Gene Summary

Gene:AXL; AXL receptor tyrosine kinase
Aliases: ARK, UFO, JTK11, Tyro7
Summary:The protein encoded by this gene is a member of the Tyro3-Axl-Mer (TAM) receptor tyrosine kinase subfamily. The encoded protein possesses an extracellular domain which is composed of two immunoglobulin-like motifs at the N-terminal, followed by two fibronectin type-III motifs. It transduces signals from the extracellular matrix into the cytoplasm by binding to the vitamin K-dependent protein growth arrest-specific 6 (Gas6). This gene may be involved in several cellular functions including growth, migration, aggregation and anti-inflammation in multiple cell types. Alternative splicing results in multiple transcript variants of this gene. [provided by RefSeq, Jul 2013]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:tyrosine-protein kinase receptor UFO
Source:NCBIAccessed: 30 August, 2019


What does this gene/protein do?
Show (39)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 30 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Phosphorylation
  • Apoptosis
  • Protein Kinase Inhibitors
  • Antineoplastic Agents
  • Gene Expression Profiling
  • AXL
  • Ovarian Cancer
  • Cell Proliferation
  • Vascular Endothelial Growth Factor Receptor-2
  • Non-Small Cell Lung Cancer
  • Lung Cancer
  • Neoplastic Cell Transformation
  • Neoplasm Invasiveness
  • Gene Expression
  • Intercellular Signaling Peptides and Proteins
  • Adenocarcinoma
  • Epithelial-Mesenchymal Transition
  • Cell Movement
  • Messenger RNA
  • Base Sequence
  • IGF1R
  • Drug Resistance
  • Quinazolines
  • Breast Cancer
  • siRNA
  • Platelet-Derived Growth Factor Receptors
  • Chromosome 19
  • MicroRNAs
  • Molecular Targeted Therapy
  • Biomarkers, Tumor
  • Melanoma
  • c-MET
  • ErbB Receptors
  • Immunohistochemistry
  • Mutation
  • Proto-Oncogene Proteins
  • Neoplasm Metastasis
  • Cancer Gene Expression Regulation
  • RNA Interference
  • Thyroid Cancer
  • Oncogene Proteins
  • Cell Survival
Tag cloud generated 30 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: AXL (cancer-related)

Duan Y, Luo L, Qiao C, et al.
A novel human anti-AXL monoclonal antibody attenuates tumour cell migration.
Scand J Immunol. 2019; 90(2):e12777 [PubMed] Related Publications
TAM family members (TYRO3, AXL and MERTK) play essential roles in the resolution of inflammation and in infectious diseases and cancer. AXL, a tyrosine kinase receptor, is commonly overexpressed in several solid tumours and numerous hematopoietic malignancies including acute myeloid leukaemia, acute lymphocytic leukaemia, chronic myeloid leukaemia, chronic lymphocytic leukaemia and multiple myeloma. AXL significantly promotes tumour cell migration, invasion and metastasis, as well as angiogenesis. AXL also plays an important role in inflammation and macrophage ontogeny. Recent studies have revealed that AXL contributes to leukaemic phenotypes through activation of oncogenic signalling pathways that lead to increased cell migration and proliferation. To evaluate the mechanisms underlying the role of AXL signalling in tumour metastasis, we screened a phage display library to generate a novel human monoclonal antibody, named DAXL-88, that recognizes both human and murine AXL. The concentrations of DAXL-88 required for 50% maximal binding to human and murine AXL were 0.118 and 0.164 μg/mL, respectively. Furthermore, DAXL-88 bound to human AXL with high affinity (K

Alonso-Gordoa T, García-Bermejo ML, Grande E, et al.
Targeting Tyrosine kinases in Renal Cell Carcinoma: "New Bullets against Old Guys".
Int J Mol Sci. 2019; 20(8) [PubMed] Free Access to Full Article Related Publications
Clear cell renal cell carcinoma (ccRCC) is the seventh most frequently diagnosed tumor in adults in Europe and represents approximately 2.5% of cancer deaths. The molecular biology underlying renal cell carcinoma (RCC) development and progression has been a key milestone in the management of this type of tumor. The discovery of Von Hippel Lindau (

Lee MJ, Tsai YJ, Lin MY, et al.
Calebin-A induced death of malignant peripheral nerve sheath tumor cells by activation of histone acetyltransferase.
Phytomedicine. 2019; 57:377-384 [PubMed] Related Publications
BACKGROUND: Neurofibromatosis type 1 (NF1) is one of the most common hereditary neurocutaneous disorders. The malignant peripheral nerve sheath tumor (MPNST), transformed from NF1 related plexiform neurofibroma, is a rapidly growing and highly invasive tumor. No effective chemotherapeutic agent is currently available. Calebin-A is a derivative from turmeric Curcuma longa. Given the anti-inflammatory and anticancer potentials of curcumin, whether Calebin-A also had the tumoricidal effect upon MPNST cells is still elusive.
PURPOSE: To determine whether Calebin-A has the potential for anti-MPNST effect.
METHODS: The MTT and FACS analysis of normal Schwann (HSC) and MPNST cells have been employed to determine the tumoricidal effect of Calebin-A. The expression of the signal pathway molecules was assessed by Western blotting. The CHIP with quantitative PCR assay was performed to quantify the promoter DNA binding to acetylated histone 3 (acetyl H3). The enzyme activities of histone acetyltransferase (HAT) and deacetylase (HDAC) have been evaluated by commercial kits. The measurements of tumor size of the xenograft mouse model were also performed.
RESULTS: Calebin-A inhibited the proliferation of MPNST and primary neurofibroma cells in a dose-dependent manner. The flow cytometry analysis of the MPNST cells after treatment of 25 μm of Calebin-A demonstrated an increase of population in the G0/G1 phase but decrease in G2/M phase. Before treatment, the expression of Axl, Tyro3, and acetyl H3 was significantly higher in MPNST cells when compared to HSC. The expression of phosphorylated-AKT, -ERK1/2, survivin, hTERT, and acetyl H3 proteins were reduced after treatment. The CHIP assay shows the promoter DNA copies of survivin (BRIC5) and hTERT genes are significantly reduced post-treatment. The enzyme activity of HAT was significantly reduced, but not that of HDAC. Two HAT inhibitors, epigallocatechin-3-gallate (EGCG) and anacardic acid (AA) have also demonstrated a significant inhibitory effect on MPNST cells. Finally, the measurements of tumor size showed a significant reduction of the xenograft tumors after treatment of Calebin-A.
CONCLUSION: Both in vitro and in vivo studies showed Calebin-A could inhibit the proliferation of MPNST with suppression of survivin and hTERT. The reduced expression of these two factors might be through the epigenetic histone modification resulting from the decreased activity of HAT.

