Src Expression Research Articles

MicroRNA-144-3p suppressed TGF-β1-induced lung cancer cell invasion and adhesion by regulating the Src-Akt-Erk pathway.

Lung cancer remains a leading cause to cancer-related death worldwide. The anti-cancer ability of microRNA-144-3p has been reported in many cancer types. This study focused on the mechanisms underlying miR-144-3p in inhibiting lung cancer. The expression levels of miR-144-3p and steroid receptor coactivator (Src) in different lung cancer cell lines and those in bronchial epithelial cells (16HBE) were compared. miR-144-3p mimic and siSrc were transfected into A549 cells. Under the conditions of transforming growth factor-β1 (TGF-β1). Small interfering transfection or TGF-β1 treatment, cell invasive and adhesive abilities were analyzed by Transwell and cell adhesion assays. miR-144-3p inhibitor and siSrc were co-transfected into A549 cells and the changes in cell invasion and adhesion were detected. The activation of Src-protein kinase B-extracellular-regulated protein kinases (Src-Akt-Erk) pathway was determined using Western blot. The downregulated miR-144-3p and upregulated Src were generally detected in lung cancer cell lines and were the most significant genes in A549 cells. Both miR-144-3p overexpression and Src inhibition could obviously inhibit the invasion and adhesion abilities of A549 cells in the presence or absence of the effects of TGF-β1. The inhibition of Src could block the promotive effects of miR-144-3p inhibitor and TGF-β1 on cell invasion and adhesion. Furthermore, we found that miR-144-3p could negatively regulate the phosphorylation levels of Akt and Erk. Our data indicated the essential role of Src in the mechanisms underlying TGF-β1-induced cell invasion and adhesion of lung cancer, and that miR-144-3p could effectively suppress TGF-β1-induced aggressive lung cancer cells by regulatingSrc expression.

Cisplatin resistant lung cancer cells promoted M2 polarization of tumor-associated macrophages via the Src/CD155/MIF functional pathway

BackgroundLung cancer often ranks one of the most prevalent malignancies in the world. One of the most challenging aspects of treating late-stage lung cancer patients is the development of drug resistance, from both conventional chemo- and targeted therapeutic agents. Tumor-associated microphages (TAMs) have been shown to promote the survival and distant metastasis of lung cancer cells.MethodsThis study investigated the TAMs - modulating potential of cisplatin-resistant non-small cell lung cancer (NSCLC) cell lines, A549R and H460R by using bioinformatics approach, immunoblotting, immunofluorescence staining, migration, invasion, colony, lung sphere formation and xenograft tumorigenecity assays.ResultsIn this study, we first demonstrated the elevated expression of oncogenic and stemenss markers such as Src, Notch1, macrophage inhibitory factor (MIF) and CD155 in trained cisplatin (CDDP)-resistant A549 and H460 cells (A549R and H460R cells). When co-cultured with TAMs, A549R and H460R cells promoted the M2-polarization in TAMs. In addition, A549R and H460R cells showed an increased self-renewal ability as they formed tumor spheres at higher frequency comparing to their parental counterparts. The increased MIF secretion by the A549R and H460R cells could be suppressed by a multiple kinase inhibitor, dasatinib, which resulted in the decreased of oncogenic network of Src, CD155 and MIF expression. Similarly, dasatinib treatment reduced the M2 polarization in TAMs and suppressed self-renewal ability of the A549R and H460R cells.ConclusionIn summary, cisplatin resistant lung cancer cells not only showed an increased self-renewal ability but also promoted M2 polarization of TAMs via the secretion of MIF. These findings were linked to the increased Src-associated signaling as dasatinib treatment significantly reversed these phenomena. Thus, kinase inhibitors such as dasatinib may be of potential for treating cisplatin-resistant lung cancer by targeting both tumor and the tumor microenvironment.Graphical abstract

Blockade of HMGB1 signaling pathway by ethyl pyruvate inhibits tumor growth in diffuse large B-cell lymphoma

High mobility group box 1 (HMGB1) protein in the tumor microenvironment actively contributes to tumor progression but its role in diffuse large B-cell lymphoma (DLBCL) is unknown. The aim of this study was to determine the mechanism by which HMGB1 promotes tumor growth in DLBCL and whether blockade of HMGB1 signaling pathway could inhibit tumorigenesis. We report that HMGB1 promotes proliferation of DLBCL cells by activation of AKT, extracellular signal-regulated kinases 1/2 (ERK1/2), signal transducer and activator of transcription 3 (STAT3) and SRC Proto-Oncogene, Non-Receptor Tyrosine Kinase (Src). Ethyl pyruvate (EP), an anti-inflammatory agent, inhibits HMGB1 active release from DLBCL cells and significantly inhibited proliferation of DLBCL cells in vitro. Treatment with EP significantly prevented and inhibited tumor growth in vivo and prolonged DLBCL-bearing mice survival. EP significantly downregulated HMGB1 expression and phosphorylation of Src and ERK1/2 in mice lymphoma tissue. EP induced accumulation of the cell cycle inhibitor p27 but downregulated expression of cyclin-dependent kinase 2 (CDK2). Increased nuclear translocation of p27 interacted with CDK2 and cyclin A, which led to blockade of cell cycle progression at the G1 to S phase transition. In conclusion, we demonstrated for the first time that blockade of HMGB1-mediated signaling pathway by EP effectively inhibited DLBCL tumorigenesis and disease progression.

