Design and synthesis of novel thiazole-derivatives as potent ALK5 inhibitors.

TGF-ß is an immunosuppressive cytokine and plays a key role in progression of cancer by inducing immunosuppression in tumor microenvironment. Therefore, inhibition of TGF-ß signaling pathway may provide a potential therapeutic intervention in treating cancers. Herein, we report the discovery of a series of novel thiazole derivatives as potent inhibitors of ALK5, a serine-threonine kinase which is responsible for TGF-ß signal transduction. Compound 29b was identified as a potent inhibitor of ALK5 with an IC50 value of 3.7 nM with an excellent kinase selectivity.

Discovery of novel furanone derivatives as potent Cdc7 kinase inhibitors.

Cdc7 is a serine-threonine kinase and plays a conserved and important role in DNA replication, and it has been recognized as a potential anticancer target. Herein, we report the design, synthesis and structure-activity relationship of novel furanone derivatives as Cdc7 kinase inhibitors. Compound 13 was identified as a strong inhibitor of Cdc7 with an IC50 value of 0.6 nM in the presence of 1 mM ATP and showed excellent kinase selectivity. In addition, it exhibited slow off-rate characteristics, which may offer advantages over known Cdc7 inhibitors in its potential to yield prolonged inhibitory effects in vivo. Compound 13 potently inhibited Cdc7 activity in cancer cells, and effectively induced cell death.

Acquired resistance to miriplatin in rat hepatoma AH109A/MP10 is associated with increased Bcl-2 expression, leading to defects in inducing apoptosis.

Miriplatin, a novel lipophilic platinum complex approved to treat hepatocellular carcinoma, is administered into the hepatic artery after suspension in an oily contrast medium. Little is known concerning the mechanism of acquired resistance to miriplatin. In this study, we established and characterized a rat hepatoma cell subline, AH109A/MP10, which was about 10-fold more resistant to miriplatin than the parental cell line, AH109A. The established miriplatin-resistant cells showed clear cross-resistance to platinum complexes containing diaminocyclohexane as a carrier ligand, such as oxaliplatin and dichloro[(1R,2R)-1,2-cyclohexanediamine-N,N']platinum (DPC), while three human cancer cell lines selected for resistance to cisplatin (A2780cis, NCI-H69/CPR, MOR/CPR) did not show cross-resistance to miriplatin. There was no apparent difference in either intracellular platinum accumulation or platinum-DNA adducts in formation between resistant and parental cells after treatment with miriplatin or cisplatin, consisted with the unchanged expression of proteins involved in DNA repair, such as excision repair cross-complementing 1 (ERCC1) and mutL homolog 1 (MLH1). The increased expression of Bcl-2 was observed in AH109A/MP10 cells, in which apoptosis induced by miriplatin, but not cisplatin, was reduced. In addition, Bcl-2 inhibitor YC137 partially reversed the resistance of AH109A/MP10 cells to miriplatin. These findings suggested that the acquired resistance to miriplatin in AH109A/MP10 cells was associated in part with increased Bcl-2 expression, leading to defects in inducing apoptosis.

Intra-hepatic arterial administration with miriplatin suspended in an oily lymphographic agent inhibits the growth of tumors implanted in rat livers by inducing platinum-DNA adducts to form and massive apoptosis.

BACKGROUND: Miriplatin (formerly SM-11355), a novel lipophilic platinum complex developed to treat hepatocellular carcinoma, is administered into the hepatic artery using an oily lymphographic agent (Lipiodol Ultra-Fluide) as a carrier. We clarified the usefulness of miriplatin as an agent for transarterial chemoembolization. METHODS: Platinum compounds released from miriplatin into serum, medium and Earle's balanced salt solution were examined. Then, miriplatin and cisplatin were administered to rats bearing hepatoma AH109A tumors in livers. Platinum concentrations in tissues and DNA were assessed. RESULTS: Miriplatin showed a more sustained release than cisplatin. Dichloro[(1R, 2R)-1, 2-cyclohexane diamine-N, N']platinum, the most abundant platinum compound released from miriplatin, was as effective as cisplatin in inhibiting the growth of cells. Miriplatin was selectively disposed of in tumors, maintained in tumors longer than cisplatin and caused apparent tumor regression inducing platinum-DNA adducts to form and massive apoptosis. CONCLUSION: Miriplatin appears to be a suitable chemotherapeutic agent for transarterial chemoembolization.

