Possible Role of Calponin h1 as a Tumor Suppressor in Human Uterine Leiomyosarcoma

• Published in: JNCI : Journal of the National Cancer Institute 1999-05, Vol.91 (9), p.790-796
• Main Authors: Horiuchi, Akiko, Nikaido, Toshio, Taniguchi, Shunichiro, Fujii, Shingo
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Blotting, Southern; Blotting, Western; Calcium-Binding Proteins - genetics; Calcium-Binding Proteins - metabolism; Calponins; Cancer; Cell Division; DNA, Complementary - metabolism; Female; Female genital diseases; Gynecology. Andrology. Obstetrics; Humans; Immunohistochemistry; In Vitro Techniques; Leiomyosarcoma - metabolism; Leiomyosarcoma - pathology; Medical research; Medical sciences; Mice; Mice, Nude; Microfilament Proteins; Muscle Proteins - genetics; Muscle Proteins - metabolism; Proteins; Reverse Transcriptase Polymerase Chain Reaction; Transfection; Tumors; Uterine Neoplasms - metabolism; Uterine Neoplasms - pathology
• ISSN: 0027-8874; 1460-2105
• DOI: 10.1093/jnci/91.9.790

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.