Neuroblastoma
Coloractal
cancer
Apoptosis.
2006 Mar 2; [Epub ahead of print] Acta Pharmacol Sin.
2006 Mar;27(3):353-9.
Increasing ornithine
decarboxylase activity is another way of prolactin preventing methotrexate-induced
apoptosis: Crosstalk between ODC and BCL-2.
Hsu
PC, Hour
TC, Liao YF, Hung
YC, Liu
CC, Chang
WH, Kao
MC, Tsay GJ, Hung
HC, Liu
GY.
Department of Medicine, Da-Chien General
Hospital, Miao-Li, Taiwan, R.O.C..
Prolactin has more than 300 separate functions
including affecting mammary growth, differentiation, secretion and
anti-apoptosis. In the previous studies, prolactin
induced Bcl-2 expression to prevent apoptosis and also provoked the
activity of ornithine decarboxylase
(ODC). Our previous data showed that ODC overexpression
upregulates Bcl-2 and prevents tumor necrosis
factor alpha (TNF-alpha)- and methotrexate
(MTX)-induced apoptosis. Here, we further investigate whether prolactin prevents MTX-induced apoptosis through
inducing ODC activity and the relationship between ODC and Bcl-2 upon prolactin stimulation. Prolactin
prevented MTX-induced apoptosis in a dose-dependent manner in HL-60 cells.
Following prolactin stimulation, ODC enzyme
activity also shows an increase in a dose-dependent manner, expressing its
maximum level at 3 h, and rapidly declining thereafter. Prolactin-induced
ODC activity is completely blocked by a protein kinase
C delta (PKCdelta) inhibitor, rottlerin.
However, there are no changes in the expressions of ODC mRNA and protein
level after prolactin stimulus. It indicates that
prolactin may induce ODC activity through the PCKdelta pathway. Besides, Bcl-2 expresses within 1 h
of prolactin treatment and this initiating effect
of prolactin is not inhibited by alpha-difluoromethylornithine (DFMO). However, Bcl-2 is
further enhanced following prolactin stimulation
for 4 h and this enhancement is blocked by DFMO. Bcl-2 has no effect on ODC
activity and protein levels, but ODC upregulates
Bcl-2, which is inhibited by DFMO. Overall, there are two different forms
of prolactin effect, it induces Bcl-2 primarily,
and following this it stimulates ODC activity. Consequently induced ODC
activity further enhances the expression of Bcl-2. The anti-apoptotic
effect of prolactin is diminished by DFMO and
recovered by putrescine. Obviously, ODC activity
is one basis for the anti-apoptotic mechanisms of prolactin.
A Bcl-2 inhibitor, HA14-1, together with DFMO, completely blocks the
anti-apoptotic effects of prolactin. These
results suggest that increasing ODC activity is another way of prolactin preventing MTX-induced apoptosis and that
this induction of ODC activity enhances the expression of Bcl-2 strongly
enough to bring about the anti-apoptotic function.
PMID: 16520895 [PubMed - as supplied by publisher]
Adenovirus-mediated expression of both antisense ODC and AdoMetDC
inhibited colorectal cancer cell growth in vitro.
Zhang
B, Liu
XX, Zhang
Y, Jiang CY, Teng QS, Hu HY, Wang
W, Gong
L.
AIM: To construct a recombinant adenovirus that can simultaneously express
both antisense ornithine
decarboxylase (ODC) and adenosylmethionine
decarboxylase ( AdoMetDC ) and detect its inhibitory effect on
the intracellular polyamine pool and colorectal cancer cell growth. METHODS:
A 205-bp cDNA of AdoMetDC
was reverse-inserted into recombinant pAdTrack-ODCas
vectors and recombined with pAdEasy-1 vectors in AdEasy-1 cells. Positive
clones were selected and transfected into the
packaging cell HEK293 after they were linearized
by PacI. Green fluorescent protein expression was
used to monitor the process of adenovirus packaging. The ODC and AdoMetDC protein levels were identified by western
blotting, and intracellular polyamine content was detected by reverse-phase
high performance liquid chromatography. A viable cell count was used to
determine the growth of HT-29 cells with or without exogenous polyamine.
RESULTS: Sequencing confirmed that AdoMetDC cDNA was successfully ligated
into the pAdTrack-ODCas vector. GFP expression in
293 cells during virus packing and amplification was observed by
fluorescence microscopy. Western blotting demonstrated that both ODC and AdoMetDC were downregulated
by Ad-ODC-AdoMetDCas, and consequently 3 kinds of
polyamine (putrescine, spermidine
and spermine) were reduced to very low levels.
HT-29 cell growth was significantly inhibited as compared with control
conditions, and growth arrest was not reversed by exogenous putrescine. CONCLUSION: The successfully constructed
recombinant adenovirus, Ad-ODC-AdoMetDCas,
blocked polyamine synthesis and has therapeutic potential for treating
colorectal cancer in vitro.
PMID: 16490173 [PubMed - in process]