Expression of human placental-type alkaline phosphatase in primary breast cancer

A monoclonal antibody (H317) with specificity for the heat-stable placental-type alkaline phosphatase (PI-ALP) isoenzyme has been used to investigate the occurrence of PI-ALP in patients with primary breast carcinoma. All pre-operative plasma samples were negative for PI-ALP in a sensitive solid-phase enzyme immunoassay with a lower limit of detection of 0.1 U/l. In contrast, using a peroxidase-anti-peroxidase staining technique on fixed tissue sections, as well as enzyme immunoassay on fresh tissue extracts, PI-ALP could be demonstrated in the carcinomatous tissue of all seven patients investigated.     

Expression of placental alkaline phosphatase in epithelial ovarian tumours

The expression of placental alkaline phosphatase in 116 ovarian epithelial tumours was examined in formalin-fixed tissues used for routine histopathologic examination. In the total material, 51% of the tumours displayed positive immunoreactivity, as described by the monoclonal anti-placental alkaline phosphatase antibody C2, with similar incidence (46-67%) in the four major groups of the adenocarcinomas, i.e., serous, mucinous, endometrioid and mesonephric tumours. By use of a histochemical staining index the mucinous and mesonephric tumours demonstrated a more intense staining (2.1 and 2.6) compared to the serous and endometrioid tumours (0.9 and 1.5). The relevance of the findings is discussed in relation to the use of monoclonal antibody technologies for radioimmunolocalization and radioimmunotherapy.     

Levels of alkaline phosphatase isozymes in human seminoma tissue

The three human isozymes of alkaline phosphatases were quantitatively determined in normal testis and seminoma tissues. The highly selective assays were based on isozyme specific monoclonal antibodies. In the normal testis approximately 90% of the catalytic activity originates from the tissue unspecific alkaline phosphatase, and the remaining activity was due to trace expression of both intestinal (approximately 5%) and placental alkaline phosphatase (PLAP) or PLAP-like isozyme (approximately 5%). In homogenates of seminoma tissues, highly increased levels of all three isozymes were identified. Both the tissue unspecific alkaline phosphatase and PLAP-like enzymes displayed relative increases of 10- to 100-fold and intestinal alkaline phosphatase 2- to 10-fold compared with normal testis. This finding indicates that the entire genome coding for alkaline phosphatases may be activated in seminomas. The PLAP-like enzyme from seminoma cells comprises a heterogenous population of molecules demonstrating partial heat sensitivity and microheterogeneity upon starch gel electrophoresis in contrast to the pregnancy related PLAP. These findings have implications for the different PLAP assays used in the clinical monitoring of seminoma patients.     

Demonstration of placental alkaline phosphatase in human breast cancer.

The screening of a series of 11 metastatic breast tumors for the presence of the placental isoenzyme of alkaline phosphatase (EC3.1.3.1) by RIA revealed one strong producer. The alkaline phosphatase of this tumor was characterized with respect to its immunochemical cross-reactivity, inhibition by L-phenylalanine and levamisole, subunit molecular weight (Mr) and isoelectric point (pl) in two-dimensional electrophoresis, and one-dimensional peptide map. In all parameters of the characterization, the tumor alkaline phosphatase, except for subunit molecular weight which was slightly lower (60,000 versus 64,000 for the placental isoenzyme). No strong placental alkaline phosphatase producers were found among 16 primary tumors examined by RIA. The screening of patients' sera for the placental alkaline phosphatase using RIA indicated elevated levels over post-menopausal controls in 20% of the metastatic patients. Only 3% of the primary patients had elevated serum levels. These results suggest that the placental isoenzyme of alkaline phosphatase may be a useful tumor marker for recurrent breast cancer.     

