Tetranectin in cerebrospinal fluid of patients with multiple sclerosis

OBJECTIVE

Tetranectin (TN) is a glycoprotein and C-type lectin thought to play a prominent role in tissue remodelling. The aim of this study was to determine the TN serum and cerebrospinal fluid (CSF) concentration in patients with multiple sclerosis (MS) and controls.

MATERIAL AND METHODS

Two-hundred-and-four patients, divided into four diagnostic groups, i.e. definite MS (n = 76), possible onset symptoms of MS (n = 48), other non-inflammatory neurological diseases (n = 61) and other inflammatory neurological diseases (n = 19) and 47 controls with no history of neurological disease were analysed for TN in serum and CSF using a polyclonal sandwich ELISA.

RESULTS

All tested groups, e.g. definite MS, possible onset symptoms of MS, other neurological disease, both inflammatory and non-inflammatory, had decreased concentrations of TN in the CSF compared to the concentrations in controls. The quotient of TN in CSF divided by the concentration in serum (QTN) correlated significantly with the same quotient of albumin (QALB), was significantly correlated with the same quotient of albumin QALB. To account for differences in blood brain barrier permeability, we calculated a TN-index defined as: TN-index = QTN/QALB. QTN was significantly decreased in all groups compared to that in controls. However, in definite MS and patients with first attack of MS, the TN-index was not significantly different from that of controls. In contrast, other neurological diseases, both inflammatory and non-inflammatory, were associated with a decreased TN-index.

CONCLUSION

These results indicate that TN may play a role in neurological diseases and may serve as a diagnostic aid in MS.

Evaluation of the topoisomerase II-inactive bisdioxopiperazine ICRF-161 as a protectant against doxorubicin-induced cardiomyopathy

Anthracycline-induced cardiomyopathy is a major problem in anti-cancer therapy. The only approved agent for alleviating this serious dose limiting side effect is ICRF-187 (dexrazoxane). The current thinking is that the ring-opened hydrolysis product of this agent, ADR-925, which is formed inside cardiomyocytes, removes iron from its complexes with anthracyclines, hereby reducing the concentration of highly toxic iron-anthracycline complexes that damage cardiomyocytes by semiquinone redox recycling and the production of free radicals. However, the 2 carbon linker ICRF-187 is also is a catalytic inhibitor of topoisomerase II, resulting in the risk of additional myelosuppression in patients receiving ICRF-187 as a cardioprotectant in combination with doxorubicin. The development of a topoisomerase II-inactive iron chelating compound thus appeared attractive. In the present paper we evaluate the topoisomerase II-inactive 3 carbon linker bisdioxopiperazine analog ICRF-161 as a cardioprotectant. We demonstrate that this compound does chelate iron and protects against doxorubicin-induced LDH release from primary rat cardiomyocytes in vitro, similarly to ICRF-187. The compound does not target topoisomerase II in vitro or in cells, it is well tolerated and shows similar exposure to ICRF-187 in rodents, and it does not induce myelosuppression when given at high doses to mice as opposed to ICRF-187. However, when tested in a model of chronic anthracycline-induced cardiomyopathy in spontaneously hypertensive rats, ICRF-161 was not capable of protecting against the cardiotoxic effects of doxorubicin. Modulation of the activity of the beta isoform of the topoisomerase II enzyme by ICRF-187 has recently been proposed as the mechanism behind its cardioprotection. This concept is thus supported by the present study in that iron chelation alone does not appear to be sufficient for protection against anthracycline-induced cardiomyopathy.

