Expression Of Lyn Kinase Research Articles

MiR-496 inhibits proliferation via LYN and AKT pathway in gastric cancer.

MicroRNAs (miRNAs) operate as tumor suppressor or carcinogen to regulate cell proliferation, metastasis, invasion, differentiation, apoptosis, and metabolic process. In the present research, we investigated the effect and mechanism of miR-496 in human gastric cancer cells. miR-496 was downregulated in two gastric cancer cell lines, AGS and MKN45, compared with normal gastric epithelial cell line GES-1. miR-496 mimics inhibited the proliferation of AGS cells after the transfection for 48 and 72 h. The migration and invasion of AGS cells were also inhibited by the transfection of miR-496 mimics. miR-496 mimics induced the apoptosis through upregulating the levels of Bax and Active Caspase 3 and downregulating the levels of Bcl-2 and Total Caspase 3. Bioinformatics analysis showed that there was a binding site between miR-496 and Lyn kinase (LYN). miR-496 mimics could inhibit the expression of LYN in AGS cells. LYN overexpression blocked the inhibition of tumor cell growth, as well as the inhibition of AKT/mTOR signaling pathway induced by miR-496. In conclusion, miR-496 inhibited the proliferation through the AKT/mTOR signaling pathway via targeting LYN in gastric cancer cells. Our research provides a new potential target for clinical diagnosis and targeted treatment for gastric cancer.

Signaling via Src Family Kinases Is Required for Normal Internalization of the Receptor c-Kit

AbstractStem cell factor (SCF) exerts its biological effects by binding to a specific receptor, the tyrosine kinase c-Kit, which is expressed on the cell surface. Although normal cellular trafficking of growth factor receptors may play a critical role in the modulation of receptor function, the mechanisms that regulate the distribution of c-Kit on the cell surface and the internalization of c-Kit have not been fully defined. We investigated whether signal transduction via Src family kinases is required for normal c-Kit trafficking. Treatment of the SCF-responsive human hematopoietic cell line MO7e with the inhibitor of Src family kinases PP1 blocked SCF-induced capping of c-Kit and internalization of c-Kit. c-Kit was able to associate with clathrin in the presence of PP1, suggesting that entry of c-Kit into clathrin-coated pits occurs independently of Src family kinases. SCF-induced internalization of c-Kit was also diminished in the D33-3 lymphoid cell line in which expression of Lyn kinase was disrupted by homologous recombination. These results indicate that Src family kinases play a role in ligand-induced trafficking of c-Kit.

Lyn Kinase Promotes the Proliferation of Malignant Melanoma Cells through Inhibition of Apoptosis and Autophagy via the PI3K/Akt Signaling Pathway.

Melanoma is a malignant tumor of cutaneous melanocytes that is characterized by high grade malignancy, rapid progression and high mortality. Thus far, its specific etiological mechanism has been unclear. In this study, we discovered that Lyn kinase expression was up-regulated in melanoma tissues and cells. The function of Lyn was determined by knocking down its expression with a lentivirus containing Lyn shRNA and upregulating its expression with pcDNA3.1-Lyn in the melanoma cell lines M14 and A375. The results showed that Lyn knockdown could significantly inhibit the proliferation, migration and invasiveness through its inhibition of apoptosis and autophagy via the PI3K/Akt pathway in melanoma cell lines. This was further confirmed by treatment with PI3K inhibitor BEZ235. Up-regulation of Lyn promoted the expression of p-Akt and Cyclin D1. Additionally, we investigated the effects of Lyn inhibitor Bafetinib on melanoma cells and the results were consistent with Lyn knockdown. Collectively, our results indicated that Lyn plays a carcinogenic role in multiple cellular functions during melanoma development through regulating apoptosis and autophagy via the PI3K/Akt pathway and may be a valuable potential target for the clinical treatment of melanoma.

