A142
Effects of beta-catenin, LEF-1, c-jun and PEA 3 on Osteopontin expression in Malignant Melanoma
Koh Han Hoo2, Frederick Charles Campbell1
1Centre for Cancer Reserch and Cell Biology, Belfast, UK, 2Regional Plastics and Maxillofacial Unit of Northern Ireland, Belfast, UK
Background
Malignant melanoma is one of the most aggressive cancers affecting man. Its incidence worldwide is increasing faster than any other cancer. Although early melanoma is curable y resection, in the presence of metastasis, treatment is frequently unsuccessful and confers a poor prognosis. Osteopontin (OPN) is a key molecular mediator of invasiveness in various cancers. In a clinical study of melanoma progression, OPN overexpression was associated with melanoma invasion. OPN is not typically activated by a gain function mutation during tumourgenesis. Instead, various responsive elements in its promoter regulate OPN expression.
Method
We test the effects of OPN overexpression and inhibition on the invasive properties of B16-F1 weakly metastatic murine melanoma cells by stable tranfection of an OPN and OPN-antisense construct. Using an OPN-luciferase construct, we test the effects of OPN transcriptional regulators (beta-catenin, LEF-1, c-jun and PEA 3) individually and in combination, on OPN-promoter activation. Using immunohistochemistry we assessed the expression of OPN and its transcriptional regulators in human archival melanoma samples against pathological prognostic factors.
Results
We have found that the OPN transcriptional regulators up-regulate OPN promoter activity and there is a stepwise increase in up-regulation when transfected in combination. Immunohistochemical analysis shows a strong correlation between OPN and PEA3, and also OPN and tumour thickness.
Conclusion
We have identified PEA3 as a significant regulator of OPN and which also directly correlates with tumour thickness in malignant melanoma.
