Enhancing Antibiotic Activity Using Nanomaterial-Antibiotic Conjugates

We demonstrate that streptomycin conjugated on silica nanoparticles (SNP-Str) can be used to effectively target streptomycin-resistant Escherichia coli (E. coli) bacteria by lowering the minimum inhibitory concentration (MIC) of streptomycin up to 2 log folds. Silica nanoparticles were synthesized with an average diameter of 80, 50 and 30 nm, respectively. Streptomycin was then covalently conjugated to SNP using efficient photocoupling chemistry. The MIC for free streptomycin sulfate was recorded as a high 2.0 mg/mL for an engineered Strr mutant E. coli ORN 208. Conjugating the streptomycin to SNP resulted in the decrease in MIC to 161 μg/mL, 63 μg/mL, and 19 μg/mL for SNP of 80, 50 and 30 nm, respectively. In this poster, the synthesis, characterization, and evaluation of SNP-Str will be presented and discussed

DHODH modulates transcriptional elongation in the neural crest and melanoma

Melanoma is a tumour of transformed melanocytes, which are originally derived from the embryonic neural crest. It is unknown to what extent the programs that regulate neural crest development interact with mutations in the BRAF oncogene, which is the most commonly mutated gene in human melanoma1. We have used zebrafish embryos to identify the initiating transcriptional events that occur on activation of human BRAF(V600E) (which encodes an amino acid substitution mutant of BRAF) in the neural crest lineage. Zebrafish embryos that are transgenic for mitfa:BRAF(V600E) and lack p53 (also known as tp53) have a gene signature that is enriched for markers of multipotent neural crest cells, and neural crest progenitors from these embryos fail to terminally differentiate. To determine whether these early transcriptional events are important for melanoma pathogenesis, we performed a chemical genetic screen to identify small-molecule suppressors of the neural crest lineage, which were then tested for their effects on melanoma. One class of compound, inhibitors of dihydroorotate dehydrogenase (DHODH), for example leflunomide, led to an almost complete abrogation of neural crest development in zebrafish and to a reduction in the self-renewal of mammalian neural crest stem cells. Leflunomide exerts these effects by inhibiting the transcriptional elongation of genes that are required for neural crest development and melanoma growth. When used alone or in combination with a specific inhibitor of the BRAF(V600E) oncogene, DHODH inhibition led to a marked decrease in melanoma growth both in vitro and in mouse xenograft studies. Taken together, these studies highlight developmental pathways in neural crest cells that have a direct bearing on melanoma formation

Precision medicine driven by cancer systems biology

Molecular insights from genome and systems biology are influencing how cancer is diagnosed and treated. We critically evaluate big data challenges in precision medicine. The melanoma research community has identified distinct subtypes involving chronic sun-induced damage and the mitogen-activated protein kinase driver pathway. In addition, despite low mutation burden, non-genomic mitogen-activated protein kinase melanoma drivers are found in membrane receptors, metabolism, or epigenetic signaling with the ability to bypass central mitogen-activated protein kinase molecules and activating a similar program of mitogenic effectors. Mutation hotspots, structural modeling, UV signature, and genomic as well as non-genomic mechanisms of disease initiation and progression are taken into consideration to identify resistance mutations and novel drug targets. A comprehensive precision medicine profile of a malignant melanoma patient illustrates future rational drug targeting strategies. Network analysis emphasizes an important role of epigenetic and metabolic master regulators in oncogenesis. Co-occurrence of driver mutations in signaling, metabolic, and epigenetic factors highlights how cumulative alterations of our genomes and epigenomes progressively lead to uncontrolled cell proliferation. Precision insights have the ability to identify independent molecular pathways suitable for drug targeting. Synergistic treatment combinations of orthogonal modalities including immunotherapy, mitogen-activated protein kinase inhibitors, epigenetic inhibitors, and metabolic inhibitors have the potential to overcome immune evasion, side effects, and drug resistance

B Cell Translocation Gene 2 Enhances Susceptibility of HeLa Cells to Doxorubicin-induced Oxidative Damage*

BTG2/TIS21/PC3 (B cell translocation gene 2) has been known as a p53 target gene and functions as a tumor suppressor in carcinogenesis of thymus, prostate, kidney, and liver. Although it has been known that the expression of BTG2/TIS21/PC3 is induced during chemotherapy-mediated apoptosis in cancer cells, a role of BTG2/TIS21/PC3 in cell death remains to be elucidated. In this study, the mechanism and role of BTG2 involved in the enhancement of doxorubicin (DOXO)-induced cell death were examined. Treatment of HeLa cells with DOXO revealed apoptotic phenomena, such as chromatin condensation and cleavage of poly(ADP-ribose) polymerase and lamin A/C with concomitant increase of BTG2/TIS21/PC3 expression. Employing infections of Ad-TIS21 virus and lentivirus with short hairpin RNA to BTG2, the effect of BTG2/TIS21/PC3 on the DOXO-induced apoptosis of HeLa cells and liver cancer cells was evaluated. Not only short hairpin RNA-BTG2 but also N-acetyl-l-cysteine significantly reduced the DOXO-induced HeLa cell death and generation of H2O2. Moreover, forced expression of BTG2/TIS21/PC3 using adenoviral vector augmented DOXO-induced cancer cell death concomitantly with increase of manganese-superoxide dismutase but not catalase, CuZnSOD, and glutathione peroxidase 1. The increased apoptosis by forced expression of BTG2/TIS21/PC3 could be inhibited by N-acetyl-l-cysteine and polyethylene glycol-catalase. These results therefore suggest that BTG2/TIS21/PC3 works as an enhancer of DOXO-induced cell death via accumulation of H2O2 by up-regulating manganese-superoxide dismutase without any other antioxidant enzymes. In summary, BTG2/TIS21/PC3 enhances cancer cell death by accumulating H2O2 via imbalance of the antioxidant enzymes in response to chemotherapy