Abstract 429: Androgen receptor (AR) N-terminal domain degraders can degrade AR full length and AR splice variants in CRPC preclinical models

Introduction: Androgen receptor (AR) signaling is a main driver of prostate cancer progression and remains a crucial target for therapeutic intervention even in late stages of the disease. Current antiandrogen therapies directly or indirectly target the AR ligand binding domain (LBD) and are initially effective in prostate cancer patients. However, resistance ultimately develops, and new methods of inhibiting the AR pathway are needed. The selective targeting of the N-terminal domain (NTD) of the AR by small molecule anitens represents a novel method of blocking AR signaling that can bypass LBD-related resistance mechanisms. AR NTD is an intrinsically disordered region (IDR) which has no stable ordered structure and is generally regarded as an undruggable target due to the lack of a well-defined small-molecule binding pocket. However, we recently demonstrated that EPI-7386, an AR NTD small molecule inhibitor, inhibits AR activity by binding to Tau5 region of the NTD. By developing an aniten based bifunctional degrader (ANITAC for ANITen bAsed Chimera), our goal is to eliminate any forms of AR protein found in castration-resistant prostate cancer (CRPC), that can potentially drive disease progression, including LBD mutants and AR truncated variants.

Methods: AR degradation was monitored by Western Blot or by using the HiBit assay. AR transcriptional activity was measured using different reporter assays following AR full length (FL) or truncated AR activity in in vitro models.

Results: Here we report the first series of AR degraders targeting the NTD of AR, which lead to degradation of all forms of AR, including AR-V7 and AR-v567es. ANITACs eliminate AR in all cell lines tested through an E3 ligase dependent mechanism, with an observed 50% degradation concentration (DC50) < 20 nM in 22Rv1 cells for the most potent compounds. AR degradation mediated by ANITACs suppresses the expression of AR target genes and decreases the viability of prostate cancer cells. ANITACs also degrade clinically relevant AR mutants and AR splice variants and show inhibition of AR transcriptional activity in multiple cell lines expressing different forms of AR including AR FL (LNCaP, CWR-AD1), AR-V7 (22Rv1), AR-V567es (CWR-D567). In vitro and in vivo PK studies show the compounds are metabolically stable and exhibit excellent oral bioavailability in mice.

Conclusion: In summary, we report preclinical data on the first generation of ANITAC molecules, that can be orally bioavailable and show activity against forms of AR expressed in late stage CRPC patients.

Citation Format: Nan Hyung Hong, Berenger Biannic, Peter Virsik, Han-Jie Zhou, Ronan Le Moigne. Androgen receptor (AR) N-terminal domain degraders can degrade AR full length and AR splice variants in CRPC preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 429.

Abstract P192: Comprehensive preclinical characterization of the mechanism of action of EPI-7386, an androgen receptor N-terminal domain inhibitor

