L-mimosine Inhibits Head And Neck Squamous Cell Carcinoma Cells Proliferation And Induces Cells Apoptosis

Objective:Squamous cell carcinoma of the head and neck(HNSCC)was usually found in head and neck malignant tumors.HNSCC ranked No.6 in malignant tumors,including the malignant tumors occurred in the oral cavity,pharynx,larynx,nasal cavity and paranasal sinuses etc.More than 50 million new patients were diagnosed each year all over the world.Head and neck squamous cell carcinoma often occurred in the oral and throat mucosa,and there was not any biomarkers could be utilized to diagnose it early.The location of the disease was more hidden than other diseases and the clinical symptoms were not typical in early stage,so it was difficult to be found early.Approximately more than 50%of the patients with head and neck squamous cell carcinoma were found in the advanced stage.Most of them had got lymph node and distant metastasis in this stage,then they would bring many difficulties for clinical treatment.Although surgery and radiotherapy technology had been made great progress and had been introduced to treat head and neck squamous cell carcinoma,the therapeutic effect was not satisfied with the people and the prognosis was poor.5 years survival rate was less than 50%.Thus the chemical therapy is still essential for the clinical treatment of head and neck squamous cell carcinoma.It was particularly important to search for effective,less toxic side effects,targeted chemotherapy drugs.Intracellular superabundant iron was harmful to cells,such as increasing intracellular reactive oxygen species,which might cause DNA damage,cell protein and lipid damage,result in cell apoptosis and gene mutation.Iron chelator could chelate intracellular excess iron,thereby inhibit the activity of ribonucleotide reductase,even affect the synthesis and repair of DNA.Other intracellular protein or gene which regulated by the level of iron,such as anti-oncogene p53,cell cycle protein,cell cycle dependent protein kinase and hypoxia inducible factor alpha etc,also were affected by iron chelator chelating iron.These effects of iron chelators could inhibit the proliferation of tumor cells and promote the apoptosis rate of tumor cells.L-mimosine which extract from Mimosa plant was a plant amino acids.The structure of 1-mimosine was with a high degree of similarity with thymine which could inhibit the tumor cell cycle and promote apoptosis rate of tumor cells with antitumor activity.But the specific antitumor mechanism was unclear.The objective of this experiment was designed to research whether sinistral mimosine could induce apoptosis of head and neck squamous cell carcinoma cells and the mechanism of apoptosis induced by sinistral mimosine in head and neck squamous cell carcinoma.Methods:Human pharyngeal squamous cell carcinoma FaDu cell lines,human tongue squamous cell carcinoma cell Cal-27 cell lines and human normal liver cell L-02 cells lines were cultured and passaged.The inhibiting action of levo mimosine to each kind of cell lines growth was observed by inverted microscope.Flow cytometry was used to detect the apoptosis effects after different concentrations of sinistral mimosine treating pharyngeal squamous cell carcinoma FaDu cells,human tongue squamous cell carcinoma Cal-27 cells and human normal liver L-02 cells respectively,and the apoptosis rates after ferric ammonium citrate and sinistral mimosine disturbing pharyngeal squamous cell carcinoma FaDu cells and tongue squamous cell carcinoma Cal-27 cells.Cell growth activity was examined by CCK-8 method after different concentrations of sinistral shame potash processing pharyngeal squamous cell carcinoma FaDu cells and the interference effect of ferric ammonium citrate on the left-hand mimosine to FaDu cells.The impact of Caspase3/7 activity was observed by using fluorescence microscopy with different concentrations of sinistral mimosine treating tongue squamous cell carcinoma Cal-27 cell lines.Western blot was used to detect the protein expression of Bcl-2,Bax,Bak,Bid,Bik,P13kp110a,PI3kp110b,p-GSK3b,p-P38,p-NFkBp65,p-ERK,p-JNK,p-Histone-H2AX,p-mTOR,p_ATM,p-ATR etc,with different concentrations sinistral mimosine interventing human pharyngeal squamous cell carcinoma FaDu cell lines.Results:The growth of human pharyngeal squamous cell carcinoma FaDu cells and human tongue squamous cell carcinoma Cal-27 cells could be inhibited by sinistral mimosine.Sinistral mimosine could induce apoptosis of human pharyngeal squamous cell carcinoma FaDu cells,and human tongue squamous cell carcinoma Cal-27 cells in a concentration dependent manner.The anti-apoptosis effects of sinistral mimosine to human pharyngeal squamous cell carcinoma FaDu cells and human tongue squamous cell carcinoma Cal-27 cells could be inhibited by a certain amount of ferric ammonium citrate.With the increasing of sinistral mimosine concentration,the expressions of protein Bcl-2,p-ATR decreased,while the protein Bax,Bak,Bid,Bik,P13kp110a,P13kp110b,p-GSK3b,p-P38,p-NFkBp65,p-ERK,p-JNK,p-Histone-H2AX,p-mTOR,p-ATM etc,expressed at high levels.Conclusions:Apoptosis of human head and neck squamous cell carcinoma cell lines could be induced by sinistral mimosine.The potential mechanism of apoptosis induced by sinistral mimosine might be the role of chelation of sinistral mimosine,disturbing intracellular iron metabolism and causing DNA damage in human head and neck squamous cell carcinoma cells.DNA replication and transcription in carcinoma cells were broke by 1-mimosine,leading to apoptosis in the end.