Introduction
The ever-increasing development of nanoparticles with various physicochemical properties for different industrial applications has greatly enhanced human exposure to nanomaterials. This exposure can be deliberate, such as in applications where nanoparticles are used as imaging agents or drug carriers, and unintentional, e.g., through nanoparticles pollution of the environment by industrial production. The aim of the presented study was to assess the possible interference of silver nanoparticles (AgNPs, 20 nm, BSA coated) with the cellular signaling activated by the tumor necrosis factor (TNF, formerly known as TNFα) in HepG2 liver hepatocellular carcinoma cell line.
Methods
HepG2 cells were incubated with TNF or/and AgNPs for various time periods. Absorption of AgNPs was confirmed cytometrically using side-scattered light. Viability was assessed after 24 hours by neutral red uptake assay. Cell reproductive death was determined by clonogenicity test after 7-12 days. Expression of the genes associated with apoptosis and NF-kappaB signaling was analyzed by real-time PCR.
Results
During 24-hour incubation, the effect of TNF and AgNPs on viability of cells was additive. Over a longer incubation period (7-12 days), in the clonogenicity test, the effect of TNF and AgNPs on the cell survival was synergistic. Analysis of transcriptional response to TNF in the presence or absence of AgNPs revealed that the expression of TNFSF9 was enhanced in TNF and AgNPs treated cells compared to that observed after TNF alone. This effect was observed after treatment for both 6 and 24 h. AgNPs augmented also the expression of cytokines IL10, TNFSF15 and TNFSF8 but only after longer treatment (24h). On the contrary, the expression of BAG3 was augmented only after short treatment (6h).
Discussion
The presented results suggest that AgNPs may interfere with the cellular response to TNF and disrupt the cellular homeostasis contributing to the development of malignancies, such as cancer or autoimmune diseases at the level of the organism. Therefore, an extended study is needed to provide more information about the nature and specificity of the functional interactions between TNF and AgNPs in cells.
This work was supported by the grant 2014/13/D/NZ7/00286 from National Science Centre, Poland.
Nanomedicine for cancer diagnosis & therapy , Toxicology and risk assessment of nanomedicine systems
