Histone methyltransferase KMT5C drives liver cancer progression and directs therapeutic response to PARP inhibitors.

BACKGROUND AND AIMS: Epigenetic plasticity is a major challenge in cancer-targeted therapy. However, the molecular basis governing this process has not yet been clearly defined. Despite the considerable success of poly(ADP-ribose) polymerase inhibitors (PARPi) in cancer therapy, the limited response to PARPi, especially in HCC, has been a bottleneck in its clinical implications. Herein, we investigated the molecular basis of the histone methyltransferase KMT5C (lysine methyltransferase 5C) that governs PARPi sensitivity and explored a potential therapeutic strategy for enhancing PARPi efficacy. APPROACH AND RESULTS: We identified KMT5C, a trimethyltransferase of H4K20, as a targetable epigenetic factor that promoted liver tumor growth in mouse de novo MYC/Trp53-/- and xenograft liver tumor models. Notably, induction of KMT5C by environmental stress was crucial for DNA repair and HCC cell survival. Mechanistically, KMT5C interacted with the pivotal component of homologous recombination repair, RAD51, and promoted RAD51/RAD54 complex formation, which was essential for the activation of dsDNA breaks repair. This effect depended on the methyltransferase activity of KMT5C. We further demonstrated that the function of KMT5C in promoting HCC progression was dependent on RAD51. Importantly, either a pharmacological inhibitor (A196) or genetic inhibition of KMT5C sensitized liver cancer cells to PARPi. CONCLUSIONS: KMT5C played a vital role in promoting liver cancer progression by activating the DNA repair response. Our results revealed a novel therapeutic approach using the KMT5C inhibitor A196, concurrent with olaparib, as a potential HCC therapy.

hnRNPA2B1 promotes the occurrence and progression of hepatocellular carcinoma by downregulating PCK1 mRNA via a m6A RNA methylation manner.

BACKGROUND: N6-methyladenosine (m6A) is the most prevalent RNA modification. Although hnRNPA2B1, as a reader of m6A modification, has been reported to promote tumorigenesis in a few types of tumors, its role in hepatocellular carcinoma (HCC) and the underlying molecular mechanism remains unclear. METHODS: Multiple public databases were used to analyze the expression of hnRNPA2B1 in HCC and its correlation with survival prognosis. We employed a CRISPR-Cas9 sgRNA editing strategy to knockout hnRNPA2B1 expression in HCC cells. The biological function of hnRNPA2B1 in vitro in HCC cells was measured by CCK8, colony formation, migration, and invasion assay. The tumorigenic function of hnRNPA2B1 in vivo was determined by a subcutaneous tumor formation experiment and a HCC mouse model via tail injection of several plasmids into the mouse within 5s-7s. RNA binding protein immunoprecipitation (RIP) experiment using hnRNPA2B1 was performed to test the target genes of hnRNPA2B1 and methylated RNA immunoprecipitation (MeRIP) assay was performed to explore the m6A methylated mRNA of target genes. RESULTS: hnRNPA2B1 highly expressed in HCC tissues, correlated with high grades and poor prognosis. Its knockout reduced HCC cell proliferation, migration, and invasion in vitro, while overexpression promoted these processes. hnRNPA2B1-knockout cells inhibited tumor formation in graft experiments. In HCC mice, endogenous knockout attenuated hepatocarcinogenesis. RNA-seq showed downregulated gluconeogenesis with high hnRNPA2B1 expression. hnRNPA2B1 negatively correlated with PCK1, a key enzyme. RIP assay revealed hnRNPA2B1 binding to PCK1 mRNA. hnRNPA2B1 knockout increased m6A-methylation of PCK1 mRNA. Interestingly, PCK1 knockout partially counteracted tumor inhibition by hnRNPA2B1 knockout in mice. CONCLUSION: Our study indicated that hnRNPA2B1 is highly expressed in HCC and correlated with a poor prognosis. hnRNPA2B1 promotes the tumorigenesis and progression of HCC both in vitro and in vivo. Moreover, hnRNPA2B1 downregulates the expression of PCK1 mRNA via a m6A methylation manner. More importantly, the ability of hnRNPA2B1 to induce tumorigenesis and progression in HCC is dependent on its ability to decrease the expression of PCK1. Therefore, this study suggested that hnRNPA2B1 might be a diagnostic marker of poor prognosis of HCC and a potential therapeutic target for HCC patients.

