Biology – Scientific Reporting in the News Media

Read the article below, and then answer the questions that follow.

E. Coli Kills Cancer

Cancer is often fought with chemotherapy, and the effects of these toxic drugs can be excruciating. But

Canadian researchers have discovered that a familiar, yet potent toxin can actually shrink brain tumors in

less than 48 hours with no apparent ill effects.

The cancer-fighting chemical is verotoxin, which is produced by the ubiquitous E.coli bacteria. This toxin,

which causes diarrhea, was injected into human brain tumors implanted in mice. It not only shrank the

tumors, but none of the tumors reappeared.

How can a substance dangerous in the stomach not be dangerous to the brain cells? “What is important is the

amount of the toxin,” says Dr. Clifford Lingwood of the Hospital for Sick Children in Toronto. Just a little

bit of it won’t hurt you, but the more you’re exposed to the sicker you’ll get. The idea is to find a level

that is harmless to the animal as a whole, but deadly to the cancer cells. A study of baboons measured how

much verotoxin it would take to make an ape sick. Animals given small doses showed no side effects, nor did

the mice in Lingwood’s study.

Lingwood says that the verotoxin stops the growth of new blood vessels. “Tumor cells are particularly

susceptible,” he explains, because the tumors are marked by a specific glycolipid, a receptor that acts as a

gateway into the cell.

The verotoxin finds the glycolipids on tumors and the blood vessels that surround the tumor cells. It

attaches itself to the receptor and causes the cells to commit suicide. Verotoxins ignore normal, non-

cancerous brain cells, which don’t contain the receptor. With the toxin attacking both its outer membrane

and its food supply, the brain tumor shrivels almost immediately after treatment begins. In cancer cells in

Petri dishes, “You can see a significant difference in 90 minutes,” says Lingwood.

Lingwood’s results were reported in the June issue of the journal, Oncology Research.

—Martha Heil
Posted 7/19/1999

Answer the following questions:

1.     What experiments did the scientists perform?

2.     What hypothesis was tested?

3.     What data were collected?

4.     What were the conclusions of the study?

5.     Was the data collected sufficient to support the conclusions made?

6.     Was any important information about how the study was performed left out of the article? If so, what

information is missing?

7.     Is the title of this article an accurate statement of the study’s findings? Why or why not?

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