In Situ Photo-Crosslinkable Protein Bioadhesive for Bone Graft Fixation

Bone grafting is a fundamental dental surgery procedure widely used for implant placement and periodontal disease management treatments. Despite its broad applications, vertical bone augmentation presents unique challenges, including the risk of graft displacement due to gravitational and masticatory forces. Traditional physical stabilization methods introduce additional complexities and risks, underscoring the need for innovative fixation technologies. This study aimed to develop an in situ photo-crosslinkable bioadhesive hydrogel (iPBAH) as a multifunctional bone graft binder to enhance the process of bone reconstruction. The bioadhesive is composed of mussel-derived adhesive protein (MAP) fused with the cell-adhesive peptide RGD. The numerous tyrosine residues in MAP facilitate rapid photo-crosslinking, enabling efficient hydrogel formation using visible blue light. Subsequently, iPBAH underwent comprehensive characterization to evaluate its suitability as a multifunctional bone graft binder. iPBAH efficiently underwent in situ crosslinking through harmless exposure to visible light within minutes and displayed several exceptional properties, including a microporous structure, underwater adhesion, extended durability, high compressive strength, and biocompatibility. In vivo assessments, using male Sprague-Dawley rats, demonstrated that iPBAH binder significantly enhanced bone regeneration in a rat calvarial bone defect model. The in situ crosslinking of the iPBAH binder during bone graft transplantation can effectively fill irregular and complex defect shapes while simultaneously preventing graft material leakage. The improved physical attributes of the bound graft material can enhance its resistance to external forces, thereby ensuring sustained retention over time. Moreover, the interaction between iPBAH and surrounding tissues promotes adhesion and integration of the graft material with host tissues in the defect area. In addition, the included RGD peptide in iPBAH can augment inherent cell recruitment, adhesion, and growth, consequently expediting osteogenesis.

Crosstalk between Signaling Pathways and Energy Metabolism in Pluripotency

The sequential change from totipotency to multipotency occurs during early mammalian embryo development. However, due to the lack of cellular models to recapitulate the distinct potency of stem cells at each stage, their molecular and cellular characteristics remain ambiguous. The establishment of isogenic naïve and primed pluripotent stem cells to represent the pluripotency in the inner cell mass of the pre-implantation blastocyst and in the epiblast from the post-implantation embryo allows the understanding of the distinctive characteristics of two different states of pluripotent stem cells. This review discusses the prominent disparities between naïve and primed pluripotency, including signaling pathways, metabolism, and epigenetic status, ultimately facilitating a comprehensive understanding of their significance during early mammalian embryonic development.

Epigenetic repression of CHCHD2 enhances survival from single cell dissociation through attenuated Rho A kinase activity

During in vitro culture, human pluripotent stem cells (hPSCs) often acquire survival advantages characterized by decreased susceptibility to mitochondrial cell death, known as "culture adaptation." This adaptation is associated with genetic and epigenetic abnormalities, including TP53 mutations, copy number variations, trisomy, and methylation changes. Understanding the molecular mechanisms underlying this acquired survival advantage is crucial for safe hPSC-based cell therapies. Through transcriptome and methylome analysis, we discovered that the epigenetic repression of CHCHD2, a mitochondrial protein, is a common occurrence during in vitro culture using enzymatic dissociation. We confirmed this finding through genetic perturbation and reconstitution experiments in normal human embryonic stem cells (hESCs). Loss of CHCHD2 expression conferred resistance to single cell dissociation-induced cell death, a common stress encountered during in vitro culture. Importantly, we found that the downregulation of CHCHD2 significantly attenuates the activity of Rho-associated protein kinase (ROCK), which is responsible for inducing single cell death in hESCs. This suggests that hESCs may survive routine enzyme-based cell dissociation by downregulating CHCHD2 and thereby attenuating ROCK activity. These findings provide insights into the mechanisms by which hPSCs acquire survival advantages and adapt to in vitro culture conditions.

Partial in vivo reprogramming enables injury-free intestinal regeneration via autonomous Ptgs1 induction

Tissue regeneration after injury involves the dedifferentiation of somatic cells, a natural adaptive reprogramming that leads to the emergence of injury-responsive cells with fetal-like characteristics. However, there is no direct evidence that adaptive reprogramming involves a shared molecular mechanism with direct cellular reprogramming. Here, we induced dedifferentiation of intestinal epithelial cells using OSKM (Oct4, Sox2, Klf4, and c-Myc) in vivo. The OSKM-induced forced dedifferentiation showed similar molecular features of intestinal regeneration, including a transition from homeostatic cell types to injury-responsive-like cell types. These injury-responsive-like cells, sharing gene signatures of revival stem cells and atrophy-induced villus epithelial cells, actively assisted tissue regeneration following damage. In contrast to normal intestinal regeneration involving Ptgs2 induction, the OSKM promotes autonomous production of prostaglandin E2 via epithelial Ptgs1 expression. These results indicate prostaglandin synthesis is a common mechanism for intestinal regeneration but involves a different enzyme when partial reprogramming is applied to the intestinal epithelium.

In Silico Discovery of 5'-Modified 7-Deoxy-7-ethynyl-4'-thioadenosine as a HASPIN Inhibitor and Its Synergistic Anticancer Effect with the PLK1 Inhibitor

Despite genetic perturbations resulting in embryo lethality for most mitotic kinases, loss of the histone H3 mitotic kinase HASPIN reveals no adverse effect in mice models, establishing HASPIN as a promising target for anticancer therapy. However, developing a HASPIN inhibitor from conventional pharmacophores poses a technical challenge as this atypical kinase shares slight similarities with eukaryotic protein kinases. Chemically modifying a cytotoxic 4'-thioadenosine analogue through high genotoxicity yielded several novel nongenotoxic kinase inhibitors. In silico apporoaches utilizing transcriptomic and chemical similarities with known compounds and KINOMEscan profiles unveiled the HASPIN inhibitor LJ4827. LJ4827's specificity and potency as a HASPIN inhibitor were verified through in vitro kinase assay and X-ray crystallography. HASPIN inhibition by LJ4827 reduced histone H3 phosphorylation and impeded Aurora B recruitment in cancer cell centromeres but not in noncancer cells. Through transcriptome analysis of lung cancer patients, PLK1 was determined as a druggable synergistic partner to complement HASPIN inhibition. Chemical or genetic PLK1 perturbation with LJ4827 effectuated pronounced lung cancer cytotoxicity in vitro and in vivo. Therefore, LJ4827 is a novel anticancer therapeutic for selectively impeding cancer mitosis through potent HASPIN inhibition, and simultaneous HASPIN and PLK1 interference is a promising therapeutic strategy for lung cancer.

