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Biomedical subjects

M A Finkelman

Publications and source records attributed to M A Finkelman.

12 recordsLinked to original sources
PubMed2000

Prostatic secretory protein (PSP94) expression in human female reproductive tissues, breast and in endometrial cancer cell lines.

PSP94 (beta microseminoprotein, beta MSP) is one of the three major proteins secreted by the normal human prostate gland. Using reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blotting, PSP94 transcripts were shown in human endometrium, myometrium, ovary, breast, placenta and in the human endometrial cancer cell lines KLE and AN3 CA. Primers used in these studies were specific for human prostate PSP94, and were derived from its flanking non-coding regions. The results were confirmed by sequence analysis of two independently derived clones from normal human breast tissues and the other two from KLE cells respectively. The sequences were identical with the coding sequence of human prostate PSP94 cDNA. Using RNA from the endometrial tissues, two different transcripts of approximately 487 bp, equivalent to prostate PSP94 and approximately 381 bp, corresponding to prostate PSP57, its alternately spliced form, were amplified by RT-PCR. Human ovary, breast, placenta and endometrial cancer cell lines (KLE, AN3 CA), however, showed only the full length, approximately 487 bp, PSP94 transcript. We further demonstrated by in situ hybridization that PSP94 mRNA is expressed specifically in the glandular epithelial cells, and not in the stroma of both the human endometrial and breast tissues. Further, using image analysis of in situ hybridization data, the levels of PSP94 mRNA in the cycling endometrial tissues and in breast confirmed the differential levels of expression in the cycling endometrium (P<0.005). This study distinctly demonstrated significant expression of PSP94 mRNA in human uterine, breast and other female reproductive tissues as well in the endometrial cancer cell lines, suggesting that it may have a role in these tissues as a local autocrine paracrine factor.

Animals↗
PubMed1999

Prostate secretory protein (PSP94) suppresses the growth of androgen-independent prostate cancer cell line (PC3) and xenografts by inducing apoptosis.

BACKGROUND: PSP94 (prostate secretory protein of 94 aa; also called PIP), one of the predominant proteins secreted into the seminal fluid, was proposed as an independent diagnostic/prognostic marker for prostate cancers. It was also shown to inhibit rat prostate cancer growth. In this study, we investigated the effect of purified PSP94 on the growth of androgen-independent human prostate cancer cells (PC3) and its potential mechanism of action. METHODS AND RESULTS: PSP94, in a dose- and time-dependent manner, inhibited the growth of PC3 cells. The protein demonstrated a stronger inhibitory effect on the colony-forming ability of PC3 cells in soft agar. A daily injection of PSP94 at 5 microg/kg/body weight resulted in a 50-60% inhibition in the growth of PC3 xenografts in athymic mice. PC3 cell growth inhibition by PSP94 resulted from cell death characteristic of morphological apoptosis, which was confirmed by dual fluorescence microscopy, electron microscopy, and DNA fragmentation assays. Mechanistic studies indicated that PSP94 enhanced the expression of proapoptotic protein Bax without affecting Bcl-2 levels. CONCLUSIONS: This study suggests that PSP94 may represent a novel, apoptosis-based, antitumor agent applicable to the treatment of hormone-refractory human prostate cancers.

Androgens↗
PubMed1998

Identification of binding proteins for PSP94 in human prostate adenocarcinoma cell lines LNCaP and PC-3.

BACKGROUND: Prostatic secretory protein of 94 amino acids (PSP94) is one of the predominant proteins found in human seminal fluid. Limited information is available regarding a physiological function for PSP94. An important step in the elucidation of this function is the determination of the mechanism of interaction of PSP94 with potential cellular targets. METHODS: Equilibrium binding assay was employed to demonstrate specific binding of biotinylated-PSP94 to the LNCaP and PC-3 cell lines. Binding proteins were partially purified by PSP94 affinity-chromatography from LNCaP, PC-3 cells, and prostate tissues. RESULTS: Binding of biotinylated-PSP94 to LNCaP and PC-3 cells was saturable and time and temperature dependent. The binding could be specifically competitively inhibited by unlabelled PSP94. Two types of PSP94 binding sites with distinct affinity (Kd) and density (Bmax) were determined by Scatchard analysis for each of the two cell lines. For the LNCaP cells, these values were Kd 1 = 0.75 nM and Bmax1 = 300 fmol/mg protein and Kd 2 = 4.5 nM, Bmax2 = 780 fmol/mg protein, respectively. Similar affinity and density results were obtained for PC-3 cells: Kd 1 = 0.83 nM, Bmax1 = 250 fmol/mg protein, and Kd 2 = 5.0 nM, Bmax2 = 700 fmol/mg. The binding of biotinylated-PSP94 to the LNCaP cells was competitively inhibited by the partially purified proteins. Analysis of these proteins SDS-PAGE showed three main bands and the molecular weights of these three bands were approximately 180, 100 and 60 kD, respectively. CONCLUSIONS: The data showed the presence of specific binding proteins to the PSP94 in LNCaP, PC-3 cells, and prostate tissue.

