B. Palazzotti et al., Increased growth capacity of cervical-carcinoma cells over-expressing manganous superoxide dismutase, INT J CANC, 82(1), 1999, pp. 145-150
Increases in the expression of manganese-dependent superoxide dismutase (Mn
SOD) have been detected in several classes of human and experimental tumors
and appear to correlate with poorer prognosis in human neuro-epithelial, o
varian and cervical tumors, To delineate the relevance of MnSOD expression
to tumor-cell growth and survival, a human MnSOD cDNA was over-expressed in
the HeLa cervical-carcinoma cell line. MnSOD over-expression had marginal
effects on the growth of HeLa cells in standard medium, but markedly protec
ted the cells from growth suppression and cell death in conditions of serum
deprivation, Serum starvation did not affect expression of endogenous MnSO
D in wild-type HeLa cells, but was associated with increases in cell death
and in the generation of intracellular oxygen radicals. By contrast, in HT2
9 colon-carcinoma cells, which are relatively resistant to growth-factor wi
thdrawal, serum deprivation was associated with increases in MnSOD expressi
on and activity. Together these observations suggest that MnSOD provides a
mechanism for counteracting the intracellular oxidative processes that impa
ir cell growth and viability in the context of growth-factor withdrawal and
, in this context, may promote tumor cell survival in vivo in conditions no
rmally unfavorable to cell growth. (C) 1999 Wiley-Liss, Inc.