Gene editing with 'pencil' rather than 'scissors' in human pluripotent stem cells

Owing to the advances in genome editing technologies, research on human pluripotent stem cells (hPSCs) have recently undergone breakthroughs that enable precise alteration of desired nucleotide bases in hPSCs for the creation of isogenic disease models or for autologous ex vivo cell therapy. As pathogenic variants largely consist of point mutations, precise substitution of mutated bases in hPSCs allows researchers study disease mechanisms with "disease-in-a-dish" and provide functionally repaired cells to patients for cell therapy. To this end, in addition to utilizing the conventional homologous directed repair system in the knock-in strategy based on endonuclease activity of Cas9 (i.e., 'scissors' like gene editing), diverse toolkits for editing the desirable bases (i.e., 'pencils' like gene editing) that avoid the accidental insertion and deletion (indel) mutations as well as large harmful deletions have been developed. In this review, we summarize the recent progress in genome editing methodologies and employment of hPSCs for future translational applications.

MutSα and MutSβ as size-dependent cellular determinants for prime editing in human embryonic stem cells

Precise genome editing in human pluripotent stem cells (hPSCs) has potential applications in isogenic disease modeling and ex vivo stem cell therapy, necessitating diverse genome editing tools. However, unlike differentiated somatic cells, hPSCs have unique cellular properties that maintain genome integrity, which largely determine the overall efficiency of an editing tool. Considering the high demand for prime editors (PEs), it is imperative to characterize the key molecular determinants of PE outcomes in hPSCs. Through homozygous knockout (KO) of MMR pathway key proteins MSH2, MSH3, and MSH6, we reveal that MutSα and MutSβ determine PE efficiency in an editing size-dependent manner. Notably, MSH2 perturbation disrupted both MutSα and MutSβ complexes, dramatically escalating PE efficiency from base mispair to 10 bases, up to 50 folds. Similarly, impaired MutSα by MSH6 KO improved editing efficiency from single to three base pairs, while defective MutSβ by MSH3 KO heightened efficiency from three to 10 base pairs. Thus, the size-dependent effect of MutSα and MutSβ on prime editing implies that MMR is a vital PE efficiency determinant in hPSCs and highlights the distinct roles of MutSα and MutSβ in its outcome.

Transition Substitution of Desired Bases in Human Pluripotent Stem Cells with Base Editors: A Step-by-Step Guide

The recent advances in human pluripotent stem cells (hPSCs) enable to precisely edit the desired bases in hPSCs to be used for the establishment of isogenic disease models and autologous ex vivo cell therapy. The knock-in approach based on the homologous directed repair with Cas9 endonuclease, causing DNA double-strand breaks (DSBs), produces not only insertion and deletion (indel) mutations but also deleterious large deletions. On the contrary, due to the lack of Cas9 endonuclease activity, base editors (BEs) such as adenine base editor (ABE) and cytosine base editor (CBE) allow precise base substitution by conjugated deaminase activity, free from DSB formation. Despite the limitation of BEs in transition substitution, precise base editing by BEs with no massive off-targets is suggested to be a prospective alternative in hPSCs for clinical applications. Considering the unique cellular characteristics of hPSCs, a few points should be considered. Herein, we describe an updated and optimized protocol for base editing in hPSCs. We also describe an improved methodology for CBE-based C to T substitutions, which are generally lower than A to G substitutions in hPSCs.

Label-free and non-destructive identification of naïve and primed embryonic stem cells based on differences in cellular metabolism

Pluripotent stem cells (PSCs) exist in naïve or primed states based on their origin. For in vitro culture, these PSCs require different supplements and growth factors. However, owing to their similar phenotypic features, identifying both cell types without harming cellular functions is challenging. This study reports an electrochemical method that enables simple, label-free, and non-destructive detection of naïve embryonic stem cells (ESCs) derived from mouse ESCs, based on the differences in cellular metabolism. Two major metabolic pathways to generate adenosine triphosphate (ATP)-glycolysis and oxidative phosphorylation (OXPHOS)-were blocked, and it was found that mitochondrial energy generation is the origin of the strong electrochemical signals of naïve ESCs. The number of ESCs is quantified when mixed with primed ESCs or converted from naïve-primed switchable metastable ESCs. The mouse PSCs derived from doxycycline-inducible mouse embryonic fibroblasts (MEFs) are also sensitively identified among other cell types such as unconverted MEFs and primed PSCs. The developed sensing platform operates in a non-invasive and label-free manner. Thus, it can be useful in the development of stem cell-derived therapeutics.

TPX2 prompts mitotic survival via the induction of BCL2L1 through YAP1 protein stabilization in human embryonic stem cells

Genetic alterations have been reported for decades in most human embryonic stem cells (hESCs). Survival advantage, a typical trait acquired during long-term in vitro culture, results from the induction of BCL2L1 upon frequent copy number variation (CNV) at locus 20q11.21 and is one of the strongest candidates associated with genetic alterations that occur via escape from mitotic stress. However, the underlying mechanisms for BCL2L1 induction remain unknown. Furthermore, abnormal mitosis and the survival advantage that frequently occur in late passage are associated with the expression of BCL2L1, which is in locus 20q11.21. In this study, we demonstrated that the expression of TPX2, a gene located in 20q11.21, led to BCL2L1 induction and consequent survival traits under mitotic stress in isogenic pairs of hESCs and human induced pluripotent stem cells (iPSCs) with normal and 20q11.21 CNVs. High Aurora A kinase activity by TPX2 stabilized the YAP1 protein to induce YAP1-dependent BCL2L1 expression. A chemical inhibitor of Aurora A kinase and knockdown of YAP/TAZ significantly abrogated the high tolerance to mitotic stress through BCL2L1 suppression. These results suggest that the collective expression of TPX2 and BCL2L1 from CNV at loci 20q11.21 and a consequent increase in YAP1 signaling promote genome instability during long-term in vitro hESC culture.

The Korean undiagnosed diseases program phase I: expansion of the nationwide network and the development of long-term infrastructure

BACKGROUND

Phase I of the Korean Undiagnosed Diseases Program (KUDP), performed for 3 years, has been completed. The Phase I program aimed to solve the problem of undiagnosed patients throughout the country and develop infrastructure, including a data management system and functional core laboratory, for long-term translational research. Herein, we share the clinical experiences of the Phase I program and introduce the activities of the functional core laboratory and data management system.

RESULTS

During the program (2018-2020), 458 patients were enrolled and classified into 3 groups according to the following criteria: (I) those with a specific clinical assessment which can be verified by direct testing (32 patients); (II) those with a disease group with genetic and phenotypic heterogeneity (353 patients); and (III) those with atypical presentations or diseases unknown to date (73 patients). All patients underwent individualized diagnostic processes based on the decision of an expert consortium. Confirmative diagnoses were obtained for 242 patients (52.8%). The diagnostic yield was different for each group: 81.3% for Group I, 53.3% for Group II, and 38.4% for Group III. Diagnoses were made by next-generation sequencing for 204 patients (84.3%) and other genetic testing for 35 patients (14.5%). Three patients (1.2%) were diagnosed with nongenetic disorders. The KUDP functional core laboratory, with a group of experts, organized a streamlined research pipeline covering various resources, including animal models, stem cells, structural modeling and metabolic and biochemical approaches. Regular data review was performed to screen for candidate genes among undiagnosed patients, and six different genes were identified for functional research. We also developed a web-based database system that supports clinical cohort management and provides a matchmaker exchange protocol based on a matchbox, likely to reinforce the nationwide clinical network and further international collaboration.

