Macrophage monocultures previously incubated in the presence of CTX displayed increased LXA4 secretion (59% at 24 h, Fig. 6B). Differences in the levels of LXA4 were not observed at 12 h (Fig. 6A) or at 48 h (Fig. 6C). In contrast,

CTX enhanced the 15-epi-LXA4 production by macrophage monocultures in all the time periods evaluated (9.3-fold at 12 h, Fig. 6D; 5.5-fold at 24 h, Fig. 6E; 2.7-fold at 48 h, Fig. 6F), compared to control monocultures. The supernatants of co-cultures of macrophages pre-incubated with CTX and LLC-WRC 256 cells produced significantly increased LXA4 levels only at 24 h (25%, Fig. 6B). Differences in the levels of LXA4 in the co-cultures of CTX-treated macrophages and tumour cells were not observed at 12 h (Fig. 6A) or 48 h (Fig. 6C). As shown in Fig. 6D, treatment with CTX did MEK inhibitor not affect the levels of 15-epi-LXA4 secreted by the macrophages in co-cultures with the tumour cells. However, the 15-epi-LXA4 levels were gradually induced over 24 h (2.3-fold,

Fig. 6E) and 48 h (2.1-fold, Fig. 6F), when compared to the controls (co-cultures with macrophages pre-incubated with culture medium and LLC-WRC 256 tumour cells). The level of 15-epi-LXA4 in the LLC-WRC 256 cell monocultures was below the limits of sensitivity of the assay that was used (data not shown). In this study, an experimental model represented by macrophages cultivated together with tumour cells at a 10:1 ratio was used to evaluate the secretory activity of macrophages pre-treated with CTX growing in contact with tumour cells and the influence of Bortezomib concentration this contact on tumour cell proliferation. The data presented here demonstrate that macrophages pre-treated with CTX (0.3 μg/mL) for 2 h increased their release or secretion of effector molecules such as H2O2, NO and cytokines and exhibited a cytotoxic effect on tumour cells. It is important to mention that the proliferation and nitric oxide production assays was determined using macrophages co-cultivated

with three different tumour cell lines, such as, LLC-WRC 256 tumour cells, B16F10 murine melanoma cells and human breast cancer cell line MCF-7. Likewise that observed in the co-cultures GNA12 with LLC-WRC 256 cells, macrophages pre-treated with CTX, inhibited proliferation of B16–F10 and MCF-7 (31% and 38%, respectively, data not shown). Additionally, an increase of production of NO in these co-cultures (26% and 50%, respectively, data not shown) was observed. Therefore, since the same effect observed regardless the tumour cell type, only the LLC WRC 256 lineage was performed in subsequent evaluation. As shown in Fig. 1A, a marked induction of H2O2 liberation by CTX was observed after 24 h in both macrophage monocultures and co-cultures. After this period, liberation of H2O2 occurs in lower levels. Treating the macrophages with CTX resulted in an increased production of NO after 48 h of culture, as shown in Fig. 1B.