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P Vihko

Publications and source records attributed to P Vihko.

At least 91 records · Page 5Linked to original sources
PubMed1992

A difference in the enzyme contents of resorption lacunae and secondary lysosomes of osteoclasts.

The distributions of tartrate sensitive lysosomal acid phosphatase (LAP) and cathepsin L in osteoclasts and the effect of parathyroid hormone (PTH) stimulation on them were investigated by using the protein A-gold method on ultracryosections of rat trabecular bone. LAP was located in association with the ruffled border membrane, in the resorption lacuna, on the mineral phase surrounding the lacuna, and in some primary lysosomes. After PTH treatment, the extracellular and ruffled border membrane associated LAP apparently increased. Heavy gold labelling for cathepsin L was confined exclusively to secondary lysosomes. No labelling was seen in the extracellular resorption lacuna or at the ruffled border. Acceleration of bone resorption by PTH-treatment did not change detectably the distribution or intensity of labelling. This study shows that the enzyme contents of secondary lysosomes and resorption lacunae are different and suggests that LAP is directly involved in extracellular bone degradation whereas the role of cathepsin L is restricted to lysosomes.

Acid Phosphatase↗
PubMed1992

Androgens up-regulate the human prostate-specific antigen messenger ribonucleic acid (mRNA), but down-regulate the prostatic acid phosphatase mRNA in the LNCaP cell line.

To better understand androgen-regulated gene expression in the prostate, we have used Northern blot analysis to study the effects of androgens and other steroid hormones on the steady state levels of several human prostatic mRNAs in the LNCaP cell line. Dihydrotestosterone (40 nM) as well as a synthetic androgen, R1881 (0.1 nM), increased the amounts of prostate-specific antigen (PSA) and human glandular kallikrein mRNAs; at the same time, the level of prostatic acid phosphatase (PAP) mRNA was down-regulated. Incubation of LNCaP cells with medium containing 0.1 or 1 microM R1881 for 3, 7, or 13 days resulted in up-regulation of PSA and human glandular kallikrein mRNAs and down-regulation of PAP mRNA. Thus, the two clinically important prostate-specific marker proteins are inversely regulated in this cell line. The level of human androgen receptor mRNA was also repressed by the androgen treatments. 17 beta-Estradiol and progesterone had effects similar to those of R1881 on gene expression in LNCaP cells. Our results show that the decrease in the amount of secreted PAP and the increase in the amount of secreted PSA caused by androgens and other steroid hormones in the LNCaP cells of epithelial origin are mediated by changes in the levels of the corresponding mRNAs.

Acid Phosphatase↗
PubMed1991

Effects of tumour mass and circulating antigen on the biodistribution of 111In-labelled F(ab')2 fragments of human prostatic acid phosphatase monoclonal antibody in nude mice bearing PC-82 human prostatic tumour xenografts.

We have evaluated the effects of tumour mass and circulating antigen (prostatic acid phosphatase, PAP) on the biodistribution and the incorporation of 111In-labelled F(ab')2 monoclonal antibody (MoAb) fragments directed against human PAP into human prostatic tumours (PC-82; 0.1-8.9 g) growing in nude mice. The radioactivities in the blood, liver, spleen, kidney and tumour were compared at 1, 3, 4 and 6 days after the intravenous administration of the antibody fragments. There was a significant correlation between the tumour size and the serum PAP concentration in the model employed. Even tissue of a small tumour (less than 0.1 g) had a high concentration of PAP, but it was not secreted into the circulation in detectable amounts when measured by radioimmunoassay (the lowest standard was 0.5 micrograms/l). The percentage uptake by tumours of the injected dose per gram of tissue (%ID/g) was inversely proportional to the tumour size at 24 h after the administration of 111In-labelled F(ab')2 fragments. This relationship had levelled off by 72 h and most likely reflected a better vascularisation of the smaller tumours. Our results show that the increase in tumour size and in the concentration of circulating antigen in the blood led to decreased tumour-to-blood ratios, since there was a tendency for higher blood activities in mice with larger tumours and higher serum PAP concentrations. There was no correlation between tumour size and label uptake by the liver during the follow-up over 144 h, although serum PAP concentrations ranged from 3.1 micrograms/l to 352 micrograms/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1991

Lack of association between prostate-specific acid phosphatase RFLP genotypes and prostatic cancer or benign prostatic hyperplasia.

