7: J Natl Cancer Inst 1999 May 5;91(9):790-6

Possible role of calponin h1 as a tumor suppressor in human uterine
leiomyosarcoma.

Horiuchi A, Nikaido T, Taniguchi S, Fujii S.

Department of Obstetrics and Gynecology, Shinshu University School of Medicine,
Asahi, Matsumoto, Japan.

BACKGROUND: Calponin h1, a basic actin-binding protein capable of inhibiting
smooth muscle contraction, is a constitutive element of smooth muscle cells.
However, in leiomyosarcoma (a type of smooth muscle neoplasm of the uterus),
reduced expression of calponin h1 is observed, as we have reported previously.
In this study, we sought to assess the effects (in vitro and in vivo) of
increasing calponin h1 expression in leiomyosarcoma cells. METHODS: A plasmid
containing a human calponin h1 complementary DNA and a bacterial
neomycin-resistance gene was transfected into the human leiomyosarcoma cell
lines SKN and SK-LMS-1 by electroporation. Southern blotting, reverse
transcription-polymerase chain reaction analysis, western blotting, and
immunohistochemistry were used to confirm DNA transfer and expression of the
calponin h1 protein in neomycin-resistant clones. We characterized the
morphology of calponin h1-transfected cells, and we evaluated their
proliferative activity and tumorigenicity by use of a
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay, an
anchorage-independent growth assay, and a nude mouse tumorigenicity assay.
RESULTS: The morphology of calponin h1-transfected cells in culture resembled
that of cultured normal myometrial smooth muscle cells. With SK-LMS-1 cells,
proliferation of calponin h1-transfection cells was reduced to 69% of control;
with SKN cells, calponin h1 transfection reduced proliferation to 70% of
control. In assays of anchorage-independent growth and in vivo tumorigenicity,
both growth and tumorigenicity were statistically significantly reduced in
calponin h1-transfected leiomyosarcoma cells. CONCLUSIONS: Calponin h1 may
function as a tumor suppressor in leiomyosarcoma. Clinically, transfer of a
calponin h1 complementary DNA into poorly differentiated leiomyosarcoma cells
may be of potential therapeutic value through induction of a normal,
differentiated cellular phenotype.

PMID: 10328110 [PubMed - indexed for MEDLINE]