CONCLUSIONS

The KUDP evaluated the unmet needs of undiagnosed patients and established infrastructure for a data-sharing system and future functional research. The advancement of the KUDP may lead to sustainable bench-to-bedside research in Korea and contribute to ongoing international collaboration.

Dichotomous role of Shp2 for naïve and primed pluripotency maintenance in embryonic stem cells

Background

The requirement of the Mek1 inhibitor (iMek1) during naïve pluripotency maintenance results from the activation of the Mek1-Erk1/2 (Mek/Erk) signaling pathway upon leukemia inhibitory factor (LIF) stimulation.

Methods

Through a meta-analysis of previous genome-wide screening for negative regulators of naïve pluripotency, Ptpn11 (encoding the Shp2 protein, which serves both as a tyrosine phosphatase and putative adapter), was predicted as one of the key factors for the negative modulation of naïve pluripotency through LIF-dependent Jak/Stat3 signaling. Using an isogenic pair of naïve and primed mouse embryonic stem cells (mESCs), we demonstrated the differential role of Shp2 in naïve and primed pluripotency.

Results

Loss of Shp2 increased naïve pluripotency by promoting Jak/Stat3 signaling and disturbed in vivo differentiation potential. In sharp contrast, Shp2 depletion significantly impeded the self-renewal of ESCs under primed culture conditions, which was concurrent with a reduction in Mek/Erk signaling. Similarly, upon treatment with an allosteric Shp2 inhibitor (iShp2), the cells sustained Stat3 phosphorylation and decoupled Mek/Erk signaling, thus iShp2 can replace the use of iMek1 for maintenance of naïve ESCs.

Conclusions

Taken together, our findings highlight the differential roles of Shp2 in naïve and primed pluripotency and propose the usage of iShp2 instead of iMek1 for the efficient maintenance and establishment of naïve pluripotency.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02976-z.

Abstract 71: Integrated-omics analysis identifies the druggable achilles targets to sensitize cancer cells with gefitinib resistance

Limited eligibility remains one of major drawbacks of target therapeutics as the oncogenic dependency is only determined by mutation status of a target. In order to extend the eligibility of target therapeutics, transcriptome profiles of patients have been examined to better delineate sensitivity of target therapeutics. In this study, we took advantage of multiple large datasets such as cancer cell line transcriptome data (CCLE), drug response data (CTRP), and gene dependency data (Achilles Project) to determine the sensitivity markers of tyrosine kinase inhibitors currently approved by FDA. In particular, EGFR inhibitors (iEGFR: lapatinib, gefitinib and erlotinib) revealed clear sensitivity cluster of cell line regardless of EGFR mutation status. Comparative analysis between sensitive (iEGFR-S) and resistant (iEGFR-R) cell groups revealed that integrated gene signatures such as chemokine, GPCR, and PI3K-Akt signaling pathway, were predicted as putative determinants of iEGFR susceptibility. Through integrated analysis of gene dependency data, among several Achilles’ targets (of which depletion increases vulnerability), predicted in iEGFR-R cells group, druggable Achilles’ targets (available to accompanied drugs) such as CCR6, AURKA and mTOR were identified as putative targets for sensitizing iEGFR-R group to iEGFR. Following biochemical studies validated the clear sensitizing effect of the pharmacological inhibitor for each predicted target, in the isogenic cell models with acquired iEGFR resistance. In addition, prediction and following biochemical validation, we demonstrated that the CCR6 inhibition significantly attenuated resistance of iEGFR by repressing mitochondrial ROS (mt-ROS), of which induction by iEGFR rescued cell death. These data suggest that integrated-omics analysis would be a useful approach to extend eligibility and improve the efficacy of target therapeutics.

Citation Format: Eun-Ji Kwon, Haeseung Lee, Hyuk-Jin Cha. Integrated-omics analysis identifies the druggable achilles targets to sensitize cancer cells with gefitinib resistance [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 71.

Abstract 3949: Identification of a novel HASPIN inhibitor and the synthetic lethal partner by computational analysis

HASPIN, a mitotic kinase to phosphorylate Histone H3 at centromere, has been studied as a promising target for anti-cancer therapy. However, as HASPIN belongs to atypical kinase, lacking the Asp-Phe-Gly (DFG) motif, development from the chemical library of kinase inhibitors with conventional pharmacophore, would be technically challenging. In particular, one of adenosine analogues (LJ4827), a potent inhibitor of multi-kinases, showing clear anti-cancer activity in vitro and in vivo, was predicted as a HASPIN inhibitor by computation analysis of its transcriptome profile in cancer cells to drug-omic data set in the connectivity MAP (cMAP) as it shared similar transcriptome profile of 5-iodotubercidin (5ITU). The specificity and potency as HASPIN inhibitor of LJ4827 (IC50 = 0.45 nM) validated by in vitro kinase screening and consequent 3D structure modeling. As expected, treatment of LJ4827 in cancer cell lines efficiently delayed mitotic progression without double strand break (DSB) unlike 5ITU and significantly attenuated Aurora B localization at centromere. Along with clinical significance of HASPIN expression in lung cancer patients, mitotic gene signature closely associated to high expression of HASPIN, revealed the poor prognosis. Additional computational analysis of kinase perturbation data to predict the dependency of mitotic kinase in the absence of HASPIN activity, revealed the synthetic lethal effect of cotreatment of the chemical inhibitor of BUB1, PLK1 or AURKA with LJ4827. These data suggest that combined inhibition of HASPIN with the novel inhibitor and key mitotic kinases for centromere/kinetochore regulation would be effectivity therapeutic approach for cancer therapy.

Citation Format: Eun-Ji Kwon, Karishma Mashelkar, Hyuk Woo Lee, Yoon-Ze Shin, Lak Shin Jeong, Hyuk-Jin Cha. Identification of a novel HASPIN inhibitor and the synthetic lethal partner by computational analysis [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 3949.

High expression of uracil DNA glycosylase determines C to T substitution in human pluripotent stem cells

Precise genome editing of human pluripotent stem cells (hPSCs) is crucial not only for basic science but also for biomedical applications such as ex vivo stem cell therapy and genetic disease modeling. However, hPSCs have unique cellular properties compared to somatic cells. For instance, hPSCs are extremely susceptible to DNA damage, and therefore Cas9-mediated DNA double-strand breaks (DSB) induce p53-dependent cell death, resulting in low Cas9 editing efficiency. Unlike Cas9 nucleases, base editors including cytosine base editor (CBE) and adenine base editor (ABE) can efficiently substitute single nucleotides without generating DSBs at target sites. Here, we found that the editing efficiency of CBE was significantly lower than that of ABE in human embryonic stem cells (hESCs), which are associated with high expression of DNA glycosylases, the key component of the base excision repair pathway. Sequential depletion of DNA glycosylases revealed that high expression of uracil DNA glycosylase (UNG) not only resulted in low editing efficiency but also affected CBE product purity (i.e., C to T) in hESCs. Therefore, additional suppression of UNG via transient knockdown would also improve C to T base substitutions in hESCs. These data suggest that the unique cellular characteristics of hPSCs could determine the efficiency of precise genome editing.

