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

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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.

NaD1 caused blebbing followed by lysis when introduced to human cancer cells. In other words, they developed bulges and then burst in the presence of this protein. There is unlikely to be a more satisfying experiment than one that results in the explosion of tumour cells.

Ligands in a cationic grip

Using a number of techniques including the X ray crystallography beam at the Synchrotron in Melbourne, they were able to describe the structure of the active component, which only worked when bound to lipids that came from the membrane of the target cell called PIP2. The final NaD1:PIP2 complex contained 14 copies of NAD1 bound to 14 copies of PIP2 in a unique ‘cationic grip’ configuration. The final complex was arch shaped with unusual fibrillar structures.

Written By: Susan Lawler
continue to source article at livescience.com

6 COMMENTS

  1. It sounds like there could be another beautiful use for these beautifully perfumed ornamental species of tobacco plant.
    Mine (Nicotiana affinis) are still in trays in my poly-tunnel greenhouse, but will shortly be perfuming the garden next to my driveway.

  2. That’s Ironic – but it seems to happen quite often in nature …I thought that cigarette smoking cancers were caused more by the horrid carcinogenic additives in the ciggies and not simply just the tobacco ?

  3. 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.

    Blebbing is my new favourite scientific word. :-)

  4. Blebbing is primarily for apoptotic cells to package in vesicles harmful substances that would do damage to neighbor cells in released during apoptosis.

    It certainly signals apoptosis and lysis.

  5. The problem with the phrase “cure for cancer” is there are over 200 diseases called “cancers”, and they don’t actually have very much in common, so we shouldn’t expect any one chemical to cure more than a small percentage of them. And when Lawler says, “This raises the prospect of the deepest kind of irony: tobacco grown to produce drugs used to treat cancers caused by tobacco”, that misses the question of whether this chemical could treat the exact same cancers that smoking causes. The article often talks about this chemical affecting “cancer cells”, but occasionally admits it has specific cancers in mind, and lung cancer isn’t one of them!

    Which cancers does the original study say can be treated? That was hard to discover; this piece links not to the study, but to another journalist’s coverage of it that in turn doesn’t link to the study. It took a fair amount of Google Scholar sleuthing to track it down. (I think all sciences should have something like the ArXiv.) It’s readable here: http://elifesciences.org/content/3/e01808.abstract As far as I can tell they’ve only analysed the few cancer types Lawler names. So why assume it works on lung cancers?

    Suppose for the sake of argument that NaD1 is ultimately useful for treating one or more human cancers. Lawler envisages a world in which fields of tobacco plants are grown to harvest NaD1. That’s not what the study suggests. That’s not what any reasonable scientist would suggest. Just put the NaD1 gene in a plasmid in a bacterium, then harvest the chemical in vats. That’s how we produce insulin.

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