سیما سیف آبادی

Endothelial progenitor cells (EPCs) play an important role in tumor growth and angiogenesis. Punica granatum، from Punicaceae family، has demonstrated anticancer effects in different types of cancers. This study aimed to determine the effect of hydroalcoholic extract of pomegranate peel on the number of EPCs in mouse model of melanoma and also to determine its mechanism of action.

The hydroalcoholic extract of black pomegranate pericarp was prepared using 70% ethanol containing 1% acetic acid. 1 × 106 B16F10 melanoma cells were injected to each of 88 C57BL6 male mice weighing 25 g on the day 0، subcutaneously (s. c). On 7th day، mice were randomly divided into 11 groups of 8 animals. The first group (control) received distilled water. Groups second to fifth from the seventh day of the study received 50، 100، 200 and 400 mg/kg of standardized polyphenon E (PPE) via gavage. The sixth group received PPE and peroxisome proliferator-activated receptor gamma (PPAR-γ) antagonist (5 mg/kg/day) intraperitoneally. The seventh group received PPE and PPAR-α antagonist (10 mg/kg/day) intraperitoneally. Eighth and ninth groups received fenofibrate (100 mg/kg) and rosiglitazone (100 mg/kg) as agonists of PPAR-α and PPAR-γ، respectively، via gavage. Tenth and eleventh groups received PPAR antagonists، merely. On 16th day، mice were euthanized and were bled through heart puncture for EPC enumeration via flow cytometry. In flow cytometry، CD34+/VEGFR2+ cells were enumerated.

PPE dose-dependently decreased the number of EPCs (P < 0. 05). Number of EPCs in the groups which received fenofibrate and rosiglitazone was less than the group that received the highest dose of PPE (P < 0. 05). Moreover، EPCs in the groups which received both PPAR antagonists and PPE، was more than the group which received PPE (P < 0. 01).

In conclusion، we demonstrated that PPE is effective in reducing the number of EPCs and part of this effect is through modulation of PPAR pathway.

Angiogenesis is the process of formation of new capillaries from the preexisting vessels and plays an important role in the growth and metastasis of tumor. In this study، we aimed to investigate the antiangiogenic effect of hydroalcoholic extract of black pomegranate pericarp extract (PPE) in the animal model of melanoma.

The hydroalcoholic extract of black pomegranate pericarp was prepared using 70% ethanol containing 1% acetic acid. 1 × 106 B16F10 melanoma cells were injected to all mice on the day 0، subcutaneously (s. c). On 7th day، mice were divided into 9 groups of 8 animals. The first group received distilled water. Groups second to fifth received 50، 100، 200 and 400 mg/kg of black pomegranate pericarp extract. The sixth group received the extract and peroxisome proliferator-activated receptor gamma (PPAR-γ) antagonist (5 mg/kg/day). The seventh group received the extract and PPAR-α antagonist (10 mg/kg/day). Eighth and ninth groups received fenofibrate (100 mg/kg) and rosiglitazone (100 mg/kg) as agonists of PPAR-α and PPAR-γ، respectively. On 16th day، mice were euthanized and their tumor samples were weighed and then analyzed via immunohistochemistry staining for CD31.

The black pomegranate pericarp extract dose dependently decreased tumor weight and angiogenic marker (P < 0. 05). Moreover، tumor weight and angiogenic marker in the groups which received both peroxisome proliferator-activated receptor antagonists and black pomegranate pericarp extract، was more than the group which received the extract (P < 0. 001). Level of angiogenesis and tumor weight in the groups which received fenofibrate and rosiglitazone was less than the group that received the highest dose of pomegranate pericarp extract (P < 0. 05).

Taken together، our observations suggest that black pomegranate pericarp extract may have potential implication in melanoma cancer treatment، and show that antiangiogenic effect of this extract may be mediated through modulation of peroxisome proliferator-activated receptor activation pathways.