Target identification of mouse stem cell probe CDy1 as ALDH2 and Abcb1b through live-cell affinity-matrix and ABC CRISPRa library

CDy1 is a powerful tool to distingusih embryonic stem cells for reprogramming studies and regeneration medicine. However, the stem cell selectivity mechanism of CDy1 has not been fully understood. Here, we report ALDH2 and ABCB1 as the molecular targets of CDy1, elucidated by live-cell affinity-matrix and ABC transporter CRISPRa library screening. The two unique orthogonal mechanisms provide the potential of multi-demensional cellular distinction of specific cell types.

CDy1 is a powerful tool to distingusih embryonic stem cells for reprogramming studies and regeneration medicine.

Editorial Expression of Concern: Tumor necrosis factor-inducible gene 6 protein ameliorates chronic liver damage by promoting autophagy formation in mice

An Editorial Expression of Concern to this paper has been published: https://doi.org/10.1038/s12276-021-00554-6

L1 retrotransposons exploit RNA m6A modification as an evolutionary driving force

L1 retrotransposons can pose a threat to genome integrity. The host has evolved to restrict L1 replication. However, mechanisms underlying L1 propagation out of the host surveillance remains unclear. Here, we propose an evolutionary survival strategy of L1, which exploits RNA m⁶A modification. We discover that m⁶A 'writer' METTL3 facilitates L1 retrotransposition, whereas m⁶A 'eraser' ALKBH5 suppresses it. The essential m⁶A cluster that is located on L1 5' UTR serves as a docking site for eukaryotic initiation factor 3 (eIF3), enhances translational efficiency and promotes the formation of L1 ribonucleoprotein. Furthermore, through the comparative analysis of human- and primate-specific L1 lineages, we find that the most functional m⁶A motif-containing L1s have been positively selected and became a distinctive feature of evolutionarily young L1s. Thus, our findings demonstrate that L1 retrotransposons hijack the RNA m⁶A modification system for their successful replication.

Crosstalk between YAP and TGFβ regulates SERPINE1 expression in mesenchymal lung cancer cells

Serpin family E member 1 (SERPINE1), a serine proteinase inhibitor, serves as an important regulator of extracellular matrix remodeling. Emerging evidence suggests that SERPINE1 has diverse roles in cancer and is associated with poor prognosis. However, the mechanism via which SERPINE1 is induced in cancer has not been fully determined. In order to examine the molecular mechanism of SERPINE1 expression, the present study took advantage of the isogenic pair of lung cancer cells with epithelial or mesenchymal features. Using genetic perturbation and following biochemical analysis, the present study demonstrated that SERPINE1 expression was upregulated in mesenchymal lung cancer cells and promoted cellular invasiveness. Yes‑associated protein (YAP)‑dependent SERPINE1 expression was modulated by treatment with a Rho‑associated protein kinase inhibitor, Y27632. Moreover, TGFβ treatment supported YAP‑dependent SERPINE1 expression, and an enhanced TGFβ response in mesenchymal lung cancer cells promoted SERPINE1 expression. TGFβ‑mediated SERPINE1 expression was significantly attenuated by knockdown of YAP or transcriptional co‑activator with PDZ‑binding motif, suggesting that crosstalk between the TGFβ and YAP pathways underlies SERPINE1 expression in mesenchymal cancer cells.

Luteolin Induces Selective Cell Death of Human Pluripotent Stem Cells

Despite recent advances in clinical stem cell therapy applications based on human pluripotent stem cells (hPSCs), potential teratoma formation due to the presence of residual undifferentiated hPSCs remains a serious risk factor that challenges widespread clinical application. To overcome this risk, a variety of approaches have been developed to eliminate the remaining undifferentiated hPSCs via selective cell death induction. Our study seeks to identify natural flavonoids that are more potent than quercetin (QC), to selectively induce hPSC death. Upon screening in-house flavonoids, luteolin (LUT) is found to be more potent than QC to eliminate hPSCs in a p53-dependent manner, but not hPSC-derived smooth muscle cells or perivascular progenitor cells. Particularly, treating human embryonic stem cell (hESC)-derived cardiomyocytes with LUT efficiently eliminates the residual hESCs and only results in marginal effects on cardiomyocyte (CM) functions, as determined by calcium influx. Considering the technical limitations of isolating CMs due to a lack of exclusive surface markers at the end of differentiation, LUT treatment is a promising approach to minimize teratoma formation risk.

Systematic identification of a nuclear receptor-enriched predictive signature for erastin-induced ferroptosis

Erastin, a synthetic lethal compound against cancer expressing an oncogenic RAS, inhibits cystine/glutamate antiporters and causes ferroptosis. However, despite recent evidence for the mechanisms underlying ferroptosis, molecular biomarkers of erastin-dependent ferroptosis have not been identified. Here, we employed isogenic lung cancer cell models to show that a redox imbalance leads to glutathione depletion and ferroptosis. Subsequent transcriptome analysis of pan-cancer cell lines revealed that the activity of transcription factors, including NRF2 and AhR, serve as important markers of erastin resistance. Based on the integrated expression of genes in the nuclear receptor meta-pathway (NRM), we constructed an NRM model and validated its robustness using an independent pharmacogenomics dataset. The NRM model was further evaluated by sensitivity tests on nine cancer cell lines for which erastin sensitivities had not been determined. Our pharmacogenomics approach has the potential to pave the way for the efficient classification of patients for therapeutic intervention using erastin.

Safe scarless cassette-free selection of genome-edited human pluripotent stem cells using temporary drug resistance

An efficient gene-editing technique for use in human pluripotent stem cells (hPSCs) has great potential value in regenerative medicine, as well as in drug discovery based on isogenic human disease models. However, the extremely low efficiency of gene editing in hPSCs remains as a major technical hurdle. Previously, we demonstrated that YM155, a survivin inhibitor developed as an anti-cancer drug, induces highly selective cell death in undifferentiated hPSCs. In this study, we demonstrated that the high cytotoxicity of YM155 in hPSCs, which is mediated by selective cellular uptake of the drug, is due to the high expression of SLC35F2 in these cells. Knockout of SLC35F2 with CRISPR-Cas9, or depletion with siRNAs, made the hPSCs highly resistant to YM155. Simultaneous editing of a gene of interest and transient knockdown of SLC35F2 following YM155 treatment enabled the survival of genome-edited hPSCs as a result of temporary YM155 resistance, thereby achieving an enriched selection of clonal populations with gene knockout or knock-in. This precise and efficient genome editing approach took as little as 3 weeks and required no cell sorting or the introduction of additional genes, to be a more feasible approach for gene editing in hPSCs due to its simplicity.

