Determination of matrix metalloproteinase activity using biotinylated gelatin

Matrix metalloproteinases (MMPs) and, specifically, MMP-2 (gelatinase A) and MMP-9 (gelatinase B) are strongly associated with malignant progression and matrix remodeling. These enzymes are a subject of intensive studies involving screening of comprehensive chemical libraries of synthetic inhibitors. There is no simple method available for measurement of activity of gelatinases and related MMPs. Here, we report a simple, inexpensive, and highly sensitive assay for MMP activity. The assay performed in a 96-well microtiter plate format employs biotin-labeled gelatin (denatured collagen type I) as a substrate. Following the substrate cleavage, only the proteolytic fragments bearing biotin moieties are captured by streptavidin coated on the plastic surface and the captured fragments with at least two biotin molecules should be revealed by streptavidin conjugated with horseradish peroxidase. The frequency of lysine residues is low in collagen type I relative to the MMP cleavage sequences (PXGX). Accordingly, the majority of the cleavage products must be devoid of biotin or possess only one biotin group. Both of these types of fragments cannot be recognized by the horseradish peroxidase-streptavidin conjugate. Therefore, higher gelatinolytic activity is associated with lower signal in the assay. This 2-h assay allows identification of gelatinolytic activity of MMP-2 in concentrations as low as 0.16 ng/ml. The sensitivity of this ELISA-like assay is comparable to that of gelatin zymography, a method widely used to detect gelatinases. However, in contrast to zymography, the assay directly measures the enzymatic activity of MMP samples. The gelatinolytic activity assay permits efficient analyses and screening of the MMP inhibitor panels and allows quantitation of gelatinolytic activity of various MMPs in solution as well as on cell surfaces.

[Expression of bcl-2 and p16 in transitional cell carcinoma of urinary bladder]

OBJECTIVE

To study the relationship between the expression of proto-oncogene bcl-2 and MTS1/p16 in transitional cell carcinoma of bladder and prognosis.

METHODS

Immunohistochemical SABC method was used to detect the expression of proto-oncogene bcl-2 and MTS1/p16 in 51 paraffin-embedded primary transitional cell carcinoma of bladder specimens and 5 normal bladder mucosa specimens.

RESULTS

The positive expression of bcl-2 was seen in 80.2% (42/51) tumors. There was statistically significant correlation between prognosis and the positive expression of bcl-2. The positive expression rate was higher in tumors with poorer prognosis than in those with better prognosis (P < 0.05). The expression of p16 protein was positive in 50.9% (26 of 51) in tumors and negative in all 5 normal bladder mucosae. The positive expression rate of p16 descended with increasing grade, stage and poorer prognosis. Clinicopathological characteristics and prognosis were related to the expression of p16 (P < 0.05). The positive expression of bcl-2 versus negative expression of p16 were seen in 20 of 51 of tumors, with distributing grade I 3/11, grade II 9/26, grade III 8/14, Tis - T(1) 6/28, T(2) 10/17, T(3) 4/6, A group 5/20, B group 4/16, and C group 11/15, respectively. Both bcl-2 and p16 were positively expressed in 22 of 51 of tumors. Their positive expressions were higher in tumors with lower grade, stage and better prognosis than in those with worse clinicopathological characteristics and poorer prognosis (P < 0.05).

CONCLUSIONS

Over-expression of bcl-2 appears to be common in bladder cancer; over-expression of proto-oncogene bcl-2 and inactivation of the MTS1/p16 gene are likely to be contributing factors for primary bladder cancer; and they can be the prognostic indicators for transitional cell carcinoma of urinary bladder.

Evidence of apoptotic smooth muscle cells in proliferative intima of injured arteries

OBJECTIVE

To investigate the occurrence and extent of apoptosis in the course of restenosis.

METHODS

The experimental models of vessel narrowness and intima thickness were established in minipigs' iliac arteries by balloon injury and specimens were retrieved on the 1st, 3rd, 6th, 12th and 30th days for dynamic observation. Apoptotic smooth muscle cells (SMCs) were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL).

