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M Liebert

Publications and source records attributed to M Liebert.

At least 55 records · Page 3Linked to original sources
PubMed1991

The A9 antigen associated with aggressive human squamous carcinoma is structurally and functionally similar to the newly defined integrin alpha 6 beta 4.

We previously reported that altered expression of the A9 antigen (defined by monoclonal antibody UM-A9) is a predictive marker of early recurrence and progression of squamous cell carcinoma (SCC). In normal squamous cells A9 expression is limited to the site of contact with the basement membrane in vivo and the culture surface in vitro, whereas aggressive SCCs exhibit loss of polarity and increased intensity of A9 expression. The potential relationship of the A9 antigen to structures known to be involved in cell adhesion was analyzed by immunobiochemical and cell adhesion assays. UM-A9 precipitates a complex of protein chains reminiscent of the alpha and beta heterodimer glycoproteins that characterize the integrin family of extracellular matrix receptors. Proteins were isolated from A9-positive cells using UM-A9 and well-defined antibodies specific for integrin alpha and beta chains. UM-A9, anti-alpha 6, and anti-beta 4 monoclonal antibodies (mAbs) all precipitated proteins with comparable electrophoretic mobilities. Furthermore, UM-A9 mAb precleared the SCC alpha 6 beta 4 integrin complex isolated with anti-alpha 6 or anti-beta 4 mAbs but not that isolated by anti-beta 1 mAb. The isoelectric points of the A9 complex chains were consistent with those reported for alpha 6 and beta 4. Three of the polypeptide chains (140, 175, and 205 kDa) precipitated by UM-A9 showed peptide homology to one another and to the beta 4 chain precipitated by mAb 439-9B. The A9/alpha 6 subunit is composed of 125- and 30-kDa chains and was distinguished from beta 4 and beta 1 chains by its peptide map and isoelectric point. UM-A9 binds to an epitope common to the beta 4 subunits since in pulse-chase analysis the beta 4 species are precipitated at an early time point, whereas detection of alpha-subunit synthesis is detected during assembly of the mature complex. Immunoprecipitation and preclearing experiments demonstrated that in SCC the alpha 6 subunit is associated primarily with the beta 4 species and not with the 130-kDa beta 1 subunit. In cell adhesion assays on extracellular matrix proteins, the alpha 6-specific GoH3 mAb inhibited binding of SCC to laminin, suggesting that alpha 6 beta 4 may function as a laminin receptor in SCC. These data and our prior observations showing an association between altered A9 expression and early recurrence in SCC provide the first evidence that altered expression of alpha 6 beta 4 integrin is associated with the clinical behavior of human squamous cell carcinomas.

Antigens, Neoplasm↗
PubMed1991

18F-2-deoxy-2-fluoro-D-glucose uptake into human tumor xenografts. Feasibility studies for cancer imaging with positron-emission tomography.

The positron-emitting glucose analogue 18F-2-fluoro-2-deoxy-d-glucose (FDG) was evaluated for its accretion into the following subcutaneous human tumor xenografts in nude mice: B-cell lymphoma (Namalwa or Raji), ovarian carcinoma (HTB77), colon cancer (SW948), choriocarcinoma (BEWO), bladder cancer (UM-UC-2), renal cell carcinoma (UM-RC-3), neuroblastoma (Mey), melanoma (HTB63), and small cell lung carcinoma (NCI69). Two hours postinjection, tumor uptakes ranged from 0.027 (colon cancer) to 0.125% kg injected dose/g (melanoma); and was greater than 0.085 in the Namalwa lymphomas and the renal cell carcinomas. Tumor-blood ratios of up to 23:1 were seen 2 hours postinjection (melanoma) with a mean tumor-blood ratio for all tumors of 12.3 +/- 1.8. Uptake in the other tumors was intermediate. When evaluated, tumor uptake was slightly greater at 1 than at 2 hours postinjection, although target-background ratios were generally higher at 2 hours postinjection. This compound, FDG, may have broad applicability as a tracer for positron-emission tomographic imaging of many human malignancies.

Animals↗
PubMed1991

The expression of epidermal growth factor receptor on human bladder cancer: potential use in radioimmunoscintigraphy.

