Efeito da fração proteolítica do látex de Vasconcellea cundinamarcensis, p1g10, sobre o processo inflamatório tumoral

Abstract

Previous studies demonstrated that P1G10, the proteolytic fraction from Vasconcellea cundinamarcensis latex, species native from South America, has antitumor and antimetastatic activity on different murine models. It acts by reducing TNF-a levels in ascitic fluid of Erhlich carcinoma and angiogenesis in murine melanoma. The aim of this study was to investigate the importance of the anti-inflammatory activity of P1G10 for the antitumoral effect. In 4T1 breast carcinoma model (inflammatory tumor) P1G10 (1, 3 e 5 mg/kg) reduced the tumor mass (51%) and at the dose of 1 mg/kg, increased the number of peripheral leukocytes (87%), as reflected by 140% increase of neutrophils and monocytes. However, P1G10 reduced leukocyte adhesion to small (46%) and large (52%) tumor vessels. These results were accompanied by decreases of tumor pro-inflammatory and pro-angiogenic cytokines, such as: MPC-1 (48%), IL-6 (63%), VEGF (47%) and KC/CXCL1 (53%); and by an increase in NAG activity (157%). During in vitro assays with cultured macrophages, P1G10 (5 - 50 g/mL) reduced VEGF production by 21-73 % as well as in macrophage/4T1 co-cultures by 18- 89%, after 24 h exposure. The effect of P1G10 on TNF- shows a dual effect. A 24-h exposure to P1G10 (5 - 50 g/mL) reduced the TNF- levels in single cultured macrophage (28 - 45 %), do not altering these levels in co-cultures. Exposure to P1G10 for 48 h increased the TNF- level only in the concentrations of 25 and 50 g/mL (12 and 20% respectively), in cultured macrophage or in co-cultures. These augment was measured by an increase in ratio between TNF- and the metabolism of these cultures (TNF- /D.O - 35%) or, by an increase in the ratio between the levels of this cytokine and the number of cell in co-culture (TNF-/ D.C - 31 and 123%, 25 and 50 g/mL, respectively), do not altering the absolute levels of TNF- . In cocultures, the increase in TNF- was accompanied by reduction 31 and 61% reduction in 4T1 cell number. The results show that P1G10 is able to inhibit tumor growth of tumor 4T1 cells. This ability is probably associated with the reduction of the inflammatory process, supported by reduction of leukocyte adhesion to tumor vessels and by reduction of pró-inflammatory/angiogenic cytokines in cultures and in tumors (in vivo). Furthermore, the decrease of tumor mass by P1G10 treatment can be attributed to the enhanced cytotoxic activity of macrophages, observed in co-cultures.