Intra-hepatic arterial administration with miriplatin suspended in an oily lymphographic agent inhibits the growth of human hepatoma cells orthotopically implanted in nude rats.

Miriplatin is a lipophilic platinum complex which contains myristates as leaving groups and diaminocyclohexane as a carrier ligand. In order to examine in vivo the antitumor activities of miriplatin suspended in an oily lymphographic agent (Lipiodol Ultra-Fluide, LPD) against human hepatocellular carcinoma (HCC) after the intra-hepatic arterial administration, we have developed a novel orthotopic model of HCC in which the human hepatoma cell line Li-7 was successively implanted and maintained in the liver of nude rats. Li-7 tumors established in nude rat livers displayed a trabecular structure similar to their original morphology, and were exclusively supplied by the hepatic artery, suggesting that they exhibited in part the conditions of human HCC. Miriplatin suspended in LPD (miriplatin/LPD) administered into the hepatic artery of this model dose-dependently inhibited the growth of Li-7 tumors without markedly enhancing body weight loss and caused a significant reduction in the growth rate at a dose of 400 microg/head compared to LPD alone. In addition, at the therapeutic dose, miriplatin/LPD as well as cisplatin suspended in LPD (400 microg/head) was shown to be more active than zinostatin stimalamer suspended in LPD (20 microg/head) against Li-7 tumors after a single intra-hepatic arterial administration. These results suggest miriplatin to be a suitable candidate for use in transarterial chemoembolization.

Amrubicin induces apoptosis in human tumor cells mediated by the activation of caspase-3/7 preceding a loss of mitochondrial membrane potential.

Amrubicin, a completely synthetic 9-aminoanthracycline derivative, inhibits cell growth by stabilizing a topoisomerase II-DNA complex. This study was designed to examine the apoptosis induced in human leukemia U937 cells by amrubicin and its active metabolite amrubicinol. Amrubicin, amrubicinol and other antitumor agents, such as daunorubicin and etoposide, induced typical apoptosis with characteristic nuclear morphological change and DNA fragmentation. Measuring the population of sub-G(1) phase cells, it was found that under conditions where cell growth was inhibited by either amrubicin or amrubicinol, U937 cells underwent apoptotic cell death in a dose-dependent manner accompanied by an arrest of the cell cycle at G(2)/M. Furthermore, amrubicin- and amrubicinol-induced apoptosis was mediated by the activation of caspase-3/7, but not caspase-1, preceding a loss of mitochondrial membrane potential. These results indicate that both a reduction in mitochondrial membrane potential and the activation of caspase-3/7 are key events in the apoptosis induced by amrubicin and amrubicinol as well as the other antitumor agents. In addition, studies with oligomycin suggested that the apoptosis induced by amrubicin and amrubicinol involved substantially different pathways from that triggered by daunorubicin and etoposide. Oligomycin blocked the etoposide-induced increase in the number of sub-G(1) phase cells without preventing the activation of caspase-3/7, and had no inhibitory effect on the expansion of the sub-G(1) population in daunorubicin-treated cells, whereas apoptosis-related changes caused by amrubicin and amrubicinol were suppressed in the presence of oligomycin.

[Profile of the anti-tumor effects of amrubicin, a completely synthetic anthracycline].

Amrubicin is a completely synthetic anthracycline derivative. In contrast, however, the anthracyclines used clinically thus far have been produced by fermentation or semisynthesis. Amrubicin is structurally distinguishable from other anthracyclines by the amino group at the 9-position and its unique sugar moiety. Amrubicinol, the C-13 hydroxy- metabolite of amrubicin, is associated with a 5 to 200 times greater cytotoxicity than amrubicin. Amrubicin exhibited superior in vivo antitumor activity to doxorubicin in the human tumor xenograft model. Using this model, the level of amrubicinol (active metabolite) was shown to be higher than that of doxorubicin in tumor tissues, but lower in normal tissues. These results suggest potent therapeutic activity for amrubicin because of the selective distribution of its highly active metabolite, amrubicinol, in tumors. These anti-tumor effects of amrubicin are considered to be induced by DNA topoisomeraseII inhibition. In clinical studies, amrubicin has demonstrated potent single agent activity as compared to a standard regimen in untreated patients with extensive small cell lung cancer. Its major toxicity was myelosuppression (especially neutropenia).