Naphthalene in mothballs and para-dichlorobenzene, or PDCB, found in some air fresheners, were shown to block enzymes that initiate programmed cell death, or apoptosis, said Associate Professor Ding Xue of CU-Boulder's molecular, cellular and developmental biology department. Apoptosis is a normal function of certain cell groups that acts as a "brake" to prevent unchecked cellular proliferation similar to the process that triggers the formation of cancerous tumors, said Xue.
While naphthalene and PDCB have been shown to cause cancer in rodents and are classified by the National Toxicology Program and the International Association for Research on Carcinogens as potential human carcinogens, their biochemistry has not been well understood, said Xue. But using a common, eyelash-sized worm known as C. elegans, the research team has shown that naphthalene can cause the inactivation of a group of enzymes known as caspases -- which control cell suicide -- by oxidizing them.
The study appears in the June issue of Nature Chemical Biology. It was authored by Xue and David Kokel of CU-Boulder's MCD biology department and Yehua Li and Jun Qin of the Baylor College of Medicine in Houston.
"This study shows why mothballs and some air freshener products may be harmful to humans," said Xue. "And, for the first time, we have developed a systematic way to screen virtually any potential cancer-causing chemical that may affect humans using these nematodes as animal models."
In the study, caspase enzymes from both nematodes and from humans were blocked after exposure to naphthalene, indicating a "comparable pharmacology" between worms and humans, said Xue.
Understanding how carcinogenic compounds can trigger tumor growth is important for federal regulatory agencies that deal with human exposure to hazardous chemicals, said Xue. More than 1 million pounds of naphthalene and PDCB are used by consumers annually, according to the study.
The nematodes were grown on a culture medium coated with a soybean-based oil that is harmless to the worms but which can dissolve naphthalene and PDCBs, said Xue. When the chemicals were added to the culture, they deactivated the caspases, resulting in the survival of "extra" cells in the tiny worms that normally would have been eliminated by apoptosis, said Xue.
Apoptosis is an essential process in animal development and occurs in many tissues, said Xue. In amphibians it rids frogs of tails as they develop from larvae to adults, and in humans it removes cells that make up "webbing" tissue between the fingers and toes of embryos during development, he said.
"Apoptosis serves as a checking mechanism to ensure that the right amount of cells are generated in the body," Xue said. In Alzheimer's disease and Parkinson's disease, too much apoptosis is occurring, while in cancer and autoimmune disorders, too little apoptosis is occurring, he said.
Popular with scientists in research labs around the world, C. elegans worms have essentially the same basic biological processes as humans even though their average lifespan is less than three days, he said. Xue's team currently is using C. elegans as an animal model "bioassay" to test common industrial chemicals like biphenyl, toluene and benzene that are suspected to be carcinogens.
"The power of C. elegans' molecular genetics, in combination with the possibility of carrying out large-scale chemical screens in this organism, makes C. elegans an attractive and economical animal model for both toxicological studies and drug screens," the researchers wrote in Nature Chemical Biology.
"Bioassays involving lab rats can take two years to complete," he said. "But we can do the same kind of bioassays with nematodes in two weeks, and we can do them at our lab benches instead of animal care facilities."
Ding Xue | EurekAlert!
Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory
How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy