The role of AKT isoforms in glioblastoma: AKT3 delays tumor progression

PTEN decreases NR2F1 expression to inhibit ciliogenesis during EGFRL858R-induced lung cancer progression

Lung cancer is the major cause of death worldwide. Activation of oncogenes or inhibition of tumor suppressors causes cancer formation. Previous studies have indicated that PTEN, as a tumor suppressor, inhibits cancer formation. In this study, we studied the role of PTEN in EGFRL858R-induced lung cancer in vivo. Interestingly, loss of PTEN increased bronchial cell hyperplasia but decreased alveolar cell hyperplasia in EGFRL858R*PTEN-/--induced lung cancer. Systematic analysis of gene expression by RNA-seq showed that several genes related to ciliogenesis were upregulated in EGFRL858R*PTEN-/--induced lung cancer and subsequently showed that bronchial ciliated cells were hyperplastic. Several critical ciliogenesis-related genes, such as Mucin5A, DNAI2, and DNAI3, were found to be regulated by NR2F1. Next, NR2F1 was found to be inhibited by overexpression of PTEN, indicating that PTEN negatively regulates NR2F1, thereby inhibiting the expression of ciliogenesis-related genes and leading to the inhibition of bronchial cell hyperplasia during EGFRL858R-induced lung cancer progression. In addition, we also found that PTEN decreased AKT phosphorylation in A549, KRAS mutant, and H1299 cells but increased AKT phosphorylation in PC9, EGFRL858R, and H1299L858R cells, suggesting that PTEN may function as a tumor suppressor and an oncogene in lung cancers with KRAS mutation and EGFR mutation, respectively. PTEN acts as a double-edged sword that differentially regulates EGFRL858R-induced lung cancer progression in different genomic backgrounds. Understanding the PTEN in lung cancer with different genetic backgrounds will be beneficial for therapy in the future.

Non-coding RNAs (ncRNAs) and multidrug resistance in glioblastoma: Therapeutic challenges and opportunities

Non-coding RNAs (ncRNAs) have been recognized as pivotal regulators of transcriptional and post-transcriptional gene modulation, exerting a profound influence on a diverse array of biological and pathological cascades, including the intricate mechanisms underlying tumorigenesis and the acquisition of drug resistance in neoplastic cells. Glioblastoma (GBM), recognized as the foremost and most aggressive neoplasm originating in the brain, is distinguished by its formidable resistance to the cytotoxic effects of chemotherapeutic agents and ionizing radiation. Recent years have witnessed an escalating interest in comprehending the involvement of ncRNAs, particularly lncRNAs, in GBM chemoresistance. LncRNAs, a subclass of ncRNAs, have been demonstrated as dynamic modulators of gene expression at the epigenetic, transcriptional, and post-transcriptional levels. Disruption in the regulation of lncRNAs has been observed across various human malignancies, including GBM, and has been linked with developing multidrug resistance (MDR) against standard chemotherapeutic agents. The potential of targeting specific ncRNAs or their downstream effectors to surmount chemoresistance is also critically evaluated, specifically focusing on ongoing preclinical and clinical investigations exploring ncRNA-based therapeutic strategies for glioblastoma. Nonetheless, targeting lncRNAs for therapeutic objectives presents hurdles, including overcoming the blood-brain barrier and the brief lifespan of oligonucleotide RNA molecules. Understanding the complex relationship between ncRNAs and the chemoresistance characteristic in glioblastoma provides valuable insights into the fundamental molecular mechanisms. It opens the path for the progression of innovative and effective therapeutic approaches to counter the therapeutic challenges posed by this aggressive brain tumor. This comprehensive review highlights the complex functions of diverse ncRNAs, including miRNAs, circRNAs, and lncRNAs, in mediating glioblastoma's chemoresistance.

The Multifunctional Nature of the MicroRNA/AKT3 Regulatory Axis in Human Cancers

Serine/threonine kinase (AKT) signaling regulates diverse cellular processes and is one of the most important aberrant cell survival mechanisms associated with tumorigenesis, metastasis, and chemoresistance. Targeting AKT has become an effective therapeutic strategy for the treatment of many cancers. AKT3 (PKBγ), the least studied isoform of the AKT family, has emerged as a major contributor to malignancy. AKT3 is frequently overexpressed in human cancers, and many regulatory oncogenic or tumor suppressor small non-coding RNAs (ncRNAs), including microRNAs (miRNAs), have recently been identified to be involved in regulating AKT3 expression. Therefore, a better understanding of regulatory miRNA/AKT3 networks may reveal novel biomarkers for the diagnosis of patients with cancer and may provide invaluable information for developing more effective therapeutic strategies. The aim of this review was to summarize current research progress in the isoform-specific functions of AKT3 in human cancers and the roles of dysregulated miRNA/AKT3 in specific types of human cancers.

