Enhanced laser thermal ablation for the in vitro treatment of liver cancer by specific delivery of multiwalled carbon nanotubes functionalized with human serum albumin.

The main goal of this investigation was to develop and test a new method of treatment for human hepatocellular carcinoma (HCC). We present a method of carbon nanotube-enhanced laser thermal ablation of HepG2 cells (human hepatocellular liver carcinoma cell line) based on a simple multiwalled carbon nanotube (MWCNT) carrier system, such as human serum albumin (HSA), and demonstrate its selective therapeutic efficacy compared with normal hepatocyte cells. Both HepG2 cells and hepatocytes were treated with HSA-MWCNTs at various concentrations and at various incubation times and further irradiated using a 2 W, 808 nm laser beam. Transmission electron, phase contrast, and confocal microscopy combined with immunochemical staining were used to demonstrate the selective internalization of HSA-MWCNTs via Gp60 receptors and the caveolin-mediated endocytosis inside HepG2 cells. The postirradiation apoptotic rate of HepG2 cells treated with HSA-MWCNTs ranged from 88.24% (for 50 mg/L) at 60 sec to 92.34% (for 50 mg/L) at 30 min. Significantly lower necrotic rates were obtained when human hepatocytes were treated with HSA-MWCNTs in a similar manner. Our results clearly show that HSA-MWCNTs selectively attach on the albondin (aka Gp60) receptor located on the HepG2 membrane, followed by an uptake through a caveolin-dependent endocytosis process. These unique results may represent a major step in liver cancer treatment using nanolocalized thermal ablation by laser heating.

Role of micro-RNAs in regulation of lentiviral latency and persistence.

Small interfering RNAs have been demonstrated to serve as a molecular defence against numerous retroviruses in plants and insects and, more recently, in primates. With the recent findings of micro-RNAs (miRNAs) that seem to play a pivotal role in the survival of the host, we have explored the role of miRNAs in lentiviral (LV) replication. We have previously hypothesized that, at least in the case of lentivirus infection, small interfering RNAs are involved in the inhibition of these types of viruses by the formation of intramolecular triplex formation (triplexes) between the polypurine tracks sequences of LV provirus and miRNAs and blocking the viral replication at the preintegration complex levels, placing these viruses into a suspended latency. Using several latently and chronically infected LV cell lines and human PBMCs from HIV-1-infected individuals, we show that perinuclear triplexes are formed in LV-infected cells. The number of triplexes decreased in cells with productive replication of LVs. Therefore, the degree of replication of HIV-1 and other LVs, both in the HIV-1 or other LV-infected cell lines and the HIV-1 infected PBMCs, inversely correlate with the number of cytoplasmic triplexes present in a particular cell. This correlation was further confirmed by the stimulation of PBMCs and LV-infected cell lines with appropriate mitogens. Treatment with Tagetin, a RNA polymerase III inhibitor, resulted in a significant decrease in triplexes and a dramatic increase in the LV replication. Our data suggest that triplex formation may be an important mechanism of LV latency mediated by endogenous miRNAs.