Simultaneous siRNA targeting of Src and downstream signaling molecules inhibit tumor formation and metastasis of a human model breast cancer cell line

A combined opposite targeting of p110δ PI3K and RhoA abrogates skin cancer

Malignant melanoma is the most aggressive and deadly skin cancer with an increasing incidence worldwide whereas SCC is the second most common non-melanoma human skin cancer with limited treatment options. Here we show that the development and metastasis of melanoma and SCC cancers can be blocked by a combined opposite targeting of RhoA and p110δ PI3K. We found that a targeted induction of RhoA activity into tumours by deletion of p190RhoGAP-a potent inhibitor of RhoA GTPase-in tumour cells together with adoptive macrophages transfer from δD910A/D910A mice in mice bearing tumours with active RhoA abrogated growth progression of melanoma and SCC tumours. Τhe efficacy of this combined treatment is the same in tumours lacking activating mutations in BRAF and in tumours harbouring the most frequent BRAF(V600E) mutation. Furthermore, the efficiency of this combined treatment is associated with decreased ATX expression in tumour cells and tumour stroma bypassing a positive feedback expression of ATX induced by direct ATX pharmacological inactivation. Together, our findings highlight the importance of targeting cancer cells and macrophages for skin cancer therapy, emerge a reverse link between ATX and RhoA and illustrate the benefit of p110δ PI3K inhibition as a combinatorial regimen for the treatment of skin cancers.

siRNA and targeted delivery systems in breast cancer therapy

Recently, nucleic acid drugs have been considered as promising candidates in treatment of various diseases, especially cancer. Because of developing resistance to conventional chemotherapy, use of genetic tools in cancer therapy appears inevitable. siRNA is a RNAi tool with capacity of suppressing target gene. Owing to overexpression of oncogenic factors in cancer, siRNA can be used for suppressing those pathways. This review emphasizes the function of siRNA in treatment of breast tumor. The anti-apoptotic-related genes including Bcl-2, Bcl-xL and survivin can be down-regulated by siRNA in triggering cell death in breast cancer. STAT3, STAT8, Notch1, E2F3 and NF-κB are among the factors with overexpression in breast cancer that their silencing by siRNA paves the way for impairing tumor proliferation and invasion. The oncogenic mechanisms in drug resistance development in breast tumor such as lncRNAs can be suppressed by siRNA. Furthermore, siRNA reducing P-gp activity can increase drug internalization in tumor cells. Because of siRNA degradation at bloodstream and low accumulation at tumor site, nanoplatforms have been employed for siRNA delivery to suppress breast tumor progression via improving siRNA efficacy in gene silencing. Development of biocompatible and efficient nanostructures for siRNA delivery can make milestone progress in alleviation of breast cancer patients.

Apelin Promotes Prostate Cancer Metastasis by Downregulating TIMP2 via Increases in miR-106a-5p Expression

Prostate cancer commonly affects the urinary tract of men and metastatic prostate cancer has a very low survival rate. Apelin belongs to the family of adipokines and is associated with cancer development and metastasis. However, the effects of apelin in prostate cancer metastasis is undetermined. Analysis of the database revealed a positive correlation between apelin level with the progression and metastasis of prostate cancer patients. Apelin treatment facilitates cell migration and invasion through inhibiting tissue inhibitor of metalloproteinase 2 (TIMP2) expression. The increasing miR-106a-5p synthesis via c-Src/PI3K/Akt signaling pathway is controlled in apelin-regulated TIMP2 production and cell motility. Importantly, apelin blockade inhibits prostate cancer metastasis in the orthotopic mouse model. Thus, apelin is a promising therapeutic target for curing metastatic prostate cancer.

The human amniotic epithelium confers a bias to differentiate toward the neuroectoderm lineage in human embryonic stem cells

Human embryonic stem cells (hESCs) derive from the epiblast and have pluripotent potential. To maintain the conventional conditions of the pluripotent potential in an undifferentiated state, inactivated mouse embryonic fibroblast (iMEF) is used as a feeder layer. However, it has been suggested that hESC under this conventional condition (hESC-iMEF) is an artifact that does not correspond to the in vitro counterpart of the human epiblast. Our previous studies demonstrated the use of an alternative feeder layer of human amniotic epithelial cells (hAECs) to derive and maintain hESC. We wondered if the hESC-hAEC culture could represent a different pluripotent stage than that of naïve or primed conventional conditions, simulating the stage in which the amniotic epithelium derives from the epiblast during peri-implantation. Like the conventional primed hESC-iMEF, hESC-hAEC has the same levels of expression as the ‘pluripotency core’ and does not express markers of naïve pluripotency. However, it presents a downregulation of HOX genes and genes associated with the endoderm and mesoderm, and it exhibits an increase in the expression of ectoderm lineage genes, specifically in the anterior neuroectoderm. Transcriptome analysis showed in hESC-hAEC an upregulated signature of genes coding for transcription factors involved in neural induction and forebrain development, and the ability to differentiate into a neural lineage was superior in comparison with conventional hESC-iMEF. We propose that the interaction of hESC with hAEC confers hESC a biased potential that resembles the anteriorized epiblast, which is predisposed to form the neural ectoderm.

