GROWTH AS A SOLID TUMOR OR REDUCED GLUCOSE-CONCENTRATIONS IN CULTURE REVERSIBLY INDUCE CD44-MEDIATED HYALURONAN RECOGNITION BY CHINESE-HAMSTER OVARY CELLS
Z. Zheng et al., GROWTH AS A SOLID TUMOR OR REDUCED GLUCOSE-CONCENTRATIONS IN CULTURE REVERSIBLY INDUCE CD44-MEDIATED HYALURONAN RECOGNITION BY CHINESE-HAMSTER OVARY CELLS, The Journal of clinical investigation, 100(5), 1997, pp. 1217-1229
The density, molecular isoform, and posttranslational modifications of
CD44 can markedly influence growth and metastatic behavior of tumors.
Many CD44 functions, including some involving tumors, have been attri
buted to its ability to recognize hyaluronan (HA). However, only certa
in CD44-bearing cells bind soluble or immobilized HA. We now show that
CD44 made by wild-type Chinese hamster ovary (CHO-KI) cells and a lig
and-binding subclone differ with respect to N-linked glycosylation. Wh
ile both bear CD44 with highly branched, complex-type glycoforms, CD44
expressed by the wad type was more extensively sialylated, CHO-KI cel
ls which failed to recognize HA when grown in culture gained this abil
ity when grown as a solid tumor and reverted to a non-HA-binding state
when returned to culture, The ability of CHO-K1 cells to recognize HA
was also reversibly induced when glucose concentrations in the medium
were reduced. Glucose restriction influenced CD44-mediated HA binding
by many but not ail, of a series of murine tumors. Glucose concentrat
ions and glycosylation inhibitors only partially influenced CD44 recep
tor function on resting murine B lymphocytes. These observations sugge
st that glucose levels or other local environmental conditions may mar
kedly influence glycosylation pathways used by some tumor cells, resul
ting in dramatic alteration of CD44-mediated functions.