The Retinoblastoma Tumor Suppressor Protein (pRb)/E2 Promoter Binding Factor 1 (E2F1) Pathway as a Novel Mediator of TGFβ-induced Autophagy

The role of imprinting genes' loss of imprints in cancers and their clinical implications

Genomic imprinting plays an important role in the growth and development of mammals. When the original imprint status of these genes is lost, known as loss of imprinting (LOI), it may affect growth, neurocognitive development, metabolism, and even tumor susceptibility. The LOI of imprint genes has gradually been found not only as an early event in tumorigenesis, but also to be involved in progression. More than 120 imprinted genes had been identified in humans. In this review, we summarized the most studied LOI of two gene clusters and 13 single genes in cancers. We focused on the roles they played, that is, as growth suppressors and anti-apoptosis agents, sustaining proliferative signaling or inducing angiogenesis; the molecular pathways they regulated; and especially their clinical significance. It is notable that 12 combined forms of multi-genes' LOI, 3 of which have already been used as diagnostic models, achieved good sensitivity, specificity, and accuracy. In addition, the methods used for LOI detection in existing research are classified into detection of biallelic expression (BAE), differentially methylated regions (DMRs), methylation, and single-nucleotide polymorphisms (SNPs). These all indicated that the detection of imprinting genes' LOI has potential clinical significance in cancer diagnosis, treatment, and prognosis.

The Intricate Interplay between Cell Cycle Regulators and Autophagy in Cancer

Simple Summary

Autophagy is an intracellular catabolic program regulated by multiple external and internal cues. A large amount of evidence unraveled that cell-cycle regulators are crucial in its control. This review highlights the interplay between cell-cycle regulators, including cyclin-dependent kinase inhibitors, cyclin-dependent kinases, and E2F factors, in the control of autophagy all along the cell cycle. Beyond the intimate link between cell cycle and autophagy, this review opens therapeutic perspectives in modulating together these two aspects to block cancer progression.

Abstract

In the past decade, cell cycle regulators have extended their canonical role in cell cycle progression to the regulation of various cellular processes, including cellular metabolism. The regulation of metabolism is intimately connected with the function of autophagy, a catabolic process that promotes the efficient recycling of endogenous components from both extrinsic stress, e.g., nutrient deprivation, and intrinsic sub-lethal damage. Mediating cellular homeostasis and cytoprotection, autophagy is found to be dysregulated in numerous pathophysiological contexts, such as cancer. As an adaptative advantage, the upregulation of autophagy allows tumor cells to integrate stress signals, escaping multiple cell death mechanisms. Nevertheless, the precise role of autophagy during tumor development and progression remains highly context-dependent. Recently, multiple articles has suggested the importance of various cell cycle regulators in the modulation of autophagic processes. Here, we review the current clues indicating that cell-cycle regulators, including cyclin-dependent kinase inhibitors (CKIs), cyclin-dependent kinases (CDKs), and E2F transcription factors, are intrinsically linked to the regulation of autophagy. As an increasing number of studies highlight the importance of autophagy in cancer progression, we finally evoke new perspectives in therapeutic avenues that may include both cell cycle inhibitors and autophagy modulators to synergize antitumor efficacy.

Transcription Factor E2F1 Knockout Promotes Mice White Adipose Tissue Browning Through Autophagy Inhibition

Obesity is associated with energy metabolic disturbance and is caused by long-term excessive energy storage in white adipose tissue (WAT). The WAT browning potentially reduces excessive energy accumulation, contributing an attractive target to combat obesity. As a pivotal regulator of cell growth, the transcription factor E2F1 activity dysregulation leads to metabolic complications. The regulatory effect and underlying mechanism of E2F1 knockout on WAT browning, have not been fully elucidated. To address this issue, in this study, the in vivo adipose morphology, mitochondria quantities, uncoupling protein 1 (UCP-1), autophagy-related genes in WAT of wild-type (WT) and E2F1^–/– mice were detected. Furthermore, we evaluated the UCP-1, and autophagy-related gene expression in WT and E2F1^–/– adipocyte in vitro. The results demonstrated that E2F1 knockout could increase mitochondria and UCP-1 expression in WAT through autophagy suppression in mice, thus promoting WAT browning. Besides, adipocytes lacking E2F1 showed upregulated UCP-1 and downregulated autophagy-related genes expression in vitro. These results verified that E2F1 knockout exerted effects on inducing mice WAT browning through autophagy inhibition in vivo and in vitro. These findings regarding the molecular mechanism of E2F1-modulated autophagy in controlling WAT plasticity, provide a novel insight into the functional network with the potential therapeutic application against obesity.

