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E Lovelace

Publications and source records attributed to E Lovelace.

14 recordsLinked to original sources
PubMed1993

PR1--a monoclonal antibody that reacts with an antigen on the surface of normal and malignant prostate cells.

BACKGROUND: The principal treatment for prostate cancer is surgery; prostate cancer is resistant to the common anticancer drugs. The only useful therapy for metastases involves diminishing testosterone levels by orchiectomy or administration of drugs, either of which may increase survival time. One approach to prostate cancer treatment is to use a monoclonal antibody (MAb) to target cytotoxic substances to these cancer cells. The MAbs available either do not react uniformly with prostate cancer cells or react with normal tissues. Thus, a new MAb is needed. PURPOSE: The goal of this study was to isolate an MAb that reacts with an antigen present on the surface of prostate cancer cells. METHODS: A strain of prostate cancer cells was isolated from a prostate cancer specimen, grown for 2-4 weeks in short-term culture, and used to immunize BALB/c mice. Hybridomas were then prepared by using spleen cells from the immunized mice. One hybridoma produced an MAb (PR1) that reacted with prostate cancers. RESULTS: MAb PR1 is an IgMK subtype that reacts uniformly with the surface of most (25 of 26) adenocarcinomas of the prostate. It also reacts with the surface antigen on normal prostate epithelial cells and on cells from benign prostatic hyperplasia. MAb PR1 reacts with a limited number of normal tissues including a subset of principal cells located in the collecting ducts of the kidney. CONCLUSION: We conclude that MAb PR1 reacts with a differentiation antigen present in normal prostate and that this antigen continues to be expressed on almost all adenocarcinomas of the prostate. IMPLICATIONS: This antibody may be useful for the diagnosis of or therapy for prostate cancer.

Adenocarcinoma↗
PubMed1992

Effect of P-glycoprotein expression on sensitivity to hormones in MCF-7 human breast cancer cells.

BACKGROUND: Data obtained from studies of primary human breast cancers and established cell lines indicate that overexpression of the MDR1 gene (also known as PGY1) is associated with decreased expression of steroid hormone receptors and increased expression of epidermal growth factor (EGF) receptors. Other study results indicate that both progestins and triphenylethylene antiestrogens may be substrates for P-glycoprotein, the product of the MDR1 gene. These findings together suggest an association between overexpression of the MDR1 gene and cross-resistance to progestin and antiestrogen therapies. PURPOSE: This study was designed to determine (a) the ability of MDR1 expression to alter tumor sensitivity to hormone therapy and (b) the role of MDR1 expression in expression of functional hormone receptors in human breast cancer. METHODS: We transduced MCF-7 cells with MDR1 complementary DNA, using a retroviral vector directing the constitutive expression of the MDR1 gene. Transduced cells (MCF-7MDR1) were examined for ability to produce P-glycoprotein, expression of steroid hormone receptors, and responsivity to antiestrogens. For comparison, we used MCF-7ADR human breast cancer cells, which overexpress MDR1 and have also lost the requirement for 17 beta-estradiol supplementation to form tumors in nude mice. We also investigated the level of EGF-R mRNA expression by using a sensitive RNase protection analysis. RESULTS: MCF-7MDR1 cells retained both estrogen receptor and progesterone receptor expression as well as sensitivity to 4-hydroxytamoxifen. Expression of the estrogen-inducible pS2 and EGF receptor genes was similar in parental MCF-7 and transduced MCF-7MDR1 cells. EGF receptor expression was increased, and pS2 expression was lost (undetectable) in MCF-7ADR cells. CONCLUSIONS: The data indicate that overexpression of the MDR1 gene alone confers a multidrug-resistant phenotype, but it does not directly result in either cross-resistance to antiestrogens or a loss of steroid hormone receptor expression. IMPLICATIONS: MCF-7MDR1 cells provide an important model for study of the interactions of cytotoxic drugs, hormones, and the MDR1 glycoprotein in human hormone-responsive breast cancer cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Agents which reverse multidrug-resistance are inhibitors of [3H]vinblastine transport by isolated vesicles.

Resistance of human cancer cells to multiple cytotoxic hydrophobic agents (multidrug resistance) is due to overexpression of the MDR1 gene whose product is the ATP-dependent multidrug transporter, P-glycoprotein. We have previously reported that plasma membrane vesicles partially purified from multidrug-resistant human KB carcinoma cells, but not from drug-sensitive cells, accumulated [3H]vinblastine in an ATP-dependent manner (Horio, M., Gottesman, M.M. and Pastan, I. (1988) Proc. Natl. Acad. Sci. USA 85, 3580-3584). Certain calcium-channel blockers, quinidine, and phenothiazines are able to overcome multidrug resistance in cultured cells. In this work, the effect of these reversing agents on ATP-dependent vinblastine (VBL) transport by vesicles from drug-resistant KB cells has been characterized. Azidopine was the most potent inhibitor of ATP-dependent VBL uptake tested (ID50: concentration of inhibitor such that the transport of vinblastine is inhibited by 50%, less than 1 microM). Verapamil, quinidine, and the tiapamil analogue RO-11-2933 were potent but less effective inhibitors (ID50 less than 5 microM). Diltiazem, nifedipine and trifluoperazine were even less effective. These agents had no effect on Na(+)-dependent and Na(+)-independent L-leucine uptake by the vesicles, indicating that the inhibition of ATP dependent VBL transport by these agents is not a non-specific effect, as might result from leaks in the vesicle membrane. Verapamil, quinidine, azidopine and trifluoperazine increased the apparent Km value of vinblastine transport, suggesting that these agents may be competitive inhibitors of vinblastine transport.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1988