Antimetastatic potential of Atovaquone against triple negative breast cancer: Involvement of the integrin‐FAK‐Src pathway

Triple negative breast cancer (TNBC) is considered to be the most aggressive and malignant neoplasm and is highly metastatic in nature. Metastatic TNBC is difficult to treat and thus leads to poor patient survival. Death of about 90% breast cancer patients is due to metastasis of primary tumor to distant sites. In the current study, we investigated the anti‐metastatic potential of atovaquone, a protozoal drug prescribed for Pneumocystis pneumonia. We show that atovaquone induced apoptosis and reduced the survival of several aggressive metastatic TNBC cell lines including few metastatic patient derived cells. The IC50 of atovaquone was around 11–18 μM in the breast cancer cell lines tested. Additionally, atovaquone treatment significantly reduced the expression of integrinα6, integrin β4, FAK, Src, and Vimentin in MDA‐MB‐231, HCC1806 and 4T1 cells after 72 hours of treatment. In order to study the efficacy of atovaquone in preventing metastasis of breast tumor cells to brain and lungs, we performed three in vivo experiments. We demonstrate that oral administration of 50mg/kg of atovaquone suppressed MDA‐MB‐231 breast tumor growth by 90% in lungs in an intravenous metastatic tumor model. Further anti metastatic effect of atovaquone was determined by intracardiac injection of 4T1‐luc breast tumor cells into the left ventricle of mouse heart. Once breast cancer cells lodged in the brain, mice were treated with 50 mg/kg atovaquone for 15 days. Our results show that atovaquone treatment suppressed the growth of metastatic tumors in brain by 30%. In this model, we also observed 70% and 50% reduced metastasis of breast tumors in lungs and liver, respectively, in atovaquone treated group when compared with control. In intracranial model, the growth of HCC1806‐luc brain tumors in atovaquone treated mice was about 55% less than that of control. Angiogenesis is one of the hallmarks of cancer and plays crucial role in metastasis. Interestingly, we observed reduced levels of VEGF in the cells treated with atovaquone. In‐vivo angiogenesis was evaluated by performing matrigel plug assay in mice. Our results showed reduced angiogenesis in atovaquone treated mice group. Atovaquone treated tumors from these in‐vivo models exhibited reduced metastatic markers and increased apoptosis. Taken together, our results indicate the anti‐metastatic effects of atovaquone in‐vitro and in‐vivo in various breast tumor metastasis models by inhibiting angiogenesis and integrin signaling and provides the rationale for further clinical investigation of atovaquone for breast cancer metastasis.Support or Funding InformationThis work is supported in part by RO1 grant CA129038, awarded by National Cancer Institute, (NIH) to Sanjay K. Srivastava.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Prognostic Impact of Src, CDKN1B, and JAK2 Expression in Metastatic Breast Cancer Patients Treated with Trastuzumab

BACKGROUND: Src, CDKN1B, and JAK2 play a crucial role in the coordination of cell signaling pathways. In the present study, we aim to investigate the prognostic significance of these biomarkers in HER2-positive metastatic breast cancer (MBC) patients treated with trastuzumab (T). METHODS: Formalin-fixed paraffin-embedded tumor tissue samples from 197 patients with HER2-positive MBC treated with T were retrospectively collected. All tissue samples were centrally assessed for ER, PgR, Ki67, HER2, and PTEN protein expression; EGFR gene amplification; PI3KCA mutational status; and tumor-infiltrating lympocytes density. Src, CDKN1B, and JAK2 mRNA expression was evaluated using quantitative reverse transcription-polymerase chain reaction. RESULTS: Only 133 of the 197 patients (67.5%) were found to be HER2-positive by central assessment. CDKN1B mRNA expression was strongly correlated with Src (rho = 0.71) and JAK2 (rho = 0.54). In HER2-positive patients, low CDKN1B conferred higher risk for progression [hazard ratio (HR) = 1.58, 95% confidence interval (CI) 1.08-2.32, P = .018]. In HER2-negative patients, low Src was associated with longer survival (HR = 0.56, 95% CI 0.32-0.99, P = .045). Upon multivariate analyses, only low CDKN1B and JAK2 mRNA expression remained unfavorable factors for PFS in de novo and relapsed (R)-MBC patients, respectively (HR = 2.36, 95% CI 1.01-5.48, P = .046 and HR = 1.76, 95% CI 1.01-3.06, P = .047, respectively). CONCLUSIONS: Low CDKN1B and JAK2 mRNA expressions were unfavorable prognosticators in a cohort of T-treated MBC patients. Our results suggest that CDKN1B and JAK2, if validated, may serve as prognostic factors potentially implicated in T resistance, which seems to be associated with distinct pathways in de novo and R-MBC.

