Nanoparticles for cancer
doi:10.1038/nindia.2012.12 Published online 27 January 2012
New research has shown that autophagy, a cellular process that aids cell growth by removing foreign material, could be used to kill cancer cells. The study involved using specially synthesized magnetic nanoparticles that can exploit the potential of autophagy to kill lung cancer cells, thereby opening up a new therapeutic option for cancer.
Autophagy uses enzyme-secreting lysosomes — cellular organelles — to break down foreign material and even kill bacteria. Recent studies have shown that nanomaterials such as quantum dots could trigger autophagy in cancer cells. However, no studies have yet explored the therapeutic potential of autophagy in cancer.
The researchers added citric acid to ferric nitrate solution to form a gel under a magnetic stirrer. They dried the gel to yield magnetic iron oxide nanoparticles and exposed the cancer cells to increasing concentrations of nanoparticles.
Nanoparticle concentrations of more than 25 mg ml–1 caused an increase in cell death compared with the nanoparticles' normal effects on human lung fibroblast cells. Loss of mitochondrial membrane potential (MMP) and depletion of adenosine triphosphate (ATP) are signs of necrosis, a type of cell death. The researchers observed a significant loss of MMP and ATP in cancer cells exposed to high concentrations of nanoparticles.
In addition, the researchers also identified increased levels of several marker proteins of autophagy, such as the microtubule-associated protein light chain 3-II and adenosine monophosphate (AMP)-activated protein kinase, which signalled the onset of autophagy in cancer cells. This accelerated the generation of reactive oxygen species, leading to the death of the cancer cells.
"Although autophagy plays a pro-survival role in cancer cells, it can also promote cancer cell death, unveiling a new aspect of cancer therapy using iron oxide nanoparticles," says lead researcher Iqbal Ahmad.
The authors of this research are from: Fibre Toxicology Division, and Electron Microscopy Facility, CSIR-Indian Institute of Toxicology Research, Lucknow, India Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Eng. & Tech., Aligarh Muslim University, Aligarh, India.