Single-cell spatial transcriptomic analysis reveals common and divergent features of developing postnatal granule cerebellar cells and medulloblastoma.

BACKGROUND: Cerebellar neurogenesis involves the generation of large numbers of cerebellar granule neurons (GNs) throughout development of the cerebellum, a process that involves tight regulation of proliferation and differentiation of granule neuron progenitors (GNPs). A number of transcriptional regulators, including Math1, and the signaling molecules Wnt and Shh have been shown to have important roles in GNP proliferation and differentiation, and deregulation of granule cell development has been reported to be associated with the pathogenesis of medulloblastoma. While the progenitor/differentiation states of cerebellar granule cells have been broadly investigated, a more detailed association between developmental differentiation programs and spatial gene expression patterns, and how these lead to differential generation of distinct types of medulloblastoma remains poorly understood. Here, we provide a comparative single-cell spatial transcriptomics analysis to better understand the similarities and differences between developing granule and medulloblastoma cells. RESULTS: To acquire an enhanced understanding of the precise cellular states of developing cerebellar granule cells, we performed single-cell RNA sequencing of 24,919 murine cerebellar cells from granule neuron-specific reporter mice (Math1-GFP; Dcx-DsRed mice). Our single-cell analysis revealed that there are four major states of developing cerebellar granule cells, including two subsets of granule progenitors and two subsets of differentiating/differentiated granule neurons. Further spatial transcriptomics technology enabled visualization of their spatial locations in cerebellum. In addition, we performed single-cell RNA sequencing of 18,372 cells from Patched+/- mutant mice and found that the transformed granule cells in medulloblastoma closely resembled developing granule neurons of varying differentiation states. However, transformed granule neuron progenitors in medulloblastoma exhibit noticeably less tendency to differentiate compared with cells in normal development. CONCLUSION: In sum, our study revealed the cellular and spatial organization of the detailed states of cerebellar granule cells and provided direct evidence for the similarities and discrepancies between normal cerebellar development and tumorigenesis.

Single-cell RNA sequencing reveals the epithelial cell heterogeneity and invasive subpopulation in human bladder cancer.

Bladder cancer represents a highly heterogeneous disease characterized by distinct histological, molecular and clinical phenotypes, and a detailed analysis of tumor cell invasion and crosstalks within bladder tumor cells has not been determined. Here, we applied droplet-based single-cell RNA sequencing (scRNA-seq) to acquire transcriptional profiles of 36 619 single cells isolated from seven patients. Single cell transcriptional profiles matched well with the pathological basal/luminal subtypes. Notably, in T1 tumors diagnosed as luminal subtype, basal cells displayed characteristics of epithelial-mesenchymal transition (EMT) and mainly located at the tumor-stromal interface as well as micrometastases in the lamina propria. In one T3 tumor, muscle-invasive tumor showed significantly higher expression of cancer stem cell markers SOX9 and SOX2 than the primary tumor. We additionally analyzed communications between tumor cells and demonstrated its relevance to basal/luminal phenotypes. Overall, our single-cell study provides a deeper insight into the tumor cell heterogeneity associated with bladder cancer progression.

Targeted Delivery of CXCL9 and OX40L by Mesenchymal Stem Cells Elicits Potent Antitumor Immunity.

Major obstacles in immunotherapies include toxicities associated with systemic administration of therapeutic agents, as well as low tumor lymphocyte infiltration that hampers the efficacies. In this study, we report a mesenchymal stem cell (MSC)-based immunotherapeutic strategy in which MSCs specifically deliver T/natural killer (NK) cell-targeting chemokine CXCL9 and immunostimulatory factor OX40 ligand (OX40L)/tumor necrosis factor superfamily member 4 (TNFSF4) to tumor sites in syngeneic subcutaneous and azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced spontaneous colon cancer mouse models. This approach generated potent local antitumor immunity by increasing the ratios of tumor-infiltrating CD8+ T and NK cells and production of antitumor cytokines and cytolytic proteins in the tumor microenvironment. Moreover, it improved the efficacy of programmed death-1 (PD-1) blockade in a syngeneic mouse model and significantly suppressed the growth of major histocompatibility complex class I (MHC class I)-deficient tumors. Our MSC-based immunotherapeutic strategy simultaneously recruits and activates immune effector cells at the tumor site, thus overcoming the problems with toxicities of systemic therapeutic agents and low lymphocyte infiltration of solid tumors.