Nuclear Factor Erythroid-Derived 2-Like 2-Induced Reductive Stress Favors Self-Renewal of Breast Cancer Stem-Like Cells via the FoxO3a-Bmi-1 Axis

Aims: A subpopulation of cancer cells, termed cancer stem cells (CSCs), has stemness properties, such as self-renewal and differentiation, which drive cancer recurrence and tumor resistance. CSCs possess enhanced protection capabilities to maintain reduced intracellular levels of reactive oxygen species (ROS) compared with nonstem-like cancer cells. This study investigated whether reductive stress could regulate self-renewal activity in breast CSCs. Results: We found that manifestation of stemness in breast cancer stem-like cells was associated with an elevated production of reduced glutathione (GSH) maintained by upregulation of glutamate cysteine ligase catalytic subunit (GCLC) and consequently, lowered ROS levels. This was accompanied by upregulation of phospho-AMP-activated protein kinase, FoxO3a, and Bmi-1. Notably, expression of nuclear factor erythroid-derived 2-like 2 (Nrf2) protein was substantially increased in cells undergoing sphere formation. We noticed that expression of Bmi-1 was inhibited after introduction of Nrf2 short interfering RNA into MCF-7 mammosphere cells. Silencing of Nrf2 expression suppressed the xenograft growth of subcutaneously or orthotopically injected human breast cancer cells. Innovation: Association between Nrf2 and self-renewal signaling in CSCs has been reported, but the underlying molecular mechanism remains largely unresolved. This study demonstrates the Nrf2-mediated signaling pathway in maintenance of reductive stress in breast CSCs. Conclusion: Nrf2 overactivation in breast CSCs upregulates GCLC expression and consequently enhances GSH biosynthesis with concurrent reduction in intracellular ROS accumulation, thereby provoking the reductive stress. The consequent upregulation of nuclear FoxO3a and its binding to the promoter of the gene encoding Bmi-1 account for the self-renewal activity of breast cancer stem-like cells and their growth in a xenograft mouse model.

Stochastic and Heterogeneous Cancer Cell Migration: Experiment and Theory

Cell migration, an essential process for normal cell development and cancer metastasis, differs from a simple random walk: the mean-square displacement (〈(Δr)²(t)〉) of cells sometimes shows non-Fickian behavior, and the spatiotemporal correlation function (G(r, t)) of cells is often non-Gaussian. We find that this intriguing cell migration should be attributed to heterogeneity in a cell population, even one with a homogeneous genetic background. There are two limiting types of heterogeneity in a cell population: cellular heterogeneity and temporal heterogeneity. Cellular heterogeneity accounts for the cell-to-cell variation in migration capacity, while temporal heterogeneity arises from the temporal noise in the migration capacity of single cells. We illustrate that both cellular and temporal heterogeneity need to be taken into account simultaneously to elucidate cell migration. We investigate the two-dimensional migration of A549 lung cancer cells using time-lapse microscopy and find that the migration of A549 cells is Fickian but has a non-Gaussian spatiotemporal correlation. We find that when a theoretical model considers both cellular and temporal heterogeneity, the model reproduces all of the anomalous behaviors of cancer cell migration.

Abstract 3799: Large-scale pharmacogenomics based drug discovery for ITGB3 dependent chemoresistance in mesenchymal lung cancer

Even when targets responsible for chemoresistance are identified, drug development is often hampered due to the poor druggability of these proteins. We systematically analyzed therapy-resistance with a large-scale cancer cell transcriptome and drug-response datasets and predicted the candidate drugs based on the gene expression profile. Our results implicated the epithelial-mesenchymal transition as a common mechanism underlying resistance to chemotherapeutic drugs. Notably, we identified ITGB3, whose expression was abundant in both drug resistance and mesenchymal status, as a promising target to overcome chemoresistance. We also confirmed that depletion of ITGB3 sensitized cancer cells to conventional chemotherapeutic drugs by modulating the NF-κB signaling pathway. Considering the poor druggability of ITGB3 and the lack of feasible drugs to directly inhibit this protein, we took an in silico screening for drugs mimicking the transcriptome-level changes caused by knockdown of ITGB3. This approach successfully identified atorvastatin as a novel candidate for drug repurposing, paving an alternative path to drug screening that is applicable to undruggable targets.

Citation Format: Haeseung Lee, Ok-Seon Kwon, Wankyu Kim, Hyuk-Jin Cha. Large-scale pharmacogenomics based drug discovery for ITGB3 dependent chemoresistance in mesenchymal lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3799.

Abstract 2002: Computational drug repositioning identifies bortezomib as a novel metastatic inhibitor of lung cancer

Although many molecular targets for cancer therapy have been discovered, they often show poor druggability, which is a major obstacle to develop targeted drugs. As an alternative route to drug discovery, we adopted an in silicodrug repositioning (in silicoDR) approach based on large-scale gene expression signatures, with the goal of identifying inhibitors of lung cancer metastasis. Our analysis of clinicogenomic data identified GALNT14, an enzyme involved in O-linked N-acetyl galactosamine glycosylation, as a putative driver of lung cancer metastasis leading to poor survival. To overcome the poor druggability of GALNT14, we leveraged Connectivity Map approach, an in silicoscreening for drugs that are likely to revert the metastatic expression patterns. It leads to identification of bortezomib (BTZ) as a potent metastatic inhibitor, bypassing direct inhibition of poorly druggable target, GALNT14. The anti-metastatic effect of BTZ was verified in vitroand in vivo. Notably, both BTZ treatment and GALNT14knockdown attenuated TGFβ-mediated gene expression and suppressed TGFβ-dependent metastatic genes, suggesting that BTZ acts by modulating TGFβsignaling. Taken together, these results demonstrate that our in silicoDR approach is a viable strategy to identify a candidate drug for undruggable targets, and to uncover its underlying mechanisms.

Citation Format: Ok-Seon Kwon, Haeseung Lee, Wankyu Kim, Hyuk-Jin Cha. Computational drug repositioning identifies bortezomib as a novel metastatic inhibitor of lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2002.

Structure-Activity Relationship Analysis of YM155 for Inducing Selective Cell Death of Human Pluripotent Stem Cells

Despite great potential for regenerative medicine, the high tumorigenic potential of human pluripotent stem cells (hPSCs) to form undesirable teratoma is an important technical hurdle preventing safe cell therapy. Various small molecules that induce the complete elimination of undifferentiated hPSCs, referred to as "stemotoxics," have been developed to facilitate tumor-free cell therapy, including the Survivin inhibitor YM155. In the present work, based on the chemical structure of YM155, total 26 analogs were synthesized and tested for stemotoxic activity toward human embryonic stem cells (hESCs) and induced PSCs (iPSCs). We found that a hydrogen bond acceptor in the pyrazine ring of YM155 derivatives is critical for stemotoxic activity, which is completely lost in hESCs lacking SLC35F2, which encodes a solute carrier protein. These results suggest that hydrogen bonding interactions between the nitrogens of the pyrazine ring and the SLC35F2 protein are critical for entry of YM155 into hPSCs, and hence stemotoxic activity.

