High expression of Wee1 is associated with poor disease-free survival in malignant melanoma: potential for targeted therapy.
Notoriously resistant malignant melanoma is one of the most increasing forms of cancer worldwide; there is thus a precarious need for new treatment options. The Wee1 kinase is a major regulator of the G(2)/M checkpoint, and halts the cell cycle by adding a negative phosphorylation on CDK1 (Tyr15). Additionally, Wee1 has a function in safeguarding the genome integrity during DNA synthesis. To assess the role of Wee1 in development and progression of malignant melanoma we examined its expression in a panel of paraffin-embedded patient derived tissue of benign nevi and primary- and metastatic melanomas, as well as in agarose-embedded cultured melanocytes. We found that Wee1 expression increased in the direction of malignancy, and showed a strong, positive correlation with known biomarkers involved in cell cycle regulation: Cyclin A (p<0.0001), Ki67 (p<0.0001), Cyclin D3 (p = 0.001), p21(Cip1/WAF1) (p = 0.003), p53 (p = 0.025). Furthermore, high Wee1 expression was associated with thicker primary tumors (p = 0.001), ulceration (p = 0.005) and poor disease-free survival (p = 0.008). Transfections using siWee1 in metastatic melanoma cell lines; WM239(WTp53), WM45.1(MUTp53) and LOX(WTp53), further support our hypothesis of a tumor promoting role of Wee1 in melanomas. Whereas no effect was observed in LOX cells, transfection with siWee1 led to accumulation of cells in G(1)/S and S phase of the cell cycle in WM239 and WM45.1 cells, respectively. Both latter cell lines displayed DNA damage and induction of apoptosis, in the absence of Wee1, indicating that the effect of silencing Wee1 may not be solely dependent of the p53 status of the cells. Together these results reveal the importance of Wee1 as a prognostic biomarker in melanomas, and indicate a potential role for targeted therapy, alone or in combination with other agents.
Department of Pathology, The Norwegian Radium Hospital, Oslo, Norway.
Gry Irene
GI
Magnussen
Ruth
R
Holm
Elisabeth
E
Emilsen
Anne Katrine Ree
AK
Rosnes
Ana
A
Slipicevic
Vivi Ann
VA
Flørenes
D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics*; D049109:Cell Proliferation; D018572:Disease-Free Survival; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000473:pathology* / Q000628:therapy; D009687:Nuclear Proteins / Q000235:genetics*; D011379:Prognosis; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D034741:RNA, Small Interfering
D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D011505:Protein-Tyrosine Kinases; C499349:WEE1 protein, human