Lee YJ, Kim SY, Lee C
Axl is a novel target of celastrol that inhibits cell proliferation and migration, and increases the cytotoxicity of gefitinib in EGFR mutant non‑small cell lung cancer cells.
Mol Med Rep. 2019; 19(4):3230-3236 [PubMed] Related Publications
Gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR‑TKI) is an excellent therapeutic agent to treat EGFR mutation‑positive non‑small cell lung cancer (NSCLC). However, the initial response decreases as chemoresistance develops. In the present study, gefitinib‑resistant EGFR mutant NSCLC PC‑9/GR cells were established to examine the characteristics and mechanisms associated with chemoresistance. Axl expression in PC‑9/GR cells was transcriptionally upregulated, since Axl protein and mRNA expression levels were identified to be increased according to western blot analysis and reverse transcription polymerase chain reaction results. The inhibitory effect of celastrol on Axl protein expression level, cell viability and clonogenicity were identified in parental and gefitinib‑resistant PC‑9 cells. In addition, treatment of PC‑9/GR cells with celastrol and gefitinib in combination was demonstrated to synergistically suppress Axl protein expression level, cell proliferation and migration. Taken together, upregulation of Axl expression seems to be associated with chemoresistance of PC‑9/GR cells. Furthermore, celastrol targets Axl to exert its anticancer effects in order to increase the susceptibility of PC‑9/GR cells to gefitinib and overcome chemoresistance.

Tsukita Y, Fujino N, Miyauchi E, et al.
Axl kinase drives immune checkpoint and chemokine signalling pathways in lung adenocarcinomas.
Mol Cancer. 2019; 18(1):24 [PubMed] Free Access to Full Article Related Publications
Axl receptor tyrosine kinase is involved in the growth and metastasis and is an indicator of poor prognosis in several cancers including lung cancers. Although a mitogen-activated protein kinase (MAPK) pathway and an epithelial-to-mesenchymal transition (EMT) program are critical, molecular mechanisms underlying the Axl-driven cancer progression have not been fully elucidated. We aimed to identify molecules up-regulated by Axl kinase in lung adenocarcinomas. Through the global gene expression analysis and the functional annotation clustering, we found that AXL expression positively correlated with mRNA expressions of immune checkpoint molecules and chemokine receptors in non-small-cell lung cancers. Validation cohorts including our biobank confirmed that the AXL expression significantly correlated with expression of genes encoding programmed death-ligand1 (PD-L1) and CXC chemokine receptor 6 (CXCR6) in lung adenocarcinoma, especially in epidermal growth factor receptor (EGFR) mutation-positive adenocarcinoma. Pharmacological inhibition of Axl kinase activity decreased mRNA expressions of PD-L1 and CXCR6 in EGFR mutation-positive cell lines. Our data indicates the novel role of Axl kinase as a driver of immune checkpoint molecules and chemokine signalling pathways in the progression of lung adenocarcinomas. This study also highlights the necessity of clinical trials in order to test the efficacy of Axl kinase inhibition in the Axl-highly expressing subset of lung adenocarcinomas. .

Zhang P, Dong Q, Zhu H, et al.
Long non-coding antisense RNA GAS6-AS1 supports gastric cancer progression via increasing GAS6 expression.
Gene. 2019; 696:1-9 [PubMed] Related Publications
OBJECTIVE: As one broader class of non-coding RNAs (lncRNAs), non-coding antisense (AS) transcripts are functionally characterized to play pivotal roles in various pathophysiological processes, including tumor biology.
METHODS: In this study, the exact biological functions and regulation mechanisms of GAS6-AS1 in gastric cancer (GC) was examined.
RESULTS: The expression of GAS6-AS1 was markedly upregulated in GC tissues and is associated with advanced stage (III + IV) of GC patients. Gain-of-function and loss-of-function experiments showed that GAS6-AS1 promoted cell proliferation, migration, invasion ability in vitro and xenograft tumor growth in vivo by promoting entry into S-phase. The mechanistic investigations showed that GAS6-AS1 can control the expression of its cognate sense gene GAS6 at the transcriptional or translational levels by forming a RNA-RNA duplex, consequently inducing an increase of AXL level and driveling AXL signaling pathway activation.
CONCLUSIONS: Taken together, our studies indicate that GAS6-AS1 significantly driving the aggressive phenotype in GC through activating its cognate sense gene GAS6, and provides a more complete understanding of GAS6-AS1 as a potential therapeutic target for GC.

