PURPOSE: The activation of phospholipase C (PLC) is one of the early events in various growth processes, including malignant transformation. Among PLC-isozymes, PLC-gamma is activated through direct interaction with growth factor receptor tyrosine kinase. In this study, we evaluated the patterns of PLC-gamma expression in benign and malignant tumors of the breast and compared the patterns with their normal counterpart. METHODS: Using immunoblot assay, we evaluated the patterns of expression in PLC-gamma in 20 breast cancer tissues, 13 fibroadenoma tissues, and normal tissues. The level of expression was analyzed by densitometry. RESULTS: All of 20 breast cancer tissues and 13 fibroadenoma tissues showed overexpression of PLC-gamma when compared with their normal counterparts. The level of the PLC-gamma expression was 3.9-fold and 17.3-fold higher in fibroadenomas and breastcancers, respectively, than in normal tissues. CONCLUSION: The result suggested that the level of PLC-gamma expression increases as the normal tissue undergoes progression to fibroadenoma, and finally to carcinoma. The pattern of expression of PLC-gamma in breast tissue implies that the PLC-gamma-mediated signal transduction may play a significant role in the progression of breast cancer from normal tissue.
Breast Neoplasms ; Breast* ; Densitometry ; Fibroadenoma ; Phospholipase C gamma ; Phospholipases* ; Protein-Tyrosine Kinases ; Signal Transduction ; Type C Phospholipases

OBJECTIVETo investigate the changes in the expression of phospholipase C-gamma1tyr783 (PLC-γ1tyr783) in the condylar cartilage of a young rat during functional mandibular protraction. This work also explores the function of PLC-γ1tyr783 in the rat mandibular condylar cartilage bone remodeling, which could provide experimental evidence for clinical bone ortho- pedic work.

METHODSA total of 60 four-week-old male Sprague-Dawley (SD) rats were used in this study. The rats were divided equally and randomly into experimental group and control group. The functional appliances that were fitted to the upper incisors of the animals in the experimental group were worn 24 h a day after the rats were fed for 7 d with homemade pellet feed. The animals in the experimental group, along with their matched controls, were sacrificed after 1, 3, 7, 14, 21, and 28 d. The bilateral condylar was fixed, decalcified, dehyded, and then conventional paraffin embedded. Immunohisto- chemistry of PLC-γ1tyr783 was applied to observe its express distribution and variation.

RESULTSThe expression of PLC-&gamma;1tyr783 decreased gradually in the control group, which showed age-related changes (P > 0.05). On the 14th day, PLC-&gamma;1tyr783 expres- sion in the experimental group was significantly higher than that in the control group. PLC-&gamma;1tyr783 expression began to appear statistically and significantly different between the two groups (P < 0.01).

CONCLUSIONPLC-&gamma;1tyr783 is involved in the bone remodeling process of the rat condylar cartilage after functional mandibular-protraction.

Animals ; Bone Remodeling ; Cartilage ; Male ; Mandibular Condyle ; Phospholipase C gamma ; Phosphoric Diester Hydrolases ; Rats ; Rats, Sprague-Dawley

Phosphatidylinositol phosphates (PtdInsPs) are ubiquitous membrane phospholipids that play diverse roles in cell growth and differentiation. To clarify the regulation mechanism acting on neurofilament light chain (NF-L) self assembly, we examined the effects of various PtdInsPs on this process. We found that PtdInsPs, including PI(4,5)P2, directly bind to the positively charged Arg54 of murine NF-L, and this binding promotes NF-L self assembly in vitro. Mutant NF-L (R53A/R54A) proteins lacking binding affinity to PtdInsPs did not have the same effect, but the mutant NF-L proteins showed greater self assembly than the wild-type in the absence of any PtdInsP. These results collectively suggest that Arg54 plays a pivotal role in NF-L self assembly by binding with PtdInsPs.
Animals ; Fluorescent Antibody Technique ; Mice ; Mutation/genetics ; Neurofilament Proteins/genetics/*metabolism ; Phosphatidylinositol Phosphates/*metabolism ; Phospholipase C gamma/metabolism ; *Protein Multimerization