Background: Androgen receptor (AR) signaling is a main driver of prostate cancer progression and remains a crucial target for therapeutic intervention even in late stages of the disease. While current anti-androgen therapies targeting directly or indirectly the AR ligand binding domain (LBD) are initially effective, resistance ultimately develops, and new methods of inhibiting the AR pathway are needed. The selective targeting of the N-terminal domain (NTD) of the AR represents a novel method of blocking AR signaling to by-pass LBD-related resistance. EPI-7386 is a potent and metabolically stable NTD inhibitor (aniten) currently in a phase 1 dose-escalation study in mCRPC patients (NCT04421222). Here we further characterized the binding to AR NTD and the mechanism of action of EPI-7386. Methods: Target engagement was measured by Cellular Thermal Shift Assay (CETSA) and two-dimensional Nuclear Magnetic Resonance (2D NMR) spectroscopy. The potency and selectivity of EPI-7386 was determined in cellular models expressing different forms of AR using reporter and cell viability assays. qPCR, NanoString, and RNA sequencing were used to explore the activity of EPI-7386 on the AR transcriptome. To determine the effect of EPI-7386 on AR genomic occupancy, Chromatin immunoprecipitation sequencing (ChIP-seq) was performed. Results: We confirmed target engagement of EPI-7386 with an LBD truncated AR variant by CETSA using a cell line which expresses only AR-V567es, suggesting the interaction of EPI-7386 with AR NTD. In the same cell line, AR antagonist enzalutamide that binds to AR LBD showed no target engagement with AR-V567es. Furthermore, 2D NMR study results demonstrate an interaction of EPI-7386 with amino acid residues located in the transcription activation unit 5 (Tau-5) region of the AR NTD, a region which has been described to be involved in interactions with transcriptional cofactors such as CBP/p300. EPI-7386 strongly impaired the transcriptional activity and gene expression driven exclusively by LBD truncated AR variants including AR-V567es and AR-V7 and decreased cell viability. EPI-7386 has been shown to suppress the AR regulated transcriptome and the combination of EPI-7386 with lutamides resulted in broader and deeper inhibition of AR-regulated gene expression. The analysis of the AR cistrome by ChIP-seq showed that EPI-7386 displaces genome-wide androgen induced AR binding and the combination with enzalutamide completely abrogated AR binding. Conclusion: EPI-7386 is a potent AR NTD inhibitor that has the capacity to by-pass AR LBD resistance mechanisms to current anti-androgen therapies by uniquely inhibiting AR-mediated signaling. The agent has the potential for providing clinical benefit as a single agent in patients whose tumors are progressing on anti-androgens or in combination with current anti-androgens in earlier line patients.

Citation Format: Nan Hyung Hong, Shihua Sun, Peter Virsik, Alessandra Cesano, Elahe A. Mostaghel, Stephen R. Plymate, Berenger Biannic, Han-Jie Zhou, Ronan Le Moigne. Comprehensive preclinical characterization of the mechanism of action of EPI-7386, an androgen receptor N-terminal domain inhibitor [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P192.

Abstract 1209: Comprehensive in vitro characterization of the mechanism of action of EPI-7386, an androgen receptor N-terminal domain inhibitor

The androgen receptor (AR) is a key driver in the growth of prostate cancer and remains a crucial target for therapeutic intervention even in late stages of the disease. While current anti-androgen therapies targeting directly or indirectly the AR ligand binding domain (LBD) are initially effective, resistance ultimately develops. The selective targeting of the N-terminal domain (NTD) of the AR represents a novel method of blocking AR signaling to by-pass LBD-related resistance. EPI-7386 is a potent and metabolically stable NTD inhibitor (aniten) currently in a phase 1 dose-escalation study in mCRPC patients. Here we report the results of a comprehensive in vitro characterization of its mechanism of action. The potency and selectivity of EPI-7386 was determined in cellular models expressing different forms of AR using reporter and cell viability assays. Target engagement was measured by a Cellular Thermal Shift Assay (CETSA). Both Nanostring and RNAseq were used to explore the activity of EPI-7386 on the AR transcriptome. Chromatin immunoprecipitation (ChIP)-seq and ChIP-qPCR were carried out to determine the effect of EPI-7386 on AR genomic occupancy. EPI-7386 exhibited potent activity in inhibiting full-length AR (AR-FL) driven transcriptional activity and also strongly impaired the transcriptional activity and the viability of cellular models driven exclusively by truncated AR protein. Using CETSA, we confirmed that EPI-7386 induced a thermal shift of both AR-FL and AR-V7 (lacking the AR LBD) in LNCaP and LNCaP95, respectively, which is an indication of AR target engagement by EPI-7386. ChIP analyses allowed a deeper understanding of epigenetic and transcriptional regulation driven by EPI-7386. It showed EPI-7386 inhibits androgen-activated AR binding to target gene loci such as KLK3. Additionally, EPI-7386 suppresses AR-regulated target gene expression in a comparable manner as lutamides in three human prostate cancer cell lines, LNCaP, 22Rv1, and VCaP, with a few notable exceptions. As a consequence, the combination of EPI-7386 with lutamides resulted in broader and deeper inhibition of AR-associated transcriptional activity in both LNCaP and VCaP cells. In AR-V7 driven cell lines, LNCaP95 and 22Rv1, EPI-7386 showed superior activity to enzalutamide in inhibiting AR-regulated genes expression. In conclusion, EPI-7386 is a potent AR NTD inhibitor that has the capacity to by-pass AR LBD resistance mechanisms to current anti-androgen therapies by uniquely inhibiting AR-mediated signaling. The agent has the potential for providing clinical benefit as a single agent in patients whose tumors are progressing on anti-androgens or in combination with current anti-androgens in earlier line patients. The Phase I dose escalation first in human clinical trial of EPI-7386 single agent (NCT04421222) is currently enrolling.