A mouse model for studying the interaction of bisdioxopiperazines with topoisomerase IIalpha in vivo

The bisdioxopiperazines such as (+)-(S)-4,4'-propylenedi-2,6-piperazinedione (dexrazoxane; ICRF-187), 1,2-bis(3,5-dioxopiperazin-1-yl)ethane (ICRF-154), and 4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione (ICRF-193) are agents that inhibit eukaryotic topoisomerase II, whereas their ring-opened hydrolysis products are strong iron chelator. The clinically approved analog ICRF-187 is a pharmacological modulator of topoisomerase II poisons such as etoposide in preclinical animal models. ICRF-187 is also used to protect against anthracycline-induced cardiomyopathy and has recently been approved as an antidote for alleviating tissue damage and necrosis after accidental anthracycline extravasation. This dual modality of bisdioxopiperazines, including ICRF-187, raises the question of whether their pharmacological in vivo effects are mediated through interaction with topoisomerase II or via their intracellular iron chelating activity. In an attempt to distinguish between these possibilities, we here present a transgenic mouse model aimed at identifying the contribution of topoisomerase IIalpha to the effects of bisdioxopiperazines. A tyrosine 165 to serine mutation (Y165S) in topoisomerase IIalpha, demonstrated previously to render the human ortholog of this enzyme highly resistant toward bisdioxopiperazines, was introduced at the TOP2A locus in mouse embryonic stem cells by targeted homologous recombination. These cells were used for the generation of transgenic TOP2A(Y165S/+) mice, which were demonstrated to be resistant toward the general toxicity of both ICRF-187 and ICRF-193. Hematological measurements indicate that this is most likely caused by a decreased ability of these agents to induce myelosuppression in TOP2A(Y165S/+) mice, highlighting the role of topoisomerase IIalpha in this process. The biological and pharmacological implications of these findings are discussed, and areas for further investigations are proposed.

Combining Etoposide and Dexrazoxane Synergizes with Radiotherapy and Improves Survival in Mice with Central Nervous System Tumors

PURPOSE

The treatment of patients with brain metastases is presently ineffective, but cerebral chemoradiotherapy using radiosensitizing agents seems promising. Etoposide targets topoisomerase II, resulting in lethal DNA breaks; such lesions may increase the effect of irradiation, which also depends on DNA damage. Coadministration of the topoisomerase II catalytic inhibitor dexrazoxane in mice allows for more than 3-fold higher dosing of etoposide. We hypothesized that dexrazoxane combined with escalated etoposide doses might improve the efficacy of cerebral radiotherapy.

EXPERIMENTAL DESIGN

Mice with cerebrally inoculated Ehrlich ascites tumor (EHR2) cells were treated with combinations of etoposide + dexrazoxane + cerebral radiotherapy. Similar chemotherapy and radiation combinations were investigated by clonogenic assays using EHR2 cells, and by DNA double-strand break assay through quantification of phosphorylated histone H2AX (gammaH2AX).

RESULTS

Escalated etoposide dosing (90 mg/kg) combined with dexrazoxane (125 mg/kg) and cerebral radiotherapy (10 Gy x 1) increased the median survival by 60% (P = 0.001) without increased toxicity, suggesting that escalated etoposide levels may indeed represent a new strategy for improving radiotherapy. Interestingly, 125 mg/kg dexrazoxane combined with normal etoposide doses (34 mg/kg) also increased survival from radiotherapy, but only by 27% (P = 0.002). This indicates a direct dexrazoxane modulation of the combined effects of etoposide and radiation in brain tumors. Further, in vitro, concurrent dexrazoxane, etoposide, and irradiation significantly increased DNA double-strand breaks.

CONCLUSION

Combining etoposide (high or normal doses) and dexrazoxane synergizes with cerebral radiotherapy and significantly improves survival in mice with central nervous system tumors. This regimen may thus improve radiation therapy of central nervous system tumors.

Dexrazoxane Protects against Myelosuppression from the DNA Cleavage–Enhancing Drugs Etoposide and Daunorubicin but not Doxorubicin

PURPOSE

The anthracyclines daunorubicin and doxorubicin and the epipodophyllotoxin etoposide are potent DNA cleavage-enhancing drugs that are widely used in clinical oncology; however, myelosuppression and cardiac toxicity limit their use. Dexrazoxane (ICRF-187) is recommended for protection against anthracycline-induced cardiotoxicity.

