BACKGROUND: c-Src is a driver oncogene well-known for tumorigenic signaling, but little for metabolic function. Previous reports about c-Src regulation of glucose metabolism prompted us to investigate its function in other nutrient modulation, particularly in lipid metabolism.
METHODS: Oil-red O staining, cell growth assay, and tumor volume measurement were performed to determine lipid amount and growth inhibitory effect of treatments in lung cancer cells and xenograft model. Gene expression was evaluated by immunoblotting and relative RT-PCR. Transcriptional activity of peroxisome proliferator-activated receptor gamma (PPARγ) was assessed by luciferase assay. Reactive oxygen species (ROS) was measured using ROS sensing dye. Oxygen consumption rate was evaluated by Seahorse XF Mito Stress Test. Clinical relevance of candidate proteins was examined using patient samples and public database analysis.
FINDINGS: Inhibition of Src induced lipolysis and increased intracellular ROS. Src inhibition derepressed PPARγ transcriptional activity leading to induced expression of lipolytic gene fatty acid binding protein (FABP) 4 which accompanies reduced lipid droplets and decreased tumor growth. The reverse correlation of Src and FABP4 was confirmed in pair-matched lung cancer patient samples, and further analysis using public datasets revealed upregulation of lipolytic genes is associated with better prognosis of cancer patients.
INTERPRETATION: This study provides an insight of how oncogenic factor Src concurrently regulates both cellular signaling pathways and metabolic plasticity to drive cancer progression. FUND: National Research Foundation of Korea and Korea Health Industry Development Institute.

BACKGROUND: Chromatin modification at mitosis is closely related to transcriptional reactivation in the subsequent cell cycle. We reasoned this process is deregulated by oncogenic signals, which would contribute to mitotic stress resistance in pancreatic cancer. Here, we show DMAP1/Bub3 complex mediates mitotic stress-induced cellular apoptosis, while this effect is counteracted by c-Src in pancreatic cancer cells. Our study aims to uncover an unidentified mechanism underlying the distinct response to mitotic stress between normal cells and pancreatic cancer cells.
METHODS: The interaction between Bub3 and DMAP1 upon mitotic stress signaling was determined through molecular and cell biological methods. The inhibitory effect of c-Src on DMAP1/Bub3-mediated DNA methylation and gene transcription profile was investigated. The association between c-Src-mediated DMAP1 phosphorylation and paclitaxel activity in vivo and clinicopathologic characteristics were analyzed.
RESULTS: Mitotic arrest induced p38-dependent phosphorylation of Bub3 at Ser211, which promotes DMAP1/Bub3 interaction. DMAP1/Bub3 complex is recruited by TAp73 to the promoter of anti-apoptotic gene BCL2L1, thus mediates the DNA methylation and represses gene transcription linked to cell apoptosis. Meanwhile, DMAP1 was highly phosphorylated at Tyr 246 by c-Src in pancreatic cancer cells, which impedes DMAP1/Bub3 interaction and the relevant cellular activites. Blocking DMAP1 pTyr-246 potentiates paclitaxel-inhibited tumor growth. Clinically, DMAP1 Tyr 246 phosphorylation correlates with c-Src activity in human pancreatic cancer specimens and poor prognosis in pancreatic cancer patients.
CONCLUSIONS: Our findings reveal a regulatory role of Bub3 in DMAP1-mediated DNA methylation upon mitotic stress and provide the relevance of DMAP1 pTyr-246 to mitotic stress resistance during pancreatic cancer treatment.

The survival and growth of multiple myeloma (MM) cells are facilitated by cell-cell interactions with bone marrow stromal cells and the bone marrow microenvironment. These interactions induce de novo drug resistance known as cell adhesion-mediated drug resistance. Our previous results recently revealed that the receptor activator of NF-κB (RANK) ligand (RANKL), which is expressed by bone marrow stromal cells, contributes to anti-cancer drug resistance through the activation of various signaling molecules and suppression of Bim expression in RANK-expressing MM cells. However, the detailed mechanisms underlying RANKL-induced drug resistance remain uncharacterized. In the present study, we investigated the mechanism of RANKL-induced drug resistance in RANK-expressing MM cell lines. We found treatment of MM cells with RANKL-induced c-Src phosphorylation and activation of the downstream signaling molecules Akt, mTOR, STAT3, JNK, and NF-κB. In addition, treatment with dasatinib, a c-Src inhibitor, overcame RANKL- and bone marrow stromal cell-induced drug resistance to adriamycin, vincristine, dexamethasone, and melphalan by suppressing c-Src, Akt, mTOR, STAT3, JNK, and NF-κB activation and enhancing expression of Bim. Overall, RANKL- and bone marrow stromal cell-induced drug resistance correlated with the activation of c-Src signaling pathways, which caused a decrease in Bim expression. Dasatinib treatment of RANK-expressing MM cells re-sensitized them to anti-cancer drugs. Therefore, inhibition of c-Src may be a new therapeutic approach for overcoming RANKL-induced drug resistance in patients with MM.

