Susceptibility of Mouse Strains to Lung Tumor and Sarcoma Induced by 1:2:5:6-dibenzanthracene

Abstract

It has been shown that strains of mice differ in their inherited susceptibility to tumors both spontaneous and tar-induced. 1 Burrows, Hieger and Kennaway 2 and others have demonstrated the effectiveness of 1:2:5:6-dibenzanthracene in inducing sarcoma. The present paper is a preliminary report on the tumors induced by subcutaneous injection of 1:2:5:6-dibenzanthracene into various strains of mice.

Ordinary lard was filtered at 37°C. and the crystalline dibenzanthracene was dissolved in the filtrate by reheating to 140°C. Each mouse received a total dose of 4 mg. of 1:2:5:6-dibenzanthracene in 1 cc. of lard administered in 3 subcutàneous injections of 0.25 cc., 0.25 cc., and 0.5 cc. at biweekly intervals.

Of the mice receiving treatment 2 groups were from our branch of the Bagg albino strain. The 3rd was from our “Yellow” strain which is only pen inbred and probably not very homogeneous genetically but interesting because it produces yellow and brown mice. A 4th was from No. 1194—our highly inbred agouti or wild type strain; a 5th from Strain 5—an imported albino stock from McGill University. The 5th contained males only. The 6th was from Strain 62 which is composed of pink-eyed dilute brown mice, highly inbred brother by sister. Another group of Bagg mice from a previous experiment may be legitimately included for discussion here.

The results are shown in Table I. The presence of lard makes it difficult to determine the time when malignancy supervenes in the injected tissue, and lung tumors are found only at autopsy. Therefore the percentages are based upon the populations surviving at the time the presence of the first tumor of each type was proven by microscopic sections. For the lung tumor, this date was the 66th day after the last injection; for the sarcoma, the 73rd day. No mice lived longer than 376 days after treatment, the majority less than 200 days. The table lists the subcutaneous sarcomas occurring at the site of injection and primary lung tumors of epithelial origin.