Nucleases and adenosine 3',5'-cyclic monophosphate phosphodiesterase activities in murine sarcoma virus (Moloney)-infected mice.

To provide information on the role of nucleases in oncogenic virus infection, the activities of 3'-nucleotide phosphodiesterase (3'-NPDase), 5'-nucleotide phosphodiesterase (5'-NPDase), acid deoxyribonuclease (DNase II), and 3',5'-cyclic AMP phosphodiesterase (cAMPDase) in spleen extracts of murine sarcoma virus-infected C57BL/6 inbred mice were studied. At the peak of tumor growth and of the cell-mediated cytotoxic response (CMC) against tumor-associated antigens, 3'-NPDase, 5'-NPDase, and DNase II all showed depressed activities in the spleen, whereas the activity of cAMPDase in the spleen increased at the peak of CMC and remained elevated thereafter. Serum enzyme activities of the infected mice were also determined, and only 3'-NPD-ase in serum correlated well with CMC. Inasmuch as the correlation of the tumor growth with CMC was established in this system, further study on tumors with variance between CMC and growth is necessary to determine if serum 3'-NPDase is a useful biochemical marker for CMC in vivo.

Effect of deoxyribonuclease on adriamycin-polynucleotide complexes.

Recent interest in the use of adriamycin-DNA complex as an approach to improve the therapeutic effectiveness and to reduce toxicity of adriamycin for cancer chemotherapy requires an in-depth understanding of the physicochemical and biochemical properties of such complexes. The interactions of adriamycin with single-strand polydeoxyribonucleotides, double-strand DNA, and double-strand ribodeoxyribopolynucleotide hybrids were therfore investigated. Association constants (Kapp) of adriamycin and polynucleotides were obtained. These data showed that the inherent variable in such complex lies in the composition of the polynucleotides. Alternate deoxyguanylate (dG)-deoxycytidylate (dC) sequence binds 7-fold better than alternate deoxyadenylate (dA)-deoxythymidylate (dT) sequence. Comparative studies of the hydrolysis of DNA duplexes by deoxyribonucleases I and II with and without adriamycin were also carried out. The rate of hydrolysis decreased in the order poly(dA-dT) greater than calf thymus DNA greater than poly(dG-dC) greater than poly(dA)-poly(dT) greater than poly(dG)-poly(dC) for DNase I and poly(dA)-dT) greater than calf thymus DNA greater than poly(dG-dC) greater than poly(dA)-poly(dT) greater than poly(dG)-poly(dC) for DNase II. Intercalation of adriamycin to deoxyribopolynucleotide duplex resulted in inhibition of DNase II two to three times more than tat of DNase I. On the other hand, intercalation of adriamycin to homodeoxypolynucleotide duplex poly(dA)-poly(dT) and poly(dG)-poly(dC) enhanced the DNase I hydrolysis. If DNase I activity could be related to serum DNase and DNase II related to tumor lyososomal DNase as in the endocytosis mechanism proposed by Trouet et al. (Cancer Chemotherapy Rept., 59: 260, 1975), the best adriamycin carrier suggested by this investigation could be poly(dA)-poly(dT) and poly(dG-dC). It is also suggested in this study that adriamycin-RNA-DNA hybrid could be of interest as an antiviral agent by a similar release mechanism via RNase H, an enzyme associated with viral reverse transcriptase.

Rational selection of adjuvant chemotherapy after cytoreduction surgery for murine neuroblastoma.

Improving the prognosis of advanced neuroblastoma remains an important yet unachieved goal of pediatric oncology, a fact which may be related to an insufficient analysis of the role played by cytoreductive surgery. Utilizing strain A mice bearing C-1300 syngeneic neuroblastoma, tumor biology and host immunocompetence were studied after cytoreduction surgery and adjuvant chemotherapy. Cell kinetic analysis in the residual tumor demonstrated an increase of the proliferative fraction 18 to 42 h after operation, but the same peak proliferation was delayed in bone marrow cells to 24 to 96 h. The potential for drug distribution to the tumor after cytoreduction surgery was assessed by injecting Na251CrO4 and measuring tumor uptake. There were two significant (P less than 0.05) peaks of activity at 6 h and 3 days, suggesting local edema and neovascularity, respectively. Injection of both cell cycle specific and nonspecific adjuvant chemotherapeutic agents in a dosage of one-fourth of their 50% lethal dose at 24 or 72 h following surgical cytoreduction did not induce any antitumor activity at either injection time. However, when cyclophosphamide was given in this dose, the C-1300 tumor growth was impaired, an effect which was largely abrogated by first subjecting the tumor bearer to thymectomy and irradiation. The transfer of spleen cells from adjuvant cyclophosphamide-treated mice to tumor-inoculated normal mice significantly delayed tumor appearance when comparison was made with animals treated by operation alone, and such recipients also exhibited a more prolonged survival. These data suggest that the antitumor activity of cyclophosphamide following cytoreduction surgery of C-1300 neuroblastoma is mediated by both pharmacological and immunological mechanisms.