Abstract 1682: Lyn drives cancer metastasis via post-translational regulation of SNAI proteins

Abstract Introduction: Metastasis is the most common cause of death from cancer and occurs when malignant cells discard epithelial restraints and acquire invasive abilities, facilitating their dissemination to permissive micro-environments. This process is enhanced by tumor cell activation of Epithelial Mesenchymal Transition (EMT), a (normally embryonic) developmental program in which epithelial cells assume a mesenchymal phenotype during gastrulation and organogenesis, allowing single cell invasive movement away from the ectodermal layer. Recent evidence strongly implicates EMT induction in malignant progression and treatment resistance. For example, EMT regulatory transcription factors are required for breast cancer metastasis. Several oncogenic pathways (growth factors, Src family, MAPK, AKT) induce EMT. Lyn tyrosine kinase, a member of Src family tyrosine kinase is up-regulated in advanced prostate cancer and has been reported to correlate with aggressive breast cancer. Our objective is to determine the role of Lyn tyrosine kinase in EMT. Methods: LNCaP (Lymph Node Metastasis of Prostate Cancer), BT-549 (Triple Negative Breast Cancer) and UM-UC-13 (Bladder Cancer) cells were transfected with Lyn siRNA; EMT markers were monitored by western blot and qRT-PCR and immunofluorescence, migration by scratch assay and invasion by Boyden chamber. Sub cellular localization of proteins was examined by IF and nuclear/cyto extraction. In vivo experiments were performed in UC13-luc cells with shRNA of Lyn. Results: Here we report that Lyn expression is low in epithelial cells and is up-regulated in mesenchymal cells. Targeting Lyn using siRNA decreases EMT markers (Fibronectin, Vimentin and Zeb-1) at both mRNA and protein levels while increasing the epithelial marker (E-cadherin). Moreover, we found that Lyn siRNA decreases cell migration and invasion. Thisis decrease in mesenchymal phenotype can be attributed to the decrease in the amount of Slug and Snail, transcriptional repressors of E-Cadherin and activator of Vimentin and Fibronectin. Interestingly, we found that Lyn knockout induces a decrease of SLUG only at protein levels and not at mRNA levels. We discovered that Lyn triggers a signaling cascade through Vav-Rac-Pak1 pathway to alter sub cellular localization of the SNAI proteins leading to their proteasomal degradation. This effect results in decreased invasion and migration in vitro as well as decreased metastasis in vivo. Conclusion: Expression of Lyn kinase can be correlated to low prognosis and aggressive/metastatic phenotype. We show that knocking down Lyn by siRNA initiates a switch to a more epithelial phenotype reducing cell migration and invasion. Citation Format: Daksh Thaper, Sepideh Vahid, Ka Mun Nip, Igor Moskalev, Sebastian Frees, Morgan E. Roberts, Krisi Ketola, Kenneth W. Harder, Jennifer L. Bishop, Amina Zoubeidi. Lyn drives cancer metastasis via post-translational regulation of SNAI proteins. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1682.

Abstract 4106: Lyn kinase promotes metastasis through EMT in cancers

Abstract Introduction: Metastasis is the most common cause of death from cancer and occurs when malignant cells discard epithelial restraints and acquire invasive abilities, facilitating their dissemination to permissive micro-environments. This process is enhanced by tumor cell activation of Epithelial Mesenchymal Transition (EMT), a (normally embryonic) developmental program in which epithelial cells assume a mesenchymal phenotype during gastrulation and organogenesis, allowing single cell invasive movement away from the ectodermal layer. Recent evidence strongly implicates EMT induction in malignant progression and treatment resistance. For example, EMT regulatory transcription factors are required for breast cancer metastasis. Several oncogenic pathways (growth factors, Src family, MAPK, AKT) induce EMT. Lyn tyrosine kinase, a member of Src family tyrosine kinase is up-regulated in advanced prostate cancer and has been reported to correlate with aggressive breast cancer. Our objective is to determine the role of Lyn tyrosine kinase in EMT. Methods: LNCaP, BT-549, UC-13 cells were transfected with Lyn siRNA; EMT markers were monitored by western blot and qRT-PCR and immunofluorescence, migration by scratch assay, invasion by Boyden chamber and matrix metalloproteinase (MMP) activity by Zymography. Lyn specific Kinase inhibitor Bafetinib will also be used along with over-expression experiments with Lyn Kinase Dead and Constitutively active mutants. Results: Here we report that Lyn expression is low in epithelial cells and is up-regulated in mesenchymal cells. Targeting Lyn using siRNA decreases EMT markers (Fibronectin, Vimentin) at both mRNA and protein levels while increasing the epithelial marker (E-cadherin). Moreover, we found that targeting Lyn by siRNA/shRNA and small molecule inhibitor Bafetinib decreases cell migration, invasion and the activity of MMPs. This decrease in mesenchymal phenotype can be attributed to the decrease in the amount of Slug and Snail, transcriptional repressors of E-Cadherin and activators of Vimentin. Consequently, we also found that over-expressing Lyn in both as WT or constitutively active (CA) mutant rescues expression of Slug and Snail, inducing EMT, increased cell migration and invasion while Kinase Dead (KD) mutant has no effect. Conclusion: Expression of Lyn kinase can be correlated to low prognosis and aggressive/metastatic phenotype. We show that targeting Lyn activity initiates a switch to a more epithelial phenotype reducing cell migration and invasion. Impact: The data suggests that Lyn tyrosine kinase plays a role in Epithelial Mesenchymal Transition and could be considered as a target for metastatic disease; especially in the more aggressive forms of cancer like Triple Negative Breast Cancer or Castration Resistant Prostate Cancer. This could be a realistic therapeutic option, as the Lyn small molecule inhibitor Bafetinib, is currently in clinical trials for treatment of several cancers. Note: This abstract was not presented at the meeting. Citation Format: Daksh Thaper, Sepideh Vahid, Ka Mun Nip, Kirsi Ketola, Jennifer Bishop, Amina Zoubeidi. Lyn kinase promotes metastasis through EMT in cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4106. doi:10.1158/1538-7445.AM2015-4106

