Preventative abilities of a ketogenic diet and intermittent fasting in relationship to the carcinogenesis of astrocytoma – Dr Ben Loos
Dr Ben Loos
The preventative abilities of a ketogenic diet and intermittent fasting in relationship to the carcinogenesis of astrocytoma.
The main purpose of this research was to investigate, how cell death induction can be enhanced in brain cancer, by controlling and modulating substrate availability. In particular, the control of autophagy and ketone bodies were investigated. Many state of the art molecular techniques were employed to unravel the mechanisms that govern cell death decision making. It was found that autophagy, a metabolic pathway, as well as ketone body provision sensitizes cancer cells to undergo cell death. Much promise exists in translating the modulation of autophagy and ketone body metabolism to the bedside. Models with strong translational value (glioma-spheres) are recommended, to bring this work closer to the bedside. This is, what we indeed have already initiated (glioma sphere development).
We are satisfied with the work achieved and the promising data generated. Our results show that indeed the use of ketone bodies as well as the use of drugs that modulate autophagy is a feasible avenue to robustly improve the effects of the chemotherapy. (The work on autophagy has received attention due to the Nobel prize receipt to Prof Ohsumi, 2016). Ketone bodies and autophagy change the amount of energy that is available to the cancer cells. A well timed application of the drugs (sequentially) shows the strongest effects in killing the glioma cancer cells. Our research shows that the change in cancer cell metabolism is indeed a very powerful avenue to not only enhance the effects of the chemotherapy, but also to overcome the resistance that the cancer cells show to the chemotherapeutic drug. We also show that the mitochondria, which are critical in metabolism and are at the cross-roads of cellular fate, are highly dynamic, change very fast, which requires a dynamic assessment. We have shown that the use of imaging, and quantification of life microscopy can be very powerful in telling us whether the cancer cell is likely to die or not. Many changes are much faster visible in the image, and only show up later in other tests, that for example assess particular proteins (Western blotting).
We have measured their mitochondrial function, in order to see how well the cancer cells can produce energy and how well they can maintain the cellular metabolism. This assay, termed mitochondrial fission and fusion assay, is very specialized, as we keep the cells alive, force the cells to produce a fluorescent protein, that we can then, with a laser, switch on, and follow. We observe the mitochondria in the living cancer cell, as it is exposed to the drug and ketone bodies. We have successfully (for the first time in South Africa, the student also won a prize – the ‘best method award’ in Sept 2016 for presenting this work at a local conference) set this work up, and generated data that show that the mitochondria in fact respond to changes in autophagy. This is great news, as it shows us that this pathway connects to cell death. Very importanty, we have shown that, if we upregulate autophagy, followed by its inhibition, we can achieve more cell death. This is very important, a concept that we call ‘prefluxing’. This is a new concept, which indicates that, if we increase autophagy before a drug intervention in cancer cells, we can achieve more cell death (sensitize the cancer cells to undergo apoptosis). We have also achieved to show, that the cells where autophagy is inhibited, these mitochondria are very sick, they don’t fuse, and (we believe -and will find out this year), produce less energy. We have measured this mitochondrial function by measuring, how their network looks like. If it is very ‘networky’ (fused), the mitochondria are fine and the cell will live. If the mitochondria become fragmented (fission), the mitochondria are not well, and the cell will die easier. With the system that we have implemented, to measure this fission and fusion behavior, we have now a very fine tool to see how good the drug is in achieving more fission.
We have also measured the amount of ketone bodies needed to give to the cells, so that it mimics the amount of ketone bodies in the blood of a patient who adheres to a ketogenic diet. We have been in contact with a clinician in the US, who already provides chloroquine to glioma patients, in addition to the TMZ drug (Rosenfeld et al., 2014), and this already improves the treatment, and who indicates that a better control over the autophagy system is needed. We believe that upregulation of autophagy through ketone bodies can achieve that.
In summary, our results make us very confident that this approach is feasible and very promising. Given the bleak prognosis for glioma patients, this work deserves further study, to move into an in vivo model for stronger clinical translation. We are hence setting up a 3D gliomal sphere model, that can be derived from commercially or patient derived tumour cells. This will be a major step forward in the glioma research in South Africa. We also see that it is crucial to find a good peripheral marker that tells us about the amount of autophagy systemically. To this end, through a different project, we are building an autophagy nano-sensor.