Multiple myeloma (MM, plasma cell myeloma) is a malignant hematologic disease characterized by the clonal proliferation of malignant plasma cells. The treatment of MM has changed dramatically in recent years, with the introduction of new drugs into therapeutic strategies, both in the front line setting and in relapsed refractory disease. However, most patients eventually relapse and often demonstrate multiple drug resistance. Therefore there is still an urgent and unmet need to define the molecular mechanisms of resistance for available drugs in order to enhance the use of existing treatments and design more effective therapies. Genetic abnormalities are well known to play a central role in MM resistance to available drugs, and epigenetic aberrations mainly affecting the patterns of DNA methylation and histone modifications of genes, especially tumor suppressors, can be involved in the resistance mechanism. Moreover, defects in the mechanisms of apoptosis, senescence and DNA repair could also contribute to drug resistance. In addition, mutations or alterations in the expression of the drug target can influence response to therapy. Achieving a better understanding of the pathways and protein expression involved in MM drug resistance and the development of novel therapeutic strategies are important goals for further progress in the treatment of MM. This review gives a critical overview of the role of cellular, microenvironmental and molecular mechanisms of drug resistance in MM.

Endocrine therapy resistance invariably develops in advanced estrogen receptor-positive (ER

OBJECTIVE: To examine the expression of hypoxia-inducible factor-1α (HIF-1α) and its related molecules (cellular repressor of E1A-stimulated genes [CREG], osteopontin [OPN], proto-oncogene tyrosine-protein kinase Src [c-Src], and vascular endothelial growth factor [VEGF]) in juvenile nasopharyngeal angiofibroma (JNA) and explore the correlation between clinical prognosis and HIF-1α expression.
METHODS: The study performed a retrospective review of the clinical records of patients with JNA treated between 2003 and 2007. Specimens were analyzed by immunohistochemistry for HIF-1α, CREG, OPN, c-Src, and VEGF expression, and microvessel density (MVD) was assessed by tissue microarray. The correlation between expression levels and clinicopathological features including age, tumor stage, intraoperative blood loss, and recurrence was analyzed.
RESULTS: HIF-1α, CREG, OPN, c-Src, and VEGF were upregulated in endothelial cells (ECs) of patients with JNA, and strong correlations in the expression of these molecules were observed. HIF-1α expression was higher in young patients ( P = .032) and in recurrent cases ( P = .01). Survival analysis showed that low HIF-1α levels in ECs predicted longer time to recurrence (log rank test P = .006). Receiver operating characteristic curve analysis showed that HIF-1α was a prognostic factor for recurrence (area under the curve = 0.690, P = .019). No correlation was found between the expression of molecules and Radkowski stage or intraoperative blood loss.
CONCLUSION: In cases of JNA treated surgically, HIF-1α expression in ECs is a useful prognostic factor for tumor recurrence.

BACKGROUND/AIM: Therapeutic options of locally advanced or metastatic head and neck squamous cell carcinoma (HNSCC) are limited. Src and cKIT are key protein regulators for local tumor progression. The aim of the study was to investigate the therapeutic potential of targeted therapies in human squamous cell carcinoma (HNSCC) in vitro. Therefore, the influence of the selective tyrosine kinase inhibitors niotinib, dasatinib, erlotinib, gefitinib and afatinib on Src and cKIT expression in Human papilloma virus (HPV)-positive and HPV-negative squamous cancer cells (SCC) was analyzed in vitro.
MATERIALS AND METHODS: ELISA was performed to evaluate the expression of Src and cKIT under the influence of nilotinib, dasatinib, erlotinib, gefitinib and afatinib (10 μmol/l) in HPV-negative and HPV-positive SCC (24-96 h of incubation).
RESULTS: Gefitinib significantly increased cKIT expression in HPV-positive and HPV-negative cells whereas nilotinib and afatinib decreased cKIT expression in HPV-positive SCC. The influence of tyrosine kinase inhibitors in HPV-negative SCC was marginal. Surprisingly, Src expression was significantly increased by all tested tyrosine kinase inhibitors in HPV-positive SCC.
CONCLUSION: The results revealed beneficial and unexpected information concerning the interaction of selective tyrosine kinase inhibitors and the tumor biology of HNSCC.