ICAM-1 promotes cancer progression by regulating SRC activity as an adapter protein in colorectal cancer

Colorectal cancer (CRC) has a 5-year survival rate of <10%, as it can metastasize to the lungs and liver. Anticancer drugs and targeted therapies used to treat metastatic colorectal cancer have insufficient therapeutic efficacy and are associated with complications. Therefore, research to develop new targeted therapeutics is necessary. Here, we present a novel discovery that intracellular adhesion molecule-1 (ICAM-1) is a potential therapeutic target to enhance therapeutic effectiveness for CRC. ICAM-1 is an important regulator of cell-cell interactions and recent studies have shown that it promotes malignancy in several carcinomas. However, little is known about its effect on CRC. Therefore, we conducted a study to define the mechanism by which ICAM-1 acts. ICAM-1 is phosphorylated by tyrosine-protein kinase Met (c-MET), and phosphorylated ICAM-1 can interact with SRC to increase SRC activity. Consequently, ICAM-1 may further accelerate SRC signaling, promoting the malignant potential of cancer. In addition, treatment with antibodies targeting ICAM-1 showed excellent therapeutic effects in reducing metastasis and angiogenesis. These findings suggest for the first time that ICAM-1 is an important adapter protein capable of mediating the c-MET-SRC signaling axis. Therefore, ICAM-1 can be used as a novel therapeutic target and a metastatic marker for CRC.

gp130 Cytokines Activate Novel Signaling Pathways and Alter Bone Dissemination in ER+ Breast Cancer Cells

Breast cancer cells frequently home to the bone marrow, where they encounter signals that promote survival and quiescence or stimulate their proliferation. The interleukin-6 (IL-6) cytokines signal through the co-receptor glycoprotein130 (gp130) and are abundantly secreted within the bone microenvironment. Breast cancer cell expression of leukemia inhibitory factor (LIF) receptor (LIFR)/STAT3 signaling promotes tumor dormancy in the bone, but it is unclear which, if any of the cytokines that signal through LIFR, including LIF, oncostatin M (OSM), and ciliary neurotrophic factor (CNTF), promote tumor dormancy and which signaling pathways are induced. We first confirmed that LIF, OSM, and CNTF and their receptor components were expressed across a panel of breast cancer cell lines, although expression was lower in estrogen receptor-negative (ER^- ) bone metastatic clones compared with parental cell lines. In estrogen receptor-positive (ER⁺ ) cells, OSM robustly stimulated phosphorylation of known gp130 signaling targets STAT3, ERK, and AKT, while CNTF activated STAT3 signaling. In ER^- breast cancer cells, OSM alone stimulated AKT and ERK signaling. Overexpression of OSM, but not CNTF, reduced dormancy gene expression and increased ER⁺ breast cancer bone dissemination. Reverse-phase protein array revealed distinct and overlapping pathways stimulated by OSM, LIF, and CNTF with known roles in breast cancer progression and metastasis. In breast cancer patients, downregulation of the cytokines or receptors was associated with reduced relapse-free survival, but OSM was significantly elevated in patients with invasive disease and distant metastasis. Together these data indicate that the gp130 cytokines induce multiple signaling cascades in breast cancer cells, with a potential pro-tumorigenic role for OSM and pro-dormancy role for CNTF. © 2021 American Society for Bone and Mineral Research (ASBMR).

Anti-progranulin/GP88 antibody AG01 inhibits triple negative breast cancer cell proliferation and migration

BACKGROUND

Triple negative breast cancer (TNBC) is characterized by invasiveness and short survival. Identifying novel TNBC-targeted therapies, to potentiate standard of care (SOC) therapy, is an unmet need. Progranulin (PGRN/GP88) is a biological driver of tumorigenesis, survival, and drug resistance in several cancers including breast cancer (BC). PGRN/GP88 tissue expression is an independent prognostic factor of recurrence while elevated serum PGRN/GP88 level is associated with poor outcomes. Since PGRN/GP88 expression is elevated in 30% TNBC, we investigated the involvement of progranulin on TNBC.

METHODS

The effect of inhibiting PGRN/GP88 expression in TNBC cells by siRNA was investigated. The effects of a neutralizing anti-human PGRN/GP88 monoclonal antibody AG01 on the proliferation and migration of two TNBC cell lines expressing PGRN/GP88 were then examined in vitro and in vivo.

RESULTS

Inhibition of GP88 expression by siRNA and AG01 treatment to block PGRN/GP88 action reduced proliferation and migration in a dose-dependent fashion in MDA-MB-231 and HS578-T cells. Western blot analysis showed decreased expression of phosphorylated protein kinases p-Src, p-AKT, and p-ERK upon AG01 treatment, as well as inhibition of tumor growth and Ki67 expression in vivo.

CONCLUSION

PGRN/GP88 represents a therapeutic target with companion diagnostics. Blocking PGRN/GP88 with antibody treatment may provide novel-targeted solutions in TNBC treatment which could eventually address the issue of toxicity and unresponsiveness associated with SOC.

The role of tumor suppressor short non-coding RNAs on breast cancer

Characterized by remarkable levels of aggression and malignancy, BC remains one of the leading causes of death in females world wide. Accordingly, significant efforts have been made to develop early diagnostic tools, increase treatment efficacy, and improve patient prognosis. Hopefully, many of the molecular mechanisms underlying BC have been detected and show promising targeting potential. In particular, short and long non-coding RNAs (ncRNAs) are a class of endogenous BC controllers and include a number of different species including microRNAs, Piwi-interacting RNAs, small nucleolar RNA, short interfering RNAs, and tRNA-derivatives. In this review, we discuss the tumor suppressing roles of ncRNAs in the context of BC, and the mechanisms by which ncRNAs target tumor hallmarks, including apoptosis, proliferation, invasion, metastasis, epithelial-mesenchymal transition, angiogenesis, and cell cycle progression, in addition to their diagnostic and prognostic significance in cancer treatment.

