Posts Tagged ‘cancers’
New Genetic Circuit Detects Cancerous Cells and Forces Them To Commit Suicide
In principle, the circuit works like any other logic circuit: It analyzes multiple inputs and makes a decision. In this case, the circuit really consists of genes that can detect up to five cancer-specific molecules and their concentrations. When all five of those characteristics are present, the circuit makes a positive determination, and then it triggers cell death.
In a new study, researchers from MIT and ETH Zurich worked with HeLa cells, a prolific type of cervical cancer cell. They studied the cells’ microRNA, which regulates gene expression by destroying messenger RNA, the substance that brings the DNA blueprint to the rest of the cell. They eventually pinpointed one microRNA combo that was unique to HeLa cells. This is no small feat by itself — there are about 1,000 versions of miRNA in humans, . Each type of cancer has a unique miRNA profile.
Once they had the right combination, the researchers designed a synthetic gene which codes for a protein that promotes apoptosis, or . The special gene would turn on in the presence of miRNA levels that match the HeLa profile.
“The biocomputer combines the factors using logic operations such as AND and NOT, and only generates the required outcome, namely cell death, when the entire calculation with all the factors results in a logical TRUE value,” Yaakov Benenson, a professor of synthetic biology at ETH Zurich, said .
If the miRNA levels were too high or too low, the gene would not switch on, and the cell would not be killed. Healthy cells, which would also lack the HeLa profile, would be similarly left alone, the researchers said.
The next step would be to test this system in a living animal, but this will be difficult. Current methods use viruses or chemicals to bring foreign DNA inside cells, but these make permanent changes, which could have their own complications. So the method is still far from being usable for cancer treatment, researchers said.
Still, it is an important step toward building a single-cell-level diagnostic method, Benenson said. The research was published in today’s issue of Science.
[]
Cancers Are Newly Evolved Parasitic Species, Biologist Argues
Just as parasites do, cancer depends on its host for sustenance, which is why treatments that can be so effective. Thanks to this parasite-host relationship, cancer can grow however it wants, wherever it wants. Cancerous cells do not depend on other cells for survival, and they develop chromosome patterns that are distinct from their human hosts, according to , a molecular and cell biology professor at the University of California-Berkeley. As such, they’re novel species.
He argues that the prevailing theories of carcinogenesis, or cancer formation, are wrong. Rather than springing from a few genetic mutations that spur cells to grow at an uncontrolled pace, cancerous tumors grow from a disruption of entire chromosomes, he says. Chromosomes contain many genes, so mis-copies, breaks and omissions lead to tens of thousands of genetic changes. The result is a cell with completely new traits: A new phenotype.
Cancer as evolution in action, which represents a fundamental re-thinking of the disease, has been proposed before — evolutionary biologist Julian S. Huxley first described autonomously growing tumors as a new species back in 1956, according to a . But the prevailing view has long been that cancer is the result of genetic mutations.
Oncologists and pharmaceutical researchers are studying ways to find and block those mutations, aiming to turn off the switch that sparks carcinogenesis. But gene therapy has largely many meaningful results.
Duesberg argues, controversially, that it's misguided. Chromosomal mutation, called aneuploidy, is the cause instead, and it destabilizes chromosomal patterns. Some of the disrupted chromosomes are able to divide, seeding cancer. The result is a new chromosomal pattern that is distinct from our own. The Cal news office explains this in much greater detail.
Duesberg said he hopes this theory will spark new types of cancer diagnosis and treatment. Chromosomal tests could potentially pick out aneuploidy very early, before the damaged chromosomes have had a chance to divide, for instance. And new treatments could target the chromosomal disruptions, rather than knocking out or switching off genes.
Weaponized Salmonella Could Be Used to Fight Cancer in the Gut
Human trials are already under way at the University of Minnesota, where researchers have successfully tested salmonella-led tumor control in mice.
It could be useful in the fight against cancers in the gut area, like the liver, spleen and colon. That’s where salmonella infects people anyway, so arming it with some cancer-killing weapons could make it easier to attack cancer cells in those spots.