Taniguchi H, Yamada T, Wang R, et al.
AXL confers intrinsic resistance to osimertinib and advances the emergence of tolerant cells.
Nat Commun. 2019; 10(1):259 [PubMed] Free Access to Full Article Related Publications
A novel EGFR-tyrosine kinase inhibitor (TKI), osimertinib, has marked efficacy in patients with EGFR-mutated lung cancer. However, some patients show intrinsic resistance and an insufficient response to osimertinib. This study showed that osimertinib stimulated AXL by inhibiting a negative feedback loop. Activated AXL was associated with EGFR and HER3 in maintaining cell survival and inducing the emergence of cells tolerant to osimertinib. AXL inhibition reduced the viability of EGFR-mutated lung cancer cells overexpressing AXL that were exposed to osimertinib. The addition of an AXL inhibitor during either the initial or tolerant phases reduced tumor size and delayed tumor re-growth compared to osimertinib alone. AXL was highly expressed in clinical specimens of EGFR-mutated lung cancers and its high expression was associated with a low response rate to EGFR-TKI. These results indicated pivotal roles for AXL and its inhibition in the intrinsic resistance to osimertinib and the emergence of osimertinib-tolerant cells.

Niu ZS, Niu XJ, Wang WH
Role of the receptor tyrosine kinase Axl in hepatocellular carcinoma and its clinical relevance.
Future Oncol. 2019; 15(6):653-662 [PubMed] Related Publications
The receptor tyrosine kinase Axl and its ligand Gas6 regulate fundamental biological processes, including cell proliferation, survival and motility, through multiple downstream signaling pathways. Evidence to date suggests that aberrant Axl expression frequently occurs in many malignancies, including hepatocellular carcinoma, and that this is critical for promoting cell proliferation, migration, angiogenesis and metastasis. Moreover, deregulated Axl expression or activation is reportedly associated with resistance to cancer drugs and targeted cancer therapies. Thus, Axl inhibitors may represent a novel therapeutic approach for cancer treatment. This Review summarizes the latest advances concerning the biological role of Axl in hepatocellular carcinoma and its potential clinical relevance.

Tièche CC, Gao Y, Bührer ED, et al.
Tumor Initiation Capacity and Therapy Resistance Are Differential Features of EMT-Related Subpopulations in the NSCLC Cell Line A549.
Neoplasia. 2019; 21(2):185-196 [PubMed] Free Access to Full Article Related Publications
Cell lines are essential tools to standardize and compare experimental findings in basic and translational cancer research. The current dogma states that cancer stem cells feature an increased tumor initiation capacity and are also chemoresistant. Here, we identified and comprehensively characterized three morphologically distinct cellular subtypes in the non-small cell lung cancer cell line A549 and challenge the current cancer stem cell dogma. Subtype-specific cellular morphology is maintained during short-term culturing, resulting in the formation of holoclonal, meroclonal, and paraclonal colonies. A549 holoclone cells were characterized by an epithelial and stem-like phenotype, paraclone cells featured a mesenchymal phenotype, whereas meroclone cells were phenotypically intermediate. Cell-surface marker expression of subpopulations changed over time, indicating an active epithelial-to-mesenchymal transition (EMT), in vitro and in vivo. EMT has been associated with the overexpression of the immunomodulators PD-L1 and PD-L2, which were 37- and 235-fold overexpressed in para- versus holoclone cells, respectively. We found that DNA methylation is involved in epigenetic regulation of marker expression. Holoclone cells were extremely sensitive to cisplatin and radiotherapy in vitro, whereas paraclone cells were highly resistant. However, inhibition of the receptor tyrosine kinase AXL, whose expression is associated with an EMT, specifically targeted the otherwise highly resistant paraclone cells. Xenograft tumor formation capacity was 24- and 269-fold higher in holo- than mero- and paraclone cells, respectively. Our results show that A549 subpopulations might serve as a unique system to explore the network of stemness, cellular plasticity, tumor initiation capacity, invasive and metastatic potential, and chemo/radiotherapy resistance.

Yu S, Ren H, Li Y, et al.
HOXA4-Dependent Transcriptional Activation of AXL Promotes Cisplatin- Resistance in Lung Adenocarcinoma Cells.
Anticancer Agents Med Chem. 2018; 18(14):2062-2067 [PubMed] Related Publications
BACKGROUND: Lung cancer is one of the most leading causes of cancer-related deaths in adults worldwide. Non-Small Cell Lung Cancer (NSCLC), which comprises 80 to 85% of all lung cancers, is the most lethal subtype of lung cancer with a 5-year survival of less than 13%. In this study, we identified a poorly-studied kinase PDK4 as the most up-regulated kinase encoding gene in Cisplatin resistant lung adenocarcinoma.
METHODS: In vitro cell viability assay and in vivo tumor xenograft assay were used in the detection of cell proliferation. RNA isolation, quantitative Real-Time PCR, Western blot analysis, immunohistochemistry were used to investigate the expression of RNA and protein. Lentivirus infection was used to regulate gene expression. Luciferase assays were used to monitor EPAS1 promoter activity.
RESULTS: In vivo PDK4 expression was elevated in a Cisplatin-resistant population of lung adenocarcinoma cells, PDK4-dependent Cisplatin-resistance promotes tumor growth of lung adenocarcinoma in vivo and in vitro, clinically PDK4 expression was associated with poor prognosis in lung adenocarcinoma patients, mechanically PDK4 promoted cell growth and Cisplatin-resistance of lung adenocarcinoma via transcriptional regulation of endothelial PAS domain-containing protein 1 (EPAS1).
CONCLUSION: PDK4 is the most up-regulated kinase encoding gene in Cisplatin resistant lung adenocarcinoma and PDK4-dependent Cisplatin-resistance promotes tumor growth of lung adenocarcinoma mainly through transcriptional regulation of EPAS1. Enriched PDK4 expression was correlated with the poor prognosis of lung cancer patients, indicating that PDK4 could be a potential therapeutic target for Cisplatin-resistant lung adenocarcinoma.