E-cadherin bridges cell polarity and spindle orientation to ensure prostate epithelial integrity and prevent carcinogenesis in vivo.

Cell polarity and correct mitotic spindle positioning are essential for the maintenance of a proper prostate epithelial architecture, and disruption of the two biological features occurs at early stages in prostate tumorigenesis. However, whether and how these two epithelial attributes are connected in vivo is largely unknown. We herein report that conditional genetic deletion of E-cadherin, a key component of adherens junctions, in a mouse model results in loss of prostate luminal cell polarity and randomization of spindle orientations. Critically, E-cadherin ablation causes prostatic hyperplasia which progresses to invasive adenocarcinoma. Mechanistically, E-cadherin and the spindle positioning determinant LGN interacts with the PDZ domain of cell polarity protein SCRIB and form a ternary protein complex to bridge cell polarity and cell division orientation. These findings provide a novel mechanism by which E-cadherin acts an anchor to maintain prostate epithelial integrity and to prevent carcinogenesis in vivo.

Loss of Setd2 promotes Kras-induced acinar-to-ductal metaplasia and epithelia-mesenchymal transition during pancreatic carcinogenesis.

OBJECTIVE: SETD2, the sole histone H3K36 trimethyltransferase, is frequently mutated or deleted in human cancer, including pancreatic ductal adenocarcinoma (PDAC). However, whether SETD2/H3K36me3 alteration results in PDAC remains largely unknown. DESIGN: TCGA(PAAD) public database and PDAC tissue array with SETD2/H3K36me3 staining were used to investigate the clinical relevance of SETD2 in PDAC. Furthermore, to define the role of SETD2 in the carcinogenesis of PDAC, we crossed conditional Setd2 knockout mice (PdxcreSetd2flox/flox) together with KrasG12D mice. Moreover, to examine the role of SETD2 after ductal metaplasia, Crisp/cas9 was used to deplete Setd2 in PDAC cells. RNA-seq and H3K36me3 ChIP-seq were performed to uncover the mechanism. RESULTS: SETD2 mutant/low expression was correlated with poor prognosis in patients with PDAC. Next, we found that Setd2 acted as a putative tumour suppressor in Kras-driven pancreatic carcinogenesis. Mechanistically, Setd2 loss in acinar cells facilitated Kras-induced acinar-to-ductal reprogramming, mainly through epigenetic dysregulation of Fbxw7. Moreover, Setd2 ablation in pancreatic cancer cells enhanced epithelia-mesenchymal transition (EMT) through impaired epigenetic regulation of Ctnna1. In addition, Setd2 deficiency led to sustained Akt activation via inherent extracellular matrix (ECM) production, which would favour their metastasis. CONCLUSION: Together, our findings highlight the function of SETD2 during pancreatic carcinogenesis, which would advance our understanding of epigenetic dysregulation in PDAC. Moreover, it may also pave the way for development of targeted, patients-tailored therapies for PDAC patients with SETD2 deficiency.

CD16 expression on neutrophils predicts treatment efficacy of capecitabine in colorectal cancer patients.

BACKGROUND: Early detection of capecitabine-resistance could largely increase overall survival of colorectal cancer (CRC) patients. Previous studies suggested examination of immune cells in peripheral blood would help to predict efficacy of chemotherapy. METHODS: We examined the immunological characteristics of peripheral blood in CRC patients with capecitabine treatment. We analyzed the relationships between the abnormal immune cell population in capecitabine-resistance patients and major clinical features. Furthermore, RNA sequencing, analyses of cell surface marker expression and the correlations with other major immune cell populations were performed using this population to explore the possible function of these cells. RESULTS: The expression level of CD16 on neutrophils was down-regulated in capecitabine-resistant CRC patients. Patients with CD16low/-neutrophils after capecitabine therapy had adverse clinical features. What's important, the change of CD16 expression level on neutrophils appeared much earlier than CT scan. RNA sequencing revealed that CD16low/-neutrophils in capecitabine-resistant patients had lower expression level of neutrophil-related genes, compared to CD16+neutrophils in capecitabine-sensitive patients, suggesting this CD16low/-population might be immature neutrophils. Furthermore, the expression level of CD16 on neutrophils in patients with capecitabine treatment was positively correlated with the number of anti-tumor immune cell subsets, such as CD8+T cell, CD4+T cell, NK cell and monocyte. CONCLUSIONS: Our findings indicated that CD16 expression on neutrophils in peripheral blood was a good prognostic marker for predicting efficacy of capecitabine in CRC patients.

