harmine and Carcinoma--Hepatocellular

Topics: Antineoplastic Agents; Apoptosis; Carbolines; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Cinnamates; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Liver Neoplasms; Molecular Structure; Structure-Activity Relationship

To avoid cell cycle arrest or apoptosis, rapidly proliferating cancer cells have to promote DNA double strand break (DSB) repair to fix replication stress induced DSBs. Therefore, developing drugs blocking homologous recombination (HR) and nonhomologous end joining (NHEJ) - 2 major DSB repair pathways - holds great potential for cancer therapy. Over the last few decades, much attention has been paid to explore drugs targeting DSB repair pathways for cancer therapy. Here, using 2 well-established reporters for analyzing HR and NHEJ efficiency, we found that both HR and NHEJ are elevated in hepatoma cell lines Hep3B and HuH7 compared with normal liver cell lines Chang liver and QSG-7701. Our further study found that Harmine, a natural compound, negatively regulates HR but not NHEJ by interfering Rad51 recruitment, resulting in severe cytotoxicity in hepatoma cells. Furthermore, NHEJ inhibitor Nu7441 markedly sensitizes Hep3B cells to the anti-proliferative effects of Harmine. Taken together, our study suggested that Harmine holds great promise as an oncologic drug and combination of Harmine with a NHEJ inhibitor might be an effective strategy for anti-cancer treatment.

Topics: Antineoplastic Agents, Phytogenic; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Cell Survival; DNA Breaks, Double-Stranded; Drug Screening Assays, Antitumor; G2 Phase Cell Cycle Checkpoints; Harmine; Humans; Liver Neoplasms; Rad51 Recombinase; Recombinational DNA Repair; S Phase Cell Cycle Checkpoints

A novel mutagenic compound, 9-(4'-aminophenyl)-9H- pyrido[3,4-b]indole (aminophenylnorharman, APNH), is shown to be formed by the in vitro enzymatic reaction of 9H-pyrido[3,4-b]indole (norharman) and aniline. APNH generates DNA adducts (dG-C8-APNH), and is potently genotoxic to bacteria and mammalian cells. APNH has also been demonstrated to be formed in vivo from norharman and aniline, and suggested to be a new type of endogenous mutagenic compound. To determine its carcinogenic activity, long-term administration of APNH was investigated in 93 male and 90 female F344 rats. Rats were fed diets containing 0, 20 or 40 p.p.m. from 7 weeks of age. All animals were killed after 85 weeks treatment and necropsy was performed. Hepatocellular carcinomas (HCCs) were induced at incidences of 10 and 79% in male rats fed 20 and 40 p.p.m. APNH, and 34% in female rats fed 40 p.p.m. of APNH, respectively. In addition, colon adenocarcinomas were found at incidences of 3 and 9% in male rats, and 4 and 13% in female rats fed 20 and 40 p.p.m. of APNH, respectively. Other tumors, including thyroid carcinomas and mononuclear cell leukemia, were also seen in rats fed APNH. Polymerase chain reaction-single strand conformation polymorphism analysis revealed beta-catenin gene mutations in 24% of HCCs and K-ras, beta-catenin and Apc gene mutations were found in 22, 44 and 33% of colon cancers induced by APNH, respectively. Most mutations occurred at G:C base pairs. beta-Catenin protein accumulations in the nucleus and cytoplasm were also revealed in both liver and colon tumors. Thus, APNH induced liver and colon cancers with K-ras, beta-catenin and Apc gene mutations in F344 rats.

Topics: Adenocarcinoma; Aniline Compounds; Animals; beta Catenin; Carbolines; Carcinoma, Hepatocellular; Colon; Colonic Neoplasms; Cytoskeletal Proteins; Female; Genes, APC; Genes, ras; Harmine; Indoles; Leukemia; Liver; Liver Neoplasms; Male; Mutagens; Mutation; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Pyridines; Rats; Rats, Inbred F344; Thyroid Neoplasms; Trans-Activators

Transfected Madin-Darby canine kidney (MDCK) cells (of distal tubular origin) have been used to study transport of organic anions. These cells have not been shown to possess sulfate-conjugating activity. Neither has transport activity been demonstrated in nontransfected MDCK cells.. Polarized and monolayers of nontransfected MDCK type II cells were incubated with prototype substrates of phenolsulfotransferase (PST) and sodium sulfate in the absence or presence of known inhibitors of multidrug resistance protein (MRP): (3-3-(2-(7-chloro-2-quinionlinyl) ethenyl)phenyl)(3-dimethylamino-3-oxopropyl)thio)methyl)thio) propanoic acid (MK571), cyclosporin A (CsA), and probenecid. Effects of glutathione (GSH) and buthionine sulfoximine (BSO), potential modulators of the organic anion transporting protein/polypeptide (OATP) isoform, OATP1 were also examined. Sulfated conjugates were identified by high-performance liquid chromatography (HPLC)-radiometry or HPLC-fluorimetry.. Uptake, sulfate conjugation, and efflux of the sulfated conjugates of harmol, p-nitrophenol, N-acetyldopamine and acetaminophen were demonstrated. Activities in MDCK type II cells were higher than those in HepG2, human fetal liver, and Chang liver cells. A significant decrease in extracellular with a reciprocal increase in intracellular harmol sulfate was observed with MK571, CsA, and probenecid and with preloading of glutathione. Depletion of intracellular glutathione by BSO had the opposite effects.. Normal (nontransfected) MDCK type II cells provide a suitable system for the study of the physiologic processes of uptake, sulfate conjugation, and transport of sulfated conjugates in kidney cells. Based on the action of specific inhibitors and modulators of MRP2 and OATP1, it was concluded that MRP2-like and OATP1-like transporters are possibly responsible for the transport of sulfated conjugates.

Topics: Animals; Biological Transport; Buthionine Sulfoximine; Carcinoma, Hepatocellular; Cell Line, Tumor; Cyclosporine; Glutathione; Harmine; Humans; Immunosuppressive Agents; Kidney Tubules, Distal; Leukotriene Antagonists; Liver; Membrane Transport Proteins; Methotrexate; Multidrug Resistance-Associated Protein 2; Multidrug Resistance-Associated Proteins; Organic Anion Transport Protein 1; Probenecid; Propionates; Quinolines; Radiation-Protective Agents; Radiation-Sensitizing Agents; Sulfates; Uricosuric Agents