MK615 inhibits pancreatic cancer cell growth by dual inhibition of Aurora A and B kinases.

AIM: To investigate the anti-neoplastic effect of MK615, an anti-neoplastic compound isolated from Japanese apricot, against human pancreatic cancer cells in vitro. METHODS: Three human pancreatic cancer cell lines PANC-1, PK-1, and PK45H were cultured with MK615 at concentrations of 600, 300, 150, and 0 microg/mL. Growth inhibition was evaluated by cell proliferation assay, and killing activity was determined by lactate dehydrogenase (LDH) assay. Expression of Aurora A and B kinases was detected by real-time polymerase chain reaction (PCR) and Western blotting. Cell cycle stages were evaluated by flow cytometry. RESULTS: The growth inhibitory rates of MK615 at 150, 300, and 600 microg/mL were 2.3%+/-0.9%, 8.9%+/-3.2% and 67.1%+/-8.1% on PANC1 cells, 1.3%+/-0.3%, 8.7%+/-4.1% and 45.7+/-7.6% on PK1 cells, and 1.2+/-0.8%, 9.1%+/-2.1% and 52.1%+/-5.5% on PK45H cells, respectively (P<0.05). The percentage cytotoxicities of MK615 at 0, 150, 300, and 600 microg/mL were 19.6%+/-1.3%, 26.7%+/-1.8%, 25.5%+/-0.9% and 26.4%+/-0.9% in PANC1 cells, 19.7%+/-1.3%, 24.7%+/-0.8%, 25.9%+/-0.9% and 29.9%+/-1.1% in PK1 cells, and 28.0%+/-0.9%, 31.2%+/-0.9%, 30.4%+/-1.1% and 35.3+/-1.0% in PK45H cells, respectively (P<0.05). Real-time PCR and Western blotting showed that MK615 dually inhibited the expression of Aurora A and B kinases. Cell cycle analysis revealed that MK615 increased the population of cells in G2/M phase. CONCLUSION: MK615 exerts an anti-neoplastic effect on human pancreatic cancer cells in vitro by dual inhibition of Aurora A and B kinases.

A novel anti-cancer substance, MK615, from ume, a variety of Japanese apricot, inhibits growth of hepatocellular carcinoma cells by suppressing Aurora A kinase activity.

BACKGROUND/AIMS: MK615 is an anti-cancer substance extracted from the Japanese apricot. In the present study, the anti-neoplastic effect of MK615 against hepatocellular carcinoma (HCC) was evaluated in vitro, and its mechanism was elucidated. METHODOLOGY: Two HCC lines, HuH7 and Hep3B, were cultured with MK615 at concentrations of 600, 300, 150, and 0 microg/mL. Growth inhibition was evaluated by MTT assay, and killing activity was determined by LDH assay. Cell cycle stages were evaluated by flow cytometry. Expression of Aurora A kinase (Aurora A) was evaluated by real-time PCR and Western blotting, and inhibition of Aurora A activity was determined by HTscan. RESULTS: MK615 inhibited the growth of, and lysed, HuH7 and Hep3B cells in a dose-dependent manner. Cell cycle analysis revealed that MK615 increased the population of cells in G2/M phase. Real-time PCR and Western blotting showed that MK615 suppressed the expression of Aurora A. HTscan assay demonstrated that Aurora A activity was specifically inhibited by 34.3%, 32.9%, and 54.3% at 150, 300, and 600 microg/mL MK615, respectively. CONCLUSIONS: MK615 has an anti-cancer effect against HCC lines in vitro, and the effect is exerted through inhibition of Aurora A activity.

Antineoplastic effect of a single oral dose of the novel Flt3 inhibitor KRN383 on xenografted human leukemic cells harboring Flt3-activating mutations.

Activating mutations of Fms-like tyrosine kinase 3 (Flt3) are the most common genetic abnormalities found in acute myeloid leukemia (AML) and represent potential therapeutic targets. The novel Flt3 inhibitor KRN383 inhibited the autophosphorylation of Flt3 bearing internal tandem duplications (ITDs) and the Asp835Tyr (D835Y) point mutation with half-maximal inhibitory concentration (IC(50)) values of < or =5.9 and 43 nM, respectively. KRN383 also inhibited the proliferation of the ITD-positive cell lines with IC(50) values of < or =2.9 nM. A single oral administration of 80 mg/kg of KRN383 eradicated ITD-positive xenograft tumors in nude mice and prolonged the survival of SCID mice carrying ITD-positive AML cells. The effectiveness of a single oral dose of KRN383 suggests that it has the potential to be used in a wide variety of clinical regimens, including multicycle and combination therapies.

Identification of potent and selective inhibitors of PDGF receptor autophosphorylation.

We report the structure-activity relationship of quinoline and quinazoline derivatives, which include urea, thiourea, urethane, and acylthiourea groups, as inhibitors of the platelet-derived growth factor (PDGF) receptor autophosphorylation. Our previous studies showed that the quinoline and quinazoline derivatives including urea, thiourea, and carbamate groups were highly potent compounds as the PDGF receptor autophosphorylation inhibitor, but these compounds did not exhibit receptor selectivity between the PDGF receptor and the c-kit receptor. As a result of further synthesis and biological evaluation, we have found that the quinoline and quinazoline-acylthiourea derivatives showed not only good inhibitory activity for the PDGF receptor but also receptor selectivity between the PDGF receptor and the c-kit receptor. Furthermore N-{4-[(6,7-dimethoxy-4-quinolyl)oxy]phenyl}-N'-(2-methylbenzoyl)thiourea exhibited potent oral efficacy in in vivo assay using the rat carotid balloon injury model. Therefore, the quinoline and quinazoline-acylthiourea derivatives may be expected to have potential as therapeutic agents for the treatment of restenosis.

Orally active anti-proliferation agents: novel diphenylamine derivatives as FGF-R2 autophosphorylation inhibitors.

(6,7-Disubstituted-quinolin-4-yloxy-phenyl)(4-substituted-phenyl)amine derivatives were synthesized and evaluated by a cellular autophosphorylation assay for FGF-R2 in the human scirrhous gastric carcinoma cell line, OCUM-2MD3. We also performed metabolic stability studies showing that substitutions at the 7-position of quinoline affect its biological stability. In this study, we achieved a remarkable improvement in the solubility and metabolic stability of the diphenylamine derivative. The most promising compound 15e showed a significant decrease in tumor volume when orally administered.

Synthesis and structure-activity relationship for new series of 4-phenoxyquinoline derivatives as specific inhibitors of platelet-derived growth factor receptor tyrosine kinase.

We discovered a new series of 4-phenoxyquinoline derivatives as potent and selective inhibitors of the platelet-derived growth factor receptor (PDGFr) tyrosine kinase. We researched the highly potent and selective inhibitors on the basis of both PDGFr and epidermal growth factor receptor (EGFr) inhibitory activity. First, we found a compound, Ki6783 (1), which inhibited PDGFr autophosphorylation at 0.13 microM, but it did not inhibit EGFr autophosphorylation at 100 microM. After extensive explorations, we found the two desired compounds, Ki6896 (2) and Ki6945 (3), which are substituted by benzoyl and benzamide at the 4-position of the phenoxy group on 4-phenoxyquinoline, respectively. These inhibitory activities were 0.31 and 0.050 microM, respectively, but neither of them inhibited EGFr autophosphorylation at 100 microM. We further investigated the profile of both compounds toward various tyrosine and serine/threonine kinases. The three compounds specifically inhibited PDGFr rather than the other kinases.