Monoclonal antibody 425, which binds to an extracellular domain of the epidermal growth factor receptor, was used to evaluate the expression of this antigen on bladder cancer cells. Epidermal growth factor receptor was found on all bladder cancer cell lines tested. Immunoperoxidase staining of fourteen invasive human bladder cancers with monoclonal antibody 425 demonstrated that ten showed strong staining, one showed weak staining and three were negative. Five noninvasive tumors were similarly examined. Four of these were negative and one showed weak staining. Biodistribution experiments with human bladder tumor xenografts in athymic nude mice using radiolabeled monoclonal antibody 425 and an isotype matched control antibody demonstrated specific tumor localization at five and seven days following antibody injection. Successful imaging of a human bladder tumor xenograft was achieved five days post antibody injection. These data confirm that epidermal growth factor receptor expression correlates with bladder cancer stage and suggests that epidermal growth factor receptor may serve as a target antigen for radioimmunoscintigraphy.

Animals↗
PubMed1991

Uptake of 2-deoxy, 2-(18F) fluoro-D-glucose in bladder cancer: animal localization and initial patient positron emission tomography.

An orthotopically transplanted, locally metastasizing rat bladder tumor model was developed to evaluate the extent of uptake of fluoro-deoxy-glucose (FDG) in bladder cancer. Significant uptake of FDG in localized bladder tumors in rats was shown, with an average tumor-to-blood ratio of 39 at 2 hours after intravenous FDG administration. Metastases (3 nodal and 1 peritoneal) also showed significant uptake of FDG, with an average metastasis-to-blood ratio of 21.7, and tumor involved-to-normal lymph node ratio of 5.3. Because FDG is excreted in the urine, urinary FDG potentially could prevent the use of FDG/positron emission tomography (FDG/PET) scanning for localized bladder cancer. Bladder lavage successfully reduced the retention of FDG in the normal rat bladder, with an estimated uptake ratio of tumor-to-normal bladder of 13.1 after 5 ml. saline irrigation. Based on these data, we performed an FDG/PET scan of a patient with biopsy proved recurrent intravesical bladder cancer after radiation therapy. Computerized tomography (CT) of the pelvis showed abnormalities consistent with radiation scarring and extravesical tumor. Due to the scarring, the extent of tumor growth could not be determined. The patient also had pulmonary opacities seen on chest radiography. The FDG/PET scan of this patient showed significant extravesical uptake in the pelvis, confirming the abnormality noted on CT. Good images of the clinically apparent metastases in the chest also were obtained. These preliminary data indicate that FDG/PET imaging of bladder cancer is feasible and it may provide new information for the diagnosis and staging of patients with bladder cancer.

Animals↗
PubMed1991

The uptake and efflux of doxorubicin by a sensitive human bladder cancer cell line and its doxorubicin-resistant subline.

The uptake and efflux of doxorubicin (Dox) were investigated in a human bladder cancer cell line (UM-UC-6) and in a multi-drug resistant (mdr) subline (UM-UC-6Dox). Unlike previous reports, the initial uptake kinetics of Dox, and its accumulation and retention to steady-state were modelled mathematically. Cells were incubated with Dox and the amount of Dox in the cellular and medium phases was measured by a specific HPLC method. When monitored for 1 min from 0.02 microM to 25 microM Dox, the uptake was very rapid but was significantly faster in the resistant cell line. The initial rate of uptake at t = 0 followed Michaelis-Menten kinetics yielding Vmax values (the maximal rate of uptake) of 15.0 +/- 1.7 and 12.9 +/- 1.2 nmol/10(6)/min and Km (rate at Vmax/2) of 25.2 +/- 4.7 and 16.4 +/- 2.9 microM for UM-UC-6 and UM-UC-6Dox, respectively. There was no metabolism of Dox by keto-reduction or reductive hydrolysis. At 1.0 microM the uptake of Dox to steady-state was biexponential but there was no difference in total cellular Dox concentration between the two cell lines at equilibrium. A 3 compartment sequential closed model was fitted yielding significantly different values for the intercompartmental and hybrid rate constants, indicating altered intracellular distribution in resistant cells. Verapamil (10 microM), trifluoperazine (10 microM) or Tween 80 (0.005%) had no effect on the uptake or efflux of Dox. The UM-UC-6Dox line appeared to show atypical mdr characteristics since net drug accumulation was not lowered and classic P-glycoprotein inhibitors were not effective. The primary mechanism of Dox resistance is not enhanced metabolism or lowered intracellular concentrations.

