Usefulness of melatonin as complementary to chemotherapeutic agents at different stages of the angiogenic process.

Chemotherapeutics are sometimes administered with drugs, like antiangiogenic compounds, to increase their effectiveness. Melatonin exerts antitumoral actions through antiangiogenic actions. We studied if melatonin regulates the response of HUVECs to chemotherapeutics (docetaxel and vinorelbine). The inhibition that these agents exert on some of the processes involved in angiogenesis, such as, cell proliferation, migratory capacity or vessel formation, was enhanced by melatonin. Regarding to estrogen biosynthesis, melatonin impeded the negative effect of vinorelbine, by decreasing the activity and expression of aromatase and sulfatase. Docetaxel and vinorelbine increased the expression of VEGF-A, VEGF-B, VEGF-C, VEGFR-1, VEGFR-3, ANG1 and/or ANG-2 and melatonin inhibited these actions. Besides, melatonin prevented the positive actions that docetaxel exerts on the expression of other factors related to angiogenesis like JAG1, ANPEP, IGF-1, CXCL6, AKT1, ERK1, ERK2, MMP14 and NOS3 and neutralized the stimulating actions of vinorelbine on the expression of FIGF, FGFR3, CXCL6, CCL2, ERK1, ERK2, AKT1, NOS3 and MMP14. In CAM assay melatonin inhibited new vascularization in combination with chemotherapeutics. Melatonin further enhanced the chemotherapeutics-induced inhibition of p-AKT and p-ERK and neutralized the chemotherapeutics-caused stimulatory effect on HUVECs permeability by modifying the distribution of VE cadherin. Our results confirm that melatonin blocks proangiogenic and potentiates antiangiogenic effects induced by docetaxel and vinorelbine enhancing their antitumor effectiveness.

Dietary hemin promotes colonic preneoplastic lesions and DNA damage but not tumor development in a medium-term model of colon carcinogenesis in rats.

Red and processed meat consumption has been strongly related to increase the risk of colorectal cancer (CRC), although its impact is largely unknown. Hemin, an iron-containing porphyrin, is acknowledged as a putative factor of red and processed meat pro-carcinogenic effects. The aim of this study was to investigate the effects of high dietary hemin on the promotion/progression stages of 1,2-dimethylhydrazine (1,2-DMH)-induced colon carcinogenesis. Twenty-four Wistar male rats were given four subcutaneous 1,2-DMH injections and received either balanced diet or balanced diet supplemented with hemin 0.5 mmol/kg for 23 weeks. Colon specimens were analyzed for aberrant crypt foci (ACF) and tumor development. Dietary hemin significantly increased ACF number and fecal water cytotoxicity/genotoxicity in Caco-2 cells when compared to 1,2-DMH control group. However, tumor incidence, multiplicity and cell proliferation did not differ between 1,2-DMH + hemin and 1,2-DMH control group. Gene expression analysis of 91 target-genes revealed that only three genes (Figf, Pik3r5 and Tgfbr2) were down-regulated in the tumors from hemin-fed rats compared to those from 1,2-DMH control group. Therefore, the findings of this study show that high hemin intake promotes mainly DNA damage and ACF development and but does not change the number nor incidence of colon tumors induced by 1,2-DMH in male rats.

Growth factor therapy and autologous lymph node transfer in lymphedema.

BACKGROUND: Lymphedema after surgery, infection, or radiation therapy is a common and often incurable problem. Application of lymphangiogenic growth factors has been shown to induce lymphangiogenesis and to reduce tissue edema. The therapeutic effect of autologous lymph node transfer combined with adenoviral growth factor expression was evaluated in a newly established porcine model of limb lymphedema. METHODS AND RESULTS: The lymphatic vasculature was destroyed within a 3-cm radius around an inguinal lymph node. Lymph node grafts and adenovirally (Ad) delivered vascular endothelial growth factor (VEGF)-C (n=5) or VEGF-D (n=9) were used to reconstruct the lymphatic network in the inguinal area; AdLacZ (ß-galactosidase; n=5) served as a control. Both growth factors induced robust growth of new lymphatic vessels in the defect area, and postoperative lymphatic drainage was significantly improved in the VEGF-C/D-treated pigs compared with controls. The structure of the transferred lymph nodes was best preserved in the VEGF-C-treated pigs. Interestingly, VEGF-D transiently increased accumulation of seroma fluid in the operated inguinal region postoperatively, whereas VEGF-C did not have this side effect. CONCLUSIONS: These results show that growth factor gene therapy coupled with lymph node transfer can be used to repair damaged lymphatic networks in a large animal model and provide a basis for future clinical trials of the treatment of lymphedema.