Isoforms of autophagy-related proteins: role in glioma progression and therapy resistance

Autophagy is the process of recycling and utilization of degraded organelles and macromolecules in the cell compartments formed during the fusion of autophagosomes with lysosomes. During autophagy induction the healthy and tumor cells adapt themselves to harsh conditions such as cellular stress or insufficient supply of nutrients in the cell environment to maintain their homeostasis. Autophagy is currently seen as a form of programmed cell death along with apoptosis and necroptosis. In recent years multiple studies have considered the autophagy as a potential mechanism of anticancer therapy in malignant glioma. Although, subsequent steps in autophagy development are known and well-described, on molecular level the mechanism of autophagosome initiation and maturation using autophagy-related proteins is under investigation. This article reviews current state about the mechanism of autophagy, its molecular pathways and the most recent studies on roles of autophagy-related proteins and their isoforms in glioma progression and its treatment.

Enhancing T Cell Chemotaxis and Infiltration in Glioblastoma

Glioblastoma is an immunologically 'cold' tumor, which are characterized by absent or minimal numbers of tumor-infiltrating lymphocytes (TILs). For those tumors that have been invaded by lymphocytes, they are profoundly exhausted and ineffective. While many immunotherapy approaches seek to reinvigorate immune cells at the tumor, this requires TILs to be present. Therefore, to unleash the full potential of immunotherapy in glioblastoma, the trafficking of lymphocytes to the tumor is highly desirable. However, the process of T cell recruitment into the central nervous system (CNS) is tightly regulated. Naïve T cells may undergo an initial licensing process to enter the migratory phenotype necessary to enter the CNS. T cells then must express appropriate integrins and selectin ligands to interact with transmembrane proteins at the blood-brain barrier (BBB). Finally, they must interact with antigen-presenting cells and undergo further licensing to enter the parenchyma. These T cells must then navigate the tumor microenvironment, which is rich in immunosuppressive factors. Altered tumoral metabolism also interferes with T cell motility. In this review, we will describe these processes and their mediators, along with potential therapeutic approaches to enhance trafficking. We also discuss safety considerations for such approaches as well as potential counteragents.

Promising potential of boron compounds against Glioblastoma: In Vitro antioxidant, anti-inflammatory and anticancer studies

Glioblastoma (GB) is the most common and aggressive primary malignant astrocytoma correlated with poor patient survival. There are no curative treatments for GB, and it becomes resistant to chemotherapy, radiation therapy, and immunotherapy. Resistance in GB cells is closely related to their states of redox imbalance, and the role of reactive oxygen species and its impact on cancer cell survival is still far from elucidation. Boron-containing compounds, especially boric acid (BA) and borax (BX) exhibited interesting biological effects involving antibacterial, antiviral, anti-cancerogenic, anti-mutagenic, anti-inflammatory as well as anti-oxidative features. Recent studies indicated that certain boron compounds could be cytotoxic on human GB. Nevertheless, there is gap of knowledge in the literature on exploring the underlying mechanisms of anti-GB action by boron compounds. Here, we identified and compared the potential anti-GB effect of both BA and BX, and revealed their underlying anti-GB mechanism. We performed cell viability, oxidative alterations, oxidative DNA damage potential assays, and explored the inflammatory responses and gene expression changes by real-time PCR using U-87MG cells. We found that BA and BX led to a remarkable reduction in U-87MG cell viability in a concentration-dependent manner. We also found that boron compounds increased the total oxidative status and MDA levels along with the SOD and CAT enzyme activities and decreased total antioxidant capacity and GSH levels in U-87MG cells without inducing DNA damage. The cytokine levels of cancer cells were also altered. We verified the selectivity of the compounds using a normal cell line, HaCaT and found an exact opposite condition after treating HaCaT cells with BA and BX. BA applications were more effective than BX on U-87MG cell line in terms of increasing MDA levels, SOD and CAT enzyme activities, and decreasing Interleukin-1α, Interleukin-6 and Tumor necrosis factor- α (TNF- α) levels. We finally observed that anticancer effect of BA and BX were associated with the BRAF/MAPK, PTEN and PI3K/AKT signaling pathways in respect of downregulatory manner. Especially, BA application was found more favorable because of its inhibitory effect on PIK3CA, PIK3R1, PTEN and RAF1 genes. In conclusion, our analysis indicated that boron compounds may be safe and promising for effective treatment of GB.