Cytologic diagnosis of reactive or malignant effusion is sometimes difficult. Espe- cially, differentiation of benign reactive mesothelial cells from malignant cells in body effusion is more difficult. Recently, immunohistochemistry has been used to diagnose difficult cases. Phospholipase C(PLC)-gamma 1 is one of the isoenzyme of the PLC which plays central role in signal transduction involving cellular growth, differentiation and transformation by phosphorylating many protein component. Increased expression of PLC-gamma 1 in human breast carcinoma, colorectal carcinoma and stomach cancers are reported. To evaluate the efficacy of positive PLC-gamma 1 immunostaining in the diagnosis of malignancy in effusions, paraffin-embedded cell blocks of pleural fluid and ascites from 10 patients(5 metastatic adenocarcinomas, and 5 reactive mesothelial cells) were immunostained with a monoclonal antibody to PLC-gamma 1. PLC-gamma 1 immuostained all the adenocarcinomas in cell block(5/5) with intense membrane pattern, however, none of the reactive mesothelial proliferations stained with the diagnostic membrane pattern. Thus, our study strongly supports the conclusion that PLC-gamma 1 immunopositivity is likely to become a useful adjunct for the diagnosis of malignancy in effusions.
Adenocarcinoma* ; Ascites ; Breast Neoplasms ; Colorectal Neoplasms ; Diagnosis ; Humans ; Immunohistochemistry ; Membranes ; Phospholipase C gamma ; Phospholipases ; Signal Transduction ; Stomach Neoplasms

Regulation of B cell receptor (BCR)-induced Ca2+ signaling by CD40 co-stimulation was compared in long-term BCR-stimulated immature (WEHI-231) and mature (Bal-17) B cells. In response to long-term pre-stimulation of immature WEHI-231 cells to alpha-IgM antibody (0.5~48 hr), the initial transient decrease in BCR-induced [Ca2+]i was followed by spontaneous recovery to control level within 24 hr. The recovery of Ca2+ signaling in WEHI-231 cells was not due to restoration of internalized receptor but instead to an increase in the levels of PLCgamma2 and IP3R-3. CD40 co-stimulation of WEHI-231 cells prevented BCR-induced cell cycle arrest and apoptosis, and it strongly inhibited the recovery of BCR-induced Ca2+ signaling. CD40 co-stimulation also enhanced BCR internalization and reduced expression of PLCgamma2 and IP3R-3. Pre-treatment of WEHI-231 cells with the antioxidant N-acetyl-L-cysteine (NAC) strongly inhibited CD40-mediated prevention of the recovery of Ca2+ signaling. In contrast to immature WEHI-231 cells, identical long-term alpha-IgM pre-stimulation of mature Bal-17 cells abolished the increase in BCR-induced [Ca2+]i, regardless of CD40 co-stimulation. These results suggest that CD40-mediated signaling prevents antigen-induced cell cycle arrest and apoptosis of immature B cells through inhibition of sustained BCR-induced Ca2+ signaling.
Acetylcysteine ; Apoptosis ; B-Lymphocytes ; Cell Cycle Checkpoints ; Phospholipase C gamma ; Precursor Cells, B-Lymphoid ; Reactive Oxygen Species

OBJECTIVETo explore the role of phospholipase C-gamma1 (PLC-gamma1) signaling pathway in H(2)O(2)-induced apoptosis of PC12 cells.

METHODSPC12 cells were exposed to 50 micromol/L H(2)O(2) after pretreatment with 10 micromol/L U73122, a specific PLC-gamma1 inhibitor. Hoechst/PI double staining was performed to observe the morphological changes of the cells under light microscope. MTT assay was used to evaluate the cell viability, and the percentage of apoptotic cells was analyzed by flow cytometry. DNA fragmentation assay was carried out to characterize the cell apoptosis.

RESULTSAfter inhibition of the PLC-gamma1 signaling pathway with 10 micromol/L U73122, PC12 cells showed obvious apoptotic morphology, the viable cells decreased significantly, and the percentage of apoptotic cells rose to 35.7%. PC12 cells treated with U73122 presented with a distinct DNA ladder on electrophoresis resulting from DNA cleavage in the apoptotic cells.

CONCLUSIONPLC-gamma1 signaling pathway plays an important protective role in H(2)O(2)-induced PC12 cell apoptosis.

