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In JoVE (1)
Other Publications (2)
Articles by Stephen P. Winter in JoVE
JoVE Bioengineering
Preparation of Complaint Matrices for Quantifying Cellular Contraction
1Institute for Biophysical Dynamics, University of Chicago, 2Physics Department - James Franck Institute, University of Chicago, 3Interdisciplinary Scientist Training Program, University of Chicago
In this video, we demonstrate the experimental techniques used to fabricate compliant, extracellular matrix (ECM) coated substrates suitable for cell culture, and which are amenable to traction force microscopy and observing effects of ECM stiffness on cell behavior.
Other articles by Stephen P. Winter on PubMed
Inhibition of Hedgehog Signaling Enhances Delivery of Chemotherapy in a Mouse Model of Pancreatic Cancer
Pancreatic ductal adenocarcinoma (PDA) is among the most lethal human cancers in part because it is insensitive to many chemotherapeutic drugs. Studying a mouse model of PDA that is refractory to the clinically used drug gemcitabine, we found that the tumors in this model were poorly perfused and poorly vascularized, properties that are shared with human PDA. We tested whether the delivery and efficacy of gemcitabine in the mice could be improved by coadministration of IPI-926, a drug that depletes tumor-associated stromal tissue by inhibition of the Hedgehog cellular signaling pathway. The combination therapy produced a transient increase in intratumoral vascular density and intratumoral concentration of gemcitabine, leading to transient stabilization of disease. Thus, inefficient drug delivery may be an important contributor to chemoresistance in pancreatic cancer.
C-Raf Inhibits MAPK Activation and Transformation by B-Raf(V600E)
Activating B-Raf mutations that deregulate the MAPK pathway commonly occur in cancer. Whether additional proteins modulate the enzymatic activity of oncogenic B-Raf is unknown. Here we show that the proto-oncogene C-Raf paradoxically inhibits B-Raf(V600E) kinase activity through the formation of B-Raf(V600E)-C-Raf complexes. Although all Raf family members associate with oncogenic B-Raf, this inhibitory effect is specific to C-Raf. Indeed, a B-Raf(V600E) isoform with impaired ability to interact with C-Raf exhibits elevated oncogenic potential. Human melanoma cells expressing B-Raf(V600E) display a reduced C-Raf:B-Raf ratio, and further suppression of C-Raf increases MAPK activation and proliferation. Conversely, ectopic C-Raf expression lowers ERK phosphorylation and proliferation. Moreover, both oncogenic Ras and Sorafenib stabilize B-Raf(V600E)-C-Raf complexes, thereby impairing MAPK activation. This inhibitory function of C-Raf on B-Raf(V600E)-mediated MAPK activation may explain the lack of co-occurrence of B-Raf(V600E) and oncogenic Ras mutations, and influence the successful clinical development of small molecule inhibitors for B-Raf(V600E)-driven cancers.