Citation Format: Nan Hyung Hong, Shihua Sun, Peter Virsik, Alessandra Cesano, Elahe A. Mostaghel, Stephen R. Plymate, Han-Jie Zhou, Ronan Le Moigne. Comprehensive in vitro characterization of the mechanism of action of EPI-7386, an androgen receptor N-terminal domain inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1209.

Preclinical and clinical pharmacology of EPI-7386, an androgen receptor N-terminal domain inhibitor for castration-resistant prostate cancer

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Background: EPI-7386 is the newest of the “anitens”, a new class of compounds designed to inhibit androgen receptor activity by binding to the N-terminal domain (NTD) of the AR. Through this novel method of AR inhibition, anitens can block AR transcription even in the presence of AR ligand-binding domain (LBD) resistance mechanisms including point mutations and splice variants. Compared to the first generation aniten, EPI-506, which showed poor pharmacokinetic properties in patients, EPI-7386 is metabolically stable in vitro and in vivo. A Phase 1 clinical trial of EPI-7386 in metastatic castration-resistant prostate cancer patients failing standard of care therapies is ongoing and the pharmacokinetic properties of the drug in preclinical models as well as in the initial cohort of patients are presented. Methods: The metabolic stability of EPI-7386 was evaluated in vitro in mouse, rat, dog, monkey, and human hepatocytes. Projected PK parameters in humans were estimated from in vitro and in vivo clearance correlation (IVIVC). Induction of CYP isoforms was evaluated in human hepatocyte cultures. In patients, plasma concentrations of EPI-7386 were determined by LC-MS-MS, and 4-beta-hydroxycholesterol levels in plasma were followed over time as an indirect indicator of CYP3A induction. Results: In vitro hepatocyte studies demonstrated good metabolic stability for EPI-7386 with an in vitro half-life > 360 min. In animal PK studies, the terminal half-life of EPI-7386 was approximately 5.8 hours in mouse, 4.9 hours in rat, 13.4 hours in dog and the plasma clearance was low across species. The oral bioavailability of EPI-7386 ranged from 33–112% in mouse to > 100% in rat and dog. Using IVIVC, a predicted human clearance of 0.16–0.39 mL/min/kg was calculated for EPI-7386, which was in line with allometric scaling from animal PK parameters. Human PK profiles of different doses of EPI-7386 were simulated using predicted oral bioavailability, clearance, and volume of distribution. Cmax and AUC0–24h for the Phase 1 first-in-human study (NCT04421222) starting dose of 200 mg dose were predicted to be 6,915 ng/mL and 137,278 ng•h/mL respectively. A comparison between estimated PK parameters and actual values observed in the first patient cohort will be presented. Human hepatocyte CYP induction studies showed that EPI-7386 is not an inducer of CYP1A2 but may have the potential to induce CYP2B6 and CYP3A4. A comparison of 4-beta-hydroxy cholesterol levels measured during the phase 1 will be presented along with a comparison drawn from in vitro models. Conclusions: Pre-clinical characterization predicts that EPI-7386 has the appropriate PK and metabolic properties to afford exposure in patients at potentially efficacious levels following once-daily oral administration. PK measurements in the initial cohort of patients treated in the Phase 1 study will be presented. Clinical trial information: NCT04421222.

Abstract 1953: Pre-clinical development of the second-generation N-terminal domain androgen receptor inhibitor, EPI-7386, for the treatment of prostate cancer

Background: The vast majority of metastatic castration-resistant prostate cancers (mCRPC) progress with rising prostate-specific antigen, underlying a persistent dependence on the androgen receptor (AR) pathway. Despite standard of care treatment targeting the AR axis, anti-androgen resistance inevitably arise and involve mechanisms including AR gene amplification, ligand-binding domain (LBD) mutations and expression of constitutively active AR splice variants lacking the LBD (e.g. AR-V7). Selective inhibition of the N-terminal domain (NTD) of the AR can inhibit its transcriptional activity even in the presence of LBD-driven resistance. EPI-7386 is a potent and stable second generation NTD inhibitor (Aniten) currently in preclinical development. The efficacy, safety profile and distinct mechanism of action of this molecule in LBD inhibitor resistant CRPC models will be presented.