Comparison of the therapeutic effects of lobaplatin and carboplatin on retinoblastoma in vitro and in vivo

Retinoblastoma (RB) is one of the most aggressive malignancies affecting infants and children. Platinum drugs are commonly used in the treatment of RB; however, their efficacy is often compromised by drug resistance and severe toxicity. The present study aimed to investigate and compare the toxicity and antitumor activity of the third-generation platinum drugs, carboplatin and lobaplatin, in vitro and in vivo. The Y79 RB cell line was treated with carboplatin or lobaplatin in vitro and then used to establish xenografts in immunodeficient nude mice in vivo; the effects of pharmacological doses of these drugs were then assessed. High concentrations of carboplatin and lobaplatin markedly inhibited Y79 RB cell proliferation in vitro. In addition, the lobaplatin group exhibited higher proportions of early-stage apoptotic cells than the carboplatin group, while no significant differences in the proportions of cells in the S phase were observed between the 2 groups, as shown by flow cytometry. Significant changes in the E2F1/Cdc25a/Cdk2 pathway in the RB cells were detected by RNA-seq following carboplatin or lobaplatin intervention. RT-qPCR, immunofluorescence and immunohistochemical analyses in vivo and in vitro demonstrated that the trends of drug-induced inhibition of tumor pathological changes may have been regulated through the E2F1/Cdc25a/Cdk2 pathway, and that lobaplatin was more effective than carboplatin in controlling tumors in vivo. On the whole, the findings of the present study demonstrate that lobaplatin is associated with lower cytotoxicity and exerts more prominent therapeutic effects than carboplatin on Y79 RB cells in vitro and in mice in vivo.

An integrative multi-omics approach uncovers the regulatory role of CDK7 and CDK4 in autophagy activation induced by silica nanoparticles

Dysfunction of macroautophagy/autophagy has been postulated as a major cellular toxicological response to nanomaterials. It has been reported that excessive autophagy activation, induced by silica nanoparticles (SiNPs), contributes to autophagy dysfunction, whereas little is known how SiNPs trigger autophagy activation. Here, we treated normal rat kidney (NRK) cells using 3 different sizes of SiNPs (16, 29, and 51 nm) and observed that 16-nm SiNPs, with a final concentration of 60 μg/mL, dramatically induce autophagy activation without reducing cell viability. We further conducted a transcriptomic, proteomic, and phosphoproteomic profiling, and detected 23 autophagy-related (Atg) genes and 35 autophagy regulators regulated on at least one omic layer. To identify key regulators from the multi-omics data, we developed a new algorithm of computational prediction of master autophagy-regulating kinases (cMAK) to detect 21 candidates and revealed the CDK7-CDK4 cascade to be functional. The silence or inhibition of Cdk7 or Cdk4 significantly attenuated autophagic activation but not influenced autophagic flux blockage induced by 16-nm SiNPs. Further computational modeling indicated that the CDK7-CDK4 signaling axis potentially triggers autophagy activation by phosphorylating RB1 (RB transcriptional corepressor 1), activating two critical transcription factors, E2F1 (E2F transcription factor 1) and FOXO3 (forkhead box O3), and enhancing the transcriptional levels of at least 8 Atg genes and autophagy regulators in response to SiNPs. Our studies not only established a powerful method for predicting regulatory kinases from the multi-omics data but also revealed a potential mechanism of SiNP-triggered autophagy activation through modulating the CDK7-CDK4 cascade.Abbreviations: 3-MA: 3-methyladenine; Atg: autophagy-related; BECN1: beclin 1; CCK-8: cell counting kit-8; CDK4: cyclin dependent kinase 4; CDK7: cyclin dependent kinase 7; cMAK: computational prediction of master autophagy-regulating kinases; CQ: chloroquine; DMEM: Dulbecco's modified Eagle's medium; DMSO: dimethyl sulfoxide; E-ratio: enrichment ratio; E2F1: E2F transcription factor 1; EBSS: Earle's balanced salt solution; ER: endoplasmic reticulum; FOXO3: forkhead box O3; FPKM: fragments per kilobase of exon per million fragments mapped; GO: gene ontology; H₂O₂: hydrogen peroxide; iGPS: in vivo GPS; KEGG: Kyoto Encyclopedia of Genes and Genomes; LC-MS/MS: liquid chromatography-tandem mass spectrometry; LDH: lactate dehydrogenase; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3 beta; NRK: normal rat kidney; p-site: phosphorylation site; PBS: phosphate-buffered saline; PDI: polydispersity index; PTM: post-translational modification; QKS: quantitative kinase state; RB1: RB transcriptional corepressor 1; RBHs: reciprocal best hits; RNA-Seq: RNA sequencing; ROS: reactive oxygen species; rSiNPs: SiNPs fluorescently labeled with rhodamine B; SEM: scanning electronic microscopy; SiNPs: silica nanoparticles; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; ssKSR: site-specific kinase-substrate relation; TEM: transmission electron microscopy; tfLC3: mRFP-GFP tandem fluorescent-tagged LC3.

