A novel intraperitoneal therapy for gastric cancer with DFP-10825, a unique RNAi therapeutic targeting thymidylate synthase, in a peritoneally disseminated xenograft model.

Purpose: In advanced gastric cancer, peritoneal dissemination is a life-threatening mode of metastasis. Since the treatment options with conventional chemotherapy remain limited, any novel therapeutic strategy that could control such metastasis would improve the outcome of treatment. We recently developed a unique RNA interference therapeutic regimen (DFP-10825) consisting of short hairpin RNA against thymidylate synthase (TS shRNA) and cationic liposomes.

A simplified method for manufacturing RNAi therapeutics for local administration.

RNA interference (RNAi) is one of the most promising strategies for cancer therapeutics. The successful translation of RNAi therapeutics to a clinic setting requires a delivery system that is efficient and simple to upscale. In this study, we devised a simple industrial method to manufacture lipoplex, which includes short hairpin RNA against the expression of thymidylate synthase (TS shRNA) - a key molecule for DNA biosynthesis.

Anticancer activity of the intraperitoneal-delivered DFP-10825, the cationic liposome-conjugated RNAi molecule targeting thymidylate synthase, on peritoneal disseminated ovarian cancer xenograft model.

Introduction: Peritoneal disseminated ovarian cancer is one of the most difficult cancers to treat with conventional anti-cancer drugs and the treatment options are very limited, although an intraperitoneal (ip) paclitaxel has shown some clinical benefit. Therefore, treatment of peritoneal disseminated ovarian cancer is a highly unmet medical need and it is urgent to develop a new ip delivered drug regulating the fast DNA synthesis.

Methods: We developed a unique RNAi molecule consisting of shRNA against the thymidylate synthase (TS) and a cationic liposome (DFP-10825) and tested its antitumor activity and PK profile in peritoneally disseminated human ovarian cancer ascites models by the luciferase gene-transfected SCID mice.

Analysis of the prolonged infusion of DFP-10917, a deoxycytidine analog, as a therapeutic strategy for the treatment of human tumor xenografts in vivo.

2'-C-cyano-2'-deoxy-1-β-D-arabino-pentofranocyl-cytosine (DFP-10917, CNDAC) is a 2'-deoxycytidine analog with antitumor activity against various tumor cells. However, a clinically available therapeutic regimen for this compound needs to be established and its functional mechanisms in relation to the dosing schedule need to be clarified. In this study, we evaluated the antitumor activity and toxicity of DFP-10917 by varying the dose and administration schedule in human solid tumor and leukemia xenografts in vivo.

Development of new promising antimetabolite, DFP-11207 with self-controlled toxicity in rodents.

To reduce 5-fluorouracil (5-FU)-induced serious toxicities without loss of antitumor activity, we have developed DFP-11207, a novel fluoropyrimidine, which consists of 1-ethoxymethyl-5-fluorouracil (EM-FU; a precursor form of 5-FU), 5-chloro-2,4-dihydroxypyridine (CDHP; an inhibitor of 5-FU degradation), and citrazinic acid (CTA; an inhibitor of 5-FU phosphorylation). In vitro studies of DFP-11207 indicated that it strongly inhibited the degradation of 5-FU by dihydropyrimidine dehydrogenase (DPD) in homogenates of the rat liver, and also inhibited the phosphorylation of 5-FU by orotate phosphoribosyltransferase (OPRT) in tumor tissues in a similar magnitude of potency by CDHP and CTA, respectively. Especially, DFP-11207 inhibited the intracellular phosphorylation of 5-FU in tumor cells in a dose-dependent manner whereas CTA alone did not protect intracellular 5-FU phosphorylation.

Role of the uridine/cytidine kinase 2 mutation in cellular sensitiveness toward 3'-ethynylcytidine treatment of human cancer cells.

A nucleosidic medicine, 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine [3'-ethynylcytidine (ECyd)], is a potent inhibitor of RNA polymerase I and shows anticancer activity to various human solid tumors in vitro and in vivo. ECyd is phosphorylated to 3'-ethyntlcytidine 5'-monophosphate by uridine/cytidine kinase 2 (UCK2) and subsequently further to diphosphate and triphosphate (3'-ethyntlcytidine 5'-diphosphate, 3'-ethyntlcytidine 5'-triphosphate). 3'-Ethyntlcytidine 5'-triphosphate is an active metabolite that can inhibit RNA polymerase I competitively, causing cancer cell death.

Co-administration of liposomal l-OHP and PEGylated TS shRNA-lipoplex: A novel approach to enhance anti-tumor efficacy and reduce the immunogenic response to RNAi molecules.

