Could Microgravity One Day Help Treat Cancer?
In anticipation of humans one day traversing and colonizing outer space for extended periods of time, scientists have exposed all sorts of living creatures – from bacteria and bullfrogs to mice and monkeys – to microgravity environments. We know now to expect a variety of biological effects from long-term weightlessness: reduction in bone density, loss of muscle mass, diminished cardiac function, distorted balance, impaired vision – the list goes on.
Researchers from Seoul National University College of Medicine in Korea exposed human Hodgkin's lymphoma cancer cells to a simulated microgravity environment within a clinostat, a spinning lab device commonly used for such a purpose. After two days in simulated microgravity, the cancer cells were compared to control cells allowed to grow at normal gravity.
The scientists found that the cancer cells exposed to microgravity had dysfunctional mitochondria compared to control cells, leading to reduced levels of adenosine triphosphate (ATP). Mitochondria are essentially cellular power plants and ATP is the major source of energy that they produce. Starved of energy, the cancer cells exposed to microgravity started to "eat" themselves in a process called autophagy. Autophagy is an orderly breakdown of cellular parts.
The encouraging findings of the present study may explain those of a previous study. That earlier study showed that microgravity slows the proliferation of lymphoma cells. Moreover, a prior study from 2014 found that microgravity might similarly hinder glioma cancer cells, which affect the brain and spine.
However, the Korean researchers who performed the current study caution that autophagy isn't always a good sign.
"Autophagy may contribute to cancer progression by increasing cell migration and invasion; conversely, it can have an anticancer effect by decreasing cell proliferation, and promoting cancer cell death."
Since the studies were only performed in cell culture over a span of just two days, it's far too early to hail microgravity as a definitive treatment for cancer. More often than not, the hopeful findings from these sorts of experiments do not carry over to animals or humans.
Next up, the researchers should extend the duration of their study and compare microgravity's effects on non-cancerous lymphatic cells, as well.
Source: Ae Jin Jeong, Yoon Jae Kim, Min Hyuk Lim, Haeri Lee, Kumhee Noh, Byung-Hak Kim, Jin Woong Chung, Chung-Hyun Cho, Sungwan Kim & Sang-Kyu Ye. "Microgravity induces autophagy via mitochondrial dysfunction in human Hodgkin’s lymphoma cells." Scientific Reports volume 8, Article number: 14646 (2018)