Project description:Our previous studies demonstrated that specific inhibition of the BIG3-PHB2 complex, which is indispensable for estrogen (E2)-signaling activation, using ERAP, a dominant-negative peptide inhibitor, leads to the suppression of E2-dependent breast cancer cell growth in vitro and in vivo. However, duration of its effect is very short for clinical use. Here, we developed the chemically modified ERAP using stapling methods (stERAP; stapled ERAP) to improve duration of their antitumor effects. Tumor bearing mice treated with every 4 and 7 days with stERAP (1 mg/kg body weight) treatment effectively prevented the BIG3-PHB2 interaction, thereby releasing PHB2 to directly bind to both nuclear- and cytoplasmic ERalpha. This event led to the complete suppression of the E2-signalling pathways and ERalpha-positive breast cancer cell growth both in vitro and in vivo, but did not suppress the growth of normal mammary epithelial cells. Our findings suggest that the chemically modified stERAP may be a promising anti-tumor drug to suppress the growth of luminal-type breast cancer in clinical use.
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:ERα17p is a synthetic peptide corresponding to the sequence P295LMIKRSKKNSLALSLT311 of the estrogen receptor alpha (ERα) and initially synthesized to mimic its calmodulin binding site. ERα17p was subsequently found to elicit estrogenic responses in E2-deprived ERα-positive breast cancer cells, increasing proliferation and E2-dependent gene transcription. Surprisingly, in E2-supplemented media, ERα17p induced apoptosis and modified the actin network, influencing thereby cell motility. Here, we report that ERα17p induces a massive early (3h) transcriptional activity in breast cancer cell line T47D.
Project description:ERα17p is a synthetic peptide corresponding to the sequence P295LMIKRSKKNSLALSLT311 of the estrogen receptor alpha (ERα) and initially synthesized to mimic its calmodulin binding site. ERα17p was subsequently found to elicit estrogenic responses in E2-deprived ERα-positive breast cancer cells, increasing proliferation and E2-dependent gene transcription. Surprisingly, in E2-supplemented media, ERα17p induced apoptosis and modified the actin network, influencing thereby cell motility. Here, we report that ERα17p induces a massive early (3h) transcriptional activity in breast cancer cell line MDA-MB-231.
Project description:Estrogen receptor alpha (ERalpha) is a ligand-dependent transcription factor that plays an important role in breast cancer. Estrogen-dependent gene regulation by ERalpha can be mediated by interaction with other DNA-binding proteins, such as activator protein-1 (AP-1). The nature of such interactions in mediating the estrogen response in breast cancer cells remains unclear. Here we show that knockdown of c-Fos, a component of the transcription factor AP-1, attenuates the expression of 37% of all estrogen-regulated genes, suggesting that AP-1 is a fundamental factor for ERalpha-mediated transcription. Additionally, knockdown of c-Fos affected the expression of a number of genes that were not regulated by estrogen. Pathway analysis reveals that silencing of c-Fos downregulates an E2F1-dependent pro-proliferative gene network. Thus, modulation of the E2F1 pathway by c-Fos represents a novel mechanism by which c-Fos enhances breast cancer cell proliferation. Furthermore, we show that c-Fos and ERalpha can cooperate in regulating E2F1 gene expression by binding to regulatory elements in the E2F1 promoter. To start to dissect the molecular details of the cross-talk between AP-1 and estrogen signaling, we identify a novel ERalpha/AP-1 target, PKIB (cAMP-dependent protein kinase inhibitor-beta), which is overexpressed in ERalpha-positive breast cancer tissues. Knockdown of PKIB by siRNA results in drastic growth suppression of breast cancer cells. Collectively, our findings support AP-1 as a critical factor that governs estrogen-dependent gene expression and breast cancer proliferation programs. MCF-7 cells were transfected with a control siRNA or with the pool of siRNAs targeting c-Fos for 72 h and were then treated with vehicle or E2 for 24 h, and global gene expression profiles were assessed. Three or four biological replicates were used for each group.