Decreased immunomodulatory and secretory capability of aging human umbilical cord mesenchymal stem cells in vitro.

Mesenchymal stem cell therapy has drawn much attention as a promising therapeutic option for the treatment of different diseases. Due to insufficient cell population derived from freshly isolated tissues, in vitro propagation is required prior to clinical use. However, reduced cell viability of aging mesenchymal stem cell (MSCs) with repeated propagations has yet not be fully investigated, especially for the biological characteristics of immunoregulatory ability and paracrine factors. In this study, we compared the biological properties of human umbilical cord-MSCs (hUC-MSCs) at different passages, especially for immunomodulatory ability and secretions. Our results showed that hUC-MSCs at early passage (P2) and late passage (P8) exhibited similar morphology and surface marker expression, but hUC-MSCs at P8 displayed reduced proliferation and differentiation potential, immunoregulatory and secretory ability. In particular, hUC-MSCs at P2 and P5 could significantly suppress the population of proinflammatory Th1 and Th17 cell subsets and upregulate Treg cells, but not with hUC-MSCs at P8. For paracrine mechanism, higher level of secretions such as growth factors, cell adhesions, anti-inflammatory factors of hUC-MSCs were observed at P2 and P5 compared to that at P8. Therefore, it is essential to verify and validate the biological characteristics of hUC-MSCs that possess a good vitality before they are released for clinical use. Altogether, this study provides a rationale and two important parameters for how to select appropriate passage and vitality of MSCs for cell therapy.

Wnt/ß-catenin signaling contributes to prostate cancer heterogeneity through reciprocal suppression of H3K27 trimethylation.

Intratumoral heterogeneity remains as a major challenge in the treatment resistance of prostate cancer. Understanding the mechanism of prostate cancer heterogeneity is essential for developing effective therapies. In this study, we reported the heterogeneous activation of Wnt/ß-catenin signaling in prostate cancer. We developed a Wnt/ß-catenin signaling reporting system to directly characterize the differences between Wnt/ß-catenin signaling active (GFP+) and inactive (GFP-) cells. Compared to GFP- cells, GFP+ cells demonstrated cancer stem cell properties with higher colony formation efficiency, slower cell cycle, higher resistance to docetaxel and higher expression of cancer stem cell markers. In addition, we found that Wnt/ß-catenin signaling is negatively correlated with H3K27me3 levels. Further studies demonstrated that Wnt/ß-catenin signaling affected H3K27me3 levels by regulating the expression of KDM6A, one of the H3K27me3 demethylases. H3K27me3 suppressed Wnt/ß-catenin signaling by directly silencing LEF1 promoter. Together, our studies suggest that Wnt/ß-catenin signaling makes a major contribution to prostate cancer heterogeneity and targeting both Wnt/ß-catenin signaling active and inactive populations is essential for developing more effective therapies.

Carbon Monoxide Impairs CD11b+Ly-6Chi Monocyte Migration from the Blood to Inflamed Pancreas via Inhibition of the CCL2/CCR2 Axis.

Acute pancreatitis (AP) is a sterile inflammation, in which inflammatory monocytes (CD11b+Ly-6Chi) are recruited into the inflamed tissue at the onset of disease. Monocyte infiltration and activation at the site of inflammation are critical to the pathogenesis of AP. Our previous studies have shown a protective role for CO in AP, which is partially mediated by inhibition of macrophage activation via TLR4 signaling. In the current study, to gain a better understanding of CO's therapeutic effect, we further investigated whether CO could affect inflammatory monocyte trafficking during AP. In a mouse model of AP, we found that treatment with CO-releasing molecule-2 (CORM-2) impaired recruitment of inflammatory monocytes, but not that of neutrophils, from peripheral blood to inflamed pancreas. During the early stage of AP, a single dose of CORM-2 decreased pancreatic CCL2 and soluble ICAM-1 expression. In addition, using in vivo and in vitro experiments, we found that CORM-2 had the ability to inhibit CD11b+Ly-6Chi monocyte migration via blockade of CCR2 endocytosis. Notably, we showed that CORM-2 inhibited CCR2 endocytosis of inflammatory monocytes (CD14hiCD16-) from AP patients. Taken together, our results highlighted CO's effect on inflammatory monocyte trafficking, shedding additional light on its therapeutic potential in AP.