The Anti-Cancer Effect of Linusorb B3 from Flaxseed Oil through the Promotion of Apoptosis, Inhibition of Actin Polymerization, and Suppression of Src Activity in Glioblastoma Cells

Linusorbs (LOs) are natural peptides found in flaxseed oil that exert various biological activities. Of LOs, LOB3 ([1–9-NαC]-linusorb B3) was reported to have antioxidative and anti-inflammatory activities; however, its anti-cancer activity has been poorly understood. Therefore, this study investigated the anti-cancer effect of LOB3 and its underlying mechanism in glioblastoma cells. LOB3 induced apoptosis and suppressed the proliferation of C6 cells by inhibiting the expression of anti-apoptotic genes, B cell lymphoma 2 (Bcl-2) and p53, as well as promoting the activation of pro-apoptotic caspases, caspase-3 and -9. LOB3 also retarded the migration of C6 cells, which was achieved by suppressing the formation of the actin cytoskeleton critical for the progression, invasion, and metastasis of cancer. Moreover, LOB3 inhibited the activation of the proto-oncogene, Src, and the downstream effector, signal transducer and activator of transcription 3 (STAT3), in C6 cells. Taken together, these results suggest that LOB3 plays an anti-cancer role by inducing apoptosis and inhibiting the migration of C6 cells through the regulation of apoptosis-related molecules, actin polymerization, and proto-oncogenes.

Src inhibition attenuates polyglutamine-mediated neuromuscular degeneration in spinal and bulbar muscular atrophy

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by an expanded CAG repeat in the androgen receptor (AR) gene. Here, we perform a comprehensive analysis of signaling pathways in a mouse model of SBMA (AR-97Q mice) utilizing a phosphoprotein assay. We measure the levels of 17 phosphorylated proteins in spinal cord and skeletal muscle of AR-97Q mice at three stages. The level of phosphorylated Src (p-Src) is markedly increased in the spinal cords and skeletal muscles of AR-97Q mice prior to the onset. Intraperitoneal administration of a Src kinase inhibitor improves the behavioral and histopathological phenotypes of the transgenic mice. We identify p130Cas as an effector molecule of Src and show that the phosphorylated p130Cas is elevated in murine and cellular models of SBMA. These results suggest that Src kinase inhibition is a potential therapy for SBMA.

Selective Proteolysis to Study the Global Conformation and Regulatory Mechanisms of c-Src Kinase

Protein kinase pathways are traditionally mapped by monitoring downstream phosphorylation. Meanwhile, the noncatalytic functions of protein kinases remain under-appreciated as critical components of kinase signaling. c-Src is a protein kinase known to have noncatalytic signaling function important in healthy and disease cell signaling. Large conformational changes in the regulatory domains regulate c-Src's noncatalytic functions. Herein, we demonstrate that changes in the global conformation of c-Src can be monitored using a selective proteolysis methodology. Further, we use this methodology to investigate changes in the global conformation of several clinical and nonclinical mutations of c-Src. Significantly, we identify a novel activating mutation observed clinically, W121R, that can escape down-regulation mechanisms. Our methodology can be expanded to monitor the global conformation of other tyrosine kinases, including c-Abl, and represents an important tool toward the elucidation of the noncatalytic functions of protein kinases.

Synergistic Anti-Cancer Effects of AKT and SRC Inhibition in Human Pancreatic Cancer Cells

PURPOSE

To investigate the effect of combined inhibition of protein kinase B (AKT) and SRC on the growth and metastatic potential of human pancreatic cancer cells.

MATERIALS AND METHODS

AKT and SRC were inhibited using 10-DEBC and PP2, respectively. The expression of their messenger RNAs were down-regulated by specific small interfering RNA (siRNA). Changes in pancreatic cancer cell growth and metastatic potential were determined using a cell viability assay and a xenotransplant model of pancreatic cancer, as well as cell migration and invasion assays. Signal proteins were analyzed by Western blot.

RESULTS

The inhibitors 10-DEBC and PP2 suppressed cell proliferation in a dose-dependent fashion in pancreatic cancer cell lines MIA PaCa-2 and PANC-1. The simultaneous inhibition of AKT and SRC at low concentrations resulted in a significant suppression of cell proliferation. Knockdown of AKT2 and SRC using siRNAs also significantly decreased cell proliferation. In a pancreatic cancer model, combined treatment with 10-DEBC and PP2 also significantly suppressed the growth of pancreatic cancer. Application of 10-DEBC with PP2 significantly reduced the metastatic potential of pancreatic cancer cells by inhibiting migration and invasion. The combined inhibition suppressed the phosphorylation of mTOR and ERK in pancreatic cancer cells.

CONCLUSION

Combined targeting of AKT and SRC resulted in a synergistic efficacy against human pancreatic cancer growth and metastasis.

