A CRITICAL STUDY OF VITAMIN A AND CARCINOGENESIS

Transcription

1 A CRITICAL STUDY OF VITAMIN A AND CARCINOGENESIS KANEMATSU SUGIURA AND STANLEY R. BENEDICT (From tha Huntington Fund for Cancer hearch, Memorial Hoepitcrl and the Hamman Raearch Fund, New York) In recent years some interest has arisen concerning the influence of a dietary deficiency of vitamin A in the production of tumors in rats. Fuzimaki and his associates (1, 2, 3) reported that prolonged feeding of rats with a diet deficient in vitamin A was followed by the development of carcinoma in the fore-stomach of five rats out of 49 animals tested. One of the five animals developed metastases in the lungs. Their recent communication (4) indicated that the hyperkeratosis or atypical epithelial proliferation in the fore-stomach of albino rats was not marked unless the animals were fed with a diet deficient in' fat, as well as in vitamin A. The investigations of Erdmann and Haagen (5) also lead to the conclusion that lack of vitamin A in the diet is an important factor in carcinogenesis. Following special feeding they found a number of rats with spontaneous tumors. Of the 83 specially fed rats, 6 developed tumors. Four tumors originated from the mammary gland of female animals. Three of the tumors were adenocarcinomas, and one was an angioma. Two other tumors were papillomas of the stomach. They stated that the great increase over the control animals (7 per cent against less than 1 per cent) could only be accounted for by the kind of diet eaten (6). In her last paper (7) Erdmann stated that after being subjected to a diet over-rich in vitamin B and D, eight rats in three series of experiments developed malignant growths. In the firat aeries, consisting of 80 rats, 3 adenocarcinomas of the mammary gland developed (5). In the second series, consisting of 100 rats, one papilloma of the stomach appeared. 308

2 The nature of four other growths was not mentioned in her paper. Control animals in equal numbers did not develop tumors. A critical study of Cramer (8) on the same subject showed negative results. Furthermore, he stated that warts or papillomas frequently occur in the fore-stomach of old rats which have received an adequate amount of vitamins. In 1919, McCarrison (9) reported the occurrence of an early carcinoma of the pylorus in a monkey fed for 51 days on food almost wholly devoid of vitamin B. Complete autopsies made by Tilden and Miller (10) on 11 monkeys maintained for a long period on a vitamin A deficient diet failed to reveal any sign of tumor formation. These same authors reported, however, that epithelial metaplaaia waa found in one or more tissues in 9 of the 11 animals. One of us (11) reported finding a new transplantable rat sarcoma which developed in one of the animals kept for a long period on a complete diet but limited in quantity to one third of the normal food requirement. On account of the low incidence of occurrence we did not consider this tumor formation related to the under-feeding. In view of the facts that the rate of growth of transplanted tumors in animals fed with a diet deficient in vitamins (12) is significantly reduced; and that the prolonged postoperative insufficient feeding causes marked reduction in the frequency of recurrences of spontaneous mammary carcinoma in mice (13); and because of the conflicting reports from different countries concerning the influence of diet on carcinogenesis, we felt that it would be worth while to investigate the positive findings of Fuzimaki and others. EXPERIMENTAL Our experiments were begun in the early part of 1928 and extended over about 18 months. We employed one of the Fuzimaki's vitamin A-free diets for the experimental diet. This diet has the following composition: casein 18 per cent, dextrin 66 per cent, olive oil 10 per cent, salt mixture 4 per cent, and yeast 2 per cent.

3 Casein and dextrin were purified by our alcohol method (14). The salt mixture was prepared according to Fuzimaki and his associates (2). Fresh Fleishmann's yeast waa dried in the air at room temperature and was then well ground. Traces of vitamin A in olive oil were completely destroyed by heating and simultaneous aeration. After preliminary feeding experiments with the above vitamin A-free diet, we found that young albino rats, 28 to 30 days old, grew but little after a slight drop in body weight during the first week due to the changing from a common diet of whole wheat bread, milk and lettuce. Animals on the vitamin A-free diet do not live very long. The average length of life of a group of 24 rats was 56 days; some, however, died as early as 30 days, while others lived 70 days on the ration. The average gain in body weight during that period was 8.3 grams. The general condition of these animals was very poor. About 50 per cent of them showed eye infection (xerophthalmia). Rats living on our regular diet for a longer period of time prior to the regime of vitamin A-free ration were found to require much longer periods to produce the same symptoms due to their own vitamin A reserves. Thus 8 young rats, 44 days old, maintained apparent normality on the vitamin A-free diet for periods of 100 to 127 days before showing any evidence of the deficiency disease. Since the animals vary greatly in their response to this deficiency disease, we have not changed their diet to one containing 10 per cent of butter fat until the animals showed marked ill effects. The amount of butter fat then replaced an equal quantity of dextrin in the diet. Feeding with a ration containing butter fat was continued for 7 to 19 days. During this period most of the animals recovered their normal health. Again the animals were placed on the vitamin A-free diet and the preceding procedure was repeated until the termination of the experiments. Young albino rats ranging from 28 to 60 days old were selected for the present study. It is evident that the number and duration of the vitamin A ration vary in different groups. In some groups, the animals

