Altered expression of CKs 14/20 is an early event in a rat model of multistep bladder carcinogenesis.

Cytokeratins (CKs) 14 and 20 are promising markers for diagnosing urothelial lesions and for studying their prognosis and histogenesis. This work aimed to study the immunohistochemical staining patterns of CK14/20 during multistep carcinogenesis leading to papillary bladder cancer in a rat model. Thirty female Fischer 344 rats were divided into three groups: group 1 (control); group 2, which received N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 20 weeks plus 1 week without treatment; and group 3, which received BBN for 20 weeks plus 8 weeks without treatment. Bladder lesions were classified histologically. CK14 and CK20 immunostaining was assessed according to its distribution and intensity. In control animals, 0-25% of basal cells and umbrella cells stained positive for CK14 and CK20 respectively. On groups 2 and 3, nodular hyperplastic lesions showed normal CK20 and moderately increased CK14 staining (26-50% of cells). Dysplasia, squamous metaplasia, papilloma, papillary tumours of low malignant potential and low- and high-grade papillary carcinomas showed increased CK14 and CK20 immunostaining in all epithelial layers. Altered CK14 and CK20 expression is an early event in urothelial carcinogenesis and is present in a wide spectrum of urothelial superficial neoplastic and preneoplastic lesions.

DNA content analysis, expression of Ki-67 and p53 in rat urothelial lesions induced by N-butyl-N-(4-hydroxybutyl) nitrosamine and treated with mitomycin C and bacillus Calmette-Guérin.

N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-induced urothelial carcinogenesis is a useful model for studying urothelial carcinogenesis. Here, the DNA content and the expression of Ki-67 and p53 in urothelial lesions induced by BBN and treated with mitomycin C (MMC) and Bacillus Calmette-Guérin (BCG) were investigated. Female Fisher 344 rats were distributed into five groups treated with 0.05% BBN in their drinking water for 20 weeks. Ten animals were used as negative control. Intravesical instillations were performed with MMC, BCG and physiological saline solution (PSS), once per week, for 6 weeks. The animals were sacrificed 1 week after the last intravesical instillation. DNA ploidy analysis was carried out by static cytometry. Ki-67 and p53 were analysed immunohistochemically in paraffin-embedded tissue. The incidence of lesions developed in rats with PSS was greater than in rats instilled with MMC and BCG. The incidence of aneuploidy was lower in tumours treated with MMC and BCG. Low- and high-grade papillary carcinoma treated with MMC and BCG showed a decrease in labelling index and an increase of apoptotic index. The proliferative index was correlated with the apoptotic index (r=0.438, p<0.01). Significant correlations were also found between the proliferative index and lesion, and the apoptotic index and lesion (r=0.425, p<0.01 and r=0.275, p<0.01), respectively. A significant correlation was found between ploidy and the apoptotic index (r=0.245, p<0.05). Our results provide information on the biological behaviour of chemically-induced bladder tumours treated with MMC and BCG.

Vascular wall: potential target for the physicochemical effects of cis-unsaturated free fatty acids.

Diets rich in monounsaturated cis-FFA (cis FFA) are associated with a significant reduction of cardiovascular risk. Although several different mechanisms have been proposed to explain this protective effect, the biochemical processes involved have not been fully elucidated. It has been shown that upon their incorporation into the plasma membrane, cis FFA induce a marked perturbation of the lipid domains, altering membrane fluidity as well as lipid-lipid and lipid-protein interactions in the bilayer plane. During the last few years, several lines of evidence have shown that these perturbations disrupt the activity of several membrane proteins and enzymatic systems. As a result, several critical transmembrane signaling systems, including the Ins(1,4,5)P(3)/DAG/[Ca(2+)](i), the cAMP/PKA, and the voltage-operated Ca(2+) influx are strongly inhibited by cis FFA in different experimental models. Furthermore, this inhibition is associated with alterations in the timing of the cell cycle as well as in the final steps of the secretory pathway. We propose that this complex set of biological actions exerted by cis FFA at the plasma membrane may contribute to explain the protective roles that these molecules appear to exert on the vascular wall.