Evan S. Krystofiak

Elimination of tumor cells using folate receptor targeting by antibody-conjugated, gold-coated magnetite nanoparticles in a murine breast cancer model

Background. The chemotherapeutic treatment of cancer suffers from poor specificity for targeting the tumor cells and often results in adverse effects such as systemic toxicity, damage to nontarget tissues, and development of drug-resistant tumors in patients. Increasingly, drug nanocarriers have been explored as a way of lessening or overcoming these problems. In this study, antibodyconjugated Au-coatedmagnetite nanoparticles, in conjunction with inductive heating produced by exposure to an oscillating magnetic field (OMF), were evaluated for their effects on the viability of tumor cells in a murine model of breast cancer. Treatment effects were evaluated by light microscopy and SEM. Results. 4T1 mammary epithelial carcinoma cells overexpressing the folate receptor were targeted with an anti-folate receptor primary antibody, followed by labeling with secondary antibody-conjugated Aucoated magnetite nanoparticles. In the absence of OMF exposure, nanoparticle labeling had no effect on 4T1 cell viability. However, following OMF treatment, many of the labeled 4T1 cells showed extensive membrane damage by SEM analysis, and dramatically reduced viability as assessed using a live/dead staining assay. Conclusions. These results demonstrate that Au-coated magnetite targeted to tumor cells through binding to an overexpressed surface receptor, in the presence of an OMF, can lead to tumor cell death.

Low-dose gold nanoparticles exert subtle endocrine-modulating effects on the ovarian steroidogenic pathway ex vivo independent of oxidative stress

Abstract Gold nanoparticles (GNPs) have gained considerable attention for application in science and industry. However, the untoward effects of such particles on female fertility remain unclear. The objectives of this study were to (1) examine the effects of 10-nm GNPs on progesterone and estradiol-17β accumulation by rat ovaries ex vivo and (2) to identify the locus/loci whereby GNPs modulate steroidogenesis via multiple-reference gene quantitative real-time RT-PCR. Regression analyses indicated a positive relationship between both Star (p < 0.05, r2 = 0.278) and Cyp11a1 (p < 0.001, r2 = 0.366) expression and P4 accumulation upon exposure to 1.43 × 106 GNPs/mL. Additional analyses showed that E2 accumulation was positively associated with Hsd3b1 (p < 0.05, r2 = 0.181) and Cyp17a1 (p < 0.01, r2 = 0.301) expression upon exposure to 1.43 × 13 and 1.43 × 109 GNPs/mL, respectively. These results suggest a subtle treatment-dependent impact of low-dose GNPs on the relationship between progesterone or estradiol-17β and specific steroidogenic target genes, independent of oxidative stress or inhibin.

Probing the Molecular Basis for the Lateral Flexibility of Tight Junction Strands

Tight junctions (TJ) form selective ion permeable barriers in epithelial and endothelial tissues that are essential for many physiological processes. These barriers consist of a network of sealing strands between adjacent cells primarily composed of linear claudin oligomers. Strand formation requires coordinated claudin interactions within the same membrane (cis) and interactions between monomers from adjoining cells (trans). The recently reported x-ray crystal structure of claudin-15 [1] has provided a structural basis for modeling TJ strands, leading to a proposal of a linear multimeric strand model [2] largely based on a cis interface (X-1) observed in the crystal packing (Fig.1A). Claudin strands are dynamic and able to maintain their barrier function during cell movements and large scale tissue rearrangements. Here we examined lateral bending and flexibility of claudin strands and we propose an alternative cis interaction.