Project description:In the rapidly advancing field of synthetic biology, there exists a critical need for technology to discover targeting moieties for therapeutic biologics. We are developing developed INSPIRE-seq, an approach that utilizes a nanobody library and next-generation sequencing to identify nanobodies selected for complex environments. INSPIRE-seq enables the parallel enrichment of immune cell-binding nanobodies that penetrate the tumor microenvironment. Clone enrichment and specificity vary varies across immune cell subtypes in the tumor, lymph node, and spleen. INSPIRE-seq identified a dendritic cell binding clone that binds PHB2. Single-cell RNA sequencing revealed a connection with cDC1s, and immunofluorescence confirmed nanobody-PHB2 colocalization along cell membranes. Structural modeling and docking studies assisted binding predictions and will guide nanobody selection. In this work, we demonstrate that INSPIRE-seq offers an unbiased approach to examine complex microenvironments and assist in the development of nanobodies, which could serve as active drugs, modified to become drugs, or used as targeting moieties. microenvironment, which can be distinct from draining lymph nodes. To identify targets, we selected a clone enriched for dendritic cells that binds to PHB2. Using single cell RNA sequencing, we observe PHB2 signaling is associated with activation in cDC1’s. Immunofluorescence confirmed that the nanobody colocalizes with PHB2 in regions along the cell membrane. Structural modeling with AlphaFold2 and antibody docking using Rosetta assist binding site predictions, thus could be used to guide nanobody selection for future aims. This work shows that INSPIRE-seq can interrogate complex microenvironments and may assist in developing therapeutics.
Project description:The spatial co-presence of aberrant long non-coding RNAs (lncRNAs) and abnormal coding genes contribute to the development of the malignancy in various tumors. However, precise coordinated mechanisms underlying this co-presence phenomenon in tumorigenesis remains incompletely understood. Here, we for the first time showed that PHB2 coordinately crosslinked transcription of a novel oncogenic CANT1-New-Isoform 2 (CANT2) lncRNA and coding tumor-suppressor gene CCBE1 for accelerating tumorigenesis of melanoma. In melanoma cells, PHB2 initially accessed open chromatin sites of the promoter of CANT2 lncRNA and recruited MLL2, resulting in an augmented H3K4 trimethylation and activating the transcription of CANT2. Intriguingly, PHB2 further bound with activated CANT2 transcript for targeting interaction with the promoter of tumor-suppressor CCBE1, recruiting histone deacetylase HDAC1 to decrease H3K27 acetylation of CCBE1 promoter and inhibiting CCBE1 transcription for significantly promoting cell growth and metastasis in vitro and in vivo. Our study elucidated a novel PHB2-mediating mechanism that crosslinked aberrant transcription of lncRNA and coding gene, thereby providing an interesting “one stone two birds” model in tumorigenesis.
Project description:ERα17p is a synthetic peptide corresponding to the sequence P295LMIKRSKKNSLALSLT311 of the estrogen receptor alpha (ERα) and initially synthesized to mimic its calmodulin binding site. ERα17p was subsequently found to elicit estrogenic responses in E2-deprived ERα-positive breast cancer cells, increasing proliferation and E2-dependent gene transcription. Surprisingly, in E2-supplemented media, ERα17p induced apoptosis and modified the actin network, influencing thereby cell motility. Here, we report that ERα17p induces a massive early (3h) transcriptional activity in breast cancer cell lines SKBR3). Remarkably, about 75% of the significantly modified transcripts were also modified by E2, confirming the pro-estrogenic profile of ERα17p. The different ER spectra of the used cell lines allowed us to extract a specific ERα17p signature related to ERα and its variant ERα36. With respect to ERα, the peptide activates nuclear (cell cycle, cell proliferation, nucleic acid and protein synthesis) and extranuclear signaling pathways. In contrast, through ERα36 it exerts inhibitory events on inflammation and cell cycle and inhibition of EGFR signaling. This is the first work reporting ERα36 specific transcriptional effects. The fact that a number ERα17p-induced transcripts is different from those activated by E2 revealed that the apoptosis and actin modifying effects of ERα17p are independent from the ER-related actions of the peptide.
Project description:Citrullinated and unmodified peptides (>95% purity, ProImmune AB) were immobilized onto a chemically modified glass slide, sera from RA patients and healthy controls were applied into the reactions sites and fluorescence intensity after incubation with anti-human IgG antibody was acquired in a laser scanner. Final results for each citrullinated peptide were calculated by subtracting the intensity values of corresponding arginine containing control peptide from citrullinated peptide for all RA patients and controls.
Project description:Estrogen receptor (ER)-positive MCF7 breast cancer cells were treated with siRNAs targeting CHRNA5, TP53, or both in combination to investigate TP53-dependent and independent transcriptional responses to CHRNA5 knockdown. Previous studies have shown that CHRNA5 silencing induces cell death via TP53 pathway activation. To further elucidate the molecular mechanisms underlying this effect, we performed RNA sequencing following 72-hour treatments with siCHRNA5, siTP53, and their combination, alongside appropriate siRNA controls. This dataset provides a valuable resource for understanding the role of CHRNA5 in ER-positive breast cancer and its interaction with TP53 signaling, with implications for therapeutic targeting strategies.