cDNA microarrays detect activation of a myogenic transcription program by the PAX3-FKHR fusion oncogene

Abstract

Alveolar rhabdomyosarcoma is an aggressive pediatric cancer of striated muscle characterized in 60% of cases by a t(2;13)(q35;q14). This results in the fusion of PAX3, a developmental transcription factor required for limb myogenesis, with FKHR, a member of the forkhead family of transcription factors. The resultant PAX3-FKHR gene possesses transforming properties; however, the effects of this chimeric oncogene on gene expression are largely unknown. To investigate the actions of these transcription factors, both Pax3 and PAX3-FKHR were introduced into NIH 3T3 cells, and the resultant gene expression changes were analyzed with a murine cDNA microarray containing 2,225 elements. We found that PAX3-FKHR but not PAX3 activated a myogenic transcription program including the induction of transcription factors MyoD, Myogenin, Six1, and Slug as well as a battery of genes involved in several aspects of muscle function. Notable among this group were the growth factor gene Igf2 and its binding protein Igfbp5. Relevance of this model was suggested by verification that three of these genes (IGFBP5, HSIX1, and Slug) were also expressed in alveolar rhabdomyosarcoma cell lines. This study utilizes cDNA microarrays to elucidate the pattern of gene expression induced by an oncogenic transcription factor and demonstrates the profound myogenic properties of PAX3-FKHR in NIH 3T3 cells.

SLUG in cancer development

“…SLUG expression is being increasingly recognized as an alteration in mesenchymal tumours (both leukaemias and sarcomas) (Inukai et al, 1999;Khan et al, 1999, and this paper), suggesting that SLUG may be a critical factor in tumour invasion not only of BCR-ABL-positive leukaemias but also potentially in other mesenchymal cancers. To show whether SLUG is required for BCR-ABL leukaemogenesis, we demonstrate that the leukaemogenic capacity of BCR-ABLp190 oncogene is dependent on the presence of Slug, indicating that Slug has a fundamental role in the biology of BCR-ABL cancer cells.…”

“…Slug is a member of the Snail family of zinc-finger transcription factors that share an evolutionarily conserved role in mesoderm formation in invertebrates and vertebrates (Nieto, 1994(Nieto, , 2002Sefton et al, 1998), In human and mouse, much of the knowledge regarding the function of SLUG has been derived from analysis of loss-of-function mutations (Jiang et al, 1998;PerezLosada et al, 2002;Sanchez-Martin et al, 2002, which have demonstrated that SLUG is critical for development of neural crest-derived cell lineages and from insights into the interaction of SLUG with specific oncogenes in human cancer, notably BCR-ABL (Inukai et al, 1999;Khan et al, 1999, and this manuscript). However, little is known as to how overexpression of SLUG might contribute to malignancy.…”

“…However, little is known as to how overexpression of SLUG might contribute to malignancy. We have utilized the single-plasmid system containing the regulating and expression elements of the original binary tetracycline system to allow high induction and tight control of gene expression by tetracycline in mice (Schultze et al, 1996) to try to understand the relevance of SLUG to human cancer development (Inukai et al, 1999;Khan et al, 1999, this manuscript). In the mouse Slug is not implicated in EMT (Sefton et al, 1998;Nieto, 2002), while the Snail gene has been shown to trigger EMT, an important pathway to acquisition of the invasive phenotype in epithelial solid tumours (Cano et al, 2000;Batlle et al, 2000).…”

“…SLUG expression is found in t(17;19) leukaemic cells (Inukai et al, 1999) rhabdomyosarcoma cells expressing the translocation PAX3-FKHR (Khan et al, 1999), and in breast cancer, where it is strongly correlated with loss of E-cadherin (Hajra et al, 2002). These previous observations of aberrant SLUG expression in human cancer cells (Inukai et al, 1999;Khan et al, 1999;Hajra et al, 2002) lead us to investigate the role of SLUG overexpression in malignancy by generating and analysing Slug-overexpressing mice. These mice did not exhibit morphological defects at birth, but did develop mesenchymal cancers similar to those associated with SLUG expression in humans.…”

The radioresistance biological function of the SCF/kit signaling pathway is mediated by the zinc-finger transcription factor Slug

“…Thus, constitutive activation of c-kit could confer radioresistance properties to the tumor cells. Moreover, recent findings show that Slug is also expressed in t(17;19) leukemic cells (Inukai et al, 1999), in rhabdomyosarcoma cells expressing the translocation PAX3-FKHR (Khan et al, 1999), and in cells expressing BCR-ABL (JPL et al, unpublished observations). Thus, Slug may be a common component providing radioresistance to tumor cells.…”