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B C Liu

Publications and source records attributed to B C Liu.

At least 19 recordsLinked to original sources
PubMed1995

LAK cell mediated apoptosis of human bladder cancer cells involves a pH-dependent endonuclease system in the cancer cell: possible mechanism of BCG therapy.

Intravesical bacillus Calmette-Guerin (BCG) is an effective treatment for superficial bladder cancer. However, its mechanism has been only partially elucidated. We studied whether LAK cell killing of human bladder cancer cells occurs via apoptosis (programmed cell death) or necrosis. Fluorescent dye labeled T24 cells were observed to undergo morphologic changes associated with apoptosis in the presence of LAK cells when analyzed under a fluorescence microscope. Furthermore, analysis of the DNA isolated from the cytotoxic assay confirmed that the LAK cell induced death of the T24 cells occurred via apoptosis. By pretreating the LAK cells with antifibronectin antibodies, we were able to significantly inhibit the LAK cell killing of the T24 cells. The percentage of cytotoxicity was reduced from 50% to 13% (p = 0.001), and the apoptotic pattern seen on agarose gel electrophoresis was significantly diminished. There was no significant change in the viability of the LAK cells following treatment with the antibodies. Endonuclease isolation from human bladder cancer T24 cells demonstrated that these cells express a pH-dependent and not a Ca++/Mg++ dependent endonuclease. Significant degradation of a target DNA was observed only in pH 4 to pH 5.6 buffers containing endonuclease from T24 cells and not in pH 6 to pH 8 buffers containing endonuclease from T24 cells. The presence or absence of Ca++/Mg++ in the various pH buffers did not alter the endonuclease activity. Finally, we demonstrated that death of T24 cells can be induced by altering the intracellular pH of the cells to 5.6 or lower with the proton ionophore nigericin. We conclude that LAK cells induce T24 cells to undergo apoptosis and that this process involves the fibronectin molecule present on the LAK cell membrane. Furthermore, the cleavage postulate that, in vivo, LAK cells activated by IL-2 produced by BCG activated CD4+ cells may induce bladder cancer cells to undergo apoptosis. This may partially explain the mechanism whereby BCG achieves its therapeutic effect.

Antibodies↗
PubMed1994

Collagen gene expression in radiation interstitial pneumonitis.

By using type I and type III collagen cDNA probe and cDNA-mRNA in situ hybridization, we observed the changes of rat lung alpha 1(I) and alpha 1(III) collagen gene expression in radiation interstitial pneumonitis. The results showed that the expressed cell of type I and type III collagen were scattered within the fibroblasts in the thickened interalveolar walls. The type I and type III collagen mRNA content in irradiated animals were higher than those in the controls at 0.5, 1, 2, 3, 6, and 12 months.

Animals↗
PubMed1994

[Alternations of collagen content and collagen gene expression in rat vascular structural remodeling of pulmonary artery induced by hypoxia].

The change of collagen content and procollagen alpha 1 (I), alpha 1 (III) mRNA expression in rat vascular structural remodeling of extrapulmonary artery (EPA) induced by hypoxia were investigated. 72 wistar male rats weighing 200-300g were used and divided into 2 groups: air-breathing group (N group, 39 rats) and hypoxic group (H group, 33 rats exposed to 5000m hypobaric hypoxia for 7 days). Results showed that mPAp, Rv/(Lv+s), the wet, dry weights and hypoxyproline (HP) content in EPA of H group were increased from 2.83 +/- 0.09kPa (mean +/- smean), 0.23 +/- 0.01, 5.2 +/- 0.2mg, 1.7 +/- 0.1mg and 22.3 +/- 1.0 micrograms)/100g BW (body weight) to 4.77 +/- 0.12kPa, 0.43 +/- 0.01, 10.5 +/- 0.5mg, 4.1 +/- 0.2mg and 58.4 +/- 3.4 micrograms/100g BW (body weight) to 4.77 +/- 0.12kPa, 0.43 +/- 0.02, 10.5 +/- 0.5mg, 4.1 +/- 0.2mg and 58.4 +/- 3.4 micrograms/100g (all P < 0.01). Dot Blot and Northern Blot hybridization analyses showed that in EPA of H group procollagen alpha 1(I) and alpha 1(III) mRNAs were increased 154% and 177% (all P < 0.05). Histological study (HE) showed that hypoxia could induce an increase in the wall thickness of EPA, particularly in adventitial thickness of the pulmonary arterial trunk. Electron microscopy revealed the hypertrophied medial smooth muscle cells containing a significant increase in rough endoplasmic reticulum (RER), in extracellular ground, collagen fibers and elastin were increased. In adventitia, the fibroblasts showed both hypertrophy and hyperplasia and surrounding collagen fibers were increased. These studies suggested that fibroblast might play important role in the remodeling of EPA during the early hypoxic pulmonary hypertension and the increase of collagen gene expression might be involved in the mechanism of collagen content and remodeling of EPA induced by hypoxia.

Animals↗
PubMed1994

The effects of tetrandrine (TT) and polyvinylpyridine-N-oxide (PVNO) on gene expression of type I and type III collagens during experimental silicosis.