Therapeutic Efficiency of an External Chinese Herbal Formula of Mammary Precancerous Lesions by BATMAN-TCM Online Bioinformatics Analysis Tool and Experimental Validation.

Ruyan Neixiao Cream (RYNXC), a patented Chinese herbal formula, was reported to have the effect of treating mammary precancerous disease. In this study, we predicted the potential targets, pathways, and diseases of the ingredients contained in each herbal of RYNXC and constructed an ingredients-targets-diseases network. Then, we analyzed molecular mechanisms of this Chinese herbal formula by MCF-10AT cells and model rats of breast precancerous lesions. BATMAN-TCM prediction showed that ESR1, PGR, PTGS2, EGFR, and Src were mRNA targets of RYNXC. Our results suggested that RYNXC transdermal fluid downregulated ESR1, PGR, PTGS2, EGFR, and Src expression at gene and protein level in MCF-10AT cells. In the rat breast precancerous lesions model, high and low dose RYNXC could also significantly reduce genes and proteins expression of ESR1, PGR, PTGS2, EGFR, and Src. Taken together these data indicate that RYNXC targets multiple molecules responsible for breast precancerous lesion and is an effective Chinese herbal formula. So RYNXC may be a promising external drug for breast precancerous lesions.

Abstract P2-08-20: Prognostic impact of SRC, CDKN1B and JAK2 expression in metastatic breast cancer patients treated with trastuzumab

Abstract Background-aim: SRC, CDKN1B and JAK2 play a crucial role in the coordination and facilitation of cell-signaling pathways controlling a wide range of cellular functions. In the present study, we investigated the prognostic significance and clinical utlity of these biomarkers in metastatic breast cancer (MBC) patients treated with trastuzumab (T). Methods: We assessed SRC, CDKN1B and JAK2 mRNA expression with qRT-PCR (Taqman-MGB assays) on 197 paraffin tumors. PIK3CA mutation status was previously assessed. Relapsed (RMBC) and de novo MBC (dnMBC) patients had received T for metastatic disease only. Tumors were centrally re-assessed for HER2 status. Results: Only 133/197 patients (67.5%) were found to be truly HER2(+). CDKN1B mRNA expression strongly correlated with SRC (rho = 0.71) and JAK2 (rho = 0.54); high CDKN1B was more frequent in RMBC compared to dnMBC (p = 0.001) and in PIK3CA wild-type tumors (p = 0.005). In HER2(+) patients, low CDKN1B conferred higher risk for progression (HR 1.58, 95% CI 1.08-2.32, p = 0.018). In HER2(-) patients, low SRC was associated with longer survival (HR 0.56, 95% CI 0.32-0.99, p = 0.045) and, as a trend, with increased progression-free survival (PFS) (p = 0.067). For PFS, in RMBC, we observed trends for unfavorable low CDKN1B (p = 0.068) and JAK2 (p = 0.086); similarly, in dnMBC for unfavorable low CDKN1B (p = 0.072). Low SRC showed a trend for better survival in RMBC (p = 0.087). Upon multivariable analyses, only PIK3CA mutations strongly predicted for unfavorable PFS in HER2(+) patients (HR 3.37, 95% CI 1.98-5.73, p < 0.001). Low CDKN1B and JAK2 mRNA expression remained unfavorable factors for PFS in dnMBC and RMBC patients (HR 2.36, 95% CI 1.01-5.48, p = 0.046 and HR 1.76, 95% CI 1.01-3.06, p = 0.047, respectively). Conclusions: Low CDKN1B and JAK2 mRNA expression were unfavorable prognosticators in a cohort of T-treated MBC patients previously unexposed to this agent, with distinct impact in de novo and RMBC. Our results highlight biological and clinical differences between de novo and RMBC and suggest that CDKN1B and JAK2, if validated, may serve as prognostic factors potentially implicated in T-resistance, which seems to be associated with distinct pathways in the two MBC settings. Citation Format: Economopoulou P, Kotoula V, Koliou G-A, Papadopoulou K, Christodoulou C, Pentheroudakis G, Koutras A, Bafaloukos D, Papakostas P, Pectasides D, Kotsakis A, Razis E, Samantas E, Kalogeras KT, Economopoulos T, Fountzilas G. Prognostic impact of SRC, CDKN1B and JAK2 expression in metastatic breast cancer patients treated with trastuzumab [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-20.

The Amide Local Anesthetic Ropivacaine Attenuates Acute Rejection After Allogeneic Mouse Lung Transplantation.

