Developmental exposure to silver nanoparticles leads to long term gut dysbiosis and neurobehavioral alterations

Due to their antimicrobial properties, silver nanoparticles (AgNPs) are used in a wide range of consumer products that includes topical wound dressings, coatings for biomedical devices, and food-packaging to extend the shelf-life. Despite their beneficial antimicrobial effects, developmental exposure to such AgNPs may lead to gut dysbiosis and long-term health consequences in exposed offspring. AgNPs can cross the placenta and blood–brain-barrier to translocate in the brain of offspring. The underlying hypothesis tested in the current study was that developmental exposure of male and female mice to AgNPs disrupts the microbiome–gut–brain axis. To examine for such effects, C57BL6 female mice were exposed orally to AgNPs at a dose of 3 mg/kg BW or vehicle control 2 weeks prior to breeding and throughout gestation. Male and female offspring were tested in various mazes that measure different behavioral domains, and the gut microbial profiles were surveyed from 30 through 120 days of age. Our study results suggest that developmental exposure results in increased likelihood of engaging in repetitive behaviors and reductions in resident microglial cells. Echo-MRI results indicate increased body fat in offspring exposed to AgNPs exhibit. Coprobacillus spp., Mucispirillum spp., and Bifidobacterium spp. were reduced, while Prevotella spp., Bacillus spp., Planococcaceae, Staphylococcus spp., Enterococcus spp., and Ruminococcus spp. were increased in those developmentally exposed to NPs. These bacterial changes were linked to behavioral and metabolic alterations. In conclusion, developmental exposure of AgNPs results in long term gut dysbiosis, body fat increase and neurobehavioral alterations in offspring.

Magnetic Iron Nanocubes Effectively Capture Epithelial and Mesenchymal Cancer Cells

Current methods for capturing circulating tumor cells (CTCs) are based on the overexpression of cytokeratin (CK) or epithelial cell-adhesion molecule (EpCAM) on cancer cells. However, during the process of metastasis, tumor cells undergo epithelial-to-mesenchymal transition (EMT) that can lead to the loss of CK/EpCAM expression. Therefore, it is vital to develop a capturing technique independent of CK/EpCAM expression on the cancer cell. To develop this technique, it is important to identify common secondary oncogenic markers overexpressed on tumor cells before and after EMT. We analyzed the biomarker expression levels in tumor cells, before and after EMT, and found two common proteins-human epidermal growth factor receptor 2 (Her2) and epidermal growth factor receptor (EGFR) whose levels remained unaffected. So, we synthesized immunomagnetic iron nanocubes covalently conjugated with antibodies of Her2 or EGFR to capture cancer cells irrespective of the EMT status. The nanocubes showed high specificity (6-9-fold) in isolating the cancer cells of interest from a mixture of cells spiked in serum. We characterized the captured cells for identifying their EMT status. Thus, we believe the results presented here would help in the development of novel strategies for capturing both primary and metastatic cancer cells from patients' blood to develop an effective treatment plan.

Silencing AXL by covalent siRNA-gelatin-antibody nanoconjugate inactivates mTOR/EMT pathway and stimulates p53 for TKI sensitization in NSCLC

Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality with the 5-year survival rate at a dismal 16% for the past 40 years. Drug resistance is a major obstacle to achieving long-term patient survival. Identifying and validating molecular biomarkers responsible for resistance and thereby adopting multi-directional therapy is necessary to improve the survival rate. Previous studies indicated ~20% of tyrosine kinase inhibitor (TKI) resistant NSCLC patients overexpress AXL with increase in EMT and decrease in p53 expression. To overcome the resistance, we designed gelatin nanoparticles covalently conjugated with EGFR targeting antibody and siRNA (GAbsiAXL). GAbsiAXL efficiently silences AXL, decreases mTOR and EMT signaling with concomitant increase in p53 expression. Because of the molecular changes, the AXL silencing sensitizes the cells to TKI. Our results show AXL overexpression has an important role in driving TKI resistance through close association with energy-dependent mitochondrial pathways.

Abstract 4171: Combined AXL/FN14 inhibition sensitize drug-resistant NSCLC in vitro and in vivo

Lung cancer is the number one cause of cancer-related deaths in both men and women with a median survival time of 8-10 months’ post treatment. Non Small Cell Lung Cancer (NSCLC) accounts for 80% of the lung cancers and the treatment plan is determined based on the active mutations (EGFR, ALK/ROS, and KRAS) present in the tumor. Patients bearing EGFR mutation initially respond to targeted tyrosine kinase inhibitor (TKI) therapy and after 10-14 months of treatment acquire TKI resistance. Consequently, the median PFS for NSCLC patients with EGFR mutation is only 9.5 months. The reason for this acquired drug resistance is not yet fully understood. Recent studies have reported oncogenes such as AXL could be responsible for TKI resistance. Therefore, understanding the mechanism of drug resistance is key in developing a solution to overcome the problem. For this study, we first examined the resistance mechanism and developed a biodegradable targeted nanoparticle based solution to systematically investigate the role of AXL in resistant NSCLC cell lines. In this study we (1) downregulated AXL using siRNA and separately (2) knocked out the AXL gene using crRNA (CRISPR) and treated with TKI. Our results show that AXL is responsible for activation of several EMT related proteins and upregulation of mTOR pathway. We believe the upregulation of these proteins is essential for cancer cells to switch pathways for proliferation and regulating miRNAs linked to mutations. Our results further confirm that AXL is responsible for regulating MMP-2 that is associated with cell invasion. Based on data from multiple cell lines such as H820 and A549, we demonstrate that AXL upregulation is responsible for resistance independent of EGFR activating mutations. The elucidated pathway for drug resistance was further confirmed in cell lines generated by knocking-out the AXL gene. Interpretation for AXL signaling and drug resensitization was confirmed by Western blotting, Zymography, Invasion & Migration assay, Apoptosis assay and MTT toxicity assay. We performed mRNA and miRNA analysis using qRT-PCR to understand gene expression post treatment. During the process of our investigation, we found that NSCLC cells undergo further survival cross talk with other biomarkers. Indeed, we report the first experimental evidence of a survival cross talk between AXL and FN14, a wound healing gene, that enhance cell survival post treatment. Down regulation of both AXL and FN14 dramatically reduced the IC50 of TKI. Based on the mechanism, we designed a gelatin nanoparticle that can carry both AXL and FN14 to deliver it in the tumor cell. The nanoparticle is targeted to tumor using EGFR-antibody and releases the silencing RNA within cytoplasm. We further demonstrated that dual-inhibition of AXL and FN14 in A549 mice xenografts showed tumor reduction compared to controls. In conclusion, inhibition of AXL and FN14 can maximize therapeutic response of TKI, wherein AXL is upregulated before or during drug treatment.

Citation Format: Dhananjay Suresh, Ajit Zambre, Soumavo Mukherjee, Shreya Ghoshdastidar, Jennifer L. Schnabel, Sarah Chapman, W. Matthew Leevy, Anandhi Upendran, Raghuraman Kannan. Combined AXL/FN14 inhibition sensitize drug-resistant NSCLC in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4171. doi:10.1158/1538-7445.AM2017-4171