Low dose radiation regulates BRAF-induced thyroid cellular dysfunction and transformation

Background

The existence of differentiated thyroid cells is critical to respond radioactive iodide treatment strategy in thyroid cancer, and loss of the differentiated phenotype is a trademark of iodide-refractive thyroid disease. While high-dose therapy has been beneficial to several cancer patients, many studies have indicated this clinical benefit was limited to patients having BRAF mutation. BRAF-targeted paired box gene-8 (PAX8), a thyroid-specific transcription factor, generally dysregulated in BRAF-mutated thyroid cancer.

Methods

In this study, thyroid iodine-metabolizing gene levels were detected in BRAF-transformed thyroid cells after low and high dose of ionizing radiation. Also, an mRNA-targeted approach was used to figure out the underlying mechanism of low (0.01Gyx10 or 0.1Gy) and high (2Gy) radiation function on thyroid cancer cells after BRAF^V600E mutation.

Results

Low dose radiation (LDR)-induced PAX8 upregulation restores not only BRAF-suppressive sodium/iodide symporter (NIS) expression, one of the major protein necessary for iodine uptake in healthy thyroid, on plasma membrane but also regulate other thyroid metabolizing genes levels. Importantly, LDR-induced PAX8 results in decreased cellular transformation in BRAF-mutated thyroid cells.

Conclusion

The present findings provide evidence that LDR-induced PAX8 acts as an important regulator for suppression of thyroid carcinogenesis through novel STAT3/miR-330-5p pathway in thyroid cancers.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0322-x) contains supplementary material, which is available to authorized users.

Large-scale pharmacogenomics based drug discovery for ITGB3 dependent chemoresistance in mesenchymal lung cancer

Even when targets responsible for chemoresistance are identified, drug development is often hampered due to the poor druggability of these proteins. We systematically analyzed therapy-resistance with a large-scale cancer cell transcriptome and drug-response datasets and predicted the candidate drugs based on the gene expression profile. Our results implicated the epithelial-mesenchymal transition as a common mechanism underlying resistance to chemotherapeutic drugs. Notably, we identified ITGB3, whose expression was abundant in both drug resistance and mesenchymal status, as a promising target to overcome chemoresistance. We also confirmed that depletion of ITGB3 sensitized cancer cells to conventional chemotherapeutic drugs by modulating the NF-κB signaling pathway. Considering the poor druggability of ITGB3 and the lack of feasible drugs to directly inhibit this protein, we took an in silico screening for drugs mimicking the transcriptome-level changes caused by knockdown of ITGB3. This approach successfully identified atorvastatin as a novel candidate for drug repurposing, paving an alternative path to drug screening that is applicable to undruggable targets.

Screening of cytotoxic or cytostatic flavonoids with quantitative Fluorescent Ubiquitination-based Cell Cycle Indicator-based cell cycle assay

The Fluorescent Ubiquitination-based Cell Cycle Indicator (FUCCI) system can be used not only to study gene expression at a specific cell cycle stage, but also to monitor cell cycle transitions in real time. In this study, we used a single clone of FUCCI-expressing HeLa cells (FUCCI-HeLa cells) and monitored the cell cycle in individual live cells over time by determining the ratios between red fluorescence (RF) of RFP-Cdt1 and green fluorescence (GF) of GFP-Geminin. Cytotoxic and cytostatic compounds, the latter of which induced G2 or mitotic arrest, were identified based on periodic cycling of the RF/GF and GF/RF ratios in FUCCI-HeLa cells treated with anti-cancer drugs. With this cell cycle monitoring system, ten flavonoids were screened. Of these, apigenin and luteolin, which have a flavone backbone, were cytotoxic, whereas kaempferol, which has a flavonol backbone, was cytostatic and induced G2 arrest. In summary, we developed a system to quantitatively monitor the cell cycle in real time. This system can be used to identify novel compounds that modulate the cell cycle and to investigate structure-activity relationships.

Selective Elimination of Culture-Adapted Human Embryonic Stem Cells with BH3 Mimetics

The selective survival advantage of culture-adapted human embryonic stem cells (hESCs) is a serious safety concern for their clinical application. With a set of hESCs with various passage numbers, we observed that a subpopulation of hESCs at late passage numbers was highly resistant to various cell death stimuli, such as YM155, a survivin inhibitor. Transcriptome analysis from YM155-sensitive (YM155S) and YM155-resistant (YM155R) hESCs demonstrated that BCL2L1 was highly expressed in YM155R hESCs. By matching the gene signature of YM155R hESCs with the Cancer Therapeutics Response Portal dataset, BH3 mimetics were predicted to selectively ablate these cells. Indeed, short-course treatment with a sub-optimal dose of BH3 mimetics induced the spontaneous death of YM155R, but not YM155S hESCs by disrupting the mitochondrial membrane potential. YM155S hESCs remained pluripotent following BH3 mimetics treatment. Therefore, the use of BH3 mimetics is a promising strategy to specifically eliminate hESCs with a selective survival advantage.

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Culture-adapted hESCs against YM155/genotoxic agents mediated by high BCL-xL expression

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Selective cell death of culture-adapted hPSCs by BH3 mimetics

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Pluripotency maintenance of normal hESCs after exposure to BH3 mimetics

Optimizing tissue-clearing conditions based on analysis of the critical factors affecting tissue-clearing procedures

Tissue-clearing techniques have received great attention for volume imaging and for the potential to be applied in optical diagnosis. In principle, tissue clearing is achieved by reducing light scattering through a combination of lipid removal, size change, and matching of the refractive index (RI) between the imaging solution and the tissue. However, the contributions of these major factors in tissue clearing have not been systematically evaluated yet. In this study, we experimentally measured and mathematically calculated the contribution of these factors to the clearing of four organs (brain, liver, kidney, and lung). We found that these factors differentially influence the maximal clearing efficacy of tissues and the diffusivity of materials inside the tissue. We propose that these physical properties of organs can be utilized for the quality control (Q/C) process during tissue clearing, as well as for the monitoring of the pathological changes of tissues.

A fluorescent chemical probe CDy9 selectively stains and enables the isolation of live naïve mouse embryonic stem cells

Human and mouse embryonic stem cells (ESCs) differ in terms of their pluripotency status, i.e., naïve vs. primed. This affects various biological properties and leads to several technical hurdles for future clinical applications, such as difficulties in chimera formation, single-cell passaging, and gene editing. In terms of generating functional human tissues and organs via mammalian interspecies chimerism, a fluorescent chemical probe that specifically labels naïve ESCs would help to isolate these cells and monitor their conversion. This study demonstrates that the fluorescent chemical probe compound of designation yellow 9 (CDy9) selectively stains naïve, but not primed, mouse ESCs (mESCs). CDy9 entered cells via Slc13a5, a highly expressed membrane transporter in naïve mESCs. Fluorescence-based cell sorting based on CDy9 staining successfully separated naïve mESCs from primed mESCs. Mice generated using CDy9⁺ cells isolated during the conversion of mouse epiblast stem cells into naïve mESCs exhibited coat color chimerism. Furthermore, CDy9 specifically stained cells in the inner cell mass of mouse embryos. These findings suggest that CDy9 is a useful tool to isolate functional naïve mESCs.