Acute allograft rejection after lung transplantation remains an unsolved hurdle. The pathogenesis includes an inflammatory response during and after transplantation. Ropivacaine, an amide-linked local anesthetic, has been shown to attenuate lung injury due to its anti-inflammatory effects. We hypothesized that the drug would also be able to attenuate acute rejection (AR) after allogeneic lung transplantation. Allogeneic, orthotopic, single left lung transplantation was performed between BALB/c (donors) and C57BL/6 (recipients) mice. Prior to explantation, lungs were flushed with normal saline with or without ropivacaine (final concentration 1µM). Plasma levels of tumor necrosis factor-α and interleukins - 6 and - 10 were measured 3h after transplantation by ELISA. Lung function was assessed on postoperative day five and transplanted lungs were analyzed using histology (AR), immunohistochemistry (infiltrating leukocytes) and Western blot (phosphorylation and expression of Src and caveolin-1). Ropivacaine pre-treatment significantly reduced AR scores (median 3 [minimum-maximum 2-4] for control vs. 2 [1-2] for ropivacaine, p < 0.001) and plasma levels of tumor necrosis factor-α (p = 0.01) compared to control, whereas plasma concentrations of interleukin - 6 (p = 0.008) and - 10 (p < 0.001) were increased by ropivacaine. The number of T-lymphocytes infiltrating the transplanted lung was attenuated (p = 0.02), while no differences in macrophage or B-lymphocyte numbers could be observed after ropivacaine pre-treatment. Caveolin-1 phosphorylation in ropivacaine-treated lungs was diminished (p = 0.004). Pre-treatment of donor lungs with the local anesthetic ropivacaine diminished histological signs of AR after orthotopic left lung transplantation in mice, most likely due to reduced infiltration of T-lymphocytes into the graft.

Kinome-Wide siRNA Screening Identifies Src-Enhanced Resistance of Chemotherapeutic Drugs in Triple-Negative Breast Cancer Cells.

Background: Chemotherapy is the main treatment for triple-negative breast cancer (TNBC), which lack molecular markers for diagnosis and therapy. Cancer cells activate chemoresistant pathways and lead to therapeutic failure for patients with TNBC. Several kinases have been identified as chemoresistant genes. However, the involvement of kinases in the chemoresistance in TNBC cells is not fully understood.Methods: We employed a kinome siRNA library to screen whether targeting any kinases could increase the chemosensitivity of TNBC cell lines. The effects of kinase on cell viability in various breast cancer cells were validated with ATP level and colony formation. Protein expression and phosphorylation were determined by immunoblotting. The Cancer Genome Atlas (TCGA) dataset was collected to analyze the correlation of Src expression with prognosis of TNBC patients.Results: Primary screening and validation for the initial hits showed that Src kinase was a potential doxorubicin-resistant kinase in the TNBC cell lines MDA-MB-231 and Hs578T. Both siRNA against Src and the Src inhibitor dasatinib enhanced the cytotoxic effects of doxorubicin in TNBC cells. Moreover, phosphorylation of AKT and signal transducer and activator of transcription 3 (STAT3), downstream effectors of Src, were accordingly decreased in Src-silenced or -inhibited TNBC cells. Additionally, TCGA data analysis indicated that Src expression levels in tumor tissues were higher than those in tumor-adjacent normal tissues in patients with TNBC. High co-expression level of Src and STAT3 was also significantly correlated with poor prognosis in patients.Conclusion: Our results showed that Src-STAT3 axis might be involved in chemoresistance of TNBC cells.

SRC inhibition prevents P-cadherin mediated signaling and function in basal-like breast cancer cells

BackgroundBasal-like breast cancer (BLBC) is a poor prognosis subgroup of triple-negative carcinomas that still lack specific target therapies and accurate biomarkers for treatment selection. P-cadherin is frequently overexpressed in these tumors, promoting cell invasion, stem cell activity and tumorigenesis by the activation of Src-Family kinase (SRC) signaling. Therefore, our aim was to evaluate if the treatment of BLBC cells with dasatinib, the FDA approved SRC inhibitor, would impact on P-cadherin induced tumor aggressive behavior.MethodsP-cadherin and SRC expression was evaluated in a series of invasive Breast Cancer and contingency tables and chi-square tests were performed. Cell-cell adhesion measurements were performed by Atomic Force Microscopy, where frequency histograms and Gaussian curves were applied. 2D and 3D cell migration and invasion, proteases secretion and self-renew potential were evaluated in vitro. Student’s t-tests were used to determine statistically significant differences. The cadherin/catenin complex interactions were evaluated by in situ proximity-ligation assay, and statistically significant results were determined by using Mann-Whitney test with a Bonferroni correction. In vivo xenograft mouse models were used to evaluate the impact of dasatinib on tumor growth and survival. ANOVA test was used to evaluate the differences in tumor size, considering a confidence interval of 95%. Survival curves were estimated by the Kaplan-Meier’s method, using the log-rank test to assess significant differences for mice overall survival.ResultsOur data demonstrated that P-cadherin overexpression is significantly associated with SRC activation in breast cancer cells, which was also validated in a large series of primary tumor samples. SRC activity suppression with dasatinib significantly prevented the in vitro functional effects of P-cadherin overexpressing cells, as well as their in vivo tumorigenic and metastatic ability, by increasing mice overall survival. Mechanistically, SRC inhibition affects P-cadherin downstream signaling, rescues the E-cadherin/p120-catenin complex to the cell membrane, recovering cell-cell adhesion function.ConclusionsIn conclusion our findings show that targeting P-cadherin/SRC signaling and functional activity may open novel therapeutic opportunities for highly aggressive and poor prognostic basal-like breast cancer.

