Mj. Zinda et al., AKT-1,-2, and-3 are expressed in both normal and tumor tissues of the lung, breast, prostate, and colon, CLIN CANC R, 7(8), 2001, pp. 2475-2479
Purpose: The AKT/PKB kinase controls many of the intracellular processes th
at are dysregulated. in human cancer, including the suppression of apoptosi
s and anoilkis and the induction of cell cycle progression. Three isoforms
of AKT have been identified: AKT-1, -2, and -3. Selective up-regulation of
AKT-3 RNA expression has been reported in hormone-independent breast and pr
ostate cancer cell lines suggesting that AKT-3 expression may be increased
with breast or prostate tumor progression. To determine whether AKT-3 RNA e
xpression is selectively up-regulated in human cancers and whether the patt
erns of AKT RNA expression may change with tumor development, we examined A
KT isoform expression by RT-PCR in human cancer cell lines, primary human c
ancers, and normal human tissues.
Experimental Design: AKT-1, -2, and -3 RNA expression was examined by RT-PC
R. Because up-regulated AKT-3 expression has been implicated in human breas
t and prostate cancer progression, we also examined AKT-3 expression levels
by semiquantitative RT-PCR using matched normal/tumor first-strand cDNA pa
irs from colon, breast, prostate, and lung cancers.
Results: Our data reveal that the overwhelming majority of both normal and
tumor tissues express all three of the AKT isoforms. Moreover, semiquantita
tive RT-PCR of matched normal/tumor pairs confirmed similar AKT-3 RNA expre
ssion levels in both normal and tumor tissue.
Conclusions: Our data show that both normal and tumor tissues express all t
hree of the AKT isoforms and indicate that tumorigenesis does not involve a
dramatic shift in the RNA expression patterns of the three AKT isoforms.