Suppression of SIRT2 and altered acetylation status of human pluripotent stem cells: possible link to metabolic switch during reprogramming

Primed human pluripotent stem cells (hPSCs) are highly dependent on glycolysis rather than oxidative phosphorylation, which is similar to the metabolic switch that occurs in cancer cells. However, the molecular mechanisms that underlie this metabolic reprogramming in hPSCs and its relevance to pluripotency remain unclear. Cha et al. (2017) recently revealed that downregulation of SIRT2 by miR-200c enhances acetylation of glycolytic enzymes and glycolysis, which in turn facilitates cellular reprogramming, suggesting that SIRT2 is a key enzyme linking the metabolic switch and pluripotency in hPSCs.

Proactive strategy for long-term biological research aimed at low-dose radiation risk in Korea

PURPOSE

Since the 2011 Fukushima nuclear power plant accident, Korean radiation experts have agreed that reliable data on health risks of low-dose radiation (LDR) are needed to ease the anxiety of lay people. The intent of this study was to devise a sustainable biological program suited for the research environment in Korea and aimed at the health effects of radiation exposures <100 millisieverts (mSv). To address pressing public concerns over LDR risk, we investigated the current understanding of LDR effects by analyzing the previous reports of international authorities for radiation protection and research publications that appeared after the Chernobyl accident. A research program appropriate for societal and scientific inclinations of Korea was then devised based on input from Korean radiation scientists.

CONCLUSIONS

After review by our advisory committee, program priorities were set, calling for an agenda that focused on dose-response relationships in carcinogenesis, health span responses to lifestyle variations, and systemic metabolic changes. Our long-term biological research program may contribute scientific evidence to reduce the uncertainties of LDR health risks and help stakeholders formulate policies for radiation protection.

Designing Tyrosinase siRNAs by Multiple Prediction Algorithms and Evaluation of Their Anti-Melanogenic Effects

Melanin is a pigment produced from tyrosine in melanocytes. Although melanin has a protective role against UVB radiation-induced damage, it is also associated with the development of melanoma and darker skin tone. Tyrosinase is a key enzyme in melanin synthesis, which regulates the rate-limiting step during conversion of tyrosine into DOPA and dopaquinone. To develop effective RNA interference therapeutics, we designed a melanin siRNA pool by applying multiple prediction programs to reduce human tyrosinase levels. First, 272 siRNAs passed the target accessibility evaluation using the RNAxs program. Then we selected 34 siRNA sequences with ΔG ≥-34.6 kcal/mol, i-Score value ≥65, and siRNA scales score ≤30. siRNAs were designed as 19-bp RNA duplexes with an asymmetric 3' overhang at the 3' end of the antisense strand. We tested if these siRNAs effectively reduced tyrosinase gene expression using qRT-PCR and found that 17 siRNA sequences were more effective than commercially available siRNA. Three siRNAs further tested showed an effective visual color change in MNT-1 human cells without cytotoxic effects, indicating these sequences are anti-melanogenic. Our study revealed that human tyrosinase siRNAs could be efficiently designed using multiple prediction algorithms.

Inhibition of BET selectively eliminates undifferentiated pluripotent stem cells

Embryonic stem cells (ESCs) maintain their cellular identity through the systematic regulation of master transcription factors and chromatin remodeling complexes. Recent work has shown that the unusually large-scale enhancers-namely super-enhancers (SEs), on which BRD4, a member of the bromodomain and extraterminal domain (BET) family is highly enriched-could regulate pluripotency-related transcription factors. Moreover, inhibition of BRD4 binding on SEs has been shown to induce the differentiation of ESCs. However, the underlying mechanism of BRD4 inhibition-mediated stem cell differentiation remains elusive. Here we show that both mouse and human ESCs lose their capacity for self-renewal upon treatment with JQ1, a selective inhibitor of BET family including BRD4, with rapid suppression of pluripotency-associated genes. Notably, a high concentration of JQ1 could selectively eliminate ESCs via apoptosis, without affecting the functionality of differentiated somatic cells from ESCs, suggesting that inhibition of BET may have a beneficial effect on the development of pluripotent stem cell-based cell therapy.

Enhancement of wound healing efficiency mediated by artificial dermis functionalized with EGF or NRG1

The use of artificial dermis as a skin substitute is a field of active study, as acellular dermal matrices from cadavers are susceptible to infection owing to their human origin. One such alternative dermal replacement scaffold, INSUREGRAF^®, is derived primarily from extracellular matrix proteins such as collagen and elastin and has been clinically used to treat severe skin wounds such as burns. This scaffold has proven to be useful to minimize wound contraction and scar formation owing to its biocompatibility, interconnected pore structure, sufficient biodegradability, and suitable mechanical properties. However, INSUREGRAF^® does not provide scar-free wound healing in cases of severe skin damage such as full-thickness (FT) excision. Considering that the efficient recruitment of fibroblasts and keratinocytes into a wound site represents a critical step in the regeneration of damaged skin, we attempted to enhance the efficiency for wound healing by fabricating growth factor-functionalized INSUREGRAF^®. In particular, we utilized epidermal growth factor (EGF) and an EGF family member, neuregulin-1 (NRG1), not previously studied in the context of wound healing, whose cellular role is to promote proliferation and migration in fibroblasts and keratinocytes. Both artificial dermis-growth factor combinations led to efficient recruitment of fibroblasts and keratinocytes into a wound site during the early steps of skin regeneration. Notably, EGF- or NRG1-functionalized INSUREGRAF^® induced rapid proliferation of skin cells in an ERK pathway-dependent manner and exhibited efficient wound healing in a Sprague-Dawley rat FT excision and grafting model. These results provide the foundation for expanding the use of growth factor-functionalized INSUREGRAF^® to clinical application in cases of severe skin injury.

Effect of the sexual abstinence period recommended by the World Health Organization on clinical outcomes of fresh embryo transfer cycles with normal ovarian response after intracytoplasmic sperm injection

This study was to investigate whether the sexual abstinence period (SAP) recommended by the World Health Organization (WHO) affects clinical outcomes. We compared the rate of clinical outcomes between 2-7 and ≥8 days of SAP in first fresh embryo transfer after intracytoplasmic sperm injection (ICSI) in groups of young maternal age (YMA: <38 years) and old maternal age (OMA: ≥38 years). We conducted a retrospective study of 449 first ICSI cycles with a normal ovarian response. SAP was identified before collecting the semen samples. Semen analysis was performed based on the guidelines recommended by WHO (2010). Sperm preparation was made using the swim-up method. Patients' baseline characteristics in the YMA and OMA groups did not differ. The rates of fertilisation, top-quality embryos on day 3, biochemical pregnancy, clinical pregnancy, ongoing pregnancy, abortion and implantation per cycle were not significantly different between 2-7 and ≥8 days of SAP in the YMA or OMA group. In conclusion, SAP beyond the recommended period by WHO was not associated with the rates of a lower fertilisation and pregnancy in human in vitro fertilisation (IVF). We think that a new criterion of SAP for clinical application in human IVF needs to be considered by WHO.

