Scientists Create Breast Tumor Stem Cells

Ince started out with the goal of making a mouse tumor that more closely resembled human tumors than those currently available.

"You want a mouse model that behaves like a human disease from the perspective of what genes are important to target and what drugs will be beneficial," Ince said.

To that end, Ince turned his lab into a sort of a kitchen and tried to improve the liquid media in which tissue is grown. The existing liquid media, he felt, was missing a number of vitamins, hormones and growth factors.

The final concoction contained 75 to 80 different ingredients.

"This took me close to two-and-a-half years. I had nothing to talk about all that time. People wondered what I was doing," Ince said.

But it paid off. He applied genes that had been used for years to transform normal tissue into tumor cells, and the tissue grew.

"The tumors looked much closer to what a human tumor looks like under a microscope," Ince said.

Then the Boston researcher noticed that the tumors he had grown in mice were growing in four to five smaller lumps, instead of one large lump, as is typical.

"That kind of pattern has been associated with metastasis in human patients, so that made me suspect that the tumors that I made with this new sort of cell might, in fact, have the potential to metastasize to distant organs," Ince said.

That's significant, because most tumor models used in the lab do not metastasize. In real life, however, it's these metastases that kill the vast majority of cancer patients.

Ince started injecting fewer and fewer cells into the mice and watching them for longer and longer.

"I still saw tumors when I went down to as few as 10 cells," he said. "Then I watched for 10 to 12 weeks, and I saw small metastases of several cells, micrometastases, in about 75 to 80 percent of the mice."