Integrative cBioPortal Analysis Revealed Molecular Mechanisms That Regulate EGFR-PI3K-AKT-mTOR Pathway in Diffuse Gliomas of the Brain

Simple Summary

The current classification of central nervous system tumors has incorporated molecular changes that have clarified biological behavior and categorized gliomas into different types and malignancy grades. The most malignant type—glioblastoma, represents one of the most therapeutically challenging tumors, with a median survival of only 12–14 months despite trimodal therapy. In our integrative large-scale study, we used genomics, transcriptomics, epigenomics, and proteomics to investigate and make sense of the molecular changes that activate or inhibit the EGFR-PI3K-AKT-mTOR signaling pathway. Different pathohistological types of diffuse brain gliomas harbored distinct changes. A better understanding of signaling pathway regulation helps to the discovery of new targets for glioma therapies. Our results have potential for diagnostics improvement and tailored therapies.

Abstract

Diffuse gliomas are a heterogeneous group of tumors with aggressive biological behavior and a lack of effective treatment methods. Despite new molecular findings, the differences between pathohistological types still require better understanding. In this in silico analysis, we investigated AKT1, AKT2, AKT3, CHUK, GSK3β, EGFR, PTEN, and PIK3AP1 as participants of EGFR-PI3K-AKT-mTOR signaling using data from the publicly available cBioPortal platform. Integrative large-scale analyses investigated changes in copy number aberrations (CNA), methylation, mRNA transcription and protein expression within 751 samples of diffuse astrocytomas, anaplastic astrocytomas and glioblastomas. The study showed a significant percentage of CNA in PTEN (76%), PIK3AP1 and CHUK (75% each), EGFR (74%), AKT2 (39%), AKT1 (32%), AKT3 (19%) and GSK3β (18%) in the total sample. Comprehensive statistical analyses show how genomics and epigenomics affect the expression of examined genes differently across various pathohistological types and grades, suggesting that genes AKT3, CHUK and PTEN behave like tumor suppressors, while AKT1, AKT2, EGFR, and PIK3AP1 show oncogenic behavior and are involved in enhanced activity of the EGFR-PI3K-AKT-mTOR signaling pathway. Our findings contribute to the knowledge of the molecular differences between pathohistological types and ultimately offer the possibility of new treatment targets and personalized therapies in patients with diffuse gliomas.

MicroRNA-424-5p inhibits the proliferation, migration, and invasion of nasopharyngeal carcinoma cells by decreasing AKT3 expression

This study examined the expression and potential mechanism of microRNA (miRNA)-424-5p in nasopharyngeal carcinoma (NPC). NPC tissues were collected from 40 patients who were enrolled in the study, and skin samples were collected from 26 healthy subjects during plastic surgery as controls. We performed various in vitro assays using miR-424-5p to examine its function in primary NPC-1 cells. Bioinformatics was employed to analyze potential target genes and signaling pathways of miR-424-5p. We found that miR-424-5p expression in NPC tissues is downregulated and negatively correlated with lymph node metastasis and clinical staging. Expression of miR-424-5p in NPC cells was also downregulated, and transfection with miR-424-5p mimics inhibited proliferation, migration, and invasion of NPC-1 cells. Bioinformatics identified the AKT3 gene as a potential target of miR-424-5p and dual luciferase assays confirmed this finding. Upregulation of AKT3 expression rescued the inhibitory effect of miR-424-5p on the proliferation, migration, and invasion. Our results suggest that miR-424-5p inhibited the proliferation, migration, and invasion of NPC cells by decreasing AKT3 expression.

Role of PI3K/AKT pathway in cancer: the framework of malignant behavior

Given that the PI3K/AKT pathway has manifested its compelling influence on multiple cellular process, we further review the roles of hyperactivation of PI3K/AKT pathway in various human cancers. We state the abnormalities of PI3K/AKT pathway in different cancers, which are closely related with tumorigenesis, proliferation, growth, apoptosis, invasion, metastasis, epithelial-mesenchymal transition, stem-like phenotype, immune microenvironment and drug resistance of cancer cells. In addition, we investigated the current clinical trials of inhibitors against PI3K/AKT pathway in cancers and found that the clinical efficacy of these inhibitors as monotherapy has so far been limited despite of the promising preclinical activity, which means combinations of targeted therapy may achieve better efficacies in cancers. In short, we hope to feature PI3K/AKT pathway in cancers to the clinic and bring the new promising to patients for targeted therapies.

AKT-Dependent Phosphorylation of ADAR1p110 and ADAR2 Represents a New and Important Link Between Cell Signaling and RNA Editing

RNA editing is a process by which nascent RNA transcripts are covalently modified, thus enhancing the complexity of the transcriptome. The most common modifications are deaminations of adenosine to inosine at sites of complex RNA secondary structure, a process that is carried out by the adenosine deaminase acting on double-strand RNA (ADAR) family of RNA editases. Although much has been learned about the ADAR family members since their discovery, very little information on their post-transcriptional regulation has been reported. Similar to most proteins, the ADAR family members are post-translationally modified at multiple sites. We recently reported that members of the AKT kinase family directly phosphorylate ADAR1p110 and ADAR2 on a conserved threonine within the catalytic domain of the protein. Phosphorylation was observed to differentially inhibit the enzymatic activity of the ADAR proteins toward known RNA substrates. The direct downstream involvement of the AKT kinases in multiple major signaling pathways associated with cell survival, growth, glucose metabolism (insulin signaling), and differentiation is well established; thus, the AKT kinases represent a link between ADAR-dependent A-to-I editing and major signal transduction pathways that are necessary for cell maintenance and development.