"Do We Know Jack" About JAK? A Closer Look at JAK/STAT Signaling Pathway

Janus tyrosine kinase (JAK) family of proteins have been identified as crucial proteins in signal transduction initiated by a wide range of membrane receptors. Among the proteins in this family JAK2 has been associated with important downstream proteins, including signal transducers and activators of transcription (STATs), which in turn regulate the expression of a variety of proteins involved in induction or prevention of apoptosis. Therefore, the JAK/STAT signaling axis plays a major role in the proliferation and survival of different cancer cells, and may even be involved in resistance mechanisms against molecularly targeted drugs. Despite extensive research focused on the protein structure and mechanisms of activation of JAKs, and signal transduction through these proteins, their importance in cancer initiation and progression seem to be underestimated. This manuscript is an attempt to highlight the role of JAK proteins in cancer biology, the most recent developments in targeting JAKs, and the central role they play in intracellular cross-talks with other signaling cascades.

Src Plays an Important Role in AGE-Induced Endothelial Cell Proliferation, Migration, and Tubulogenesis

Advanced glycation end products (AGEs), produced by the non-enzymatic glycation of proteins and lipids under hyperglycemia or oxidative stress conditions, has been implicated to be pivotal in the development of diabetic vascular complications, including diabetic retinopathy. We previously demonstrated that Src kinase played a causative role in AGE-induced hyper-permeability and barrier dysfunction in human umbilical vein endothelial cells (HUVECs). While the increase of vascular permeability is the early event of angiogenesis, the effect of Src in AGE-induced angiogenesis and the mechanism has not been completely revealed. Here, we investigated the impact of Src on AGE-induced HUVECs proliferation, migration, and tubulogenesis. Inhibition of Src with inhibitor PP2 or siRNA decreased AGE-induced migration and tubulogenesis of HUVECs. The inactivation of Src with pcDNA3/flag-Src^K298M also restrained AGE-induced HUVECs proliferation, migration, and tube formation, while the activation of Src with pcDNA3/flag-Src^Y530F enhanced HUVECs angiogenesis alone and exacerbated AGE-induced angiogenesis. AGE-enhanced HUVECs angiogenesis in vitro was accompanied with the phosphorylation of ERK in HUVECs. The inhibition of ERK with its inhibitor PD98059 decreased AGE-induced HUVECs angiogenesis. Furthermore, the inhibition and silencing of Src suppressed the AGE-induced ERK activation. And the silencing of AGEs receptor (RAGE) inhibited the AGE-induced ERK activation and angiogenesis as well. In conclusions, this study demonstrated that Src plays a pivotal role in AGE-promoted HUVECs angiogenesis by phosphorylating ERK, and very likely through RAGE-Src-ERK pathway.

c-Src inhibitor selectively inhibits triple-negative breast cancer overexpressed Vimentin in vitro and in vivo

Oncogene c‐Src has been found to be a potential target for the treatment of triple‐negative breast cancer (TNBC). However, the therapeutic effects of the c‐Src inhibitor on TNBC patients are controversial compared to those on cell lines. The molecular mechanisms of the inhibitory effects of the c‐Src inhibitor on TNBC remain unclear. Herein, we showed that a specific c‐Src inhibitor, PP2, was effective in inhibiting phosphorylation of c‐Src in 4 cell lines: T‐47D, SK‐BR‐3, SUM1315MO2, and MDA‐MB‐231, regardless of hormone receptors and human epidermal growth factor receptor 2 (HER2) expression levels. Giving PP2 preferentially reduced the S phase of cell cycles and inhibited colony formation in SUM1315MO2 and MDA‐MB‐231, but not in SK‐BR‐3 and T‐47D cells. Furthermore, PP2 effectively blocked cell migration/invasion and epithelial‐mesenchymal transition (EMT) in TNBC cell lines, SUM1315MO2 and MDA‐MB‐231. An EMT biomarker, vimentin, was highly expressed in 2 TNBC cell lines when they were compared with SK‐BR‐3 and T‐47D cells. Further depletion of vimentin by shRNA remarkably attenuated the inhibitory effects of the c‐Src inhibitor on TNBC cells in vitro and in vivo, indicating a crucial action of vimentin to affect the function of c‐Src in TNBC. This study provides an important rationale for the clinic to precisely select TNBC patients who would benefit from c‐Src inhibitor treatment. This finding suggests that traditional markers for TNBC are not sufficient to precisely define this aggressive type of cancer. Vimentin is identified as an important biomarker to enable categorization of TNBC.

Delivery of gene targeting siRNAs to breast cancer cells using a multifunctional peptide complex that promotes both targeted delivery and endosomal release

RNA interference has been used to dissect the importance of individual gene products in various human disease processes, including cancer. Small-interfering RNA, or siRNA, is one of the tools utilized in this regard, but specially-designed delivery agents are required to allow the siRNA to gain optimal access to the cell interior. Our laboratory has utilized two different siRNA-binding delivery peptides containing a polyarginine core, and modified by myristoylation and targeting motifs (iRGD or Lyp-1). A third peptide was designed to assist with endosomal release. Various ratios of the peptides and siRNA were combined and assayed for the ability to form stable complexes, and optimized ratios were determined. The complexes were found to form particles, with the majority having a diameter of 100-300 nm, as visualized by electron microscopy. These siRNA complexes have enhanced protection from nucleases present in serum, as compared to "naked" unprotected siRNA. The particles were internalized by the cells and could be detected in the cell cytoplasm by confocal fluorescence microscopy. In functional assays, peptide/siRNA complexes were shown to cause the knock down of corresponding targeted proteins. The peptide with the LyP-1 targeting motif was more effective at knockdown in MDA-MB-231 breast cancer cells than the peptide with the iRGD motif. Inclusion of the endosomal release peptide in the complexes greatly enhanced the peptide/siRNA effects. Peptide/siRNA complexes simultaneously targeting Stat3 and c-Myc caused a marked reduction in anchorage-independent growth, a property correlated with tumorigenicity. This study demonstrates the ability of a peptide-based siRNA-delivery system to deliver siRNA into breast cancer cells and cause both protein knockdown and suppression of the malignant phenotype. Such peptide complexes are likely to become highly useful siRNA-delivery vehicles for the characterization, and potentially for the treatment, of human cancer.

