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1.
Carcinogenesis ; 40(4): 569-579, 2019 06 10.
Article in English | MEDLINE | ID: mdl-30407516

ABSTRACT

The RNA-binding protein insulin-like growth factor 2 mRNA binding protein 1 (IMP1) is overexpressed in colorectal cancer (CRC); however, evidence for a direct role for IMP1 in CRC metastasis is lacking. IMP1 is regulated by let-7 microRNA, which binds in the 3' untranslated region (UTR) of the transcript. The availability of binding sites is in part controlled by alternative polyadenylation, which determines 3' UTR length. Expression of the short 3' UTR transcript (lacking all microRNA sites) results in higher protein levels and is correlated with increased proliferation. We used in vitro and in vivo model systems to test the hypothesis that the short 3' UTR isoform of IMP1 promotes CRC metastasis. Herein we demonstrate that 3' UTR shortening increases IMP1 protein expression and that this in turn enhances the metastatic burden to the liver, whereas expression of the long isoform (full length 3' UTR) does not. Increased tumor burden results from elevated tumor surface area driven by cell proliferation and cell survival mechanisms. These processes are independent of classical apoptosis pathways. Moreover, we demonstrate the shifts toward the short isoform are associated with metastasis in patient populations where IMP1-long expression predominates. Overall, our work demonstrates that different IMP1 expression levels result in different functional outcomes in CRC metastasis and that targeting IMP1 may reduce tumor progression in some patients.


Subject(s)
3' Untranslated Regions/genetics , Cell Proliferation , Colorectal Neoplasms/pathology , Liver Neoplasms/secondary , RNA-Binding Proteins/genetics , Animals , Apoptosis , Colorectal Neoplasms/genetics , Colorectal Neoplasms/metabolism , Gene Expression Regulation, Neoplastic , Humans , Liver Neoplasms/genetics , Liver Neoplasms/metabolism , Mice , Mice, Nude , RNA-Binding Proteins/metabolism , Tumor Cells, Cultured , Xenograft Model Antitumor Assays
2.
Bioconjug Chem ; 30(6): 1702-1710, 2019 06 19.
Article in English | MEDLINE | ID: mdl-31083974

ABSTRACT

Antibody-drug conjugates utilize the antigen specificity of antibodies and the potency of chemotherapeutic and antibiotic drugs for targeted therapy. However, as cancers and bacteria evolve to resist the action of drugs, innovative controlled release methods must be engineered to deliver multidrug cocktails. In this work, we engineer lipoate-acid ligase A (LplA) acceptor peptide (LAP) tags into the constant heavy and light chain of a humanized Her2 targeted antibody, trastuzumab. These engineered LAP tags, along with the glutamine 295 (Q295) residue in the heavy chain, were used to generate orthogonally cleavable site-specific antibody conjugates via a one-pot chemoenzymatic ligation with microbial transglutaminase (mTG) and LplA. We demonstrate orthogonal cargo release from these dual-labeled antibody bioconjugates via matrix metalloproteinase-2 and cathepsin-B-mediated bond cleavage. To the best of our knowledge, this is the first demonstration of temporal control on dual-labeled antibody conjugates, and we believe this platform will allow for sequential release and cooperative drug combinations on a single antibody bioconjugate.


Subject(s)
Antineoplastic Agents, Immunological/chemistry , Immunoconjugates/chemistry , Trastuzumab/chemistry , Antineoplastic Agents, Immunological/pharmacokinetics , Cell Line, Tumor , Drug Liberation , Humans , Immunoconjugates/pharmacokinetics , Models, Molecular , Peptide Synthases/chemistry , Peptides/chemistry , Trastuzumab/pharmacokinetics
3.
Cancer Discov ; 10(6): 854-871, 2020 06.
Article in English | MEDLINE | ID: mdl-32188706

ABSTRACT

Epithelial plasticity, reversible modulation of a cell's epithelial and mesenchymal features, is associated with tumor metastasis and chemoresistance, leading causes of cancer mortality. Although different master transcription factors and epigenetic modifiers have been implicated in this process in various contexts, the extent to which a unifying, generalized mechanism of transcriptional regulation underlies epithelial plasticity remains largely unknown. Here, through targeted CRISPR/Cas9 screening, we discovered two histone-modifying enzymes involved in the writing and erasing of H3K36me2 that act reciprocally to regulate epithelial-to-mesenchymal identity, tumor differentiation, and metastasis. Using a lysine-to-methionine histone mutant to directly inhibit H3K36me2, we found that global modulation of the mark is a conserved mechanism underlying the mesenchymal state in various contexts. Mechanistically, regulation of H3K36me2 reprograms enhancers associated with master regulators of epithelial-to-mesenchymal state. Our results thus outline a unifying epigenome-scale mechanism by which a specific histone modification regulates cellular plasticity and metastasis in cancer. SIGNIFICANCE: Although epithelial plasticity contributes to cancer metastasis and chemoresistance, no strategies exist for pharmacologically inhibiting the process. Here, we show that global regulation of a specific histone mark, H3K36me2, is a universal epigenome-wide mechanism that underlies epithelial-to-mesenchymal transition and mesenchymal-to-epithelial transition in carcinoma cells. These results offer a new strategy for targeting epithelial plasticity in cancer.This article is highlighted in the In This Issue feature, p. 747.


Subject(s)
Gene Expression Regulation, Neoplastic , Histone-Lysine N-Methyltransferase/genetics , Histones/genetics , Neoplasms/genetics , Epithelial-Mesenchymal Transition , Humans
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