Purpose
To evaluate the effects of a novel small molecule KCN1 in suppressing of ocular melanoma in vitro and in vivo.
Methods
Human uveal melanoma Mel270 and Mel290, and mouse melanoma B16F10, B16LS9 cell lines were cultured with KCN1 or DMSO. SRB cell cytotoxicity assay was performed. Total RNA was extracted and RT-PCR analysis was performed. The protein expression of p-met, p-MAPK, p-STAT3, MMP2, MMP9, CA9 and Bcl-2 was detected by Western Blot. The level of VEGF protein in the culture media was measured by ELISA. Melanoma cells were then transfected with reporter constructs driven by V6R, VEGF and CA9 promoters. 220 C57Bl/6 mice were inoculated into their right eyes with 5X105 B16LS9 melanoma cells, and randomly assigned into 22 groups (n=10). Timing and dosing experiments were performed using 30 mg/kg or 60mg/kg KCN1 i.p. starting on days 1, 4, or 7 after inoculation. Tumor-burden eyes were enucleated on the 7th day after inoculation for size measurement, and livers were collected on the 28th day for number count. A longitudinal experiment was also performed to determine the hepatic micrometastases and serum VEGF level at weeks 1, 2, 3, 4 and 5. Proliferation, apoptosis and angiogenesis markers were evaluated in the ocular melanoma by immunostaining.
Results
KCN1 inhibited melanoma cell growth dose-dependently under both normoxic and hypoxic conditions. The level of CA9 and VEGF mRNAs decreased in the melanoma cells when treated with KCN1. The activity of reporter constructs were inhibited in the presence of KCN1 by 30-80%. KCN1 suppressed the protein expression of p-met, p-MAPK and p-STAT3 dose-dependently, and also significantly reduced the level of VEGF in the culture media from melanoma cells. In a mouse model of melanoma, KCN1 decreased the growth of primary ocular melanoma by up to 70% and reduced the formation of hepatic micrometastases by up to 50% in a dose-dependent manner. Furthermore, immunostaining showed decreased Ki67 and VEGF expression after treatment with KCN1.
Conclusions
Anti-tumor small molecule KCN1 reduced both in vitro growth and in vivo hepatic micrometastases of ocular melanoma. KCN1 is a potential therapeutic agent for the treatment of uveal melanoma. Further preclinical evaluation of KCN1 and related complexes is warranted.
Keywords: 744 tumors •
745 uvea •
503 drug toxicity/drug effects