R. Preussmann

PATHOLOGY OF EXPERIMENTAL NEUROGENIC TUMORS CHEMICALLY INDUCED DURING PRENATAL AND POSTNATAL LIFE

Among the neoplasms of the human body, those of the nervous system belong in a special category, not in regard to the general characteristics of neoplastic growth but rather to the peculiarities dictated by the functional and morphological specificity and heterogeneity of the organ from which these tumors are derived. The complicated structural organization of the nervous system, compared with other organs, and its cellular and regional diversity explain the following characteristics of neurogenic tumors: wide range of morphological variability, inherent tendency toward infiltrative and destructive growth, variable growth rate without extraneural metastasis, close relationship between type of neoplasm and the site at which it generally occurs, and ageand sex-dependent incidence. One can safely state that the classical, morphology-oriented research in human neurooncology, with the attempt to describe and classify brain tumors in detail, has come to an end, although there are still some unresolved differences of opinions regarding tumor classification (Ziilch, 1948, 1956, 1965; Kernohan & Sayre, 1952; Henschen, 1955; Russell & Rubinstein, 1963; Polak, 1966; Zulch & Wechsler, 1968). Experimental neurooncology is essential, since fundamental questions regarding etiology and pathogenesis of human neurogenic tumors are still unanswered. A thorough knowledge of the characteristics of human neurogenic tumors is, however, a necessary prerequisite for the direction of experimental research and for the proper comparative evaluation of the results obtained by experimental means. This monograph is entitled “Research in the Experimental and Clinical Aspects of Brain Tumors.” Therefore, we decided to give preference in this paper to results obtained from experimental neurooncology. Special emphasis is placed on a new model dealing with resorptive carcinogens, developed in Professor Druckrey’s department,

N-NITROSO COMPOUNDS IN ORGANOTROPIC AND TRANSPLACENTAL CARCINOGENESIS*

For a proper judgment of the potential role of chemical substances in human carcinogenesis, it is essential to know whether cancer can be induced in every organ of experimental animals, and whether these neoplasias are comparable to the corresponding tumors in man. The answer to these questions requires systematic studies, in which the problem of specificity is fundamental. Organotropic effects (i.e., specific effects upon a certain organ) can best be attained with compounds that are inactive as such but that become activated by metabolic changes (“indirect” carcinogens). This applies to dimethylnitrosamine (Magee & Barnes, 1956), and similarly to the carcinogenic hydrazo-, azo-, or azoxyalkanes, and to l-aryl-3,3-dialkyltriazenes. The first experiments of Dutton and Heath (1956) showed that dimethylnitrosamine becomes demethylated enzymatically mainly in the liver, and leads to diazomethane as the active alkylating carcinogen. For biochemical reasons, however, we Came to the conclusion that the first step of activation is an enzymatic hydroxylation on an (alpha) aC-atom (Druckrey et al., 1961a). This should be possible in all dialkylnitrosamines possessing at least one disposable hydrogen atom in alpha position. The ac-hydroxyalkylnitrosamine then becomes dealkylated spontaneously to the corresponding monoalkylnitrosamine, which, by protonic change, yields the isomeric diazohydroxide, as explained in the formulas of FIGURE 1. Both these intermediates are extremely unstable and yield diazoalkane, diazotate, or alkyldiazonium, depending upon conditions. The latter is highly reactive. It can lead to diazotization, or decomposes rapidly to gaseous nitrogen and the respective alkyl-cation, which most probably is the ultimate “alkylating” carcinogen (Magee & Barnes, 1967). According to this “alkylation theory” of carcinogenesis, the activation of dialkylnitrosamines passes several steps, among which the initial aC-hydroxylation is the only enzymatic process. This, however, can lead to organospecific effects, as first shown with the liver carcinogen dimethylnitrosamine by Magee and Barnes (1956). In contrast to dialkylnitrosamines, the acylalkylnitrosamides react by heterolysis. Therefore, many of them are widely used in chemistry for the production of diazoalkanes and for alkylations. After heterolysis, the further degradation pathways are the same as with dialkylnitrosamines. Both groups represent the class of N-nitroso compounds.

