The insulin-like growth factor-I receptor inhibitor picropodophyllin causes tumor regression and attenuates mechanisms involved in invasion of uveal melanoma cells.
OBJECTIVE
Uveal melanoma has a high mortality rate due to a high incidence of metastasis (up to 50%), which preferentially occurs in the liver. Conventional chemotherapy, being the only therapeutic option today against metastatic uveal melanoma, has not proved to be effective. Therefore, new molecular targets important for malignant phenotype of uveal melanoma have to be found to design efficient pharmacologic agents.


METHODS
We previously reported data indicating that the insulin-like growth factor-1 receptor (IGF-IR) is a metastasis predictor as well as a therapeutic target for uveal melanoma. In the present study, we made use of the cyclolignan picropodophyllin (PPP), which is an inhibitor of the IGF-IR.


RESULTS
We showed that PPP efficiently blocks growth and viability of uveal melanoma cells in cultures and causes tumor regression in xenografted mice. In addition, treatment with PPP inhibited several mechanisms involved in metastasis, including tumor cell adhesion to extracellular matrix proteins, activity and expression of matrix metalloproteinase 2, and cell migration as well as invasion through basement membranes and endothelial cell layers. Furthermore, PPP significantly delayed establishment of uveal melanoma tumors and drastically reduced the incidence of liver metastasis in mice.


CONCLUSIONS
Our data suggest that IGF-IR is crucial for growth and survival as well as invasion and metastasis of uveal melanoma cells. Targeting this receptor may therefore comprise a strategy to treat ongoing disease (today incurable) as well as a strategy to prevent development of metastases in patients with primary disease.
Cellular and Molecular Tumor Pathology, Department of Oncology and Pathology, Cancer Centre Karolinska R8:04, Karolinska Hospital, Stockholm, Sweden.
Ada
A
Girnita
Charlotta
C
All-Ericsson
Mario A
MA
Economou
Kristina
K
Aström
Magnus
M
Axelson
Stefan
S
Seregard
Olle
O
Larsson
Leonard
L
Girnita
D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008545:Melanoma / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D008546:Melanoma, Experimental / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D051379:Mice; D016513:Mice, SCID; D009361:Neoplasm Invasiveness; D010766:Phosphorylation / Q000187:drug effects; D011034:Podophyllotoxin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014604:Uveal Neoplasms / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D023041:Xenograft Model Antitumor Assays / Q000379:methods
C415032:picropodophyllin; D017526:Receptor, IGF Type 1; D011034:Podophyllotoxin