EXPERIMENTAL DESIGN

Because of their widespread use, the hematologic toxicity following coadministration of dexrazoxane and these three structurally different DNA cleavage enhancers was investigated: Sensitivity of human and murine blood progenitor cells to etoposide, daunorubicin, and doxorubicin +/- dexrazoxane was determined in granulocyte-macrophage colony forming assays. Likewise, in vivo, B6D2F1 mice were treated with etoposide, daunorubicin, and doxorubicin, with or without dexrazoxane over a wide range of doses: posttreatment, a full hematologic evaluation was done.

RESULTS

Nontoxic doses of dexrazoxane reduced myelosuppression and weight loss from daunorubicin and etoposide in mice and antagonized their antiproliferative effects in the colony assay; however, dexrazoxane neither reduced myelosuppression, weight loss, nor the in vitro cytotoxicity from doxorubicin.

CONCLUSION

Although our findings support the observation that dexrazoxane reduces neither hematologic activity nor antitumor activity from doxorubicin clinically, the potent antagonism of daunorubicin activity raises concern; a possible interference with anticancer efficacy certainly would call for renewed attention. Our data also suggest that significant etoposide dose escalation is perhaps possible by the use of dexrazoxane. Clinical trials in patients with brain metastases combining dexrazoxane and high doses of etoposide is ongoing with the aim of improving efficacy without aggravating hematologic toxicity. If successful, this represents an exciting mechanism for pharmacologic regulation of side effects from cytotoxic chemotherapy.

Tetranectin-like protein in vertebrate serum: a comparative immunochemical analysis

The glycoprotein tetranectin (TN) found in human serum is a 90-kDa homotrimeric C-type lectin binding Ca2+, heparin and plasminogen kringle 4. TN is suggested as being implicated in tissue remodelling. The antigenic reactivity of putative TN was examined in serum from 14 different animal species using three sandwich enzyme immunoassays for human TN. Crab-eating macaque serum showed the strongest reaction, followed by horse and cat. Serum from cow, goat, pig, mouse and chicken reacted weakly, while dog, trout, and the amphibian and the reptile species did not react. The TN-like protein from macaque, horse and cat serum bound heparin and showed the same dependence on Ca2+ for interaction with the monoclonal antibodies as human TN. Gel filtration of sera from the three animal species showed that the TN-like protein eluted as single peaks with a M(r) of 70-90 kDa. Western blotting of horse and cat TN-like protein electrophoresed under reducing conditions showed that the antibodies against human TN reacted with a single band with an approximate M(r) of 30 kDa, indicating that the TN-like protein is also a homotrimer. Horse and cat TN-like protein interacted with human kringle 4-sepharose. Most likely, the reacting protein represents crab-eating macaque, horse and cat homologues of human TN.

Correlation between alpha 1-acid glycoprotein and total sialic acid in serum from dogs with tumours

The influence of the acute phase protein alpha 1-acid glycoprotein (AGP) on the concentration of total sialic acid (TSA) in serum was investigated by assessing their degree of correlation in 115 clinically healthy dogs, 29 dogs with malignant mammary tumours, 12 dogs with various other malignant tumours, 12 dogs with benign mammary tumours and 10 dogs with various other benign tumours. Serum from dogs with malignant mammary tumours and other malignant tumours had a statistically significant correlation between AGP and TSA concentrations (Spearman correlation coefficient (rS) = 0.52, P = 0.0005, n = 41). The correlation was also statistically significant in dogs with benign mammary tumours and other benign tumours (rS = 0.48, P = 0.02, n = 22). The Spearman correlation coefficient was 0.51 (P = 0.0001, n = 63) in all dogs with tumours. This was also the case if only those dogs with levels of AGP comparable to healthy dogs (< 750 mg/l) were included in the analysis (rS = 0.42, P = 0.01, n = 56). In clinically healthy dogs, the correlation was not statistically significant (rS = 0.17, P = 0.07, n = 115). None of the four groups of dogs with tumours had changed serum AGP concentrations compared to clinically healthy dogs (all t-tests gave P values above 0.05). The serum concentrations of AGP did not correlate with the clinical stage of dogs with mammary tumours. In conclusion, AGP and TSA concentrations in serum are positively correlated in dogs with tumours, partially explaining the increase in serum TSA in these dogs. Increased sialylation of the AGP molecule in dogs with tumours might contribute to the increased serum TSA levels.

