Inhibition of spontaneous metastases formation by amifostine

Abstract

Amifostine was investigated for its ability to inhibit spontaneous metastases formation using the well-characterized murine sarcoma, Sa-NH. Amifostine was administered intraperitoneally at a dose of 50 mg/kg every other day for 6 days to C3Hf/Kam mice until tumors reached an average size of 8 -8.5 mm in diameter. Amifostine was again administered immediately after surgical removal of the tumor-bearing limbs by amputation, and then once more 2 days later. Twenty-one days later, animals were evaluated for the presence of spontaneously developed pulmonary metastases. Nontumorbearing control animals were sham treated using the same dosing and surgery schedules. Treatment with amifostine appeared to slightly delay tumor growth, that is, 13 vs. 12 days for tumors to reach an average diameter of 8 mm. Amifostine reduced both the incidence of pulmonary metastases formed in experimental animals from 77% to 57% (p < 0.05), and their average number per animal from 12.8 ؎ 5.4 (SEM) to 2.9 ؎ 1.1 (SEM). The effect of amifostine exposure on serum levels of the angiogenesis inhibitor angiostatin was also determined using Western blot analysis. Consistent with the antimetastatic effect, exposure of animals to 50 mg/kg of amifostine resulted in a 4-fold enhanced serum level of angiostatin above control levels. This phenomenon occurred in tumor-bearing and nontumor-bearing animals. The effects of amifostine on matrix metalloproteinase (MMP) enzymatic activity was also determined using gelatin zymography. Conditioned growth medium collected from Sa-NH cells grown to confluency was exposed to various concentrations of SH, i.e.

Amifostine Inhibits Angiogenesis in Vivo

“…Taking into account that embryonic angiogenesis may differ in several aspects from human tumor angiogenesis in the adult, further studies are in progress using other angiogenesis models. An antimetastatic (Grdina et al, 2002) and an antiangiogenic (this study) action of amifostine, in addition to its radioprotective effects, further support the use of amifostine in combination with radiotherapy for increased therapeutic efficacy.…”

“…In the present study we showed that amifostine decreased proMMP-2 mRNA levels, although it did not affect the total amounts or the activity of MMP-2 in CAM protein extracts. A decrease of MMP-2 protein amounts and activity has been observed in tumor cells (Grdina et al, 2002), as well as in human endothelial cells (E. Giannopoulou and E. Papadimitriou, unpublished observations). The discrepancy between the effect of amifostine on the mRNA and the protein levels of MMP-2 could be due to a concomitant effect of amifostine on the amounts of membrane type 1 MMP or the inhibitor of MMP-2, tissue inhibitor of metalloproteinase 2.…”

“…In the present work, we showed a dose-dependent inhibition of angiogenesis in the chicken embryo CAM, which is supported by the effects of amifostine on several molecules implicated in angiogenesis. In agreement with an antiangiogenic effect of amifostine are studies that show that it down-regulates cell cycle progression (North et al, 2000), represses c-myc gene expression (Liu et al, 1997), inhibits topoisomerase II activity (Snyder and Grdina, 2000), increases the plasma levels of angiostatin (Grdina et al, 2002), and decreases MMP-2 activity (Grdina et al, 2002).…”

“…In normal cells, polyamine generation is not up-regulated and the disulfide is actively imported into the cell, affording resistance to apoptosis induction (List and Gerner, 2000;Quinones et al, 2002). Preclinical data indicate that amifostine can reduce the risk of secondary cancers caused by radiation and certain forms of chemotherapy (Dorr, 1998) and inhibits the formation of spontaneous metastases (Grdina et al, 2002).…”

Induction of apoptosis in human lung cancer cells following treatment with amifostine and an adenoviral vector containing wild-type p53

“…19 In addition, amifostine increased angiostatin and decreased matrix metalloproteinase production in a murine sarcoma model, resulting in a subsequent 20% decrease in pulmonary metastases. 20 The role of p53 in modulating the dual roles that amifostine has as both a cytoprotectant and as an antitumor agent has been explored, with conflicting results. Amifostine was found to activate the tumorsuppressor protein p53 and induce expression of the cyclin-dependent kinase inhibitor p21 WAF1 in the presence of a functional p53 in the breast cancer cell line MCF-7 …”