In the screening tests of drugs for silicosis in our laboratory, we found that TT, a type of alkaloid isolated from Stephania tetrandra, could inhibit the development of experimental silicosis of rats and the synthesis of collagen in rat lung. Chest X-rays of silicotic patients treated with TT for 1-3 years showed obvious changes. The silicotic nodules became smaller and shadows became clearer. PVNO was proved to have anti-silicotic effect on animal and clinically. This presentation reports the effect of them on collagen mRNA. Dot blot results showed that alpha 1 (I) and alpha 1 (III) mRNA levels increased significantly at 60 and 120 days after the rats were exposed to silica dust. The mRNA levels went down at 1 and 3 months after treated by TT and PVNO. In situ hybridization observation revealed that the silver grains of Type I and Type III collagen were scattered within the fibroblasts in cellular nodules and in thickened interstitium of silicosis tissue. The amounts of mRNA silver grains decreased in the lung tissue treated by TT and PVNO. It was suggested that TT and PVNO may inhibit the gene expression of collagen during silicosis.

Alkaloids↗
PubMed1994

Effects of calcium and calmodulin inhibitors on the abnormal proliferation of lung fibroblast.

The effects of alveolar macrophage (Am phi) conditioned media from interstitial lung disease (ILD) patients on fibroblast (FB), and the role of calcium (Ca2+) blockers and calmodulin (CaM) inhibitors on the proliferation of lung FB were studied. We found that the AM phi conditioned media could stimulate FB cell proliferation and this effect could be abolished by Ca2+ blockers and CaM inhibitors. The results indicated that AM phi was in activated state in ILD and released some kinds of cytokines to stimulate the proliferation of FB, and Ca,2+ CaM were partially responsible for these actions.

Bronchoalveolar Lavage Fluid↗
PubMed1992

Abrogation of the invasion of human bladder tumor cells by using protease inhibitor(s).

It was shown previously that invasive human transitional cell carcinoma cell line EJ, but not the noninvasive RT4 cells, can degrade basement membrane laminin and that the degradation of basement membrane laminin was a result of a redistribution of activated cysteine proteinase cathepsin B to the plasma membrane of the invasive EJ cells. Using a modified Boyden chamber and an artificial basement membrane, it was found first that cysteine proteinase inhibitor E-64 can abolish the ability of the EJ cells to invade through the artificial basement membrane to the underside of the filter. Second, E-64 can prevent the degradation of purified human basement membrane laminin by the plasma membrane fraction of invasive EJ cells. Third, E-64 does not affect the ability of the EJ cells to attach to the extracellular matrix nor is the inhibitory dose toxic to the cells when assayed with trypan-blue dye exclusion. However, E-64 does affect the ability of the EJ cells to respond to autocrine motility factor-induced motility. Finally, in an in vivo model, E-64 was not toxic to the animals tested and may have limited the blood-borne metastatic ability of invasive EJ cells in the treated animals. It was concluded that proteinase cathepsin B may be involved in human bladder tumor invasion, in both extracellular matrix degradation and factor-induced cellular motility, and the authors suggested that the use of inhibitor(s) to cysteine proteinases may limit the invasive potential of human bladder cancer cells.

Animals↗
PubMed1992

Bacillus Calmette-Guerin abrogates in vitro invasion and motility of human bladder tumor cells via fibronectin interaction.

Intravesical bacillus Calmette-Guerin (BCG) has been shown to be an effective treatment for superficial transitional cell carcinoma of the bladder (TCC). The mechanisms by which BCG limits tumor cell activity have thus far been unclear. We investigated the interaction between BCG and invasive human TCC cell line EJ in an in vitro invasion assay. We observed that BCG inhibited the invasion of EJ cells through an artificial basement membrane. In terms of the steps involved in tumor cell invasion, i.e. attachment, proteolysis, and motility, BCG was found to limit tumor cell motility. Attachment and proliferation of tumor cells were not affected by BCG. The effects of BCG on tumor cell migration were mediated by fibronectin (FN), a basement membrane glycoprotein component. Abrogation of BCG-FN-tumor cell interactions with anti-FN antibodies eliminated the ability of BCG to block tumor cell invasion. Fibronectin appears to link BCG and tumor cells via independent FN binding receptors to separate domains of the FN molecule. The molecular mechanism by which BCG may limit tumor cell motility may be its ability to protect against the formation of specific FN sequences as a result of protease cathepsin B digestion. A 31 kD and 27 kD FN band were absent from purified or tumor cell associated cathepsin B digestion when incubated in the presence of BCG, but present in the absence of BCG. Furthermore when purified from SDS polyacrylamide gel electrophoresis, the fragments were shown to have motility stimulating activity for the invasive EJ cells. These findings suggest that BCG functions as a potent inhibitor of tumor cell invasion. We conclude that BCG-fibronectin-tumor cell interactions may have a direct influence on the invasive mechanisms, such as motility, of tumor cells.

BCG Vaccine↗
PubMed1992

Biochemistry of bladder cancer invasion and metastasis. Clinical implications.

In bladder cancer, the finding of infiltration signals the capability of a tumor to behave in an aggressive manner and potentially create a life-threatening situation. The ability to invade is carried in the tumor cell's complement of biochemical pathways as well as in its inability to preserve or restore rather than to disrupt normal tissue architecture. What determines the activation and deployment of these biochemical activities is unclear. That they occur, however, and can distinguish aggressive cancers likely to metastasize from cancers whose behavior is benign, is not. Recognizing and identifying these distinctions is an important step in designing new therapies to prevent a tumor's potential aggressive behavior, possibly reverse or at least contain any extensions that have occurred, and ultimately convert a potentially life-threatening situation to one with a more benign prognosis.

Animals↗
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↗