Chromatography, High Pressure Liquid↗
PubMed1991

Effect of verapamil on the uptake and efflux of etoposide (VP16) in both sensitive and resistant cancer cells.

The effect of calcium antagonist verapamil on the uptake and efflux of Etoposide (VP16), a semi-synthetic derivative of podophylotoxin and a broad spectrum antineoplastic agent, has been investigated and compared in sensitive (UM-UC-2) and resistant (UM-UC-9) human bladder cancer cells, and L1210 leukemia cells, by using both radioisotope (3[H]-VP16) liquid scintillation and high performance liquid chromatography assay with electrochemical detection. The uptake of VP16 was rapid in all three cell lines, showing an initial rapid linear phase followed by a second slower phase, but at steady state the ratios of intracellular to extracellular VP16 concentrations were only 0.004-0.006. No significant difference in drug uptake was observed in sensitive UM-UC-2 and resistant UM-UC-9 cells at all concentrations studied. Verapamil at a concentration of 10 microM enhanced the intracellular VP-16 levels in all sensitive and resistant cell lines. The increments were 21.5% for UM-UC-2, 11.8% for UM-UC-9, and 31.0% for L1210 cells after 30 minutes incubation with 1 microM VP16. A slower efflux of VP16 was observed in verapamil treated cells in all three cell lines. There was a small increase in the nonexchangeable components in verapamil treated cells, although only 5-10% of VP16 was retained. No peak other than that of VP16 was detected in the HPLC chromatogram of extracts from both cell pellet and influx or efflux medium.

Animals↗
PubMed1991

Depletion of c-myc with specific antisense sequences reverses the transformed phenotype in ras oncogene-transformed NIH 3T3 cells.

ras oncogene-transformed NIH 3T3 cells expressing glucocorticoid-inducible antisense c-myc cDNA transcripts at levels sufficient to deplete c-myc protein lost their transformed morphology and the ability to grow in soft agar; their ability to form tumors in nude mice was also impaired. These changes were dependent on the continuous expression of the antisense sequences. No major effects on plating efficiencies, growth rates in monolayer culture, or immortalization were observed in the revertant cells, indicating that the observed effects were not a toxic consequence of c-myc protein depletion. Transfection with the same vector expressing c-myc in the sense orientation or other control vectors had no effect on transformation. These results suggest that a certain minimum level of expression of c-myc is required for the maintenance of ras transformation in NIH 3T3 cells.

Animals↗
PubMed1991

Evaluation of a new bladder tumor marker.

Two monoclonal antibodies have been developed that bind to a shed bladder tumor-associated antigen. Preliminary data have demonstrated that antigen-positive tumors shed detectable amounts of antigen in the urine while antigen-negative tumors do not. This antigen may be differentially metabolized by normal and malignant urothelial cells. Further characterization of this antigen and its evaluation as a urinary marker for antigen positive bladder cancers is continuing.

Antibodies, Monoclonal↗
PubMed1990

Lymphoscintigraphy in melanoma: initial evaluation of a low protein dose monoclonal antibody cocktail.