Posttranslational modifications of mammalian c-Src N-terminal and C-terminal domains regulate distinct functions. Myristoylation of G

Hepatitis B virus core protein (HBc) is expressed preferentially in hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC). HBc can function as an oncogene arising from its gene regulatory properties, but how it contributes functionally to hepatocarcinogenesis remains unclear. In this study, we determined the molecular and functional roles of HBc during HBV-associated hepatocellular tumorigenesis. HBc increased tumor formation of hepatoma cells. Moreover, expression of HBc specifically promoted proliferation of hepatoma cells in vitro. Mechanistic investigations revealed that these effects were caused by activation of the Src/PI3K/Akt pathway through proximal switch from inactive Src to the active form of the kinase by HBc. HBc-mediated sarcoma (Src) kinase activation was associated with down-regulation of C-terminal Src kinase (Csk). In addition, HBc enhances Src expression by activation of alternative Src 1A promoter in an Sp1 transcription factor-dependent manner. Proliferation induced by stable HBc expression was associated with increased G

MicroRNAs (miRNAs or miRs) have been shown to regulate hepatocellular carcinoma (HCC) metastasis. In the present study, we focused on the functions of miR-1271 in HCC metastasis. The downregulation of miR-1271 was found to be associated with to venous infiltration, an advanced TNM stage (III+IV stage) and a shorter survival time. Our in vitro and in vivo data demonstrated that miR-1271 prevented HCC cell migration and invasion, as well as the formation of lung metastatic clusters. In addition, miR-1271 was demonstrated to markedly inhibit the epithelial-mesenchymal transition (EMT) of HCC cells. Importantly, protein tyrosine phosphatase type IVA member 1 (PTP4A1) was identified as a direct downstream target of miR-1271 in HCC. Furthermore, we confirmed that the phosphorylation of c-Src at Tyr416 mediated by PTP4A1 was a potential anti-HCC mechanism of action of miR-1271. On the whole, our data indicate that miR-1271 inhibits HCC metastasis by targeting the PTP4A1/c-Src signaling pathway and may serve as a prospective cancer therapeutic target for HCC.

SRC family kinase was documented to have vital roles in adjusting cancer cell malignant behaviors. To date, the role of c-Src, a member of SRC family kinase, in resistance to paclitaxel in human ovarian cancer cells under hypoxia has not been investigated. In the present study, we discovered that hypoxic environment suppressed paclitaxel-induced G2/M phase arrest and blockade of c-Src improved ovarian cancer cells' sensitivity to paclitaxel. FV-429, a derivative of natural flavonoid wogonin, could suppress gene expression and activation of c-Src, followed by deteriorated Stat3 nuclear translocation and its binding to HIF-1α, resulting in paclitaxel resistance reversal through G2/M arrest potentiation. Our study demonstrated that c-Src contributed to hypoxic microenvironment-rendered paclitaxel resistance in human epithelial ovarian cancer cells by G2/M phase arrest deterioration, and through c-Src suppression, FV-429 was capable of reversing the resistance by blocking c-Src/Stat3/HIF-1α pathway.

PTPRA is reported to be involved in cancer development and progression through activating the Src family kinase (SFK) signaling pathways, however, the roles of PTPRA in the squamous cell lung cancer (SCC) development are unclear. The purpose of this study was to clarify the clinical relevance and biological roles of PTPRA in SCC. We found that PTPRA was upregulated in squamous cell lung cancer compared to matched normal tissues at the mRNA (N=20, P=0.004) and protein expression levels (N=75, P<0.001). Notably, high mRNA level of PTPRA was significantly correlated with poorer prognosis in 675 SCC patients from the Kaplan-Meier plotter database. With 75 cases, we found that PTPRA protein expression was significantly correlated with tumor size (P=0.002), lymph node metastasis (P=0.008), depth of tumor invasion (P<0.001) and clinical stage (P<0.001). The Kaplan-Meier plot suggested that high expression of PTPRA had poorer overall survival in SCC patients (P=0.009). Multivariate Cox regression analysis suggested that PTPRA expression was an independent prognostic factor in SCC patients. In the cellular models, PTPRA promotes SCC cell proliferation through modulating Src activation as well as cell cycle progression. In conclusion, higher PTPRA level was associated with worse prognosis of SCC patients and PTPRA could promote the cell cycle progression through stimulating the c-Src signaling pathways.

