Hepcidin-Based Nanocomposites For Enhanced Cancer Immunotherapy

Leukemia is a systemic malignant hematological cancer with poor prognosis and high mortality.Among them,acute myeloid leukemia AML)is the most common type of myeloid leukemia.Most AML patients can relieve their symptoms and prolong their survival through targeted therapy and immunotherapy.However,there are more refractory cases in AML patients and a high relapse rate after treatment,and the prognosis of patients is still not ideal.Recently,researchers have discovered that endogenous inorganic elements play a crucial role in the process of life and disease,and exogenous introduction of inorganic small molecule compounds has been widely used in clinical cancer diagnosis and treatment.Among them,iron therapy is a novel anticancer therapeutic strategy utilizing iron-based compounds,which can overcome the chemoresistance of cancer cells.However,cancer cells frequently overexpress ferroportin,causing accumulated iron in the cells to be excreted into the plasma,a process that limits the efficacy of iron therapy and overloads the plasma with iron,which can have toxic effects on the body.Therefore,combining iron therapeutics with iron blockers is a highly effective therapy for AML.In this dissertation,a ferro-therapeutic nanoplatform is designed using fusing Hepcidin which has the function of degrading ferroportin and leukemia cellmembrane vesicles on gold nanoparticles（AuNPs）-loaded hollow mesoporous Prussian Blue（AuPB@LMHep）.AuPB@LMHep specifically targeted leukemia cells through ferroportin and is subsequently internalized and disintegrated into iron and AuNPs through autophagy.Hepcidin blocked ferroportin-mediated iron export and resulted in the accumulation of intracellular iron,while AuNPs induced ferroptosis by depleting glutathione（GSH）.Furthermore,iron accumulation inactivates the endogenous iron-dependent m⁶A demethylase,thereby increasing m⁶A mRNAmediated modification and suppressing m⁶A mRNA methylation-related oncogenes.Finally,AuPB@LMHep can also synergize with PD-L1 antibody to enhance the activity of T cells,thereby enhancing the body’s immune response to leukemia.Our findings provide a new entry point for Hepcidin-based nanocomposites as "epigenetic drugs" and immunotherapeutic agent for the treatment of leukemia.Specific research results are as follow:1.Ferrotherapy utilizes ferrous(Fe²⁺)ions to catalytically break down the high levels of H₂O₂ to cytotoxic hydroxyl radicals（·OH）holds promise for cancer treatment.In addition to triggering oxidative stress and cell death,iron accumulation can inactivate multiple leukemogenic genes by increasing N6-methyladen-osine（m⁶A）modification of the mRNAs and the dysregulation of m⁶A mRNA modification is directly related to the pathogenesis of various cancers and drug response.Several Fe-based nanomaterials have been designed that increase iron levels in cancer cells and enhance their therapeutic clearance.However,overexpression of ferroportin in cancer cells can limit the efficacy of iron therapy.Thus,Therefore,designing a drug that can not only target leukemia cells and block iron export,but also dynamically regulate the modification of m⁶A mRNA in cells is expected to treat leukemia from the root.Herein,we developed a multifunctional biomimetic nanoplatform AuPB@LMHep modified with hepcidin for synergistic iron therapy and m⁶A mRNA modification.Hepcidin is a peptide hormone secreted by the liver in response to iron loading and inflammation.It is internalized upon binding to ferroportin,and thereafter increases iron accumulation and oxidative stress.We coated gold nanoparticles（AuNPs）-loaded hollow mesoporous Prussian blue（HMPB）with hepcidin and leukemic cell membrane-derived vesicles.We perform a series of characterizations on the structure,chemical properties,leukemia cell targeting,drug release,stability,leukemia cell targeting and toxicity.2.Epitranscriptome,also known as RNA epigenetics,is the most active research frontier at the intersection of chemistry,life science and medicine.It mainly studies the structure,stability,function,translation of RNA and how to participate in the evolution of various diseases,represented by m⁶ARNA methylation modification.In order to further understand the mechanism of action of AuPB@LMHep,based on the previous work,we performed transcriptome-wide RNA sequencing of leukemia cells treated with AuPB@LMHep,and explored the intracellular molecular mechanism of its existence.We also established a mouse leukemia model to evaluate the efficacy of AuPB@LMHep,and detected the immune cell components in the mouse bone marrow to determine the potential mechanism of AuPB@LMHep enhanced immunotherapy.In addition,we tested the in vivo biosafety,drug distribution and biocompatibility of the material.The results showed that AuPB@LMHep can enhance the activity of T cells in coordination with PD-L1 antibody,thus enhancing the immune response to leukemia.