Wednesday, May 21, 2014

Tobacco Plants May Contain Cure for Cancer, a New Twist in Protein–Lipid Interactions

Ornamental tobacco plant, medicine 

Nicotiana alata, the ornamental tobacco plant, has a secret weapon in its flowers: a protein that bursts human cancer cells. 

Scientists at La Trobe University published a study this week about a protein found in the flowers of ornamental tobacco plant that targets human cancer cells and destroys them. This raises the prospect of the deepest kind of irony: tobacco grown to produce drugs used to treat cancers caused by tobacco.

Mark Hulett, Marc Kvansakul and others from the Biochemistry Department used a range of techniques to examine the structure and function of a protein called NaD1. This protein is a type of defensin, a molecule that protects the plant from fungal infections. Why it also works on mammalian cancer cells is unknown, but is probably related to similarities of their cell membranes, where the action in this story takes place. 

Of blebbing and lysis

In addition to testing the action of NaD1 against various fungi including yeast, the researchers tested its action on human cell lines known to come from lymphoma, cervical and prostate cancer. The action of interest was the disruption in cell membranes, which was measured in a variety of ways.

The leakage of ATP (a common molecule) was shown to happen within minutes of the introduction of NadD1 to lymphoma cells. Cervical cancers cells showed an increase in the uptake of a dye known as propidium iodide, demonstrating a breach of their cell membranes.

More dramatically, live confocal laser scanning microscopy was used to produce films showing cancer cells change shape in the presence of NaD1. Irregular shaped bulges in cells are known as blebs. Blebbing is like blowing up little balloons on the edges of cells, which often precede cell death. When membranes are broken, the contents of the cell are released in a process known as cell lysis.

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