By: Ines Batinic-Haberle and Ivan Spasojevic
After 20 years of bench and preclinical work on Mn porphyrins (MnPs), we are thrilled to see that our compounds have finally reached maturity and entered four clinical trials. We have first designed, synthesized and characterized numerous MnPs, FePs and other metal complexes, which allowed us to establish structure-activity relationship for their SOD-like activities and identify cationic charges in ortho nitrogen positions of peripheral pyridyl groups of MnPs as a key property that enables their high ability to catalyze O2.- dismutation.
Since then, three lead drugs have been most frequently studied: MnTE-2-PyP5+(AEOL10113, BMX-010), MnTnHex-2-PyP5+ and MnTnBuOE-2-PyP5+(BMX-001) (Figure, R, ortho pyridyl substituents are ethyl, n-hexyl and butoxyethyl, respectively). BMX-001 is now tested on suppression of normal tissue injuries in three clinical trials concerning the treatment of various cancers (submitted for publication). Originally designed as SOD-mimics, the biologically compatible reduction potential of Mn in MnP enables broad interactions with other species and redox signaling pathways. In collaboration with Tome’s group, we demonstrated catalysis of S-glutathionylation of Cys residues of NF-кB by MnP/H2O2/GSH, leading to NF-кB inactivation. In addition to NF-кB, S-glutathionylation of Cys was also demonstrated for signaling proteins in our redox proteomics study on 4T1 breast cancer cells treated with the MnP/ascorbate source of H2O2: p38MAPK, protein phosphatase 2A, Keap1, peroxiredoxins 5 and 6, glutaredoxin 3 and 5 and thioredoxin 1, etc.
Most recently, in a comprehensive mouse breast cancer cellular and mouse study, we explored cationic MnPs (BMX-001, BMX-010), GC4403 (analog of GC4419), Mn(III) salen (EUK-8) and a porphyrin-based but not an SOD mimic, yet frequently studied, anionic MnTBAP3-. Only cationic MnPs, which catalyze ascorbate oxidation and protein S-glutathionylation, radiosensitize breast cancer to radiation, and ascorbate enhances such effect (Tovmasyan et al, Antioxid Redox Signal. 2018 Feb 1. doi: 10.1089/ars.2017.7218). Altogether, our studies show that S-glutathionylation of Cys residues is a major mechanism of action of MnPs. Multiple studies by us and others have shown that the more potent the SOD mimic is, the more reactive it is and the larger are its beneficial therapeutic effects whereby it protects normal tissue from oxidative stress injury while suppresses tumor growth (Figure).
Our pharmacokinetic and efficacy studies showed that differential effects originate from distinct partition of MnP in tissues as well as from tissue-specific redox environments. While therapeutic effects are those commonly associated with antioxidants, the mechanism of action associated with our MnPs is pro-oxidative – we thus tend to call such compounds more correctly redox-active therapeutics than antioxidants.
Departments of Radiation Oncology1 and Medicine2, 3PK/PD Pharmaceutical Shared Resource, Duke Cancer Institute, Duke University School of Medicine, Durham, NC 27707, USA
By Dr. Marcus S. Cooke, Ph.D., FRCPath of Florida International University
Luke Skywalker: “I won't fail you! I'm not afraid.”
Yoda: “Oh! You will be. You will be.”
Similar to Luke’s training by Yoda, the PhD is like an apprenticeship, students are mentored and supported throughout, but this is gradually withdrawn, as they become more accomplished, culminating with being an expert in the field, and an independent researcher. On this basis, selection of the right supervisor for you is as vital as selecting the right project area. The successful pursuit of a doctoral degree is a two-way street that requires good alignment between your objectives and those of your supervisor, as well as your progressive capacity to deal with failure and rejection (it’s a fact of life for researchers, I’m afraid).
A PhD requires fulltime dedication to the project. Before considering undertaking a PhD a prospective student must be willing to devote themselves to the project, understanding that experiments sometimes require working outside business hours. You may possess a great deal of practical experience, but this experience by itself is not sufficient to earn the degree. The project fails or succeeds based on the effort, and ideas from the student, guided and supported by the supervisor. In order to have the required level of commitment, the chosen project on which you work must really excite you – this will provide the motivation to keep going, particularly when experiments prove challenging (i.e. techniques stop working for no apparent no reason!). There will be lows, but there will also be highs, for example when your abstract gets accepted for an international meeting, or your first manuscript gets accepted (it feels good whether it’s your first or 81st). This strengthening of your character will surely enrich your career and life.
