Expression of the smooth muscle calponin gene in human osteosarcoma and its possible association with prognosis

Abstract

The basic calponin gene is a smooth muscle differentiation‐specific gene that encodes an actin‐binding protein involved in the regulation of smooth muscle contractility. We studied the expression of the calponin gene in 8 human osteosarcoma cell lines and 17 primary human osteosarcoma tissues by RT‐PCR analysis. We also analyzed mRNA expression of smooth muscle‐specific genes including SM22α, caldesmon and α‐actin, and for neutral and acidic calponin isoforms. The genes were expressed at various levels by osteosarcoma cell lines and tissues of diverse histological subtypes. The basic calponin protein of an expected size was detected in osteosarcoma cell lines by immunoblot analysis and was localized by immunohistochemistry in the cytoplasm of the tumor cells in osteosarcoma tissues. Survival was found to be significantly increased in patients whose tumors exhibited basic calponin expression, compared with those with no expression. Alterations in the expression of other markers examined were not correlated with prognosis. Our results suggest that the basic calponin gene product may be a novel prognostic variable in patients with osteosarcoma. Int. J. Cancer (Pred. Oncol.) 79:245–250, 1998.© 1998 Wiley‐Liss, Inc.

Developmentally regulated expression of calponin isoforms and the effect of h2-calponin on cell proliferation

“…Also, h1-calponin knockout mice displayed enhanced ectopic bone formation when they were stimulated by recombinant human bone morphogenetic protein-2, once again suggesting calponin's function as a suppressor of cell proliferation. Calponin has been detected in the cytoplasm of human osteosarcoma cells, and the survival rate of patients whose tumors exhibit calponin is significantly higher than that of those whose tumors do not express calponin (50). Consistently, the h1-calponin knockout mice also had an early onset of cartilage formation and ossification and accelerated healing of bone fractures (51).…”

Differential Expression of Splicing Variants of the Human Caldesmon Gene (CALD1) in Glioma Neovascularization versus Normal Brain Microvasculature

“…The resulting cDNA was amplified by PCR using CALD1 specific primer sets spanning the splice sites of this gene toward all of the four splicing variants of l-CaD as described elsewhere. 7 A primer set for the CALD1, designed to amplify all of the splicing variants, 25 was used for initial examining the microdissected samples (the product size for l-CaD isoforms is 744 bp). Glyceraldehyde 3-phosphate dehydrogenase (GAPD) fragment 26 was prepared by PCR as an internal control.…”

Mice lacking smooth muscle calponin display increased bone formation that is associated with enhancement of bone morphogenetic protein responses

“…The effect of this mutation on the contractile function of smooth muscle is reported elsewhere . Since basic calponin is expressed at various levels in human osteoblast cell lines and osteosarcoma tissues (Yamamura et al 1998), we examined whether the endogenous murine basic calponin is expressed in bone tissues. Reverse transcription-PCR (RT-PCR) analysis using total RNA prepared from the calvaria bone tissue of wild-type mice demonstrated that the endogenous basic calponin messenger RNA (mRNA) was highly expressed in embryos, expressed at low levels until 7 weeks after birth, and was not at all detectable in 12-week-old mice ( Fig.…”