CBL Linker Region and RING Finger Mutations Lead to Enhanced Granulocyte-Macrophage Colony-stimulating Factor (GM-CSF) Signaling via Elevated Levels of JAK2 and LYN

Juvenile myelomonocytic leukemia (JMML) is characterized by hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF). SHP2, NF-1, KRAS, and NRAS are mutated in JMML patients, leading to aberrant regulation of RAS signaling. A subset of JMML patients harbor CBL mutations associated with 11q acquired uniparental disomy. Many of these mutations are in the linker region and the RING finger of CBL, leading to a loss of E3 ligase activity. We investigated the mechanism by which CBL-Y371H, a linker region mutant, and CBL-C384R, a RING finger mutant, lead to enhanced GM-CSF signaling. Expression of CBL mutants in the TF-1 cell line resulted in enhanced survival in the absence of GM-CSF. Cells expressing CBL mutations displayed increased phosphorylation of GM-CSF receptor βc subunit in response to stimulation, although expression of total GM-CSFR βc was lower. This suggested enhanced kinase activity downstream of GM-CSFR. JAK2 and LYN kinase expression is elevated in CBL-Y371H and CBL-C384R mutant cells, resulting in enhanced phosphorylation of CBL and S6 in response to GM-CSF stimulation. Incubation with the JAK2 inhibitor, TG101348, abolished the increased phosphorylation of GM-CSFR βc in cells expressing CBL mutants, whereas treatment with the SRC kinase inhibitor dasatinib resulted in equalization of GM-CSFR βc phosphorylation signal between wild type CBL and CBL mutant samples. Dasatinib treatment inhibited the elevated phosphorylation of CBL-Y371H and CBL-C384R mutants. Our study indicates that CBL linker and RING finger mutants lead to enhanced GM-CSF signaling due to elevated kinase expression, which can be blocked using small molecule inhibitors targeting specific downstream pathways.

CHK negatively regulates Lyn kinase and suppresses pancreatic cancer cell invasion

Among the most important signaling pathways operating in pancreatic cancer cells are those resulting from mutations in the Ras oncogene or from overexpression of ErbB-2 and associated Src-family kinases. In this study, we aimed to characterize CHK expression and function in pancreatic cancer. Our data demonstrated CHK expression in human pancreatic cancer tissues, and also showed that CHK associated with ErbB-2 via its SH2 domain in human PANC-1 pancreatic cancer cells. PANC-1 cells were found to express both Src kinase and Lyn kinase, although the expression of Lyn kinase was more abundant. Furthermore, CHK downregulated Lyn kinase activity and significantly inhibited the in vitro growth and invasion of PANC-1 cells upon EGF stimulation. These results indicate that CHK is a negative regulator of ErbB-2 and Lyn kinase signaling in pancreatic cancer cells.