We have previously reported the identification and basic characterization of two biallelic TaqI RFLPs, A and B, of the 3' end of the human ACPP locus in an unselected Finnish population (Winqvist et al., 1989). In the present investigation, a similar allelic distribution was observed in patients with prostatic cancer or benign hyperplasia. In addition, it was found that the DNA sequences generating RFLP-B are located further downstream from the RFLP-A sequences.

Acid Phosphatase↗
PubMed1990

Primary structure of rat secretory acid phosphatase and comparison to other acid phosphatases.

Overlapping cDNA clones encoding rat prostatic acid phosphatase (rPAP) were isolated by using two human prostatic acid phosphatase (hPAP)-encoding cDNAs to screen rat prostatic cDNA libraries. The isolated cDNAs encompassed a total of 1626 nucleotides (nt), of which 1143 nt corresponded to the protein coding sequence encoding a mature polypeptide of 350 amino acids (aa) and a 31-aa long signal peptide-like sequence. The deduced Mr of the mature rPAP was 40,599. RNA blot analysis indicated the presence of three mRNA species (4.9, 2.3 and 1.5 kb in size) in the rat prostate. The deduced aa sequences of rPAP and hPAP show 75% identity, whereas the similarity between rPAP and human lysosomal acid phosphatase (hLAP) is only 45%. Furthermore, the sequence similarity between rPAP and rat lysosomal acid phosphatase (rLAP) is 46% at the aa level. Similar to hPAP, but unlike hLAP and rLAP, the rPAP sequence lacks a membrane-anchoring domain indicating the secretory character of this phosphatase. All six cysteines present in the overlapping areas of the mature rPAP, hPAP, rLAP and hLAP proteins are positionally conserved, suggesting that these residues are important for the tertiary structure of acid phosphatases (APs). The previously reported active site residues, two arginines and one histidine, are also conserved in these APs.

Acid Phosphatase↗
PubMed1990

Expression of the gene coding for human prostate-specific antigen and related hGK-1 in benign and malignant tumors of the human prostate.

Human glandular kallikrein-1 gene (hGK-1) is closely related to the gene of human prostate-specific antigen (PSA) and both genes are expressed in the human prostate. We have studied PSA and hGK-1 mRNAs in human prostatic tissue samples from patients with benign prostatic hyperplasia (BPH) or adenocarcinoma (CA), using Northern and slot-blot analysis in order to gain insight into the expression of these highly similar genes. Multiple mRNAs were found to originate from both genes. The major mRNA species of 1.6 kb accounted for 57% to 76% of the total coding capacity for PSA in different tissue specimens, but a variant mRNA species of 1.9 kb was also abundant. Most of the BPH samples contained marked amounts of an aberrant 0.9 kb mRNA, and long PSA mRNAs of 6.1 kb, 4.5 kb and 3.1 kb were found in elevated amounts in some of the CA samples. The amount of PSA mRNAs that would produce aberrant PSA proteins if translated into protein varied from 18% to 38% in these tissue samples. The major mRNA species originating from hGK-1 was of 1.6 kb, but other less abundant mRNA species could also be observed. The amount of PSA and hGK-1 mRNAs was determined from slot blots hybridized with specific oligonucleotide probes. No significant differences could be found in the PSA gene expression between BPH and CA samples. The total amount of the PSA mRNAs in all the different BPH specimens was fairly similar, but there was a 3-fold difference between the highest and lowest PSA mRNA levels in the CA samples. The hGK-1 mRNA levels in the BPH specimens studied demonstrated greater variance than the PSA mRNA levels in the same samples. The correlation between PSA gene and hGK-1 expression in the BPH samples was good, suggesting that there are similarities in the regulation of these genes. However, the lack of correlation between the amounts of PSA and hGK-1 mRNAs in the CA samples except in sample C1 indicates that there are also differences in the gene regulation. The observed 3.7- to 6.5-fold excess of PSA mRNAs as compared with the amount of hGK-1 mRNAs present in the same tissue specimen also indicated differences in the cis- or trans-acting regulatory elements of these genes.

Antigens, Neoplasm↗
PubMed1990

Gene expression and prostate specificity of human prostatic acid phosphatase (PAP): evaluation by RNA blot analyses.

