Discovery of an Orally Efficacious MYC Inhibitor for Liver Cancer Using a GNMT-Based High-Throughput Screening System and Structure-Activity Relationship Analysis.

Glycine-N-methyl transferase (GNMT) downregulation results in spontaneous hepatocellular carcinoma (HCC). Overexpression of GNMT inhibits the proliferation of liver cancer cell lines and prevents carcinogen-induced HCC, suggesting that GNMT induction is a potential approach for anti-HCC therapy. Herein, we used Huh7 GNMT promoter-driven screening to identify a GNMT inducer. Compound K78 was identified and validated for its induction of GNMT and inhibition of Huh7 cell growth. Subsequently, we employed structure-activity relationship analysis and found a potent GNMT inducer, K117. K117 inhibited Huh7 cell growth in vitro and xenograft in vivo. Oral administration of a dosage of K117 at 10 mpk (milligrams per kilogram) can inhibit Huh7 xenograft in a manner equivalent to the effect of sorafenib at a dosage of 25 mpk. A mechanistic study revealed that K117 is an MYC inhibitor. Ectopic expression of MYC using CMV promoter blocked K117-mediated MYC inhibition and GNMT induction. Overall, K117 is a potential lead compound for HCC- and MYC-dependent cancers.

Chemical Constituents with GNMT-Promoter-Enhancing and NRF2-Reduction Activities from Taiwan Agarwood Excoecaria formosana.

Hepatocellular carcinoma (HCC) is considered to be a silent killer, and was the fourth leading global cause of cancer deaths in 2018. For now, sorafenib is the only approved drug for advanced HCC treatment. The introduction of additional chemopreventive agents and/or adjuvant therapies may be helpful for the treatment of HCC. After screening 3000 methanolic extracts from the Formosan plant extract bank, Excoecaria formosana showed glycine N-methyltransferase (GNMT)-promoter-enhancing and nuclear factor erythroid 2-related factor 2 (NRF2)-suppressing activities. Further, the investigation of the whole plant of E. formosana led to the isolation of a new steroid, 7α-hydroperoxysitosterol-3-O-ß-d-(6-O-palmitoyl)glucopyranoside (1); two new coumarinolignans, excoecoumarin A (2) and excoecoumarin B (3); a new diterpene, excoeterpenol A (4); and 40 known compounds (5-44). Among them, Compounds 38 and 40-44 at a 100 µM concentration showed a 2.97 ± 0.27-, 3.17 ± 1.03-, 2.73 ± 0.23-, 2.63 ± 0.14-, 6.57 ± 0.13-, and 2.62 ± 0.05-fold increase in GNMT promoter activity, respectively. In addition, Compounds 40 and 43 could reduce NRF2 activity, a transcription factor associated with drug resistance, in Huh7 cells with relative activity of 33.1 ± 0.2% and 45.2 ± 2.5%. These results provided the basis for the utilization of Taiwan agarwood for the development of anti-HCC agents.

Celecoxib enhances the therapeutic efficacy of epirubicin for Novikoff hepatoma in rats.

Epirubicin is a chemotherapy agent for hepatocellular carcinoma (HCC). However, the outcome of HCC patients receiving epirubicin remains unsatisfactory. Moreover, our previous study indicated that celecoxib suppresses HCC progression and liver cancer stemness. This study evaluated the potential of celecoxib to serve as a complementary therapy during epirubicin treatment. Cell proliferation, apoptosis, invasiveness, and anchorage-independent growth were analyzed in hepatoma cells. Therapeutic efficacy was validated in rat orthotopic Novikoff hepatoma. After animal sacrifice, the antitumor mechanism of celecoxib and epirubicin combined therapy was investigated by histological analysis. Celecoxib enhanced the cytotoxic activity of epirubicin in HCC cells by promoting apoptosis. Besides, celecoxib potentiated the antineoplastic function of epirubicin in inhibiting the invasiveness and anchorage-independent growth of HCC cells. Ultrasound monitoring showed that combined therapy was more potent than either therapy alone in perturbing HCC progression. Consistently, the size and weight of dissected HCC tissues from rats receiving combined therapy were smallest among all groups. HCC treated with combined therapy exhibited the highest prevalence of apoptotic cells, which was accompanied by reduced proliferating and angiogenic activities in tumor tissues. Moreover, the expression levels of cancer stemness markers (CD44 and CD133) and drug transporter MDR-1 were significantly diminished in rats receiving combined therapy. Besides, celecoxib treatment increased the infiltration of cytotoxic T lymphocytes (CTLs) and reduced the number of regulatory T cells (Tregs), tumor-associated macrophages (TAMs), and the expression of immune checkpoint PD-L1 in HCC tissues during epirubicin therapy. Celecoxib augmented the therapeutic efficacy while modulated cancer stemness and antitumor immunity. Thus, celecoxib may serve as complementary therapy to improve the outcome of patients with advanced HCC during epirubicin treatment.

Bioactive Triterpenoids from the Leaves and Twigs of Lithocarpus litseifolius and L. corneus.

Phytochemical investigation of the leaves and twigs of Lithocarpus litseifolius and Lithocarpus corneus resulted in the isolation of four new triterpenoids (1: -4: ), three triterpenoids (5: -7: ) isolated from a natural source for the first time, and six known compounds (8: -13: ). In addition, four known triterpenoids (14: -17: ) were isolated from L. corneus. Compound 1: is a 3,4-seco-lupane-type triterpenoid, and compounds 2: -4: are lupane-type triterpenoids in different oxidation states. The structures of all isolated compounds were identified by spectroscopic methods, especially NMR and mass spectrometry data. The absolute configuration of 2: and 3: was confirmed by X-ray single crystallographic analysis. The anti-inflammatory activities of 1: -17: and anti-HIV activities of 2: -17: were evaluated. Among them, 3-epi-betulinic acid (8: ) showed a strong anti-HIV activity comparable to abacavir, a drug used for treating HIV/AIDS. 3,4-seco-4(23),20(29)-lupadiene-3,28-dioic acid (5: ) exhibited potent inhibition of superoxide-anion generation with 86.9 ± 2.8% inhibition at 1 µM.

Identification of 1,2,3,4,6-Penta-O-galloyl-ß-d-glucopyranoside as a Glycine N-Methyltransferase Enhancer by High-Throughput Screening of Natural Products Inhibits Hepatocellular Carcinoma.

Glycine N-methyltransferase (GNMT) expression is vastly downregulated in hepatocellular carcinomas (HCC). High rates of GNMT knockout mice developed HCC, while overexpression of GNMT prevented aflatoxin-induced carcinogenicity and inhibited liver cancer cell proliferation. Therefore, in this study, we aimed for the identification of a GNMT inducer for HCC therapy. We established a GNMT promoter-driven luciferase reporter assay as a drug screening platform. Screening of 324 pure compounds and 480 crude extracts from Chinese medicinal herbs resulted in the identification of Paeonia lactiflora Pall (PL) extract and the active component 1,2,3,4,6-penta-O-galloyl-ß-d-glucopyranoside (PGG) as a GNMT inducer. Purified PL extract and PGG induced GNMT mRNA and protein expression in Huh7 human hepatoma cells and in xenograft tumors. PGG and PL extract had potent anti-HCC effects both in vitro and in vivo. Furthermore, PGG treatment induced apoptosis in Huh7 cells. Moreover, PGG treatment sensitized Huh7 cells to sorafenib treatment. Therefore, these results indicated that identifying a GNMT enhancer using the GNMT promoter-based assay might be a useful approach to find drugs for HCC. These data also suggested that PGG has therapeutic potential for the treatment of HCC.