Scavenger receptor-C acts as a receptor for Bacillus thuringiensis vegetative insecticidal protein Vip3Aa and mediates the internalization of Vip3Aa via endocytosis

The vegetative insecticidal proteins (Vip), secreted by many Bacillus thuringiensis strains during their vegetative growth stage, are genetically distinct from known insecticidal crystal proteins (ICPs) and represent the second-generation insecticidal toxins. Compared with ICPs, the insecticidal mechanisms of Vip toxins are poorly understood. In particular, there has been no report of a definite receptor of Vip toxins to date. In the present study, we identified the scavenger receptor class C like protein (Sf-SR-C) from the Spodoptera frugiperda (Sf9) cells membrane proteins that bind to the biotin labeled Vip3Aa, via the affinity magnetic bead method coupled with HPLC-MS/MS. We then certified Vip3Aa protoxin could interact with Sf-SR-C in vitro and ex vivo. In addition, downregulation of SR-C expression in Sf9 cells and Spodoptera exigua larvae midgut reduced the toxicity of Vip3Aa to them. Coincidently, heterologous expression of Sf-SR-C in transgenic Drosophila midgut significantly enhanced the virulence of Vip3Aa to the Drosophila larvae. Moreover, the complement control protein domain and MAM domain of Sf-SR-C are involved in the interaction with Vip3Aa protoxin. Furthermore, endocytosis of Vip3Aa mediated by Sf-SR-C correlates with its insecticidal activity. Our results confirmed for the first time that Sf-SR-C acts as a receptor for Vip3Aa protoxin and provides an insight into the mode of action of Vip3Aa that will significantly facilitate the study of its insecticidal mechanism and application.

Mechanistic insights of epithelial protein lost in neoplasm in prostate cancer metastasis.

EPLIN is frequently downregulated or lost in various cancers. The purpose of this study was to evaluate the importance of EPLIN in prostate cancer progression, with particular focus on the mechanistic implications to elucidate EPLIN's tumor suppressive function in cancer. EPLIN expression was evaluated in prostate cancer cell lines and tissues. PC-3 and LNCaP EPLINα overexpression models were generated through transfection with EPLINα sequence and EPLIN knockdown was achieved using shRNA in CA-HPV-10 cells. Functional assays were performed to evaluate cellular characteristics and potential mechanisms were evaluated using a protein microarray, and validated using western blot analysis. EPLIN expression was reduced in clinical prostate cancer sections, including hyperplasia (p ≤ 0.001) and adenocarcinoma (p = 0.005), when compared to normal prostate tissue. EPLINα overexpression reduced cell growth, migration and invasion, and influenced transcript, protein and phosphoprotein expression of paxillin, FAK and Src. EPLIN knockdown increased the invasive and migratory nature of CA-HPV-10 cells and also induced changes to FAK and Src total and/or phospho expression. Functional characterization of cellular migration and invasion in addition to FAK and Src inhibition demonstrated differential effects between control and EPLINα overexpression and EPLIN knockdown cell lines. This study highlights that EPLIN expression in prostate cancer is able to influence several aspects of cancer cell characteristics, including cell growth, migration and invasion. The mechanism of the tumor suppressive action of EPLIN remains to be fully elucidated; and this study proposes a role for EPLIN's ability to regulate the aggressive characteristics of prostate cancer cells partially through regulating FAK/Src signaling.

Severe hypoxia increases expression of ATM and DNA-PKcs and it increases their activities through Src and AMPK signaling pathways

BackgroundSolid tumors often contain hypoxic regions because an abnormal and inefficient tumor vasculature is unable to supply sufficient oxygen. Tissue hypoxia is generally defined as a low oxygen concentration of less than 2%. It is well known that tumor cells under severe hypoxia, where oxygen concentration is less than 0.1%, show radioresistance. It has been reported that cells under severe hypoxia show different responses from those under mild hypoxia, where oxygen concentration is 0.5–2.0%. In the present study, we investigated the effects of severe hypoxia on expression and activities of ATM and DNA-dependent protein kinase catalytic subunit (DNA-PKcs), both of which regulate DNA double-strand breaks (DSBs) repair and radiation sensitivity. Signaling pathways for increasing expression and activities of ATM and DNA-PKcs under severe hypoxia were also investigated. MethodsSV40-transformed human fibroblast cell lines, LM217 and LM205, and normal human dermal fibroblasts (NHDF) were used. Cells were cultured at an oxygen concentration of less than 0.05% for 12 or 24 h. Activities and/or expression of ATM, DNA-PKcs, Src, Caveolin-1, EGFR, HIF-1α, PDK1, Akt, AMPKα, and mTOR were estimated by Western blot analyses. ResultsSevere hypoxia increased expression and activities of ATM, DNA-PKcs, Src, Caveolin-1, EGFR, PDK1, Akt, and AMPKα, and decreased expression and activity of mTOR. A specific Src inhibitor, PP2 suppressed activation of ATM, DNA-PKcs, Caveolin-1, EGFR, and Akt under severe hypoxia. Treatment with siRNA for AMPKα suppressed activation of ATM and DNA-PKcs and increase of ATM expression under severe hypoxia. ConclusionOur data show that severe hypoxia increases activities of ATM and DNA-PKcs through Src and AMPK signaling pathways, and that activation of AMPK under hypoxia causes increase of ATM expression. Since ATM and DNA-PKcs play important roles in DSBs repair induced by ionizing radiation, those data provide novel insights on the molecular mechanism of the cellular radioresistance under severe hypoxia.

