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B C Liu

Publications and source records attributed to B C Liu.

51 records · Page 3Linked to original sources
PubMed1991

Type IV procollagen mRNA regulation: evidence for extracellular matrix/cytoskeleton/nuclear matrix interactions in human urothelium.

The absence of basement membrane components correlates with tumor stage and progression in human bladder cancers. We have previously shown that invasive tumors possess the ability to degrade basement membrane. However, the presence of basement membrane may be affected not only by its degradation, but by its synthesis and deposition as well. Our results in the present study suggest that while the invasive human transitional carcinoma cell line EJ has an increased amount of type IV procollagen mRNA when compared to the non-invasive RT4 cell line, type IV collagen staining is absent in the invasive EJ cells and intensely present in the non-invasive RT4 cells. Moreover, when EJ cells were grown on an artificial basement membrane (Matrigel), type IV procollagen mRNA expression was down-regulated to the levels seen with the non-invasive RT4 cells. We also discovered that the invasive cells, when grown on Matrigel, appeared morphologically different from the same cells grown on plastic tissue cultures. We conclude that a deficient basement membrane in invasive cancer cells may be due not only to active proteolytic activity but also to an abnormal production and deposition of extracellular matrix components. In addition, we also demonstrated that basement membrane components may have a significant effect on epithelial cell morphology and gene regulation, and that any alterations of the extracellular matrix-cytoskeleton-nuclear matrix interactions can lead to altered gene regulations and cell function.

Basement Membrane↗
PubMed1991

Biochemistry of human bladder tumor invasion.

Bladder tumors comprise a spectrum of neoplastic diathesis. Some behave in a benign fashion, and others are highly aggressive and lead rapidly to metastatic disease and death. The metastasizing potential, often described as a sequence of interrelated steps, involve 1) tumor cell adhesion to basement membranes, 2) degradation of basement membranes and underlying connective tissue stroma, and 3) migration of tumor cells through the destroyed stroma into blood and lymphatic vessels. Each of these processes involves the expression of molecular and biochemical factors identified with tumor cells. With better understanding of the molecular basis of these factors, novel prognostic and potential therapeutic agents can be generated and applied to the clinical arena.

Cathepsins↗
PubMed1990

Inhibition of invasion of invasive human bladder carcinoma cells by protein kinase C inhibitor staurosporine.

To study the effect of the protein kinase C (PKC) inhibitor staurosporine on invasion, we selected the invasive human bladder carcinoma cell line EJ. Total PKC activity was more than twofold higher in the EJ cells than in RT4 cells (superficial human bladder carcinoma cells), which do not pass through an artificial basement membrane. There was more PKC activity in the cytosol than in the membrane of EJ cells. Staurosporine, at nontoxic concentrations, inhibited the invasion of EJ cells through an artificial basement membrane in a dose-dependent manner. Staurosporine caused a dose-dependent inhibition of cell motility but did not inhibit cell attachment. Staurosporine represents a new agent for the inhibition of tumor cell invasion and may prove useful in studying the mechanisms responsible for this phenomenon.

Alkaloids↗
PubMed1990

Mechanisms of human bladder tumor invasion: role of protease cathepsin B.

To study the biochemical mechanisms of bladder tumor invasion, we analyzed specimens of invasive transitional cell carcinoma cell line EJ and non-invasive transitional cell carcinoma cell line RT4 which had been implanted into the bladders of nude mice. Using immunoprobes specific to basement membrane laminin, we observed that superficial but not invasive tumors were surrounded by intact laminin. With immunoprobes specific to cathepsin B, a cysteine proteinase which has the ability to degrade laminin, we demonstrated that cathepsin B is localized in discrete cytoplasmic granules in the non-invasive tumors, and in a more diffuse cytoplasmic pattern in the invasive tumors. Subcellular fractionation followed by immunoblot analysis and enzymatic analysis confirmed that the invasive EJ cells had active cathepsin B localized to its plasma membrane, while non-invasive RT4 cells had cathepsin B confined to lysosomes. Furthermore, immunoblot analysis revealed that invasive EJ cells had the mature form of cathepsin B with a molecular weight of 25 kD, while non-invasive RT4 cells had predominantly precursor forms with molecular weights between 30 and 35 kD. In vitro degradation assays with plasma membrane fractions isolated from invasive EJ cells and non-invasive RT4 cells demonstrated that the plasma membrane of EJ cells but not that of the RT4 cells had the ability to degrade purified laminin, and that the degradative products were similar to those obtained with purified cathepsin B. We conclude that invasive tumor cells have enhanced cathepsin B in their plasma membranes which may be used to degrade basement membrane components such as laminin and thereby facilitate tumor invasion.

Animals↗
PubMed1989

The effect of gamma irradiation on injectable human amnion collagen.

