VON-HIPPEL-LINDAU GENE-MEDIATED GROWTH SUPPRESSION AND INDUCTION OF DIFFERENTIATION IN RENAL-CELL CARCINOMA-CELLS GROWN AS MULTICELLULAR TUMOR SPHEROIDS
B. Lieubeauteillet et al., VON-HIPPEL-LINDAU GENE-MEDIATED GROWTH SUPPRESSION AND INDUCTION OF DIFFERENTIATION IN RENAL-CELL CARCINOMA-CELLS GROWN AS MULTICELLULAR TUMOR SPHEROIDS, Cancer research, 58(21), 1998, pp. 4957-4962
Previous results using gene transfection methods have shown that the w
ild-type (WT) von Hippel-Liudau (VHL) gene can function as a potent tu
mor suppressor gene in vivo for renal cell carcinoma (RCC) cells in th
e absence of any suppressive effect on cell growth in monolayer cell c
ulture under serum-rich conditions. Because we had previously found th
at the function of some oncogenes, such as mutant ras, can be influenc
ed by three-dimensional growth as multicellular spheroids (J, Rak et a
l., J, Cell Biol,, 131: 1587-1598, 1995), we reasoned the same might b
e true for suppressor genes as well. We, therefore, decided to compare
and study the effects of the WT VHL gene in monolayer versus three-di
mensional culture systems of the RCC cell line 786-0, which contains a
n inactivated VHL gene. We found that the reintroduction of the WT VHL
gene into mutant VHL RCC cells resulted in growth suppression in vitr
o, but only when the cells were grown as spheroid cultures. This decre
ase in cell proliferation was associated with several features of cell
differentiation/morphogenesis, as shown by light and electron microsc
opy. Thus, in contrast to cultures of mutant VHL RCC cells, which form
ed very compact and cohesive spheroids, the WT VHL transfectants were
loosely arranged and formed a network of tubular and trabecular struct
ures within the spheroids. The morphological changes of the WT VHL sph
eroids were associated with the,deposition of fibronectin in the extra
cellular space, a feature that was absent in the mutant and inactivate
d VHL gene-expressing spheroids. The results suggest the VHL gene may
be involved in the maintenance of the epithelial phenotype of renal tu
bular cells, i.e., it may act as a differentiation/morphogenetic facto
r. Moreover, this effect in tumors cells appears to be highly dependen
t on multicellular growth conditions that mimic the basic nature of so
lid tumors, such as RCC.