Transcription Factor E2F1 Aggravates Neurological Injury in Ischemic Stroke via microRNA-122-Targeted Sprouty2

BACKGROUND

It has been documented that microRNAs (miRs) assume a pivotal role in the development of ischemic stroke (IS). However, it remains poorly identified about the role of miR-122 in IS. Herein, this study was intended to explore the mechanism of E2F1-orchestrated miR-122 in IS.

PATIENTS AND METHODS

E2F1, miR-122, and SPRY2 expression in serum from patients with IS and oxygen-glucose deprivation (OGD)-treated N2a cells was detected by RT-qPCR. After gain- and loss-of-function approaches in OGD-induced N2a cells, GAFP staining, flow cytometry, and Western blot analysis were adopted to assess neuronal viability, cell cycle and apoptosis, and expression of apoptosis- and autophagy-related proteins, respectively. Meanwhile, mice with IS were induced, in which E2F1, miR-122, and SPRY2 were overexpressed, followed by evaluation of neurological deficit and cerebral infarction area. The MAPK pathway activity in tissues of mice and cells was determined.

RESULTS

miR-122 was down-regulated, and E2F1 and SPRY2 were up-regulated in IS patients and OGD-induced N2a cells. E2F1 inhibited miR-122 transcription, while miR-122 targeted SPRY2. Overexpression (OE) of miR-122 or down-regulation of E2F1 or SPRY2 increased viability, but decreased apoptosis, cell cycle arrest, and autophagy in OGD-induced N2a cells. In IS mice, the neurological deficit score and cerebral infarction area were elevated, which was aggravated by up-regulating E2F1 or SPRY2 but attenuated by overexpressing miR-122. E2F1/miR-122/SPRY2 axis mediated the MAPK pathway in vivo and in vitro.

CONCLUSION

Collectively, E2F1 reduced miR-122 transcription to up-regulate SPRY2, which inactivated MAPK pathway and promoted neurological deficit in IS.

A Novel E2F1-EP300-VMP1 Pathway Mediates Gemcitabine-Induced Autophagy in Pancreatic Cancer Cells Carrying Oncogenic KRAS

Autophagy is an evolutionarily preserved degradation process of cytoplasmic cellular constituents, which participates in cell response to disease. We previously characterized VMP1 (Vacuole Membrane Protein 1) as an essential autophagy related protein that mediates autophagy in pancreatic diseases. We also demonstrated that VMP1-mediated autophagy is induced by HIF-1A (hypoxia inducible factor 1 subunit alpha) in colon-cancer tumor cell lines, conferring resistance to photodynamic treatment. Here we identify a new molecular pathway, mediated by VMP1, by which gemcitabine is able to trigger autophagy in human pancreatic tumor cell lines. We demonstrated that gemcitabine requires the VMP1 expression to induce autophagy in the highly resistant pancreatic cancer cells PANC-1 and MIAPaCa-2 that carry activated KRAS. E2F1 is a transcription factor that is regulated by the retinoblastoma pathway. We found that E2F1 is an effector of gemcitabine-induced autophagy and regulates the expression and promoter activity of VMP1. Chromatin immunoprecipitation assays demonstrated that E2F1 binds to the VMP1 promoter in PANC-1 cells. We have also identified the histone acetyltransferase EP300 as a modulator of VMP1 promoter activity. Our data showed that the E2F1-EP300 activator/co-activator complex is part of the regulatory pathway controlling the expression and promoter activity of VMP1 triggered by gemcitabine in PANC-1 cells. Finally, we found that neither VMP1 nor E2F1 are induced by gemcitabine treatment in BxPC-3 cells, which do not carry oncogenic KRAS and are sensitive to chemotherapy. In conclusion, we have identified the E2F1-EP300-VMP1 pathway that mediates gemcitabine-induced autophagy in pancreatic cancer cells. These results strongly support that VMP1-mediated autophagy may integrate the complex network of events involved in pancreatic ductal adenocarcinoma chemo-resistance. Our experimental findings point at E2F1 and VMP1 as novel potential therapeutic targets in precise treatment strategies for pancreatic cancer.