A MicroRNA302-367-Erk1/2-Klf2-S1pr1 Pathway Prevents Tumor Growth via Restricting Angiogenesis and Improving Vascular Stability.

RATIONALE: Angiogenic hypersprouting and leaky vessels are essential for tumor growth. MicroRNAs have unique therapeutic advantages by targeting multiple pathways of tumor-associated angiogenesis, but the function of individual miRNAs of miR302-367 cluster in angiogenesis and tumors has not yet been fully evaluated. OBJECTIVE: To investigate the functions of miR302-367 in developmental angiogenesis and tumor angiogenesis and explore the molecular mechanisms of microRNA for the treatment of pathological neovascularization-related diseases. METHODS AND RESULTS: Here, we show that miR302-367 elevation in endothelial cells reduces retinal sprouting angiogenesis and promotes vascular stability in vivo, ex vivo, and in vitro. Erk1/2 is identified as direct target of miR302-367, and downregulation of Erk1/2 on miR302-367 elevation in endothelial cells increases the expression of Klf2 and in turn S1pr1 and its downstream target VE-cadherin, suppressing angiogenesis and improving vascular stability. Conversely, both pharmacological blockade and genetic deletion of S1pr1 in endothelial cells reverse the antiangiogenic and vascular stabilizing effect of miR302-367 in mice. Tumor angiogenesis shares features of developmental angiogenesis, and endothelial specific elevation of miR302-367 reduces tumor growth by restricting sprout angiogenesis and decreasing vascular permeability via the same Erk1/2-Klf2-S1pr1 pathways. CONCLUSIONS: MiR302-367 regulation of an Erk1/2-Klf2-S1pr1 pathway in the endothelium advances our understanding of angiogenesis, meanwhile also provides opportunities for therapeutic intervention of tumor growth.

IRTKS is correlated with progression and survival time of patients with gastric cancer.

BACKGROUND AND OBJECTIVES: IRTKS functions as a novel regulator of tumour suppressor p53; however, the role of IRTKS in pathogenesis of gastric cancer is unclear. DESIGN: We used immunohistochemistry to detect IRTKS levels in 527 human gastric cancer specimens. We generated both IRTKS-deficient and p53-deficient mice to observe survival time of these mice and to isolate mouse embryonic fibroblasts (MEFs) for evaluating in vivo tumorigenicity. Co-immunoprecipitation was used to study the interaction among p53, MDM2 and IRTKS, as well as the ubiquitination of p53. RESULTS: IRTKS was significantly overexpressed in human gastric cancer, which was conversely associated with wild-type p53 expression. Among patients with wild-type p53 (n=206), those with high IRTKS expression (n=141) had a shorter survival time than those with low IRTKS (n=65) (p=0.0153). Heterozygous p53+/- mice with IRTKS deficiency exhibited significantly delayed tumorigenesis and an extended tumour-free survival time. p53+/- MEFs without IRTKS exhibited attenuated in vivo tumorigenicity. IRTKS depletion upregulated p53 and its target genes, such as BAX and p21. Intriguingly, IRTKS overexpression promoted p53 ubiquitination and degradation in MEFs and gastric cancer cells. Under DNA damage conditions, IRTKS was phosphorylated at Ser331 by the activated Chk2 kinase and then dissociated from p53, along with the p53-specific E3 ubiquitin ligase MDM2, resulting in attenuated p53 ubiquitination and degradation. CONCLUSION: IRTKS overexpression is negatively correlated with progression and overall survival time of patients with gastric cancer with wild-type p53 through promotion of p53 degradation via the ubiquitin/proteasome pathway.

Pharmacological inhibition of the Notch pathway enhances the efficacy of androgen deprivation therapy for prostate cancer.