A fragment of a complementary DNA (cDNA) clone for human prostatic acid phosphatase (PAP) (EC 3.1.3.2.) was used to study the expression of corresponding mRNA in human tissues. The specificity of its expression in benign prostatic hyperplasia (BPH) and prostatic carcinoma tissues were indicated in RNA blot analyses. The PAPcDNA probe did not recognize any specific mRNAs in RNAs extracted from human liver cancer, lung cancer, pancreatic cancer, placenta, breast cancer cells (MCF-7), mononuclear blood cells or acute promyelocytic leukemia cells (HL-60), according to Northern blot analysis. mRNA for PAP was detected in the androgen-dependent human prostatic cancer cell line LNCaP, but not in the androgen-insensitive human prostatic cancer cell line PC-3. In contrast, lysosomal acid phosphatase (LAP) mRNA was detected in both of these human prostatic cancer cell lines. Our findings indicate a high specificity for the PAP gene in prostatic tissue. The mean abundance for the PAPmRNA expression was 0.26 for prostatic carcinoma samples (n = 11) and 0.46 for BPH samples (n = 8) according to slot-blot analysis. The differences observed between the different categories of prostatic tissue in PAPmRNA abundances call for additional studies on regulation of its expression.

Acid Phosphatase↗
PubMed1990

Biodistribution in normal mice of an 111In-labelled prostatic acid phosphatase-specific antibody and its F(ab')2 fragments derivatized site-specifically or via bicyclic diethylenetriaminepentaacetic acid anhydride.

In this study we examined optimization of derivatization of monoclonal antibodies and their fragments intended for use as radiopharmaceutical in radioimaging and/or radioimmunotherapy of prostatic cancer. Two different principles were used to conjugate diethylenetriaminepentaacetic acid (DTPA) to a monoclonal antibody (Mab, subclass IgG1) raised against human prostatic acid phosphatase (PAP). In addition, the F(ab')2 fragments of this Mab were also derivatized. We used the cyclic anhydride of DTPA (CA-DTPA) as a chelating agent for these two protein moieties. Furthermore, the Mab and the F(ab')2 fragments were modified site-specifically by attaching linkers, N-(p-aminobenzyl)diethylenetriaminetetraacetic acid (p-NH2-Bz-DTTA) and 1-(p-aminobenzyl)diethylenetriaminepentaacetic acid (p-NH2-Bz-DTPA), to the carbohydrate components of the parent molecules. In this study, biodistribution of the 111In-labelled derivatives was investigated in normal mice. All the derivatives of IgG1 demonstrated a slower blood clearance than the corresponding derivatives of the F(ab')2 fragments. This property was particularly pronounced in the site-specifically conjugated derivatives of IgG1. All the derivatives studied accumulated in the liver, kidney, and spleen. The CA-DTPA derivatives of F(ab')2 fragments showed the highest kidney-to-blood ratios of radioactivity compared with the other compounds studied. The derivatives of IgG1 showed a higher percentage of the injected dose in liver and spleen tissues than the derivatives of the F(ab')2 fragments. The F(ab')2 fragments studied also gave rise to site-specific derivatives, which demonstrated that carbohydrates were also present in this part of the molecule. They behaved similarly to the CA-DTPA F(ab')2 derivative in other respects, but the kidney accumulation was lower at 72 and 120 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1990

Time-resolved immunofluorometric assay of human prostate-specific antigen.

Assay of human serum prostate-specific antigen (PSA) is gaining importance in diagnosis and follow-up of prostatic cancer. In this time-resolved immunofluorometric assay of PSA, strip-wells were coated with a polyclonal antibody against PSA. To prepare the label, a monoclonal antibody displaying high affinity towards PSA was purified and derivatized with diethylenetriaminepentaacetic acid. With use of this derivative, seven to eight Eu atoms could be combined with one antibody molecule with no decrease in immunoreactivity. The minimum detectable concentration of PSA was 0.12 microgram/L. In 60 of 63 women studied, the PSA concentration in serum was less than 0.2 microgram/L. The increase in PSA in serum of asymptomatic men 51 years old or older, as compared with that for younger subjects, was possibly a result of "occult" prostatic hyperplasia. Most of the patients with prostatic hyperplasia or prostatic cancer had higher PSA concentrations than did subjects of ages less than 50 years or asymptomatic age-matched healthy subjects. Results compared favorably with those by an established technique relying on the use of radioactive label. Our method for measuring PSA in human serum is convenient, inexpensive, and well compatible with present clinical practice.