The relation between the tumor and its microenvironment is one of the most interesting and less understood issues. Recently, we showed a role of CCL20 chemokine in proning the healthy tissue neighboring the tumor to carcinogenesis. Besides, tumor-secreted CCL20 induced proliferation, migration, and EMT of healthy cells. In this context, we have studied here if CCL20 had effects on the migration of cancer cells and the intracellular pathways used in breast epithelial cells in primary culture. Using molecular (siRNA) and pharmacological (inhibitors) techniques, we found multiple signaling kinases to be activated and involved in CCL20-induced tumor breast cell migration. CCL20 provoked a 2.5-fold increase of cell migration and invasion; CCL20 also enhanced MMP- 2 and MMP-9 mRNAs/protein expression and activities. Cell migration and invasiveness due to CCL20 significantly decreased when MMP-2 and MMP-9 were inhibited in CCL20-stimulated cells. CCL20 controlled MMP-2 expression through the JAK2/STAT3 pathway, while the expression of MMP-9 occurred by PKC-α that activated, consequently, c-Src, Akt, and finally NF-kB. These results reveal a role for CCL20 also in tumor breast cell and point to CCL20 as a novel therapeutic target in cancer.

Diagnostic whole-body scan is a standard procedure in patients with thyroid cancer prior to the application of a therapeutic dose of

Chondrosarcoma is the second most prevalent general primary tumor of bone following osteosarcoma. Chondrosarcoma development may be linked to angiogenesis, which is principally elicited by vascular endothelial growth factor-A (VEGF-A). VEGF-A level has been recognized as a prognostic marker in angiogenesis. WNT1-inducible signaling pathway protein-3 (WISP)-3/CCN6 belongs to the CCN family and is involved in regulating several cellular functions, including cell proliferation, differentiation, and migration. Nevertheless, the effect of WISP-3 on VEGF-A production and angiogenesis in human chondrosarcoma remains largely unknown. This current study shows that WISP-3 promoted VEGF-A production and induced angiogenesis of human endothelial progenitor cells. Moreover, WISP-3-enhanced VEGF-A expression and angiogenesis involved the c-Src and p38 signaling pathways, while miR-452 expression was negatively affected by WISP-3 via the c-Src and p38 pathways. Our results illustrate the clinical significance of WISP-3, VEGF-A and miR-452 in human chondrosarcoma patients. WISP-3 may illustrate a novel therapeutic target in the metastasis and angiogenesis of chondrosarcoma.

Recent studies have shown that increased syndecan-1 (SDC1) expression in human glioma is associated with higher tumor grades and poor prognoses, but its oncogenic functions and the underlying molecular mechanisms remain unknown. Here, we examined SDC1 expression in datasets from The Cancer Genome Atlas and the National Center for Biotechnology Information Gene Expression Omnibus. Elevated SDC1 expression in glioma was closely associated with increases in tumor progression and shorter survival. We also examined SDC1 expression and evaluated the effects of stable SDC1 knockdown in glioma cell lines. SDC1 knockdown attenuated proliferation and invasion by glioma cells and markedly decreased PCNA and MMP-9 mRNA and protein expression. In a xenograft model, SDC1 knockdown suppressed the tumorigenic effects of U87 cells in vivo. SDC1 knockdown decreased phosphorylation of the c-src/FAK complex and its downstream signaling molecules, Erk, Akt and p38 MAPK. These results suggest that SDC1 may be a novel therapeutic target in the treatment of glioma.

The adaptor protein Srcin1 is a novel Src-binding protein that regulates Src activation through C-terminal Src kinase (Csk). Srcin1 behaves as a tumour suppressor in breast cancer, but the role of Srcin1 in the development of colorectal cancer (CRC) remains unknown. In the present study, Srcin1 expression in normal tissue was examined by tissue microarray and assessed by immunohistochemistry in 10 patients. In addition, the biological impact of Srcin1 knockdown on CRC cells was investigated in vitro and in vivo. The results showed that Srcin1 was expressed in different types of normal human tissues, whereas its expression was increased in human CRC tissues. Srcin1 expression also correlated with tumour progression. The suppression of Srcin1 induced cell differentiation and G0/G1 cell cycle arrest. Furthermore, Srcin1 increased cell growth as well as the capacity of migration and invasion in CRC cells. Srcin1 induced the activation of the Wnt/β-catenin signalling pathway. Moreover, Srcin1 suppression sensitized cancer cells to 5-fluorouracil (5-FU)-induced apoptosis in vitro and in vivo. Together, these results demonstrate that Srcin1 contributes to CRC carcinogenesis, invasion and metastasis. These findings provide a rationale for a mechanistic approach to CRC treatment based on the development of Srcin1-targeted therapies.