A low protein dose (73 +/- 10 micrograms total) 131I-labeled monoclonal antibody cocktail made of equal microgram quantities of 225.28S (IgG2a) and 763.24T (IgG1) murine monoclonal antibodies, which bind additively to a high molecular weight antigen of melanoma, was evaluated as a lymphoscintigraphic agent in 17 patients with intermediate to thick (mean Breslow depth, 3.39 +/- 0.64 mm) melanomas or clinical Stage II disease scheduled for nodal dissection. Eleven of the patients were clinically Stage I while 6 were clinically Stage II. 131I antibody cocktail, 258 +/- 10 microCi, was administered s.c. at the site of the primary melanoma or its scar following surgical removal. In eight patients, 63 +/- 8 microCi of 125I nonspecific normal sheep IgG was coadministered s.c. Gamma camera imaging was conducted beginning immediately after and continuing for several days following injection. Surgical resection, weighing, and gamma counting of the draining lymph nodes were undertaken in all patients. On gamma scans, early nodal uptake of antibody was most pronounced and of longest duration in the tumor pathologically positive patients (5 of 7 had visible nodal uptake, 4 of 7 visually stable or rising with time), with the t 1/2 of nodal clearance by gamma scan significantly (P less than 0.05) longer than in the negative patients in whom 4 of 10 showed some, although generally transient (0 of 10 stable or rising), nodal uptake. Scans were not easily interpretable when the injection site was very near the draining nodal group, in part due to the detection of scatter activity from the injection site. In several instances the scan was correct and the clinical examination was incorrect as regards nodal disease. Quantitative analysis of the surgically excised draining nodes showed significantly (P less than 0.001) more 131I anti-melanoma antibody uptake in the 21 tumor-involved nodes [0.01217% injected dose (ID)/node median] than in the 512 tumor-negative nodes (0.00051% ID/node median). Median percentage ID/g of anti-melanoma antibody in tumor-involved nodes was significantly greater (P less than 0.01) than in tumor-negative nodes (0.01984 versus 0.003215% ID/g). 125I-labeled nonspecific antibody did not accumulate significantly more in the tumor-involved nodes on a per node or per g basis in the 283 of 533 nodes studied using the dual-label approach (0.0036 versus 0.00092% ID/g). These data demonstrate that by external imaging and by tissue counting that a radiolabeled anti-melanoma monoclonal antibody cocktail can specifically accumulate to melanoma-involved lymph nodes following s.c. administration.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

Comparison of antigen expression on normal urothelial cells in tissue section and tissue culture.

Antigenic characterization of urothelial cells cultured from normal adult ureter was performed. These cells were cultured using a simplified isolation and culture technique and a commercially available serum-free medium. The cells growing in these cultures had epithelioid morphology and normal quantities of DNA. The antigen expression on these cultured normal urothelial cells was evaluated using a panel of monoclonal antibodies: 5G6.4, AN43, URO-5, anti-keratin and anti-blood group antibodies, and 425 (anti-epidermal growth factor receptor). Lower levels of anti-A and AN43 binding on cultured cells were observed than are seen on urothelial cells in sections of normal ureter, while the binding of anti-blood group H, 5G6.4, and URO-5 was unchanged. Binding of anti-epidermal growth factor receptor antibody 425 was improved if the cells were grown in medium lacking epidermal growth factor. These results confirm the urothelial origin of these cultured urothelial cells but indicate that some antigenic differences between cultured normal urothelial cells and urothelial cells in situ in the normal ureter exist.

ABO Blood-Group System↗
PubMed1990

Fibronectin distribution in normal and malignant urothelium.

Fibronectin is a glycoprotein that mediates the attachment of BCG to the murine bladder. To assess the potential role of fibronectin on bladder cancer cells as a specific substrate for BCG binding in man, a semi-quantitative method was employed to evaluate the presence of fibronectin on normal urothelium and bladder cancer. Monoclonal anti-fibronectin binding to normal and malignant urothelial tissues was evaluated by an immunoperoxidase assay. Human tumor cell lines were evaluated with mixed hemadsorption and immunoperoxidase assays. In both systems, immunoreactive fibronectin had low expression on unfixed normal and malignant urothelium. With fixation, immunoreactive fibronectin decreased on supporting stroma and increased in normal and malignant urothelium. Fibronectin distribution did not show tumor specificity either with fixed or unfixed specimens.

BCG Vaccine↗
PubMed1990

Products of cells from gliomas: VIII. Multiple-well immunoperoxidase assay of immunoreactivity of primary hybridoma supernatants with human glioma and brain tissue and cultured glioma cells.

