Reactive Oxygen Species Regulate Caspase Activation in Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand–Resistant Human Colon Carcinoma Cell Lines
Abstract
The effects of reactive oxygen species (ROS) on tumor necrosis factor–related apoptosis–inducing ligand (TRAIL)–induced apoptosis in solid cancers have yet to be clearly defined. In this study, we found that the classic uncoupler of oxidative phosphorylation, carbonyl cyanide m-chlorophenylhydrazone (CCCP), induced a reduction in ΔΨm and generation of ROS. This uncoupling effect enhanced TRAIL-induced apoptosis in TRAIL-resistant human colon carcinoma cell lines (RKO, HT29, and HCT8). Sensitization was inhibited by benzyloxycarbonyl-valine-alanine-aspartate fluoromethylketone, indicating the requirement for caspase activation. CCCP per se did not induce apoptosis or release of proapoptotic factors from mitochondria. Generation of ROS by CCCP was responsible for TRAIL-induced Bax and caspase activation because scavenging ROS completely abrogated apical caspase-8 activation and further downstream events leading to cell death. Overexpression of Bcl-2 did not prevent the initial loss of ΔΨm and ROS generation following CCCP treatment, but did prevent cell death following TRAIL and CCCP exposure. Uncoupling of mitochondria also facilitated TRAIL-induced release of proapoptotic factors. X-linked inhibitor of apoptosis overexpression abrogated TRAIL-induced apoptosis in the presence of CCCP and decreased initiator procaspase-8 processing, indicating that additional processing of caspase-8 required initiation of a mitochondrial amplification loop via effector caspases. Of interest, depletion of caspase-9 in RKO cells did not protect cells from TRAIL/CCCP-induced apoptosis, indicating that apoptosis occurred via a caspase-9–independent pathway. Data suggest that in the presence of mitochondrial-derived ROS, TRAIL induced mitochondrial release of Smac/DIABLO and inactivation of X-linked inhibitor of apoptosis through caspase-9–independent activation of caspase 3. https://cancerres.aacrjournals.org/content/65/16/7436
oncotarget Zoya Demidenko Dr. Zoya N. Demidenko Zoya N. Demidenko , Ph.D. is Executive Manager of the Oncotarget journal . Oncotarget publishes high-impact research papers of general interest and outstanding significance and novelty in all areas of biology and medicine: in translational, basic and clinical research including but not limited to cancer research, oncogenes, oncoproteins and tumor suppressors, signaling pathways as potential targets for therapeutic intervention, shared targets in different diseases (cancer, benign tumors, atherosclerosis, eukaryotic infections, metabolic syndrome and other age-related diseases), chemotherapy, and new therapeutic strategies. After earning her Ph.D. in molecular biology, Zoya was awarded a Fogarty post-doctoral Fellowship from the National Institutes of Health in Bethesda, MD. After successful completion of post-doctoral training, she continued her professional career at George Washington University and Albert Einstein School of Medicine . In 2005 she cofounded the startup company Oncotarget Inc. which is focused on the development of anti-aging and anti-cancer drugs. Her research interests include signal transduction, cell cycle and cellular senescence, and their pharmacological targeting. In 2009 she cofounded the publishing house Impact Journals which specializes in publishing scientific journals. In 2011 she was selected to be a Member of the National Association of Professional Women .
When public speak of today’s medicine, precision plays one of the most crucial roles and people’s lives are directly dependent on it. Likewise, any researches related to medicine are necessary to comply with the highest standards. The problem today is that any results of researches can be published online and used as a reference without being thoroughly verified and validated. Mikhail (Misha) Blagosklonny of Oncotarget clearly understood this problem and decided to create an alternative solution. That’s how a weekly oncology-focused research journal named “Oncotarget” has been founded back in 2010. The major principle of this journal is related to Altmetric scores that are used as a quality indicator. That helps both readers and authors to verify publications with Altmetric Article Reports that provide “real-time feedback containing data summary related to a particular publication.” Oncotarget website provides a complete publications list with corresponding scores higher than 100 as well as reports mentioned above. Mikhail (Misha) Blagosklonny glad to share his new approach and hopes it provides the required assistance to anybody, who has interest in oncology.
“A diagnostic autoantibody signature for primary cutaneous melanoma” has the Altmetric score of 594. This study was released back in 2018 by Oncotarget and completed by different experts from Hollywood Private Hospital, Edith Cowan University, Dermatology Specialist Group, St. John of God Hospital and The University of Western Australia. The introduction of the study discusses “recent data shows that Australians are four times more likely to develop a cancer of the skin than any other type of cancer”, and shares an insight on melanoma that “is curable by surgical excision in the majority of cases, if detected at an early stage.”
The article has got an Altmetric score of 594. Mikhail (Misha) Blagosklonny realizes that majority of readers are willing to comprehend the very meaning of it. Based on the Altmetric website, the score relates to “how many people have been exposed to and engaged with a scholarly output.” Hence, the article about melanoma, was used for citations in different news articles 69 times. In addition, it was quoted in 2 online blogs, as well as 25 Tweets on Twitter and 1 Facebook post. FOX23 of Tulsa, Oklahoma has headlined their report on July 20, 2018 as “New blood test could detect skin cancer early”, using the main content of Australia study
Another Oncotarget’s research with a top score of 476, is “Biomarkers for early diagnosis of malignant mesothelioma: Do we need another moon-shot,”. This study has appeared in 60 news stories, 1 online blog post and 6 Twitter posts. The majority of public may have seen a brief overview only, however those who visit Mikhail (Misha) Blagosklonny at Oncotarget, do receive useful scientific facts. Oncotarget is glad to have the ability to share with online readers this highly appreciated and high-quality information, that is trustworthy and reliable.
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