Cancerogene alkylierende Substanzen@@@Cancerogenic alkylating substances. III. Alkyl-halogenides,-sulfates,-sulfonates and strained heterocyclic compounds: III. Alkyl-halogenide,-sulfate,-sulfonate und ringgespannte Heterocyclen

Twelve direct alkylating substances, which were selected according to their chemical reactivity against 4-nitrobenzyl-4-pyridine (NBP) or their practical use, were tested for cancerogenic activity in 535 BD-strain rats. Subcutaneous injections once a week of methyl iodide, benzylchloride, dimethyl- and diethyl-sulfate, methyl methanesulfonate, p-toluenesulfonic acid methylester, and trimethylene oxide respectively produced local sarcomas, the yield corresponding to dosage. With di-n-butylsulfate, p-toluenesulfonic acid ethylester and ethylene sulfide only a few tumours were observed. Veratryl chloride and p-toluenesulfonic acid n-butylester were not cancerogenic. When given by oral route or by intravenous injections, even dimethyl- and diethyl sulfate were inactive. Inhalation of dimethyl sulfate vapours, 3 and 10 ppm respectively for one hour five times per week, however, produced squameous carcinomas of the nascal cavity or neurogenic tumours in 8 out of 27 exposed rats. In transplacental experiments one single dose of dimethyl- and diethyl-sulfate respectively was injected to pregnant rats at the 15 th day of gestation. Seven out of 59, and 2 out of 30 rats of the offspring developed malignant tumours, mostly of the nervous system. Zwölf direkt alkylierende Substanzen, die nach ihrer chemischen Reaktivität gegenüber 4-Nitrobenzyl-4-pyridin (NBP) oder nach ihrer praktischen Bedeutung ausgewählt waren, wurden auf cancerogene Wirkung an insgesamt 535 BD-Ratten geprüft. Subcutane Injektionen einmal wöchentlich von Methyljodid, Benzylchlorid, Dimethyl- und Diäthylsulfat, Methylmethansulfonat, p-Toluolsulfonsäure-methylester sowie von Trimethylenoxid erzeugten lokale Sarkome. Die Ausbeuten entsprachen der Dosierung. Mit Di-n-butylsulfat, p-Toluolsulfonsäure-äthylester und Äthylensulfid wirden nur wenige Tumoren beobachtet. Veratrylchlorid und p-Toluolsulfonsäure-n-butylester waren nicht cancerogen. Bei oraler Gabe oder intravenöser Injektion erwiesen sich selbst Dimethyl- und Diäthylsulfat als praktisch inaktiv. Die Inhalation von Dimethylsulfat-Dämpfen mit 3 bzw. 10 ppm für jeweils eine Stunde an 5 Wochentagen führte dagegen bei 8 von 27 Ratten zu Plattenepithelcarcinomen der Nasenhöhle oder zu neurogenen Malignomen. In transplacentaren Versuchen erhielten schwangere Ratten am 15. Tage nach dem Coitus eine einmalige Injektion von Dimethyl- bzw. Diäthylsulfat. Sieben von 59 bzw. 2 von 30 Nachkommen, entwickelten maligne Tumoren, meist im Nervensystem.

Neurotrope carcinogene Wirkung von Phenyl-dimethyl-triazen an Ratten

Diese E r s c h e i n u n g e n k 6 n n e n ihre Erkl i i rung i m W i r k u n g s m e c h a n i s m u s des 5 -FU auf die D i S u n d R N S S y n t h e s e finden, U n t e r s u c h u n g e n darf lber s ind in Vorbere i tung . E ine ausf i ihrl iche Dars t e l lung auch m i t kombin i e r t e r R 6 n t g e n b e s t r a h lung wird an ande re r Stelle erfolgen. Mi t U n t e r s t f i t z u n g der D e u t s c h e n F o r s c h u n g s g e m i n s c h a f t .