Transforming growth factor β1 suppresses proinflammatory gene program independent of its regulation on vascular smooth muscle differentiation and autophagy

Transforming growth factor β (TGFβ) signaling plays crucial roles in maintaining vascular integrity and homeostasis, and is established as a strong activator of vascular smooth muscle cell (VSMC) differentiation. Chronic inflammation is a hallmark of various vascular diseases. Although TGFβ signaling has been suggested to be protective against inflammatory aortic aneurysm progression, its exact effects on VSMC inflammatory process and the underlying mechanisms are not fully unraveled. Here we revealed that TGFβ1 suppressed the expression of a broad array of proinflammatory genes while potently induced the expression of contractile genes in cultured primary human coronary artery SMCs (HCASMCs). The regulation of TGFβ1 on VSMC contractile and proinflammatory gene programs appeared to occur in parallel and both processes were through a SMAD4-dependent canonical pathway. We also showed evidence that the suppression of TGFβ1 on VSMC proinflammatory genes was mediated, at least partially through the blockade of signal transducer and activator of transcription 3 (STAT3) and NF-κB pathways. Interestingly, our RNA-seq data also revealed that TGFβ1 suppressed gene expression of a battery of autophagy mediators, which was validated by western blot for the conversion of microtubule-associated protein light chain 3 (LC3) and by immunofluo-rescence staining for LC3 puncta. However, impairment of VSMC autophagy by ATG5 deletion failed to rescue TGFβ1 influence on both VSMC contractile and proinflammatory gene programs, suggesting that TGFβ1-regulated VSMC differentiation and inflammation are not attributed to TGFβ1 suppression on autophagy. In summary, our results demonstrated an important role of TGFβ signaling in suppressing proinflammatory gene program in cultured primary human VSMCs via the blockade on STAT3 and NF-κB pathway, therefore providing novel insights into the mechanisms underlying the protective role of TGFβ signaling in vascular diseases.

TGF-β3 Promotes MUC5AC Hyper-Expression by Modulating Autophagy Pathway in Airway Epithelium

Mucus secretion accumulation in the airways may act as a contributing factor for the development of airflow limitation in severe fetal asthma patients. Accumulated evidences showed that transforming growth factor beta (TGF-β) plays a regulatory role in airway remodeling including mucus hyper-secretion in asthma. However, the detailed molecular mechanisms of TGF-β3 induced MUC5AC hyper-expression in airway epithelium remains unclear. Here, we demonstrated the pivotal roles of autophagy in regulation of MUC5AC hyper-production induced by TGF-β3 in airway epithelium. Our experimental data showed that inhibiting autophagy pathway in repeated ovalbumin (OVA) exposed mice exhibited decreased airway hyper-response and airway inflammation, diminishing the expression of Muc5ac and TGF-β3. Furthermore, our studies demonstrated that autophagy was induced upon exposure to TGF-β3 and then mediated MUC5AC hyper-expression by activating the activator protein-1 (AP-1) in human bronchial epithelial cells. Finally, Smad2/3 pathway was involved in TGF-β3-induced MUC5AC hyper-expressions by promoting autophagy. These data indicated that autophagy was required for TGF-β3 induced airway mucous hyper-production, and that inhibition of autophagy exerted therapeutic benefits for TGF-β3 induced airway mucus secretion.