Previous reports show that miR-34a suppressed K-562 cell proliferation and contributed to megakaryocytic differentiation of K-562 cells. Here, we reported that miR-34a, a tumor suppressor gene, is down-regulated in the K-562 cells and chronic myeloid leukemia (CML) patients due to aberrant DNA hypermethylation. c-SRC is a target of miR-34a. Restoring miR-34a expression resulted in down-regulation of c-SRC and phosphorylated (Tyr416) c-SRC protein in K-562 cells, which consequently triggered suppression of the RAF/MEK/ERK signaling pathway to decrease cell proliferation.

Triple-negative breast cancers (TNBCs) are neither susceptible to endocrine therapy due to a lack of estrogen receptor α expression nor trastuzumab. TNBCs frequently overexpress epidermal growth factor receptor (EGFR) and membrane bound estrogen receptor, GPER. To a certain extent the growth of TNBCs is stimulated by 17β-estradiol via GPER. We analyzed whether inhibition of EGFR by gefitinib reduces the expression of GPER and subsequent signal transduction in TNBC cells. Dependence of proliferation on 17β-estradiol was determined using Alamar Blue assay. Expression of GPR30 and activation of c-src, EGFR and cAMP-responsive element binding (CREB) protein by 17β-estradiol was analyzed by western blotting. Expression of c-fos, cyclin D1 and aromatase was determined using RT-PCR. Gefitinib reduced GPER expression concentration‑ and time‑dependently. In HCC70 cells, GPER expression was reduced to 15±11% (p<0.05) after treatment with 200 nM gefitinib for four days, and in HCC1806 cells GPER expression was reduced to 39±5% (p<0.01) of the control. 17β-estradiol significantly increased the percentage of HCC1806 cells within 7 days to 145±29% of the control (HCC70, 110±8%). This increase in cell growth was completely prevented in both TNBC cell lines after GPR30 expression was downregulated by treatment with 200 nM gefitinib. In HCC1806 cells, activation of c-src was increased by 17β-estradiol to 350±50% (p<0.01), and gefitinib reduced src activation to 110%. Similar results were obtained in the HCC70 cells. Phosphorylation of EGFR increased to 240±40% (p<0.05) in the HCC1806 cells treated with 17β-estradiol (HCC70, 147±25%). Gefitinib completely prevented this activation. Phosphorylation of CREB and induction of c-fos, cyclin D1 and aromatase expression by 17β-estradiol were all prevented by gefitinib. These experiments conclusively show that reduction of GPER expression is a promising therapeutic approach for TNBC.

Casitas B-cell lymphoma (Cbl) family ubiquitin ligases negatively regulate tyrosine kinase-dependent signal transduction by promoting degradation of active kinases. We and others previously reported that loss of Cbl functions caused hyperproliferation in lymphoid and hematopoietic systems. Unexpectedly, Cbl deletion in Cbl-b-null, Cbl-c-null primary mouse mammary epithelial cells (MECs) (Cbl triple-deficiency) induced rapid cell death despite enhanced MAP kinase and AKT activation. Acute Cbl triple-deficiency elicited distinct transcriptional and biochemical responses with partial overlap with previously described cellular reactions to unfolded proteins and oxidative stress. Although the levels of reactive oxygen species were comparable, detergent-insoluble protein aggregates containing phosphorylated c-Src accumulated in Cbl triple-deficient MECs. Treatment with a broad-spectrum kinase inhibitor dasatinib blocked protein aggregate accumulation and restored in vitro organoid formation. This effect is most likely mediated through c-Src because Cbl triple-deficient MECs were able to form organoids upon shRNA-mediated c-Src knockdown. Taking these data together, the present study demonstrates that Cbl family proteins are required to protect MECs from proteotoxic stress-induced cell death by promoting turnover of active c-Src.

