Effects Of Fullerenols On Proliferative Inhibition And Apoptotic Induction In Human Chronic Myeloid Leukemia (K562) Cells

Chronic myeloid leukemia（CML）is a clonal hematologic malignancy derived from bone marrow pluripotent stem cells proliferation disorder,accounting for 20%of leukemias in adult.Current chemotherapeutic agents are limitedly efficient,non-specific target,lack of selective tumor uptake,poor pharmacokinetic or ultrahigh toxicity profiles,and drug resistance occurrence in the process of killing tumor cells,affect both normal and cancerous cells,seriously narrowing their therapeutic window and clinical use.Novel nano-scale polyhydroxy fullerenols C₆₀（OH）_n and Gd@C₈₂（OH）_n（18≤n≤24）,which is a water-soluble targeting carbon pharmaceutical,have been widely concerned because of their unique chem-physical properties,and exhibit good potential for application in the field of biomedicine.Moreover,systemic and thorough research on the anticancer activity in vitro of C₆₀（OH）_n and Gd@C₈₂（OH）_n against human chronic myeloid leukemia carcinoma K562 has hardly any by far.Accordingly,this paper conducts research in two areas:the action mechanism of fullerenols to serum albumin and the effect of fullerenols on human chronic myeloid leukemia（K562）cells.The specific contents are as follows:Part Ⅰ of this article（review）summarizes in detail various properties of fullerene derivatives,and their toxicity in cells.Their potential antineoplastic activities,possible mechanisms,as well as special applications in photodynamic therapy and drug delivery systems are also been introduced.This section is to demonstrate that,fullerene derivative nanoparticles have potential in tumor therapy.Meanwhile,it proves the importance of fullerene derivative nanoparticles in clinical or biomedical fields,but also point out challenging parts currently present.Part Ⅱ of this article investigates the interaction between Gd@C₈₂（OH）₂₂ and serum albumin（HSA and BSA）affinities using by spectroscopic analysis.From the characteristic feature of fluorescence quenching spectra at different temperatures,the inherent binding information including quenching mechanism,association constants,number of binding site,fraction of initial fluorescence and basic thermodynamic parameters were calculated.The binding of Gd@C₈₂（OH）₂₂ to serum albumin caused strong quenching of protein intrinsic fluorescence and the structural changes of serum albumin.Within the lower scope of concentration,Gd@C₈₂（OH）₂₂2 was likely to rise fluorescence quenching of serum albumin through individual static quenching process by forming a ground-state complex,while dynamic and static coexisting quenching mechanism occurred in high concentration.Binding sites of BSA were slightly more than those of HAS,and all of them reached to 1;the distance r between donor and acceptor was found to be 3.1494 nm and 3.6479 nm for HSA and BSA,respectively,both of which were fewer than 7 nm.It is confirmed that binding interaction for proteins in the presence of drugs was strong,the binding ratio was 1:1,and non-radiative energy transfer from protein to drug was extremely high probability in lower density.Binding process of Gd@C₈₂（OH）₂₂-HSA was driven mainly through van der Waals forces and hydrogen bonding formation,however more likely to be electrostatic interaction involved in the Gd@C₈₂（OH）₂₂-BSA binding process;Binding sites of Gd@C₈₂（OH）₂₂2 to serum albumin were near tryprophan（HSA）and tyrosine residues（BSA）,respectively.Moreover,a theoretical model of predicting the binding rate of drug to serum albumin was estimated,further analyzed that the binding rate was dynamically altered in various dose of protein and drug.Part Ⅲ of this article observed the effects of fullerol C₆₀（OH）_n on the biological characteristics of chronic myelogenous leukemia cell line K562,such as cell proliferation,cycle and apoptosis.Results showed that C₆₀（OH）_n could significantly inhibit the growth of K562 cells through arresting cells in G2/M phase,reducing the mitochondrial membrane potential and inducing cell apoptosis.And the inhibitory rates were dosage and time dependent.C₆₀（OH）_n treated K562 cell ultrastructure displayed dramatic changes,such as the visible nuclear condensation,margination and apoptotic body formation.Part Ⅳ of this article also explores the antiproliferative activities and its relationship with the cell cycle and apoptosis through the intervention of the human K562 myeloid leukemia cell line using Gd@C₈₂（OH）_n nanoparticles in vitro,in order to analyze the efficacy of Gd@C₈₂（OH）_n on the proliferation inhibition and apoptosis induction of K562 cells involved which signal transduction pathways.In vitro anti-cancer test has preliminarily confirmed that metallofullerenols Gd@C₈₂（OH）_n also showed a dose-response relationship with a certain inhibitory effect on the proliferation and apoptosis of human myelogenous leukemia K562 cells.