Aged↗
PubMed1989

cDNA coding for the entire human prostate specific antigen shows high homologies to the human tissue kallikrein genes.

We have isolated four cDNAs encoding the entire preproprotein of prostate specific antigen from human prostatic cDNA libraries. Comparison of the coding regions of prostate specific antigen with human pancreatic kallikrein (1-3) and human glandular kallikrein (4) showed 73%-84% nucleotide and 61-77% amino acid homologies, respectively, between these enzymes. Also the 3' noncoding regions of these genes were conserved. The close resemblance of prostate specific antigen, a marker for prostatic cancer, to glandular kallikrein suggests related immunogenic properties for them.

Amino Acid Sequence↗
PubMed1989

Purification of monoclonal antibodies raised against prostate-specific acid phosphatase for use in vivo in radioimaging of prostatic cancer.

In developing diagnostic reagents for the radioimaging of prostatic cancer, methods were optimized for the purification of two mouse IgG1 monoclonal antibodies raised against prostate-specific acid phosphatase and produced in cell culture. Two different two-step methods were selected. One method consisted of two successive ion exchange chromatographic steps on Mono S and Mono Q; in the other method, Mono S chromatography was followed by hydrophobic interaction (Alkyl Superose) chromatography. In both cases, fast protein liquid chromatography (FPLC) instrumentation was used. The antibodies were purified from cell culture media containing fetal calf serum (1-5%). Highly pure (greater than 95%) IgG1 antibodies, free of contaminating serum-derived proteins or column materials, were obtained in good yield (greater than 90% recovery). The purified antibodies completely retained their immunological reactivity towards prostate-specific acid phosphatase and were sterile and pyrogen-free. Since the monoclonal antibodies produced were intended for applications in vivo, an essential feature of the methods selected was the availability of in situ cleaning procedures for sterilization of the gel materials and for the inactivation of viruses and pyrogens in the gels. The methods developed could be readily scaled up for preparative purposes.

Acid Phosphatase↗
PubMed1989

Radiolabelling of monoclonal antibodies: optimization of conjugation of DTPA to F(ab')2-fragments and a novel measurement of the degree of conjugation using Eu(III)-labelling.

F(ab')2 fragments (at concentrations of 5-30 mg/ml) derived from monoclonal antibodies raised against human prostate specific acid phosphatase were derivatized with a bicyclic anhydride of diethylenetriaminepentaacetic acid (cDTPAA) in the molar ratios of cDTPAA/F(ab')2 of 1:1, 5:1, 10:1 or 50:1. The most optimal product, aimed at radioimaging of prostatic cancer was obtained when the antibody fragment concentration was at least 10 mg/ml and the molar ratio of cDTPAA to F(ab')2 was 5:1. cDTPAA was added dissolved in dimethylsulfoxide (DMSO). Under these conditions, 1.8-2.2 DTPA molecules/F(ab')2 molecule were bound, giving a coupling efficiency of 37%-44%, and the labelling efficiency with 111In (3 mCi/1 mg protein) was 95% +/- 3% (n = 7). The antibody fragment completely retained its immunoreactivity measured by radioimmunoassay and showed no aggregation when studied using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE). For evaluation of the degree of conjugation of DTPA to the antibody fragment, a novel technique was developed relying on the use of EuCl3, and the measurement of europium fluorescence employing time resolved fluorometry. Results by EuCl3 labelling were identical to those obtained by the conventional 111InCl3 labelling method.

Acid Phosphatase↗
PubMed1989

Chromosomal localization to 3q21----qter and two TaqI RFLPs of the human prostate-specific acid phosphatase gene (ACPP).

