using a modified CRISPR interference system (CRISPRi), inactive Cas9 can reversibly prevent the expression of both monocistronic miRNAs and polycistronic miRNA clusters. Furthermore, CRISPR/CRISPRi is also capable of suppressing genes in porcine cells.
Angiopoietin-like proteins (ANGPTLs) are a group of eight proteins that share structural similarity to the members of the angiopoietin protein family. ANGPTL3 plays a vital role in the regulation of the plasma levels of triglyceride and cholesterol, mainly via reversible inhibition of the lipoprotein lipase activity. ANGPTL4, which functions as a homo-oligomer different from ANGPTL3 and ANGPTL8, not only regulates the plasma levels of triglyceride and prevents the uptake of dietary lipids into adipose tissues but also inhibits intravascular lipolysis. ANGPTL8 (also called betatrophin) has been identified as an important factor in regulating the triglyceride levels and adipose tissue mass as well as in replenishing the adipose tissue triglyceride store. ANGPTL8 acts together with ANGPTL3 to regulate the lipid metabolism, and ANGPTL8 promotes cleavage of ANGPTL3 to augment the activity of ANGPTL3. In addition, ANGPTL8 promotes proliferation of pancreatic β-cells and enhances insulin secretion. The properties of ANGPTLs in regulating the lipid metabolism suggest their application in the target therapy for metabolic syndrome. As ANGPTLs are regulated by several factors and may be involved in certain specific pathways of lipid metabolism, designing drugs that target ANGPTLs or factors regulating ANGPTLs may be an efficient approach to treat metabolic syndrome.
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