Overexpression of miR‑17‑5p protects against high glucose‑induced endothelial cell injury by targeting E2F1‑mediated suppression of autophagy and promotion of apoptosis

E2 promoter binding factor 1 (E2F1) has been reported to have an important regulatory role in cell survival during hyperglycemic conditions; however, the mechanisms remain to be fully elucidated. Bioinformatics analyses have suggested that microRNA (miR)‑17‑5p targets the 3'untranslated region (3'UTR) of E2F1. The aim of the present study was to characterize the protective effect of miR‑17‑5p/E2F1 on human umbilical vein endothelial cells (HUVECs) under high glucose (HG) conditions, to confirm the regulatory effect of miR‑17‑5p on E2F1/AMP‑activated protein kinase α2 (AMPKα2)‑mediated apoptosis and E2F1/mammalian target of rapamycin complex 1 (mTORC1)‑mediated autophagy. Bifluorescein experiments were performed to characterize the interaction between miR‑17‑5p and E2F1. The Cell Counting Kit‑8 assay, flow cytometry, immunofluorescence, and reverse transcription‑quantitative polymerase chain reaction and western blot analyses were used to detect cell viability, apoptosis, autophagy, and relative mRNA and protein expression, respectively. The results showed that HG induced the downregulation of miR‑17‑5p and upregulation of E2F1 during HUVEC injury. The downregulation of E2F1 inhibited HG‑induced HUVEC dysfunction by suppressing mTORC1‑mediated inhibition of autophagy and AMPKα2‑mediated promotion of apoptosis. The results suggested that inhibiting the expression of E2F1 protected against HG‑induced HUVEC injury via the activation of autophagy. The overexpression of miR‑17‑5p inhibited E2F1‑mediated HUVEC injury under HG conditions, which was reversed following transfection with an E2F1‑overexpression vector. The bifluorescein experiments showed that miR‑17‑5p targeted the 3'UTR of E2F1. Taken together, the results suggested that the expression of miR‑17‑5p inhibited HG‑induced endothelial cell injury by targeting E2F1.

The Complex Link between Apoptosis and Autophagy: a Promising New Role for RB

Physiological processes, as autophagy, proliferation and apoptosis are affected during carcinogenesis. Restoring cellular sensitivity to apoptotic stimuli, such as the antineoplastic cocktails, has been explored as a strategy to eliminate cancer cells. Autophagy, a physiological process of recycling organelles and macromolecules can be deviated from homeostasis to support cancer cells survival, proliferation, escape from apoptosis, and therapy resistance. The relationship between autophagy and apoptosis is complex and many stimuli can induce both processes. Most chemotherapeutic agents induce autophagy and it is not clear whether and how this chemotherapy-induced autophagy might contribute to resistance to apoptosis. Here, we review current strategies to sensitize cancer cells by interfering with autophagy. Moreover, we discuss a new link between autophagy and apoptosis: the tumor suppressor retinoblastoma protein (RB). Inactivation of RB is one of the earliest and more frequent hallmarks of cancer transformation, known to control cell cycle progression and apoptosis. Therefore, understanding RB functions in controlling cell fate is essential for an effective translation of RB status in cancer samples to the clinical outcome.

Defining the momiome: Promiscuous information transfer by mobile mitochondria and the mitochondrial genome

Mitochondria are complex intracellular organelles that have long been identified as the powerhouses of eukaryotic cells because of the central role they play in oxidative metabolism. A resurgence of interest in the study of mitochondria during the past decade has revealed that mitochondria also play key roles in cell signaling, proliferation, cell metabolism and cell death, and that genetic and/or metabolic alterations in mitochondria contribute to a number of diseases, including cancer. Mitochondria have been identified as signaling organelles, capable of mediating bidirectional intracellular information transfer: anterograde (from nucleus to mitochondria) and retrograde (from mitochondria to nucleus). More recently, evidence is now building that the role of mitochondria extends to intercellular communication as well, and that the mitochondrial genome (mtDNA) and even whole mitochondria are indeed mobile and can mediate information transfer between cells. We define this promiscuous information transfer function of mitochondria and mtDNA as "momiome" to include all mobile functions of mitochondria and the mitochondrial genome. Herein, we review the "momiome" and explore its role in cancer development, progression, and treatment.

Autophagy acts through TRAF3 and RELB to regulate gene expression via antagonism of SMAD proteins

Macroautophagy can regulate cell signalling and tumorigenesis via elusive molecular mechanisms. We establish a RAS mutant cancer cell model where the autophagy gene ATG5 is dispensable in A549 cells in vitro, yet promotes tumorigenesis in mice. ATG5 represses transcriptional activation by the TGFβ-SMAD gene regulatory pathway. However, autophagy does not terminate cytosolic signal transduction by TGFβ. Instead, we use proteomics to identify selective degradation of the signalling scaffold TRAF3. TRAF3 autophagy is driven by RAS and results in activation of the NF-κB family member RELB. We show that RELB represses TGFβ target promoters independently of DNA binding at NF-κB recognition sequences, instead binding with SMAD family member(s) at SMAD-response elements. Thus, autophagy antagonises TGFβ gene expression. Finally, autophagy-deficient A549 cells regain tumorigenicity upon SMAD4 knockdown. Thus, at least in this setting, a physiologic function for autophagic regulation of gene expression is tumour growth.