The chromosomal location of the gene encoding human prostate-specific acid phosphatase (ACPP) was determined by Southern blotting analysis of panels of human x rodent (mouse or Chinese hamster) somatic cell hybrids, using the PAP-1007 and PAP-1004EP ACPP cDNA probes. The ACPP gene was assigned to chromosome 3, which was confirmed by screening a chromosome 3-specific genomic library. Sublocalization of this gene was carried out using hybrids that had retained only various portions of human chromosome 3. The ACPP gene was found to segregate specifically with the chromosomal segment 3q21----qter. Analysis of Southern blots of TaqI-digested DNAs from unrelated individuals and members of large families from northern Finland revealed two simultaneous diallelic restriction fragment length polymorphisms (RFLPs), A and B, when using either PAP-1004EP or PAP-1006A ACPP cDNA probes, but not the 5' flanking PAP-1007 probe. Allele frequencies for polymorphism A were .09 (A1) and .91 (A2), and for polymorphism B, .38 (B1) and .62 (B2). There appears to be only a very minor linkage disequilibrium (chi 2 = 1.12, 0.35 greater than P greater than 0.25) between the two TaqI RFLPs at the ACPP locus. For reasons presently unknown, homozygotes for polymorphism B appear to be overrepresented. These polymorphisms could be of importance in characterizing human prostate cancer.

Acid Phosphatase↗
PubMed1989

High degree of homology between primary structure of human lysosomal acid phosphatase and human prostatic acid phosphatase.

Alignment of the amino-acid sequences of the human lysosomal acid phosphatase (LAP) and human prostatic acid phosphatase (PAP) yielded an extensive homology between the two mature polypeptide chains. In the overlapping part, which extends over the entire PAP sequence and the N-terminal 90% of the LAP sequence, the identity is 49.1%. The LAP has an additional C-terminal sequence, which is encoded by the last exon of the LAP gene. This sequence contains the transmembrane domain of LAP, which is lacking in the secretory PAP. All six cysteine residues as well as 20 out of 27 (LAP) and 26 (PAP) proline residues present in the overlapping part of the proteins are conserved, suggesting that they are involved in stabilization of the tertiary structure of both proteins. Only two out of 8 N-glycosylation sites in LAP and 3 in PAP are conserved, suggesting that the dense N-glycosylation of LAP is related to its function in lysosomes.

Acid Phosphatase↗
PubMed1988

Molecular cloning and sequence analysis of cDNA encoding human prostatic acid phosphatase.

lambda gt11 clones encoding human prostatic acid phosphatase (PAP) (EC 3.1.3.2) were isolated from human prostatic cDNA libraries by immunoscreening with polyclonal antisera. Sequence data obtained from several overlapping clones indicated that the composite cDNAs contained the complete coding region for PAP, which encodes a 354-residue protein with a calculated molecular mass of 41,126 Da. In the 5'-end, the cDNA codes for a signal peptide of 32 amino acids. Direct protein sequencing of the amino-terminus of the mature protein and its proteolytic fragments confirmed the identity of the predicted protein sequence. PAP has no apparent sequence homology to other known proteins. However, both the cDNA clones coding for human placental alkaline phosphatase and PAP have an alu-type repetitive sequence about 900 nucleotides downstream from the coding region in the 3'-untranslated region. Two of our cDNA clones differed from others at the 5'-ends. RNA blot analysis indicated mRNA of 3.3 kb. We are continuing to study whether acid phosphatases form a gene family as do alkaline phosphatases.

Acid Phosphatase↗
PubMed1988

Preparation of F(ab')2 fragments from monoclonal mouse IgG1 suitable for use in radioimaging.

Monoclonal antibodies of IgG1 subclass raised against purified human prostate-specific acid phosphatase were subjected to different procedures to produce F(ab')2 fragments suitable for radioimaging of prostatic cancer, following derivatization and labeling with radionuclides. The main aim was to obtain highly purified fragments with preserved immunological activity. Optimized pepsin digestion led to the formation of mainly F(ab')2 and Fab fragments, and, following Sephacryl S-200 gel filtration, the yield of pure F(ab')2 fragments was 24 +/- 11% of the theoretical maximum. After papain digestion in the absence of thiols, no formation of Fab fragments was observed, and the F(ab')2 fragments formed could be efficiently separated from Fc fragments by chromatofocusing or ion exchange chromatography. The yield of F(ab')2 fragments from papain digestion was 50 +/- 5% of the theoretical maximum. Both the above procedures gave F(ab')2 fragments with immunoreactivity and affinity identical to those of the precursor IgG1, despite the fact that isoelectric focusing profiles of the two F(ab')2 preparations differed, suggesting different digestion sites.

Acid Phosphatase↗