Upon completion, the CSS will include a cancer research project called “Tumours in Space,” headed by a Canadian researcher based in Norway. The project will examine the roles of both microgravity and cosmic radiation in tumour growth and development. The project is one of just nine selected by the UN Office for Outer Space Affairs (UNOOSA) and the China Manned Space Agency (CMSA) under their programme to provide scientists from all over the world with the opportunity to fly experiments on the CSS.
“The plan is to send three-dimensional stem cell organoids from both healthy and cancer tissue from the same person into space. Here we will study mutations and look at how the cell’s DNA is affected by weightlessness and cosmic radiation,” said the projects principal investigator Tricia L. Larose.
The experiment will rely on three-dimensional cancerous tumours, called organoids. These organoids are grown from adult human stem cells, which are a kind of cell that can divide indefinitely and create different types of cells in doing so. Researchers have perfected their ability to grow organoids so they actually form tiny structures that mimic different organs. Larose theorises that the cancer organoid growth will slow or stop when they are not affected by Earth’s gravity. Previous research on two-dimensional cells has shown that weightlessness has an influence on gene expression linked to tumour development.
“When we look at mutational signatures in cancer cells, there is a lot of ‘noise’. The noise is something we simply do not know a lot about,” she said. “Part of my experimental process is identifying new causes of that noise, and some of that might be gravity”
Her theory is that some of the unknown “noise” in the cancer cells is there as a result of gravity. Since both healthy cells and cells with cancer are affected by gravity, the researchers should be able to detect this in the fingerprints in all our cells.
“I’m looking for the molecular fingerprint for the gravitational force,” she said; this could help explain the meaning of some of the noise in the cancer cells.
She added that the mutational signature of gravity has never been studied or even proposed as a concept. The experiment will also test how cosmic radiation affects the DNA of the healthy organoids and whether this leads to mutations and cancer. The various causes of cancer, such as smoking, UV radiation and ionizing radiation, also leave mutational signatures. Identifying mutational signatures from cancer-causing exposures can be used for risk prediction, eventually leading to better diagnostics and therapeutics.
“My ground-based research with ionising radiation will also help us understand the side effects of radiation therapy for cancer patients on Earth,” she said.
The studies of cosmic radiation will also help with understanding the cancer risk for astronauts on long-duration missions in the space station, or longer journeys, such as to Mars.
“The biggest challenge with human spaceflight and exploration for long-duration missions to Mars and beyond, is the cancer risk for crew due to exposure of cosmic radiation. By identifying the mutational signature of cosmic radiation and comparing that to the known signature of ionising radiation, we may be better able to predict risk and protect crew on a long-duration space mission” Larose said.
It is thought that astronauts on a mission to Mars would be exposed to at least 60 per cent of the total radiation dose limit recommended for their career during the journey alone to and from the Red Planet.