Inhibition of glycogen synthase kinase-3 beta induces apoptosis and mitotic catastrophe by disrupting centrosome regulation in cancer cells

Glycogen synthase kinase-3 beta (GSK-3β) has been investigated as a therapeutic target for numerous human diseases including cancer because of their diverse cellular functions. Although GSK-3β inhibitors have been investigated as anticancer reagents, precise biological mechanisms remain to be determined. In this study, we investigated the anticancer effects of GSK-3β inhibitors on cancer cell lines and observed centrosome dysregulation which resulted in abnormal mitosis. Mitotic checkpoints sensed the mitotic abnormalities and induced apoptosis. For cells that were inherently resistant to apoptosis, cell death distinct from apoptosis was induced. After GSK-3β inhibitor treatment, these cells exhibited characteristic features of mitotic catastrophe, including distended and multivesiculated nuclei and inappropriate reductions in cyclin B1 expression. This suggested that mitotic catastrophe was an alternative mechanism in cells resistant to apoptosis. Although the role of GSK-3β in centrosomes has not yet been clarified, phosphorylated GSK-3β was localised in centrosomes. From these data, GSK-3β seems to regulate centrosome function. Thus, we propose that centrosome dysregulation is an important mechanism for the anticancer effects of GSK-3β inhibitors and that mitotic catastrophe serves as a safe-guard system to remove cells with any mitotic abnormalities induced by GSK-3β inhibition.

CD44 regulates cell proliferation, migration, and invasion via modulation of c-Src transcription in human breast cancer cells

CD44 was recently identified as a cancer initiation marker on the cell membrane. The cytoplasmic tail of CD44 is known to bind ERM (ezrin, radixin, moesin) proteins, cytoskeletal proteins like ankyrin, and the non-receptor tyrosine kinase c-Src. CD44 transmits its oncogenic signaling via c-Src and its downstream effectors. To investigate the role of CD44 in breast cancer cells, we generated CD44 knock-down cells via retroviral delivery of shRNA against CD44. We found that silencing of CD44 decreased the proliferation, migration, and invasion of breast cancer cells. The expression and activity of cell migration-related proteins, including c-Src, paxillin, and FAK were decreased by CD44 silencing. We also found that the c-Jun protein level was negatively regulated via induction of a GSK-3β-dependent degradation pathway in CD44 knock-down cells. The expression level of Sp1, a target gene product of c-Jun, was also decreased in these cells. Finally, CD44 knock-down suppressed both mRNA and protein levels of c-Src and its downstream MAPK pathway as a result of down-regulation of Sp1 as a transcription factor for c-Src. Collectively, these results indicate that biological changes induced by CD44 silencing are mediated by cumulative down-regulation of c-Jun, Sp1, and c-Src in human breast cancer cells.

A novel biphenyl urea derivate inhibits the invasion of breast cancer through the modulation of CXCR4

The increased migration and invasion of breast carcinoma cells are key events in the development of metastasis to the lymph nodes and distant organs. CXCR4, the receptor for stromal-derived factor-1, is reportedly involved in breast carcinogenesis and invasion. In this study, we investigated a novel biphenyl urea derivate, TPD7 for its ability to affect CXCR4 expression as well as function in breast cancer cells. We demonstrated that TPD7 inhibited the breast cancer proliferation and down-regulated the CXCR4 expression on breast cancer cells both over-expressing and low-expressing HER2, an oncogene known to induce the chemokine receptor. Treatments with pharmacological proteasome inhibitors partial suppressed TPD7-induced decrease in CXCR4 expression. Real-time PCR analysis revealed that down-regulation of CXCR4 by TPD7 also occurred at the translational level. Inhibition of CXCR4 expression by TPD7 further correlated with the suppression of SDF-1α-induced migration and invasion in breast tumour cells, knockdown of CXCR4 attenuated TPD7-inhibitory effects. In addition, TPD7 treatment significantly suppressed matrix metalloproteinase (MMP)-2 and MMP-9 expression, the downstream targets of CXCR4, perhaps via inactivation of the ERK signaling pathway. Overall, our results showed that TPD7 exerted its anti-invasive effect through the down-regulation of CXCR4 expression and thus had the potential for the treatment of breast cancer.

Role of Kinase Epidermal Growth Factor Receptor and SRC in the Caerulein-Induced Acute Pancreatitis in Mice

OBJECTIVES

In this study, we identified the protein kinases that play the most distinct roles in the occurrence of acute pancreatitis (AP).

