Nanobubbles Deliver Targeted Cancer Drugs Using Ultrasound
A new targeted drug delivery method uses ultrasound to image tumors, while also releasing the drug from “nanobubbles” into the tumor.
Cancer drugs can be targeted to tumors by delivering them in packets of nanoparticles, then releasing them with ultrasound. But this approach can be difficult because it requires a way to image the tumor prior to treatment.
Natalya Rapoport, Ph.D., D.Sc., of the University of Utah in Salt Lake City and colleagues describe a new method of drug delivery that may address this problem. Nanobubbles filled with the chemotherapy drug doxorubicin were injected into mice. The bubbles accumulated in the tumors, where they combined to form larger “microbubbles.” When exposed to ultrasound, the bubbles generated echoes, which made it possible to image the tumor. The sound energy from the ultrasound popped the bubbles, releasing the drug. In mice treated with this method, the nanobubbles were more effective at blocking tumor growth than other nanoparticle delivery methods.
“Microbubble formulations have been developed for combining ultrasonic tumor imaging and ultrasound-enhanced chemotherapeutic treatment,” the authors write.
Contact: Natalya Rapoport, natasha.rapoport@m.cc.utah.edu, (801) 581-8990
Gene May Promote Resistance to Chemotherapy Drugs
A gene known as HDAC1 may be a good target for drugs to treat multidrug-resistant neuroblastoma, a cancer that develops in immature nerve cells and is prevalent in children.
Drug resistance could explain why about 50% of high-risk neuroblastoma patients die of the disease. Nino Keshelava, M.D., of Childrens Hospital Los Angeles and colleagues studied several human neuroblastoma cell lines to identify genes that cause drug resistance.
They found that HDAC1 was overexpressed in multidrug-resistant cells, compared with drug-sensitive cells. Blocking HDAC1 made the cells more sensitive to chemotherapy drugs that treat neuroblastoma.
“This gene is of particular interest because [HDAC] inhibitors are a relatively new class of cancer chemotherapeutic agents undergoing preclinical testing for clinical development in the treatment of drug-resistant neuroblastoma,” the authors write.
Contact: Steve Rutledge, director of communications, Childrens Hospital Los Angeles, srutledge@chla.usc.edu, (323) 361-4121
High Vitamin D Levels Are Associated with Reduced Colon Cancer Risk
A new study confirms an association between increased vitamin D levels and decreased risk of colon cancer.
Previous studies have shown that colon cancer mortality rates are lower in regions with greater sun exposure, which leads to vitamin D synthesis in the skin.
Kana Wu, M.D., Ph.D., of the Harvard School of Public Health in Boston and colleagues measured the levels of vitamin D in the blood plasma of 372 colorectal cancer patients and 739 controls. They used data from the Health Professionals Follow-up Study and the Nurses’ Health Study.
In the health professionals study, the researchers found an association between higher concentrations of vitamin D in patients’ plasma and reduced risk of colon cancer and colorectal cancer, though the latter link was not statistically significant. When combining data from both studies, the association held up for both colon and colorectal cancer.
“In conclusion, our data provide additional support for an inverse association between vitamin D and colorectal and in particular colon cancer risk,” the authors write.
Contact: Robin Herman, assistant dean of communications, Harvard School of Public Health, rherman@hsph.harvard.edu
Also in the July 10 JNCI:
- http://www.eurekalert.org/emb_releases/2007-07/jotn-sa070507.php
- http://www.eurekalert.org/emb_releases/2007-07/jotn-fn070507.php
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