Gc. Owens et al., OVEREXPRESSION OF A TRANSMEMBRANE ISOFORM OF NEURAL CELL-ADHESION MOLECULE ALTERS THE INVASIVENESS OF RAT CNS-1 GLIOMA, Cancer research, 58(9), 1998, pp. 2020-2028
CNS-1 is a highly invasive neural cell adhesion molecule (NCAM)-positi
ve rat glioma that exhibits similarities in its pattern of infiltratio
n to human gliomas, To investigate whether increasing NCAM expression
alters invasive behavior, retroviruses encoding human NCAM 140 and a c
ytoplasmic truncation of NCAM 140 were used to transduce a population
of CNS-1 glioma cells that had a relatively low endogenous level of NC
AM. Compared to cells transduced with a control virus, cells overexpre
ssing either intact or truncated human NCAM 140 showed decreased invas
ion of a reconstituted basal lamina, Changes in growth rate or in key
matrix metalloproteinase activities could not account for this result.
In a migration assay on type IV collagen, cells exhibited a substrate
concentration-dependent increase in the rate of migration; however, o
verexpression of NCAM 140 or truncated NCAM 140 inhibited motility at
higher substrate concentrations. Consistent with these findings was th
e decreased spread of NCAM 140 overexpressers in vivo following instil
lation of cells into the right frontal cortex of rat brain. NCAM 140 o
verexpressers showed considerably more restricted perivascular and per
iventricular spread than cells transduced with a control virus, Howeve
r, NCAM-140-overexpressing tumor exhibited a less cohesive pattern of
growth near the site of tumor instillation and more individual cell in
filtration of brain parenchyma with more pronounced perineuronal satel
litosis. The stability of recombinant NCAM expression was confirmed by
recovering tumor cells from tumor-bearing animals and measuring NCAM
levels by flow cytometry. These observations show that overexpression
of NCAM 140 decreases the long-range spread of CNS-1 glioma along basa
l lamina pathways but enhances local infiltration of neuropil.