Although androgen deprivation therapy (ADT) is a standard treatment for metastatic prostate cancer, this disease inevitably recurs and progresses to ADT-resistant stage after this therapy. Accordingly, understanding the mechanism of resistance to ADT and finding new approach to enhance the efficacy of ADT may provide a major benefit to PCa patients. In our study, we found upregulated expression of Notch receptors is positive associated with ADT-resistance progression. Using fluorescent Notch signaling reporter system, we observed that endogenous Notch signaling could be activated after treatment of androgen deprivation in LNCaP cells via activation of Notch3. In addition, exogenous activation of the Notch signaling though Dox-induced overexpression of any Notch intracellular domains (NICD1-4) could enhance the resistance of PCa cells to ADT under ex vivo 3D culture conditions and upregulate expression of ADT resistance-associated phospho-p38 and Bcl-2 in LNCaP cells. As a result, pharmacological inhibition of the Notch pathway using γ-secretase inhibitor (GSI), DAPT, downregulated both phospho-p38 and Bcl-2 expression and significantly enhanced the efficacy of ADT in androgen sensitive PCa cells with impaired proliferation and 3D colony formation, increased apoptosis and remarkable inhibition of tumor growth in murine subcutaneous xenograft model. These results indicate that activated Notch signaling contributes to ADT resistance, and suggest that inhibition of the Notch pathway may be a promising adjuvant therapy of ADT for PCa.

Shp2 and Pten have antagonistic roles in myeloproliferation but cooperate to promote erythropoiesis in mammals.

Previous data suggested a negative role of phosphatase and tensin homolog (Pten) and a positive function of SH2-containing tyrosine phosphatase (Shp2)/Ptpn11 in myelopoiesis and leukemogenesis. Herein we demonstrate that ablating Shp2 indeed suppressed the myeloproliferative effect of Pten loss, indicating directly opposing functions between pathways regulated by these two enzymes. Surprisingly, the Shp2 and Pten double-knockout mice suffered lethal anemia, a phenotype that reveals previously unappreciated cooperative roles of Pten and Shp2 in erythropoiesis. The lethal anemia was caused collectively by skewed progenitor differentiation and shortened erythrocyte lifespan. Consistently, treatment of Pten-deficient mice with a specific Shp2 inhibitor suppressed myeloproliferative neoplasm while causing anemia. These results identify concerted actions of Pten and Shp2 in promoting erythropoiesis, while acting antagonistically in myeloproliferative neoplasm development. This study illustrates cell type-specific signal cross-talk in blood cell lineages, and will guide better design of pharmaceuticals for leukemia and other types of cancer in the era of precision medicine.

Concise Review: Patient-Derived Stem Cell Research for Monogenic Disorders.

Monogenic disorders (MGDs) are caused by a single gene mutation and have a serious impact on human health. At present, there are no effective therapeutic methods for MGDs. Stem cell techniques provide insights into potential treatments for MGDs. With the development of patient-derived stem cells, we can begin to progressively understand the molecular mechanism of MGDs and identify new drugs for MGD treatment. Using powerful genome editing tools, such as zinc finger nucleases, transcriptional activator-like effector nucleases, and the clustered regulatory interspaced short palindromic repeat/Cas9 system, MGD-associated gene mutations can be corrected in MGD stem cells in vitro and then transplanted into MGD animal models to assess their safety and therapeutic effects. Despite the continued challenges surrounding potential pluripotent stem cell tumorigenicity and concerns regarding the genetic modification of stem cells, the extensive clinical application of MGD patient-specific stem cells will be pursued through further advances in basic research in the MGD field. In this review, we will summarize the latest progress in research into the use of patient-derived stem cells for the potential treatment of MGDs and provide predictions regarding the direction of future investigations.

A candidate gastric stem/progenitor cell marker revealed by genome-wide analysis.

Despite the important role of the gastric stem cell in tissue homeostasis and gastric carcinogenesis, its residence and identity remain poorly understood. In a recent paper in The Journal of Pathology, Vange et al suggest ASPM as a candidate stem/progenitor cell marker for oxyntic glands. Identification of ASPM was achieved by genome-wide gene expression analysis of the micro-dissected isthmus zone, where the majority of stem/progenitor cells are believed to reside. ASPM-positive cells, scattered in the proliferative isthmus region, do not express most differentiated cell markers and are largely quiescent. Together with ASPM, 11 other genes that are uniquely expressed in the isthmus zone constitute a regulatory network downstream of the core transcription factor E2F1. The authors further demonstrated that up-regulation of E2F1 and ASPM is associated with gastric cancers. This study provides novel candidates for future lineage-tracing experiments that will lead to the ultimate discovery of bona fide gastric stem cell markers. Additionally, the E2F1-ASPM axis may represent a new mechanism for gastric carcinogenesis.

