Tumour formation in multiple intestinal neoplasia (Apc Min/+) mice fed with filtered or unfiltered coffee

Background The aetiology of colorectal cancer has strong dietary links, and there may be an association between coffee and colorectal cancer risk. Objective To study the effects of filtered (low levels of kahweol/cafestol) and unfiltered (high levels of kahweol/cafestol) coffee on tumour formation in multiple intestinal neoplasia (Apc Min/+) mice. Design Apc Min/+ mice (n=11 per group) were fed for 9 weeks with 10% w/w of these two types of coffee. Coffee was served as a dietary ingredient mixed with a semi-synthetic AIN-93G-based diet. Plasma levels of caffeine and paraxanthine were used as compliance markers. At the end of the feeding period intestinal tumour number and size were determined. The levels of β-catenin and cyclin D1, two cell-signalling proteins important to the progression of neoplasia, were also analysed in the tumour tissue. Results Plasma caffeine and paraxanthine concentrations were 3.2±1.4 and 1.7±0.4 µmol l−1 in the filtered coffee group and 3.6±2.3 and 1.6±0.6 µmol l−1 in the unfiltered coffee group. The level of plasma xanthines was below detection in the control group. The total number of tumours was equal between the dietary groups: 29 for the control, 30 (p =0.767) for the filtered coffee and 29 (p=0.430) for the unfiltered coffee groups. The levels of β-catenin and cyclin D1 in the nuclear fraction of the tumour tissue were also the same between the groups. Conclusions Filtered or unfiltered coffee (10% w/w) does not exert antitumorigenic activity in Apc Min/+ mice or change β-catenin and cyclin D1 signalling in the adenoma tissues. The results suggest that coffee does not change neoplasia progression in this animal model.