An international team of researchers has revealed how aggressive pancreatic cancer cells change their environment to enable easy passage to other parts of the body (or metastasis) - the main cause of pancreatic cancer related death.
The researchers discovered that some pancreatic tumors produce more of a molecule called 'perlecan' to remodel the environment around them, which helps cancer cells spread more easily to other parts of the body, and also protects them against chemotherapy. In a mouse model, the researchers showed that lowering the levels of perlecan revealed a reduction in the spread of pancreatic cancer and improved response to chemotherapy.
The findings are published in the journal Nature Communications.
Pancreatic cancer is one of the most lethal forms of cancer, with a five-year survival of ~9% in Australia. In its early stages, pancreatic cancers often show no obvious signs or symptoms and by the time a cancer is diagnosed, it has often begun to spread outside the pancreas.
The team investigated why some pancreatic cancers spread, while others appear to stay in one place. In their study, the researchers took an unconventional path - they compared the tissue around tumor cells in both metastatic (spreading) and non-metastatic (non-spreading) pancreatic cancers. This tissue - known as the 'matrix' - acts like a glue that holds different cells in an organ or in a tumor together.
Using mouse models, the team extracted fibroblasts (cancer associated fibroblasts, CAFs)- cells that produce most of the matrix - from spreading and non-spreading pancreatic tumors. By mixing these different fibroblasts with cancer cells, the researchers found that remarkably, cancer cells from a non-spreading tumor began to spread when mixed with fibroblasts from a spreading tumor.
"Our results suggest that some pancreatic cancer cells can 'educate' the fibroblasts in and around the tumor. This lets the fibroblasts remodel the matrix and interact with other, less aggressive cancer cells in a way that supports the cancer cells' ability to spread," says first author.
"This means that in a growing tumor, even a small number of aggressive metastatic cells - a few bad apples - can help increase the spread of other, less aggressive cancer cells."
To investigate how to stop pancreatic cancer cells from remodelling the matrix around them, the team took an even closer look at the fibroblasts.
Using state-of-the-art mass spectrometry techniques, the researchers discovered several molecules that the fibroblasts from metastatic tumors produced at significantly higher levels than the fibroblasts from non-metastatic tumors.
"What we discovered is a previously unknown set of matrix molecules that aggressive pancreatic cancer cells use to shape the tissue around them, in order to both protect them from chemotherapy and enable easier escape around the body," explains the senior author.
Using gene-editing techniques, the researchers reduced the levels of one of the molecules called perlecan (heparin sulphate proteoglycan 2, HSPG2) in mouse models of aggressive metastatic pancreatic cancer. Through advanced live imaging techniques, the researchers tracked individual cancer cells and revealed that lowering the levels of perlecan not only reduced the spread of cancer cells, but that tumors also responded better to chemotherapy.
"We believe that there would be important benefit in targeting the fibroblasts of a in combination with targeting the cancer cells themselves with chemotherapy," says the author. "If we can specifically target the aggressive fibroblasts in patients harboring precise genetic changes, we can make them more susceptible to our currently approved treatments, which would significantly change how we treat this aggressive cancer."
The researchers say that targeting perlecan, or other matrix molecules that help remodel the tissue of metastatic tumors, may be effective for not just pancreatic cancer, but also prostate and breast cancers.
Cancer associated fibroblasts (CAFs) role in the metastasis of pancreatic cancer
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