Adenocarcinoma↗
PubMed1998

Detection of PSP94 and its specific binding sites in the prostate adenocarcinoma cell line LNCaP.

PURPOSE: To evaluate the expression of prostate secretory protein of 94 amino acids (PSP94) and PSP94 binding proteins in the LNCaP cell line. MATERIALS AND METHODS: The reverse-transcription polymerase chain reaction (RT-PCR) and Southern blot hybridization were employed to assay the expression of PSP94. Immunoprecipitation with specific polyclonal antibodies was used to detect PSP94 secreted by the LNCaP cells. The binding proteins were assayed by equilibrium binding assays. RESULTS: PSP94 was expressed and secreted in the LNCaP cells. As well as, LNCaP cells expressed surface membrane proteins capable of binding PSP94 in a specific and saturable manner. Exposure of LNCaP cells to exogenous PSP94 resulted in the up-regulation of PSP94 binding sites, indicating functional interactions for PSP94 and its receptor in this cell line. CONCLUSION: The expression of PSP94 and its receptors may be partially regulated by an autocrine pathway in the LNCaP cell line.

Adenocarcinoma↗
PubMed1996

A new scalable purification procedure for prostatic secretory protein (PSP94) from human seminal plasma.

A simple three-step procedure for the purification of native prostate secretory protein (PSP94) from human seminal plasma is described. The steps are ammonium sulfate fractionation followed by a Macro-Prep S support (cation) flowthrough process and the final Macro-Prep high Q support (anion exchange) chromatography using two step-gradient elution. The benefits of this procedure lie in its simplicity, speed, and relatively inexpensive materials, thus providing advantages over the previously reported schemes. The purity of the product as judged by single band on SDS-polyacrylaminde gel electrophoresis was equivalent to that attained by analytical HPLC anion exchange procedure. Yields were in the range of 18-25 mg highly pure PSP94 per 50 ml of seminal plasma. The desalted, lyophilized, purified PSP94 sample was characterized by SDS-PAGE, Western blot, and N-terminal sequencing. All parameters tested confirm its identity. Preliminary data show that this procedure is suitable for a large-scale production. The direct quantitation of PSP94 by SDS-PAGE and densitometric image analysis at various purification steps for evaluating the recovery of PSP94 is described. The results obtained show that this is an efficient strategy for preparation of highly purified native PSP94.

Blotting, Western↗
PubMed1995

Alternative splicing of PSP94 (prostatic secretory protein of 94 amino acids) mRNA in prostate tissue.

While performing reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of total mRNA from prostate cancer specimens, two forms of PSP94 cDNA were detected. RT-PCR products were analysed by Southern blotting and probing with exon-specific oligonucleotides. In the short form of PSP94 mRNA, designated as PSP57, exon III was found to be deleted. The two mRNA forms were confirmed by cloning and sequencing of the RT-PCR products and were found to result from alternative splicing. The alternatively spliced form, PSP57, was characterized by sequence analysis. PSP94 and PSP57 possess identical exons I and II, including identical secretion signal peptide and the 5' untranslated sequences. PSP57 has a frame-shifted exon IV and encodes a putative 57 amino acid protein with a novel, highly basic C-terminus of 41 amino acids. PSP57 mRNA was detected in other urogenital tissues (kidney, bladder) and in most tumor cell lines tested, but was not detectable in other tissues such as breast and lung. In prostate tumor cell lines, PSP57 mRNA was aberrantly spliced and localized in the nuclear fraction of the cell. Our results suggest the possible existence of a novel PSP protein that originates from alternative splicing of PSP94 mRNA in urogenital tissues.