Researchers at U of M’s Masonic Cancer Center modified some salmonella to make it less potent, and they added a hormone that is used to fight cancer, called Interleukin 2. The hormone identifies tumor cells as a threat and triggers an immune response, and it’s used to treat skin melanomas and kidney cancer, according to the .
Yale Univeristy scientists reported last month that salmonella is able to , which allows it to inject itself into cells and take them over. Salmonella doped with IL-2 would exploit this ability, enabling the delivery of the cancer-fighting hormone into the affected areas.
The bacteria also likes to , as scientists have known for some time. Bacterial tumor reduction is actually a pretty old idea, according to a U of M — in a published report from 1860s Austria, a patient with a large tumor was placed in the same room as someone with a bad infection, and the infection eventually spread to the tumor, shrinking it. The infection also killed the cancer patient, however.
Although the bacteria is “weaponized” in this study, the salmonella itself is weakened, so a person wouldn’t get sick.
Patients would just have to drink a few ounces of salmonella-filled water and the bacteria would make its way through the body.
It might not replace traditional treatments like chemotherapy and radiation, but it wouldn’t have their nasty side effects. At the very least, it could be one more weapon in the arsenal against cancers in the gut.
[]
New ‘Breast on a Chip’ Will Allow Experimentation Into Nano-Treatment of Breast Cancer
The chip mimics the branching mammary duct system, where it is believed most breast cancers originate. It involves living cells lining a small 3-D replica of the tiniest portions of the mammary ducts, which are roughly the diameter of a human hair.
The duct system starts out as very small branches near the glands that produce milk, and the branches gradually combine into larger ducts before reaching the nipple. Doctors would like to inject fluids or particles through the nipple and into the branches, where they could wash out cells to examine them for cancer. (This sounds unpleasant, but it would be less invasive than a biopsy.) But fluid pressure in the ducts prevents any new fluids from getting through more than about 1/3 of the breast, according to a Purdue news release.
Instead, magnetized nanoparticles could float through the ducts’ natural fluid, controlled by a magnetic field instead of fluid pressure. They could float through the ducts, attach to cancer cells or deliver drugs into them, and then the magnetic field could be reversed to bring them back out.
This would have to be tested in a lab first, but typical breast cancer cell models are only 2-D. So Purdue professor James Leary used nanofabrication processes to create a tiny model of branching channels embedded in a rubberlike material. Then Sophie Lelièvre, who is a veterinary professor for some reason, coaxed mammary cells to grow in these synthetic ducts. The researchers can make changes to the cells or put tumor cells in the ducts to see whether nanoparticles recognize them, according to Purdue. The whole thing fits under a microscope.
The team still has to float some nanoparticles through the cell-coated ducts, and much more testing is necessary. But Lelièvre said she hopes the method could someday give breast cancer patients a new treatment option, and possibly save lives.
The U.S. Department of Defense funded the work.
[]
Tiny Buckyballs Could Put Fast-Spreading Cancer Cells into Suspended Animation
But their effect in normal cells may prove toxic for the body
This is a first-time finding for buckyballs, which are nanoparticles the size of a virus and consist of 60 carbon atoms each. But experts have been warning about the possible already found in many consumer products and types of research.
Toxicologists at the Los Alamos National Laboratory in New Mexico exposed human skin cells to several types of buckyballs. One tris configuration of buckyballs had three molecular branches coming off the main structural body in one hemisphere, a hexa configuration had six branches arranged in a symmetrical pattern, and the last was a plain buckyball.
The cells exposed to the tris buckyballs entered the suspended animation state, which could lead to problems with normal organ development and possibly disease in a living organism. The tris configuration may also interfere with the body's normal immune response against viruses.
That lead the researchers to suggest that any nanomaterials using buckyballs should use the non-toxic hexa configuration. But they're excited about possibly turning the tris buckyballs into a weapon for halting the spread of cancer cells or delaying the onset of Parkinson's or Alzheimer's in nerve cells.
It's all some heavy stuff to consider for such small nanoparticles. You can put yourself into a cheerier state of mind with this video by artist Alyce Santoro showing how to make a large buckyball replica out of ice cream cones.