Inhibition of mammalian polyadenylate polymerase by 2-aza-1,N6-etheno-adenosine triphosphate.

2-Aza-1,N6-etheno-adenosine triphosphate (aza-epsilonATP), a fluorescent analog of adenosine triphosphate, significantly inhibits polyadenylate [poly(A)] polymerase of bovine lymphosarcoma and calf thymus, with 50% inhibition at 200 muM (in the presence of an equal concentration of adenosine triphosphate). Calf thymus RNA polymerases II and III are inhibited 32 and 20%, respectively, by a 3.8-fold excess of aza-epsilonATP; DNA polymerase alpha is not inhibited. The inhibition of poly(A) polymerase by aza-epsilonATP appears to be competitive with adenosine triphosphate; incorporation of aza-epsilonATP is not observed. Polymers of 2-aza 1,N6-etheno-adenosine monophosphate are used as primers, but pootly. 1,N-Etheno-adenosine triphosphate and 9-beta-D-arabinofuranosyladenine triphosphate are poor inhibitors of poly(A) polymerase; adenosine diphosphate is ineffective. Deoxyadenosine triphosphate inhibits to the same extent as aza-epsilonATP, while other naturally occurring nucleotides inhibit poly(A) polymerase to varying degrees, with deoxynucleoside triphosphates more potent than ribonucleoside triphosphates. Inhibition of poly(A) polymerase by naturally occurring nucleoside triphosphates suggests that nucleotides may regulate the enzyme in vivo; inhibition by the fluorescent analog aza-epsilonATP suggests that this compound may be useful in elucidating poly(A) metabolism in both normal and neoplastic cells.

5'-nucleotide phosphodiesterase isoenzyme in patients with hepatitis B infection.

The hypothesis that hepatitis B infection is etiologically related to hepatoma has been investigated by studying the interrelationships between hepatitis B surface antigen (HBsAg, Australia antigen) and the fast-moving 5'-nucleotide phosphodiesterase Band V isoenzyme (5'-NPDase-V). Sera from 58 patients with viral hepatitis were tested for 5'-NPDase-V and HBsAg. The isoenzyme was found in 34 of 37 patients who were also positive for HBsAg but in only 4 of 21 hepatitis patients who were HBsAg negative. Five patients convalescing from hepatitis were negative for both HBsAg and the isoenzyme. Preparative gel electrophoresis showed that these 2 markers were different proteins. Of 34 hepatoma patients, 29 were positive for 5'-NPDase-V. Only 1 isoenzyme-positive patient was positive for HBsAg by counterimmunoelectrophoresis. However, of 16 isoenzyme-positive hepatoma patients available for radioimmunoassay, 8 were NBsAg positive (50%). None of 21 hepatoma samples tested for antibody to NBsAg was positive. Of 21 "normal" carriers of HBsAg and 10 carriers with Down's syndrome, 4 persons were detected with the isoenzyme. The results suggest that HBsAg and 5'-NPDase-V in the presence of liver damage are associated and thus provide a new marker enzyme between hepatitis B infection and hepatoma.

Synthesis of aziridinylallylaminophosphine oxides and sulfides as potential adjuvant cancer chemotherapeutic agents.

Bis (1-aziridinyl)(hexahydro-1H-azepin-1-yl)phosphine sulfide, an active anticancer agent with low hematopoietic toxicity in animals and man, was recommended several years ago for breast cancer adjuvant chemotherapy as an alternate drug to thiotepa. This hope had led to the syntheses of aziridinylallylaminophosphine oxides or sulfides (compounds I-XVII) in our laboratories. The resurgent interest in this area of cancer chemotherapy encouraged us to report our synthetic work as well as their evaluation as both anticancer agents and insect chemosterilants. Based on observed antitumor activity in animals, low chemosterilant activity in female species (insects and rats), and histochemical observation of tissue toxicity in rat testes but not in ovaries, these new agents are of potential interest to the breast cancer adjuvant chemotherapy program.

Anti-tumor effect of (S)-10-hydroxycamptothecin on mouse hepatoma BW7756 and its possible mode of action.

