Saturday, April 19, 2014

Extracellular Matrix Environment and Chemotherapeutics

Substrate Matters!

Neuromics' has been promoting a variety of 3-D Cell Based Assay Solutions for the past several years. These include: Nanofibers, Hydrogels and Extracellular Matrix (ECM) Proteins. We have found that the adoption rate for these as standard tools for drug discovery is slower that we anticipated.

We believe substrate matters so I am pleased to share a recent publication that references use of our Collagen IV and other ECM proteins. This confirms the importance of using a more in vivo like environment in testing chemotherapeutics: Thuy V. Nguyen,Marianne Sleiman,Timothy Moriarty,William G. Herrick,Shelly R. Peyton. Sorafenib resistance and JNK signaling in carcinoma during extracellular matrix stiffening. Publication: Biomaterials. Elsevier. 13 April 2014.

Abstract: Tumor progression is coincident with mechanochemical changes in the extracellular matrix (ECM). We hypothesized that tumor stroma stiffening, alongside a shift in the ECM composition from a basement membrane-like microenvironment toward a dense network of collagen-rich fibers during tumorigenesis, confers resistance to otherwise powerful chemotherapeutics. To test this hypothesis, we created a high-throughput drug screening platform based on our poly(ethylene glycol)-phosphorylcholine (PEG-PC) hydrogel system, and customized it to capture the stiffness and integrin-binding profile of in vivo tumors. We report that the efficacy of a Raf kinase inhibitor, sorafenib, is reduced on stiff, collagen-rich microenvironments, independent of ROCK activity. Instead, sustained activation of JNK mediated this resistance, and combining a JNK inhibitor with sorafenib eliminated stiffness-mediated resistance in triple negative breast cancer cells. Surprisingly, neither ERK nor p38 appears to mediate sorafenib resistance, and instead, either ERK or p38 inhibition rescued sorafenib resistance during JNK inhibition, suggesting negative crosstalk between these signaling pathways on stiff, collagen-rich environments. Overall, we discovered that β1 integrin and its downstream effector JNK mediate sorafenib resistance during tumor stiffening. These results also highlight the need for more advanced cell culture platforms, such as our high-throughput PEG-PC system, with which to screen chemotherapeutics.

Figure: High-throughput biomaterial platform for drug screening. (A) The high-throughput platform consists of a black-walled, glass bottom plate, with PEG-PC gels cast in each of the inner 6x10 wells. (B) Gels can be functionalized with any protein or peptide of interest, and they support the adhesion and growth of carcinoma cells. We used this platform to test carcinoma cell response to a kinase inhibitor (sorafenib) as a function of underlying gel stiffness and ECM adhesive protein cocktail. (C) A representative graph of SkBr3 proliferation (y-axis) in response to sorafenib (x-axis) across a range of gel stiffness (colors) demonstrates the IC-50 calculation.

This confirms the importance of considering your substrate environment when developing your in vitro assays for High Content and High Throughput Drug Discovery. We will continue to provide updates.

Thursday, April 17, 2014

HIV-1R Viral Protein R and Memory Impairment

Using Synpatophysin as Marker for Synaptic Loss

Our Neuron-Glial Markers continue to shine in challenging applications. Here researchers examined whether infusion of the Vpr-expressing astrocytes affected synaptophysin expression in the hippocampus. The authors of the study, using Neuromics' Mouse Monoclonal Synaptophysin Antibody,  found a significant reduction in synaptophysin staining in CA3: Lilith Torres and Richard J Noel. Astrocytic expression of HIV-1 viral protein R in the hippocampus causes chromatolysis, synaptic loss and memory impairment. Journal of Neuroinflammation 2014, 11:53 doi:10.1186/1742-2094-11-53.

Images: Astrocytic HIV-1 viral protein R (Vpr) expression decreased synaptophysin immunoreactivity (A) Representative light photomicrograph showing the distribution of synaptophysin immunoreactivity in the rat hippocampal CA3 formation. Green fluorescent protein (GFP) right side. Vpr shows both left and right. Magnification 100×. (B) Densitometric analysis revealed significantly decreased mean value for the Vpr group compare to control.

Protocol: To examine changes in synaptophysin between control and HIV-1 Vpr exposed rats, tissue sections from each group were processed for immunocytochemistry. The samples were cut at 4 μm thickness with a microtome (Microm HM340, Microm International) and fixed to positively charged microscope slides. Fixed tissues were deparaffinized in xylene substitute for 30 minutes, rehydrated through graded alcohols and neutralized with 3% hydrogen peroxide (Sigma-Aldrich), followed by a rinse under running tap water and immersion in antigenretrieval solution (0.01 M citrate, pH 6.0) for 1 minute at 98°C. Then sections were washed in TBS for 5 minutes and treated with blocking solution containing normal goat serum (BioGenex, cat# HK112-9KE). Sections were incubated for 24 hrs at 4°C in mouse monoclonal antisynaptophysin antibody (Neuromics, cat # MO20000, 1:500 dilutions). Negative controls with TBS instead of primary antibody were run in each slide. Primary antibody was washed in TBS buffer for 2 × 5 minutes and incubated with Multi Link secondary antibody (Super Sensitive Link-Label IHC Detection System, cat# LP000- ULE, BioGenex, San Ramon, CA, USA). Secondary antibody was washed in TBS and incubated in ABC-HRP, washed in TBS buffer and incubated in 3,3′-diaminobenzidine (cat# HK153-5KE, Biogenex, San Ramon, CA, USA). Slides were rinsed in water and counterstained with hematoxylin for 30 sec. The sections were rinsed, dehydrated and and mounted with Cytoseal XYL (cat# 8312-4, Richard Allan Scientific, Kalamazoo, MI, USA). For quantitative densitometry, images of regions of interest (ROI) in the CA3 were captured from 5 rats in each group using NIH Image J 1.50 software.

We will continue to work hard to fill all your Neuroscience Research Needs.

Friday, April 04, 2014

Osteoblast Activators and Musculoskeletal Disease Assays

We now have the ability to precisely test human Osteoblast activating agents. Tools available include:

  1.  Live cell screening
  2. Quantibody Bone Metabolism Arrays
  3. PCR
  4. Flow Cytometry
  5. Immunostaining
  6. Western Blotting
This means we can generate data that provides you a clear picture of the effects of small molecules/compounds on the activation, expansion and migration of Osteoblasts. Here's an example.

Image: Activin A expression from Osteoblasts treated with Activators vs Controls

We will soon be releasing a turn-key assay for Osteoporosis Drug Discovery. We can also run custom assays that fit your specific requirements. To learn more, you can call (612-801-1007) or e-mail: Thank you. Pete Shuster, CEO and Owner, Neuromics.