A new functional Ras antagonist inhibits human pancreatic tumor growth in nude mice

Abstract

Constitutively active Ras proteins, their regulatory components, and overexpressed tyrosine kinase receptors that activate Ras, are frequently associated with cell transformation in human tumors. This suggests that functional Ras antagonists may have anti-tumor activity. Studies in rodent ®broblasts have shown that S-trans, transfarnesylthiosalicylic acid (FTS) acts as a rather speci®c nontoxic Ras antagonist, dislodging Ras from its membrane anchorage domains and accelerating its degradation. FTS is not a farnesyltransferase inhibitor, and does not a ect Ras maturation. Here we demonstrate that FTS also acts as a functional Ras antagonist in human pancreatic cell lines that express activated KRas (Panc-1 and MiaPaCa-2). In Panc-1 cells, FTS at a concentration of 25 ± 100 mM reduced the amount of Ras in a dose-dependent manner and interfered with serumdependent and epidermal growth factor-stimulated ERK activation, thus inhibiting both anchorage-dependent and anchorage-independent growth of Panc-1 cells in vitro. FTS also inhibited tumor growth in Panc-1 xenografted nude mice, apparently without systemic toxicity. Daily FTS treatment (5 mg/kg intraperitoneally) in mice with tumors (mean volume 0.07 cm 3 ) markedly decreased tumor growth (after treatment for 18 days, tumor volume had increased by only 23+30-fold in the FTStreated group and by 127+66-fold in controls). These ®ndings suggest that FTS represents a new class of functional Ras antagonists with potential therapeutic value.

Farnesylthiosalicylic acid induces caspase activation and apoptosis in glioblastoma cells

“…These studies showed that the LD 50 of FTA was between 75 and 100 mg/ kg. 34 Intraperitoneal administration of FTA (5 mg per kg) in mice did not significantly affect body weight or weights of the adrenal gland, spleen, heart, kidney, liver, and pancreas. 34 Similarly, FTA did not affect blood counts (erythrocytes, leukocytes, or platelets), creatine, liver enzymes, or creatine kinase (all isoforms).…”

“…34 Intraperitoneal administration of FTA (5 mg per kg) in mice did not significantly affect body weight or weights of the adrenal gland, spleen, heart, kidney, liver, and pancreas. 34 Similarly, FTA did not affect blood counts (erythrocytes, leukocytes, or platelets), creatine, liver enzymes, or creatine kinase (all isoforms). 33 In another study, FTA inhibited melanoma tumor growth by 90% with no observable (15,30,60 min, 3 and 6 h) for the activation of MAPK and Akt were determined first.…”

“…24 This specific action of FTA is claimed to be responsible for the lack of cytotoxicity in vivo. 34 In animal studies, FTA has been demonstrated to be relatively safe. 34,35 The lack of overt toxic effects in these animals indicates that FTA has a reasonable large margin of safety.…”

“…34 In animal studies, FTA has been demonstrated to be relatively safe. 34,35 The lack of overt toxic effects in these animals indicates that FTA has a reasonable large margin of safety. These studies showed that the LD 50 of FTA was between 75 and 100 mg/ kg.…”

“…34,35,41 FTA crosses the blood-brain barrier and a pharmacologically relevant concentration (4.5 mmol/l) of the inhibitor could be rapidly reached (30-120 min) following systemic administration of 3 mg/kg of the novel Ras inhibitor. 41 In this study, FTA provided neuroprotection through the inhibition of active Ras in the brain.…”