Project description:The Ras-family small GTPase RAB25 is involved in numerous aspects of endosomal protein trafficking and cell polarity. Recent evidence has established a role for RAB25, as well as related RAB-family and effector proteins, in oncogenic signaling, highlighting the need for chemical probes targeting this class of proteins. Here we report the development of all-hydrocarbon stabilized peptides targeting RAB25 derived from the RAB-binding FIP-family of proteins. Relative to unmodified FIP peptides, optimized stapled peptides show markedly increased structural stability, binding affinity, cell permeability and inhibition of RAB25:FIP complex formation. RAB25 expression has been shown to promote both pro- and anti-oncogenic phenotypes in specific cellular contexts. Stapled peptide RFP14 treatment of breast and ovarian cancer cell lines, in which RAB25 is pro-oncogenic, inhibited migration and proliferation in a RAB25-dependent manner. In contrast, treatment of a triple-negative breast cancer cell line in which RAB25 is tumor suppressive augmented proliferation and migration. Gene expression (RNA Seq) profiling identified significantly altered transcripts in response to RAB25 expression in ovarian cancer cells, and treatment with the optimized stapled peptide RFP14 reversed this expression profile. These data validate first-in-class chemical probes targeting RAB-family proteins and support the role of RAB25 in regulating context-specific oncogenic phenotypes.
Project description:We and others have proposed that coactivator binding inhibitors, which block the interaction of estrogen receptor and steroid receptor coactivators, may represent a potential class of new breast cancer therapeutics. The development of coactivator binding inhibitors has been limited, however, because many of the current molecules which are active in in vitro and biochemical assays are not active in cell-based assays. Our goal in this work was to prepare a coactivator binding inhibitor active in cellular models of breast cancer. To accomplish this, we used molecular dynamics simulations to convert a high-affinity stapled peptide with poor cell permeability into R4K1, a cell-penetrating stapled peptide. R4K1 displays high binding affinity for estrogen receptor ɑ, inhibits the formation of estrogen receptor/coactivator complexes, and distributes throughout the cell with a high percentage of nuclear localization. R4K1 represses native gene transcription mediated by estrogen receptor ɑ and inhibits proliferation of estradiol-stimulated MCF-7 cells. Using RNA-Seq, we demonstrate that almost all of the effects of R4K1 on global gene transcription are estrogen receptor-associated. This chemical probe provides a significant proof-of-concept for preparing cell-permeable stapled peptide inhibitors of the estrogen receptor/coactivator interaction.
Project description:Excessive Toll-like receptor (TLR) and NF-kB activation during infection causes the overactivation of inflammatory pathways seen in sepsis. Thrombin-derived C-terminal peptides (TCPs) target both bacteria and the resulting TLR-mediated inflammatory response during infection. The present study describes the design and development of a novel multifunctional stapled peptide mimicking the actions of such immunomodulatory TCPs, providing a new drug class based on nature’s own anti-infective strategies. Using a combination of structure-based design, nuclear magnetic resonance spectroscopy (NMR), biophysics, mass spectrometry, microbiology, cellular, and in vivo studies, we describe the development of a structurally locked active stapled form of the endogenous peptide HVFRLKKWIQKVIDQFGE, denoted sHVF18. The stapled peptide shows a higher affinity to CD14 than the linear peptide, retains a partly helical and stabilized structure, and is protease resistant. In vivo, it shows efficacy in experimental models of endotoxin shock in mice and pigs and increases survival in mouse models of polymicrobial sepsis.
Project description:DNA-binding transcription factors (TFs) have been challenging to target with molecular probes. Many TFs function in part through interaction with Mediator; we sought to block p53 function by disrupting the p53-Mediator interaction. Through rational design and activity-based screening, we characterized a stapled peptide, with functional mimics of both p53 activation domains, that selectively disrupted p53- and Mediator-dependent transcription in vitro. This “bivalent peptide” also suppressed p53 transcriptional response in human cancer cells. Our strategy circumvents the TF and instead targets the TF-Mediator interface, with desired transcriptional outcomes. Different TFs target Mediator through different subunits, suggesting this strategy could be generalizable.
Project description:DNA-binding transcription factors (TFs) have been challenging to target with molecular probes. Many TFs function in part through interaction with Mediator; we sought to block p53 function by disrupting the p53-Mediator interaction. Through rational design and activity-based screening, we characterized a stapled peptide, with functional mimics of both p53 activation domains, that selectively disrupted p53- and Mediator-dependent transcription in vitro. This “bivalent peptide” also suppressed p53 transcriptional response in human cancer cells. Our strategy circumvents the TF and instead targets the TF-Mediator interface, with desired transcriptional outcomes. Different TFs target Mediator through different subunits, suggesting this strategy could be generalizable.
Project description:Transcriptional profiling of Homo sapiens inflammatory skin diseases (whole skin biospies): Psoriasis (Pso), vs Atopic Dermatitis (AD) vs Lichen planus (Li), vs Contact Eczema (KE), vs Healthy control (KO) In recent years, different genes and proteins have been highlighted as potential biomarkers for psoriasis, one of the most common inflammatory skin diseases worldwide. However, most of these markers are not psoriasis-specific but also found in other inflammatory disorders. We performed an unsupervised cluster analysis of gene expression profiles in 150 psoriasis patients and other inflammatory skin diseases (atopic dermatitis, lichen planus, contact eczema, and healthy controls). We identified a cluster of IL-17/TNFα-associated genes specifically expressed in psoriasis, among which IL-36γ was the most outstanding marker. In subsequent immunohistological analyses IL-36γ was confirmed to be expressed in psoriasis lesions only. IL-36γ peripheral blood serum levels were found to be closely associated with disease activity, and they decreased after anti-TNFα-treatment. Furthermore, IL-36γ immunohistochemistry was found to be a helpful marker in the histological differential diagnosis between psoriasis and eczema in diagnostically challenging cases. These features highlight IL-36γ as a valuable biomarker in psoriasis patients, both for diagnostic purposes and measurement of disease activity during the clinical course. Furthermore, IL-36γ might also provide a future drug target, due to its potential amplifier role in TNFα- and IL-17 pathways in psoriatic skin inflammation. In recent years, different genes and proteins have been highlighted as potential biomarkers for psoriasis, one of the most common inflammatory skin diseases worldwide. However, most of these markers are not psoriasis-specific but also found in other inflammatory disorders. We performed an unsupervised cluster analysis of gene expression profiles in 150 psoriasis patients and other inflammatory skin diseases (atopic dermatitis, lichen planus, contact eczema, and healthy controls). We identified a cluster of IL-17/TNFα-associated genes specifically expressed in psoriasis, among which IL-36γ was the most outstanding marker. In subsequent immunohistological analyses IL-36γ was confirmed to be expressed in psoriasis lesions only. IL-36γ peripheral blood serum levels were found to be closely associated with disease activity, and they decreased after anti-TNFα-treatment. Furthermore, IL-36γ immunohistochemistry was found to be a helpful marker in the histological differential diagnosis between psoriasis and eczema in diagnostically challenging cases. These features highlight IL-36γ as a valuable biomarker in psoriasis patients, both for diagnostic purposes and measurement of disease activity during the clinical course. Furthermore, IL-36γ might also provide a future drug target, due to its potential amplifier role in TNFα- and IL-17 pathways in psoriatic skin inflammation.