Tulchinsky E, Demidov O, Kriajevska M, et al.
EMT: A mechanism for escape from EGFR-targeted therapy in lung cancer.
Biochim Biophys Acta Rev Cancer. 2019; 1871(1):29-39 [PubMed] Related Publications
Epithelial mesenchymal transition (EMT) is a reversible developmental genetic programme of transdifferentiation of polarised epithelial cells to mesenchymal cells. In cancer, EMT is an important factor of tumour cell plasticity and has received increasing attention for its role in the resistance to conventional and targeted therapies. In this paper we provide an overview of EMT in human malignancies, and discuss contribution of EMT to the development of the resistance to Epidermal Growth Factor Receptor (EGFR)-targeted therapies in non-small cell lung cancer (NSCLC). Patients with the tumours bearing specific mutations in EGFR have a good clinical response to selective EGFR inhibitors, but the resistance inevitably develops. Several mechanisms responsible for the resistance include secondary mutations in the EGFR gene, genetic or non-mutational activation of alternative survival pathways, transdifferentiation of NSCLC to the small cell lung cancer histotype, or formation of resistant tumours with mesenchymal characteristics. Mechanistically, application of an EGFR inhibitor does not kill all cancer cells; some cells survive the exposure to a drug, and undergo genetic evolution towards resistance. Here, we present a theory that these quiescent or slow-proliferating drug-tolerant cell populations, or so-called "persisters", are generated via EMT pathways. We review the EMT-activated mechanisms of cell survival in NSCLC, which include activation of ABC transporters and EMT-associated receptor tyrosine kinase AXL, immune evasion, and epigenetic reprogramming. We propose that therapeutic inhibition of these pathways would eliminate pools of persister cells and prevent or delay cancer recurrence when applied in combination with the agents targeting EGFR.

Hajalirezay Yazdi S, Paryan M, Mohammadi-Yeganeh S
An integrated approach of bioinformatic prediction and in vitro analysis identified that miR-34a targets
Cell Mol Biol Lett. 2018; 23:51 [PubMed] Free Access to Full Article Related Publications
Background: Breast cancer is the most prevalent cancer among women, and
Methods: Bioinformatic approaches were used to find a miRNA that simultaneously targets both
Results: By applying bioinformatic software and programs, miRNAs that target the 3'-UTR of both
Conclusions: These findings may indicate that miR-34a is an oncogenic miRNA, downregulated in the distinct breast cancer subtypes. It also targets

Hong J, Maacha S, Belkhiri A
Transcriptional upregulation of c-MYC by AXL confers epirubicin resistance in esophageal adenocarcinoma.
Mol Oncol. 2018; 12(12):2191-2208 [PubMed] Free Access to Full Article Related Publications
AXL receptor tyrosine kinase is overexpressed in esophageal adenocarcinoma (EAC) and several other types of malignancies; hence, it may be a valuable therapeutic target. Herein, we investigated the role of AXL in regulating c-MYC expression and resistance to the chemotherapeutic agent epirubicin in EAC. Using in vitro EAC cell models, we found that AXL overexpression enhances epirubicin resistance in sensitive cells. Conversely, genetic knockdown or pharmacological inhibition of AXL sensitizes resistant cells to epirubicin. Notably, we showed that inhibition or knockdown of c-MYC markedly sensitizes AXL-dependent resistant cells to epirubicin, and our data demonstrated that AXL promotes epirubicin resistance through transcriptional upregulation of c-MYC. We showed that AXL overexpression significantly increased transcriptional activity, mRNA, and protein levels of c-MYC. Conversely, AXL knockdown reversed these effects. Mechanistic investigations indicated that AXL upregulates c-MYC expression through activation of the AKT/β-catenin signaling pathway. Data from a tumor xenograft mouse model indicated that inhibition of AXL with R428 in combination with epirubicin synergistically suppresses tumor growth and proliferation. Our results demonstrate that AXL promotes epirubicin resistance through transcriptional upregulation of c-MYC in EAC. Our findings support future clinical trials to assess the therapeutic potential of R428 in epirubicin-resistant tumors with overexpression of AXL and activation of c-MYC.

Smith MP, Rana S, Ferguson J, et al.
A PAX3/BRN2 rheostat controls the dynamics of BRAF mediated MITF regulation in MITF
Pigment Cell Melanoma Res. 2019; 32(2):280-291 [PubMed] Free Access to Full Article Related Publications
The BRAF kinase and the MAPK pathway are targets of current melanoma therapies. However, MAPK pathway inhibition results in dynamic changes of downstream targets that can counteract inhibitor-action not only in during treatment, but also in acquired resistant tumours. One such dynamic change involves the expression of the transcription factor MITF, a crucial regulator of cell survival and proliferation in untreated as well as drug-addicted acquired resistant melanoma. Tight control over MITF expression levels is required for optimal melanoma growth, and while it is well established that the MAPK pathway regulates MITF expression, the actual mechanism is insufficiently understood. We reveal here, how BRAF through action on the transcription factors BRN2 and PAX3 executes control over the regulation of MITF expression in a manner that allows for considerable plasticity. This plasticity provides robustness to the BRAF mediated MITF regulation and explains the dynamics in MITF expression that are observed in patients in response to MAPK inhibitor therapy.

Hua W, Zhao Y, Jin X, et al.
METTL3 promotes ovarian carcinoma growth and invasion through the regulation of AXL translation and epithelial to mesenchymal transition.
Gynecol Oncol. 2018; 151(2):356-365 [PubMed] Related Publications
OBJECTIVE: As the most prevalent internal modification in mammalian messenger RNA, N
METHODS: METTL3 expression was assessed by immunohistochemistry in 162 ovarian carcinoma patients. Stable cell lines with METTL3 gene overexpression or knockdown were established to investigate the function of METTL3 in ovarian cancer in vitro and in vivo.
RESULTS: METTL3 was frequently upregulated in ovarian carcinoma and that a high level of METTL3 was significantly associated with tumor grade (P = 0.001), pT status (P = 0.002), pN/pM status (P < 0.001), FIGO stage (P < 0.001), and overall survival rate (P < 0.001). Stable overexpression of METTL3 in the OVCAR3 and COV504 cell lines significantly increased cellular proliferation, focus formation, motility, invasion, and tumor formation in nude mice. Silencing METTL3 expression in the SKOV3 and HO-8910 cell lines with short hairpin RNA effectively inhibited its oncogenic function. Further study found that METTL3 promoted epithelial-mesenchymal transition (EMT) by upregulating the receptor tyrosine kinase AXL.
CONCLUSION: Our findings suggest that METTL3 plays very important oncogenic roles in ovarian carcinoma development and/or aggressiveness by stimulating AXL translation and EMT and that METTL3 may serve as a novel prognostic and/or therapeutic target of interest in ovarian cancer.