(S)-10-Hydroxycamptothecin (OPT), an analog of camptothecin (CPT), was found to inhibit the growth of the mouse hepatoma BW7756, when given at 1.0 mg/kg/day for 14 days. Cell cycle studies using flow cytofluorometry indicated that this drug inhibited the S-Phase of the tumor cells in vivo and the S and G2/M phases in vitro. Similar studies on host liver showed little or no effect. In spite of the narrow range of the effective dose of this drug against mouse hepatoma BW7756, the use of OPT in combination with other antitumor agents may be useful in primary hepatoma or liver metastases in view of its low toxicity towards host liver. A simple cytofluorometric method useful for live cell cycle study has been adapted for this investigation and can be adopted for other drug studies.

Serum 5'-nucleotide phosphodiesterase as a predictor of hepatic metastases in gastrointestinal cancer.

Isoenzyme V of 5'-nucleotide phosphodiesterase (5'-NPD-V) is present in the peripheral sera of patients with hepatic metastases. A total of 122 patients underwent prospective serologic analysis followed by operation for primary tumors of the gastrointestinal tract and careful evaluation of the liver. A positive 5'-NPD-V assay was found in fifty-nine of sixty patients with liver metastases. A negative 5'-NPD-V assay was found in forty-three of sixty-two patients with no evidence of hepatic metastases. The accuracy of the test was 84 per cent, and the predictive value was 75 per cent. Serum 5'-NPD-V was abnormal significantly more frequently in patients with metastatic liver disease than were liver scans or carcinoembryonic antigen (CEA), alpha fetoprotein, serum glutamic oxalacetic transaminase (SGOT), and total serum bilirubin or serum alkaline phosphatase levels.

Facile preparation of 6-chloro-9-amino-2-hydroxyacridine, a urinary metabolite of quinacrine and quinacrine mustard.

6-Chloro-9-amino-2-hydroxyacridine was found to be a metabolite of both quinacrine and the antimalarial alkylating agent quinacrine mustard. Its structure was confirmed by a one-step reaction of quinacrine with 48 percent hydrobromic acid. The presence of this compound as a metabolite of quinacrine mustard suggests a possible in vivo activation mechanism for its antitumor activity and a pharmacological basis for its toxicity to the liver. In vitro experiments showed that this new compound does react with chromosomes and, therefore, can be both a useful chromosome stain and an intercalating agent.

Perfusion and molecular modification of idoxuridine to alter its cerebrospinal fluid metabolism.

Two methods to deter the rapid intrathecal degradation of idoxuridine were investigated: (a) rapid drug perfusion through the ventricular system, and (b) modification of the molecule to its uronic acid derivative, 2'-deoxy-5-iodo-5'-uridinecarboxylic acid, to make it less susceptible to enzymatic digestion. Perfusion of idoxuridine through the ventricular system (ventriculocisternal) of dogs at 0.97 ml/min saturated the metabolic pathway so that the outflow solution yielded a single spot (Rf 0.76) on TLC indicative of the intact molecule. The 125I-labeled uronic acid was synthesized from the 125I-labeled parent compound, and the labeled compounds were compared after their individual intracisternal injection in dogs. Since there was no difference in the disappearance rates, the stability of the uronic acid was, in fact, no greater than that of the parent compound in vivo. Ventricular perfusion of idoxuridine, however, seems a suitable means for increasing the amount of active drug delivered to central nervous system tumors and viral infections.

5'-nucleotide phosphodiesterase activity of floxuridine-resistant mouse glioma.

In tissue culture experiments, cells derived from glioma 26, a transplantable tumor of C57B1/6 mice, were sensitive to both floxuridine (5-fluorodeoxyuridine) and 5-fluorodeoxyuridine-5'-(5-iodo-3-indolyl)phosphate, an enzyme-mediated drug activated by 5'-nucleotide phosphodiesterase. When these compounds were tested on the tumor in animals at a level of 5 mg/kg for 5 days, tumor growth was inhibited approximately 20% by both compounds. When higher levels of 5-fluorodeoxyuridine, 100 mg/kg four times weekly throughout the lifespan of the mouse, were given, the tumor, although inhibited at first, developed resistance and continued to grow until it killed the animal. Phosphodiesterase levels in the tumor rose as the tumor grew. On the other hand, thymidine kinase levels dropped as anticipated from the known 5-fluorodeoxyuridine-resistant hepatoma tissue culture data. This enzyme pattern was maintained in transplantable mouse glioma lines established from the resistant tumors. One of these lines, tested at a level of 5 mg/kg for 5 days, showed no response to 5-fluorodeoxyuridine but was still sensitive to 5-fluorodeoxyuridine-5'-(5-iodo-3-indolyl) phosphate. These experiments, therefore, offer a model system and a rationale for the design and study of more compounds that could be activated by the enzyme phosphodiesterase. Such compounds might be used alternatively when resistance to 5-fluorodeoxyuridine develops, a common clinical experience in the use of this anticancer drug.