The Genetic Architecture of Gliomagenesis-Genetic Risk Variants Linked to Specific Molecular Subtypes

Genome-wide association studies have identified 25 germline genetic loci that increase the risk of glioma. The somatic tumor molecular alterations, including IDH-mutation status and 1p/19q co-deletion, have been included into the WHO 2016 classification system for glioma. To investigate how the germline genetic risk variants correlate with the somatic molecular subtypes put forward by WHO, we performed a meta-analysis that combined findings from 330 Swedish cases and 876 controls with two other recent studies. In total, 5,103 cases and 10,915 controls were included. Three categories of associations were found. First, variants in TERT and TP53 were associated with increased risk of all glioma subtypes. Second, variants in CDKN2B-AS1, EGFR, and RTEL1 were associated with IDH-wildtype glioma. Third, variants in CCDC26 (the 8q24 locus), C2orf80 (close to IDH), LRIG1, PHLDB1, ETFA, MAML2 and ZBTB16 were associated with IDH-mutant glioma. We therefore propose three etiopathological pathways in gliomagenesis based on germline variants for future guidance of diagnosis and potential functional targets for therapies. Future prospective clinical trials of patients with suspicion of glioma diagnoses, using the genetic variants as biomarkers, are necessary to disentangle how strongly they can predict glioma diagnosis.

Transcriptome profiling of cervical cancer cells acquired resistance to cisplatin by deep sequencing

Cervical cancer is one of the most fatal malignancies in females. Acquired resistance to chemotherapeutic agent is one reason behind this lethality. In this study, we developed cisplatin resistance cell line, subsequently examined the molecular mechanisms linked. Transcriptome sequencing technology was utilized to compare the various expression models between the cisplatin-resistant cell line (Hela/DDP) and its parental cell line human cervical adenocarcinoma Hela. The present study has identified 2,312 differentially expressed genes (DEGs). Results showed there were 1,437 up-regulated genes and 875 down-regulated ones. Databases analysis including Gene ontology (GO), Cluster of Orthologous Groups of proteins (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were performed to reveal potential molecular mechanisms. We studied AKT3, a crucial gene in the PI3K/AKT pathway which clustered the most DEGs. Silencing AKT3 in Hela/DDP could enhance its sensibility to cisplatin. Quantitative real-time reverse transcription PCR (qRT-PCR) and western blot experiments were showed that expression of AKT3 was decreased after siRNA interference and inhibitor treatment. CCK-8 experiments showed that low expression of Akt3/pAkt enhanced the sensitivity of drug-resistant cells to cisplatin. Apoptotic analysis demonstrated that inhibition of AKT3 increased the rate of Hela/DDP apoptosis. Our results suggest a novel mechanism by which upregulated expression of AKT3 in cervical cancer may lead to resistance to cisplatin.

Classification of glioma based on prognostic alternative splicing

BACKGROUND

Previously developed classifications of glioma have provided enormous advantages for the diagnosis and treatment of glioma. Although the role of alternative splicing (AS) in cancer, especially in glioma, has been validated, a comprehensive analysis of AS in glioma has not yet been conducted. In this study, we aimed at classifying glioma based on prognostic AS.

METHODS

Using the TCGA glioblastoma (GBM) and low-grade glioma (LGG) datasets, we analyzed prognostic splicing events. Consensus clustering analysis was conducted to classified glioma samples and correlation analysis was conducted to characterize regulatory network of splicing factors and splicing events.

RESULTS

We analyzed prognostic splicing events and proposed novel splicing classifications across pan-glioma samples (labeled pST1-7) and across GBM samples (labeled ST1-3). Distinct splicing profiles between GBM and LGG were observed, and the primary discriminator for the pan-glioma splicing classification was tumor grade. Subtype-specific splicing events were identified; one example is AS of zinc finger proteins, which is involved in glioma prognosis. Furthermore, correlation analysis of splicing factors and splicing events identified SNRPB and CELF2 as hub splicing factors that upregulated and downregulated oncogenic AS, respectively.