Li YY, Tao YW, Gao S, et al.
Cancer-associated fibroblasts contribute to oral cancer cells proliferation and metastasis via exosome-mediated paracrine miR-34a-5p.
EBioMedicine. 2018; 36:209-220 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Cancer-associated fibroblasts (CAFs) play an important role in regulating tumor progression by transferring exosomes to neighboring cells. Our aim was to clarify the role of microRNA encapsulated in the exosomes derived from CAFs in oral squamous cell carcinoma (OSCC).
METHODS: We examined the microRNA expression profiles of exosomes derived from CAFs and donor-matched normal fibroblasts (NFs) from patients with OSCC. We used confocal microscopy to examine the transportation of exosomal miR-34a-5p between CAFs and OSCC cells. Next, luciferase reporter and its mutant plasmids were used to confirm direct target gene of miR-34a-5p. Phenotypic assays and in vivo tumor growth experiments were used to investigate the functional significance of exosomal miR-34a-5p.
FINDINGS: We found that the expression of miR-34a-5p in CAF-derived exosomes was significantly reduced, and fibroblasts could transfer exosomal miR-34a-5p to OSCC cells. In xenograft experiments, miR-34a-5p overexpression in CAFs could inhibit the tumorigenesis of OSCC cells. We further revealed that miR-34a-5p binds to its direct downstream target AXL to suppress OSCC cell proliferation and metastasis. Stable ectopic expression of AXL in OSCC cells overexpressing miR-34a-5p restored proliferation and motility abolished by the miRNA. The miR-34a-5p/AXL axis promoted OSCC progression via the AKT/GSK-3β/β-catenin signaling pathway, which could induce the epithelial-mesenchymal transition (EMT) to promote cancer cells metastasis. The miR-34a-5p/AXL axis enhanced nuclear translocation of β-catenin and then induced transcriptional upregulation of SNAIL, which in turn activated both MMP-2 and MMP-9.
INTERPRETATION: The miR-34a-5p/AXL axis confers aggressiveness in oral cancer cells through the AKT/GSK-3β/β-catenin/Snail signaling cascade and might represent a therapeutic target for OSCC. FUND: National Natural Science Foundation of China.

Tan TZ, Rouanne M, Tan KT, et al.
Molecular Subtypes of Urothelial Bladder Cancer: Results from a Meta-cohort Analysis of 2411 Tumors.
Eur Urol. 2019; 75(3):423-432 [PubMed] Related Publications
BACKGROUND: Previous molecular subtyping for bladder carcinoma (BLCA) involved <450 samples, with diverse classifications.
OBJECTIVE: To identify molecular subtypes by curating a large BLCA dataset.
DESIGN, SETTING, AND PARTICIPANTS: Gene expression publicly available were combined and reanalyzed. The dataset contained 2411 unique tumors encompassing non-muscle-invasive (NMIBC) and muscle-invasive BLCA (MIBC). Subtypes were reproduced on The Cancer Genome Atlas, UROMOL, and IMvigor210.
INTERVENTION: Subtypes were assigned by gene expression.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Kaplan-Meier analyses were performed for subtype-clinical outcome correlations; Chi-square/Fisher exact tests were used for subtype-clinicopathological parameters associations.
RESULTS AND LIMITATIONS: We identified six molecular subtypes with different overall survival (OS) and molecular features. Subtype Neural-like (median OS, 87 mo) is prevalent in MIBC and characterized by high WNT/β-catenin signaling. HER2-like (107.7 mo) is distributed evenly across NMIBC and MIBC, with higher ERBB2 amplification and signaling. Papillary-like (>135 mo), an NMIBC subtype enriched in urothelial differentiation genes, shows a high frequency of actionable FGFR3 mutations, amplifications, and FGFR3-TACC3 fusion. Luminal-like (91.7 mo), predominantly NMIBC, has higher MAPK signaling and more KRAS and KMT2C/D mutations than other subtypes. Mesenchymal-like (MES; 86.6 mo) and Squamous-cell carcinoma-like (SCC; 20.6 mo) are predominant in MIBC. MES is high in AXL signaling, whereas SCC has elevated PD1, CTLA4 signaling, and macrophage M2 infiltration. About 20% of NMIBCs show MIBC subtype traits and a lower 5-yr OS rate than Papillary-like NMIBC (81% vs 96%). The main limitations of our study are the incomplete clinical annotation, and the analyses were based on transcriptome subset due to comparisons across gene expression quantification technologies.
CONCLUSIONS: BLCA can be stratified into six molecular subtypes. NMIBC, with a high risk of progression, displays the molecular features of MIBC.
PATIENT SUMMARY: Biomarkers are urgently needed to guide patient treatment selection and avoid unnecessary toxicities in those who fail to respond. We believe molecular subtyping is a promising way to tailor disease management for those who will benefit most.