Methods: EPI-7386 potency was assessed using reporter cellular models, or viability assays in a variety of cell lines, expressing or not the AR. Pharmacodynamic markers of activity in AR full length or AR-V7 driven models was determined by qPCR or RNAseq. The stability and selectivity of the molecule were characterized with screening and functional assays, while safety was assessed in specific IND enabling studies.

Results: EPI-7386 has an IC50 of 421 nM in LNCaP reporter assays, a similar range to the most active LBD inhibitors, but contrary to these drugs, antitumor activity was maintained in models of CRPC expressing AR-V7. As expected, no activity was observed in non-AR driven models. EPI-7386 can inhibit effectively the expression of AR full length driven genes (PSA, FKBP5 or STEAP4), but can also modulate the expression of genes driven by AR V7, including UBE2C or B4GALT1. Additionally, EPI-7386 also demonstrated remarkable activity in several models in vivo, including a CRPC patient derived xenograft (PDX) resistant to enzalutamide (ENZ). Interestingly, RNAseq analysis showed on target activity, but with a different transcriptomic profile than ENZ, which suggests that the combination of both LBD and NTD AR inhibition could provide more robust and thorough inhibition of the AR-pathway. The enhanced activity of such combination was confirmed in vivo in the CRPC model VCaP. IND-enabling studies demonstrated on target activity, and well-tolerated profile for EPI-7386, supporting an IND filing in 1Q 2020. Early clinical development plans including efficacy endpoints will be presented.

Conclusions: The second generation aniten compound EPI-7386 is more active and metabolically stable than EPI-506. It has a favorable safety and ADME profile, with predicted long half-life in human, supporting once daily dose. In vivo, EPI-7386 demonstrated potential as a single agent in overcoming anti-androgen clinical resistance as well as in combination therapy. The clinical strategy supporting the development of this new generation of aniten will be discussed.

Citation Format: Nan Hyung Hong, Ronan Le Moigne, C. Adriana Banuelos, Nasrin R. Mawji, Teresa Tam, Jun Wang, Raymond J. Andersen, Alessandra Cesano, Marianne D. Sadar, Han-Jie Zhou, Peter Virsik. Pre-clinical development of the second-generation N-terminal domain androgen receptor inhibitor, EPI-7386, for the treatment of prostate cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1953.

SPIN90, an adaptor protein, alters the proximity between Rab5 and Gapex5 and facilitates Rab5 activation during EGF endocytosis

During ligand-mediated receptor endocytosis, the small GTPase Rab5 functions in vesicle fusion and trafficking. Rab5 activation is known to require interactions with its guanine nucleotide-exchange factors (GEFs); however, the mechanism regulating Rab5 interactions with GEFs remains unclear. Here, we show that the SH3-adapter protein SPIN90 participates in the activation of Rab5 through the recruitment of both Rab5 and its GEF, Gapex5, to endosomal membranes during epidermal growth factor (EGF)-mediated endocytosis. SPIN90 strongly interacts with the inactive Rab5/GDI2 complex through its C-terminus. In response to EGF signaling, extracellular signal-regulated kinase (ERK)-mediated phosphorylation of SPIN90 at Thr-242 enables SPIN90 to bind Gapex5 through its N-terminal SH3 domain. Gapex5 is a determinant of Rab5 membrane targeting, while SPIN90 mediates the interaction between Gapex5 and Rab5 in a phosphorylation-dependent manner. Collectively, our findings suggest that SPIN90, as an adaptor protein, simultaneously binds inactive Rab5 and Gapex5, thereby altering their spatial proximity and facilitating Rab5 activation.