The effect of gamma irradiation on the physicochemical properties of injectable human amnion collagen was investigated. Pepsin-extracted human amnion collagen was purified, reconstituted, and irradiated with varying doses of gamma irradiation (0.25 Mrads to 2.5 Mrads). Gamma irradiation had a significant impact on the physical characteristics of the collagen. The neutral solubility of collagen in PBS at 45 degrees C was decreased from 100% for the nonirradiated control sample to 16% for the 2.5 Mrads irradiated sample. SDS polyacrylamide gel electrophoresis also demonstrated the dose-dependent effect of gamma irradiation on collagen cross-links. Electron microscopic observation revealed that even at low irradiation dose (0.25 Mrads), collagen fibril diameter increased. The average diameter was 50 nm for nonirradiated control fibrils, while 4.4 percent of the irradiated collagen fibrils had a diameter greater than 100 nm. Irradiated collagen showed little evidence of damage. Well-preserved cross-striations were found in collagen fibrils at all doses of irradiation. Native amnion collagen irradiated with gamma rays demonstrated a slight increase in resistance to collagenase degradation compared with nonirradiated native collagen samples. Increased resistance to collagenase did not correlate with increasing irradiation dose. After 30 min of incubation at 37 degrees C, both irradiated and nonirradiated collagen was completely digested by collagenase. However, gamma-irradiated collagen did become more sensitive to hydrolysis by trypsin. The higher the irradiation doses used, the greater sensitivity to trypsin was observed. At 0.25 Mrads irradiation only a slight increase was found. No marked differences in amino acid composition were noted among the high dose irradiated, low dose irradiated and control amnion collagen.

Amino Acids↗
PubMed1987

Ras related oncogene protein as a tumor marker in transitional cell carcinoma of the bladder.

An oncogene related protein has been detected in the urine of patients with transitional cell carcinoma (TCC). This is a 55 kilodalton protein (p55) which is immunologically related to the ras oncogene product p21. Sixteen patients with TCC (55%) and none of the controls exhibited high level of p55 expression (greater than or equal to 3X the level of background). There were ten cancer patients (35%) who had 2X the level of background and three patients (10%) who had the level of background. In contrast, there were two non-cancer patients with 2X level of expression (9%) and the remainder (91%) had the background level of p55 expression. The expression of the marker (p55) tends to correlate with tumor grade and stage and is elevated in patients with a history of multiple recurrences. The ras oncogene has been identified in the tissues of a wide variety of cancers and is not a marker which is specific for any single cancer. The identification of its related gene product in the urine may be useful as a marker for TCC.

Antigens, Neoplasm↗
PubMed1987

Detection of onco-fetal bladder antigen in urine of patients with transitional cell carcinoma.

Studies of antigens associated with transitional cell carcinoma were extended by using murine IgM monoclonal antibody E7, developed earlier by this laboratory. These antibodies react preferentially with human bladder tumors and transitional cell carcinoma (TCC) cell line 647V. We now report that monoclonal antibody E7 detected the presence of antigen in midgestational and third trimester amniotic fluids, and in urine of patients with advanced transitional cell carcinoma. Western blot analysis showed that the antigen present in amniotic fluids consists of a sharp band with molecular weight greater than 200 kdaltons. A similar molecular weight pattern was seen with the solubilized membrane of 647V. A sensitive and convenient sandwich ELISA was developed and the urine of patients with bladder cancer was assayed for the presence of the E7 antigen. Antigen was detected in the urine of patients with advanced transitional cell carcinoma but not in the urine of normal adults or in urine from patients with prostate cancer, renal cell carcinoma, or benign prostate hyperplasia. An inhibition enzyme immunoassay was developed with monomeric forms of the E7 antibody and confirmed the presence of antigen in the urine of patients with TCC. We conclude that the E7 antigen is an onco-fetal antigen expressed in patients with transitional cell carcinoma of the bladder.

Antibodies, Monoclonal↗
PubMed1983

Studies on the contents of glycosaminoglycans from lungs of silicotic rats and tetrandrine-treated silicotic rats.

In this report the differences in the total content of glycosaminoglycans (GAG) and in the relative contents of individual GAG among normal rat lung, silicotic rat lung, and tetrandrine (TT)-treated silicotic rat lung were studied. The differences were also observed with the histochemical method. In normal rat lung the content of GAG was 6.35 mg/g dry tissue. The percentage of heparin sulfate (HeS) was higher than the others. The content of GAG in silicotic rat lung was raised much more than that of the normal rat. Percentages of hyaluronic acid (HyA) and dermatan sulfate (DeS) were higher. Percentage of HeS was lower than that of the normal rat. In silicotic lung GAG existed around the collagen fibers and were netlike in shape. After treatment with TT, most of the GAG were seen to be present within the cells. It was proved that TT could inhibit the increase in the content of GAG in silicotic rat lung and could also obstruct the change in the relative contents of individual GAG.

Alkaloids↗
PubMed1982

[Proteoglycan].

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Animals↗
PubMedDate not supplied

Biology of metastasis: clinical implications.

Bladder tumor has a spectrum of neoplastic activity. Some behave in a benign fashion, and others are highly aggressive and lead rapidly to metastatic disease and death. The processes of metastasis can be described as a sequence of interrelated steps. The processes involve 1) tumor cell adhesion to basement membranes, 2) the degradation of basement membranes, and 3) the migration of tumor cells through the destroyed stroma into blood and lymphatic vessels. Each of these processes involves the expression of molecular factors unique to tumor cells. With better understanding of the molecular basis of these factors, novel prognostic and potential therapeutic agents can be generated and applied to the clinical arena.

BCG Vaccine↗