BACKGROUND: In high-grade serous ovarian cancer (HGSOC), intrinsic and/or acquired resistance against platinum-containing chemotherapy is a major obstacle for successful treatment. A low frequency of somatic mutations but frequent epigenetic alterations, including DNA methylation in HGSOC tumors, presents the cancer epigenome as a relevant target for innovative therapy. Patient-derived xenografts (PDXs) supposedly are good preclinical models for identifying novel drug targets. However, the representativeness of global methylation status of HGSOC PDXs compared to their original tumors has not been evaluated so far. Aims of this study were to explore how representative HGSOC PDXs are of their corresponding patient tumor methylome and to evaluate the effect of epigenetic therapy and cisplatin on putative epigenetically regulated genes and their related pathways in PDXs.
METHODS: Genome-wide analysis of the DNA methylome of HGSOC patients with their corresponding PDXs, from different generations, was performed using Infinium 450 K methylation arrays. Furthermore, we analyzed global methylome changes after treatment of HGSOC PDXs with the FDA approved demethylating agent decitabine and cisplatin. Findings were validated by bisulfite pyrosequencing with subsequent pathway analysis. Publicly available datasets comprising HGSOC patients were used to analyze the prognostic value of the identified genes.
RESULTS: Only 0.6-1.0 % of all analyzed CpGs (388,696 CpGs) changed significantly (p < 0.01) during propagation, showing that HGSOC PDXs were epigenetically stable. Treatment of F3 PDXs with decitabine caused a significant reduction in methylation in 10.6 % of CpG sites in comparison to untreated PDXs (p < 0.01, false discovery rate <10 %). Cisplatin treatment had a marginal effect on the PDX methylome. Pathway analysis of decitabine-treated PDX tumors revealed several putative epigenetically regulated pathways (e.g., the Src family kinase pathway). In particular, the C-terminal Src kinase (CSK) gene was successfully validated for epigenetic regulation in different PDX models and ovarian cancer cell lines. Low CSK methylation and high CSK expression were both significantly associated (p < 0.05) with improved progression-free survival and overall survival in HGSOC patients.
CONCLUSIONS: HGSOC PDXs resemble the global epigenome of patients over many generations and can be modulated by epigenetic drugs. Novel epigenetically regulated genes such as CSK and related pathways were identified in HGSOC. Our observations encourage future application of PDXs for cancer epigenome studies.

Kinases are therapeutically actionable targets. Kinase inhibitors targeting vascular endothelial growth factor receptors (VEGFR) and mammalian target of rapamycin (mTOR) improve outcomes in metastatic clear cell renal cell carcinoma (ccRCC), but are not curative. Metastatic tumor tissue has not been comprehensively studied for kinase gene expression. Paired intra-patient kinase gene expression analysis in primary tumor (T), matched normal kidney (N) and metastatic tumor tissue (M) may assist in identifying drivers of metastasis and prioritizing therapeutic targets. We compared the expression of 519 kinase genes using NanoString in T, N and M in 35 patients to discover genes over-expressed in M compared to T and N tissue. RNA-seq data derived from ccRCC tumors in The Cancer Genome Atlas (TCGA) were used to demonstrate differential expression of genes in primary tumor tissue from patients that had metastasis at baseline (n = 79) compared to those that did not develop metastasis for at least 2 years (n = 187). Functional analysis was conducted to identify key signaling pathways by using Ingenuity Pathway Analysis. Of 10 kinase genes overexpressed in metastases compared to primary tumor in the discovery cohort, 9 genes were also differentially expressed in TCGA primary tumors with metastasis at baseline compared to primary tumors without metastasis for at least 2 years: EPHB2, AURKA, GSG2, IKBKE, MELK, CSK, CHEK2, CDC7 and MAP3K8; p<0.001). The top pathways overexpressed in M tissue were pyridoxal 5'-phosphate salvage, salvage pathways of pyrimidine ribonucleotides, NF-kB signaling, NGF signaling and cell cycle control of chromosomal replication. The 9 kinase genes validated to be over-expressed in metastatic ccRCC may represent currently unrecognized but potentially actionable therapeutic targets that warrant functional validation.