CONCLUSION

A comprehensive analysis of AS in glioma was conducted in this study, shedding new light on glioma heterogeneity and providing new insights into glioma diagnosis and treatment.

miR-145 sensitizes esophageal squamous cell carcinoma to cisplatin through directly inhibiting PI3K/AKT signaling pathway

Background

Esophageal squamous cell carcinoma (ESCC) is the eighth most common cancer worldwide and is one of the most lethal malignancies. Cisplatin (DDP) is a key drug for ESCC treatment, but the presence of chemotherapy resistance limits the use of DDP. To enhance chemosensitivity to DDP is important for ESCC treatment.

Methods

qRT-PCR and Western blotting detected mRNA and protein expression in ESCC tissues and cells. Luciferase reporter assay assessed the interaction between miR-145 and AKT3. Cell cycle, apoptosis and proliferation were investigated with flow cytometry and MTT assay, respectively. Nude mice xenograft model was established, and immunohistochemistry (IHC) and TUNEL assay were conducted to detect Ki-67 level and apoptosis in xenograft tumor.

Results

Down-regulated miR-145 and up-regulated AKT3 were observed in ESCC tissues and cells. Luciferase reporter assay revealed that miR-145 negatively regulated AKT3 through binding to its 3′-UTR. Overexpression of miR-145 or knockdown of AKT3 promoted DDP-induced cell cycle arrest and apoptosis, as well as reduced IC50 of DDP treatment, which was reversed by AKT3 overexpression. The expression level of MRP1, P-gp, CyclinD1, c-Myc and anti-apoptotic protein Bcl-2 were down-regulated, while pro-apoptotic protein Bax was up-regulated by miR-145. Furthermore, overexpression of miR-145 enhanced the DDP-induced tumor growth suppression in vivo.

Conclusion

miR-145 increased the sensitivity of ESCC to DDP, and facilitated DDP-induced apoptosis, cycle arrest by directly inhibiting PI3K/AKT signaling pathway to decrease multidrug resistance-associated proteins MRP1 and P-gp expression. Improving the efficacy of DDP by boosting the miR-145 level provides a new strategy for treatment of ESCC.

A novel tumor suppressor protein encoded by circular AKT3 RNA inhibits glioblastoma tumorigenicity by competing with active phosphoinositide-dependent Kinase-1

Background

The RTK/PI3K/AKT pathway plays key roles in the development and progression of many cancers, including GBM. As a regulatory molecule and a potential drug target, the oncogenic role of AKT has been substantially studied. Three isoforms of AKT have been identified, including AKT1, AKT2 and AKT3, but their individual functions in GBM remain controversial. Moreover, it is not known if there are more AKT alternative splicing variants.

Methods

High-throughput RNA sequencing and quantitative reverse transcription-PCR were used to identify the differentially expressed circRNAs in GBM samples and in paired normal tissues. High throughput RNA sequencing was used to identify circ-AKT3 regulated signaling pathways. Mass spectrometry, western blotting and immunofluorescence staining analyses were used to validate AKT3-174aa expression. The tumor suppressive role of AKT3-174aa was validated in vitro and in vivo. The competing interaction between AKT3-174aa and p-PDK1 was investigated by mass spectrometry and immunoprecipitation analyses.

Results

Circ-AKT3 is a previously uncharacterized AKT transcript variant. Circ-AKT3 is expressed at low levels in GBM tissues compared with the expression in paired adjacent normal brain tissues. Circ-AKT3 encodes a 174 amino acid (aa) novel protein, which we named AKT3-174aa, by utilizing overlapping start-stop codons. AKT3-174aa overexpression decreased the cell proliferation, radiation resistance and in vivo tumorigenicity of GBM cells, while the knockdown of circ-AKT3 enhanced the malignant phenotypes of astrocytoma cells. AKT3-174aa competitively interacts with phosphorylated PDK1, reduces AKT-thr308 phosphorylation, and plays a negative regulatory role in modulating the PI3K/AKT signal intensity.

Conclusions

Our data indicate that the impaired circRNA expression of the AKT3 gene contributes to GBM tumorigenesis, and our data corroborate the hypothesis that restoring AKT3-174aa while inhibiting activated AKT may provide more benefits for certain GBM patients.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1056-5) contains supplementary material, which is available to authorized users.

