Effect of syndecan-1 overexpression on mesenchymal tumour cell proliferation with focus on different functional domains.
OBJECTIVE
Syndecan-1 is a transmembrane proteoglycan involved in various biological processes. Its extracellular, transmembrane and cytoplasmic domains may all participate in signal transduction. The aim of this study was to investigate the biological roles of these domains of syndecan-1.


METHODS
We transfected cells of two mesenchymal tumour cell lines with a full-length syndecan-1 construct and three truncated variants, namely 78 construct lacking the EC domain with exception of DRKE sequence; 77 construct lacking extracellular the whole domain and RMKKK corresponding to a short cytoplasmic motif. Subcellular distribution was revealed using confocal laser microscopy. Overexpression of the constructs was verified using real-time RT-PCR and by FACS analysis and effects of syndecan-1 on cell behaviour were explored. Cell cycle analysis allowed for dissection of mechanisms regulating cell proliferation.


RESULTS
Overexpression of syndecan-1 influenced expression profile of the other syndecan members, and decreased tumour cell proliferation significantly by two mechanisms, as follows: increased length of G0/G1 phase was the most evident change in RMKKK and 77 transfectants, whereas prolonged S phase was more obvious in full-length transfectants. Overexpression of syndecan-1 changed the tumour cell morphology in an epithelioid direction.


CONCLUSIONS
Both full-length and truncated syndecan-1 inhibited proliferation of the mesenchymal tumour cells, providing new insights into the importance for cancer growth of different functional domains of this proteoglycan.
Department of Laboratory Medicine, Division of Pathology, Karolinska Institutet, Stockholm, Sweden. fang.zong@ki.se
F
F
Zong
E
E
Fthenou
J
J
Castro
B
B
Péterfia
I
I
Kovalszky
L
L
Szilák
G
G
Tzanakakis
K
K
Dobra
D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005354:Fibrosarcoma / Q000378:metabolism / Q000473:pathology; D005434:Flow Cytometry; D016193:G1 Phase; D006801:Humans; D008654:Mesothelioma / Q000378:metabolism / Q000473:pathology; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016192:Resting Phase, Cell Cycle; D053668:Syndecan-1 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D053669:Syndecan-2 / Q000235:genetics / Q000378:metabolism; D053670:Syndecan-3 / Q000235:genetics / Q000378:metabolism; D053671:Syndecan-4 / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D011993:Recombinant Fusion Proteins; D053668:Syndecan-1; D053670:Syndecan-3; D053671:Syndecan-4; D053669:Syndecan-2