Skullcapflavone II inhibits osteoclastogenesis by regulating reactive oxygen species and attenuates the survival and resorption function of osteoclasts by modulating integrin signaling.

Many bone diseases, such as osteoporosis and rheumatoid arthritis, are attributed to an increase in osteoclast number or activity; therefore, control of osteoclasts has significant clinical implications. This study shows how skullcapflavone II (SFII), a flavonoid with anti-inflammatory activity, regulates osteoclast differentiation, survival, and function. SFII inhibited osteoclastogenesis with decreased activation of MAPKs, Src, and cAMP response element-binding protein (CREB), which have been known to be redox sensitive. SFII decreased reactive oxygen species by scavenging them or activating nuclear factor-erythroid 2-related factor 2 (Nrf2), and its effects were partially reversed by hydrogen peroxide cotreatment or Nrf2 deficiency. In addition, SFII attenuated survival, migration, and bone resorption, with a decrease in the expression of integrin β3, Src, and p130 Crk-associated substrate, and the activation of RhoA and Rac1 in differentiated osteoclasts. Furthermore, SFII inhibited osteoclast formation and bone loss in an inflammation- or ovariectomy-induced osteolytic mouse model. These findings suggest that SFII inhibits osteoclastogenesis through redox regulation of MAPKs, Src, and CREB and attenuates the survival and resorption function by modulating the integrin pathway in osteoclasts. SFII has therapeutic potential in the treatment and prevention of bone diseases caused by excessive osteoclast activity.-Lee, J., Son, H. S., Lee, H. I., Lee, G.-R., Jo, Y.-J., Hong, S.-E., Kim, N., Kwon, M., Kim, N. Y., Kim, H. J., Lee, Y. J., Seo, E. K., Jeong, W. Skullcapflavone II inhibits osteoclastogenesis by regulating reactive oxygen species and attenuates the survival and resorption function of osteoclasts by modulating integrin signaling.

Abstract P337: Src Signaling and Toll-like Receptor 4 (TLR4) are Involved in Ouabain-induced Endothelial Cell Inflammation

Controversial evidence indicates that endogenous ouabain, a cardiotonic steroid can be synthesized in the adrenal cortex and hypothalamus and secreted as a hormone reaching nanomolar concentrations in the blood. The steroid has pathophysiological significance since its blood levels are positively correlated with blood pressure elevation. Inflammation of the vascular wall and endothelial dysfunction contribute to vascular stiffening in hypertension and it has been proposed that the endothelium is a site of action of ouabain. We hypothesized that ouabain would increase pro-inflammatory events in the endothelium. We observed that a low concentration ouabain (10nM; 24hr) sharply increased mRNA levels of the pro-inflammatory cytokines compared to control group (vehicle; 24h), TNF-α (59.9 fold vs con), IL-1β (3.23 fold vs con), COX2 (309.08 fold vs con), IL-6 (5.76 fold vs con) in cultured, human aortic endothelial cell (HAEC) and increased cyclooxygenase (COX2) expression (1.78 fold vs con). Simultaneously, a burst of nitric oxide (NO) was produced (1.2 fold vs con). Thus, low nanomolar concentrations of ouabain induced endothelial cell inflammation and dysfunction. Additionally, we observed that ouabain (10nM; 24hr) decreased mRNA expression of epidermal growth factor receptor (EGFR) (0.31 fold decrease vs con), and decreased the protein expression of EGFR (0.23 fold decrease vs con). But we found that ouabain induced the expression of non-receptor tyrosine kinase Src (2.27 fold vs con) and Toll-like receptor 4 (TLR4) (2.03 fold vs con), and activated the downstream signaling molecules, Myd88 (1.69 fold vs con), Akt (P-AKT/AKT, 4.31 fold vs con). Overall, the results provide a mechanism for ouabain-induced endothelial cell inflammation involving the inhibition of EGFR and the activation of Src and TLR4 to induce Akt signaling leading to secretion of pro-inflammatory cytokines.

