Growth inhibition of ras-dependent tumors in nude mice by a potent ras-dislodging antagonist

✍ Scribed by Yaakov Egozi; Boaz Weisz; Mali Gana-Weisz; Gilad Ben-Baruch; Yoel Kloog

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: French
• Weight: 181 KB
• Volume: 80
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/(sici)1097-0215(19990315)80:6<911::aid-ijc18>3.0.co;2-4

✦ Synopsis

A lipophilic farnesyl moiety attached to the carboxyl terminal cysteine of ras proteins structurally supports their membrane anchorage, required for ras-dependent growth-factor signaling and for transforming activity of ras oncoproteins. It has been shown that inhibition of ras farnesylation can block tumor growth in nude mice but that some ras-dependent tumors escape such blockage as a result of prenylation of ras. S-trans-transfarnesylthiosalicylic acid (FTS) is a potent rasdislodging antagonist that does not affect ras prenylation but rather acts on the mature, membrane-bound ras and facilitates its degradation. Here we demonstrate that FTS induces reappearance of stress fibers in H-ras-transformed rat-1 cells (EJ cells) in vitro, inhibits their anchorage-independent growth in vitro, and blocks EJ-tumor growth in nude mice. The anchorage-independent growth of cells expressing ErbB2 (B104), but not that of v-raf-transformed cells, is also inhibited by FTS, suggesting specificity towards activated ras. FTS treatment (5 mg/kg i.p. daily) caused inhibition (75-80%) of tumor growth in nude mice implanted with EJ, but not in mice implanted with v-raf-transformed cells, with no evidence of systemic toxicity. Moreover, FTS treatment increased the survival rate of EJ-tumor-bearing mice from 48 to 68 days. Here we demonstrate anti-tumor potency in a synthetic, non-toxic, ras-dislodging antagonist acting independently of farnesyltransferases.