1022-7954/03/3907- $25.00 © 2003
Russian Journal of Genetics, Vol. 39, No. 7, 2003, pp. 748–755. Translated from Genetika, Vol. 39, No. 7, 2003, pp. 900–908.
Original Russian Text Copyright © 2003 by Grigorian, Lukanidin.
has been ﬁrst isolated as a gene specif-
ically expressed in murine and human metastatic tumor
cells . Expression of
in nonmetastatic murine
and human cell lines results in the phenotype alteration
and the appearance of a malignant tumor . Mts1 is a
11-kDa protein belonging to the S100 family of Ca
binding proteins. The S100 proteins are known to be
involved in a variety of cellular processes, like regula-
tion of cell growth and metabolism, cell–cell communi-
cations, cell motility, and cytoskeletal structure. These
proteins also participate in intracellular signaling and
cell division . Mts1 regulates cytoskeletal structure
and cell motility via interaction with actin and tro-
pomyosin [4, 5]. Our previous study has shown that
Mts1 could also interact with the heavy chain of non-
muscle myosin II (MHC) . This Mts1–MHC interac-
tion results in the inhibition of the MHC phosphoryla-
tion, alteration of cell motility, and, ultimately, in the
modiﬁcation of the tumor cell metastatic potential .
The tumor suppressor p53 protein is a transcrip-
tional factor that regulates a number of cellular pro-
cesses limiting tumorigenic transformation. In response
to different factors, like DNA damage, oncogene acti-
vation, oxidative stress, etc., cells under the action of
p53 can be either arrested at the S-phase of the cell
cycle, or switch to apoptosis, or start differentiation .
Molecular mechanisms underlying these processes and
the role of p53 in them are not fully understood.
As a transcription factor, p53 regulates the expres-
sion of target genes by binding to speciﬁc sequences of
these genes. The majority of the genes regulated by p53
are involved in the control of the cell cycle or apoptosis.
The p53 protein contains three main structural
domains. The N-terminal domain interacts with differ-
ent components of basal transcription machinery and
provides transcriptional regulation . The central part
of the protein is responsible for speciﬁc binding to
DNA. This protein region is a hot spot for p53 muta-
tions that affect the DNA binding ability thus promot-
ing tumorigenetic transformation of the cells. The C-
terminal part of p53 is a multifunctional domain. It is
responsible for protein oligomerization, transportation
into the nucleus, and binding to damaged DNA. In
addition, the C-terminal peptide regulates conforma-
tional transformation of the protein from active into
inactive form, thereby regulating the protein transcrip-
tional activity [10, 11].
In the present study we have shown that Mts1 binds
to the C-terminal domain of p53. This interaction
affects in vivo transcription of the p53 target genes.
Apoptosis induced by the interaction between these
two proteins depends on the cell line type.
MATERIALS AND METHODS
The pSV-mts1 construct was obtained by
cloning the coding region of
into pKS3 (Amer-
sham Pharmacia Biotech) vector; pSVBc12 was con-
structed by cloning the Bc12/
I insert from PEBS7-425
(kindly provided by M. Jaattela) into the pSK3 vector.
Murine p53 gene and its fragments were obtained by
use of PCR and cloned into the pQE30 (Qiagen,
GmbH, Hilden, Germany). For cloning into tet-induc-
ible expression system,
cDNA was cloned into
pUHD 10-3 vector and used for transfection of the cell
lines producing tetracycline-controlled transactivator
pUHD172neo (Clontech Laboratories, GmbH, Heidel-
berg, Germany). Plasmid p21-
was constructed by
cloning the p53-binding element from the p21/WAF pro-
moter into pfLuc plasmid containing the luciferase gene.
Cell line transfection.
Cells were transfected by
cells in 100
l of phosphate
Metastasis-Inducing Mts1/S100A4 Protein Binds
to Tumor Suppressor p53 Protein
M. Grigorian and E. Lukanidin
Institute of Cancer Biology, Danish Cancer Society, Copenhagen, Denmark; e-mail: firstname.lastname@example.org
Received October 22, 2002
—This study for the ﬁrst time demonstrates a physical and functional interaction between the Ca
binding protein Mts1/S100A4 and tumor suppressor p53 protein. Using different in vitro and in vivo
approaches, we have found that Mts1 can bind to the C-terminal regulatory domain of p53. The Mts1 binding
to p53 promotes activation of the reporter gene transcription in vivo. A modulation of the p53 target gene
) expression was observed upon Mts1 induction in the cells
expressing the wild-type p53. These results suggest that the ability of Mts1 to enhance p53-dependent apoptosis
of tumor cells leads to the decrease/disappearance of the tumor cells expressing the wild-type p53. Thus, Mts1
promotes selection of more aggressive, metastatic phenotype during tumor progression.