The mechanisms of colorectal cancer cell mesenchymal–epithelial transition induced by hepatocyte exosome-derived miR-203a-3p

Abstract Phosphatase of regenerating liver 3 (PRL3) promotes colorectal cancer (CRC) metastasis by inducing epithelial-to-mesenchymal transition. Mesenchymal-to-epithelial transition (MET), the opposite of epithelial-to-mesenchymal transition, has been proposed as a mechanism for the establishment of metastatic neoplasms. However, the molecular mechanism of MET remains unclear. Here, we show that miR-203a-3p derived from hepatocyte exosomes inhibits Src expression, reduces epidermal growth factor receptor activity and downstream signaling pathways, and increases E-cadherin expression, which is a typical mesenchymal cell marker of MET, in CRC cells. These results show the important role of epidermal growth factor receptor in CRC cell MET.

Zinc induces CDK5 activation and neuronal death through CDK5-Tyr15 phosphorylation in ischemic stroke

CDK5 activation promotes ischemic neuronal death in stroke, with the recognized activation mechanism being calpain-dependent p35 cleavage to p25. Here we reported that CDK5-Tyr15 phosphorylation by zinc induced CDK5 activation in brain ischemic injury. CDK5 activation and CDK5-Tyr15 phosphorylation were observed in the hippocampus of the rats that had been subjected to middle cerebral artery occlusion, both of which were reversed by pretreatment with zinc chelator; while p35 cleavage and calpain activation in ischemia were not reversed. Zinc incubation resulted in CDK5-Tyr15 phosphorylation and CDK5 activation, without increasing p35 cleavage in cultured cells. Site mutation experiment confirmed that zinc-induced CDK5 activation was dependent on Tyr15 phosphorylation. Further exploration showed that Src kinase contributed to zinc-induced Tyr15 phosphorylation and CDK5 activation. Src kinase inhibition or expression of an unphosphorylable mutant Y15F-CDK5 abolished Tyr15 phosphorylation, prevented CDK5 activation and protected hippocampal neurons from ischemic insult in rats. We conclude that zinc-induced CDK5-Tyr15 phosphorylation underlies CDK5 activation and promotes ischemic neuronal death in stroke.

The Na,K-ATPase-Dependent Src Kinase Signaling Changes with Mesenteric Artery Diameter.

Inhibition of the Na,K-ATPase by ouabain potentiates vascular tone and agonist-induced contraction. These effects of ouabain varies between different reports. In this study, we assessed whether the pro-contractile effect of ouabain changes with arterial diameter and the molecular mechanism behind it. Rat mesenteric small arteries of different diameters (150–350 µm) were studied for noradrenaline-induced changes of isometric force and intracellular Ca2+ in smooth muscle cells. These functional changes were correlated to total Src kinase and Src phosphorylation assessed immunohistochemically. High-affinity ouabain-binding sites were semi-quantified with fluorescent ouabain. We found that potentiation of noradrenaline-sensitivity by ouabain correlates positively with an increase in arterial diameter. This was not due to differences in intracellular Ca2+ responses but due to sensitization of smooth muscle cell contractile machinery to Ca2+. This was associated with ouabain-induced Src activation, which increases with increasing arterial diameter. Total Src expression was similar in arteries of different diameters but the density of high-affinity ouabain binding sites increased with increasing arterial diameters. We suggested that ouabain binding induces more Src kinase activity in mesenteric small arteries with larger diameter leading to enhanced sensitization of the contractile machinery to Ca2+.

Highlights of This Issue

The identification of biomarkers that can predict therapeutic outcomes in response to PD-1 or PD-L1 immune checkpoint inhibitors remains an unmet need in the treatment of NSCLC and urothelial cancer. To identify a predictive biomarker for durvalumab, an anti-PD-L1 monoclonal antibody, Higgs and colleagues performed RNA sequencing of biopsies from NSCLC and urothelial cancer patients enrolled in a nonrandomized phase Ib/II clinical trial (NCT01693562). Their results demonstrate that gene expression levels of four IFNγ-inducible mRNAs correlate with improved clinical outcomes in durvalumab-treated patients with NSCLC or urothelial cancer. This IFNγ gene signature may augment the predictive value of PD-L1 and other biomarkers in identifying those cancer patients who are most likely to respond to therapy with durvalumab or other immune checkpoint inhibitors, independently of PD-L1 assessed by immunohistochemistry.To determine whether the 21-gene recurrence score can predict benefit of postmastectomy radiotherapy (PMRT) in women with ER-positive T1-2 N1 breast cancer, Goodman and colleagues performed an observational cohort study using the National Cancer Database as a discovery cohort and the SEER registry as a validation cohort. Women with low-risk recurrence scores derived a significant survival benefit from PMRT, while women with intermediate- and high-risk scores did not. Women at the lowest risk of distant failure may, therefore, derive the greatest benefit from aggressive locoregional therapy with PMRT.The poor response of advanced stage ovarian clear cell carcinoma (OCCC) towards platinum-based chemotherapy urges alternative therapeutic strategies. Caumanns and colleagues performed a comprehensive kinome-wide screen in a large set of OCCC patients and reported numerous genomic alterations related to mTORC1/2 activation. Ubiquitous expression of mTORC1/2 downstream target p-S6 in OCCC patients and the high sensitivity of OCCC cell lines and patient-derived xenografts to mTORC1/2 inhibitors indicate the clinical relevance of these genomic alterations. These findings propose further exploration of mTORC1/2 inhibitors, currently being evaluated in phase II clinical trials in OCCC patients.Epithelial-to-mesenchymal transition (EMT) plays a critical role in tumor invasion and metastasis. Integrating findings from a human papillomavirus-16 E6/E7 oncoprotein driven model of invasion with analysis of patient samples and TCGA RNA-seq, Srivastava and colleagues identify Slug as the major modulator of EMT in head and neck squamous cell carcinoma (HNSCC). Expression of the p63 isoform ΔNp63γ is necessary and sufficient to induce Slug and EMT, which requires signaling through the activity of another p63 target Src. Elevated expression of Src associates with worse outcome in HNSCC; thus clinical efforts targeting Src hold promise in poor prognosis HNSCC.

