Growth of methionine-dependent human prostate cancer (PC-3) is inhibited by ethionine combined with methionine starvation

Abstract

Summary Methionine (MET) is required for cell metabolism. MET endogenously synthesized from homocysteine (HCY) supports the proliferation of normal cells, but not that of numerous malignant cells, as shown previously. MET starvation should have an anti-tumour effect, and its deleterious effects on the hosts might be prevented by HCY. Anti-tumour effects of MET starvation must be reinforced by ethionine (ETH), a MET analogue. MET dependency of PC-3, a human prostate cancer cell line, was studied in vitro. Proliferation of PC-3 cells, cultivated in MET-free medium, was 29% compared with growth in MET+HCY-medium. Addition of HCY to MET-free medium increased the proliferation rate to 56%. The concentration of ETH required to decrease the PC-3 cell proliferation rate to 50% (IC50) was 0.5 mg ml-1 in MET-HCY-medium. ETH-induced inhibition was abolished by MET addition and was reinforced by HCY. PC-3 cell cycle was blocked in the S-G2-phase after 30 h culture in the absence of MET; this blockage was not reversed by addition of HCY. ETH at the lC50 in MET-HCY+ medium blocked DNA replication. Apoptotic cells appeared after 30 h incubation in MET-HCY+ medium only when ETH was added. ATP pools were decreased after 15 h of culture in MET-free medium. In vivo, MET starvation was obtained by feeding tumour-bearing mice a diet containing a synthetic amino acid mixture as the protein supply, in which HCY replaced MET. Given to nude mice bearing xenografted PC-3, from day 1 after grafting and for 3 weeks, this diet inhibited tumour growth (34% on day 20, P < 0.007); this effect was potentiated by ETH (200 mg kg-' day-' i.p.) (56% on day 20, P < 5 x 1 0-5). The differences between the effects of these two treatments were significant (P < 0.017) and optimal on day 20. These data showed that combination of ETH and HCY slowed the proliferation of prostate cancer cells in vitro and in vivo, decreased ATP synthesis and caused cell cycle arrest and apoptosis. Experimental therapy based on cancer cell MET metabolism deficiency could be efficient for treating advanced prostate cancers refractory to current therapies.

S-adenosylmethionine limitation induces p38 mitogen activated protein kinase and triggers cell cycle arrest in G1

“…Methionine stress hypersensitivity is an almost universal metabolic characteristic of cancer cells and tumors (Guo et al, 1993;Kreis, 1979;Mecham et al, 1983;Poirson-Bichat et al, 1997;Stern et al, 1984;Tisdale et al, 1983) and was recently suggested to reflect a hypersensitive SAM checkpoint in cancer cells (Booher et al, 2012). Therefore, further understanding of the pathways connecting levels of SAM with cell proliferation will provide molecular insight into integration of metabolite homeostasis with cell cycle regulation and might lead to discovery of new cancer drug targets.…”

Methionine-dependence and combination chemotherapy on human gastric cancer cellsin vitro

“…Up to now, quite a few studies have elucidated the property of methionine (Met) dependence of cancer cells [31][32][33][34] . If that property was utilized in combination with specific chemotherapeutic drugs, the proliferation of tumor cells would be suppressed.…”

Influence of L-methionine-deprived total parenteral nutrition with 5-fluorouracil on gastric cancer and host metabolism

“…However, normal cells can grow well in that medium. It means that the growth of tumor cell is Met-dependent [1][2][3][4][5][6][7][8][9] . In this study, we prepared a Met-free amino acid solution and used it as the sole nitrogen source of total parental nutrition (TPN), to investigate the influence of Met-deprived TPN on the gastric cancer and host metabolism.…”