New therapy prevents breast cancer formation in mice

Scientists have developed a novel breast-cancer therapy that partially reverses the cancerous state in cultured breast tumour cells and prevents cancer development in mice.
The therapy could one day provide a new way to treat early stages of the disease without resorting to surgery, chemotherapy or radiation, researchers said.
The therapy was developed by a multi-institutional team led by researchers from the Wyss Institute of Biologically Inspired Engineering at Harvard University.
"The findings open up the possibility of someday treating patients who have a genetic propensity for cancer, which could change people's lives and alleviate great anxiety," said Wyss Institute Founding Director, Don Ingber.

"The idea would be start giving it early on and sustain treatment throughout life to prevent cancer development or progression," Ingber said.
Between breast self-exams, mammograms, MRIs, and genetic tests, more women than ever are undergoing early tests that reveal precancerous breast tissue.

That early diagnosis could potentially save lives; however, few of those lesions go on to become tumours, and doctors have no good way of predicting which ones will. As a result, many women undergo surgery, chemotherapy, and radiation who might never develop the disease.
A therapy that heals rather than kills cancerous tissue could potentially help all these patients, as well as men who develop the disease. But to date the only way to stop cancer cells has been to kill them.

The treatments that accomplish that, including surgery, chemotherapy, and radiation therapy, often damage healthy tissue, causing harsh side effects.
The Wyss Institute researchers thought they could do better by spotting new genes that drive breast cancer and developing targeted genetic therapies to block them.
First they identified the culprit genes among the thousands that are active in a cell at any moment. They spotted more than 100 genes that acted suspiciously just before milk-duct cells in the breast begin to overgrow.
The team narrowed down to a single gene called HoxA1 that had the strongest statistical link to cancer.
The researchers wanted to know if blocking the HoxA1 gene could reverse cancer in lab-grown cells from mouse milk ducts.

Researchers grew healthy mouse or human mammary-gland cells in a nutrient-rich, tissue-friendly gel. Healthy cells ensconced in the gel formed hollow spheres of cells akin to a normal milk duct. But cancerous cells, in contrast, packed together into solid, tumour-like spheres.
Cancerous cells were treated with a short piece of RNA called a small interfering RNA (siRNA) that blocks only the HoxA1 gene. The cells reversed their march to malignancy, stopping their runaway growth and forming hollow balls as healthy cells do.
The siRNA treatment also stopped breast cancer in a line of mice genetically engineered to have a gene that causes all of them to develop cancer.