Macroautophagy can regulate cell signalling and tumorigenesis but the molecular mechanisms are unclear. Here the authors show selective degradation of the signalling scaffold TRAF3 by autophagy and consequent activation of the NF-κB family member RELB regulate gene expression via antagonism of SMAD proteins.

Transforming Growth Factor-beta Regulation of Ephrin Type-A Receptor 4 Signaling in Breast Cancer Cellular Migration

Breast cancer consists of a range of tumor subtypes with different clinical characteristics, disease prognosis, and treatment-response. Luminal breast cancer has the best prognosis while basal-like breast cancer (BLBC) represents the worst subtype. Transforming growth factor-beta (TGFβ) plays a prominent role in stimulating the migration and invasion of malignant breast cancer cells contributing to tumor progression. In this study, we identified the Ephrin type-A receptor 4 (EPHA4) as a novel target of TGFβ in breast cancer. Moreover, we show that TGFβ induction of EPHA4 gene expression is specific to basal-like tumors and is required for TGFβ-mediated cell migration. We further addressed the mechanism and found EPHA4 to be required for TGFβ-mediated cell migration in breast cancer through TGFβ-induced short term and long term activation of RhoGTPases. Finally, our data revealed a strong association between high EPHA4 expression and advanced tumor stage, aggressive BLBC molecular subtype and poor prognosis. Importantly, we found significant co-expression of EPHA4 and the TGFβ receptor type-2 (TGFβR2) in breast cancer subtypes associated with increased tumor relapse and drug resistance. Together, this study highlight the important role of the TGFβ/EPHA4 signaling axis in mediating tumor aggressiveness and poor patient survival in human breast cancer.

BANCR: a cancer-related long non-coding RNA

Long non-coding RNAs (lncRNAs) are a group of non-protein-coding RNAs with more than 200 nucleotides in length. lncRNAs are involved in diverse biological processes, including development, cell proliferation and differentiation. Emerging evidences also suggest that lncRNAs may participate in cancer development by functioning as tumor suppressors and oncogenes. BRAF-activated non-coding RNA (BANCR) was first identified as an oncogene in melanoma. Later studies demonstrated that BANCR was frequently deregulated in human cancers, including lung cancer, gastric cancer, colorectal cancer, thyroid cancer and osteosarcoma. Nevertheless, the direction of deregulation was tissue-specific in which BANCR could as an oncogene or tumor-suppressor gene. In this review, we compile current evidences concerning the functional roles and molecular mechanisms of BANCR in tumor development.

Immune modulation by a cellular network of mesenchymal stem cells and breast cancer cell subsets: Implication for cancer therapy

The immune modulatory properties of mesenchymal stem cells (MSCs) are mostly controlled by the particular microenvironment. Cancer stem cells (CSCs), which can initiate a clinical tumor, have been the subject of intense research. This review article discusses investigative studies of the roles of MSCs on cancer biology including on CSCs, and the potential as drug delivery to tumors. An understanding of how MSCs behave in the tumor microenvironment to facilitate the survival of tumor cells would be crucial to identify drug targets. More importantly, since CSCs survive for decades in dormancy for later resurgence, studies are presented to show how MSCs could be involved in maintaining dormancy. Although the mechanism by which CSCs survive is complex, this article focus on the cellular involvement of MSCs with regard to immune responses. We discuss the immunomodulatory mechanisms of MSC-CSC interaction in the context of therapeutic outcomes in oncology. We also discuss immunotherapy as a potential to circumventing this immune modulation.