RESULTS

Apoptotic SMCs occurred only in the thickened intima 12 days after injury accompanied with the proliferative SMCs, the percentage of apoptosis was 1.94% +/- 0.42% on the 12th day and 1.36% +/- 0.31% on the 30th day respectively. The low frequency of apoptosis compared with the proliferative SMCs was a feature in the restenotic pathology.

CONCLUSIONS

Apoptosis participates in the pathogenetic process of intimal thickening and its level was low compared with proliferation. The findings suggest that attempts to modulate apoptosis after vessel injury constitute a theoretical approach to the prevention of restenosis.

Potentiation of cell migration by adhesion-dependent cooperative signals from the GTPase Rac and Raf kinase

The small GTPase Rac is thought to regulate cell movement by influencing actin cytoskeletal organization and membrane ruffling. However, cell migration also depends on the activation of mitogen-activated protein kinase (MAPK), which can regulate myosin motor function, an event critical for cell contraction. Evidence is provided that, during active cell adhesion to the extracellular matrix, Rac potentiates the MAPK pathway and influences cell migration by selectively synergizing with Raf kinase but not with Ras or MAPK kinase. In fact, the synergy between Rac and Raf kinase increases the chemotactic sensitivity of cells to epidermal growth factor by 1000-fold. Therefore, the role of Rac in cell migration not only depends on its ability to regulate actin cytoskeletal organization but also on its capacity to potentiate chemokine activation of MAPK in a manner that depends on active cell adhesion to the extracellular matrix.

Selective requirement for Src kinases during VEGF-induced angiogenesis and vascular permeability

Src kinase activity was found to protect endothelial cells from apoptosis during vascular endothelial growth factor (VEGF)-, but not basic fibroblast growth factor (bFGF)-, mediated angiogenesis in chick embryos and mice. In fact, retroviral targeting of kinase-deleted Src to tumor-associated blood vessels suppressed angiogenesis and the growth of a VEGF-producing tumor. Although mice lacking individual Src family kinases (SFKs) showed normal angiogenesis, mice deficient in pp60c-src or pp62c-yes showed no VEGF-induced vascular permeability (VP), yet fyn-/- mice displayed normal VP. In contrast, inflammation-mediated VP appeared normal in Src-deficient mice. Therefore, VEGF-, but not bFGF-, mediated angiogenesis requires SFK activity in general, whereas the VP activity of VEGF specifically depends on the SFKs, Src, or Yes.

[Localization and quantitative analysis of insulin-like growth factor-I in placenta of extreme fetus]

OBJECTIVE

To investigate the immunohistochemical localization of insulin-like growth factor-I (IGF-I) in human placenta and to evaluate the role of IGF-I in fetal growth and placental growth.

METHODS

In 72 tested samples, The cellular distribution of IGF-I in human placenta was determined by using immunohistochemistry. The relative area and mean absorbance were determined by using image analysis technique. Student's t-test was used to compare mean values between groups.

RESULTS

IGF-I immunostaining was found in syncytiotrophoblast, cytotrophoblast and Hoffbauer's cells of chorionic villi and chorion of fetal membranes. The strongest immunoreactivity was observed in the syncytiotrophoblast and cytotrophoblast. The relative area and absorbance in placenta of SGA group were significantly lower than those of AGA group respectively (t = 4.65, P < 0.001; t = 2.15, P < 0.05). But the relative arca and absorbance of LGA were significantly higher than those of AGA (t = 8.72, P < 0.001; t = 7.82, P < 0.001).

CONCLUSION

These results suggested that IGF-I in human placenta was principally synthsized and secreted by syncytiotrophoblast, cytotrophoblast, hoffbauer's cells of chorionic villi and chorion of fetal membranes. IGF-I is an improtant regulator of fetal and placental growth and development. It has the key role for macrosomia and IUGR forming.