The kinds of wet lab projects offered in the broad area of Biomedical Sciences do not readily lend themselves to a part-time degree, but that is not to say it is not possible. A PhD in the Biomedical Sciences means 3-4+ years of intensive research in the lab – sounds like plenty of time, right? But the time flies by in which you must have generated a significant amount of novel data, addressing an important research question. Also, don’t think that a PhD is simply an extension of a Master’s degree, only longer. It is completely different, with objectives, timelines and expectations of progress toward scientific independence that are not seen at the Master’s level.
Good organization of personal time will be needed, such that you can improve skills that are just as important as your experimental work. This includes: keeping up with the literature about the subject, improving scientific writing, cultivating attention to detail, attending seminars and workshops in and outside your institution, and very importantly, mastering your own oral communication skills. Most institutions demand a minimum of two original data manuscripts, and a review article to submit towards your PhD. These will need to survive the scrutiny of peer review, which will train your capacity to receive criticism and to work proactively on improving the quality of your research.
A huge amount of self-motivation is required to withstand the intrinsic challenges of developing a scientific project toward thinking independently. The structured, taught element of the PhD is minor, in comparison to the time spent in the lab, and just provides a general grounding to get improve your knowledge base. The real learning and training comes in the lab where research skills are learnt firsthand, and tested on a regular basis through the experiments required to test your hypothesis.
Still wanting to do a PhD in the Biomedical Sciences? Get in touch with prospective mentors, discuss with them theirs and your research and career expectations, and go for it! If you are intrinsically thrilled to investigate Nature, you will not be hampered by the high level of commitment required in this career path. With the right PhD training (irrespective of the discipline), you will be well prepared for a wide variety of career options, though giving you skills which allow you to think, speak, write, and problem-solve in a particular way that makes you an asset to any organization.
By: Alicia J. Kowaltowski, M.D., Ph.D., Universidade de São Paulo
Obesity enhances the incidence and prevalence of many diseases, but is still increasing worldwide. Our group is focused on understanding mechanisms involved in the protective effects of maintaining a normal body weight, in order to uncover new targets for obesity-related diseases. We do this by studying rodents that eat ad libitum (as much as they want) and develop obesity versus animals on a calorically-restricted diet. Calorically-restricted rodents have been shown to have less oxidative damage and age-related diseases, as well as extended lifespans.
Many of the effects of caloric restriction, predictably, involve changes in energy metabolism and mitochondria, the central hub of energy metabolism. Recently, while investigating mechanisms in which calorie restriction prevents excitotoxic neuronal death (Amigo et al., 2017), we found that mitochondria from calorically-restricted animals can take up Ca2+ ions faster and in larger quantities. The higher buffering capacity these mitochondria have promotes protection against neuronal death caused by excessive Ca2+ in the cytosol.
Because this is a completely new effect of caloric restriction, we decided to investigate if mitochondrial Ca2+ uptake was also modified in the liver (Menezes-Filho et al., 2017). We found that liver mitochondria from calorie restricted mice could also take up more Ca2+, and that this was related to protection against ischemic damage. Overall, the finding that caloric intake affects mitochondrial Ca2+ uptake is interesting because Ca2+ is a well-known modulator of energy metabolism and mitochondrial oxidant production. Based on these initial findings, we hope to uncover more connections between metabolic regulation, redox state, caloric intake and Ca2+ in futures studies.
While studying calorically-restricted mice, we noticed that they had different fur from obese ad libitum fed animals. We then decided to investigate changes in the skin and fur of calorie restricted animals, and found many modifications, both in the structure and metabolism of the skin. One interesting finding was that the fur in calorically-restricted mice has a higher insulation capacity, and is necessary for them to thrive: shaving calorie restricted animals makes them lose muscle mass. We are not sure how these results relate to humans, who aren´t very furry, but believe this is an evolutionary adaptation to deal with heat loss. Although the skin is our largest organ, it is not often studied, and there are almost no related findings. We hope that with this study and the development of methodology to monitor metabolism in the skin, more interest will arise.