Animals ; Apoptosis ; drug effects ; Estrenes ; pharmacology ; Hydrogen Peroxide ; pharmacology ; PC12 Cells ; Phospholipase C gamma ; antagonists & inhibitors ; metabolism ; Pyrrolidinones ; pharmacology ; Rats ; Signal Transduction

To investigate the expression of phospholipase C-gamma1 (PLC-gamma1) in mouse embryonic tissues, serial tissue sections were prepared routinely for immunocytochemistry for PLC-gamma1. The results showed that PLC-gamma1 was expressed in the cartilage, skeletal muscles, myocardium, the collecting tubule of the kidney, connective tissues and the brain, suggesting the important role PLC-gamma1 and the related signal pathway may play in the development of mouse embryonic tissues.
Animals ; Brain ; embryology ; enzymology ; Cartilage ; embryology ; enzymology ; Embryo, Mammalian ; enzymology ; Female ; Fetal Heart ; enzymology ; Immunohistochemistry ; Kidney ; embryology ; enzymology ; Mice ; Muscle, Skeletal ; embryology ; enzymology ; Phospholipase C gamma ; biosynthesis ; Pregnancy

OBJECTIVETo study the effects of lipid rafts on cell signal transmembrane transduction mediated by c-Met.

METHODSAfter HepG2Cells were treated with MbCD to disrupt the lipid rafts and were treated with artificial recombination hepatocyte growth factor to activate c-Met, the activities of PLCr1/PKC, PI3K/Akt and MAPK signaling pathways in HepG2 cells were analyzed using Western blot.

RESULTS(1) After disruption of lipid rafts with MbCD, phosphorylation of PLCr1 decreased by 35% (P = 0.022); the content of PLCr in the cytoplasm increased by 1.75 fold (P = 0.017); PLCr1 conjugated with membrane decreased by 30% (P = 0.037). (2) The content of PKB in the cytosol decreased by 38% (P = 0.028), and the phosphorylation level of PKB conjugated with membrane decreased by 14% (P = 0.041). At the same time, PDK translocation from cytosol to the plasma membrane and its activation were inhibited by treatment with MbCD. (3) Treatment with MbCD had no significant effect on ErK/MAPK, p38/MAPK and JNK/MAPK signaling pathways.

CONCLUSIONDisruption of lipid rafts with MbCD inhibits the activation of PLCr1/PKC and PI3K/PKB signaling pathways by HGF/cMet, but has no effect on MAPK signaling pathway.

Hep G2 Cells ; Humans ; Membrane Microdomains ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Phospholipase C gamma ; metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; metabolism ; Proto-Oncogene Proteins c-met ; metabolism ; Signal Transduction

We report two cases of gingival plasma cell granuloma in a 34-yr-old and 40-yr-old two male renal transplant recipients with cyclosporine A (CsA)-induced gingival overgrowth (GO). Histologically, these lesions were composed of mature plasma cells, showing polyclonality for both lambda and kappa light chains and fibrovascular connective tissue stroma. In addition to the fact that CsA-induced plasma cell granuloma is rare, the salient features of our cases were the secretion of interleukin-6 and overexpression of phospholipase C-gamma1 of the tumor cells, which may explain the mechanisms of CsA- induced GO.
Cyclosporine/adverse effects ; Female ; Gingival Diseases/*chemically induced/enzymology/immunology/pathology ; Granuloma, Plasma Cell/*chemically induced/enzymology/immunology/pathology ; Humans ; Immunohistochemistry ; Immunosuppressive Agents/adverse effects ; Interleukin-6/metabolism ; Kidney Transplantation ; Male ; Middle Aged ; Phospholipase C gamma ; Type C Phospholipases/metabolism

OBJECTIVESTo explore the mechanism of CBRH-7919 cell proliferation inhibition by transfecting phosphatidylethanolamine N-methyltransferase 2 gene (PEMT2).

METHODSThe effects of PEMT2 transfection on phosphorylation and translocation from cytosol to plasma membrane of PLC gamma 1 in cells were studied using SDS-PAGE and Western blot techniques. The phosphorylation and activity of c-Met were determined.

RESULTSAfter transfection of pemt2, the PLC gamma 1 and phosphorylated PLC gamma 1 conjugated with plasma membrane were decreased by 45% and 27% of that of control cells respectively, and the phosphorylated c-Met was decreased to 32% of that of control cells.

CONCLUSIONTransfection of phosphatidylethanolamine N-methyltransferase 2 gene can inhibit the phosphorylation and translocation from cytosol to plasma membrane of PLC gamma 1 in cells. At the same time, the autophosphorylation of c-Met was decreased, which suggests that transfection of phosphatidylethanolamine N-methyltransferase 2 gene can downregulate the c-Met/PLC gamma 1 signaling pathway in CBRH-7919 cells.

Animals ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Liver Neoplasms, Experimental ; Phosphatidylethanolamine N-Methyltransferase ; genetics ; metabolism ; Phospholipase C gamma ; genetics ; metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-met ; metabolism ; Rats ; Transfection