METHODS

Gene expression profile data were downloaded from Gene Expression Omnibus database (GSE3644). The sample was from caerulein-induced AP mice. The intersection of the differentially expressed genes in AP mice taken from a protein kinase database was obtained for screening of the protein kinase encoded genes that were differentially expressed. Database for annotation, visualization, and integrated discovery was used for the functional enrichment analysis. Kinase inhibitors that regulated these kinases were retrieved from PubMed through text mining.

RESULTS

Twenty-nine differentially expressed kinase encoded genes were identified through screening. The functional enrichment analysis demonstrated that the functions of these genes were primarily enriched in "mitogen-activated protein kinase signaling pathway," followed by "extracellular regulated protein kinases pathway," "neurotrophin signaling pathway," "adherens junction," and "gap junction." SRC and epidermal growth factor receptor (EGFR) were related to extracellular regulated protein kinases pathway and also related to adherens junction as well as gap junction. On the basis of the regulated kinases, the kinase inhibitors reported in the literature were classified into multiple groups.

CONCLUSIONS

EGFR and SRC may be coexpressed in AP. The kinase inhibitors working together in SRC and EGFR may play better efficacy in the treatment of AP.

Trefoil factor 3 promotes metastatic seeding and predicts poor survival outcome of patients with mammary carcinoma

Introduction

Recurrence or early metastasis remains the predominant cause of mortality in patients with estrogen receptor positive (ER+) mammary carcinoma (MC). However, the molecular mechanisms underlying the initial progression of ER+ MC to metastasis remains poorly understood. Trefoil factor 3 (TFF3) is an estrogen-responsive oncogene in MC. Herein, we provide evidence for a functional role of TFF3 in metastatic progression of ER+ MC.

Methods

The association of TFF3 expression with clinicopathological parameters and survival outcome in a cohort of MC patients was assessed by immunohistochemistry. The expression of TFF3 in MCF7 and T47D cells was modulated by forced expression or siRNA-mediated depletion of TFF3. mRNA and protein levels were determined using qPCR and western blot. The functional effect of modulation of TFF3 expression in MC cells was determined in vitro and in vivo. Mechanistic analyses were performed using reporter constructs, modulation of signal transducer and activator of transcription 3 (STAT3) expression, and pharmacological inhibitors against c-SRC and STAT3 activity.

Results

TFF3 protein expression was positively associated with larger tumour size, lymph node metastasis, higher stage, and poor survival outcome. Forced expression of TFF3 in ER+ MC cells stimulated colony scattering, cell adhesion to a Collagen I-coated matrix, colony formation on a Collagen I- or Matrigel-coated matrix, endothelial cell adhesion, and transmigration through an endothelial cell barrier. In vivo, forced expression of TFF3 in MCF7 cells stimulated the formation of metastatic nodules in animal lungs. TFF3 regulation of the mRNA levels of epithelial, mesenchymal, and metastatic-related genes in ER+ MC cells were consistent with the altered cell behaviour. Forced expression of TFF3 in ER+ MC cells stimulated phosphorylation of c-SRC that subsequently increased STAT3 activity, which lead to the downregulation of E-cadherin. siRNA-mediated depletion of TFF3 reduced the invasiveness of ER+ MC cells.

Conclusions

TFF3 expression predicts metastasis and poor survival outcome of patients with MC and functionally stimulates cellular invasion and metastasis of ER+ MC cells. Adjuvant functional inhibition of TFF3 may therefore be considered to ameliorate outcome of ER+ MC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0429-3) contains supplementary material, which is available to authorized users.

Oncogene dependency and the potential of targeted RNAi-based anti-cancer therapy

Cancers arise through the progression of multiple genetic and epigenetic defects that lead to deregulation of numerous signalling networks. However, the last decade has seen the development of the concept of 'oncogene addiction', where tumours appear to depend on a single oncogene for survival. RNAi has provided an invaluable tool in the identification of these oncogenes and oncogene-dependent cancers, and also presents great potential as a novel therapeutic strategy against them. Although RNAi therapeutics have demonstrated effective killing of oncogene-dependent cancers in vitro, their efficacy in vivo is severely limited by effective delivery systems. Several virus-based RNAi delivery strategies have been explored, but problems arose associated with high immunogenicity, random genome integration and non-specific targeting. This has directed efforts towards non-viral formulations, including delivery systems based on virus-like particles, liposomes and cationic polymers, which can circumvent some of these problems by immunomasking and the use of specific tumour-targeting ligands. This review outlines the prevalence of oncogene-dependent cancers, evaluates the potential of RNAi-based therapeutics and assesses the relative strengths and weaknesses of different approaches to targeted RNAi delivery.

The inhibition of SRC family kinase suppresses pancreatic cancer cell proliferation, migration, and invasion

OBJECTIVES

Src is considered a rising therapeutic target for the treatment of solid tumors, and Src family kinases (SFKs) participate in cancer cell proliferation and survival. The role of SFK suppression was investigated in the proliferation, migration, and invasion of pancreatic cancer cells.

METHODS

Knockdown of the SFKs in pancreatic cancer cells was achieved by transfecting small interfering RNAs, and its effects were investigated using proliferation, wound, and invasion assays.

RESULTS

The SFK inhibitors suppressed proliferation and induced cell cycle arrest in pancreatic cancer cells. The SFK messenger RNA profiles showed that Yes1, Lyn, Fyn, Frk, Hck, and Src were expressed. Specific small interfering RNA transfection suppressed the messenger RNA expressions of Yes1, Lyn, Fyn, Frk, and Src, and the knockdown suppressed cell proliferation by 16.7% to 47.3% in PANC-1 cells. Knockdown of any of these 5 SFKs suppressed proliferation in other pancreatic cancer cell lines by 3.0% to 40.5%. The knockdowns significantly reduced pancreatic cancer cell migration by 24.9% to 66.7% and completely inhibited invasion.

