Atm heterozygous deficiency enhances development of mammary carcinomas in p53heterozygous knockout mice

Breast Cancer Research

Table 2 Incidence of tumours in irradiated (BALB/cHeA × MSM/Ms) F₁ female mice that were heterozygously deficient for p53 and/or Atm genes

Genotypes	p53^+/-		p53 ^+/+
	Atm ^+/- (n = 55)	Atm ^+/+ (n = 61)	Atm ^+/- (n = 47)	Atm ^+/+ (n = 53)
Mammary carcinoma	32 (58%)^a*	19 (31%)	0 (0%)	1 (2%)
Lymphoma	24 (44%)^b	29 (48%)	26 (55%)	22 (42%)
Squamous cell carcinoma	1 (2%)	1 (2%)	0 (0%)	0 (0%)
Histiocytic sarcoma	1 (2%)^c	0 (0%)	0 (0%)	0 (0%)
Basal cell carcinoma	0 (0%)	1 (2%)	0 (0%)	0 (0%)
Granulocytic leukaemia	0 (0%)	1 (2%)	0 (0%)	0 (0%)
Ovarian carcinoma	0 (0%)	1 (2%)	0 (0%)	0 (0%)
Nonthymic lymphoma (NOS)	0 (0%)	1 (2%)	3 (6%)	0 (0%)
Solid tumour (NOS)	1 (2%)^d	1 (2%)^e	1 (2%)	1 (2%)
Number of mammary carcinomas/mouse^e	52/55 (0.95)**	28/61 (0.46)	0/47 (0.00)	1/53 (0.02)

^aNumber of mice with tumours; percentage in parenthesis is the proportion of mice developing mammary carcinoma. ^bThree animals developed both lymphomas and mammary carcinoma. ^cOne animal developed both histiocytic sarcoma and mammary carcinoma. ^dTumour in abdomen. ^eTotal number of mammary carcinomas developing in mice with given genotypes/number of mice examined; numbers in parentheses are average numbers of tumours per mouse. *The proportion of mice developing tumours is significantly greater than that in p53 ^+/- Atm ^+/+ mice (P = 0.0034 by c² test). **The average number of tumours/mouse is significantly greater than that in p53^+/- Atm ^+/+ mice (P = 0.0052 by Mann–Whitney U-test). NOS, not otherwise specified.

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