| Colorectal cancer(CRC)is one of the common gastrointestinal malignancies and has become the second leading cause of cancer-related deaths in the world in recent years.The analysis of the key proteins and its related biological processes involved in the development of CRC has important implications for the prevention and treatment of colorectal cancer.Quantitative proteomics based on High-performance liquid chromatography coupled with mass spectrometry is a powerful tool,which has strongly promoted the development of cancer-related research,and laid a foundation for the unbiased measure the expression of thousands or even tens of thousands of proteins in cancer samples with its high throughput and high coverage.In this study,quantitative proteomics was used to investigate the dynamic expression of proteins during the early onset and metastasis of colorectal cancer at the level of cell lines,pathological tissues,peripheral blood and monocytes.Firstly,at the cellular level,we performed quantitative proteomic studies on seven common colorectal cancer cell lines,and discovered the differentially expressed proteins between metastatic and primary cell lines,and between cell lines from different metastatic organs.Based on the discovery that fatty acid β oxidation(FAO)pathway was up-regulated in metastatic colorectal cells lines,the significance of high expression of the key enzyme ACAA2(3-ketoacyl-Co A thiolase,mitochondrial)of FAO pathway in liver-metastatic KM12 SM cell line was preliminically studied.Using the method of molecular biology,biochemistry and protein mass spectrometry,we found the expression of ACAA2 was induced by detached culture,and was also associated with oxidative phosphorylation and tricarboxylic acid cycling(TCA)pathways involved in cell viability maintenance in KM12 SM cell lines.While transient overexpression of ACAA2 in primary cell line HCT116 didn’t obviously affect the process related to metastasis initiation.Secondly,at the pathological tissue level,we performed a TMT labeled quantitative proteomics study on 54 patients with lymphovascular and perineural invasion or distal metastasis of colorectal cancer.For the samples associated with lymphovascular and perineural invasion,we performed an integrated analysis of our proteome quantitative results with TCGA transcriptomic data and constructed a combined m RNA survival model to predict the prognosis of the patients,the quality of the model was fully evaluated.For paired metastases and primary samples,we sought the differentially expressed proteins and biological processes in both global and liver-specific metastasis,and we also focused on the expression patterns of m RNA corresponding to highly activated metabolism-related proteins in liver metastasis in different organs and the application of these m RNAs in constructing a logistic classification model to distinguish liver metastasis from primary tumor.In addition,by constructing a single-amino acid-mutated driver protein sequence database,we succussed to quantify the expression level of mutated driver proteins in primary tumor and precancerous tissues from CPTAC data and the matched metastatic and primary tissue from our TMT experiment.By comparing the expression patterns of normal and mutated driver proteins in different samples,we analyzed the expression characteristics of mutated driver proteins at different cancer development stages.Finally,at the blood samples’ level,we studied the differentially expressed proteins between early CRC patients and healthy control derived from plasma and peripheral blood monocyte sample,and used computational and experimental methods to screen the internal reference proteins and compare the removal efficiency of different depletion methods for high abundance proteinIn summary,we use quantitative proteomic method to explore the key proteins and biological processes related to early onset and progression of colorectal cancer at multiple levels,and these results can refine our understanding of the of colorectal cancer. |
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