Isoform-Specific Role of Akt in Oral Squamous Cell Carcinoma

Protein kinase B (Akt) plays a very significant role in various cancers including oral cancer. However, it has three isoforms (Akt1, Akt2, and Akt3) and they perform distinct functions and even play contrasting roles in different cancers. Therefore, it becomes essential to evaluate the isoform-specific role of Akt in oral cancer. In the present study, an attempt has been made to elucidate the isoform-specific role of Akt in oral cancer. The immunohistochemical analysis of oral cancer tissues showed an overexpression of Akt1 and 2 isoforms but not Akt3. Moreover, the dataset of "The Cancer Genome Atlas" for head and neck cancer has suggested the genetic alterations of Akt1 and 2 tend to be associated with the utmost poor clinical outcome in oral cancer. Further, treatment of oral cancer cells with tobacco and its components such as benzo(a)pyrene and nicotine caused increased mRNA levels of Akt1 and 2 isoforms and also enhanced the aggressiveness of oral cancer cells in terms of proliferation, and clonogenic and migration potential. Finally, silencing of Akt1 and 2 isoforms caused decreased cell survival and induced cell cycle arrest at the G2/M phase. Akt1/2 silencing also reduced tobacco-induced aggressiveness by decreasing the clonogenic and migration potential of oral cancer cells. Moreover, silencing of Akt1 and 2 isoforms was found to decrease the expression of proteins regulating cancer cell survival and proliferation such as cyclooxygenase-2, B-cell lymphoma 2 (Bcl-2), cyclin D1, and survivin. Thus, the important role of Akt1 and 2 isoforms have been elucidated in oral cancer with in-depth mechanistic analysis.

Down-regulated HSDL2 expression suppresses cell proliferation and promotes apoptosis in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. Hydroxysteroid dehydrogenase like 2 (HSDL2) can regulate lipid metabolism and take part in cell proliferation. The purpose of the present study was to explore functional role of HSDL2 gene in PTC. The expression of HSDL2 protein in PTC tissues was estimated using immunohistochemistry analysis (IHC). HSDL2 mRNA level was detected through quantitative real-time polymerase chain reaction (qRT-PCR). Effects of HSDL2 gene on cell proliferation and apoptosis were assessed using the shRNA method for both in vitro and in vivo experiments. Potential target genes of HSDL2 were determined via bioinformatics analyses and Western blotting. HSDL2 was up-regulated in PTC tissues and cell lines compared with the controls (all P<0.05). Inhibiting HSDL expression could suppress PTC cell proliferation and cycle, and promote apoptosis in vitro. In vivo, the knockdown of HSDL2 gene could significantly suppress tumor growth (all P<0.05). Furthermore, AKT3, NFATc2 and PPP3CA genes might be potential targets of HSDL2 in PTC. HSDL2 expression was increased in PTC tissues and cells, which could promote tumor progression in vitro and in vivo.

AKT-dependent phosphorylation of the adenosine deaminases ADAR-1 and -2 inhibits deaminase activity

Murine thymoma viral oncogene homolog (AKT) kinases target both cytosolic and nuclear substrates for phosphorylation. Whereas the cytosolic substrates are known to be closely associated with the regulation of apoptosis and autophagy or metabolism and protein synthesis, the nuclear substrates are, for the most part, poorly understood. To better define the role of nuclear AKT, potential AKT substrates were isolated from the nuclear lysates of leukemic cell lines using a phosphorylated AKT substrate antibody and identified in tandem mass spectrometry. Among the proteins identified was adenosine deaminase acting on RNA (ADAR)1p110, the predominant nuclear isoform of the adenosine deaminase acting on double-stranded RNA. Coimmunoprecipitation studies and in vitro kinase assays revealed that AKT-1, -2, and -3 interact with both ADAR1p110 and ADAR2 and phosphorylate these RNA editases. Using site-directed mutagenesis of suspected AKT phosphorylation sites, AKT was found to primarily phosphorylate ADAR1p110 and ADAR2 on T738 and T553, respectively, and overexpression of the phosphomimic mutants ADAR1p110 (T738D) and ADAR2 (T553D) resulted in a 50-100% reduction in editase activity. Thus, activation of AKT has a direct and major impact on RNA editing.-Bavelloni, A., Focaccia, E., Piazzi, M., Raffini, M., Cesarini, V., Tomaselli, S., Orsini, A., Ratti, S., Faenza, I., Cocco, L., Gallo, A., Blalock, W. L. AKT-dependent phosphorylation of the adenosine deaminases ADAR-1 and -2 inhibits deaminase activity.

PASNet: pathway-associated sparse deep neural network for prognosis prediction from high-throughput data

Background

Predicting prognosis in patients from large-scale genomic data is a fundamentally challenging problem in genomic medicine. However, the prognosis still remains poor in many diseases. The poor prognosis may be caused by high complexity of biological systems, where multiple biological components and their hierarchical relationships are involved. Moreover, it is challenging to develop robust computational solutions with high-dimension, low-sample size data.

Results

In this study, we propose a Pathway-Associated Sparse Deep Neural Network (PASNet) that not only predicts patients’ prognoses but also describes complex biological processes regarding biological pathways for prognosis. PASNet models a multilayered, hierarchical biological system of genes and pathways to predict clinical outcomes by leveraging deep learning. The sparse solution of PASNet provides the capability of model interpretability that most conventional fully-connected neural networks lack. We applied PASNet for long-term survival prediction in Glioblastoma multiforme (GBM), which is a primary brain cancer that shows poor prognostic performance. The predictive performance of PASNet was evaluated with multiple cross-validation experiments. PASNet showed a higher Area Under the Curve (AUC) and F1-score than previous long-term survival prediction classifiers, and the significance of PASNet’s performance was assessed by Wilcoxon signed-rank test. Furthermore, the biological pathways, found in PASNet, were referred to as significant pathways in GBM in previous biology and medicine research.