Activation of Rac and Cdc42 by integrins mediates cell spreading

Adhesion to ECM is required for many cell functions including cytoskeletal organization, migration, and proliferation. We observed that when cells first adhere to extracellular matrix, they spread rapidly by extending filopodia-like projections and lamellipodia. These structures are similar to the Rac- and Cdc42-dependent structures observed in growth factor-stimulated cells. We therefore investigated the involvement of Rac and Cdc42 in adhesion and spreading on the ECM protein fibronectin. We found that integrin-dependent adhesion led to the rapid activation of p21-activated kinase, a downstream effector of Cdc42 and Rac, suggesting that integrins activate at least one of these GTPases. Dominant negative mutants of Rac and Cdc42 inhibit cell spreading in such a way as to suggest that integrins activate Cdc42, which leads to the subsequent activation of Rac; both GTPases then contribute to cell spreading. These results demonstrate that initial integrin-dependent activation of Rac and Cdc42 mediates cell spreading.

CAS/Crk coupling serves as a "molecular switch" for induction of cell migration

Carcinoma cells selected for their ability to migrate in vitro showed enhanced invasive properties in vivo. Associated with this induction of migration was the anchorage-dependent phosphorylation of p130CAS (Crk-associated substrate), leading to its coupling to the adaptor protein c-CrkII (Crk). In fact, expression of CAS or its adaptor protein partner Crk was sufficient to promote cell migration, and this depended on CAS tyrosine phosphorylation facilitating an SH2-mediated complex with Crk. Cytokine-stimulated cell migration was blocked by CAS lacking the Crk binding site or Crk containing a mutant SH2 domain. This migration response was characterized by CAS/Crk localization to membrane ruffles and blocked by the dominant-negative GTPase, Rac, but not Ras. Thus, CAS/Crk assembly serves as a "molecular switch" for the induction of cell migration and appears to contribute to the invasive property of tumors.

Overexpression of p53, EGFR, c-erbB2 and c-erbB3 in endometrioid carcinoma of the ovary

OBJECTIVES

To determine overexpression of p53, EGFR, c-erbB-2 and c-erbB-3 in endometrioid carcinoma of the ovary and to evaluate the prognostic significance of these results, especially, coexisting overexpression of p53 and one of the member of type I growth factor receptor family.

METHODS

Overexpressions of the p53, EGFR, c-erbB-2 and c-erbB-3 protein were studied by immunohistochemistry in paraffin-embedded tumor tissue from 28 patients with endometrioid carcinoma of the ovary.

RESULTS

11 (39.3%), 13 (46.4%), and 14 (50.0%) were stained positively with p53, c-erbB-2 and c-erbB-3 monoclonal antibodies. 13 (46.4%) was stained positively with EGFR polyclonal antibody. There were no relationship between p53, EGFR, C-erbB-2, c-erbB-3 and histologic grade, lymph node metastasis. The percentage of tumors with over expression of p53, EGFR, C-erbB-2 and c-erbB-3 was higher in those with stage II-III tumors compared with those with stage I, in patients with residual tumor after initial surgery compared with those without. A high survival rate was observed in patients without p53, EGFR, c-erbB-2 and c-erbB-3 overexpression respectively than those with. A highest survival rate was observed in patients with both p53 and one of EGFR, c-erbB-2 and c-erbB-3 negative compared with those both positive or either of both positive.

CONCLUSION

Overexpression of p53, EGFR, c-erbB-2 and C-erbB-3 resulted in a poorer prognosis respectively. Overexpression of both p53 and one of the EGFR, c-erbB-2 and c-erbB-3 is a worse prognostic indicator in patients with endometrioid carcinoma of the ovary.

[The effect of splenectomy on alveolar macrophages morphology and function]

OBJECTIVE

To study the morphological and functional changes of pulmonary alveolar macrophages of rats after splenectomy, and the applied effects of splenic tissue autotransplantation in practice.

METHODS

87 Wistar rats were randomly divided into shamoperation group, splenectomy group and splenic tissue autotransplantation group. Six months after splenectomy, alveolar macrophges were subjected to brochoalveolar lavage described by Shennib. The dynamic survival and adherent rate of alveolar macrophages in culture, lysosomal enzyme content, hydrogen peroxide production and expression level of interleukin 1 (IL-1) activity of alveolar macrophages were quantitatively measured. The alveolar macrophages ultrastructure was observed by utilizing transmission electron microscope.