Genomic structure, expression pattern, and functional characterization of transcription factor E2F-2 from black tiger shrimp (Penaeus monodon)

Transcription factor E2F-2 is a regulator of cell cycle. Researchers identified E2F-2 genes from yeasts to humans, but few reports investigated E2F-2 gene from black tiger shrimp. In the present study, we cloned E2F-2 gene from black tiger shrimp (Penaeus monodon). Full-length PmE2F-2 complementary DNA sequence measures 3,189 bp with an open reading frame of 1,371 bp. Complete PmE2F-2 genomic sequence (17,305 bp) of P. monodon contains nine exons, which are separated by eight introns. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that PmE2F-2 is highly expressed in hepatopancreas and ovaries of P. monodon. Highest PmE2F-2 expression levels were observed in stage III ovarian development of P. monodon. PmE2F-2 expression levels were significantly augmented in ovaries of P. monodon after 5-hydroxytryptamine injection and eyestalk ablation. RNA interference experiments were conducted to examine PmE2F-2, PmCDK2, and PmCyclin E expression profiles. PmE2F-2 was successfully knocked down in ovaries and hepatopancreas via double-stranded RNA (dsRNA)-E2F-2 injection. In the same organs, PmE2F-2 expression localization and level were investigated through in situ hybridization, which revealed consistent results with those of qRT-PCR. After dsRNA-E2F-2 injection, gonadosomatic index of shrimp was significantly lower than those following dsRNA-GFP and phosphate-buffered solution injections. Therefore, PmE2F-2 may be involved in ovarian maturation in P. monodon.

Autophagy and epithelial-mesenchymal transition: an intricate interplay in cancer

Autophagy and epithelial to mesenchymal transition (EMT) are major biological processes in cancer. Autophagy is a catabolic pathway that aids cancer cells to overcome intracellular or environmental stress, including nutrient deprivation, hypoxia and drugs effect. EMT is a complex transdifferentiation through which cancer cells acquire mesenchymal features, including motility and metastatic potential. Recent observations indicate that these two processes are linked in a complex relationship. On the one side, cells that underwent EMT require autophagy activation to survive during the metastatic spreading. On the other side, autophagy, acting as oncosuppressive signal, tends to inhibit the early phases of metastasization, contrasting the activation of the EMT mainly by selectively destabilizing crucial mediators of this process. Currently, still limited information is available regarding the molecular hubs at the interplay between autophagy and EMT. However, a growing number of evidence points to the functional interaction between cytoskeleton and mitochondria as one of the crucial regulatory center at the crossroad between these two biological processes. Cytoskeleton and mitochondria are linked in a tight functional relationship. Controlling mitochondria dynamics, the cytoskeleton cooperates to dictate mitochondria availability for the cell. Vice versa, the number and structure of mitochondria, which are primarily affected by autophagy-related processes, define the energy supply that cancer cells use to reorganize the cytoskeleton and to sustain cell movement during EMT. In this review, we aim to revise the evidence on the functional crosstalk between autophagy and EMT in cancer and to summarize the data supporting a parallel regulation of these two processes through shared signaling pathways. Furthermore, we intend to highlight the relevance of cytoskeleton and mitochondria in mediating the interaction between autophagy and EMT in cancer.

A dual prognostic role for the TGFβ receptors in human breast cancer

The transforming growth factor-β (TGFβ) plays a dual role in breast cancer, acting as a tumor suppressor in early carcinomas while promoting tumor metastasis in more advanced breast carcinoma. As a result, the prognostic role of TGFβ and its signaling components in breast cancer remains unclear. Here we evaluated the expression levels of TGFβ signaling receptors TβRII and TβRI using human breast cancer tissue microarrays and a large publicly available gene profiling database in relation to various clinicopathological parameters. Our results indicate that breast cancer tissues express lower TβRII and TβRI protein levels compared with normal breast tissue. In contrast to TβRI expression, TβRII mRNA expression levels were also significantly downregulated in invasive breast cancer compared with normal breast tissue (4.18-fold downregulation, P=9.3×10^-115). Interestingly, within the cancer cases analyzed, our results revealed a direct correlation between high TβRII and TβRI expression levels and classic poor prognostic clinicopathological parameters, including larger tumor size, advanced tumor stage, and poorly differentiated tumors. Next, we examined TGFβ receptors' expression in relation to breast cancer molecular subtypes. Importantly, our results revealed that whereas expression of TGFβ receptors in luminal A and triple-negative breast cancer showed no correlation with patient outcome, their expression in luminal B and HER2 subtypes showed significant association with favorable patient outcome. Together, these results indicate that although TGFβ receptors are downregulated in breast cancer, their expression in tumors is an indicator of aggressive breast cancer phenotype. Moreover, the relation between TGFβ pathway and patient outcome is breast cancer subtype dependent.