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Isolation of genes differentially expressed in human primary myoblasts and embryonal rhabdomyosarcoma
M Genini1, P Schwalbe, F A Scholl
1Department of Pediactrics, Division of Clinical Chemistry, University of Zurich, Switzerland.
Abstract:
Using a subtractive hybridization method, we have cloned 48 cDNAs which are expressed in human primary myoblasts but down-regulated in the embryonal-rhabdomyosarcoma (RMS) cell line RD. Twenty-nine sequences could be identified as coding for previously known gene products, while 19 encode unknown proteins. Twelve clones coding for known proteins that were highly down-regulated in the RD cells were chosen for further analysis on Northern blots containing additional normal and RMS cells. The expression pattern of TGF-beta-induced gene product-3 (beta(ig)H3), inhibitory G-protein alpha sub-unit (G(alpha)i2), osteoblast-specific factor-2 (OSF-2), 22-kDa smooth-muscle protein (SM22), clone A3351 (homologous to mouse talin), testican, thrombospondin-1 and thrombospondin-2 suggests involvement of these proteins in the genesis of the neoplastic phenotype. Among the clones with unknown sequence, several are identical or homologous to expressed sequence tags or known cDNAs, such as integrins or laminin. These results suggest that several isolated clones might have an important role in the determination or maintenance of the normal phenotype, and thus their loss is possibly involved in the progression of malignancy.
Insights
Researchers identified 48 cDNAs in human muscle cells, with 19 showing reduced expression in rhabdomyosarcoma. These findings suggest key proteins involved in muscle cell function may be lost during cancer development.
Area of Science:
- Molecular Biology
- Oncology
- Cell Biology
Background:
- Human primary myoblasts serve as a baseline for normal muscle cell function.
- Embryonal rhabdomyosarcoma (RMS) is a pediatric cancer with poorly understood molecular underpinnings.
- Gene expression differences between normal and cancerous cells can reveal critical pathways in tumorigenesis.
Purpose of the Study:
- To identify genes expressed in normal human myoblasts but downregulated in the RD RMS cell line.
- To investigate the potential role of these downregulated genes in the development and maintenance of the normal muscle phenotype.
- To explore the implications of gene loss in the progression of rhabdomyosarcoma.
Main Methods:
- Subtractive hybridization was employed to isolate differentially expressed cDNAs.
- Northern blot analysis was used to validate expression patterns in various normal and RMS cell lines.
- Sequence identification and homology searches were performed for cloned cDNAs.
Main Results:
- 48 cDNAs were cloned, with 29 identified as known gene products and 19 as unknown proteins.
- Downregulation of specific known genes, including beta(ig)H3, G(alpha)i2, OSF-2, SM22, talin, testican, thrombospondin-1, and thrombospondin-2, was confirmed in RD cells.
- Several novel clones showed homology to known genes involved in cell adhesion and structure, such as integrins and laminin.
Conclusions:
- The identified downregulated genes, including those encoding beta(ig)H3 and thrombospondins, may play crucial roles in maintaining the normal muscle cell phenotype.
- The loss or downregulation of these genes in RMS suggests their involvement in the neoplastic transformation and malignant progression.
- Further investigation into these candidate genes could reveal novel therapeutic targets for rhabdomyosarcoma.