RESULTS

The splenectomized rat's alveolar macrophages were different from alveolar macrophages of sham-operated rats. Their surface filopodia was reduced and shortened, lysosome fewer and its acid phosphatase quantity decreased, adherence postponed, hydrogen peroxide production and expression of IL-1 activity impaired. Splenic tissue autotransplantation fairly restored the splenic effects on maturation and function of alveolar macrophages.

CONCLUSION

Splenic tissue autotransplantation is a simple useful operation for preserving splenic function after splenectomy.

[Expression of epidermal growth factor receptor (EGFR) in endometrioid carcinoma of the ovary]

OBJECTIVE

To determine the expression of EGFR expression in endometrioid carcinoma of the ovary and its relationship to clinicopathologic features and prognosis.

METHODS

Expression of EGFR oncoprotein was studied by immunohistochemistry in paraffin-embedded tumor tissues from 28 patients with endometrioid carcinoma of the ovary.

RESULTS

Tissues from 13 patients (46.4%) were stained positively with EGFR polyclonal antibody (1005). The staining was membranous and/or cytoplasmic. There was no relationship between EGFR expression and age at diagnosis, preoperative CA125 titer, clinical stage, histologic grade, and lymph node metastases. A higher expression rate was observed in patients with residual tumors (56.3% versus 33.3%). The mortality rate was higher in patients with EGFR expression than in those without EGFR expression (46.2% versus 14.3%), but the difference was not statistically significant.

CONCLUSION

EGFR expression was not related to the clinicopathologic features in endometrioid carcinoma of the ovary, but was related to the poor prognosis of this disease.

Isolation and cloning of a protein-serine/threonine phosphatase from an archaeon

A divalent metal ion-stimulated protein-serine/threonine phosphatase, PP1-arch, was purified approximately 1,000-fold from the extreme acidothermophilic archaeon Sulfolobus solfataricus (ATCC 35091). Purified preparations contained 40 to 70% of total protein as PP1-arch, as determined by assay-ing sodium dodecyl sulfate-polyacrylamide gels for protein phosphatase activity. The first 25 amino acids of the protein's sequence were identified, as well as an internal sequence spanning some 20 amino acids. Using this information, we cloned the gene for PP1-arch via the application of PCR and conventional cloning techniques. The gene for PP1-arch predicted a protein of 293 amino acids that bore striking resemblance to the members of the major family of protein-serine/threonine phosphatases from members of the domain Eucarya, the PP1/2A/2B superfamily. The core of the protein, spanning residues 4 to 275, possessed 29 to 31% identity with these eucaryal protein phosphatases. Of the 42 residues found to be absolutely conserved among the known eucaryal members of the PP1/2A/2B superfamily, 33 were present in PP1-arch. If highly conservative substitutions are included, this total reached 37. The great degree of sequence conservation between molecules from two distinct phylogenetic domains implies that the members of this enzyme superfamily had evolved as specialized, dedicated protein phosphatases prior to the divergence of members of the Archaea and Eucarya from one another.

[Chemotherapy through selective pelvic artery catheterization complicated by mural thrombosis]

Through catheter on uterine artery digital subtractive angiography (DSA) intraarterial infusion of chemotherapeutic agents for the treatment of malignant trophoblastic diseases can raise local drug concentration, improve therapeutic results and reduce general side-effects. But mural thrombosis, a possible complication of intra arterial catheterization, should not be overlooked. This study reports 2 cases of mural thrombosis complication in selective pelvic artery catheterization for chemotherapy. The incidence, relevant factors to its occurrence such as technique of catheterization and the duration of catheter retention, as well as measures of prevention and treatment of mural thrombosis are discussed together with review of literature. With regards to prevention of mural thrombosis, stress is being laid on the importance of the technique of catheterization. Preliminary comments on the problem of heparin administration as a preventive measure of mural thrombosis are made.

