BackgroundMetastasis is the most pivotal cause of mortality in cancer patients. Immune tolerance plays a crucial role in tumor progression and metastasis.Methods and FindingsIn this study, we investigated the potential roles and mechanisms of TLR2 signaling on tumor metastasis in a mouse model of intravenously injected B16 melanoma cells. Multiple subtypes of TLRs were expressed on B16 cells and several human cancer cell lines; TLR2 mediated the invasive activity of these cells. High metastatic B16 cells released more heat shock protein 60 than poor metastatic B16-F1 cells. Importantly, heat shock protein 60 released by tumor cells caused a persistent activation of TLR2 and was critical in the constitutive activation of transcription factor Stat3, leading to the release of immunosuppressive cytokines and chemokines. Moreover, targeting TLR2 markedly reduced pulmonary metastases and increased the survival of B16-bearing mice by reversing B16 cells induced immunosuppressive microenvironment and restoring tumor-killing cells such as CD8+ T cells and M1 macrophages. Combining an anti-TLR2 antibody and a cytotoxic agent, gemcitabine, provided a further improvement in the survival of tumor-bearing mice.Conclusions and SignificanceOur results demonstrate that TLR2 is an attractive target against metastasis and that targeting immunosuppressive microenvironment using anti-TLR2 antibody is a novel therapeutic strategy for combating a life-threatening metastasis.

Recent reports have shown that peroxisome proliferatoractivated receptor (PPAR

BACKGROUND.It was recently reported that high expression of peroxisome proliferator‐activated receptor γ (PPARγ) and low expression of cyclooxygenase‐2 (COX‐2) might be involved in the inhibition of ovarian tumor progression and confirmed that PPARγ activation could suppress COX‐2 expression via the nuclear factor‐κB pathway in ovarian cancer cells.METHODS.The current study investigated whether meloxicam, a selective COX‐2 inhibitor, and ciglitazone, a ligand for PPARγ, inhibit the growth of human ovarian cancer cell lines and aimed to elucidate the molecular mechanism of their antitumor effect. Tumor growth and survival were examined in female nu/nu mice xenografted with subcutaneous OVCAR‐3 tumors or with intraperitoneal DISS tumors and treated with meloxicam (162 ppm in diet, every day) or ciglitazone (15 mg/kg intraperitoneally once a week).RESULTS.Both meloxicam and ciglitazone treatments significantly suppressed the growth of OVCAR‐3 tumors xenotransplanted subcutaneously and significantly prolonged the survival of mice with malignant ascites derived from DISS cells as compared with controls. Meloxicam treatment decreased COX‐2 expression in tumors by 2.5‐fold compared with that observed in untreated tumors. Although ciglitazone treatment did not alter COX‐2 expression in tumors, it reduced the expression of microsomal prostaglandin (PG) E synthase, which converts COX‐derived PGH2 to PGE2. Both meloxicam and ciglitazone decreased PGE2 levels in serum as well as in ascites. Reduced microvessel density and induced apoptosis were found in solid OVCAR‐3 tumors treated with either meloxicam or ciglitazone.CONCLUSIONS.These results indicate that both meloxicam and ciglitazone produce antitumor effects against ovarian cancer in conjunction with reduced angiogenesis and induction of apoptosis. Cancer 2007; 110:791–800. © 2007 American Cancer Society.

These results indicate that intracellular and extracellular HSP70 have different roles in the regulation of cardiac remodelling and function in response to hypertension. Extracellular HSP70 is a potential therapeutic target against cardiac hypertrophy and fibrosis.

In this study, we investigated the inhibitory effect of clofibric acid (CA), a ligand for peroxisome proliferatoractivated receptor (PPAR)α, and pioglitazone, a ligand for PPARγ, on ovarian cancer in in vivo experiments using human ovarian cancer cell lines, and we aimed to elucidate the molecular mechanism of their anticancer effect. The antitumor effects of CA (3,000 ppm in the daily diet), pioglitazone (240 ppm in the daily diet) or the combination were studied in female nu/nu mice, xenografted with subcutaneous OVCAR-3 tumors or with intraperitoneal DISS tumors. The tumor tissues were quantified for expression levels of AP-1, cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) using Western blot analysis or immunohistochemistry. CD-31-stained microvessel density (MVD) was measured in the tumors. The induction of apoptosis was quantified by the TUNEL method. Treatment with CA or pioglitazone significantly suppressed the growth of subcutaneously xenotransplanted OVCAR-3 tumors and prolonged the survival of mice with malignant ascites derived from DISS cells as compared to the control. Combination of both agents enhanced the anticancer effect. Increase of apoptosis and necrosis as well as decrease of VEGF expression and MVD were found in solid OVCAR-3 tumors treated with CA, pioglitazone or the combination. The combination significantly induced apoptotic cells, compared to CA or pioglitazone alone. The combination significantly reduced expression of AP-1, which is a transcriptional regulator of COX-2, and also significantly decreased COX-2 expression in OVCAR-3 tumors compared to the control, CA or pioglitazone alone, although CA or pioglitazone alone decreased them with a marginal significance compared to the control. These findings indicate that the combination of CA and pioglitazone produces a potent antitumor effect on ovarian cancer through reduction of AP-1 expression.