Cortactin promotes exosome secretion by controlling branched actin dynamics

Sinha et al. show that the cytoskeletal and tumor-overexpressed protein cortactin promotes secretion of exosomes from cancer cells by stabilizing dynamic cortical actin docking sites for multivesicular endosomes, suggesting a potential mechanism by which cortactin may promote tumor aggressiveness.

Exosomes are extracellular vesicles that influence cellular behavior and enhance cancer aggressiveness by carrying bioactive molecules. The mechanisms that regulate exosome secretion are poorly understood. Here, we show that the actin cytoskeletal regulatory protein cortactin promotes exosome secretion. Knockdown or overexpression of cortactin in cancer cells leads to a respective decrease or increase in exosome secretion, without altering exosome cargo content. Live-cell imaging revealed that cortactin controls both trafficking and plasma membrane docking of multivesicular late endosomes (MVEs). Regulation of exosome secretion by cortactin requires binding to the branched actin nucleating Arp2/3 complex and to actin filaments. Furthermore, cortactin, Rab27a, and coronin 1b coordinately control stability of cortical actin MVE docking sites and exosome secretion. Functionally, the addition of purified exosomes to cortactin-knockdown cells rescued defects of those cells in serum-independent growth and invasion. These data suggest a model in which cortactin promotes exosome secretion by stabilizing cortical actin-rich MVE docking sites.

KRAS-MEK Signaling Controls Ago2 Sorting into Exosomes

Secretion of RNAs in extracellular vesicles is a newly recognized form of intercellular communication. A potential regulatory protein for microRNA (miRNA) secretion is the critical RNA-induced silencing complex (RISC) component Argonaute 2 (Ago2). Here, we use isogenic colon cancer cell lines to show that overactivity of KRAS due to mutation inhibits localization of Ago2 to multivesicular endosomes (MVEs) and decreases Ago2 secretion in exosomes. Mechanistically, inhibition of mitogen-activated protein kinase kinases (MEKs) I and II, but not Akt, reverses the effect of the activating KRAS mutation and leads to increased Ago2-MVE association and increased exosomal secretion of Ago2. Analysis of cells expressing mutant Ago2 constructs revealed that phosphorylation of Ago2 on serine 387 prevents Ago2-MVE interactions and reduces Ago2 secretion into exosomes. Furthermore, regulation of Ago2 exosomal sorting controls the levels of three candidate miRNAs in exosomes. These data identify a key regulatory signaling event that controls Ago2 secretion in exosomes.

PI(3,5)P2 controls endosomal branched actin dynamics by regulating cortactin-actin interactions

The late endosomal lipid PI(3,5)P₂ binds to cortactin through the filamentous actin (F-actin) binding domain of cortactin, leading to removal of cortactin from endosomal actin networks and inhibition of cortactin-mediated branched actin nucleation and stabilization.

Branched actin critically contributes to membrane trafficking by regulating membrane curvature, dynamics, fission, and transport. However, how actin dynamics are controlled at membranes is poorly understood. Here, we identify the branched actin regulator cortactin as a direct binding partner of phosphatidylinositol 3,5-bisphosphate (PI(3,5)P₂) and demonstrate that their interaction promotes turnover of late endosomal actin. In vitro biochemical studies indicated that cortactin binds PI(3,5)P₂ via its actin filament-binding region. Furthermore, PI(3,5)P₂ competed with actin filaments for binding to cortactin, thereby antagonizing cortactin activity. These findings suggest that PI(3,5)P₂ formation on endosomes may remove cortactin from endosome-associated branched actin. Indeed, inhibition of PI(3,5)P₂ production led to cortactin accumulation and actin stabilization on Rab7⁺ endosomes. Conversely, inhibition of Arp2/3 complex activity greatly reduced cortactin localization to late endosomes. Knockdown of cortactin reversed PI(3,5)P₂-inhibitor–induced actin accumulation and stabilization on endosomes. These data suggest a model in which PI(3,5)P₂ binding removes cortactin from late endosomal branched actin networks and thereby promotes net actin turnover.

