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RNA-Loaded Nanoparticles Fight Cancer
DirkDaring writes "It's been promised for years: that nanoparticles offer a treatment to many forms of cancer. Today, an important first step has been announced. In a new human trial, nanoparticles carrying RNA have successfully reached cancer cells and silenced the target gene. 'The researchers developed a nanoparticle carrying a molecular marker that binds to the surface of cancer cells, triggering the cells to absorb it. The siRNA carried within the particle was designed to silence a gene called ribonucleotide reductase M2 (RRM2), which regulates DNA synthesis and repair and is known to be an anticancer target. Because it was the first trial using targeted RNAi delivery for cancer, says Mark Davis, a professor of chemical engineering at Caltech and the study's lead author, "we wanted to choose a gene that was suspected to be hugely upregulated in a broad spectrum of cancers" in order to increase the likelihood of being able to observe the novel therapy's effect. The researchers analyzed biopsy samples from three melanoma patients in the trial who had received different doses of the therapy. They tracked the particles in the different samples, finding that the amounts they could see in the tumor cells correlated with the doses the patients received.'"
I wonder if this technique could be used for other diseases, e.g. arthritis?
Free Martian Whores!
Since the marker attaches to cancerous cells only, healthy ones should suffer no damage. Then again, I read the story above, so it's not like I'm specially insightful.
Cancer evolves and grows rapidly. Kill 90% of a tumor, and the 10% can grow to be a problem again.
The most interesting part here is not about directing damage, it is that this was a successful non-topical application of siRNAs. In most tests up to now, siRNAs have been injected directly into the target tissue. This study shows a delivery system that carries the siRNA specifically into targeted cells via the bloodstream. In the long run, this might be the key to target metastases however small they are and wherever they are.
Ubi solitudinem faciunt, pacem appellant.
Maybe I'm going out on a limb here, since I practically no medical schooling, but there have been suggestions by certain medical professionals (names elude me at the moment) that cancer cells could be the body's final (and potentially fatal) attempt to correct other, seemingly unrelated health issues. This would also explain why cancer can return after it has gone into remission.
If so, while this technique would stop the cancer cells from spreading, it may not address the cause of the cancer. I suppose we'll find out if/once the treatment becomes mainstream.
Gene specific targeting actually.
TV Personality: And how many people have you treated so far?
Dr. Alice Krippin: Well, we've had ten thousand and nine clinical trials in humans so far.
TV Personality: And how many are cancer-free?
Dr. Alice Krippin: Ten thousand and nine.
TV Personality: So you have actually cured cancer.
Dr. Alice Krippin: Yes, yes... yes, we have.
Cue destruction of humanity by albino gymnasts.
have been suggestions [..] certain medical professionals [..] could be
That are too many weasel words, and I raise a pseudo science alert! While I don't claim to know better, taking a potshot at conventional medicine with a very vague concept is not helpful.
Also, cancer cells are no longer within the normal parameters of human cells and mutate wildly, please suggest how they could be in any way helpful.
"Smoke 'em if you got 'em?"
"...I think the Microsoft hatred is a disease." - Linus Torvalds
See paper here http://www.nature.com/nature/journal/vaop/ncurrent/full/nature08956.html and article here http://www.nature.com/news/2010/100321/full/news.2010.138.html
Why do I keep seeing summaries that link to articles that are summaries of summaries of the original publication? Just link to the damn Nature article if that's the source.
Gold nanorods have also shown promise for the destruction of cancer cells. The really neat thing about them is that their absorption is tunable based on their size. In turn, they can be tuned to absorb in the near-infrared spectrum. The nanorods are then irradiated with near-infrared radiation, producing heat. This burns away cancer cells locally. There is still debate related to cell death caused by uptake of gold nanorods/nanoparticles.
In summary, we will hopefully be able to pew-pew-pew cancer to death with little damage to other cells. Yes, this whole post is constructed in order to use pew-pew-pew in a science related message.
Well, yes and no. You are absolutely right in that this isn't a permanent effect, in the sense that the DNA of the cancer cells is not altered at all. RNA interference is like putting a defender in the game to intercept a pass; if the defender leaves the field, the receiver will be open again. Translation of the ribonucleotide reductase gene will only be blocked as long as the interfering RNA is there to block the messenger RNA. However, ribonucleotide reductase is incredibly important; it's the enzyme that tears a hydroxyl group off of ribonucleotides and makes them deoxyribonucleotides. A cell cannot make DNA without it. The notion is that cancer cells being treated with RNAi will die during the course of treatment, with no way to replace them. If you get all the cancer, there is no way for it to "bounce back," and if you miss some, then at least progression has been seriously slowed.
On the point of receptors, that raises an interesting point. The nanoparticles used in this experiment target transferrin receptor, a cell surface receptor for the iron-carrying protein transferrin. Transferrin is highly upregulated in cancer cells because iron is required by many enzymes important to cell division (including ribonucleotide reductase, incidentally). Because it is so vital, cancer cells probably cannot just stop making transferrin. Developing a mutant form of transferrin that the nanoparticles cannot adhere to is a possibility, but there'd be a very narrow window of success (success from the cancer's POV). After all, cancer develops a transferrin receptor because it needs to get iron from transferrin- the same transferrin floating in your bloodstream your healthy cells uses. So whatever stealth transferrin receptor cancer cells come up to hide from nanoparticles still has to be compatible with real transferrin, or the cancer cells will be unable to divide.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."