Quantiative Proteomics Of Liver Immortalized Cell Line Chang Liver And Liver Cancer Cell Line HepG2

Objective: To identify differential proteins which may exert function in hepatocarcinogenesis, resistant to chemotherapy, metastasis, recurrence after surgical hepatectomy and other pathological processes, quantitative proteomics of liver immortalized cell line Chang Liver and liver cancer cell line HepG2 using stable isotope dimethyl labeling was profiled. Meanwhile, stable isotope dimethyl labeling provided us the basic methodology for quantitative proteomics of cancer.Methods: Quantitative proteomics of proteolytic digests of proteins extracted from liver liver immortalized cell line Chang Liver and cancer cell line HepG2 was profiled based on strong cation exchange chromatography and reversed phase chromatography(SCX-RPLC) platform coupled with 2D nano HPLC-MS/MS using stable isotope dimethyl labeling. Stable isotope dimethyl labeling was using light-labeling formaldehyde(CH₂O) and heavy-labeling formaldehyde (CD₂O) label the two cellular proteolytic peptides respectively.Result: 3052 peptides corresponding 1006 proteins were successfully quantified. 519(51.6%)proteins were quantified by at least two peptides, 326(32.4%) proteins were quantified by at least three peptides,217(21.6%) proteins were quantified by at least four peptides. Among those 326 proteins, 159(48.8%)up-regulated proteins had changed their quantity 1.5 folds (D/H>1.5) and 77(23.6%)down-regulated proteins had changed their quantity 1.5 folds (D/H<0.67). 122 up-regulated proteins (define D/H>1.5) and 66 down-regulated proteins (define D/H<0.67) were obtained through Gene Ontology(GO) database comparison. Totally 188 differential proteins were identified.Conclusions: 1. Quantitative proteomics of proteolytic digests of proteins extracted from liver immortalized cell line Chang Liver and liver cancer cell line HepG2 was profiled based on strong cation exchange chromatography and reversed phase chromatography(SCX-RPLC) platform coupled with 2D nano HPLC-MS/MS using stable isotope dimethyl labeling. Stable isotope dimethyl labeling was using light-labeling formaldehyde(CH₂O) and heavy-labeling formaldehyde (CD₂O) label the two cellular proteolytic peptides respectively. Totally 188 differential proteins were identified which may exert function in hepatocarcinogenesis, resistant to chemotherapy, metastasis, recurrence after surgical hepatectomy and other pathological processes. The quantitative proteomics yields abundant bioinformatics for further studying.2. Stable isotope dimethyl labeling is a very effective,straightforward and fast method based on chemical labeling in quantitative proteomics. The workflow of quantitative profile using stable isotope dimethyl labeling cellular proteins is the basis of methodology for cancer research.