Carcinogene Wirkung von 13 Aryldialkyltriazenen an BD-Ratten

Investigation in BD-rats of 13 1-aryl-3,3-dialkyltriazenes demonstrated a potent carcinogenic activity in 10 triazenes. Single dose application in many cases also induced tumors. Malignancies were observed in many organs, a certain preference for brain, nervous system and kidney, however, is evident. The possibility is discussed that triazenes react in vivo according to their chemical reactivity by two different mechanisms, either as diazotising and/or arylating agents or as alkylating agents after enzymatic activation. Bei der Untersuchung von 13 1-Aryl-3,3-dialkyltriazenen zeigten 10 Triazene starke carcinogene Wirkung an BD-Ratten. Die Tumoren traten in vielen Organen auf, mit gewisser Bevorzugung von Gehirn, Nervensystem und Niere. Es wird diskutiert, daß carcinogene Triazene je nach chemischer Reaktivität entweder als diazotierende und/oder arylierende oder aber nach metabolischer Aktivierung als alkylierende Agentien ihre Wirkung entfalten können.

Transplacentar induction of neurogenic malignomas by 1,2-diethyl-hydrazine, azo-, and azoxy-ethane in rats

Schwangere Ratten erhielten am 15. Tage post coitum eine einmalige i.v. Injektion von 1,2-Diäthyl-hydrazin bzw. von Azoxyäthan oder wurden einmal 1 h lang Azoäthan-Dämpfen exponiert. 107 von 114 aufgezogenen Nachkommen starben mit malignen Tumoren im Gehirn, Rückenmark und peripheren Nervensystem.

Erzeugung von Magen- und Pankreas-Krebs beim Meerschweinchen durch Methylnitroso-harnstoff und-urethan

Methylnitroso-urea and-urethane, which induced carcinomas of the forestomach in rats after oral administration, have been tested in guinea pigs, since their stomach is glandular, like that of man. Both compounds were given in the drinking water 5 days weekly at a dosage of 2.5 mg per kg body weight. Methylnitroso-urea(I) produced malignant tumours in 12 out of 26 surviving guinea pigs and methylnitroso-urethane(II) in 27 out of 38. The medium induction time was 800 and 740 days respectively, and the localisation of the tumours was similar in both experiments. We observed 16 carcinomas and 2 sarcomas of the stomach, and 16 carcinomas of the pancreas, in 9 cases with metastases in other organs. In addition, with (I) one neurinoma, 2 malignant tumours of the ear duct, and 2 leucemias were obtained; with (II), one carcinoma of the lung and one of the larynx. The mechanism of action is briefly discussed. Methyl-nitroso-harnstoff (MNH) und Methyl-nitroso-urethan (MNUT), die nach oraler Gabe an Ratten Carcinome des Vormagens erzeugt hatten, wurden an Meerschweinchen geprüft, weil diese Tierart, ähnlich wie der Mensch, nur einen Drüsenmagen besitzt. Die Applikation erfolgte im Trinkwasser an jeweils 5 Tagen in der Woche mit einer Dosierung von 2,5 mg pro kg. Im Versuch mit MNH beobachteten wir bei 12 von 26 überlebenden Meerschweinchen maligne Tumoren und mit MNUT bei 27 von 38 Tieren. Die mittlere Induktionszeit betrug 800 bzw. 740 Tage. Die Lokalisation der Tumoren war in beiden Fällen ähnlich. Im ganzen fanden wir 16 Fälle von Carcinomen und 2 von Sarkomen des Magens sowie 16 Tiere mit Pankreas-Krebs. Metastasen in anderen Organen wurden in 9 Fällen beobachtet. Ferner erhielten wir nach MNH 1 Neurinom, 2 Malignome des Gehörgangs und 2 Leukämien sowie nach MNUT je einen Fall von Lungenkrebs und Larynx-Carcinom. Der Wirkungsmechanismus wird kurz diskutiert.

