Screening Of Gastric Cancer Markers And Study On The Application Of Magnetic Nanomaterials In The Diagnosis And Treatment Of Gastric Cancer

The contents of this thesis are divided into two parts:the first part is the screening plasma biomarkers for gastric cancer;the second part is study on the application of gold-magnetic composite nanomaterials in the diagnosis and treatment of cancer.Part 1 Screening Plasma Biomarkers for Gastric Cancer Based on Oncomine DatabaseGastric cancer?GC?is the third leading cause of cancer-related death worldwide,partially due to lack of screening strategies.Thus,there is a stringent need for non-invasive biomarkers to improve patient diagnostic efficiency in GC.Top 3 over-and under expressed?COL6A3?SERPINH1?PLEKHG1?PGA4?KCNE2 and GIF?mRNAs in GC were generated as prospective biomarkers through bioinformatics analysis.The plasma of patients with gastric cancer was used to verify the objective circulating mRNAs.Compared with normal controls,expression levels of COL6A3,SERPINH1 and PLEKHG1 were significantly upregulated in GC plasmas.Receiver-operating characteristic?ROC?curves on the diagnostic efficacy of plasma COL6A3,SERPINH1 and PLEKHG1mRNAs in GC showed that they had a certain diagnostic effect.The diagnostic value of the combination of three genes is obviously superior to that of independent diagnosis.The higher COL6A3 and SERPINH1 levels were associated with lymph node metastasis,advanced age and poor differentiation.But the high expressions of these genes were associated with poor OS.Our results suggested that circulating COL6A3,SERPINH1 and PLEKHG1 mRNAs could be putative noninvasive biomarkers for GC diagnosis and prognosis.Part 2 Study on the Application of Gold-magnetic Composite Nanomaterials in the Diagnosis and Treatment of CancerWith the development of the nanomaterial synthesis technology and the application in the field of biomedicine,the gold-magnetic composite nanomaterial has been widely concerned with its unique properties and in many applications.Integrating multimodal bioimaging and different therapies into one nanoplatform is a promising strategy for biomedical applications but remains a great challenge.Therefore,we use other nanomaterials to combine gold nanomaterials with magnetic particles to achieve better diagnosis and treatment of tumors.We have synthesized two kinds of gold-magnetic composite nanomaterials,including GNR@PPy@Fe₃O₄-FA and Fe₃O₄@HMSN@GNS-PEG@CCM nanocomposites.Importantly,these nanocomposites are successfully utilized for magnetic resonance?MR?,computed tomography?CT?and photoacoustic?PA?multimodal imaging.Moreover,they enable the integration of photothermal therapy and chemotherapy to receive superior antitumor efficacy.The photothermal efficiency of GNR@PPy@Fe₃O₄-FA and Fe₃O₄@HMSN@GNS-PEG@CCM nanocomposites reach 51.46%and 29.73%.Cell viabilities decrease into about 15%because of the combination of chemo-photothermal therapy effects.In animal experiments,the tumor growth rate of mice treated with Fe₃O₄@HMSN@GNS-PEG-DOX@CCM and near infra-red?NIR?radiation was significantly inhibited compared with the control group.Moreover,these nanocomposites could target to cancer cells under magnetic field,folic acid or cancer cell membrane,and the modification of folic acid and cancer cell membrane make the materials have better biocompatibility.In a word,we have studied the synthesis of two kinds of gold-magnetic composite nanomaterials and their application in the integration of tumor diagnosis and treatment.It provides a reference for the research and development of nanomaterials platform with higher accuracy and better therapeutic effect for tumors.