The Akt-mTORC1 pathway mediates Axl receptor tyrosine kinase-induced mesangial cell proliferation.
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ABSTRACT:
SUBMITTER: Zhen Y
PROVIDER: S-EPMC9328168 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The epidermal growth factor receptor (EGFR) is a therapeutic target in patients with various cancers. Unfortunately, resistance to EGFR-targeted therapeutics is common. Previous studies identified two mechanisms of resistance to the EGFR monoclonal antibody cetuximab. Nuclear translocation of EGFR bypasses the inhibitory effects of cetuximab, and the receptor tyrosine kinase AXL mediates cetuximab resistance by maintaining EGFR activation and downstream signaling. Thus, we hypothesized that AXL mediated the nuclear translocation of EGFR in the setting of cetuximab resistance. Cetuximab-resistant clones of non-small cell lung cancer in culture and patient-derived xenografts in mice had increased abundance of AXL and nuclear EGFR (nEGFR). Cellular fractionation analysis, super-resolution microscopy, and electron microscopy revealed that genetic loss of AXL reduced the accumulation of nEGFR. SRC family kinases (SFKs) and HER family ligands promote the nuclear translocation of EGFR. We found that AXL knockdown reduced the expression of the genes encoding the SFK family members YES and LYN and the ligand neuregulin-1 (NRG1). AXL knockdown also decreased the interaction between EGFR and the related receptor HER3 and accumulation of HER3 in the nucleus. Overexpression of LYN and NRG1 in cells depleted of AXL resulted in accumulation of nEGFR, rescuing the deficit induced by lack of AXL. Collectively, these data uncover a previously unrecognized role for AXL in regulating the nuclear translocation of EGFR and suggest that AXL-mediated SFK and NRG1 expression promote this process.
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Project description:AimsTriple-negative breast cancer comprises a clinically aggressive group of invasive carcinomas. We examined a published gene expression screen of a panel of breast cancer cell lines to identify a potential triple-negative breast cancer-specific gene signature, and attempted to verify our findings by performing immunohistochemical analysis on tissue microarrays containing a large cohort of invasive breast carcinomas.MethodsThe microarray dataset for a panel of human breast cancer cell lines was interrogated for triple-negative breast cancer-specific genes. Membranous immunohistochemical expression of the protein product of the AXL gene was assessed semiquantitatively in 569 invasive breast carcinomas grouped according to molecular subgroup by immunohistochemistry.ResultsAXL was significantly upregulated in triple-negative/basal B cell lines compared with luminal or basal A cell lines. No significant difference was observed in the level of immunohistochemical expression of Axl protein between triple-negative breast cancers and other molecular subgroups (p=0.257). Axl expression was significantly associated with lymphovascular invasion (LVI) in all subgroups combined (p=0.033), and within the luminal A (p=0.002) and triple-negative breast cancer subgroups (p=0.026).ConclusionsDespite preferential upregulation of AXL in triple-negative/basal B cell lines, analysis of Axl protein expression in a large series of patients' breast tumours revealed no association between Axl expression and triple-negative breast cancer or other subtype. The association of Axl expression with LVI supports previous work that implicates Axl as a promoter of invasiveness in breast cancer cell lines. Further studies are necessary to explore whether Axl expression of individual breast cancer tumours can be clinically useful.
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Project description:Overexpression and amplification of AXL receptor tyrosine kinase (RTK) has been found in several hematologic and solid malignancies. Activation of AXL can enhance tumor-promoting processes such as cancer cell proliferation, migration, invasion and survival. Despite the important role of AXL in cancer development, a deep and quantitative mapping of its temporal dynamic signaling transduction has not yet been reported. Here, we used a TMT labeling-based quantitative proteomics approach to characterize the temporal dynamics of the phosphotyrosine proteome induced by AXL activation. We identified >1100 phosphotyrosine sites and observed a widespread upregulation of tyrosine phosphorylation induced by GAS6 stimulation. We also detected several tyrosine sites whose phosphorylation levels were reduced upon AXL activation. Gene set enrichment-based pathway analysis indicated the activation of several cancer-promoting and cell migration/invasion-related signaling pathways, including RAS, EGFR, focal adhesion, VEGFR and cytoskeletal rearrangement pathways. We also observed a rapid induction of phosphorylation of protein tyrosine phosphatases, including PTPN11 and PTPRA, upon GAS6 stimulation. The novel molecules downstream of AXL identified in this study along with the detailed global quantitative map elucidating the temporal dynamics of AXL activation should not only help understand the oncogenic role of AXL, but also aid in developing therapeutic options to effectively target AXL.
