Researchers have created the most comprehensive cancer history ever.
They used genetic engineering to cause lung cancer in some very unfortunate mice. Then they took cells from the tumor, sequenced each DNA, and rewound the clock to watch a few malignant cells transform into cancerous tumors that could spread throughout the body.
Their “family tree” provides information about several genes that appear to increase the likelihood that a particular cancer cell likely to survive, thrive, and eventually spread.
“Identifying the relationships between cells in a tumor is important for understanding how cells grow & gaining insight into emergence of aggressive conditions,” said computer scientist Nir Yosef, co-author of the study. It is described in an article published Thursday in the peer-reviewed journal.
Genetic engineering & computational methods gave researchers incredible insight into the tumor development
The researchers created a virus that simultaneously activates mutations that cause lung cancer and turns off a gene that suppresses tumor growth. The virus also allows them to tag each malignant cell with a DNA “barcode” that allows the cell’s descenfants to be traced through the generations. Each time one of the barcode carrying cells divide, the sequence of A, T, C and G molecules in a certain part of its genetic code changes slightly.
Co-author Tyler Jacks said that in these circumstances, the lung tumors in these mice closely resembled tumors developed in humans. “In this model, cancer cells develop from normal cells & tumor progression occurs over a long period of time in its native environment,” he said. “This closely replicates what occurs in patients.”
Insights could one day lead to treatment in humans
When researchers harvest the cells and sequence their DNA, they can use the information to build a family tree of tumor cells. This is valuable information because tumors evolve – at the genetic & gene expression level – as they grow. Family tree allows researchers to determine when and how cancers become more aggressive, more resistant to drugs, and more likely to spread to other parts of the body.
Cancer researcher Jonathan Weissman, another co-author, said: “It was once thought that the key events that made tumors life-threatening were unclear because they were lost in the distant past of the tumor, but this gives us a window into that history.”
Family trees have provided researchers with an important insight into how tumors metasticize, allowing them to spread & grow more tumors elsewhere in the body. The cells most likely to metasticize had descended from aggressive cells that were trying to grow & survive when the tumor was younger. Only in the later stages of the tumor do these lineages begin to metasticize. It turns out that these cells share some of the same genes. This gives researchers developing cancer treatments a number of specific targets.
“In the future, we want to be able to look at the state of cancer cells when a patient comes in and be able to predict how the cancer evolve, what the risk is and how well it can be treated best to prevent that Cancer researcher Dian Yang, another co-author, said: “To develop better therapies, it is important to understand the basic principles that tumors adopt to develop.” .