Conclusions

PASNet can describe the different biological systems of clinical outcomes for prognostic prediction as well as predicting prognosis more accurately than the current state-of-the-art methods. PASNet is the first pathway-based deep neural network that represents hierarchical representations of genes and pathways and their nonlinear effects, to the best of our knowledge. Additionally, PASNet would be promising due to its flexible model representation and interpretability, embodying the strengths of deep learning. The open-source code of PASNet is available at https://github.com/DataX-JieHao/PASNet.

Role of Akt Isoforms Controlling Cancer Stem Cell Survival, Phenotype and Self-Renewal

The cancer stem cell (CSC) hypothesis suggests that tumours are maintained by a subpopulation of cells with stem cell properties. Although the existence of CSCs was initially described in human leukaemia, less evidence exists for CSCs in solid tumours. Recently, a CD133+ cell subpopulation was isolated from human brain tumours exhibiting stem cell properties in vitro as well as the capacity to initiate tumours in vivo. In the present work, we try to summarize the data showing that some elements of the Phosphoinositide 3-kinase Class I (PI3K)/ Thymoma viral oncogene protein kinase (Akt) pathway, such the activity of PI3K Class I or Akt2, are necessary to maintain the CSC-like phenotype as well as survival of CSCs (also denoted as tumour-initiating cells (TICs)). Our data and other laboratory data permit a working hypothesis in which each Akt isoform plays an important and specific role in CSC/TIC growth, self-renewal, maintaining survival, and epithelial-mesenchymal transition (EMT) phenotype, not only in breast cancer, but also in glioma. We suggest that a more complete understanding is needed of the possible roles of isoforms in human tumours (iso-signalling determination). Thus, a comprehensive analysis of how hierarchical signalling is assembled during oncogenesis, how cancer landmarks are interconnected to favour CSC and tumour growth, and how some protein isoforms play a specific role in CSCs to ensure that survival and proliferation must be done in order to propose/generate new therapeutic approaches (alone or in combination with existing ones) to use against cancer.

Ouabain suppresses the growth and migration abilities of glioma U‑87MG cells through inhibiting the Akt/mTOR signaling pathway and downregulating the expression of HIF‑1α

Glioma is one of the most malignant forms of brain tumor, and has been of persistent concern due to its high recurrence and mortality rates, and limited therapeutic options. As a cardiac glycoside, ouabain has widespread applications in congestive heart diseases due to its positive cardiac inotropic effect by inhibiting Na⁺/K⁺-ATPase. Previous studies have demonstrated that ouabain has antitumor activity in several types of human tumor, including glioma. However, the exact underlying mechanism remains to be elucidated. The purpose of present study was to elucidate the effect of ouabain on human glioma cell apoptosis and investigate the exact mechanism. U-87MG cells were treated with various concentrations of ouabain for 24 h, following which cell viability and survival rate were assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The dynamic changes and cell motility were observed using digital holographic microscopy. Additionally, western blot analysis and high-content screening assays were used to detect the protein expression levels of phosphorylated (p-)Akt, mammalian target of rapamycin (mTOR), p-mTOR and hypoxia-inducible factor (HIF)-1α, respectively. Compared with the control group, ouabain suppressed U-87MG cell survival, and attenuated cell motility in a dose-dependent manner (P<0.01). The downregulation of p-Akt, mTOR, p-mTOR and HIF-1α were observed following treatment with 2.5 and 25 µmol/l of ouabain. These results suggested that ouabain exerted suppressive effects on tumor cell growth and motility, leading to cell death via regulating the intracellular Akt/mTOR signaling pathway and inhibiting the expression of HIF-1α in glioma cells. The present study examined the mechanism underlying the antitumor property of ouabain, providing a novel potential therapeutic agent for glioma treatment.