Chronic TGFβ stimulation promotes the metastatic potential of lung cancer cells by Snail protein stabilization through integrin β3-Akt-GSK3β signaling

Chronic exposure to TGFβ, a frequent occurrence for tumor cells in the tumor microenvironment, confers more aggressive phenotypes on cancer cells by promoting their invasion and migration while at the same time increasing their resistance to the growth-inhibitory effect of TGFβ. In this study, a transdifferentiated (TD) A549 cell model, established by chronically exposing A549 cells to TGFβ, showed highly invasive phenotypes in conjunction with attenuation of Smad-dependent signaling. We show that Snail protein, the mRNA expression of which strongly correlates with a poor prognosis in lung cancer patients, was highly stable in TD cells after TGFβ stimulation. The increased protein stability of Snail in TD cells correlated with elevated inhibitory phosphorylation of GSK3β, resulting from the high Akt activity. Notably, integrin β3, whose expression was markedly increased upon sustained exposure to TGFβ, was responsible for the high Akt activity as well as the increased Snail protein stability in TD cells. Consistently, clinical database analysis on lung cancer patients revealed a negative correlation between overall survival and integrin β3 mRNA levels. Therefore, we suggest that the integrin β3-Akt-GSK3β signaling axis plays an important role in non-canonical TGFβ signaling, determining the invasive properties of tumor cells chronically exposed to TGFβ.

Tumor necrosis factor-inducible gene 6 protein ameliorates chronic liver damage by promoting autophagy formation in mice

Tumor necrosis factor-inducible gene 6 protein (TSG-6) has recently been shown to protect the liver from acute damage. However, the mechanism underlying the effect of TSG-6 on the liver remains unclear. Autophagy is a catabolic process that targets cell components to lysosomes for degradation, and its functions are reported to be dysregulated in liver diseases. Here we investigate whether TSG-6 promotes liver regeneration by inducing autophagic clearance in damaged livers. Mice fed a methionine choline-deficient diet supplemented with 0.1% ethionine (MCDE) for 2 weeks were injected with TSG-6 (the M+TSG-6 group) or saline (the M+V group) and fed with MCDE for 2 additional weeks. Histomorphological evidence of injury and increased levels of liver enzymes were evident in MCDE-treated mice, whereas these symptoms were ameliorated in the M+TSG-6 group. Livers from this group contained less active caspase-3 and more Ki67-positive hepatocytic cells than the M+V group. The autophagy markers ATG3, ATG7, LC3-II, LAMP2A and RAB7 were elevated in the M+TSG-6 group compared with those in the M+V group. Immunostaining for LC3 and RAB7 and electron microscopy analysis showed the accumulation of autophagy structures in the M+TSG-6 group. TSG-6 also blocked both tunicamycin- and palmitate-induced apoptosis of hepatocytes and increased their viability by inducing autophagy formation in these cells. An autophagy inhibitor suppressed TSG-6-mediated autophagy in the injured hepatocytes and livers of MCDE-treated mice. These results therefore demonstrate that TSG-6 protects hepatocytes from damage by enhancing autophagy influx and contributes to liver regeneration, suggesting that TSG-6 has therapeutic potential for the treatment of liver diseases.

Role of MEK partner-1 in cancer stemness through MEK/ERK pathway in cancerous neural stem cells, expressing EGFRviii

Background

Glioma stem cells (GSCs) are a major cause of the frequent relapse observed in glioma, due to their high drug resistance and their differentiation potential. Therefore, understanding the molecular mechanisms governing the ‘cancer stemness’ of GSCs will be particularly important for improving the prognosis of glioma patients.

Methods

We previously established cancerous neural stem cells (CNSCs) from immortalized human neural stem cells (F3 cells), using the H-Ras oncogene. In this study, we utilized the EGFRviii mutation, which frequently occurs in brain cancers, to establish another CNSC line (F3.EGFRviii), and characterized its stemness under spheroid culture.

Results

The F3.EGFRviii cell line was highly tumorigenic in vitro and showed high ERK1/2 activity as well as expression of a variety of genes associated with cancer stemness, such as SOX2 and NANOG, under spheroid culture conditions. Through meta-analysis, PCR super-array, and subsequent biochemical assays, the induction of MEK partner-1 (MP1, encoded by the LAMTOR3 gene) was shown to play an important role in maintaining ERK1/2 activity during the acquisition of cancer stemness under spheroid culture conditions. High expression of this gene was also closely associated with poor prognosis in brain cancer.

Conclusion

These data suggest that MP1 contributes to cancer stemness in EGFRviii-expressing glioma cells by driving ERK activity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0703-y) contains supplementary material, which is available to authorized users.

Helping Induced hPSCs Clean Up Their Act

Inhibition of the tumorigenic potential of human pluripotent stem cells (hPSCs) remains critically important for safe hPSC-based therapy. In this issue of Cell Chemical Biology, Kuang et al. (2017) reveal that the phospho-D-peptide D-3 efficiently induces death of residual hPSCs, but not of differentiated progenies, through high alkaline phosphatase activity in hPSCs.

Abstract 4761: BCL2 induced by LAMTOR3-MAPK is a druggable target of chemoradioresistance in mesenchymal lung cancer

Metastasis and chemoresistance, which are main causes of lung cancer related death, have been major interest in cancer research. Recently, Epithelial-Mesenchymal Transition (EMT) a foremost process for acquiring metastatic properties has been demonstrated to be strongly link to chemoresistance. Due to limited understanding of mechanism for EMT mediated chemoresistance, druggable targets for chemoresistance remained unidentified yet. In this study, we established the mesenchymal like cancer cells (MLCCs) from A549 lung cancer cells with chronic exposure of TGFβ. With clinicogenomics database analysis and following validation with MLCC model, we determined that BCL2, of which expression was clearly induced and indicated a poor prognosis in the mesenchymal cancer patients, was responsible for high chemoresistance in MLCCs. Therefore combined treatment of chemotherapeutic drug and BH3 mimetic such as ABT-263 or ABT-737, remarkably sensitized MLCCs to chemo and radio therapy. Furthermore, BCL2 expression was governed by sustained ERK1 activity in MLCCs, which resulted from high level of MEK partner-1 (MP1) protein expression. Therefore, combined chemotherapy with small molecules (approved by FDA or clinically tested) targeting for MEK1 or BCL2 would be a clinically feasible approach to overcome EMT related chemoresistance.

Citation Format: Ok-Seon Kwon, Soon-Ki Hong, Hyuk-Jin Cha. BCL2 induced by LAMTOR3-MAPK is a druggable target of chemoradioresistance in mesenchymal lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4761. doi:10.1158/1538-7445.AM2017-4761