Maacha S, Hong J, von Lersner A, et al.
AXL Mediates Esophageal Adenocarcinoma Cell Invasion through Regulation of Extracellular Acidification and Lysosome Trafficking.
Neoplasia. 2018; 20(10):1008-1022 [PubMed] Free Access to Full Article Related Publications
Esophageal adenocarcinoma (EAC) is a highly aggressive malignancy that is characterized by resistance to chemotherapy and a poor clinical outcome. The overexpression of the receptor tyrosine kinase AXL is frequently associated with unfavorable prognosis in EAC. Although it is well documented that AXL mediates cancer cell invasion as a downstream effector of epithelial-to-mesenchymal transition, the precise molecular mechanism underlying this process is not completely understood. Herein, we demonstrate for the first time that AXL mediates cell invasion through the regulation of lysosomes peripheral distribution and cathepsin B secretion in EAC cell lines. Furthermore, we show that AXL-dependent peripheral distribution of lysosomes and cell invasion are mediated by extracellular acidification, which is potentiated by AXL-induced secretion of lactate through AKT-NF-κB-dependent MCT-1 regulation. Our novel mechanistic findings support future clinical studies to evaluate the therapeutic potential of the AXL inhibitor R428 (BGB324) in highly invasive EAC.

Natarajan S, Sumantran VN, Ranganathan M, Madheswaran S
Microarray and pattern miner analysis of AXL and VIM gene networks in MDA‑MB‑231 cells.
Mol Med Rep. 2018; 18(4):4147-4155 [PubMed] Related Publications
MDA‑MB‑231 cells represent malignant triple‑negative breast cancer, which overexpress epidermal growth factor receptor (EGFR) and two genes (AXL and VIM) associated with poor prognosis. The present study aimed to identify novel therapeutic targets and elucidate the functional networks for the AXL and VIM genes in MDA‑MB‑231 cells. We identified 71 genes upregulated in MDA‑MB‑231 vs. MCF7 cells using BRB‑Array tool to re‑analyse microarray data from six GEO datasets. Gene ontology and STRING analysis showed that 43/71 genes upregulated in MDA‑MB‑231 compared with MCF7 cells, regulate cell survival and migration. Another 19 novel genes regulate migration, metastases, senescence, autophagy and chemoresistance. The Pattern Miner systems biology tool uses specific genes as inputs or 'baits' to identify outputs from the NCI‑60 database. Using five genes regulating cancer cell migration (AXL, VIM, EGFR, CAPN2, and COL4A1) as input 'baits', we used pattern miner to identify statistically significant, co‑expressed genes from the list of 71 genes upregulated in MDA‑MB‑231 compared with MCF7 cells. Outputs were subsets of the 71 genes, which showed significant co‑expression with one or more of the five input genes. These outputs were used to develop functional networks for AXL and VIM. Analysis of these networks verified known properties of AXL and VIM, and suggested novel functions for these two genes. Thus, genes in the AXL network promote migration, metastasis and chemoresistance, whereas the VIM gene network regulates novel tumorigenic processes, such as lipogenesis, senescence and autophagy. Notably, these two networks contain 12 genes not reported for TNBC.

Li W, Xiong X, Abdalla A, et al.
HGF-induced formation of the MET-AXL-ELMO2-DOCK180 complex promotes RAC1 activation, receptor clustering, and cancer cell migration and invasion.
J Biol Chem. 2018; 293(40):15397-15418 [PubMed] Article available free on PMC after 05/10/2019 Related Publications

Kato Y, Ninomiya K, Ohashi K, et al.
Combined effect of cabozantinib and gefitinib in crizotinib-resistant lung tumors harboring ROS1 fusions.
Cancer Sci. 2018; 109(10):3149-3158 [PubMed] Article available free on PMC after 05/10/2019 Related Publications
The ROS1 tyrosine kinase inhibitor (TKI) crizotinib has shown dramatic effects in patients with non-small cell lung cancer (NSCLC) harboring ROS1 fusion genes. However, patients inevitably develop resistance to this agent. Therefore, a new treatment strategy is required for lung tumors with ROS1 fusion genes. In the present study, lung cancer cell lines, HCC78 harboring SLC34A2-ROS1 and ABC-20 harboring CD74-ROS1, were used as cell line-based resistance models. Crizotinib-resistant HCC78R cells were established from HCC78. We comprehensively screened the resistant cells using a phosphor-receptor tyrosine kinase array and RNA sequence analysis by next-generation sequencing. HCC78R cells showed upregulation of HB-EGF and activation of epidermal growth factor receptor (EGFR) phosphorylation and the EGFR signaling pathway. Recombinant HB-EGF or EGF rendered HCC78 cells or ABC-20 cells resistant to crizotinib. RNA sequence analysis by next-generation sequencing revealed the upregulation of AXL in HCC78R cells. HCC78R cells showed marked sensitivity to EGFR-TKI or anti-EGFR antibody treatment in vitro. Combinations of an AXL inhibitor, cabozantinib or gilteritinib, and an EGFR-TKI were more effective against HCC78R cells than monotherapy with an EGFR-TKI or AXL inhibitor. The combination of cabozantinib and gefitinib effectively inhibited the growth of HCC78R tumors in an in vivo xenograft model of NOG mice. The results of this study indicated that HB-EGF/EGFR and AXL play roles in crizotinib resistance in lung cancers harboring ROS1 fusions. The combination of cabozantinib and EGFR-TKI may represent a useful alternative treatment strategy for patients with advanced NSCLC harboring ROS1 fusion genes.

