Low-molar-mass oat beta-glucan impacts autophagy and apoptosis in early stages of induced colorectal carcinogenesis in rats

Oat beta-glucan is one of the soluble dietary fibre fractions with a wide spectrum of biological activities such as anti-inflammatory and anti-tumour properties. In the present study, the effect of low-molar-mass oat beta-glucan isolate (O13Gl) on the level of autophagy and apoptosis in the colorectum of rats with induced early stages of colorectal cancer was investigated. Forty-five male Sprague-Dawley rats were divided into two main groups: control and azoxymethane-induced early-stage colorectal carcinogenesis (CRC). Both groups were divided into three dietary subgroups fed standard feed without O13Gl (O13Gl- ), with 1 % of O13Gl (O13Gl+1 %) or with 3 % of O13Gl (O13Gl+3 %). The expression of autophagy (LC3B, beclin-1) and apoptosis (caspase-3, cleaved caspase-3, BAX, BCL-2 and PARP-1) markers was determined by immunohistochemistry, Western blot and PCR analysis. The obtained results showed that the expression of LC3B, caspase-3 and cleaved caspase-3 in the CRC mucosa, and LC3B-II expression in the CRC wall were higher in the O13Gl+3 % compared to the O13Gl- rats. A higher BAX/ BCL-2 ratio was also observed in the CRC O13Gl+1 % rats compared to the other CRC animals. In summary, O13Gl+3 % has a modulatory effect, stimulating autophagy and the extrinsic apoptosis pathway, while O13Gl+1 % has a stimulatory effect on the intrinsic apoptosis pathway.