Many therapeutic strategies have been applied in efforts to conquer the development and/or progression of cancer. The combination of chemotherapy and an RNAi-based approach has proven to be an efficient anticancer therapy. However, the feasibility of such a therapeutic strategy has been substantially restricted either by the failure to achieve the efficient delivery of RNAi molecules to tumor tissue or by the immunostimulatory response triggered by RNAi molecules.

Metronomic S-1 dosing and thymidylate synthase silencing have synergistic antitumor efficacy in a colorectal cancer xenograft model.

Metronomic chemotherapy is currently considered an emerging therapeutic option in clinical oncology. S-1, an oral formulation of Tegafur (TF), a prodrug of 5-fluorouracil (5-FU), is designed to improve the antitumor activity of 5-FU in tandem with reducing its toxicity. Clinically, metronomic S-1 dosing has been approved for the standard first- and second-line treatment of metastatic or advanced stage of colorectal (CRC).

Downregulation of thymidylate synthase by RNAi molecules enhances the antitumor effect of pemetrexed in an orthotopic malignant mesothelioma xenograft mouse model.

Malignant pleural mesothelioma (MPM) is an incurable cancer with an increasing incidence. Currently, pemetrexed (PMX)-based chemotherapy is the mainstay of chemotherapy for MPM, however, the outcome of PMX-based chemotherapy in patients with MPM is dismal. RNA interference (RNAi) technology has been considered as an effective tool to substantially enhance the therapeutic efficacy of chemotherapeutic agents in many preclinical and clinical settings.

Association between mRNA expression of chemotherapy-related genes and clinicopathological features in colorectal cancer: A large-scale population analysis.

To establish the individualized treatment of patients with colorectal cancer, factors associated with chemotherapeutic effects should be identified. However, to the best of our knowledge, few studies are available on this topic, although it is known that the prognosis of patients and sensitivity to chemotherapy depend on the location of the tumor and that the tumor location is important for individualized treatment. In this study, primary tumors obtained from 1,129 patients with colorectal cancer were used to measure the mRNA expression levels of the following genes associated with the effects of standard chemotherapy for colorectal cancer: 5-fluorouracil (5-FU)-related thymidylate synthase (TYMS), dihydropyrimidine dehydrogenase (DPYD) and thymidine phosphorylase (TYMP); folate-related dihydrofolate reductase (DHFR), folylpolyglutamate synthase (FPGS) and gamma-glutamyl hydrolase (GGH); irinotecan-related topoisomerase I (TOP1); oxaliplatin-related excision repair cross-complementing 1 (ERCC1); biologic agent-related vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR).

Dynamic modulation of thymidylate synthase gene expression and fluorouracil sensitivity in human colorectal cancer cells.

Biomarkers have revolutionized cancer chemotherapy. However, many biomarker candidates are still in debate. In addition to clinical studies, a priori experimental approaches are needed.

The novel thymidylate synthase inhibitor trifluorothymidine (TFT) and TRAIL synergistically eradicate non-small cell lung cancer cells.

Purpose: TRAIL, a tumor selective anticancer agent, may be used for the treatment of non-small cell lung cancer (NSCLC). However, TRAIL resistance is frequently encountered. Here, the combined use of TRAIL with trifluorothymidine (TFT), a thymidylate synthase inhibitor, was examined for sensitizing NSCLC cells to TRAIL.

Effects of depletion of dihydropyrimidine dehydrogenase on focus formation and RPA phosphorylation.

Gimeracil, an inhibitor of dihydropyrimidine dehydrogenase (DPYD), partially inhibits homologous recombination (HR) repair and has a radiosensitizing effect as well as enhanced sensitivity to Camptothecin (CPT). DPYD is the target protein for radiosensitization by Gimeracil. We investigated the mechanisms of sensitization of radiation and CPT by DPYD inhibition using DLD-1 cells treated with siRNA for DPYD.

Role of miR-19b and its target mRNAs in 5-fluorouracil resistance in colon cancer cells.

Background: Drug resistance in colorectal cancers is assumed to be mediated by changes in the expression of microRNAs, but the specific identities and roles of microRNAs are largely unclear. We examined the effect of 5-fluorouracil (5-FU) resistance on microRNA expression.

Methods: Two types of 5-FU-resistant colon cancer cells were derived from the DLD-1 and KM12C cell lines.

Platelet-derived endothelial cell growth factor/thymidine phosphorylase inhibitor augments radiotherapeutic efficacy in experimental colorectal cancer.

Purposes: A lot of radiosensitizers have been developed. However, there are few to be available in the clinical setting. Thymidine phosphorylase inhibitor (TPI) regulates the phosphorolysis of thymidine to thymine and 2-deoxy-d-ribose-1-phosphate which is essential for tumor angiogenesis.

A nucleoside anticancer drug, 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (TAS106), sensitizes cells to radiation by suppressing BRCA2 expression.

