PURPOSE: Therapeutic selectivity is one of the most important considerations in cancer chemotherapy. The design of therapeutic strategies to preferentially kill malignant cells while minimizing harmful effects to normal cells depends on our understanding of the biological differences between cancer and normal cells. We have previously demonstrated that certain agents generating reactive oxygen species (ROS) such as 2-methoxyestradiol (2-ME) preferentially kill human leukemia cells without exhibiting significant cytotoxicity in normal lymphocytes. The purpose of the current study was to investigate the biochemical basis for such selective anticancer activity. METHODS: Flow cytometric analyses were utilized to measure intracellular O(2)(-) levels and apoptosis. MTT assays were used as indicators of cellular viability. Western blot analysis was used to measure the expression of antioxidant enzymes in cancer and normal cells. RESULTS: Malignant cells in general are more active than normal cells in the production of O(2)(-), are under intrinsic oxidative stress, and thus are more vulnerable to damage by ROS-generating agents. The intrinsic oxidative stress in cancer cells was associated with the upregulation of SOD and catalase protein expression, likely as a mechanism to tolerate increased ROS stress. The increase in SOD and catalase expression was observed both in primary human leukemia cells and in primary ovarian cancer cells. Both malignant cell types were more sensitive to 2-ME than their normal counterparts, as demonstrated by the significant accumulation of O(2)(-) and subsequent apoptosis. The administration of ROS scavengers in combination with 2-ME prevented the accumulation of O(2)(-) and abrogated apoptosis induction. CONCLUSIONS: O(2)(-) is an important mediator of 2-ME-induced apoptosis. The increased oxidative stress in cancer cells forces these cells to rely more on antioxidant enzymes such as SOD for O(2)(-) elimination, thus making the malignant cells more vulnerable to SOD inhibition than normal cells.
PURPOSE: Therapeutic selectivity is one of the most important considerations in cancer chemotherapy. The design of therapeutic strategies to preferentially kill malignant cells while minimizing harmful effects to normal cells depends on our understanding of the biological differences between cancer and normal cells. We have previously demonstrated that certain agents generating reactive oxygen species (ROS) such as 2-methoxyestradiol (2-ME) preferentially kill humanleukemia cells without exhibiting significant cytotoxicity in normal lymphocytes. The purpose of the current study was to investigate the biochemical basis for such selective anticancer activity. METHODS: Flow cytometric analyses were utilized to measure intracellular O(2)(-) levels and apoptosis. MTT assays were used as indicators of cellular viability. Western blot analysis was used to measure the expression of antioxidant enzymes in cancer and normal cells. RESULTS: Malignant cells in general are more active than normal cells in the production of O(2)(-), are under intrinsic oxidative stress, and thus are more vulnerable to damage by ROS-generating agents. The intrinsic oxidative stress in cancer cells was associated with the upregulation of SOD and catalase protein expression, likely as a mechanism to tolerate increased ROS stress. The increase in SOD and catalase expression was observed both in primary humanleukemia cells and in primary ovarian cancer cells. Both malignant cell types were more sensitive to 2-ME than their normal counterparts, as demonstrated by the significant accumulation of O(2)(-) and subsequent apoptosis. The administration of ROS scavengers in combination with 2-ME prevented the accumulation of O(2)(-) and abrogated apoptosis induction. CONCLUSIONS:O(2)(-) is an important mediator of 2-ME-induced apoptosis. The increased oxidative stress in cancer cells forces these cells to rely more on antioxidant enzymes such as SOD for O(2)(-) elimination, thus making the malignant cells more vulnerable to SOD inhibition than normal cells.
Authors: Zhaoyun Liu; Jin Chen; Honglei Wang; Kai Ding; Yanqi Li; Anya de Silva; Varun Sehgal; Jonathan Lvan Burbano; Radhika Sundararaj; Janani Gamage; Victor Audu; Rong Fu Journal: Am J Transl Res Date: 2017-12-15 Impact factor: 4.060
Authors: Yun Ge; Idalia Montano; Gabriella Rustici; Wendy J Freebern; Cynthia M Haggerty; Wenwu Cui; Damaris Ponciano-Jackson; G V R Chandramouli; Erin R Gardner; William D Figg; Mones Abu-Asab; Maria Tsokos; Sharon H Jackson; Kevin Gardner Journal: Blood Date: 2006-08-29 Impact factor: 22.113
Authors: Richard D Dinnen; Yuehua Mao; Wanglong Qiu; Nicholas Cassai; Vesna N Slavkovich; Gwen Nichols; Gloria H Su; Paul Brandt-Rauf; Robert L Fine Journal: Mol Cancer Ther Date: 2013-10-14 Impact factor: 6.261