Hypertension-induced cardiovascular hypertrophy and fibrosis are critical in the development of heart failure. The activity of TLRs has been found to be involved in the development of pressure overload-induced myocardial hypertrophy and cardiac fibrosis. We wondered whether vaccine bacillus Calmette-Guérin (BCG), which activated TLR4 to elicit immune responses, modulated the pressure overload-stimulated cardiovascular hypertrophy and cardiac fibrosis in the murine models of abdominal aortic constriction (AAC)-induced hypertension. Before or after AAC, animals received BCG, TLR4 agonist, IFN-γ, or TLR4 antagonist i.p. BCG and TLR4 agonist significantly prevented AAC-induced cardiovascular hypertrophy and reactive cardiac fibrosis with no changes in hemodynamics. Moreover, TLR4 antagonist reversed the BCG- and TLR4 agonist-induced actions of anti-cardiovascular hypertrophy and cardiac fibrosis. BCG decreased the expression of TLR2 or TLR4 on the heart tissue but TLR4 agonist increased the expression of TLR2 or TLR4 on the immune cells that infiltrate into the heart tissue. This led to an increased expression ratio of IFN-γ/TGF-β in the heart. The cardiac protective effects of BCG and TLR4 agonist are related to their regulation of ERK-Akt and p38-NF-κB signal pathways in the heart. In conclusion, the activity of TLR4 plays a critical role in the mediation of pressure overload-induced myocardial hypertrophy and fibrosis. The regulation of immune responses by BCG and TLR4 agonist has a great potential for the prevention and treatment of hypertension-induced myocardial hypertrophy and cardiac fibrosis.

Purpose We have recently reported that peroxisome proliferator-activated receptor gamma (PPARc) ligands produce antitumor effects against human ovarian cancer in conjunction with reduction in angiogenesis and induction of apoptosis via regulating prostaglandin (PG) E 2 level. In this study, we investigated the effects of combination of ciglitazone, a PPARc ligand, and cisplatin, a cytotoxic anticancer drug, on growth of ovarian cancer. Methods Tumor growth and survival were examined in female nu/nu mice xenografted with subcutaneous OV-CAR-3 tumors or with intraperitoneal DISS tumors and treated with cisplatin alone (5 mg/kg intraperitoneally once on day 1), ciglitazone alone (15 mg/kg intraperitoneally once a week), or the combination. Results Ciglitazone alone, cisplatin alone, or their combination significantly suppressed the growth of OVCAR-3 tumors xenotransplated subcutaneously and prolonged the survival of mice with malignant ascites derived from DISS cells as compared with the control. Furthermore, the combination produced a significantly greater antitumor effect than cisplatin or ciglitazone alone and also significantly prolonged the survival time as compared with cisplatin or ciglitazone alone. The combination significantly decreased PGE 2 concentration in serum as well as in ascites, reduced vascular endothelial growth factor as well as microvessel density, and induced apoptosis in solid OVCAR-3 tumor as compared with cisplatin or ciglitazone alone. The combination remarkably decreased the expression of cyclooxygenase-2 (COX-2), microsomal PG E synthase (mPGES), and PG receptor 3 (EP3) in tumors.In vitro experiment showed that ciglitazone enhances the cytotoxicity of cisplatin against ovarian cancer cells. Conclusion In conclusion, the combination inhibited the growth of ovarian cancer in conjunction with reduction in angiogenesis and induction of apoptosis resulting from suppression of PGE 2 activation through decreasing the expression of COX-2, mPGES, and EP3. The inhibitory effect of this combination treatment on growth of ovarian cancer suggests a potential to lead a novel therapeutic strategy against ovarian cancer.

Many reports have demonstrated that non-steroidal anti-inflammatory drugs (NSAIDs) suppress malignant transformation and tumor growth, and some NSAIDs are expected to be new anti-cancer agents. In this study, we examined the anti-tumor effects of the non-specific cyclooxygenase (COX) inhibitors aspirin and piroxicam, and the selective COX-2 inhibitor meloxicam on xenotransplanted ovarian cancer. Tumor growth and survival were compared in female nu/nu mice, xenografted with subcutaneous OVCAR-3 tumors or with intraperitoneal DISS tumors and treated with aspirin (200 ppm in diet, everyday), piroxicam (150 ppm in diet, everyday) or meloxicam (162 ppm in diet, everyday). Al, of the agents tested significantly suppressed the growth of OVCAR-3 tumors xenotransplanted subcutaneously as compared to the control. There was a significant difference in inhibition of OVCAR-3 tumor growth between meloxicam and aspirin treatment. Meloxicam and piroxicam treatment significantly prolonged survival of mice with malignant ascites derived from DISS cells as compared to control and aspirin treatment. Mice treated with meloxicam survived significantly longer than those treated with piroxicam. There was no significant difference in survival between control and aspirin treatment. Necropsy revealed that one of the 6 cancer-bearing mice treated with piroxicam suffered from stomach perforation. These results indicate that a selective COX-2 inhibitor produces greater anti-tumor effect against ovarian cancer than a nonselective COX inhibitor and that meloxicam may have a potential of leading to a novel therapeutic strategy against ovarian cancer.