Background: A novel anticancer drug 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (ECyd, TAS106) has been shown to radiosensitize tumor cells and to improve the therapeutic efficiency of X-irradiation. However, the effect of TAS106 on cellular DNA repair capacity has not been elucidated. Our aim in this study was to examine whether TAS106 modified the repair capacity of DNA double-strand breaks (DSBs) in tumor cells.

Gimeracil, an inhibitor of dihydropyrimidine dehydrogenase, inhibits the early step in homologous recombination.

Gimeracil (5-chloro-2, 4-dihydroxypyridine) is an inhibitor of dihydropyrimidine dehydrogenase (DPYD), which degrades pyrimidine including 5-fluorouracil in the blood. Gimeracil was originally added to an oral fluoropyrimidine derivative S-1 to yield prolonged 5-fluorouracil concentrations in serum and tumor tissues. We have already reported that gimeracil had radiosensitizing effects by partially inhibiting homologous recombination (HR) in the repair of DNA double strand breaks.

[Two woman medical doctors of the Meiji era who came from the "Preservative District of Johnai Suwakohji Important Traditional Buildings Group", Kanegasaki Town, Iwate Prefecture].

There is a historical group of samurai buildings called the "Preservative District of Johnai Suwakohji Important Traditional Buildings Group" in Kanegasaki Town, Iwate Prefecture. Two woman medical doctors (Misaho Aizawa and Mie Shiga, came from this district at the end of the Meiji Era (1910-1911). Misaho Aizawa was born in a minister's family in 1885 and studied at the Women's School of Dohshisha.

Trifluorothymidine exhibits potent antitumor activity via the induction of DNA double-strand breaks.

TAS-102 is an oral anticancer drug composed of trifluorothymidine (TFT) and TPI (an inhibitor of thymidine phosphorylase that strongly inhibits the biodegradation of TFT). Similar to 5-fluorouracil (5FU) and 5-fluoro-2'-deoxyuridine (FdUrd), TFT also inhibits thymidylate synthase (TS), a rate-limiting enzyme of DNA biosynthesis, and is incorporated into DNA. TFT exhibits an anticancer effect on colorectal cancer cells that have acquired 5FU and/or FdUrd resistance as a result of the overexpression of TS.

Mode of action of trifluorothymidine (TFT) against DNA replication and repair enzymes.

Trifluorothymidine (TFT) is well known to be converted to TFT-monophosphate by thymidine kinase and to inhibit thymidylate synthase. In addition, TFT-triphosphate (TFT-TP) is also incorporated into DNA, resulting in cytocidal effects. However, the precise mechanism of TFT-induced DNA damage is still unclear.

Total synthesis of the bicyclic marine sesquiterpenoid drechslerine B.

The total synthesis of the recently isolated bicyclic sesquiterpenoid drechslerine B (2), isolated from the algicolous fungus Drechslera dematioidearare in the marine red alga Liagora viscida, has been achieved, starting from (S)-carvone (8), via an intramolecular aldol reaction and palladium-catalyzed carbon monoxide insertion as key reactions.

In vivo evidence for a significant role of folylpolyglutamate synthase in combined chemotherapy with oral fluoropyrimidine, UFT or S-1, and leucovorin.

Combined chemotherapy with 5-fluorouracil and leucovorin (LV) has been widely used for the treatment of patients with colorectal cancer. Given that LV effects are attributable to increased levels of reduced folate in cancer cells, we attempted here to show the in vivo role of folylpolyglutamate synthetase (FPGS), which stabilizes intracellular reduced folate, in the anticancer activities of oral fluoropyrimidines, UFT or S-1, combined with LV. To this end, HCT-15 human colon cancer cells were knocked down for FPGS expression by RNA interference.

Establishment of a triple-negative type human breast cancer cell line that selectively metastasizes to the lung after orthotropic implantation.

Triple-negative type breast cancer (TNBC) is a challenge for today's clinical practice. To evaluate the efficacy of anticancer drugs and their combination for the treatment of patients with metastatic TNBC, an appropriate tumor model of metastatic TNBC is required. We developed a breast cancer model in mice that highly metastasizes to lung tissue using an established human TNBC cell line, MDA-MB-231.

Simple and rapid enzymatic method for the synthesis of single-strand oligonucleotides containing trifluorothymidine.

To investigate the mechanism of trifluorothymidine (TFT)-induced DNA damage, we developed an enzymatic method for the synthesis of single-strand oligonucleotides containing TFT-monophosphate residues. Sixteen-mer oligonucleotides and 14-mer 5'-phosphorylated oligonucleotides were annealed to the template of 25-mer, so as to empty one nucleotide site. TFT-triphosphate was incorporated into the site by DNA polymerase and then ligated to 5'-phosphorylated oligonucleotides by DNA ligase.