In a new study, researchers found that the well-known drug tamoxifen could exploit a weakness in the physical ‘scaffolds’ around tumors.
The report’s authors were led by Imperial College London.
They say that following further research, the drug might in future be repurposed to help treat pancreatic cancer as well.
For many years tamoxifen has been used to treat a common form of breast cancer by preventing estrogen.
Estrogen helps breast tumors grow, from reaching cancer cells and encouraging tumor growth.
The research team in the study has demonstrated that in mice, tamoxifen helps change the physical environment, or ‘scaffolding’, in which tumors grow.
This scaffolding regulates scar tissue development, inflammation, and immune responses—three key hallmarks of pancreatic cancer.
The researchers are now keen to explore whether this previously-unseen effect could justify its use in most solid tumors, like those seen in pancreatic cancer.
Pancreatic cancer has a very low survival rate with less than one percent of sufferers surviving for 10 or more years.
Over the last 40 years the survival rate has not significantly changed, and finding an effective therapy is a pressing challenge for cancer researchers.
Most solid tumors, like those seen in pancreatic cancer, are surrounded by a large amount of connective tissue.
The stiff, scar-like tissue stands like scaffolding around the tumor and hinders drug delivery by blocking chemotherapy drugs from reaching the tumor.
It also regulates how tumors grow and spread.
The formation of this connective tissue in pancreatic tumors is driven by pancreatic stellate cells (PSCs), which stiffen the tissue by applying physical forces and remodeling the tissue architecture.
The researchers looked at this scaffolding in mouse pancreatic tumors using a combination of biophysical and cancer biology methods.
They found new insights about how cells that surround pancreatic tumors interact and studied how tamoxifen alters the physical environment around these tumor types.
The first paper shows for the first time that tamoxifen inhibits the ability of PSCs to harden the connective tissue surrounding tumors via a previously unknown mechanism totally different to the known pathway in breast cancer.
By preventing the tumor’s environment from stiffening, tamoxifen regulates the immune response and curbs the invasion and spread of cancer cells.
For the second paper, the researchers studied the role of oxygen in pancreatic cancer.
The cells within pancreatic tumors are exposed to very little oxygen, for which they’ve developed a protective mechanism:
When oxygen levels drop, the cells release molecules called hypoxia-inducible factors (HIF), which help cancer cells survive these conditions.
This paper shows that tamoxifen mechanically inhibits the production of HIFs, leaving the cancer cells vulnerable to low oxygen levels and more likely to die.
The team suggests that cancer research tends to study the genetic influences on specific cancers, but their approach focuses on the physical factors in the environment that affect the growth and spread of tumors.
By studying the environment rather than the genes involved in one cancer, we can reveal important traits common to all cancers, and help to identify more broad-spectrum treatments.
Developing new drugs is expensive and takes many years.
The authors say repurposing an established cancer drug for a different tumor type could help effective treatments reach patients much more quickly and cheaply.
However, they caution that because their work was conducted on cell cultures and mouse models, more research is needed before applying the drug to human patients.
Lead author on both papers is Dr. del Río Hernández.
Their findings are published in EMBO Reports.
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Source: EMBO Reports.