Tissue-Penetrating Light Releases Chemotherapy inside Cancer Cells

A light-activated drug delivery system is particularly promising, because it can accomplish spatial and temporal control of drug release.

Drs. Jeffrey Zink, professor of chemistry and biochemistry, and Fuyu Tamanoi, professor of microbiology, immunology, and molecular genetics, and colleagues, from the University of California, Los Angeles’ (UCLA) Jonsson Comprehensive Cancer Center (JCCC; Los Angeles, USA) published their findings February 20, 2014, in the journal Small.

Finding ways to deliver and release anticancer drugs in a controlled way that only targets the tumor can greatly decrease the amount of side effects from treatment, and greatly increase the cancer-killing efficacy of the drugs. The challenges of treating cancer frequently comes from the difficulty of getting anticancer chemotherapy drugs to tumor cells without damaging healthy tissue in the process. Many cancer patients experience treatment side effects that are the result of drug exposure to healthy tissues.

A major challenge in the development of light-activated drug delivery is to design a system that can respond to tissue-penetrating light. Drs. Tamanoi and Zink joined their diverse teams and collaborated with Dr. Jean-Olivier Durand at University of Montpellier, France to develop a new type of microscopic particles (nanoparticles) that can absorb energy from tissue-penetrating light that releases pharmaceutical agents in cancer cells.

These new nanoparticles are armed with specially designed nanovalves that can control release of anticancer drugs from thousands of pores, or tiny tubes, which hold molecules of chemotherapy drugs within them. The ends of the pores are blocked with capping molecules that hold the drug in similar to a cork in a bottle. The nanovalves contain special molecules that respond to the energy from two-photon light exposure, which opens the pores and releases the anticancer drugs. The performance of the nanoparticles was demonstrated in the laboratory using human breast cancer cells.

Because the effective depth range of the two-photon laser in the infrared red wavelength can reach 4 cm from the skin surface, this delivery system is best suited for tumors that can be reached within that range, which possibly include stomach breast, colon, and ovarian cancers.

Another facet of the nanoparticles is that they are fluorescent and therefore can be monitored in the body with molecular imaging techniques. This allows the researchers to track the progress of the nanoparticle into the cancer cell to safeguard that it is in its target before light activation. This ability to track a targeted therapy to its target has been called “theranostics” in the scientific nomenclature. “We have a wonderful collaboration,” said Dr. Zink. “When the JCCC brings together totally diverse fields, in this case a physical chemist and a cell signaling scientist, we can do things that neither one could do alone.”

“Our collaboration with scientists at Charles Gerhardt Institute was important to the success of this two-photon activated technique,” said Dr. Tamanoi. “It provides controls over drug delivery to allow local treatment that dramatically reduces side effects.”

Related Links:
University of California, Los Angeles’ Jonsson Comprehensive Cancer Center