OBJECTIVETo investigate the expression of Csk-binding protein (CBP) in esophageal carcinoma and its association with the tumorigenesis and progression of esophageal cancer.

METHODSRT-PCR and Western blotting were employed to determine the expressions of CBP at the mRNA and protein levels in 50 pairs of fresh esophageal carcinoma tissue and the adjacent normal tissues.

RESULTSCBP mRNA and protein expressions in normal tissues were 1.43- and 1.28-fold higher than those in the cancer tissues, respectively (P<0.05). The expressions of CBP mRNA and protein were positively correlated (P=0.015). The decreased expressions of CBP were significantly correlated to lymph node metastasis of esophageal cancer (P<0.05).

CONCLUSIONThe expression of CBP gene is decreased in esophageal carcinoma, which might contribute to the tumorigenesis and progression of this malignancy.

Adenocarcinoma ; metabolism ; pathology ; Aged ; Aged, 80 and over ; Carcinoma, Squamous Cell ; metabolism ; pathology ; Down-Regulation ; Esophageal Neoplasms ; metabolism ; pathology ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Lymphatic Metastasis ; Male ; Middle Aged ; RNA, Messenger ; genetics ; metabolism ; src-Family Kinases ; genetics ; metabolism

To investigate the functional role of KAI1/CD82, a metastasis suppressor for human prostate cancer, in the regulation of homotypic cell adhesion, we transfected KAI1 cDNA into DU 145 human prostate cancer cells and established stable transfectant clones with high KAI1/CD82 expression. The KAI1 transfectant cells exhibited significantly increased homotypic cell aggregation in comparison with the control transfectant cells. This aggregation of the KAI1 transfectants was further enhanced upon exposure to anti-CD82 antibody, suggesting that KAI1/CD82 may be involved in the intracellular signaling for the cell adhesion. Among several signal pathway inhibitors tested, PP1, an inhibitor of Src family kinases, significantly suppressed homotypic aggregation of the KAI1 transfectant cells. Ligation of KAI1/CD82 with anti-CD82 antibody increased endogenous Src kinase activity of the KAI1 transfectant cells. When different types of src expression constructs were retransfected into the KAI1-transfected DU 145 cells, kinase-negative mutant src transfectant cells exhibited much lower homotypic aggregation than the mock cells transfected with an empty vector. Moreover, homotypic aggregation of the mutant src transfectant cells was not enhanced by KAI1/CD82 ligation with anti- CD82 antibody. These results suggest that Src mediates the intracellular signaling pathway of KAI1/CD82 for the induction of homotypic adhesion of human prostate cancer cells.
Adenocarcinoma/*metabolism/pathology/*secondary ; Antigens, Surface ; Cell Adhesion/genetics ; Cell Aggregation/genetics ; Gene Expression Regulation ; Genes, Tumor Suppressor ; Genes, src ; Human ; Male ; Membrane Glycoproteins/genetics/*metabolism ; Prostatic Neoplasms/*metabolism/pathology/*secondary ; Signal Transduction/genetics ; Tumor Cells, Cultured ; src-Family Kinases/genetics/metabolism

Annexin A1 (ANXA1) is a kind of endogenous scaffold protein. Previous research showed that ANXA1 could increase markedly with multiple increase of drug resistance in K562/imatinib cell lines in vitro. Here the stable transfection cell strains K562-pEGFP-N1 which was the native control and K562-pEGFP-N1-ANXA1 which can stably express ANXA1 were established using the Lipofectamine 2000 in order to find whether ANXA1 involved in the drug resistance. Cell growth inhibition experiment via MTT and cell proliferation experiment via MTS showed that K562-pEGFP-N1-ANXA1 cell strain was more sensitive to imatinib than the K562-pEGFP-N1 cell strain, and however the ability of proliferation of K562-pEGFP-N1-ANXA1 cell strain did not change compared with the negative control. Western blotting results showed that the expression of proteins in Annexin family did not change; drug resistance proteins, Bcr-Abl/p-Bcr-Abl (Tyr245), Src family kinase for example, did not change; proteins related with cell proliferation and cell cycle, such as ERK1/2MAPK, p-38MAPK, CDK1 and Wee 1, did not change either in the K562-pEGFP-N1-ANXA1 cell strain compared with the negative control. The co-immunoprecipitation result showed that the interaction between ANXA1 and beta-actin in the K562-pEGFP-N1-ANXA1 cell strain increased markedly. The deduction was that ANXA1 may make the K562-pEGFP-N1-ANXA1 cell strain more sensitive to imatinib due to the increased uptake of imatinib via the increase of ANXA1 and the interaction between ANXA1 and beta-actin in the K562-pEGFP-N1-ANXA1 cell strain in vitro.
Actins ; metabolism ; Annexin A1 ; genetics ; metabolism ; Antineoplastic Agents ; pharmacology ; Cell Proliferation ; drug effects ; Drug Resistance, Neoplasm ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; Imatinib Mesylate ; pharmacology ; Immunoprecipitation ; K562 Cells ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Transfection ; src-Family Kinases ; metabolism