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Project description:BackgroundReceptor tyrosine kinase AXL has been found to be highly expressed in osteosarcoma and positively associated with poor prognosis. There are tumor groups with high or low AXL expression, which had different capabilities of invading vessels and forming distal metastases. Exosome-transmitted lncRNA may be transferred intercellularly to promote tumor cells' proliferation and invasion.MethodsExosomes were detected by electron microscopy, particle size analysis, and western blotting. High-throughput sequencing helped to find the highest differentially expressed lncRNA in AXL-associated exosomes. Clone formation, wound healing, transwell assay, and xenograft model in nude mice were performed to evaluate cells' proliferation, migration, and invasion in vitro and in vivo. Lentiviral transfection was used to up- or down-regulate the lncRNA levels in cell lines. Luciferase reporter assay and RNA FISH etchelped to indicate the molecular mechanisms. The results in the cell lines were proved in the osteosarcoma tissues with clinical analysis.ResultsThe exosomes derived from donor cells with high AXL expression could promote the proliferation and invasion and upregulate AXL expression of the receiver cells with low AXL. Linc00852 was the highest differentially expressed lncRNA in AXL-associated exosomes and was also regulated by AXL expression. Although the mechanisms of linc00852 in nucleus were unrevealed, it could upregulate AXL expression partly by competitively binding to miR-7-5p. The AXL-exosome-linc00852-AXL positive feedback loop might exist between the donor cells and the receiver cells. Clinically, linc00852 was significantly highly expressed in osteosarcoma tissues and positively associated with tumor volumes and metastases, which was also obviously related with AXL mRNA expression.ConclusionAXL-associated exosomal linc00852 up-regulated the proliferation, migration, and invasion of osteosarcoma cells, which would be considered as a new tumor biomarker and a special therapeutic target for osteosarcoma.
| S-EPMC7476833 | biostudies-literature
Project description:IntroductionHepatocellular carcinoma (HCC) patients at advanced stages receive immunotherapy or treatment with tyrosine kinase inhibitors (TKIs) such as Sorafenib (Sora) or Lenvatinib in frontline as well as Regorafenib (Rego) or Cabozantinib in second-line. A major hindrance of TKI therapies is the development of resistance, which renders drug treatment futile and results in HCC progression.MethodsIn this study, we addressed the impact of the receptor tyrosine kinase Axl binding to its ligand Gas6 in acquiring refractoriness to TKIs. The initial responses of Axl-positive and Axl-negative cell lines to different TKIs were assessed. Upon inducing resistance, RNA-Seq, gain- and loss-of-function studies were applied to understand and intervene with the molecular basis of refractoriness. Secretome analysis was performed to identify potential biomarkers of resistance.ResultsWe show that HCC cells exhibiting a mesenchymal-like phenotype were less sensitive to drug treatment, linking TKI resistance to changes in epithelial plasticity. Gas6/Axl expression and activation were upregulated in Rego-resistant HCC cells together with the induction of ErbB receptors, whereas HCC cells lacking Axl failed to stimulate ErbBs. Treatment of Rego-insensitive HCC cells with the pan-ErbB family inhibitor Afatinib rather than with Erlotinib blocking ErbB1 reduced cell viability and clonogenicity. Genetic intervention with ErbB2-4 but not ErbB1 confirmed their crucial involvement in refractoriness to Rego. Furthermore, Rego-resistant HCC cells secreted basic fibroblast growth factor (bFGF) depending on Axl expression. HCC patients treated with Sora in first-line and with Rego in second-line displayed elevated serum levels of bFGF, emphasizing bFGF as a predictive biomarker of TKI treatment.DiscussionTogether, these data suggest that the inhibition of ErbBs is synthetic lethal with Rego in Axl-expressing HCC cells, showing a novel vulnerability of HCC.
| S-EPMC10514905 | biostudies-literature
Project description:BackgroundSome recent studies on insulin receptor tyrosine kinase substrate (IRTKS) have focused more on its functions in diseases. However, there is a lack of research on the role of IRTKS in carcinomas and its mechanism remains ambiguous. In this study, we aimed to clarify the role and mechanism of IRTKS in the carcinogenesis of colorectal cancer (CRC).MethodsWe analysed the expression of IRTKS in CRC tissues and normal tissues by researching public databases. Cancer tissues and adjacent tissues of 67 CRC patients who had undergone radical resection were collected from our center. Quantitative real-time polymerase chain reaction and immunohistochemistry were performed in 52 and 15 pairs of samples, respectively. In vitro and in vivo experiments were conducted to observe the effect of IRTKS on CRC cells. Gene Set Enrichment Analysis and Metascape platforms were used for functional annotation and enrichment analysis. We detected the protein kinase B (AKT) phosphorylation and cell viability of SW480 transfected with small interfering RNAs (siRNAs) with or without basic fibroblast growth factor (bFGF) through immunoblotting and proliferation assays.ResultsThe expression of IRTKS in CRC tissues was higher than that in adjacent tissues and normal tissues (all P < 0.05). Disease-free survival of patients with high expression was shorter. Overexpression of IRTKS significantly increased the proliferation rate of CRC cells in vitro and the number of tumor xenografts in vivo. The phosphorylation level of AKT in CRC cells transfected with pLVX-IRTKS was higher than that in the control group. Furthermore, siRNA-IRTKS significantly decreased the proliferation rate of tumor cells and the phosphorylation level of AKT induced by bFGF.ConclusionIRTKS mediated the bFGF-induced cell proliferation through the phosphorylation of AKT in CRC cells, which may contribute to tumorigenicity in vivo.