Cañadas I, Thummalapalli R, Kim JW, et al.
Tumor innate immunity primed by specific interferon-stimulated endogenous retroviruses.
Nat Med. 2018; 24(8):1143-1150 [PubMed] Article available free on PMC after 05/10/2019 Related Publications
Mesenchymal tumor subpopulations secrete pro-tumorigenic cytokines and promote treatment resistance

Berg J, Halvorsen AR, Bengtson MB, et al.
Levels and prognostic impact of circulating markers of inflammation, endothelial activation and extracellular matrix remodelling in patients with lung cancer and chronic obstructive pulmonary disease.
BMC Cancer. 2018; 18(1):739 [PubMed] Article available free on PMC after 05/10/2019 Related Publications
BACKGROUND: The development of both chronic obstructive pulmonary disease (COPD) and lung cancer (LC) is influenced by smoking related chronic pulmonary inflammation caused by an excessive innate immune response to smoke exposure. In addition, the smoking induced formation of covalent bonds between the carcinogens and DNA and the accumulation of permanent somatic mutations in critical genes are important in the carcinogenic processes, and can also induce inflammatory responses. How chronic inflammation is mirrored by serum markers in COPD and LC and if these markers reflect prognosis in patients with LC is, however, largely unknown.
METHODS: Serum levels of 18 markers reflecting inflammation, endothelial activation and extracellular matrix remodelling were analysed in 207 patients with non-small lung carcinoma (NSCLC) before surgery and 42 COPD patients. 56% of the LC patients also suffered from COPD. The serum samples were analysed by enzyme immunoassays.
RESULTS: Serum levels of OPG, PTX3, AXL, ALCAM, sCD163, CD147, CatS and DLL1 were significantly higher in patients with COPD as compared to patients with LC. High sTNFR1 levels were associated with improved progression free survival (PFS) and overall survival (OS) in LC patients with (PFS hazard ratio (HR) 0.49, OS HR 0.33) and without COPD (OS HR 0.30). High levels of OPG were associated with improved PFS (HR 0.17) and OS (HR 0.14) for LC with COPD. CRP was significantly associated with overall survival regardless of COPD status.
CONCLUSION: Several markers reflecting inflammation, endothelial activation and extracellular matrix remodelling are elevated in serum from patients with COPD compared to LC patients. Presence of COPD might influence the levels of circulating biomarkers. Some of these markers are also associated with prognosis.

Kunz M, Löffler-Wirth H, Dannemann M, et al.
RNA-seq analysis identifies different transcriptomic types and developmental trajectories of primary melanomas.
Oncogene. 2018; 37(47):6136-6151 [PubMed] Related Publications
Recent studies revealed trajectories of mutational events in early melanomagenesis, but the accompanying changes in gene expression are far less understood. Therefore, we performed a comprehensive RNA-seq analysis of laser-microdissected melanocytic nevi (n = 23) and primary melanoma samples (n = 57) and characterized the molecular mechanisms of early melanoma development. Using self-organizing maps, unsupervised clustering, and analysis of pseudotime (PT) dynamics to identify evolutionary trajectories, we describe here two transcriptomic types of melanocytic nevi (N1 and N2) and primary melanomas (M1 and M2). N1/M1 lesions are characterized by pigmentation-type and MITF gene signatures, and a high prevalence of NRAS mutations in M1 melanomas. N2/M2 lesions are characterized by inflammatory-type and AXL gene signatures with an equal distribution of wild-type and mutated BRAF and low prevalence of NRAS mutations in M2 melanomas. Interestingly, N1 nevi and M1 melanomas and N2 nevi and M2 melanomas, respectively, cluster together, but there is no clustering in a stage-dependent manner. Transcriptional signatures of M1 melanomas harbor signatures of BRAF/MEK inhibitor resistance and M2 melanomas harbor signatures of anti-PD-1 antibody treatment resistance. Pseudotime dynamics of nevus and melanoma samples are suggestive for a switch-like immune-escape mechanism in melanoma development with downregulation of immune genes paralleled by an increasing expression of a cell cycle signature in late-stage melanomas. Taken together, the transcriptome analysis identifies gene signatures and mechanisms underlying development of melanoma in early and late stages with relevance for diagnostics and therapy.

Sun Y, Jiang F, Pan Y, et al.
XBP1 promotes tumor invasion and is associated with poor prognosis in oral squamous cell carcinoma.
Oncol Rep. 2018; 40(2):988-998 [PubMed] Related Publications
X‑box‑binding protein 1 (XBP1) contributes to various types of cancer including breast, bladder cancer and esophageal squamous cell carcinoma. The aim of the study was to examine the metastatic role of XBP1 in oral squamous cell carcinoma (OSCC), and identify possible downstream molecules. Immunohistochemical staining was conducted on tissue microarrays comprising 96 OSCC cases to determine the expression level of XBP1 and analyze its association with metastasis, clinicopathological characteristics and survival prognosis. Compared with the adjacent normal tissues of OSCC, the expression of XBP1 was significantly increased in the tumor center and front area, and lymph nodes metastases (P<0.05). A relatively high XBP1 expression was associated with histological grades (P<0.05), advanced clinical stages (P<0.05), unfavorable 5‑year survival (P=0.027). Suppressed XBP1 expression caused a significant reduction of cell invasion capability (P<0.05). AXL and the downstream molecules, such as PI3K, MMP1, MMP3, and uPA were significantly suppressed when XBP1 expression was inhibited in OSCC cells. Once XBP1 was activated by Thapsigargin, AXL expression was restored. Moreover, aberrant AXL expression was associated with XBP1 overexpression in OSCC tissues (P<0.05). In conclusion, XBP1 is a potential target that is relevant to suppressing cell invasion and is associated with patient prognosis in OSCC.