Presence of the rare D-variant heat-stable, placental-type alkaline phosphatase in normal human testis

In 11 adult testes studied, about 0.3 to 4.6% of the total alkaline phosphatase activity was heat stable and L-phenylalanine sensitive but L-homoarginine insensitive. The testicular heat-stable enzyme was more susceptible to inhibition by L-leucine and ethylenediaminetetraacetate than were the normal placental and intestinal enzymes. By antibody-directed enzyme inhibition test, the testicular heat-stable enzyme cross-reacted completely with normal placental enzyme but clearly distinguished itself from a heat-stable component of normal intestinal enzyme. Thus, placental alkaline phosphatase D-variant is synthesized in testis, indicating that the gene for elaborating this placental protein is probably already active in the testicular cells. The high incidence of this protein in cancers of testis and ovary is probably due to its increased production by gonadal genes present in the genome of these particular tumors.     

Serum alpha-fetoprotein and variant alkaline phosphatase in human hepatocellular carcinoma

Alpha-fetoprotein and variant alkaline phosphatase were studied in a group of patients with hepatoma. The incidence of positive alpha-fetoprotein was 67.6% in confirmed cases. Variant alkaline phosphatase was present only in patients with positive fetoprotein test, and it appeared in only 28.6% of the cases.     

EXPRESSION OF PLACENTAL ALKALINE PHOSPHATASE IN ESOPHAGEAL CANCER CELL LINE Eca109

Placentalalkalinephosph'atase(PLAP)hasbeenshowntobeaoncodevelopmentalgeneproduct,whichismostfrequefltlyproducedbysomehumanmalignanttumorsandtumor-derivedcelllines,suchasovariancancer.cervicalcancerandtesticularcancer."2IthasheretoforenotbeendeportedthatesophagealcancerorcelllineeXPresstheenzyme.Forthisreason,westudieditsexpressionandprednisoloneinductioninesophagealcancercellline,Ecal09.MATERIALSANDMETHODSCellCultureandPrednisoloneTreatmentEca109cellowereobtainedfromDepartmentofCe…     

Identification and characterization of alkaline phosphatase isozymes in human colorectal adenocarcinomas

Using alkaline phosphatase isozyme-specific immunocatalytical assays, the content of isozymes was determined in normal mucosas and adenocarcinomas from human colon or rectum. Tumor levels of both the tissue (liver)-unspecific and the placental-like alkaline phosphatase (PLAP-like) were elevated compared to normal mucosas of the same patients. Such elevations have been reported previously, particularly in seminomas and ovarian tumors. In several tumors, moreover, the intestinal isozyme was expressed in lesser amounts than in the adjacent mucosa. The present results indicate that the activation of two of the phosphatase isozymes, including expression of the typical germ cell line phosphatase (the PLAP-like isozyme), may occur even in nongonadal tumors. This may reflect an induction pattern of phosphatase isozymes, with implications for malignant transformation also in other tumors.     

Monoclonal antibodies to an ectopically expressed alkaline phosphatase in a human malignant cell line

The D98/AH-2 cell line (a subline of HeLa) expresses a form of alkaline phosphatase (ALP) which closely resembles the adult and fetal intestinal forms of ALP. To characterize this ectopic form of ALP, four monoclonal antibodies were raised against D98/AH-2 ALP, and their binding with ALPs from D98/AH-2 cells, placenta, fetal intestine (meconium), adult intestine, and liver was compared using an electrophoretic titration procedure. The ALPs were either untreated or treated with neuraminidase. All four monoclonal antibodies bound desialated D98/AH-2 ALP most strongly. Adult intestinal ALP, which does not contain sialic acid residues, reacted much more strongly than either sialated or desialated fetal intestinal ALP. Two of the four monoclonal antibodies reacted very weakly or not at all with placental ALP, but two others reacted more strongly with placental ALP than with fetal intestinal ALP. None of the antibodies reacted with liver ALP. From these results, it appears that D98/AH-2 ALP may be a modified form of adult intestinal ALP.     

