Clinical and experimental data indicate that hyaluronan accumulates in breast cancer compared with normal breast epithelium, which correlates to poor prognosis. In this review, we discuss the expression of genes encoding enzymes that synthesize or degrade hyaluronan, i.e. hyaluronan synthases and hyaluronidases or bind hyaluronan, i.e. CD44 and receptor for hyaluronan-mediated motility (RHAMM, also designated as HMMR or CD168), in relation to breast cancer progression. Hyaluronan and hyaluronan receptors have multi-faceted roles in signalling events in breast cancer. A better understanding of the molecular mechanisms underlying these signalling pathways is highly warranted and may lead to improvement of cancer treatment.

No abstract

The composition of the airway surface liquid, a thin layer of fluid covering the airway wall, has been debated. Two new techniques to determine the ionic composition of the airway surface liquid are presented. In the first technique, pieces of the airway were shock-frozen and analyzed by X-ray microanalysis in the frozen state in the scanning electron microscope. In the second technique, the airway surface liquid was collected with the help of dextran beads that were allowed to absorb the fluid. The beads were collected in silicon oil, cleaned, dried, and analyzed. Airway surface liquid from pig airways was isotonic to lightly hypertonic, whereas airway surface liquid from mouse and rat airways was hypotonic. The ionic composition of airway surface liquid from rodent airways could be changed by pharmacological stimulation of fluid transport. Transgenic mice with cystic fibrosis (CF) had significantly higher Na and Cl concentrations in the airway surface liquid than normal mice. Nasal fluid was also collected from humans. In CF patients, CF heterozygotes, and rhinitis patients, the levels of Na and Cl in the nasal fluid were signifi- cantly higher than in healthy controls. In CF patients K levels were also significantly higher than in healthy controls. The ionic concentrations in fluid collected from patients with primary ciliary dyskinesia (PCD) were not different from normal. Females with CF had significantly higher concentrations of Na, Cl and K in their nasal fluid compared to male patients. The dextran bead technique was also used to determine the ionic composition of the apical fluid in cultures of respiratory epithelial cells from healthy controls and CF patients. In the healthy controls, the fluid was hypotonic. In the CF cell cultures, the apical fluid had a higher Na and Cl concentration than in the controls.