Amigo I, Menezes-Filho SL, Luévano-Martínez LA, Chausse B, Kowaltowski AJ. Caloric restriction increases brain mitochondrial calcium retention capacity and protects against excitotoxicity. Aging Cell. 2017 16:73-81.
Forni MF, Peloggia J, Braga TT, Chinchilla JEO, Shinohara J, Navas CA, Camara NOS, Kowaltowski AJ. Caloric restriction promotes structural and metabolic changes in the skin. Cell Rep. 2017 20:2678-2692.
Menezes-Filho SL, Amigo I, Prado FM, Ferreira NC, Koike MK, Pinto IFD, Miyamoto S, Montero EFS, Medeiros MHG, Kowaltowski AJ. Caloric restriction protects livers from ischemia/reperfusion damage by preventing Ca2+-induced mitochondrial permeability transition. Free Radic Biol Med. 2017 110:219-227.
Category: Redox Biology
By: Sam Giordano on behalf of the Trainee Council
Finding a good mentor is challenging…
Being a good mentor is just as challenging, but 2016 SfRBM Mentoring Excellence Award Winner, Dr. Rakesh Patel, a Professor in Pathology from the University of Alabama at Birmingham fits the bill. In fact, Dr. Patel excels at mentoring, but I may be a bit biased having been lucky enough to be his mentee during my graduate training.
We all learn from our mentors, and Dr. Patel said the best advice he received as a mentee was to “always persevere, even when experiments don’t work.” He continued, “always ask questions, be critical of your own work, as well as others and most of all enjoy what you do.”
Dr. Patel hopes that as he mentors his trainees, he continues teaching his mentees these important lessons. He also recommends that when trainees are looking for a mentor, look at your potential mentor’s mentoring track and their mentor’s mentoring track record; it can give great insight into the type of mentor they are and how they support their trainees.
In receiving the 2016 SfRBM Mentoring Excellence Award, Dr. Patel received numerous nomination letters from trainees (and even faculty) from different countries with diverse experiences and backgrounds. When I asked how he mentors such a diverse group of people his advice fit perfectly into the current trends in medicine and science. “To borrow a current buzz term, I always try to ‘personalize’ mentoring. I use the analogy that whatever parenting approach was successful for my older child, rarely works for my youngest, and vice versa.”
Dr. Patel also reminds us that a good mentor considers professional and personal goals of their mentees and takes the time to understand what motivates them. This can help the mentees harness his or her strengths and overcome their weaknesses. He also points out that as the trainees grow and learn, the mentor-mentee relationship will evolve, hopefully in a mutually beneficial way. In a healthy mentor-mentee relationship, honest and open communication is key, and it is the best way to have a successful and long lasting healthy mentoring relationship.
By Luciana Hannibal, Ph.D.
Team success goes hand in hand with the professional development of its members. New employees are selected according to background education (know-how theory), previous accomplishments (know-how experience) and potential (know-how to grow). These important metrics help to recruit candidates who are best suited for the position, and capture them at a stage of high self-motivation and drive. Only a few however, will stand out for their achievements, even when the same selection process has been applied to all. Why? A pool of employees will choose to remain in a professional comfort-zone, meeting personal and team demands satisfactorily. Others will strive to further their professional development and to make a difference in the team. Some will go beyond and prepare themselves to lead their own teams in the future. Even after careful recruitment, a population of talented individuals may however derail from successful career development. A mismatch of talents and projects can hamper advancement regardless of individual mindset. Researchers in leading positions are expected to excel at understanding the scientific problem, providing new ideas and solutions, teaching and supervising, cooperating effectively with internal and external colleagues and recruiting copious amounts of extramural funding. Optimizing self-reliance of the team is thus crucial for individual and collective return on investment, and this involves aligning talents with projects. Team leaders must identify individual strengths to effectively assign project roles, and employees must be visible for their most valuable talents. Self-motivated employees, as they typically land in the new job, constitute an invaluable asset.
Here is a brief guide on how to blend projects with selected talent types: