esculetin and Neoplasm-Metastasis

Tumor growth and metastasis are closely associated with the M2 macrophage activation of tumor-associated macrophages (TAMs) in the tumor microenvironment as well as the development of tumor cells. In this study, we examined the antiproliferative, antitumor, and antimetastatic effects of three dihydroxycoumarins (esculetin, fraxetin, and daphnetin) against osteosarcoma LM8 cells (in vitro) and a highly metastatic model in LM8-bearing mice (in vivo). Esculetin (20-100μM) inhibited the proliferation of LM8 cells, whereas fraxetin and daphnetin had no effect. Esculetin inhibited the expressions of cyclin D1, cyclin-dependent kinase (CDK) 4 and matrix metalloproteinase (MMP)-2, and production of both transforming growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF) in LM8 cells. Esculetin (3 or 10mg/kg) and fraxetin (10mg/kg) inhibited tumor growth and metastasis to the lung or liver, whereas daphnetin did not. These results suggested that the antitumor and antimetastatic actions of esculetin may be partly attributed to G1 arrest by the inhibition of cyclin D1 and CDK4 expression, while its antiangiogenic action may have been due to the inhibition of MMP-2 expression and TGF-β1 and VEGF productions at tumor sites. Esculetin (10-100μM) and fraxetin (50-100μM) inhibited the production of interleukin (IL)-10, monocyte chemoattractant protein (MCP)-1, and TGF-β1 during the differentiation of M2 macrophages by reducing the phosphorylation of Stat 3 without affecting its expression. These results also suggested that the antitumor and antimetastatic actions of esculetin or fraxetin may be due to the regulated activation of TAM by M2 macrophage differentiation in the tumor microenvironment.

Topics: Animals; Antineoplastic Agents; Apoptosis; Body Weight; Cell Differentiation; Cell Line, Tumor; Cell Polarity; Cell Proliferation; Chemokine CCL2; Coumarins; Cyclin-Dependent Kinase 4; G1 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Humans; Interleukin-10; Macrophage Activation; Macrophages; Male; Matrix Metalloproteinase 2; Mice; Neoplasm Metastasis; Osteosarcoma; STAT3 Transcription Factor; Tetradecanoylphorbol Acetate; Transforming Growth Factor beta1; Umbelliferones; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays

Diets rich in linoleic acid (LA) stimulate the metastasis of MDA-MB-435 human breast cancer cells from the mammary fat pads of nude mice. This omega-6 fatty acid is metabolized to various cyclo-oxygenase and lipoxygenase products, several of which have been previously associated with tumor cell invasion and metastasis. We now report that MDA-MB-435 cells secreted increased levels of prostaglandin E2 (PGE2), and 12-hydroxyeicosatetraenoic acid (12-HETE) and 15-HETE when cultured in the presence of 2.7 microM (0.75 micrograms/ml) LA; 5-HETE secretion was unchanged. The 12-lipoxygenase inhibitor esculetin (20 microM) completely blocked the LA-stimulated 12-HETE secretion. Linoleic acid also increased MDA-MB-435 cell invasion in an in vitro assay; this stimulation was abolished by 20 microM esculetin, but was unaffected by piroxicam, a selective cyclooxygenase inhibitor. The effect of LA on invasion was replicated by 0.1 microM 12-HETE, but not by 5-HETE or PGE2; 15-HETE was stimulatory only at a concentration of 1.0 microM. Zymographic and Northern blot analyses showed that these events are accompanied by the induction of 92 kDa isoform type IV collagenase (metalloproteinase-9) enzymic activity and mRNA expression by exogenous LA and 12-HETE, and their suppression by the 12-lipoxygenase inhibitor. These results suggest that the effects of dietary LA on breast cancer cell metastasis in the nude mouse model are due, at least in part, to enhanced 12-HETE biosynthesis, with an associated increase in proteolytic enzyme activity and tumor cell invasiveness.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Breast Neoplasms; Collagenases; Eicosanoids; Gene Expression; Humans; Hydroxyeicosatetraenoic Acids; Linoleic Acid; Linoleic Acids; Lipoxygenase Inhibitors; Matrix Metalloproteinase 9; Neoplasm Invasiveness; Neoplasm Metastasis; Piroxicam; RNA, Messenger; Tumor Cells, Cultured; Umbelliferones

Metastasis is a complex process, almost a cascade, involving multiple steps and activities. However, an important factor is that malignant cells are able to penetrate through the multiple basement membrane barriers surrounding tissues, blood vessels, nerves and muscle that would otherwise block their dissemination. Penetration of malignant tumor cells through basement membrane is an active process requiring proteolysis. We report here that inhibitors of both the cyclooxygenase and lipoxygenase pathways of arachidonic acid metabolism convert mouse melanoma and human fibrosarcoma cells to a non invasive state by reducing the production of MMP-2, an enzyme required for the degradation of basement membranes. Specific metabolites of each pathway, i.e. PGF2 alpha and 5-HPETE, are able to transcend the block and restore collagenase production, invasiveness in vitro and metastatic activity in vivo. These studies indicate a key role for arachidonic acid metabolites in metastasis and suggest novel therapeutic approaches for inhibiting the spread of cancer.

Topics: Animals; Arachidonic Acid; Caffeine; Collagen; Cyclooxygenase Inhibitors; Dinoprost; Drug Combinations; Extracellular Matrix; Fibrosarcoma; Gelatinases; Humans; Indoles; Indomethacin; Laminin; Leukotrienes; Lipoxygenase Inhibitors; Masoprocol; Matrix Metalloproteinase 2; Melanoma; Metalloendopeptidases; Mice; Neoplasm Metastasis; Proteoglycans; Tumor Cells, Cultured; Umbelliferones