A characterization of cancerous cells is their ability to metastasize and show up in areas where they do not belong. When a normal cell becomes detached from its environment, a process called apoptosis (cellular self destruction) is triggered.
The genes which would be activated in a normal cell to trigger apoptosis may be damaged and non-functional in a cancerous cell, thereby allowing it to survive the initial detachment from its environment. However, even if apoptosis is not triggered, the cell should die of starvation because it is cut off from its supply of nutrients.
So far, so good – this all fits in well with what we already know about tumor cells. But this study found that there was another way to keep detached cells from dying: give them antioxidants. (They used either N-acetylcysteine or a water-soluble Vitamin E derivative). It appears that oxidative stress is one thing that’s helping to kill off wandering cells. On top of this effect, reactive oxygen species also seem to be inhibiting another possible energy source, fatty acid oxidation. Take away the reactive oxygen species, and the cells are suddenly under less pressure and have access to a new food source.
Clearly, there are serious implications to this research. Right now all we have are more questions and not enough answers.
This looks like a very strong paper to me; there’s a lot of work in it and a lot of information. Taken together, these results suggest a number of immediate questions. Is there something that shuts down normal glucose uptake when a cell is detached, and is this another general cell-suicide mechanism? How exactly does oxidative stress keep these cells from using their fatty acid oxidation pathway? (And how does that relate to normally positioned cells, in which fatty acid oxidation is actually supposed to kick in when glucose supplies go down?)
The biggest questions, though, are the most immediate: first, does it make any sense at all to give antioxidants to cancer patients? Right now, I’d very much have to wonder. And second, could taking antioxidants actually have a long-term cancer-promoting effect under normal conditions? I’d very much like to know that one, and so would a lot of other people.
After this and that exercise study, I’m honestly starting to think that oxidative stress has been getting an undeserved bad press over the years. Have we had things totally turned around?
The exercise study referred to examines whether antioxidants combined with exercise is a formula for failure. After exercising, the body tries to increase the number of mitochondria and it does so by signaling with reactive oxygen species (ROS).
Of course, ROS are also implicated in many theories of aging and cellular damage, which is why cells have several systems to try to soak these things up. That’s exactly why people take antioxidants, vitamin C and vitamin E especially. So. . .what if you take those while you’re exercising?
Once again, the law of unintended consequences rears its ugly head.
And as it turns out, antioxidant supplements appear to cancel out many of the beneficial effects of exercise. Soaking up those transient bursts of reactive oxygen species keeps them from signaling. Looked at the other way, oxidative stress could be a key to preventing type II diabetes. Glucose uptake and insulin sensitivity aren’t affected by exercise if you’re taking supplementary amounts of vitamins C and E, and this effect is seen all the way down to molecular markers such as the PPAR coactivator proteins PGC1 alpha and beta. In fact, this paper seems to constitute strong evidence that ROS are the key mediators for the effects of exercise, and that this process is mediated through PGC1 and PPAR-gamma.
Taking supplemental antioxidants may unnecessary because the body produces enough of its own.
Interestingly, exercise also increases the body’s endogenous antioxidant systems – superoxide dismutase and so on. These are some of the gene targets of PPAR-gamma, suggesting that these are downstream effects. Taking antioxidant supplements kept these from going up, too.
In conclusion, antioxidant supplements will hinder the some of the benefits gained from exercise and likely helps cancerous cells survive and spread around.