Figure 4. Oleate-induced autocrine production of PTX3 enhances tumor metastasis.

(A) TU183 cells were transfected with 20 nM PTX3 siRNA (siPTX3) or scrambled oligonucleotides by lipofection. A lung-colonization analysis was performed by injecting 1 × 10⁶ TU183 cells into the lateral tail vein of SCID mice. Prior to the injection, oleate was injected into the tail vein of mice to mimic the condition of patients who present with 400 μM circulating FFAs. Lung micronodules were examined and photographed after the mice were sacrificed at 6 weeks. The lungs and tumor tissues stained with H&E were examined under a microscope (left panel). The number of micronodules was counted under a microscope (right panel). Parental indicates TU183 cells, either with (N = 6) or without (N = 4) treatment with oleate. siPTX3 (siPTX3-1: N = 3, siPTX3-2: N = 3) indicates the knockdown of PTX3. The values represent the mean ± s.e.m. ***P <0.001. SC: scrambled oligonucleotides. (B-E) TU183 cells were transfected with 20 nM PTX3 siRNA oligonucleotides (siPTX3) and scrambled siRNA (SC) by lipofection, and the cells were treated with 400 μM oleate or anti-PTX3 antibodies (abPTX3) for 18 h. The cells were then labelled with CFSE and cultured with endothelial cells for 30 min. The bound tumor cells (adherent cells) were analyzed using a flow cytometer. TU183 cells were CFSE-positive, and endothelial cells were CFSE-negative. The bound tumor cells were quantified in three independent experiments by flow cytometry. The values are the mean ± s.e.m.