BACKGROUND: The progression of colorectal cancer (CRC) involves recurrent amplifications/mutations in the epidermal growth factor receptor (EGFR) and downstream signal transducers of the Ras pathway, KRAS and BRAF. Whether genetic events predicted to result in increased and constitutive signaling indeed lead to enhanced biological activity is often unclear and, due to technical challenges, unexplored. Here, we investigated proliferative signaling in CRC using a highly sensitive method for protein detection. The aim of the study was to determine whether multiple changes in proliferative signaling in CRC could be combined and exploited as a "complex biomarker" for diagnostic purposes.
METHODS: We used robotized capillary isoelectric focusing as well as conventional immunoblotting for the comprehensive analysis of epidermal growth factor receptor signaling pathways converging on extracellular regulated kinase 1/2 (ERK1/2), AKT, phospholipase Cγ1 (PLCγ1) and c-SRC in normal mucosa compared with CRC stage II and IV. Computational analyses were used to test different activity patterns for the analyzed signal transducers.
RESULTS: Signaling pathways implicated in cell proliferation were differently dysregulated in CRC and, unexpectedly, several were downregulated in disease. Thus, levels of activated ERK1 (pERK1), but not pERK2, decreased in stage II and IV while total ERK1/2 expression remained unaffected. In addition, c-SRC expression was lower in CRC compared with normal tissues and phosphorylation on the activating residue Y418 was not detected. In contrast, PLCγ1 and AKT expression levels were elevated in disease. Immunoblotting of the different signal transducers, run in parallel to capillary isoelectric focusing, showed higher variability and lower sensitivity and resolution. Computational analyses showed that, while individual signaling changes lacked predictive power, using the combination of changes in three signaling components to create a "complex biomarker" allowed with very high accuracy, the correct diagnosis of tissues as either normal or cancerous.
CONCLUSIONS: We present techniques that allow rapid and sensitive determination of cancer signaling that can be used to differentiate colorectal cancer from normal tissue.

Honokiol and triphenylmethanes are small molecules with anti-tumor properties. Recently, we synthesized new honokiol analogues (HAs) that possess common features of both groups. We assessed the anti-tumor effectiveness of HAs in B-cell leukemia/lymphoma cells, namely in chronic lymphocytic leukemia (CLL) cells ex vivo and in pre-B-cell acute lymphoblastic leukemia (Nalm-6), Burkitt lymphoma (BL; Raji), diffuse large B-cell lymphoma (DLBCL; Toledo) and multiple myeloma (MM; RPMI 8226) cell lines. Four of these compounds appeared to be significantly active against the majority of cells examined, with no significant impact on healthy lymphocytes. These active HAs induced caspase-dependent apoptosis, causing significant deregulation of several apoptosis-regulating proteins. Overall, these compounds downregulated Bcl-2 and XIAP and upregulated Bax, Bak and survivin proteins. In conclusion, some of the HAs are potent tumor-selective inducers of apoptosis in ex vivo CLL and in BL, DLBCL and MM cells in vitro. Further preclinical studies of these agents are recommended.

Hepatocellular carcinoma (HCC) is the third leading cause of death in cancer patients worldwide. Understanding the molecular pathogenesis of HCC recurrence and chemoresistance is key to improving patients' prognosis. In this study, we report that downregulation of ASPP2, a member of the ankyrin-repeat-containing, SH3-domain-containing, and proline-rich-region-containing protein (ASPP) family, bestowed HCC cells with stem-like properties and resistance to chemotherapy, including the expansion of side population fractions, formation of hepatospheroids, expression of stem cell-associated genes, loss of chemosensitivity, and increased tumorigenicity in immunodeficient mice. An expression profiling assay revealed that ASPP2 specifically repressed focal adhesion kinase (FAK)/Src/extracellular signal regulated kinase (ERK) signaling. ASPP2 does this by physically interacting with C-terminal Src kinase (CSK) and stimulating its kinase activity, which eventually leads to activator protein 1 (AP1)-mediated downregulation of Snail expression. In addition, pharmacologic inhibition of Src attenuated the effects of ASPP2 deficiency. Our findings present functional and mechanistic insight into the critical role of ASPP2 in the inhibition of HCC stemness and drug resistance and may provide a new strategy for therapeutic combinations to treat HCC.

Understanding the complex interaction between growth factor and steroid hormone signaling pathways in breast cancer is key to identifying suitable therapeutic strategies to avoid progression and therapy resistance. The interaction between these two pathways is of paramount importance for the development of endocrine resistance. Nevertheless, the molecular mechanisms behind their crosstalk are still largely obscure. We previously reported that Memo is a small redox-active protein that controls heregulin-mediated migration of breast cancer cells. Here we report that Memo sits at the intersection between heregulin and estrogen signaling, and that Memo controls Estrogen Receptor alpha (ERα) sub-cellular localization, phosphorylation, and function downstream of heregulin and estrogen in breast cancer cells. Memo facilitates ERα and c-Src interaction, ERα Y537 phosphorylation, and has the ability to control ERα extra-nuclear localization. Thus, we identify Memo as an important key mediator between the heregulin and estrogen signaling pathways, which affects both breast cancer cell migration and proliferation.

