In vitro and in vivo anti‐tumor activity of L‐glutamic acid γ‐monohydroxamate against L1210 leukemia and B16 melanoma

Abstract

A glutamine analogue, L-glutamic acid gamma-monohydroxamate (GAH) demonstrated complete cytotoxicity against L1210 cells in culture and marked anti-tumoral activity in vivo against L1210 leukemia and B16 melanoma. In vitro, GAH caused concentration-dependent inhibition of L1210 cell growth, with complete cell death being reached at 72 hr and at a 500 microM concentration. A minimal incubation time of 38 hr with 500 microM GAH was necessary to obtain complete cell death at 72 hr. During incubation, GAH is metabolized to hydroxylamine. Hydroxylamine acts as the active form of GAH, since the concentration-dependent inhibition of cell growth caused by hydroxylamine is the same as that observed with GAH. The cytotoxic effects of GAH and hydroxylamine on L1210 cells were not reversed or prevented by L-glutamine or L-glutamic acid and purine nucleosides but were prevented or reversed by pyruvate, 2-oxaloacetate and 2-oxoglutarate. In vivo, GAH considerably increased survival of mice bearing L1210 leukemia or a solid tumor, the B16 melanoma. Antitumor activity of GAH against L1210 leukemia and B16 melanoma was schedule-dependent. The administration of GAH 3 times daily was more effective than a twice daily treatment and the maximum ILS was observed using split-dose schedules on days 1 through 3 and 7 through 9 without noticeable toxicity. Under these conditions hydroxylamine is highly toxic, suggesting that in vivo GAH might act as an hydroxylamine releaser in the tumor cells and is not significantly metabolized in the body.

l-Glutamic Acid γ-Monohydroxamate

“…Monoamino acid hydroxamates are simple, nontoxic derivatives of amino acids. D-Aspartic acid ␤-hydroxamate was shown to have antitumoral activity on murine leukemia L5178Y, both in vitro and in vivo, and is active against Friend leukemia cells in vitro as well (35). L-Glu(␥)HXM is cytotoxic against L1210 cells in culture and remarkably antitumoral against L1210 leukemia and B16 melanoma in vivo (35,36).…”

Inhibition of malate‐aspartate shuttle by the antitumor drug L‐glutamic acid α‐monohydroxamate in L1210 leukemia cells

“…In vitro GAH caused a concentration-dependent inhibition of L1210 cellgrowth, with complete cell death at 72 hr and at a 1 mM concentration. Furthermore, the fact that the cytotoxic activity of GAH could be reversed by pyruvate and selected 2-oxocarboxylic acids led us to hypothesize that a modification of the ratio of reduced to oxidized cytosolic pyridine nucleotides (NADHINAD+) could be involved in the cytotoxicity mechanism of GAH (Vila et al, 1990). In mammalian cells the sustained oxidation of some important substrates depends on a continuous supply of cytosolic NAD+.…”

Anti‐tumoral activity of L and D isomers of aspartic acid β‐hydroxamate on L5178Y leukemia

“…The possibility that there may be qualitative biological differences in asparagine metabolism between tumors and normal tissues deserves investigation since these may allow therapeutic approaches using asparagine analogues in cancer chemotherapy. Having previously described the cytocidal effects of amino-acid hydroxamate (Vila et al, 1990), we have now studied the in vitro and in vivo effects of L and D isomers of aspartic acid P-hydroxamate (LAH and DAH, respectively) on the L5178Y mouse leukemia which is totally devoid of L-asparagine synthetase activity and thus totally dependent on exogenous L-asparagine. …”