Krebserzeugung durch einmalige Dosis von Methylnitrosoharnstoff und verschiedenen Dialkyl-nitrosaminen

die Gelegenhei t , die oben gestel l te F rage zu s tud ieren . Diese S u b s t a n z is t eine au f s y n t h e t i s c h e m W ege m i t f reien SHG r u p p e n subs t i t n i e r t e Gelat ine, die Ieicht wasser l6s l ich nach O x y d a t i o n dieser f re ien Su l fhyd r i l g ruppen infolge Vern e t z u n g in der Molekel die o_ a. E i g e n s c h a f t e n erhfilt. Der Ante i l dieses Thiogels an freien S H G r u p p e n i s t m a g a n a l y t i s c h b e s t i m m b a r . L 6 s u n g e n dieser S u b s t a n z w u r d e n e r w a c h s e n e n lViXusen ( S t ~ m m e C 3 H n n d C57B1, beiderlei Geschlechts , t 2 t 6 W o c h e n alt) in def in ie r ten M e n g e n y o n je t50 m g / m l W a s s e r jeweils 4, 2 u n d 1/2 S td vor R 6 n t g e n b e s t r a h l u n g mi t t e l s Sch lundsonde (bes tehend aus In j ek t ionssp r i t ze m i t aufgezogenem, we i chem u n d d f i nnem Po lyv iny l r6hrchen) verabre ich t . B e s t r a b l a n g s d a t e n : ~ g0 kV, 20 mA, Ti l ter 0,2 m m Ca, F H A 53 cm, Dos i s l e i s tung 85 r /min, e m p f a n g e n e Dosen t050 a n d t400 r. I n gewissen Zei tabst~inden (24 Std bis 6 Tage) wird der D N S G e h a l t der Mucosa u n d die spezif ische Ak t iv i t~ t der i sol ier ten D N S b e s t i m m t . M ark i e rung der D N S in v ivo du rch i. p. I n j ek t i on yon 15 Mikr0cur ie ZH-Thymid in (360 Millicurie/IViillimol) jeweils 15 Std vor dent Tod des Tieres. Methodik der q u a n t i t a t i v e n D N S I s o l i e r u n g a n d B e s t i m m u n g s v e r f ah r en [s. 1)], in deren R a h m e n diese U n t e r s u c h u n g e n durchgef i ihr t w a r d e n a n d der s u c h die \ u ftir die ungesch i i t z t en Kon t ro l l en u n d m i t A E T i .p. b e h a n d e l t e n Tiere e n t n o m m e n sind. Die R e s u l t a t e m i t S t a n d a r d a b w e i c h u n g e n der verschiedenen Ve r snchs r e i hen s ind in der Tabel le angegeben .

Cancerogene alkylierende Substanzen

As examples of α-aminoalkylating substances, bis-(morpholino-)methane and in one case also bis-(N-methyl-anilino-)methane have been tested for carcinogenic activity. Subcutaneous injections in BD-strain rats mostly produced local sarcomas. In addition, one neurosarcoma of the sciatic nerve and one case of mammary carcinomas was observed. Bis-(morpholino-)methan und in einem Falle auch Bis-(N-methylanilino-)methan wurden als beispiele der α-aminoalkylierenden Substanzen auf carcinogene Wirkung untersucht. Die subcutane Injektion an BD-Ratten führte in fast allen Fällen zu lokalen Sarkomen. Darüber hinaus wurde auch ein Neurosarkom des Nervus ischiadicus und ein Fall mit Mammacarcinomen beobachtet.

Biotransformation von carcinogenen Dialkylnitrosaminen. Weitere Urinmetaboliten von Di-n-butyl- und Di-n-pentyl-nitrosamin

Three further urinary metabolites of di-n-butyl-nitrosamine and one further metabolite of di-n-pentyl-nitrosamine are described. A general scheme for biotransformations of dialkylnitrosamines is given. Drei weitere Urin-Metaboliten von Di-n-butylnitrosamin und ein weiterer Metabolit von Di-n-pentylnitrosamin werden beschrieben. Ein allgemeines Schema für die Biotransformationen von Dialkylnitrosaminen mittleren Molgewichts wird gegeben.