Differential Expression of CCN1/CYR61, CCN3/NOV, CCN4/WISP1, and CCN5/WISP2 in Neurofibromatosis Type 1 Tumorigenesis

The hallmark of neurofibromatosis type 1 is the development of dermal and plexiform neurofibromas. Neurofibromatosis type 1 patients with plexiform neurofibromas are at risk of developing malignant peripheral nerve sheath tumors. We applied a 22,000-oligonucleotide microarray transcriptomic approach to a series of plexiform neurofibromas in comparison with dermal neurofibro-mas, and results were confirmed with real-time quantitative reverse transcription-polymerase chain reaction. Thirteen genes were up-regulated and 10 were downregulated in plexiform neurofibromas. The upregulated genes mainly encode molecules involved in cell adhesion, extracellular matrix, fibrogenesis, and angiogenesis. Several CCN gene family members were dysregulated in neuro-fibromatosis type 1 tumorigenesis; the angiogenic gene CCN1/CYR61 was specifically upregulated in the plexiform neurofibromas; CCN4/WISP1 was upregulated, and CCN3/NOV and CCN5/WISP2 were downregulated in paired comparisons of plexiform neuro-fibroma and malignant peripheral nerve sheath tumor from the same patients. CCN1 and CCN3 proteins were detected by immuno-histochemistry in neurofibromatosis type 1-associated tumors. Up-regulation of S100A8 , S100A9 , and CD36 was also observed and suggests a role of this pathway in inflammation-associated genesis of plexiform neurofibromas. In summary, a limited number of pathways are potentially involved in plexiform neurofibroma development. Some of the genes identified, particularly CCN1 , might be useful diagnostic or prognostic markers or form the basis for novel therapeutic strategies.