doi:10.1038/nindia.2015.13 Published online 29 January 2015
How does one stop the runaway growth of cancer cells that defy anticancer drugs and radiation therapy? An Indian research team has found a way to stifle the growth of drug- and radiation-resistant cancer cells. They have developed graphene nanoparticles that can convert low radiofrequency powers to heat which annihilates such chronic myeloid leukaemia cells1.
“This combination of graphene nanoparticles and radiofrequency power is a promising cancer therapy as it offers minimally invasive treatment without the need of other therapeutic aids,” says first author Abhilash Sasidharan from Amrita Centre for Nanoscience and Molecular Medicine (ACNSMM), Kerala and now a post-doctoral fellow at the US-based Kansas State University. The therapy could potentially be used to selectively kill other types of drug-resistant cancer cells, he told Nature India.
Due to rise in drug- and radiation-resistant cancer cases, scientists have been trying to develop alternative anticancer therapies. They had synthesized carbon nanotubes and gold nanoparticles able to convert radio waves and near-infrared light to heat that killed cancer cells. But these nanoparticles generated heat that only killed malignant tumours smaller than 5 cm.
For larger tumours that could spread to multiple organs, Sasidharan along with ACNSMM director Shantikumar Nair and senior scientist Manzoor Koyakutty set out to probe the heat-generating potential of surface-modified graphene nanoparticles by exposing them to low radiofrequency powers. The team found that when exposed to low radiofrequency powers (10-50 watts) for 5 minutes, graphene showed higher thermal responses than those of single-walled carbon nanotubes and gold nanoparticles.
“These higher thermal responses of graphene may be attributed to high electron density on the graphene surface which, in turn, leads to high current densities, resulting in enhanced heat production,” Koyakutty explains.
The scientists then investigated whether these graphene nanoparticles could kill drug- and radiation-resistant cancer cells by converting low radiofrequency powers to heat. They attached the graphene nanoparticles with transferrin, an iron-transport protein. This protein binds to receptors which are highly expressed on the surface of drug-resistant cancer cells. Next, they exposed graphene-treated drug- and radiation-resistant cancer cells of chronic myeloid leukaemia to radiofrequency power of 50 watts for 5 minutes. Sophisticated imaging techniques revealed that graphene treatment followed by exposure to radiofrequency power triggered controlled death of the cancer cells.
In a separate animal study, the team had earlier shown that similar graphene nanoparticles are biodegradable and not-toxic to living cells2. “These results indicate that the combination of graphene nanoparticles and radiofrequency power could lead to effective cancer therapy for combating drug- and radiation-resistant cancers,” Koyakutty says.
Asifkhan Shanavas from the Institute of Nano Science and Technology, Punjab says the therapy precisely targets cancer cells of chronic myeloid leukaemia and also enhances the efficacy of radiation therapy, an existing cancer treatment. The graphene nanoparticles’ ability to kill tough cancer cells is encouraging since treating cancers with small drug molecules always results in the emergence of new drug-resistant mechanisms, he adds.
1. Sashidharan, A. et al. Radiofrequency ablation of drug-resistant cancer cells using molecularly targeted carboxyl-functionalized biodegradable graphene. Adv. Health. Mat.(2015) doi:10.1002/adhm.201400670