Identification of a serine/threonine-specific protein phosphatase from the archaebacterium Sulfolobus solfataricus

We have observed that soluble extracts from the extreme acidothermophilic archaebacterium Sulfolobus solfataricus contained protein phosphatase activity that was greatly stimulated by the divalent metal ions Mn2+, Mg2+, Ni2+, or Co2+. This activity apparently arose from a single enzyme since (a) stimulation by these divalent metal ions was not additive and (b) protein phosphatase activity eluted as a single peak from both a DE52 ion-exchange column and a Sephadex G-100 gel filtration column. Its apparent molecular mass was approximately 28,000 daltons. The enzyme dephosphorylated a variety of phosphoserine-containing substrates including casein, histone H2a, phosphorylase kinase, or glycogen phosphorylase. The enzyme would not dephosphorylate either histone H1 or a number of phosphotyrosine-containing compounds. It removed only half the phosphate bound to histone H2b, which is phosphorylated at two sites by the cAMP-dependent protein kinase. Protein phosphatase activity was inhibited by EDTA, Cu2+, Zn2+, NaF, inorganic phosphate, or pyrophosphate; but was unaffected by other potential activators and inhibitors such as microcystin, okadaic acid, vanadate, polyamines, or sulfhydryl modifying reagents. This enzyme represents the first protein phosphatase to be identified in any member of the third and oldest phylogenetic kingdom in nature, the archaebacteria.

The MgATP-binding site on chicken gizzard myosin light chain kinase remains open and functionally competent during the calmodulin-dependent activation-inactivation cycle of the enzyme

An ATP-like affinity labeling reagent, 5'-[p-(fluorosulfonyl)benzoyl]adenosine (FSBA), was used to probe the MgATP-binding site of smooth muscle myosin light chain kinase from chicken gizzard (smMLCK) and its calmodulin (CaM) complex. Native smMLCK has an absolute requirement for the binding of the calcium complex of CaM for expression of its catalytic activity. FSBA reacted with smMLCK-CaM and with the CaM-free, inactive enzyme as well. Both reactions were dependent on time and FSBA concentration. Reaction was accompanied by the incorporation of covalently bound [14C]FSBA into smMLCK protein at a molar ratio of approximately 1:1 in each case. p-(Fluorosulfonyl)benzoic acid, an analogue of FSBA lacking the adenosine targeting group, did not react at a significant rate with either form of smMLCK. Reaction of CaM-free and CaM-bound smMLCK with FSBA displayed saturation kinetics. The first-order rate constants for the conversion of the reversible, noncovalent enzyme-FSBA complex to form the irreversibly inhibited, covalently modified enzyme were similar for both smMLCK and smMLCK-CaM, 0.15 and 0.07 min-1, respectively. The concentrations of FSBA yielding the half-maximal rate of inactivation, KI, were essentially identical--0.65 and 0.64 mM, respectively--for smMLCK and smMLCK-CaM. MgATP, but not MgGTP or a substrate peptide, potently inhibited reaction with FSBA. Inhibition by MgATP was competitive. The measured inhibitory constant for MgATP was essentially the same--33 versus 34 microM--for both smMLCK and smMLCK-CaM. It therefore is concluded that the MgATP-binding site on smMLCK remains accessible and recognizable as such when the enzyme becomes inactivated upon dissociation of CaM.

[A study of duck hepatitis B virus infection in Chinese ducklings]

Intraperitoneal inoculation of duck hepatitis B virus in three different dosages (9 x 10(7), 1.8 x 10(8), 9 x 10(8) DHBV particles) into 3 to 21 day-old Chinese ducklings provided from a DHBV free flock produced a persistent infection up to 93.3% in 60 animals. The serum and liver specimens of these ducklings were examined by DNA dot blot hybridization on the 30th day after inoculation. The results showed that: (1) examination of viral DNA in liver was more sensitive and reliable than estimation of the DNA in serum for detecting DHBV infection in inoculated ducklings; (2) the liver DHBV DNA level did not coincide with the degree of liver hepatitis induced; (3) 21-day-old Chinese ducklings were also susceptible to DHBV infection, the infection rate of this group was 100% (10/10).