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Biotech Medicine Science

Golden Nanocages To Put the Heat On Cancer Cells 97

ElectricSteve writes "Researchers have been searching for a highly targeted medical treatment that attacks cancer cells but leaves healthy tissue alone. The approach taken by scientists at Washington University in St. Louis is to use 'gold nanocages' that, when injected, selectively accumulate in tumors. When the tumors are later bathed in laser light, the surrounding tissue is barely warmed, but the nanocages convert light to heat, killing the malignant cells. ... Although the tumors took up enough gold nanocages to give them a black cast, only 6 percent of the injected particles accumulated at the tumor site. They would like that number to be closer to 40 percent so that fewer particles would have to be injected. They plan to attach tailor-made ligands to the nanocages that recognize and lock onto receptors on the surface of the tumor cells. ... The scientists at WUSTL have just received a five-year, $2.1M grant from the National Cancer Institute to continue their work with photothermal therapy." Note that Gizmag features a stupid Subscribe nag that covers your screen after about a minute; sounds like a job for NoScript. Last year we discussed somewhat similar research using titanium dioxide nanoparticles to target a particular kind of brain cancer.
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Golden Nanocages To Put the Heat On Cancer Cells

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  • by ChromeAeonium ( 1026952 ) on Tuesday March 16, 2010 @02:11AM (#31492360)

    Kinda funny really, but we still have people who think that same powdered silver [] (and to a lesser extent, gold []) is for internal use in curing pretty much everything.

  • by Anonymous Coward on Tuesday March 16, 2010 @02:20AM (#31492392)

    This is similar in principle to the Kanzius machine [] -- same idea, dope the cancer with some kind of radiation-sensitive material, then blast it. Kanzius wanted to use radio waves, but didn't know how to dope the cancer, but his oncologist knew a researcher at MD Anderson Cancer Center who was treating Nobel Laureate Rick Smalley [] -- one of the inventors of C-60, aka Buckminsterfullerene. Turns out that's a pretty good radiation target!

    Sounds like these guys are on to the same basic concept with lasers and gold. Targeted doping of cancer cells seems like a very promising concept.

  • by YayaY ( 837729 ) on Tuesday March 16, 2010 @03:05AM (#31492528) Homepage

    Please forget my ignorance. I'm canadian. []

  • Photodynamic therapy (Score:3, Informative)

    by paiute ( 550198 ) on Tuesday March 16, 2010 @07:40AM (#31493570)

    This is another form of photodynamic therapy []

    The problem has always to find a chemical which would accumulate in tumors and not in healthy tissures and would also respond to radiation by generating cell-killing chemicals. Not an easy couple of parameters to satisfy.

  • by SlashBugs ( 1339813 ) on Tuesday March 16, 2010 @08:32AM (#31493814)
    This is a cool variation on a basic idea that's been used before, and will make a great payload for cancer treatment. However, killing cancer cells is not all that difficult; rather targeting cancer cells is hard. It's all about the therapeutic index, i.e. the ratio of damage done to cancer cells against damage done to healthy tissue.

    Talking about cancer as "a disease" is a big misnomer; at best it's a huge family of diseases (really nice explanation in this comic []). Patterns do emerge -- certain tissues tend to have similar patterns of gene expression between people and therefore tend to give rise to similar cancers -- but each cancer that arises comes about in a different way, and evolves in response to different selective pressures within the body. The biggest of these pressures are fairly obvious like the need for neutrients (so "successful" cancers are the ones that evolve the ability to encourage blood vessels to grow around them) and evading the immune system. So, almost by definition, the outside of a cancer cell is forced to look as similar as possible to the outside or a healthy cell in the same tissue, to avoid detection.

    There are some exploitable internal differences. Most cancers (but by no means all, or even close to all) express hTERT, a gene responsible for repairing the telomeres, whose degradation would otherwise limit the cells' replication. So some researchers (including my former lab) are working on techniques to exploit that e.g. viruses that can only kill cells expressing hTERT. The downside is that some legitimate cells also express hTERT, most notably your stem cells (bone marrow, some other tissues).

    Another popular method is just targeting all cells that are highly metabolically active. Cancer cells tend to be working unusually hard (most cells in your body just sit there gently ticking over most of the time), so some cancer therapies target any cells that are burning through a lot of glucose (e.g. radiolabelled glucose is used as a source for imaging techniques like Positron Emission Tomography) or that are doing a lot of DNA replication as part of cell division. Again, though, this targets many cells in your body which are working this hard as a normal part of their programmes.

    So, yeah, this is a cool payload but targeting is the hard part. If we knew what ligands to tie these particles to for targeting and how to persuade these huge particles to move against a pressure gradient and through a dense, disorganised extra-cellular matrix, cancers wouldn't be half the problem that they actually are. We could be using targeted viruses (piece of piss to do if you know what you're targeting and the surrounding tissue isn't too dense), metal nanoparticles, targeted liposomes (little hollow balls of fat) containing toxins or toxin precursors, modified antibodies to alert the immune system to the cancer cells, etc, etc.

    Curing a cancer would be pretty easy: throw enough researchers and resources at one patient's specific tumour and we'll come up with a damn fine treatment. But curing all cancers -- different tumours arising from different tissues in different patients -- is seriously hard. We'll see fantastic advances in treating specific cancer types, but I seriously doubt that "a cure for cancer" is possible within our lifetimes. Although, heh, if you prove me wrong I won't be too upset :).

Always leave room to add an explanation if it doesn't work out.