Aged↗
PubMed1991

Construction, binding properties, metabolism, and tumor targeting of a single-chain Fv derived from the pancarcinoma monoclonal antibody CC49.

CC49 is a "second generation" monoclonal antibody to B72.3, which reacts with the pancarcinoma antigen TAG-72. CC49 has been shown to efficiently target human colon carcinoma xenografts and is currently being evaluated in both diagnostic and therapeutic clinical trials. We describe here the construction and characterization of a recombinant single-chain Fv (sFv) of CC49. The sFv was shown to be a Mr 27,000 homogeneous entity which could be efficiently radiolabeled with 125I or 131I. Comparative direct binding studies and competition radioimmunoassays using CC49 intact IgG, F(ab')2, Fab', and sFv revealed that the monomeric CC49 Fab' and sFv had relative binding affinities 8-fold lower than the dimeric F(ab')2 and intact IgG. Nonetheless, the 131I-labeled sFv was shown to bind biopsies of TAG-72-expressing tumors. Metabolism studies in mice, using radiolabeled CC49 IgG, F(ab')2, Fab', and sFv, demonstrated an extremely rapid plasma and whole body clearance for the sFv. CC49 sFv plasma pharmacokinetic studies in rhesus monkeys also showed a very rapid plasma clearance (T1/2 alpha of 3.9 min and T1/2 beta of 4.2 h). Tumor targeting studies with all four radiolabeled Ig CC49 forms, using the LS-174T human colon carcinoma xenograft model, revealed a much lower percentage injected dose/g tumor binding for the CC49 monomeric sFv and Fab' as compared to the dimeric F(ab')2 and intact IgG. However, tumor:normal tissue ratios (radiolocalization indices) for the sFv were comparable to or greater than those of the other Ig forms. High kidney uptake with 125I-labeled Fab' and F(ab')2 was not seen with 125I-sFv. Gamma scanning studies also showed that 131I-CC49 sFv could efficiently localize tumors. The CC49 sFv may thus have utility in diagnostic and perhaps therapeutic applications for a range of human carcinomas.

Animals↗
PubMed1991

Construction and characterization of a single-chain catalytic antibody.

The antigen-binding (Fab) fragment of the catalytic monoclonal antibody NPN43C9 has recently been cloned by using bacteriophage lambda. By inserting the variable regions of this Fab coding sequence into a (NH2)-VL-linker-VH-(COOH) construct (where VL and VH represent the heavy and light chain variable regions), we have assembled a recombinant gene encoding a catalytic single-chain antigen-binding protein. This protein has been expressed in Escherichia coli and exhibits the same catalytic parameters as the parent monoclonal antibody NPN43C9. Single-chain forms of catalytic antibodies may prove valuable for structural and site-directed mutagenesis studies as well as for large-scale applications of catalytic antibodies.

Amino Acid Sequence↗
PubMed1982

Simplified microassay for pullulan synthesis.

A simple radiometric microassay for extracellular polysaccharide elaboration by yeast-like cells of Aureobasidium pullulans was developed, based upon a procedure originally described by Catley (FEBS Lett. 20:174-176, 1972). Incorporation of [C]glucose into pullulan was linear with respect to time and cell dose. The pH and temperature optima for elaboration were 5.3 and 30 degrees C, respectively. Polysaccharide elaboration declined linearly with culture age.

Journal Article↗
PubMed1982

Pullulan Elaboration by Aureobasidium pullulans Protoplasts.

Protoplasts of Aureobasidium pullulans are capable of producing pullulan. Biosynthesis of the polymer pullulan required induction with kinetics similar to those of whole cells. The protoplasts also produced a heteropolysaccharide component containing mannose, glucose, and galactose. The relative proportions of the pullulan and heteropolysaccharide fractions were a function of glucose concentration, with the pullulan content of the total polysaccharide rising from 20% at 2.5 mM glucose to 45% at 20 mM glucose. Elaboration of pullulan by both cells and protoplasts was sensitive to 0.6 M KCl, which was present as the osmotic stabilizer in protoplast experiments. The presence of KCl resulted in a shift in the pH optimum to a more acidic value. The molecular weight of the protoplast-derived pullulan was sharply reduced from the molecular weight of the whole-cell-derived product. Exposure of the protoplasts to proteolytic enzymes had no effect on polysaccharide elaboration.

Journal Article↗