Total serum sialic acid is a general disease marker rather than a specific tumour marker in dogs

The aim of the present study was to examine the levels of total sialic acid (TSA) in serum of clinically healthy dogs and dogs with various diseases to evaluate the usefulness of TSA as a tumour marker. TSA levels in clinically healthy dogs were not different between sexes, but pregnant and lactating dogs had higher mean (+/- standard deviation (SD)) TSA levels than clinically healthy female dogs (642 +/- 78 vs. 495 +/- 73 mg/l, P < 0.001). Eighty-eight dogs with different tumours (54 malignant and 34 benign tumours of different tissues) had higher mean TSA levels than 148 clinically healthy dogs (675 +/- 143 vs. 498 +/- 75 mg/l, P < 0.01). Fifty dogs with other diseases excluding tumours (skin, urinary system, and gastrointestinal diseases, pyometra, other inflammatory diseases, and Cushing's syndrome) had slightly higher TSA levels than the tumour-bearing dogs (730 +/- 159 mg/l, P = 0.02). TSA levels in dogs with malignant tumours did not differ from dogs with benign tumours (682 +/- 144 vs. 664 +/- 142 mg/l, P = 0.73). A receiver-operating characteristic (ROC) plot revealed a maximum sensitivity and specificity combination of 69% and 91% (TSA cut-off concentration 595 mg/l) in distinguishing between healthy dogs and dogs with tumours. When evaluating TSA measurements to distinguish dogs with other diseases from dogs with tumours, a maximum sensitivity and specificity combination of 50% and 75% was found (cut-off concentration 761 mg/l). WHO staging of mammary tumours revealed an increase in TSA levels with increasing stage (P < 0.0001, rs, = 0.62). In conclusion, the nonspecificity of increases makes TSA determinations unsuitable as a tumour marker. TSA levels seem instead to be a general disease marker. Whether serial TSA measurements could be used in the follow-up of dogs operated for malignant tumours should be further investigated.

Determination of serum tetranectin: technical and clinical evaluation of three sandwich immunoassays

The performance of two sandwich-type immunoassays for the determination of the tumour marker tetranectin using monoclonal antibodies Hyb 130-13 and 130-14 as catching layer was compared with the performance of a polyclonal assay. Sensitivities were 0.4-0.6 microg/l, and intra- and inter-assay coefficients of variation were < 10% in all assays. One-hundred-and-ten blood donors were examined, and women had higher concentrations of tetranectin in serum than men when measured with monoclonal assays (P < 0.05). In preoperative serum samples from 43 patients with ovarian cancer, tetranectin concentrations were reduced (P < 0.001), and the mean tetranectin concentration decreased with increasing FIGO stage of the patients (P < 0.05). In sera from patients with ovarian cancer, tetranectin concentrations were lower in the polyclonal assay than in the monoclonal assays. This could, hypothetically, be explained by ligand-binding or other conformational changes in tetranectin, influencing the antigenicity of the molecule.

Evaluation of an automated spectrophotometric assay for the determination of total sialic acid in canine serum

This study validates an automated enzymatic assay using the Cobas Fara (Roche) centrifugal analyser, which offers a reliable measurement of the total sialic acid concentration in canine serum as assessed by evaluating the precision and accuracy. Data are presented on the biological variation in the total serum sialic acid concentration. Measurements of total serum sialic acid concentration appear to be useful in distinguishing dogs with neoplastic disorders from clinically healthy dogs.