Mitochondrial complex I inhibitors suppress tumor growth through concomitant acidification of the intra- and extracellular environment.

The disruption of the tumor microenvironment (TME) is a promising anti-cancer strategy, but its effective targeting for solid tumors remains unknown. Here, we investigated the anti-cancer activity of the mitochondrial complex I inhibitor intervenolin (ITV), which modulates the TME independent of energy depletion. By modulating lactate metabolism, ITV induced the concomitant acidification of the intra- and extracellular environment, which synergistically suppressed S6K1 activity in cancer cells through protein phosphatase-2A-mediated dephosphorylation via G-protein-coupled receptor(s).

Androprostamine A: a unique antiprostate cancer agent.

The androgen receptor (AR) is an important therapeutic target for all clinical states of prostate cancer. We screened cultured broths of microorganisms for their ability to suppress androgen-dependent growth of human prostate cancer LNCaP and VCaP cells without cytotoxicity. We have already identified androprostamine A (APA) from a Streptomyces culture broth as a functional inhibitor of AR.

Inhibition of mitochondria ATP synthase suppresses prostate cancer growth through reduced insulin-like growth factor-1 secretion by prostate stromal cells.

Modulation of prostate stromal cells (PrSCs) within tumor tissues is gaining attention for the treatment of solid tumors. Using our original in vitro coculture system, we previously reported that leucinostatin (LCS)-A, a peptide mycotoxin, inhibited prostate cancer DU-145 cell growth through reduction of insulin-like growth factor 1 (IGF-I) expression in PrSCs. To further obtain additional bioactive compounds from LCS-A, we designed and synthesized a series of LCS-A derivatives as compounds that target PrSCs.

Biological activity of intervenolin analogs with a phenyl substituent.

Intervenolin analogs with a phenyl substituent at the 2- or 3-position were synthesized. The compounds (3-11) showed weak or no inhibitory activity toward the growth of MKN-74 gastric adenocarcinoma cells, even in the presence or absence of the corresponding Hs738 stromal cells, whereas 2-substituted analogs exhibited selective anti-Helicobacter pylori activity. Introduction of a pendant side chain on the nitrogen alleviated their acute toxicity in mice.

Catalytic Asymmetric Total Synthesis and Stereochemical Revision of Leucinostatin A: A Modulator of Tumor-Stroma Interaction.

Total synthesis of leucinostatin A, a modulator of tumor-stroma interactions, using asymmetric catalyses, a nitroaldol reaction, thioamide-aldol reaction, Strecker-type reaction, and alcoholysis of 3-methylglutaric anhydride, is described. We demonstrated the applicability of the established catalytic asymmetric processes to the synthesis of molecules with a complex structure. Careful analysis of the NMR data, HPLC profiles, and biological activity revealed that the correct structure of leucinostatin A is the epimeric form of the reported structure; the secondary alcohol within the AHMOD residue has an R configuration.

Synthesis of Androprostamine A and Resormycin.

Syntheses of androprostamine A (1), and resormycin (3), anti-prostate cancer peptidyl natural products produced by microorganisms, were completed. The characteristic enamide structures of these compounds were installed using the Horner-Wadsworth-Emmons reaction from the corresponding phosphonates in reasonable Z-selectivity.

Synthesis and Structure-Activity Relationship Study of NBRI16716B, an Antitumor Natural Product.

The total synthesis of NBRI16716B (2), a naturally occurring modulator of tumor-stroma interactions, was successfully achieved. Using this synthetic route, a dehydroxy analogue (21) and a derivative lacking the 5-hydroxy-3-methylpentenoyl side chain (22) became accessible. A preliminary structure-activity relationship study to unveil the structural requirements for selective inhibition of tumor cells cocultured with stromal cells revealed that both of the hydroxamate structures of 2 are indispensable, whereas the 5-hydroxy-3-methylpentenoyl side chain is not essential.