Influence of Breeding on Induction of Mammary Cancer with Methylcholanthrene in Strain Dba Female Mice.

Abstract

From t'he Departments of Anatomy, Radiology, and Phgsiology,S ~'~t i r c r s i t y of MinnesotaThe percutaneous administration of either 9,10dimethyl-l,2-benzanthracene or methylcholanthrene was reported by Engelbreth-Holm and Lefbvrel and Engelbreth-Holm* to accelerate the development of mammary cancer in female mice of strain Dba. Morton and Mider3v4 had previously treated similar mice in like manner, but had not described this phenomenon. The latter authors stated specifically3 that male and female animals were segregated, whereas Engellbreth-Holm made no definite statement in this regard. This possible difference in technic suggested to the present authors that breeding might condition the response to carcinogens insofar as development of mammary cancer was concerned. Another explanation for the discrepancy in the above findings could be th: use of different sub-lines of this strain of mice in the two investigations. I t was therefore decided to test the effect of breeding on the carcinogenic induction of mammary 'cancer within a single sub-line of strain Dba.O I t was first demonstrated that 23 out of 26 untreated breeding females of the sub-line

Induction of Breast Cancer by Oestrogens and Methylcholanthrene in High- and Low-Breast-Cancer Strain Mice

“…Experiments carried out by Mider and Morton (1939), Bonser and Orr (1939), Strong and Smith (1939), Bonser (1940), Strong and Williams (1941), Engelbreth-Holm (1941), Engelbreth-Holm and Lefevre (1941), Orr (1943), Kirschbaum, Lawrason, Kaplan and Bittner (1944), Kirschbaum, Williams and Bittner (1946), Shimkin and Bryan ), Strong (1945), Orr (1946, demonstrated that carcinogenic hydrocarbons induce the appearance of breast cancer in females of low-cancer strains or accelerate the development of breast tumours in female mice of high-cancer strains. In these experiments it was also shown that oestrogenic influence is important in the induction of breast cancer by carcinogenic hydrocarbons, since mice developing these tumours in the absence of treatment with oestrogens were females, with one exception, a CBA male (Orr, 1943).…”