Tag: cancer (page 1 of 4)

the problem with cancer cells

HeLa cells cancer research

HeLa cells, cancer cells originally isolated from Henerietta Lacks, are among the most widely used cell lines for scientific research

Cell lines are frequently used in cancer research studies. They are pretty easy to maintain and they grow fast. The cell lines give us insight into some of the cellular pathways involved in tumor biology. They are often used as early-stage screens for potential cancer therapeutics, even though scientists know that they do not exactly share the same biology as an actual tumor. Cancer cells grow rapidly and they generate many mutations in the process. In a few cycles, the cells that you have in culture are different genomically than the cells that you started with. But still, having some information on what cells maybe doing in a tumor is better than no information at all.

Now Derek Lowe calls attention to a new study in Nature, which points out a potential problem with these cell lines in culture. In this new paper, the researchers found that not only are cancer cells different from the tumor that they started from, but there can be many differences within a strains of any given cell line.  When they observed 27 strains of the MCF7 breast cancer line, the discovered rapid genetic diversification. They then looked at 13 additional cell lines and saw similar results. The genetic differences changed activation of gene expression, cell morphology and cell proliferation.

Derek Lowe sums up what this means for compound screening in cancer cell lines:

At least 75% of the compounds that showed strong inhibition of one MCF7 line were totally inactive against others. That’s going to confound experiments big-time, and this paper is a loud warning for people to be aware of this problem and to do something about it.

bacteria aid chemotherapy response

Bacteria

Image from Discover Magazine

In the latest edition of Science magazine, two papers describe how bacteria in the stomach and intestines can help improve chemotherapy outcomes – at least in mice.

In the first study, Iida et al. dosed a group of mice with antibiotics for a prolonged period before exposing them to cancer therapies. The antibiotic treatment eliminated their populations of gut microbes. Tumors in these mice did not shrink in response to the therapy as they did in the control group, which received no antibiotics. Similarly, mice brought up in a sterile environment also had showed no chemotherapeutic response. Mice brought up in sterile environments never develop diverse microbial populations since they don’t get exposed to them. Mice lacking the bacterial populations don’t show the production of a protein called tumor necrosis factor that generates the tumor killing response in the organism.

The researchers also found that when the chemotherapeutic drug oxaliplatin was administered to mice who were germ-free or given antibiotics, the cancer killing response was much weaker and ineffective when compared to the control.

The second group of researchers performed similar studies with a chemotherapy drug called cyclophosphamide, or CTX. CTX is used to treat breast cancers and some brain cancers and works by increasing the number of Th17/Th1 immune cells. As in the previously mentioned study, mice that were dosed with antibiotics or that were raised in sterile environments exhibited a weaker anti-tumor response to the CTX.

Results from both of  these studies indicate that microbes influence anti-tumor responses. So what does that mean for cancer patients? Dr. Zitvogel, who led one of the research teams, is taking considering the implications saying “We are going to be very careful about prescribing antibiotics during chemotherapy.” Dr. Trinchieri, who led another team, says that we should be cautious about extrapolating any results from mice to humans. He also suggests studies in healthy humans examining the effect of gut bacteria on immune cell production. His sentiment would likely be seconded by most scientists. As a matter of fact, Science magazine has another article in the same issue titled “When Mice Mislead”.

breath test for stomach cancer

Cancer breathalyzer

A breath test for cancer.

Researchers are reporting a new test for gastric cancer in the British Journal of Cancer (Abstract is free, subscription required for full article). In the study the researchers looked at 130 patients with different gastric conditions. Of the patients 37 had gastric cancer, 32 had ulcers and 61 had less serious complaints. As it turns out, the cancer causes an identify chemical identifier.  Patients diagnosed with cancer produced elevated levels of the following volatile organic compounds: 2-propenenitrile, 2-butoxy-ethanol, furfural, 6-methyl-5-hepten-2-one and isoprene. These levels can be detected by gas chromatography, but the researchers developed a special nanoparticle sensor that could detect these compounds at the parts per billion level. This study seems to bolster previous research where dogs were able to identify cancer patients with ~71% accuracy based on breath samples. It is also supported by a study where lung cancer was detected using a breathalyzer type test. But, since this was a small study these results will have to be confirmed using a larger sample.

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