Testicular orphan receptor 4 promotes tumor progression and implies poor survival through AKT3 regulation in seminoma

Seminoma is the most common testicular germ cell tumor worldwide and mainly occurs in 15-35-year-old young men. Early studies have indicated that testicular nuclear receptor 4 (TR4) first cloned from testis is involved in the invasion and metastasis of several human tumors; however, little attention is paid to the function of TR4 in seminoma. Our immunohistochemical (IHC) staining results showed that patients with advanced stage tumors tended to have higher expression of TR4. Importantly, there was a significant association between elevated TR4 expression and reduced overall survival in seminoma patients. In vitro MTS, western blot and transwell assays, after manipulating TR4 expression in Tcam-2 cells, revealed that TR4 induced epithelial-to-mesenchymal transition (EMT) and promoted Tcam-2 cell proliferation and invasion. Mechanism dissection demonstrated that AKT3, a critical component in the signaling pathway, played a crucial role in mediating TR4-promoted Tcam-2 cell proliferation and invasion. We further revealed that TR4 modulated AKT3 at the transcriptional level via chromatin immunoprecipitation and luciferase assays. Meanwhile, addition of the AKT3 siRNA blocked the function of TR4. Overall, these findings first elucidate that TR4 is a novel prognostic marker and plays a critical role in the metastatic capacity of Tcam-2 cells by EMT regulation and, consequently, targeting TR4-AKT3 pathway may serve as a potential therapeutic approach for seminoma.

The allosteric AKT inhibitor MK2206 shows a synergistic interaction with chemotherapy and radiotherapy in glioblastoma spheroid cultures

BACKGROUND

Glioblastoma multiforme (GBM) is the most common, invasive and deadly primary type of malignant brain tumor. The Phosphatidylinositol-3-Kinase/AKT (PI3K/AKT) pathway is highly active in GBM and has been associated with increased survival and resistance to therapy. The aim of this study is to investigate the effects of AKT inhibition in combination with the current standard of care which consists of irradiation and temozolomide (TMZ) on human malignant glioma cells growing adherent and as multicellular spheroids in vitro.

METHODS

The effects of the allosteric inhibitor MK2206 combined with irradiation and TMZ were assessed on glioma cells growing adherent and as multicellular 3D spheroids. The interaction was studied on proliferation, clonogenic cell survival, cell invasion, -migration and on expression of key proteins in the PI3K-AKT pathway by western blot.

RESULTS

A differential effect was found at low- (1 μM) and high dose (10 μM) MK2206. At 1 μM, the inhibitor reduced phosphorylation of Thr308 and Ser473 residues of AKT in both adherent cells and spheroids. Low dose MK2206 delayed spheroid growth and sensitized spheroids to both irradiation and TMZ in a synergistic way (Combination index <0.35). In contrast, neither low nor high dose MK2206 did enhance therapy sensitivity in adherent growing cells. Effective inhibition of invasion and migration was observed only at higher doses of MK2206 (>5 μM).

CONCLUSIONS

The data show that a 3D spheroid model show different sensitivity to irradiation when combined with AKT inhibition. Thereby we show that MK2206 has potential synergistic efficacy to the current standard of care for glioma patients.

Regulation of PI3K effector signalling in cancer by the phosphoinositide phosphatases

Class I phosphoinositide 3-kinase (PI3K) generates phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P₃) at the plasma membrane in response to growth factors, activating a signalling cascade that regulates many cellular functions including cell growth, proliferation, survival, migration and metabolism. The PI3K pathway is commonly dysregulated in human cancer, and drives tumorigenesis by promoting aberrant cell growth and transformation. PtdIns(3,4,5)P₃ facilitates the activation of many pleckstrin homology (PH) domain-containing proteins including the serine/threonine kinase AKT. There are three AKT isoforms that are frequently hyperactivated in cancer through mutation, amplification or dysregulation of upstream regulatory proteins. AKT isoforms have converging and opposing functions in tumorigenesis. PtdIns(3,4,5)P₃ signalling is degraded and terminated by phosphoinositide phosphatases such as phosphatase and tensin homologue (PTEN), proline-rich inositol polyphosphate 5-phosphatase (PIPP) (INPP5J) and inositol polyphosphate 4-phosphatase type II (INPP4B). PtdIns(3,4,5)P₃ is rapidly hydrolysed by PIPP to generate phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P₂), which is further hydrolysed by INPP4B to form phosphatidylinositol 3-phosphate (PtdIns3P). PtdIns(3,4)P₂ and PtdIns3P are also important signalling molecules; PtdIns(3,4)P₂ together with PtdIns(3,4,5)P₃ are required for maximal AKT activation and PtdIns3P activates PI3K-dependent serum and glucocorticoid-regulated kinase (SGK3) signalling. Loss of Pten, Pipp or Inpp4b expression or function promotes tumour growth in murine cancer models through enhanced AKT isoform-specific signalling. INPP4B inhibits PtdIns(3,4)P₂-mediated AKT activation in breast and prostate cancer; however, INPP4B expression is increased in acute myeloid leukaemia (AML), melanoma and colon cancer where it paradoxically promotes cell proliferation, transformation and/or drug resistance. This review will discuss how PTEN, PIPP and INPP4B distinctly regulate PtdIns(3,4,5)P₃ signalling downstream of PI3K and how dysregulation of these phosphatases affects cancer outcomes.