Angiotensin II (Ang II) stimulates migration of vascular smooth muscle cell (VSMC) in addition to its contribution to contraction and hypertrophy. It is well established that Rho GTPases regulate cellular contractility and migration by reorganizing the actin cytoskeleton. Ang II activates Rac1 GTPase, but its upstream guanine nucleotide exchange factor (GEF) remains elusive. Here, we show that Ang II-induced VSMC migration occurs in a betaPIX GEF-dependent manner. betaPIX-specific siRNA treatment significantly inhibited Ang II-induced VSMC migration. Ang II activated the catalytic activity of betaPIX towards Rac1 in dose- and time-dependent manners. Activity reached a peak at 10 min and declined close to a basal level by 30 min following stimulation. Pharmacological inhibition with specific kinase inhibitors revealed the participation of protein kinase C, Src family kinase, and phosphatidylinositol 3-kinase (PI3-K) upstream of betaPIX. Both p21-activated kinase and reactive oxygen species played key roles in cytoskeletal reorganization downstream of betaPIX-Rac1. Taken together, our results suggest that betaPIX is involved in Ang II-induced VSMC migration.
1-Phosphatidylinositol 3-Kinase/metabolism ; Angiotensin II/*metabolism ; Animals ; *Cell Movement ; Cells, Cultured ; Guanine Nucleotide Exchange Factors/genetics/*metabolism ; Muscle, Smooth, Vascular/cytology ; Myocytes, Smooth Muscle/*cytology ; NADPH Oxidase/metabolism ; Protein Kinase C/metabolism ; RNA, Small Interfering/genetics ; Rats ; Rats, Sprague-Dawley ; p21-Activated Kinases/metabolism ; rac1 GTP-Binding Protein/metabolism ; src-Family Kinases/metabolism

Viral proteins of gamma-2 herpesviruses, such as LMP2A of Epstein Barr virus (EBV) and Tip of herpesvirus saimiri (HVS) dysregulate lymphocyte signaling by interacting with Src family kinases. K15 open reading frame of Kaposi's sarcoma associated herpesvirus (KSHV), located at the right end of the viral genome, encodes several splicing variants differing in numbers of transmembrane domains. Previously, we demonstrated that the cytoplasmic tail of the K15 protein interfered with B cell receptor signal transduction to cellular tyrosine phosphorylation and calcium mobilization. However, the detailed mechanism underlying this phenomenon was not understood. In the C-terminal cytoplasmic region of K15, putative binding domains for Src-SH2 and -SH3 were identified. In this study, we attempted to characterize these modular elements and cellular binding protein(s) by GST pull down and co-immunoprecipitation assays. These studies revealed that K15 interacted with the major B cell tyrosine kinase Lyn. In vitro kinase and transient co-expression assays showed that the expression of K15 protein resulted in activation of Lyn kinase activity. In addition, GST pull down assay suggested that the SH2 domain of Lyn alone was necessary for interaction with the C-terminal SH2B (YEEV) of K15, but the addition of Lyn SH3 to the SH2 domain increases the binding affinity to K15 protein. The data from luciferase assays indicate that K15 expression in BJAB cells induced NFAT and AP1 activities. The tyrosine residue in the C-terminal end of K15 required for the Lyn interaction appeared to be essential for NFAT/AP1 activation, highlighting the significance of the C-terminal SH2B of K15 as a modular element in interfering with B lymphocyte signaling through interaction with Lyn kinase.
Cell Line ; Herpesvirus 8, Human/genetics/*metabolism ; Humans ; Immunoblotting ; Immunoprecipitation ; Membrane Proteins/genetics/*metabolism ; NFATC Transcription Factors/genetics/*metabolism ; Phosphorylation ; Protein Binding ; Sarcoma, Kaposi/virology ; Transcription Factor AP-1/genetics/*metabolism ; Transfection ; Viral Proteins/genetics/*metabolism ; src-Family Kinases/genetics/*metabolism