Abstract A04: Dasatinib shows different cytotoxicity in triple-negative breast cancer cell lines

Abstract Background: Triple-negative breast cancer (TNBC) is defined by the lack of significant expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2). Thus, TNBC is resistant to existing molecular targeted drugs such as trastuzumab or tamoxifen, and has a worse prognosis than non-TNBC. In addition, recent studies suggest that TNBC may represent a heterogeneous group of tumors with regards to gene expression, prognosis, and chemotherapy response. Although various molecular targeted drugs for TNBC have been attempted in clinical trials, almost all were negative outcomes because TNBC patients have a heterogeneous behavior. Therefore, in order to establish an efficient therapy, it is important to investigate the difference in response to molecular targeted drugs. From this viewpoint, we focused on dasatinib (Bcl-Abl/Src kinase inhibitor, approved in chronic myeloid leukemia) for the reason that it has been shown to be effective in some patients, even though it failed in clinical trials of unselected TNBC patients in the past. Here, to elucidate the mechanism of different response in dasatinib treatment on TNBC, we attempted to analyze the effects of dasatinib on cytotoxicity in some kinds of TNBC cell lines and to analyze the expression of targeted protein (Src) expression as a first step for elucidating the molecular mechanism of some kinds of TNBC cell lines. Methods: In this study, we used four TNBC cell lines such as HCC1806, HCC1395, MDA-MB-453, and MDA-MB-436, and one non-TNBC cell line, MCF-7. These cells were treated with a range of concentrations of dasatinib (0.001, 0.01, 0.1, 1, 10, or 100 μM) for 72 h. After treatment, cytotoxicity was evaluated by WST-8 assay and molecular expression was examined by Western blotting. Results and Discussion: WST-8 assay revealed that dasatinib showed high cytotoxicity in MCF7, HCC1395, and HCC1806 (IC50 were 0.162, 0.490, and 0.110 μM, respectively). Compared to these three cell lines, dasatinib showed low cytotoxicity in MDA-MB-453 and MDA-MB-436 (IC50 were 6.93 and 7.59 μM, respectively). Then, to investigate the mechanism that the dasatinib showed the different cytotoxicity among these cell lines, the expression of Src, target of dasatinib was examined. The higher expression of Src was observed in three cell lines, indicating relatively high cytotoxicity for dasatinib than the others. Although expression of Src was not observed in MDA-MB-453, that in MDA-MB-436 was the same extent as MCF7 despite low cytotoxicity for dasatinib. Thus, we evaluated the protein activity downstream of the Src pathway. Regarding the three cell lines in which dasatinib showed relatively high cytotoxicity, the phosphorylation of Akt after dasatinib treatment was degraded. However, there was no significant change of Akt activity in the two cell lines that showed relatively low cytotoxicity on dasatinib treatment. Now, in order to elucidate the molecular mechanism of dasatinib resistance observed in MDA-MB-436, we focus on autophagy that has reported to be suppressed by Src. In this regard, we indicated that the expression of LC3-II, known as a marker for autophagy, was higher in MDA-MB-436 than that of other cells in this study. Therefore, we are trying to clarify the relationship between Src and LC3-II. Conclusions: Each TNBC cell line shows the different response to dasatinib and the different Src expression, suggesting that the efficacy of dasatinib could not be dependent on the expression of Src. Thus, to clarify the mechanism of differences of cytotoxicity caused from a variety of TNBC cell lines, it is necessary to analyze more protein expressions upstream or downstream of the Src pathway. Citation Format: Yuya Haga, Kazuma Higashisaka, Lili Yang, Naoki Sekine, Kazuya Nagano, Yasuo Tsutsumi. Dasatinib shows different cytotoxicity in triple-negative breast cancer cell lines [abstract]. In: Proceedings of the AACR Special Conference: Advances in Breast Cancer Research; 2017 Oct 7-10; Hollywood, CA. Philadelphia (PA): AACR; Mol Cancer Res 2018;16(8_Suppl):Abstract nr A04.