Objective:Recently,a high frequency of mutations in mitochondrial DNA(mtDNA) has been detected in ovarian cancer.To explore the alterations of proteins in mitochondria in ovarian cancer,a pair of human ovarian car-cinoma cell lines(SKOV3/SKOV3.ip1) with different metastatic potentials was examined.Methods:Cancer cells SKOV3.ip1 were derived from the ascitic tumor cells of nude mice bearing a tumor of ovarian cancer cells SKOV3.SKOV3.ip1 exhibited a higher degree of migration potential than its paired cell line SKOV3.The proteins in the mi-tochondria of these two cells were isolated and separated by 2-D gel electrophoresis.The differently expressed pro-teins were extracted and identified using matrix assisted laser desorption ionisation/time-of-flight/time-of-flight(MALDI-TOF/TOF),and finally a selected protein candidate was further investigated by immunohistochemistry(IHC) method in nude mice bearing tumor tissues of these two cells.Results:A total of 35 spots with different expressions were iden-tified between the two cells using 2D-polyacrylamide gel electrophoresis(PAGE) approach.Among them,17 spots were detected only in either SKOV3 or SKOV3.ip1 cells.Eighteen spots expressed different levels,with as much as a three-fold difference between the two cells.Twenty spots were analyzed using MALDI-TOF/TOF,and 11 of them were identified successfully;four were known to be located in mitochondria,including superoxide dismutase 2(SOD2),fumarate hydratase(FH),mitochondrial ribosomal protein L38(MRPL38),and mRNA turnover 4 homolog(MRTO4).An increased staining of SOD2 was observed in SKOV3.ip1 over that of SKOV3 in IHC analysis.Conclusions:Our results indicate that the enhanced antioxidation and metabolic potentials of ovarian cancer cells might contribute to their aggressive and metastatic behaviors.The underlying mechanism warrants further study. Objective: Recently, a high frequency of mutations in mitochondrial DNA (mtDNA) has been detected in ovarian cancer. To explore the alterations of proteins in mitochondria in ovarian cancer, a pair of human ovarian car-cinoma cell lines (SKOV3 / SKOV3.ip1 ) with different metastatic potentials was examined. Methods: Cancer cells SKOV3.ip1 were derived from the ascitic tumor cells of nude mice bearing a tumor of ovarian cancer cells SKOV3.SKOV3.ip1 exhibited a higher degree of migration potential than its paired cell line SKOV3 The proteins in the mi-tochondria of these two cells were isolated and separated by 2-D gel electrophoresis. These-aware pro-teins were extracted and identified using matrix assisted laser desorption ionization / time-of-flight / time-of- flight (MALDI-TOF / TOF), and finally a selected protein candidate was further investigated by immunohistochemistry (IHC) method in nude mice bearing tumor tissues of these two cells. Results: A total of 35 spots with different expression s were iden-tified between the two cells using 2D-polyacrylamide gel electrophoresis (PAGE) approach. Amm them, 17 spots were detected only in either SKOV3 or SKOV3.ip1 cells. Eighteen spots expressed different levels, with as much as a three- fold difference between the two cells. Twenty spots were analyzed using MALDI-TOF / TOF, and 11 of them were identified successfully; four were known to be located in mitochondria, including superoxide dismutase 2 (SOD2), fumarate hydratase (FH) An increased staining of SOD2 was observed in SKOV3.ip1 over that of SKOV3 in IHC analysis. Conclusions: Our results indicate that the enhanced antioxidation and metabolic potentials of ovarian cancer (MRTO3) cells may contribute to their aggressive and metastatic behaviors. the underlying mechanism warrants further study.