Azoxymethane

Cell lines

hepatic microsomes

Preparation Method

The assay for AOM-induced in vitro DNA adduct formation was based on a published method. Briefly, microsomes (0.5-2.0 mg/mL) were incubated with calf thymus DNA (1 mg/mL) and AOM (200 µM) in a total volume of 1.0 mL. The assay buffer consisted of 0.1 M Tris-HCl (pH 7.4), 1 mM EDTA, 20 mM MgCl2, 0.3 M KCl, and 1.5 mM NADPH. Incubations were carried out at 37 °C for 60 min in a shaking water bath. An additional 30 nmol of NADPH was added after the first 30 min. The reaction was stopped by the addition of 0.5 mL of ice-cold 7.5 M ammonium acetate. DNA was then extracted as described above for tissue homogenates. Control incubations were performed without NADPH.

Reaction Conditions

200 µM; 60 min

Applications

On an equal protein basis, hepatic microsomes were much more active than SI and colon microsomes in NADPH-dependent AOM bioactivation and N7-mG adduct formation. Microsomes of the liver (but not those of the SI or colon) of LCN mice showed significantly lower activity in N7-mG formation compared to that of WT mice.

Animal models

8 to 10-week-old male C57BL/6J mice

Preparation Method

On day 0, mark and weight each mice. Prepare 1 mg/mL (1 µg/µL) AOM working solution in PBS, and inject each mouse intraperitoneally with 10 mg/kg (body weight) of AOM (For example, a 20 g mouse shall be injected with 200 µL AOM solution). Then each mice was providedwith 2.5% DSS-containing drinking water for 7 days, followed with normal water for 10 days. This cycle of DSS -containing water and normal water shall be repeated three times, and then the normal water treatment stays last to the experimental endpoint.

Dosage form

10 mg/kg, i.p.

Applications

The colitis-associated CRC (colorectal cancer) model in mice can be made by using AOM and DSS. AOM- and DSS-induced murine colorectal cancer model has a body weight dynamics. DSS administration could cause significant weight loss.

References:

[1] Megaraj V, et al. Role of hepatic and intestinal p450 enzymes in the metabolic activation of the colon carcinogen azoxymethane in mice. Chem Res Toxicol. 2014 Apr 21;27(4):656-62.
[2] Sun W, et al. Protocol for colitis-associated colorectal cancer murine model induced by AOM and DSS. STAR Protoc. 2023 Mar 17;4(1):102105.