SPIN90 knockdown attenuates the formation and movement of endosomal vesicles in the early stages of epidermal growth factor receptor endocytosis

The finding that SPIN90 colocalizes with epidermal growth factor (EGF) in EEA1-positive endosomes prompted us to investigate the role of SPIN90 in endocytosis of the EGF receptor (EGFR). In the present study, we demonstrated that SPIN90 participates in the early stages of endocytosis, including vesicle formation and trafficking. Stable HeLa cells with knockdown of SPIN90 displayed significantly higher levels of surface EGFR than control cells. Analysis of the abundance and cellular distribution of EGFR via electron microscopy revealed that SPIN90 knockdown cells contain residual EGFR at cell membranes and fewer EGFR-containing endosomes, both features that reflect reduced endosome formation. The delayed early endosomal targeting capacity of SPIN90 knockdown cells led to increased EGFR stability, consistent with the observed accumulation of EGFR at the membrane. Small endosome sizes and reduced endosome formation in SPIN90 knockdown cells, observed using fluorescent confocal microscopy, strongly supported the involvement of SPIN90 in endocytosis of EGFR. Overexpression of SPIN90 variants, particularly the SH3, PRD, and CC (positions 643 - 722) domains, resulted in aberrant morphology of Rab5-positive endosomes (detected as small spots located near the cell membrane) and defects in endosomal movement. These findings clearly suggest that SPIN90 participates in the formation and movement of endosomes. Consistent with this, SPIN90 knockdown enhanced cell proliferation. The delay in EGFR endocytosis effectively increased the levels of endosomal EGFR, which triggered activation of ERK1/2 and cell proliferation via upregulation of cyclin D1. Collectively, our findings suggest that SPIN90 contributes to the formation and movement of endosomal vesicles, and modulates the stability of EGFR protein, which affects cell cycle progression via regulation of the activities of downstream proteins, such as ERK1/2, after EGF stimulation.

Regulation of late endosomal/lysosomal maturation and trafficking by cortactin affects Golgi morphology

Cortactin is a branched actin regulator and tumor-overexpressed protein that promotes vesicular trafficking at a variety of cellular sites, including endosomes and the trans-Golgi network. To better understand its role in secretory trafficking, we investigated its function in Golgi homeostasis. Here, we report that knockdown (KD) of cortactin leads to a dramatic change in Golgi morphology by light microscopy, dependent on binding the Arp2/3 actin-nucleating complex. Surprisingly, there was little effect of cortactin-KD on anterograde trafficking of the constitutive cargo vesicular stomatitis virus glycoprotein (VSVG), Golgi assembly from endoplasmic reticulum membranes upon Brefeldin A washout, or Golgi ultrastructure. Instead, electron microscopy studies revealed that cortactin-KD cells contained a large number of immature-appearing late endosomal/lysosomal (LE/Lys) hybrid organelles, similar to those found in lysosomal storage diseases. Consistent with a defect in LE/Lys trafficking, cortactin-KD cells also exhibited accumulation of free cholesterol and retention of the retrograde Golgi cargo mannose-6-phosphate receptor in LE. Inhibition of LE maturation by treatment of control cells with Rab7 siRNA or chloroquine led to a compact Golgi morphology similar to that observed in cortactin-KD cells. Furthermore, the Golgi morphology defects of cortactin-KD cells could be rescued by removal of cholesterol-containing lipids from the media, suggesting that buildup of cholesterol-rich membranes in immature LE/Lys induced disturbances in retrograde trafficking. Taken together, these data reveal that LE/Lys maturation and trafficking are highly sensitive to cortactin-regulated branched actin assembly and suggests that cytoskeletal-induced Golgi morphology changes can be a consequence of altered trafficking at late endosomes.

Anti-inflammatory mechanism of intravascular neural stem cell transplantation in haemorrhagic stroke