To test the feasibility of primary screening of hybridoma supernatants against human glioma tissue, over 5000 combinations of hybridoma supernatants with glioma tissue, cultured glioma cells, and normal central neural tissue were screened with a new multiple-well (M-well) screening system. This is an immunoperoxidase assay system with visual endpoints for screening 20-30 hybridoma supernatants per single microscope slide. There were extensive differences between specificities to tissue and to cultured glioma cells when both were screened with M-wells and when cultured cells were screened with standard semi-automated fluorescence. Primary M-well screening with glioma tissue detected seven hybridoma supernatants that specifically identified parenchymal cells of glioma tissue and that were not detected with cultured cells. Immunoreactivities of individual supernatants for vascular components (nine supernatants), necrosis (five supernatants), and nuclei (three supernatants) were detected. Other supernatants bound multiple sites on glioma tissue and/or subpopulations of neurons and glia of normal tissue. The results show that primary screening with glioma tissue detects a number of different specificities of hybridoma supernatants to gliomas not detected by conventional screening with cultured cells. These are potentially applicable to diagnosis and therapy.

Antibody Specificity↗
PubMed1990

Direct stereotactic intracerebral injection of monoclonal antibodies and their fragments: a potential approach to brain tumor immunotherapy.

Delivery of monoclonal antibodies (Mab) to brain tumors is restricted by the blood:brain barrier. To circumvent this problem, we studied direct stereotactic injection of the Mab into the brain. An anti-melanoma intact Mab and its Fab fragments, which do not react with normal rat brain, were radioiodinated and injected either intracerebrally (IC) or intravenously (IV) into rats. At 5 days after injection, IC delivery of intact antibody was 101 times higher than IV delivery. The ratio of radioantibody in injected cerebrum:blood was 14:1. With IC delivered Fab fragments, the radioantibody ratio in injected cerebrum:blood was 242:1 at 5 days after IC injection, with a 680-fold delivery advantage over IV injection. These data demonstrate a dramatic regional delivery advantage for intact Mab and especially for Fab fragments injected directly into the brain. This route of Mab delivery may have therapeutic potential for brain tumors.

Animals↗
PubMed1989

Identification by monoclonal antibodies of an antigen shed by human bladder cancer cells.

The reactivities of two anti-bladder cancer monoclonal antibodies, AN43 and BB369, were characterized. AN43 and BB369 reacted with a majority (greater than 50%) of bladder cancer tissue sections tested by immunoperoxidase staining. When tested against a panel of 27 normal human tissues, AN43 and BB369 reacted only with urothelium and stomach. AN43 and BB369 showed identical binding patterns and competed for binding on bladder cancer cells, suggesting that the two antibodies react with identical or spatially close epitopes. Bound BB369 antibody was rapidly shed from the surface of viable UM-UC-9 human bladder cancer cells. The antigen was found in spent tissue culture medium from the UM-UC-9 human bladder cancer cell line. AN43 and BB369 define a shed bladder tumor-associated antigen with limited distribution on normal tissues. The antigen is different from bladder tumor-associated antigens defined by other monoclonal antibodies and may be useful for the diagnosis and follow-up of patients with bladder cancer.

Antibodies, Monoclonal↗
PubMed1989

Improved radiolabeled monoclonal antibody uptake by lavage of intraperitoneal carcinomatosis in mice.

The effect of peritoneal lavage with saline on tumor and systemic uptake of intraperitoneally administered tumor-specific (131I-5G6.4) and nonspecific (125I-UPC-10) radiolabeled monoclonal antibodies was evaluated in a nude mouse model of human intraperitoneal ovarian carcinomatosis (IP3 model). Peritoneal lavage at 2 or 6 hr postintraperitoneal antibody injection significantly improves intraperitoneal tumor/nontumor uptake ratios of specific antibody apparently by limiting systemic exposure to antibody. This enhancement tends to be more dramatic if lavage is performed within 2 hr, rather than 6 hr, of intraperitoneal antibody administration, though both times result in significant improvements in target/background ratios over no lavage. Twenty-four-hour tumor/nontumor ratios for specific antibody 5G6.4 generally are 1.5-fourfold higher following lavage than those achieved in control animals, without decreasing absolute tumor uptake of specific radiolabeled antibody. By contrast, nonspecific antibody UPC-10 binding is lower in tumor and normal tissues following lavage, with no lavage-induced improvement in tumor/nontumor ratios seen. Peritoneal lavage is a simple method to allow for specific antibody binding to accessible intraperitoneal tumors yet to limit systemic exposure thus increasing the therapeutic margin. This method may have considerable applicability in the enhancement of intraperitoneal immunoconjugate delivery to intraperitoneal tumors.