Chemical conversion of mouse fibroblasts into functional dopaminergic neurons.

Ectopic expression of lineage-specific transcription factors facilitates the conversion of mammalian somatic cells into dopaminergic (DA) neurons, which is a promising strategy for cell therapy of Parkinson's disease (PD). However, this approach still has some drawbacks limiting its clinical application due to the potential risks of integrating vectors into the host genome. Therefore, it is critical to seek a more desired approach to generate DA neurons derived from mammalian somatic cells. Here, we report that mouse embryonic fibroblasts (MEFs) can be efficiently converted into DA neurons by using small molecules along with specific growth factors. These neuron-like cells generate DA neuronal morphology, and acquire immunocytochemical and calcium imaging special for neuronal electrophysiological profile. More importantly, these converted cells can secrete dopamine, indicating that they are functionally similar to DA neurons. Taken together, our study might provide a promising cell source for treating PD by using chemical approach without introduction of exogenous transcription factors.

COP1 is a tumour suppressor that causes degradation of ETS transcription factors.

The proto-oncogenes ETV1, ETV4 and ETV5 encode transcription factors in the E26 transformation-specific (ETS) family, which includes the most frequently rearranged and overexpressed genes in prostate cancer. Despite being critical regulators of development, little is known about their post-translational regulation. Here we identify the ubiquitin ligase COP1 (also known as RFWD2) as a tumour suppressor that negatively regulates ETV1, ETV4 and ETV5. ETV1, which is mutated in prostate cancer more often, was degraded after being ubiquitinated by COP1. Truncated ETV1 encoded by prostate cancer translocation TMPRSS2:ETV1 lacks the critical COP1 binding motifs and was 50-fold more stable than wild-type ETV1. Almost all patient translocations render ETV1 insensitive to COP1, implying that this confers a selective advantage to prostate epithelial cells. Indeed, COP1 deficiency in mouse prostate elevated ETV1 and produced increased cell proliferation, hyperplasia, and early prostate intraepithelial neoplasia. Combined loss of COP1 and PTEN enhanced the invasiveness of mouse prostate adenocarcinomas. Finally, rare human prostate cancer samples showed hemizygous loss of the COP1 gene, loss of COP1 protein, and elevated ETV1 protein while lacking a translocation event. These findings identify COP1 as a tumour suppressor whose downregulation promotes prostatic epithelial cell proliferation and tumorigenesis.

Proteomic Comparison and MRM-Based Comparative Analysis of Metabolites Reveal Metabolic Shift in Human Prostate Cancer Cell Lines.

One of the major challenges in prostate cancer therapy remains the development of effective treatments for castration-resistant prostate cancer (CRPC), as the underlying mechanisms for its progression remain elusive. Previous studies showed that androgen receptor (AR) is crucially involved in regulation of metabolism in prostate cancer (PCa) cells throughout the transition from early stage, androgen-sensitive PCa to androgen-independent CRPC. AR achieves such metabolic rewiring directively either via its transcriptional activity or via interactions with AMP-activated protein kinase (AMPK). However, due to the heterogeneous expression and activity status of AR in PCa cells, it remains a challenge to investigate the links between AR status and metabolic alterations. To this end, we compared the proteomes of three pairs of androgen-sensitive (AS) and androgen-independent (AI) PCa cell lines, namely, PC3-AR(+)/PC3, 22Rv1/Du145, and LNCaP/C42B, using an iTRAQ labeling approach. Our results revealed that most of the differentially expressed proteins between each pair function in metabolism, indicating a metabolic shift between AS and AI cells, as further validated by multiple reaction monitoring (MRM)-based quantification of nucleotides and relative comparison of fatty acids between these cell lines. Furthermore, increased adenylate kinase isoenzyme 1 (AK1) in AS relative to AI cells may result in activation of AMPK, representing a major regulatory factor involved in the observed metabolic shift in PCa cells.