Neural stem cell (NSC) transplantation has been investigated as a means to reconstitute the damaged brain after stroke. In this study, however, we investigated the effect on acute cerebral and peripheral inflammation after intracerebral haemorrhage (ICH). NSCs (H1 clone) from fetal human brain were injected intravenously (NSCs-iv, 5 million cells) or intracerebrally (NSCs-ic, 1 million cells) at 2 or 24 h after collagenase-induced ICH in a rat model. Only NSCs-iv-2 h resulted in fewer initial neurologic deteriorations and reduced brain oedema formation, inflammatory infiltrations (OX-42, myeloperoxidase) and apoptosis (activated caspase-3, TUNEL) compared to the vehicle-injected control animals. Rat neurosphere-iv-2 h, but not human fibroblast-iv-2 h, also reduced the brain oedema and the initial neurologic deficits. Human NSCs-iv-2 h also attenuated both cerebral and splenic activations of tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and nuclear factor-kappa B (NF-kappaB). However, we observed only a few stem cells in brain sections of the NSCs-iv-2 h group; in the main, they were detected in marginal zone of spleens. To investigate whether NSCs interact with spleen to reduce cerebral inflammation, we performed a splenectomy prior to ICH induction, which eliminated the effect of NSCs-iv-2 h transplantation on brain water content and inflammatory infiltrations. NSCs also inhibited in vitro macrophage activations after lipopolysaccharide stimulation in a cell-to-cell contact dependent manner. In summary, early intravenous NSC injection displayed anti-inflammatory functionality that promoted neuroprotection, mainly by interrupting splenic inflammatory responses after ICH.

Systemic transplantation of human adipose stem cells attenuated cerebral inflammation and degeneration in a hemorrhagic stroke model

Adipose-derived stem cells (ASCs) are readily accessible multipotent mesenchymal stem cells and are known to secrete multiple growth factors, and thereby to have cytoprotective effects in various injury models. In the present study, the authors investigated the neuroprotective effect of ASCs in an intracerebral hemorrhage (ICH) model. ICH was induced via the stereotaxic infusion of collagenase, and human ASCs (three million cells per animal) isolated from human fresh fat tissue, were intravenously administered at 24 h post-ICH induction. Acute brain inflammation markers, namely, cell numbers positively stained for terminal transferase dUTP nick end labeling (TUNEL), myeloperoxidase (MPO), or OX-42, and brain water content were checked at 3 days post-ICH. In addition, the authors quantified brain degeneration by measuring hemispheric atrophy and perihematomal glial thickness at 6 weeks post-ICH, and determined modified limb placing behavioral scores weekly over 5 weeks post-ICH. The results showed that brain water content, TUNEL+, and MPO+ cell numbers were significantly reduced in the ASC-transplanted rats. ASC transplantation attenuated neurological deficits from 4 to 5 weeks post-ICH, and reduced both the brain atrophy and the glial proliferation at 6 weeks. Transplanted ASCs were found to densely populate perihematomal areas at 6 weeks, and to express endothelial markers (von Willebrand factor and endothelial barrier antigen), but not neuronal or glial markers. In summary, ASCs transplantation in the ICH model reduced both acute cerebral inflammation and chronic brain degeneration, and promoted long-term functional recovery.

Interaction of SPIN90 with syndapin is implicated in clathrin-mediated endocytic pathway in fibroblasts

SPIN90, a 90-kDa Nck-interacting protein with a SH3 domain, plays a role in sarcomere formation and myofibril assembly, and its phosphorylation is modulated by cell adhesion and Erk activation. Here we demonstrate that SPIN90 participates in receptor-mediated endocytic pathway in fibroblasts. We identified syndapin (synaptic dynamin-binding protein) as a SPIN90 interacting protein using yeast two-hybrid screening. SPIN90 directly binds the SH3 domain of syndapin via its proline rich domain in vitro and in vivo and also associates with clathrin. Over-expression of SPIN90-full length in COS-7 cells inhibited transferrin uptake, a marker of endocytosis. Interestingly, SPIN90-PRD, a syndapin-binding domain, significantly inhibited endocytosis, and the inhibition was reversed by co-expression of syndapin. Depleting SPIN90 through antibody microinjection or Knocking it down using siRNAs also significantly inhibited transferrin internalization. Moreover, early endosomal marker proteins (EEA1 and Rab5) appeared to closely associate or partially co-localize with SPIN90 in endosomes and an internalized FITC-dextran and Texas Red-EGF were found on the endosomes in association with SPIN90. Time-lapse video showed that GFP-SPIN90 travels with moving vesicles within living cells. Taken together, these findings suggest that SPIN90 is implicated in receptor-mediated endocytic pathway in fibroblasts.