A hidden antigenic determinant on membrane-bound human placental alkaline phosphatase

Two sets of monoclonal antibodies (mAbs) specific for human placental alkaline phosphatase (PLAP) were compared. One set of four mAbs was generated against solubilized and purified PLAP; the other set of seven mAbs was generated against the malignant cell line Hela TCRC-1 in which PLAP is an ectopically synthesized membrane-bound enzyme. Double immunodiffusion and competitive enzyme-linked immunosorbent assays were used to examine the relative spatial arrangement of the antigenic determinants to which each of the eleven mAbs binds. Significant differences in immunoreactivity of the antibodies were demonstrated. The mAbs to the solubilized and purified enzyme bound in either of two regions of the molecule. By contrast, all of the mAbs to PLAP as presented on the tumor cell surface bound in only one of these two regions. One of the major antigenic determinants on the solubilized enzyme is apparently unavailable for recognition by immunoreactive cells during immunization with whole cells. Furthermore, when mAbs are generated to this region using purified PLAP as the immunogen, they do not recognize membrane-bound PLAP. The 'hidden' determinant can be exposed in vitro after partial solubilization using butanol to extract the enzyme from HeLa TCRC-1 cells and subsequent treatment with 0.5% Nonidet P-40 detergent. The results of this study have implications for the potential use of mAbs in studies of other cell surface antigens and in tumor immunolocalization and drug targeting.     

Expression of prostatic acid phosphatase in human prostate cancer

By a specific immunochemical measurement, the activity of prostatic acid phosphatase (PAP) in prostate cancer was found to be about 25%, on average, based on μg DNA or per cell, of that in normal prostate or benign prostatic hypertrophy (BPH). The reduction of PAP in prostate cancer was further revealed by a decrease in PAP protein. The ¹²⁵I-labeled anti-PAP IgG specifically bound to nascent peptides on PAP-synthesizing polysomes showed no qualitative differences among cancerous prostate, normal prostate and BPH. However, the quantitative binding of ¹²⁵I-labeled anti-PAP IgG to polysomes of cancerous prostate was half that of normal prostate or BPH. These data suggest that a significant amount of PAP and its synthesizing polysomes was reduced in prostate cancer as a result of PAP gene suppression.     

Expression of KB cell alkaline phosphatase isoenzymes during growth in immunosuppressed LEW rats.

Alkaline phosphatase isoenzyme expression of human tumor xenografts was studied by the growing of KB cells in immunosuppressed neonatal LEW rats. In culture these cells produced the oncoamniotic (FL) isoenzyme as the major form and the Regan isoenzyme as a minor fraction as well as a "hybrid" that shared properties of both of the other isoenzymes. Despite a reduction in specific activity, this isoenzyme pattern was essentially unchanged during in vivo growth. KB cells "pretreated" in culture with the glucocorticoid prednisolone in hyperosmolal medium exhibited a decrease in the levels of the oncoamniotic (FL) isoenzyme and an increase in the Regan isoenzyme. During growth of pretreated cells in vivo, a time-dependent resumption in the expression of the oncoamniotic (FL) isoenzyme was associated with the disappearance of the Regan isoenzyme. This shows that the expression of the oncoamniotic (FL) isoenzyme is not restricted to human tumor cells monophenotypic with respect to alkaline phosphatase.     

Expression on cultured human tumour cells of placental trophoblast membrane antigens and placental alkaline phosphatase defined by monoclonal antibodies

The cellular reactivity of six monoclonal antibodies (McAbs) produced to isolated human placental syncytiotrophoblast microvillous plasma membranes has been examined using a variety of normal and malignant cell types. Two McAbs reacted with antigenic determinants common to most normal human cells. Two other McAbs (H310 and H316) reacted predominantly with normal placental trophoblast and with lymphocytic cells, as well as with most transformed or neoplastic cultured cell lines. Two further McAbs (H315 and H317) identified foetal differentiation antigens expressed only on the membranes of normal placental trophoblast and of certain tumor cell lines. H317 has been shown to be specific for the heatstable L-phenylalanine-inhibitable placental-type alkaline phosphatase isoenzyme. These latter McAbs (H315 and H317) may prove useful in monitoring of some human cancers.