Detection And Regulation Of Cancer-related RNA Based On Au NP/MnO₂ Nanosheet Probes

Cancer is a worldwide intractable disease alongside"acquired immune deficiency syndrome(AIDS)",which brings suffering to countless patients and their families.Cancer is a disease caused by the canceration of its own cells.Different from viral and bacterial diseases,cancer is not caused by the invasion of external species.It is this endogenous that makes the treatment of cancer face great challenges.For example,although chemotherapy can kill cancer cells,it can also accidentally injure normal cells such as hair follicle cells and digestive tract epithelial cells,which greatly damages the patient's body and causes the patient's physique to decline;surgical treatment is more effective for early cancer patients,but the postoperative metastasis rate for middle and late stage patients is relatively high;radiotherapy has requirements for the location and size of the tumor and destroys normal tissues,which has many limitations.Although there are many problems,people's exploration to overcome cancer has never stopped.Cancer is essentially a gene mutation disease,which is the theoretical foundation for the clinical application of gene therapy.The number of mutated genes in cancer is up to thousands,but the number of key genes that promote its occurrence and development is not much.Regulation of major cancer genes is the foothold of gene therapy,such as Novartis'ceritinib,which acts on the key gene of cancer-ALK gene.With the development of scientific research,people gradually realize the importance of RNA in cancer gene therapy.Micro RNA(mi RNA)is involved in the regulation of a variety of important cancer-related genes,and m RNA is the template for coding proteins.Therefore,the detection and regulation of mi RNA and m RNA is of great significance for exploring new and more effective methods of cancer inhibition.Here,we prepared transportable and regulatory nucleic acid probes based on Mn O₂nanosheets(Mn O₂ NSs)and gold nanoparticles(Au NPs).It achieve the delivery of the tumor suppressor gene-let-7a to cancer cells and realize the visualization detection,situ fluorescence imaging and regulation of cancer-related genes mi RNA-21,human telomerase reverse transcriptase(h TERT)and glutathione peroxidase 4(GPX4)m RNA by antisense nucleotide technology At the same time,the effectiveness in inhibiting cancer cell proliferation of up-regulating tumor suppressor genes or down-regulating oncogenes was studied,and part of the work was verified in vivo.(1)It is reported that let-7 mi RNA is closely related to the suppression of strong oncogenes such as MYC,KRAS and HMGA2.Let-7a in its family is the main tumor suppressor.We combine the FAM-labeled let-7a mi RNA with on Mn O₂ NSs,it forms FAM-let-7a/Mn O₂ NS probes.The probes enter cell through endocytosis,then Mn O₂ NSs degrades into manganese ions(Mn²⁺)under the action of intracellular GSH,then release FAM-let-7a and restore fluorescence signal.Because of let-7a content rising,it induces cancer cell apoptosis.(2)Telomerase is actively expressed in cancer cells.The treatment of telomerase is a new and specific treatment.And mi RNA-21 has been proven to indirectly down-regulate h TERT and play a synergistic effect in telomerase treatment.We have synthesized AS1411-Au NP-probe which combines two nucleic acid hybrid sequences and contains targeted sequences.The AS1411 of probe improves the targeting and uptake rate of cancer cells.Nucleotide technology down-regulates the expression of h TERT m RNA and mi RNA-21 in cancer cells,then promotes cancer cell apoptosis.Studies have shown that the AS1411-Au NP-probe exhibits a good anti-cancer effect whether it inhibits the proliferation of cancer cells in vitro or inhibits the growth of tumors in vivo.(3)Ferroptosis is a new form of cell death that has been explored recently.The characteristics of the tumor microenvironment are more conducive to the occurrence of ferroptosis.The investigation of ferroptosis cannot bypass its central node GPX4,but the existing enzyme inhibitors all have problems such as poor pharmacokinetics,toxicity,and poor solubility.The safety of Au NP-probe has always been recognized.We have constructed an Au NP-probe that combines antisense oligonucleotide technology to down-regulate GPX4 m RNA in cancer cells,thereby inhibiting the expression of GPX4.Experiments show that the probe can effectively down-regulate the content of GPX4m RNA in cancer cells and inhibit the expression of GPX4.It is a relatively safe and promising GPX4 inhibitor,which is expected to be used in ferroptosis to promote apoptosis of cancer.