To study the effect of sodium aescinate in inducing human breast cancer MCF-7 cells apoptosis and its possible mechanism. MTT assay was used to detect the inhibitory effect of sodium aescinate on the proliferation of MCF-7 cells. The morphological changes were observed under inverted microscope. DAPI nuclear staining was used to detect the changes in cell nucleus. Annexin V-FITC/PI flow cytometry was adopted to test the apoptosis rate. Changes in apoptosis-related proteins (PARP, cleaved caspase-8 and pro-caspase-3), cell survival-associated signal molecules (AKT and ERK) and their common upstream kinase SRC was detected by Western blotting. The result showed that after different concentrations of sodium aescinate were used to treat breast cancer MCF-7 cells, they inhibited the proliferation of MCF-7 cells in a dose-dependent manner, induced cell apoptosis (typical morphological changes in nucleus, significant increase in cell apoptosis rate). The expressions of cleaved PARP and caspase-8 increased, while the expression of pro-caspase-3 decreased, which further verified sodium aescinate's effect in inducing cell apoptosis. Sodium aescinate significantly inhibited the phosphorylation of cell survival-related signal molecules (AKT, ERK) and down-regulate the activation of their common up-stream kinase SRC. The findings indicated that sodium aescinate can block signals transiting to downstream molecules AKT, ERK, inhibit the proliferation of breast cancer cell MCF-7 cell apoptosis and induced cell apoptosis by suppressing the activation of SRC.
Antineoplastic Agents, Phytogenic ; pharmacology ; Apoptosis ; drug effects ; Breast Neoplasms ; drug therapy ; enzymology ; genetics ; physiopathology ; Down-Regulation ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; Extracellular Signal-Regulated MAP Kinases ; genetics ; metabolism ; Female ; Humans ; MCF-7 Cells ; Proto-Oncogene Proteins c-akt ; genetics ; metabolism ; Saponins ; pharmacology ; Signal Transduction ; drug effects ; Triterpenes ; pharmacology ; src-Family Kinases ; genetics ; metabolism

OBJECTIVETo investigate the expression of heat shock protein 90 (HSP90) on the cell surface of highly invasive human prostate cancer cells PC3 and its possible molecular mechanisms of its effect on cell invasion through analyzing FAK/Src signaling pathway.

METHODSThe expression of cell surface HSP90 on PC3 cells was studied by immunofluorescence staining and surface biotinylation assay respectively. A specific HSP90 antibody was used to inhibit the cell surface HSP90. In vitro cell invasion was assessed by modified Boyden chambers. Phosphorylated FAK on tyr 397, 576, 577 and 925, and phosphorylated c-Src on tyr 416 were examined by Western blot assay. The association between FAK and c-Src was analyzed by immunoprecipitation. The effects of FAK knockdown by siRNA or Src kinases inhibitor PP2, with or without anti-HSP90 antibody, on PC3 cell invasion were also evaluated.

RESULTSA pool of HSP90 was detected on the cell surface of PC3 cells. A specific HSP90 antibody significantly retarded tumor cell invasion. Concomitant with this finding, targeting cell surface HSP90 significantly inhibited the phosphorylations of FAK and c-Src, and also the interactions between FAK and c-Src. FAK knockdown or PP2 dramatically suppressed cell invasion, however, anti-HSP90 antibody didn't further inhibit cell invasion.

CONCLUSIONSCell surface HSP90 promotes human prostate cancer cell invasion through a FAK/c-Src signaling, with may be a novel therapeutic target against metastatic tumors.

Antibodies ; pharmacology ; Cell Line, Tumor ; Cell Membrane ; metabolism ; Focal Adhesion Protein-Tyrosine Kinases ; genetics ; metabolism ; Gene Knockdown Techniques ; HSP90 Heat-Shock Proteins ; immunology ; metabolism ; Humans ; Male ; Neoplasm Invasiveness ; Phosphorylation ; Prostatic Neoplasms ; metabolism ; pathology ; Pyrimidines ; pharmacology ; RNA, Small Interfering ; genetics ; Signal Transduction ; Transfection ; src-Family Kinases ; antagonists & inhibitors ; metabolism