CONCLUSIONS

These results suggest that the knockdown of Yes1, Lyn, Fyn, Frk, or Src reduce human pancreatic cancer cell proliferation, migration, and invasion, and that SFKs should be viewed as critical therapeutic targets of pancreatic cancer.

Triple combination of siRNAs targeting TGFβ1, TGFβR2, and CTGF enhances reduction of collagen I and smooth muscle actin in corneal fibroblasts

PURPOSE

Transforming growth factor β1 (TGFβ1), TGFβ receptor (TGFβR2), and connective tissue growth factor (CTGF) are key regulators of fibrosis in the cornea and in other tissues, including liver, skin, and kidney. We developed an antifibrotic treatment targeting these three critical scarring genes by using a combination of small interfering RNAs (siRNAs) and assessed its effect on downstream scarring genes, collagen I, and α smooth muscle actin (SMA).

METHODS

Up to six individual siRNAs for each of the three target gene mRNAs were transfected into cultures of rabbit corneal fibroblasts at concentrations from 15 to 90 nM. The knockdown of target gene proteins was measured by ELISA, and the two most effective siRNAs were tested in dual combinations. Knockdown percentages of both individual and dual siRNA combinations were analyzed for synergy by using combination index to predict "effective" and "ineffective" triple siRNA combinations. Effects of both triple siRNA combinations on target and downstream mRNAs were measured by using quantitative RT-PCR, and levels of SMA protein were assessed by immunohistochemistry.

RESULTS

Single and dual siRNA combinations produced a wide range of protein knockdown of target genes (5%-80%). The effective triple siRNA combination significantly reduced mRNA levels of target genes (>80%) and downstream scarring genes (>85%), and of SMA protein (>95%), and significantly reduced cell migration without reducing cell viability.

CONCLUSIONS

Simultaneous targeting of TGFβ1, TGFβR2, and CTGF genes by effective triple siRNA combination produced high knockdown of target and downstream scarring genes without cell toxicity, which may have clinical applications in reducing corneal fibrosis and scarring in other tissues.

Protein tyrosine phosphatases as novel targets in breast cancer therapy

Breast cancer is linked to hyperactivation of protein tyrosine kinases (PTKs), and recent studies have unveiled that selective tyrosine dephosphorylation by protein tyrosine phosphatases (PTPs) of specific substrates, including PTKs, may activate or inactivate oncogenic pathways in human breast cancer cell growth-related processes. Here, we review the current knowledge on the involvement of PTPs in breast cancer, as major regulators of breast cancer therapy-targeted PTKs, such as HER1/EGFR, HER2/Neu, and Src. The functional interplay between PTKs and PTK-activating or -inactivating PTPs, and its implications in novel breast cancer therapies based on targeting of specific PTPs, are discussed.

miR-124 inhibits STAT3 signaling to enhance T cell-mediated immune clearance of glioma

miRNAs (miR) have been shown to modulate critical gene transcripts involved in tumorigenesis, but their role in tumor-mediated immunosuppression is largely unknown. On the basis of miRNA gene expression in gliomas using tissue microarrays, in situ hybridization, and molecular modeling, miR-124 was identified as a lead candidate for modulating STAT3 signaling, a key pathway mediating immunosuppression in the tumor microenvironment. miR-124 is absent in all grades and pathologic types of gliomas. Upon upregulating miR-124 in glioma cancer stem cells (gCSC), the STAT3 pathway was inhibited, and miR-124 reversed gCSC-mediated immunosuppression of T-cell proliferation and induction of forkhead box P3 (Foxp3)(+) regulatory T cells (Treg). Treatment of T cells from immunosuppressed glioblastoma patients with miR-124 induced marked effector response including upregulation of interleukin (IL)-2, IFN-γ, and TNF-α. Both systemic administration of miR-124 or adoptive miR-124-transfected T-cell transfers exerted potent anti-glioma therapeutic effects in clonotypic and genetically engineered murine models of glioblastoma and enhanced effector responses in the local tumor microenvironment. These therapeutic effects were ablated in both CD4(+)- and CD8(+)-depleted mice and nude mouse systems, indicating that the therapeutic effect of miR-124 depends on the presence of a T-cell-mediated antitumor immune response. Our findings highlight the potential application of miR-124 as a novel immunotherapeutic agent for neoplasms and serve as a model for identifying miRNAs that can be exploited as immunotherapeutics.

Simultaneous suppression of Src and signal transducer and activator of transcription 3 inhibits the growth of epithelial ovarian cancer cells

OBJECTIVE

The reciprocal regulation of c-Src and STAT3 activation seems to be associated with the poor response to c-Src inhibitors of ovarian cancer. This study aims to investigate inhibition of cell proliferation and enhancement of the cytotoxic effect of chemotherapeutic agents via simultaneous suppression of c-Src and STAT3 in ovarian cancer cell lines.

STUDY DESIGN

Specific siRNAs targeting c-Src and STAT3 were produced and transfected into an SKOV3 ovarian cancer cell line. We confirmed the downregulation of c-Src and STAT3 mRNAs by reverse transcriptase polymerase chain reaction. MTT assay was used to assess cytotoxicity following cisplatin administration. Protein expression level was evaluated by Western blot.

