The glycan-binding protein galectin-1 controls survival of epithelial cells along the crypt-villus axis of small intestine.

Intestinal epithelial cells serve as mechanical barriers and active components of the mucosal immune system. These cells migrate from the crypt to the tip of the villus, where different stimuli can differentially affect their survival. Here we investigated, using in vitro and in vivo strategies, the role of galectin-1 (Gal-1), an evolutionarily conserved glycan-binding protein, in modulating the survival of human and mouse enterocytes. Both Gal-1 and its specific glyco-receptors were broadly expressed in small bowel enterocytes. Exogenous Gal-1 reduced the viability of enterocytes through apoptotic mechanisms involving activation of both caspase and mitochondrial pathways. Consistent with these findings, apoptotic cells were mainly detected at the tip of the villi, following administration of Gal-1. Moreover, Gal-1-deficient (Lgals1(-/-)) mice showed longer villi compared with their wild-type counterparts in vivo. In an experimental model of starvation, fasted wild-type mice displayed reduced villi and lower intestinal weight compared with Lgals1(-/-) mutant mice, an effect reflected by changes in the frequency of enterocyte apoptosis. Of note, human small bowel enterocytes were also prone to this pro-apoptotic effect. Thus, Gal-1 is broadly expressed in mucosal tissue and influences the viability of human and mouse enterocytes, an effect which might influence the migration of these cells from the crypt, the integrity of the villus and the epithelial barrier function.

[In vivo apoptotic effect of alpha-2b interferon (IFN) on rat preneoplastic liver ]. / Efecto apoptotico in vivo del interferon alfa-2b (IFN) sobre higados preneoplasicos de rata.

In order to know whether IFN alpha prevents in vivo oncogenesis in the very-early-stage cancer cells, we evaluated the action of IFN alpha-2b on preneoplastic foci in rats. Animals were divided into six groups: subjected to an initiation-promotion model of cancer development (G1), treated with IFN alpha-2b during: a) initiation-promotion (G2), b) initiation (G3), promotion (G4); subjected only to an initiation stage (G5) and treated with IFN alpha-2b during this period (G6). The number and area of rGST P-positive foci were reduced and the Apoptotic index was increased in G2, 3 and 6. Bcl-2 and Bcl-XL protein levels were decreased in IFN alpha-2b-treated rats. Increased levels of mitochondrial Bax protein were observed in G2, 3 and 6. In conclusion, preneoplastic hepatocytes in the IFN alpha-2b-treated rats undergo programmed cell death as a result of a significant increase of Bax and its translocation to the mitochondria.

Efecto apoptotico in vivo del interferon alfa-2b (IFN) sobre higados preneoplasicos de rata. / [In vivo apoptotic effect of alpha-2b interferon (IFN) on rat preneoplastic liver ]

In order to know whether IFN alpha prevents in vivo oncogenesis in the very-early-stage cancer cells, we evaluated the action of IFN alpha-2b on preneoplastic foci in rats. Animals were divided into six groups: subjected to an initiation-promotion model of cancer development (G1), treated with IFN alpha-2b during: a) initiation-promotion (G2), b) initiation (G3), promotion (G4); subjected only to an initiation stage (G5) and treated with IFN alpha-2b during this period (G6). The number and area of rGST P-positive foci were reduced and the Apoptotic index was increased in G2, 3 and 6. Bcl-2 and Bcl-XL protein levels were decreased in IFN alpha-2b-treated rats. Increased levels of mitochondrial Bax protein were observed in G2, 3 and 6. In conclusion, preneoplastic hepatocytes in the IFN alpha-2b-treated rats undergo programmed cell death as a result of a significant increase of Bax and its translocation to the mitochondria.