Stealth nanoparticles lower drug-resistant tumors’ defenses
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Some of the most dangerous cancers are those that can outmaneuver the very drugs designed to defeat them, but researchers are now reporting a new Trojan-horse approach. In a preliminary study in the journal ACS Nano focusing on a type of breast cancer that is highly resistant to current therapies, they describe a way to sneak small particles into tumor cells, lower their defenses and attack them with drugs, potentially making the therapy much more effective.
Paula T. Hammond and colleagues at the Koch Institute of Integrative Cancer Research at MIT note that triple-negative breast cancer (TNBC) is an aggressive disease that is difficult to treat with standard-of-care therapy, and patients’ prognoses are poor. These cancer cells evade treatment by ramping up the production of certain proteins that protect tumors from chemotherapy drugs. Interfering with this process could give anticancer drugs a better chance at killing resistant tumors. Recent research into molecules called small interfering RNAs, or siRNAs, is opening doors into possible new treatments using this approach. These molecules can halt the production of particular proteins, so they are ideal candidates for dialing down the levels of protective proteins in tumors. But there are challenges to using siRNAs as part of a cancer therapy, so Hammond’s team set out to address them with novel molecular engineering approaches.
They designed a two-stage, “stealth” drug delivery system to attack TNBC cells in mice, often used as stand-ins for humans in research. They created “layer-by-layer” nanoparticles through assembly of components in a certain order around a nano-sized core.
Think twice before buying breast milk online: study
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Most of the breast milk sold over the Internet is contaminated with bacteria, a new study suggests.
Researchers tested 101 milk samples they bought on milk sharing websites. They found that almost three quarters probably weren’t safe for babies, especially preemies.
Those sites have thousands of ads from people selling breast milk, often new mothers who make more than their baby needs. The milk typically sells for $1 or $2 per ounce.
“If you buy milk on the Internet, you have no idea what you’re getting,” said Sarah Keim. She led the study at The Research Institute at Nationwide Children’s Hospital in Columbus, Ohio.
New idea for targeting the common cancer protein KRAS
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Patients with cancers driven by the protein KRAS, which are particularly hard to treat, may benefit from small molecules that attach to and disrupt the function of a KRAS-containing protein complex, according to results presented here at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics, held Oct. 19-23.
Mutant forms of the protein KRAS are found in approximately 30 percent of all cancers. They are responsible for many of the hallmarks of these cancers, and KRAS is, therefore, considered an important therapeutic target. However, attempts to develop clinically useful KRAS-targeted drugs have been unsuccessful.
“KRAS is a molecular switch,” said Michael Burns, a doctor of medicine and doctor of philosophy candidate at Vanderbilt School of Medicine in Nashville, Tenn. “In the ‘on’ state it transmits signals that drive cell growth and survival. In many cancers, KRAS is permanently in the on state, and it is a highly validated therapeutic target.
“KRAS switches from off to on most efficiently when it is attached to a protein called SOS,” explained Burns. “Each SOS protein attaches to two KRAS proteins, and we have identified a number of small molecules that bind to a particular part of SOS when it is in a complex with two KRAS proteins. These small molecules disrupt the function of the complex, ultimately causing inhibition of the signaling pathways downstream of KRAS that drive cell growth and survival. Although our data were generated in biochemical assays and cell lines, they suggest a potential way to therapeutically target KRAS, which has not been possible to date.”