RESULTS

Cell growth was significantly inhibited by c-Src or STAT3 siRNA. Cytotoxicity was not increased in cisplatin-treated SKOV3 by c-Src siRNA only or STAT3 siRNA only, but cell viability was decreased significantly in cisplatin-treated cells after simultaneous transfection with c-Src and STAT3 siRNAs. Specifically, the viability was significantly decreased from 30% to 55% within the IC50 concentration following simultaneous transfection with c-Src and STAT3 siRNAs, particularly after 72 h. Src and survivin protein expression level was significantly decreased at 72 h after transfection of c-Src and STAT3 siRNAs.

CONCLUSIONS

This study has demonstrated the principle that the simultaneous suppression of c-Src and STAT3 inhibits the growth of epithelial ovarian cancer cells and seems to enhance the cytotoxicity of chemotherapeutic agents in ovarian cancer.

Reversine induces cell cycle arrest, polyploidy, and apoptosis in human breast cancer cells

BACKGROUND

Reversine, a small synthetic purine analogue, has been reported to be effective in tumor suppression. In the present study, we demonstrated an antitumor activity of reversine that could suppress cellular proliferation and induce cell cycle arrest and apoptosis in human breast cancer cell lines.

METHODS

To evaluate whether reversine could suppress cell growth of MCF-7 and MDA-MB-231 cells and induce cell death, the cell viability, cell cycle, and apoptosis were determined in this study.

RESULTS

Reversine treatment in human breast cancer cells reduced cell viability in a dose-dependent manner. Cell cycle accumulation at the G2/M phase in reversine-treated cells was also determined. Moreover, polyploidy was also found in reversine-treated cells. Apoptosis in reversine-treated cells was exhibited with PARP cleavage and caspase-3 and caspase-8 activation, but not caspase-9 activation, indicating that caspase-dependent apoptosis mediated by an extrinsic pathway took place in reversine-treated cells. Furthermore, reversine attenuated cell death in cells pretreated with a pan-caspase inhibitor before reversine treatment.

CONCLUSIONS

In the present study, we demonstrated that reversine contributes to growth inhibition in human breast cancer cells through cell cycle arrest, polyploidy, and/or apoptosis induction. The apoptosis mediated by reversine was induced by the mitochondria-independent pathway. Therefore, the potential role of reversine as a novel therapeutic agent for the treatment of breast cancer is worthy of further investigation.

Establishment of a human lung cancer cell line with high metastatic potential to multiple organs: gene expression associated with metastatic potential in human lung cancer

Convenient and reliable multiple organ metastasis model systems might contribute to understanding the mechanism(s) of metastasis of lung cancer, which may lead to overcoming metastasis and improvement in the treatment outcome of lung cancer. We isolated a highly metastatic subline, PC14HM, from the human pulmonary adenocarcinoma cell line, PC14, using an in vivo selection method. The expression of 34,580 genes was compared between PC14HM and parental PC14 by cDNA microarray analysis. Among the differentially expressed genes, expression of four genes in human lung cancer tissues and adjacent normal lung tissues were compared using real-time reverse transcription polymerase chain reaction. Although BALB/c nude mice inoculated with parental PC14 cells had few metastases, almost all mice inoculated with PC14HM cells developed metastases in multiple organs, including the lung, bone and adrenal gland, the same progression seen in human lung cancer. cDNA microarray analysis revealed that 981 genes were differentially (more than 3-fold) expressed between the two cell lines. Functional classification revealed that many of those genes were associated with cell growth, cell communication, development and transcription. Expression of three upregulated genes (HRB-2, HS3ST3A1 and RAB7) was higher in human cancer tissue compared to normal lung tissue, while expression of EDG1, which was downregulated, was lower in the cancer tissue compared to the normal lung. These results suggest that the newly established PC14HM cell line may provide a mouse model of widespread metastasis of lung cancer. This model system may provide insights into the key genetic determinants of widespread metastasis of lung cancer.

Traditional Chinese medicine as dual guardians against hypertension and cancer?

This study utilizes the comprehensive traditional Chinese medicine database TCM Database@Taiwan ( http://tcm.cmu.edu.tw/ ) in conjunction with structure-based and ligand-based drug design to identify multi-function Src inhibitors. The three potential TCM candidates identified as having suitable docking conformations and bioactivity profiles were Angeliferulate, (3R)-2'-hydroxy-3',4'-dimethoxyisoflavan-7-O-beta-D-glucoside (HMID), and 3-[2',6-dihydroxy-5'-(2-propenyl)[1,1'-biphenyl]3-yl]-(E)-2-propenoic acid (3PA). Molecular dynamics simulation demonstrated that the TCM candidates have more stable interactions with the cleft and in complex with Src kinase compared to Saracatinib. Angeliferulate and HMID, both originated from Angelica sinensis, not only interact with Lys298 and amino acids from different loops in the cleft, but also with Asp407 located on the activation loop. These interactions are important to reduce the opening of the activation loop due to phosphorylation, hence stabilize the Src kinase cleft structure and inhibit activation. The TCM candidates also exhibited high affinity to other cancer-related target proteins (EGFR, HER2, and HSP90). Our observations suggest that the TCM candidates might have multi-targeting effects in hypertension and cancer.