Animals↗
PubMed1988

The intraperitoneal delivery of radiolabeled monoclonal antibodies: studies on the regional delivery advantage.

The i.p. delivery of murine monoclonal antibody was compared with i.v. delivery in normal mice and rats, in normal nude mice and in those with i.p. human ovarian carcinoma xenografts. In normal rats, all classes of antibodies and antibody fragments evaluated were cleared from the peritoneal cavity at comparable rates. The regional delivery (Rd1) advantage to the peritoneal cavity following i.p. delivery was thus most dependent on the rate of clearance of the antibody or fragment from the blood stream. Determining the exact i.p. delivery advantage was problematic due to the difficulty in reliably obtaining peritoneal fluid later than 9-10 h after i.p. injection in normal animals. During the first 9 h following i.p. injection, the Rd(0-9/0-9) was, for a murine IgG2ak Fab greater than F(ab')2 greater than IgG (at 13.6 greater than 10 greater than 7.9). Two murine IgMs evaluated differed in Rd(0-9) at 27.1 and 9.2 respectively. When blood levels were extrapolated to infinity, these Rd (0-9/affinity) values were considerably lower with the Fab having the highest Rd at 4.67. The i.p. Rd advantage was almost solely due to the i.p. antibody levels seen in the first 24 h after injection, as after that time, blood levels become comparable to those seen following i.v. injection. Normal tissues obtained at sacrifice 5-7 days after i.p. injection. Normal tissues obtained at sacrifice 5-7 days after i.p. or i.v. injection in rats showed comparable levels of radioantibody activity, whether the injection was i.p. or i.v. (except for higher diaphragmatic levels following i.p. delivery). In nude mice with i.p. human-derived ovarian tumors, intact IgG clearance from the peritoneal cavity to the blood was considerably slower than in normal animals, and early i.p. tumor uptake of specific antibody was significantly higher than that following i.v. antibody delivery. With higher early tumor uptake and lower systemic exposure, early tumor/nontumor ratios were significantly greater than those for i.v. delivery, though not beyond 48 h after i.p. injection. This study demonstrates the pharmacokinetic rationale for i.p. monoclonal antibody delivery, especially for agents cleared rapidly from the blood, such as antibody fragments. In addition, definite i.p. delivery benefit for antibody specific to i.p. tumors in the i.p. ovarian cancer system was shown soon after injection. These data regarding i.p. antibody delivery should be useful in rationally planning diagnostic and therapeutic studies involving the i.p. delivery of unmodified and immunoconjugated monoclonal antibodies.

Animals↗
PubMed1988

Radiolabeled antibodies, albumin and antimony sulfide colloid: a comparison as lymphoscintigraphic agents.

The kinetics of lymph node and systemic uptake of members of three different classes of lymphoscintigraphic agents were studied in normal laboratory rats. 99mTc antimony trisulfide colloid (TcSbC), 99mTc human serum albumin (TcHSA), 125I 5G6.4 (a murine IgG2ak monoclonal antibody), 125I 763.24T (a murine IgG1), and 125I FT166 ( a murine IgM monoclonal) all current or potential lymphoscintigraphic agents, were injected subcutaneously into the hind foot pads of healthy rats. Ipsilateral and contralateral popliteal lymph nodes were sampled up to 4 h post-injection. Subcutaneous injection resulted in far higher nodal uptake for all agents than i.v. delivery with ipsilateral popliteal node/blood ratios 1 h postsubcutaneous injection of: for TcSbC (1900) greater than 125I IgM (497) greater than TcHSA (72) greater than 125I Intact IgG2a or 125I IgG1 at approximately 10. Thus, while all agents achieve popliteal node/blood ratios far greater than unity, TcSbc has the greatest absolute and relative nodal accumulation, greater than the 125I IgM monoclonal antibody and TcHSA. Uptake of the intact 125I IgG antibodies is lowest. These data suggest that TcSbC in particular, as well as TcHSA and IgM may be most useful as non-specific nodel imaging agents, while the lower background activity of the IgGs may make targeting specific antigen in nodes more feasible.

Animals↗