Antony J, Zanini E, Kelly Z, et al.
The tumour suppressor OPCML promotes AXL inactivation by the phosphatase PTPRG in ovarian cancer.
EMBO Rep. 2018; 19(8) [PubMed] Article available free on PMC after 05/10/2019 Related Publications
In ovarian cancer, the prometastatic RTK AXL promotes motility, invasion and poor prognosis. Here, we show that reduced survival caused by AXL overexpression can be mitigated by the expression of the GPI-anchored tumour suppressor OPCML Further, we demonstrate that AXL directly interacts with OPCML, preferentially so when AXL is activated by its ligand Gas6. As a consequence, AXL accumulates in cholesterol-rich lipid domains, where OPCML resides. Here, phospho-AXL is brought in proximity to the lipid domain-restricted phosphatase PTPRG, which de-phosphorylates the RTK/ligand complex. This prevents AXL-mediated transactivation of other RTKs (cMET and EGFR), thereby inhibiting sustained phospho-ERK signalling, induction of the EMT transcription factor Slug, cell migration and invasion. From a translational perspective, we show that OPCML enhances the effect of the phase II AXL inhibitor R428

Shabani N, Razaviyan J, Paryan M, et al.
Evaluation of miRNAs expression in medullary thyroid carcinoma tissue samples: miR-34a and miR-144 as promising overexpressed markers in MTC.
Hum Pathol. 2018; 79:212-221 [PubMed] Related Publications
Medullary thyroid carcinoma (MTC) is a rare neoplasia derived from neural parafollicular C cells. MicroRNAs (miRNAs) are small regulatory RNAs with essential roles in the biology of cancers such as MTC and can be applied as diagnostic markers. According to previous studies, miR-144 and miR-34 and their two oncogenes target, mammalian target of rapamycin (mTOR) and AXL receptor tyrosine kinase (AXL), were selected for further investigations in our study. Thirty MTC samples as well as thirty adjacent normal thyroid tissues were applied in this study including 28 formalin-fixed, paraffin-embedded (FFPE) and 2 fresh-frozen MTC samples. RNA extraction and complementary DNA (cDNA) synthesis were performed for all samples. After primer pairs and probes were designed, real-time polymerase chain reaction (real-time PCR) method was used, and the results were analyzed using 2

Guo Q, Grimmig T, Gonzalez G, et al.
ATP-binding cassette member B5 (ABCB5) promotes tumor cell invasiveness in human colorectal cancer.
J Biol Chem. 2018; 293(28):11166-11178 [PubMed] Article available free on PMC after 05/10/2019 Related Publications
ABC member B5 (ABCB5) mediates multidrug resistance (MDR) in diverse malignancies and confers clinically relevant 5-fluorouracil resistance to CD133-expressing cancer stem cells in human colorectal cancer (CRC). Because of its recently identified roles in normal stem cell maintenance, we hypothesized that ABCB5 might also serve MDR-independent functions in CRC. Here, in a prospective clinical study of 142 CRC patients, we found that ABCB5 mRNA transcripts previously reported not to be significantly expressed in healthy peripheral blood mononuclear cells are significantly enriched in patient peripheral blood specimens compared with non-CRC controls and correlate with CRC disease progression. In human-to-mouse CRC tumor xenotransplantation models that exhibited circulating tumor mRNA, we observed that cancer-specific ABCB5 knockdown significantly reduced detection of these transcripts, suggesting that the knockdown inhibited tumor invasiveness. Mechanistically, this effect was associated with inhibition of expression and downstream signaling of AXL receptor tyrosine kinase (AXL), a proinvasive molecule herein shown to be produced by ABCB5-positive CRC cells. Importantly, rescue of AXL expression in ABCB5-knockdown CRC tumor cells restored tumor-specific transcript detection in the peripheral blood of xenograft recipients, indicating that ABCB5 regulates CRC invasiveness, at least in part, by enhancing AXL signaling. Our results implicate ABCB5 as a critical determinant of CRC invasiveness and suggest that ABCB5 blockade might represent a strategy in CRC therapy, even independently of ABCB5's function as an MDR mediator.

Yu M, Li W, Wang Q, et al.
Circadian regulator NR1D2 regulates glioblastoma cell proliferation and motility.
Oncogene. 2018; 37(35):4838-4853 [PubMed] Related Publications
Nuclear receptor NR1D2 is originally characterized as the repressor of genes involved in circadian rhythm. Recently, it is documented that NR1D2 is overexpressed in various cancers. However, the pathways and biological functions that NR1D2 involved in cancers remain poorly understood. Here, we reported that NR1D2 was abundant in human glioblastoma (GBM) tissue and cell lines but not primary human astrocytes. Silencing of NR1D2 changed the morphology of GBM cells, inhibited cell proliferation and motility, whereas had no effects on apoptosis. Importantly, based on RNA-seq and ChIP assay, we identified receptor tyrosine kinase AXL as a new transcriptional target of NR1D2 in GBM cells. AXL mediated partially the regulatory effects of NR1D2 on PI3K/AKT axis and promoted proliferation, migration, and invasion of GBM cells. Besides, NR1D2 knockdown remarkably impaired the maturation of focal adhesion and assembly of F-actin, along with downregulated p-FAK, and proteins involved in actin nucleation and polymerization (p-Rac1/Cdc42, WAVE and PFN2). Moreover, NR1D2 had more targets other than AXL to regulate epithelial-to-mesenchymal transition and cell motility in GBM cells. Altogether, our findings uncover a GBM-promoting role of NR1D2 and provide the rationale for targeting NR1D2 as a potential therapeutic approach.

Alam H, Li N, Dhar SS, et al.
HP1γ Promotes Lung Adenocarcinoma by Downregulating the Transcription-Repressive Regulators NCOR2 and ZBTB7A.
Cancer Res. 2018; 78(14):3834-3848 [PubMed] Article available free on PMC after 05/10/2019 Related Publications
Lung adenocarcinoma is a major form of lung cancer, which is the leading cause of cancer death. Histone methylation reader proteins mediate the effect of histone methylation, a hallmark of epigenetic and transcriptional regulation of gene expression. However, their roles in lung adenocarcinoma are poorly understood. Here, our bioinformatic screening and analysis in search of a lung adenocarcinoma-promoting histone methylation reader protein show that heterochromatin protein 1γ (HP1γ; also called CBX3) is among the most frequently overexpressed and amplified histone reader proteins in human lung adenocarcinoma, and that high

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