Studies on chronic myeloid leukemia (CML) have served as a paradigm for cancer research and therapy. These studies involve the identification of the first cancer-associated chromosomal abnormality and the subsequent development of tyrosine kinase inhibitors (TKIs) that inhibit BCR-ABL kinase activity in CML. It becomes clear that leukemia stem cells (LSCs) in CML which are resistant to TKIs, and eradication of LSCs appears to be extremely difficult. Therefore, one of the major issues in current CML biology is to understand the biology of LSCs and to investigate why LSCs are insensitive to TKI monotherapy for developing curative therapeutic strategies. Studies from our group and others have revealed that CML LSCs form a hierarchy similar to that seen in normal hematopoiesis, in which a rare stem cell population with limitless self-renewal potential gives rise to progenies that lack such potential. LSCs also possess biological features that are different from those of normal hematopoietic stem cells (HSCs) and are critical for their malignant characteristics. In this review, we summarize the latest progress in CML field, and attempt to understand the molecular mechanisms of survival regulation of LSCs.
Animals ; DNA-Binding Proteins ; genetics ; metabolism ; Fusion Proteins, bcr-abl ; antagonists & inhibitors ; metabolism ; Humans ; Hypoxia-Inducible Factor 1 ; metabolism ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; metabolism ; pathology ; Lipid Metabolism ; Neoplastic Stem Cells ; drug effects ; metabolism ; Protein Kinase Inhibitors ; pharmacology ; therapeutic use ; Proto-Oncogene Proteins c-bcl-6 ; src-Family Kinases ; metabolism

Helicobacter pylori (H. pylori) is an important risk factor for chronic gastritis, peptic ulcer, and gastric cancer. Proteinase-activated receptor 2 (PAR2), subgroup of G-protein coupled receptor family, is highly expressed in gastric cancer, and chronic expression of cyclooxygenase-2 (COX-2) plays an important role in H. pylori-associated gastric carcinogenesis and inflammation. We previously demonstrated that H. pylori induced the expression of PAR2 and COX-2 in gastric epithelial cells. Present study aims to investigate whether COX-2 expression induced by H. pylori in Korean isolates is mediated by PAR2 via activation of Gi protein and Src kinase in gastric epithelial AGS cells. Results showed that H. pylori-induced COX-2 expression was inhibited in the cells transfected with antisense oligonucleotide for PAR2 or treated with Gi protein blocker pertussis toxin, Src kinase inhibitor herbimycin A and soybean trypsin inbitor, indicating that COX-2 expression is mediated by PAR2 through activation of Gi protein and Src kinase in gastric epithelial cells infected with H. pylori in Korean isolates. Thus, targeting the activation of PAR2 may be beneficial for prevention or treatment of gastric inflammation and carcinogenesis associated with H. pylori infection.
Benzoquinones/*pharmacology ; Cell Line, Tumor ; Cyclooxygenase 2/genetics/*metabolism ; Epithelial Cells/enzymology/metabolism/microbiology ; GTP-Binding Protein alpha Subunits, Gi-Go/metabolism ; Gastric Mucosa/enzymology/metabolism/*microbiology ; *Helicobacter pylori ; Humans ; Lactams, Macrocyclic/*pharmacology ; Oligonucleotides, Antisense ; Pertussis Toxin/*pharmacology ; RNA, Messenger/metabolism ; Receptor, PAR-2/*physiology ; src-Family Kinases/metabolism

Earlier report showed that expression of a splice variant of CD99 transmembrane protein increases invasive ability of human breast cancer cells. Cell motility was also significantly enhanced by the CD99 splice variant expression. In an effort to identify the cellular components that mediate a signal transduction pathway triggered by the CD99 splice variant, known signal path inhibitors were examined for their effects on the motility of the CD99 splice variant-transfected MDA-MB-231 breast cancer cells. Phenylarsine oxide, an inhibitor of phosphatase specific for focal adhesion kinase, and PP1, an inhibitor of src kinase family, significantly suppressed motility of the cells. Among different types of src transfectant clones generated, kinase-negative mutant src transfectant cells were 80% less motile than the mock cells transfected with an empty-vector, while v-src and c-src transfectants exhibited cell motility levels at or slightly above the mock transfectant. These results suggest that src and focal adhesion kinase mediate the intracellular signaling pathway of a CD99 splice variant for the induction of motility of human breast cancer cells.
Antigens, CD/*genetics ; Arsenicals/pharmacology ; Breast Neoplasms/*enzymology/genetics/*pathology ; Cell Adhesion Molecules/*genetics ; Cell Movement/drug effects ; Gene Expression ; Protein-Tyrosine Kinase/antagonists & inhibitors/*metabolism ; Pyrazoles/pharmacology ; Pyrimidines/pharmacology ; Signal Transduction/drug effects ; Transfection ; Tumor Cells, Cultured ; src-Family Kinases/antagonists & inhibitors/*metabolism