| S-EPMC8128016 | biostudies-literature
Project description:Owing to its clinical significance, modulation of functionally relevant amino acids in protein-protein complexes has attracted a great deal of attention. To this end, many approaches have been proposed to predict the partner-selecting amino acid positions in evolutionarily close complexes. These approaches can be grouped into sequence-based machine learning and structure-based energy-driven methods. In this work, we assessed these methods' ability to map the specificity-determining positions of Axl, a receptor tyrosine kinase involved in cancer progression and immune system diseases. For sequence-based predictions, we used SDPpred, Multi-RELIEF, and Sequence Harmony. For structure-based predictions, we utilized HADDOCK refinement and molecular dynamics simulations. As a result, we observed that (i) sequence-based methods overpredict partner-selecting residues of Axl and that (ii) combining Multi-RELIEF with HADDOCK-based predictions provides the key Axl residues, covered by the extensive molecular dynamics simulations. Expanding on these results, we propose that a sequence-structure-based approach is necessary to determine specificity-determining positions of Axl, which can guide the development of therapeutic molecules to combat Axl misregulation.
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Project description:The AXL receptor tyrosine kinase and its ligand, Gas6, regulate key processes in lung cancer growth, metastasis, and epithelial-mesenchymal transition-associated drug resistance. Gas6 and AXL expression have been correlated with poor prognosis and advanced clinical stage in patients with lung cancer, and targeting the Gas6/AXL pathway demonstrates antitumor activity, decreases cellular invasion, and restores sensitivity in de novo and acquired drug resistance models. These findings implicate AXL as a promising therapeutic target in lung cancer. In this review, we explore the role of AXL in lung cancer progression, from tumor development to disseminated disease, and highlight the current clinical landscape of anti-AXL therapeutics.
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Project description:Monocytes and macrophages (m) are plastic cells whose functions are governed by microenvironmental cues. Wound fluid bathing the wound tissue reflects the wound microenvironment. Current literature on wound inflammation is primarily based on the study of blood monocyte-derived macrophages, cells that have never been exposed to the wound microenvironment. We sought to compare pair-matched monocyte-derived macrophages with m isolated from chronic wounds of patients. Oncostatin M (OSM) was differentially overexpressed in pair-matched wound m. Both PGE? and its metabolite 13,14-dihydro-15-keto-PGE? (PGE-M) were abundant in wound fluid and induced OSM in wound-site m. Consistently, induction of OSM mRNA was observed in m isolated from PGE?-enriched polyvinyl alcohol sponges implanted in murine wounds. Treatment of human THP-1 cell-derived m with PGE? or PGE-M caused dose-dependent induction of OSM. Characterization of the signal transduction pathways demonstrated the involvement of EP4 receptor and cAMP signaling. In human m, PGE? phosphorylated Axl, a receptor tyrosine kinase (RTK). Axl phosphorylation was also induced by a cAMP analogue demonstrating interplay between the cAMP and RTK pathways. PGE?-dependent Axl phosphorylation led to AP-1 transactivation, which is directly implicated in inducible expression of OSM. Treatment of human m or mice excisional wounds with recombinant OSM resulted in an anti-inflammatory response as manifested by attenuated expression of endotoxin-induced TNF-? and IL-1?. OSM treatment also improved wound closure during the early inflammatory phase of healing. In summary, this work recognizes PGE? in the wound fluid as a potent inducer of m OSM, a cytokine with an anti-inflammatory role in cutaneous wound healing.
| S-EPMC3438225 | biostudies-literature
Project description:Background:Gastric cancer (GC) is an aggressive malignancy with high lethality. Systematic chemotherapy is the main therapeutic strategy for advanced GC patients. The overexpression of Axl is associated with poor prognosis and regulates tumor growth and metastasis in many types of cancer. However, the role of Axl in GC progression remains elusive. Materials and Methods:Western blot and quantitative real-time PCR assay (RT-PCR) assays were used to detect the expression of Gas6, Axl, ZEB1 and epithelial-mesenchymal transition (EMT)-related markers in GC cells. Cell proliferation was determined by EdU cell proliferation assay and CCK-8 assay. Transwell invasion assay was performed to explore the effect of Axl and ZEB1 on cell invasion. Tumor xenografts and lung metastasis models were conducted to examine the effect of Axl on the growth and lung metastasis of GC cells. Results:In our study, we found that high levels of Gas6 and Axl expression were associated with reduced overall survival (OS) in GC patients and the expression of Gas6 and Axl was upregulated in GC cell lines. Ectopic expression of Axl induced EMT and promoted GC cell invasion and proliferation. The knockdown of Axl inhibited EMT and suppressed the proliferation and invasion of GC cell. In vivo study showed that inhibition of Axl impaired tumor growth and lung metastasis of GC cells. Mechanistic investigations revealed that Axl promoted EMT, invasion, and proliferation via upregulating ZEB1 expression in GC cells. Conclusion:Our results demonstrated that the Gas6/Axl/ZEB1 signaling pathway regulated EMT, invasion, and proliferation in GC cells and might represent a potential therapeutic target for GC treatment.
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