Connexin43 (Cx43), the major protein forming gap junctions in astrocytes, is reduced in high-grade gliomas, where its ectopic expression exerts important effects, including the inhibition of the proto-oncogene tyrosine-protein kinase Src (c-Src). In this work we aimed to investigate the mechanism responsible for this effect. The inhibition of c-Src requires phosphorylation at tyrosine 527 mediated by C-terminal Src kinase (Csk) and dephosphorylation at tyrosine 416 mediated by phosphatases, such as phosphatase and tensin homolog (PTEN). Our results showed that the antiproliferative effect of Cx43 is reduced when Csk and PTEN are silenced in glioma cells, suggesting the involvement of both enzymes. Confocal microscopy and immunoprecipitation assays confirmed that Cx43, in addition to c-Src, binds to PTEN and Csk in glioma cells transfected with Cx43 and in astrocytes. Pull-down assays showed that region 266-283 in Cx43 is sufficient to recruit c-Src, PTEN and Csk and to inhibit the oncogenic activity of c-Src. As a result of c-Src inhibition, PTEN was increased with subsequent inactivation of Akt and reduction of proliferation of human glioblastoma stem cells. We conclude that the recruitment of Csk and PTEN to the region between residues 266 and 283 within the C-terminus of Cx43 leads to c-Src inhibition.

Neuroblastoma (NB) is the most common extracranial pediatric solid tumor with high mortality rates. The tyrosine kinase c-Src has been known to play an important role in differentiation of NB cells, but the mechanism of c-Src regulation has not been defined. Here, we characterize PAG1 (Cbp, Csk binding protein), a central inhibitor of c-Src and other Src family kinases, as a novel tumor suppressor in NB. Clinical cohort analysis demonstrate that low expression of PAG1 is a significant prognostic factor for high stage disease, increased relapse, and worse overall survival for children with NB. PAG1 knockdown in NB cells promotes proliferation and anchorage-independent colony formation with increased activation of AKT and ERK downstream of c-Src, while PAG1 overexpression significantly rescues these effects. In vivo, PAG1 overexpression significantly inhibits NB tumorigenicity in an orthotopic xenograft model. Our results establish PAG1 as a potent tumor suppressor in NB by inhibiting c-Src and downstream effector pathways. Thus, reactivation of PAG1 and inhibition of c-Src kinase activity represents an important novel therapeutic approach for high-risk NB.

UNLABELLED: Deletions at the C-terminus of the proto-oncogene protein c-Src kinase are found in the viral oncogene protein v-Src as well as in some advanced human colon cancers. They are associated with increased kinase activity and cellular invasiveness. Here, we analyzed the mRNA expression signature of a constitutively active C-terminal mutant of c-Src, c-Src(mt), in comparison with its wild-type protein, c-Src(wt), in the human non-transformed breast epithelial cell line MCF-10A. We demonstrated previously that the mutant altered migratory and metastatic properties. Genome-wide transcriptome analysis revealed that c-Src(mt) de-regulated the expression levels of approximately 430 mRNAs whose gene products are mainly involved in the cellular processes of migration and adhesion, apoptosis and protein synthesis. 82.9% of these genes have previously been linked to cellular migration, while the others play roles in RNA transport and splicing processes, for instance. Consistent with the transcriptome data, cells expressing c-Src(mt), but not those expressing c-Src(wt), showed the capacity to metastasize into the lungs of mice in vivo. The mRNA expression profile of c-Src(mt)-expressing cells shows significant overlap with that of various primary human tumor samples, possibly reflecting elevated Src activity in some cancerous cells. Expression of c-Src(mt) led to elevated migratory potential. We used this model system to analyze the transcriptional changes associated with an invasive cellular phenotype. These genes and pathways de-regulated by c-Src(mt) may provide suitable biomarkers or targets of therapeutic approaches for metastatic cells.
DATABASE: This project was submitted to the National Center for Biotechnology Information BioProject under ID PRJNA288540. The Illumina RNA-Seq reads are available in the National Center for Biotechnology Information Sequence Read Archive under study ID SRP060008 with accession numbers SRS977414 for MCF-10A cells, SRS977717 for mock cells, SRS978053 for c-Src(wt) cells and SRS978046 for c-Src(mt) cells.