A retrovirus carrying an MDR1 cDNA confers multidrug resistance and polarized expression of P-glycoprotein in MDCK cells.

A full-length cDNA for the human multidrug resistance gene 1 (MDR1) has been inserted into a retroviral vector containing a murine Harvey sarcoma virus from which the viral oncogene was deleted. Ecotropic and amphotropic virus was produced after transfection of this vector into psi-2 and PA-12 packaging cell lines. This virus conferred the full phenotype of multidrug resistance on mouse and human cell lines. Viral titers of up to 2 X 10(5) drug-resistant colonies per ml were observed. Infected cells became resistant to colchicine, vinblastine, doxorubicin, VP16 (etoposide), and puromycin, but not cisplatin, indicating that the presence of the human MDR1 gene is sufficient to cause multidrug resistance. When the dog kidney cell line MDCK was infected with the MDR1 virus, P-glycoprotein was expressed in a polarized manner on the upper surface of the cells, showing that the cloned cDNA also encodes information for polarized expression of P-glycoprotein. The MDR1 virus should be useful for introducing this drug resistance gene into a variety of cell types for biological experiments in vitro and in vivo.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1986

Characterization of a membrane-associated 3,3',5-triiodo-L-thyronine binding protein by use of monoclonal antibodies.

Four mouse hybridoma cell lines have been isolated which secrete antibodies to the membrane-associated thyroid hormone binding protein (Mr 55,000) from human epidermoid carcinoma A431 cells. J6 is rat specific; J2 is human and monkey specific; J8 and J9 have a wider specificity and react with similar thyroid hormone binding proteins (p55) from human, monkey, rat, and hamster. None of these antibodies reacts with mouse cells. J2, J6, and J9 are of the IgG1k class, and J8 is an IgAk antibody. p55 was characterized by using these monoclonal antibodies. It is not posttranslationally processed by glycosylation, phosphorylation, or sulfation. It has a cellular degradation rate t1/2 approximately equal to 3.2 h. Using immunofluorescence and electron microscopic immunocytochemistry, p55 was found to be associated with the lumenal face of the endoplasmic reticulum and nuclear envelope. When cell homogenates were prepared, significant amounts of p55 were released into the 110000g supernatant, indicating that p55 is loosely associated with the endoplasmic reticulum and nuclear envelope.

Animals↗
PubMed1981

Decrease in the levels of nuclear RNA precursors for alpha 2 collagen in Rous sarcoma virus transformed fibroblasts.

We have examined the levels of type I alpha 2 collagen RNA precursors, containing both intron and exon sequences in nuclear RNA preparations of chick embryo fibroblasts (CEF) and of CEF transformed by the Schmidt-Rupin strain of Rous sarcoma virus (RSV). We have used two different fragments of chick alpha 2 collagen genomic DNA as hybridization probes in S1 mapping experiments. Each of these DNA probes contains an entire intron. Our results indicate that the levels of the primary transcript of alpha 2 collagen RNA are much lower in RSV-CEF than in CEF. They suggest, but do not prove that the effect of the transforming protein p60src on the synthesis of alpha 2 collagen is mediated by a transcriptional control mechanism.

Animals↗
PubMed1976

Insulin receptors in normal and transformed fibroblasts: relationship to growth and transformation.

The insulin receptors in normal and transformed lines of mouse Balb/3t3 fibroblasts have been studied. In the normal fibroblasts, the binding of insulin was low in growing cells and increased 2-9 fold in confluent stationary cells. Insulin binding was increased whether growth arrest was due to contact inhibition of growth or serum starvation. When serum-starved cells were stimulated to grow by the addition of fresh serum, insulin binding declined. In cells transformed by simian virus 40, Kirsten, Moloney, and Harvey sarcoma viruses, methylcholanthrene, X rays, or spontaneously, the binding was low, in the same range as growing normal cells. In simian virus 40-transformed cells, insulin binding increased 4 fold as the cells reached higher densities in culture. No relationship to changes in cell size was found. The differences in binding were due to changes in the concentration of the receptors, without changes in their affinity for the hormone.

Blood↗