4 A STUDY OF VITAMIN A AND CARCINOQENESIS 309 were entirely on a vitamin A-free diet for over 100 days; while in others, there wa. only a 30 day regime of the deficient diet. In a total of 108 experimental rats, 42 animals lived 30 to 141 days on a vitamin A-free diet only, and the other 66 animals lived 100 to 475 days on the same diet with intermittent substitution of one containing vitamin A. Preliminary gross examination was made of the stomach, visceral organs, and subcutaneous tissues of 108 experimental rats after death or killing with anesthesia. The tissues were then fixed in formalin for histological examination.' The results obtained from the present investigation may be summarized as follows : 1. Of the 108 rats, two female rats developed spontaneous tumors, one an adenocarcinoma of the mammary gland, and the other a fibroadenoma of mammary gland origin. The finding of spontaneous tumors in about 2 per cent of the specially fed animals does not in our opinion warrant a conclusion that the diet employed was a causative factor. 2. There was no evidence of tumor development in the viscera of rats kept a long period on a vitamin A deficient diet. 3. We have failed to observe any tumor formation in the forestomach or in other parts of the stomach of rats fed on the special artificial diets. A microscopical examination of tissues showed some changes in the esophagus and cardia, namely, keratinization of the outer strata of epithelium. Although certain changes were found among some of the normally fed animals, the frequency and extent of the keratinization of the fore-stomach appear to be relatively greater in the specially fed animals than in the normally-fed controls. Several investigators (10, 15, 16) have already pointed out that in rats atrophy, metaplasia and keratinizing epithelium in a number of organs and tissues will develop as a result of a dietary deficiency of vitamin A. 4. The stomachs of these specially-fed animals were greatly diminished in size. Many of them weighed only from one We are very much indebted to Dr. Fred W. Stewnrt for the histological examination of sections of the stomache.

5 half to one third as much as the normal. The histological examinations of sections of these stomachs showed in general a normal structure; some other sections showed keratinization. The experiments reported herein indicate that the prolonged feeding of a vitamin A deficient diet to rats has no apparent influence on tumor genesis in these animals. REFERENCES 1. F~ZIMAKI, Y., AND MABAKI, M.: Trans. 6th Cong. Far Eaatern Assn. Trop. Med., Tokyo, 1925, FUZIMAKI, Y., K~URA, T., WADA, Y., AND SHIMADA, S.: Gann, 1926, xx, 261; 1927, xxi, F~Z~MAKI, Y.: J. Cancer Rea., 1926, x, FUZIMAKI, Y., KIMURA, T., WADA, Y., AND SHIMADA, S.: Gann, 1929, xxiii, ERDMANN, RH., AND HAAQEN, E.: Zeit. f. Krebsforch., 1928, xxvi, ERDMANN, RH., AND HAAQEN, E.: Verhand. d. deutch. Gea. f. inn. Med., x Kong., Wiesbaden, 1928, ERDMANN, RH.: Report Intern. Confer. Cancer, London, 1928, CRAMER, W.: 26th Ann. Report Imp. Cancer Rea. Fund., England, 1928, MCCARRIBON, R.: Indian J. Med. Ree., 1919, vii, TILDEN, E. V., AND MILLER, E. G.: Dissertation, Columbia University, SUQIU~, K.: J. Cancer Rea., 1928, xii, SUQIUU, K., AW BENEDICT, S. R.: J. Cancer Rea., 1920, v, Suamm, K., AND BENEDICT, S. R.: J. Cancer Rea., 1926, x, SUQIURA, K., AND BENEDICT, S. R.: J. Biol. Chem., 1919, xl, MORI, S.: Bull. Johns Hopkins Hosp., 1922, xxxiii, GOLDBIAIT, H., AND BENIBCBEK, M.: J. Exper. Med., 1927, xlvi, 699.