The first vitellogenin receptor from a Lepidopteran insect: molecular characterization, expression patterns and RNA interference analysis.

The vitellogenin receptor (VgR) belongs to the low-density lipoprotein receptor (LDLR) superfamily, and is an important carrier for the uptake of vitellogenin (Vg) into developing oocytes of all oviparous species. The first full-length message for a VgR from a Lepidopteran insect was cloned and sequenced from the ovary of Spodoptera litura Fabricius (GenBank accession no. GU983858). The coding region consisted of 5370 bp flanked by a 49 bp 5'-untranslated region (UTR) and a 177 bp 3'-UTR, which encoded a 1798-residue protein with a predicted molecular weight (MW) of 201.69 kDa. S. litura VgR (SlVgR)comprised two ligand binding sites with four LDLR class A repeats in the first domain and seven in the second domain, an epidermal growth factor-like domain containing an LDLR class B repeat and a YWXD motif, a transmembrane domain and a cytoplasmic domain. A phylogenetic relationship placed SlVgR as a separate group from the other insects. SlVgR messenger RNA (mRNA) was specifically expressed in the ovarian tissues. The developmental expression patterns showed that VgR mRNA was first transcribed in 6(th) day female pupae and the maximum level of VgR mRNA appeared in 36-h-old adults. Immunoblot analysis detected an ovary-specific VgR protein with a MW of ∼200 kDa, whose development profiles were consistent with VgR mRNA expression patterns. RNA inteference (RNAi) specifically disrupted the VgR gene by injection of 3 or 5 µg VgR double-stranded RNA per insect in 4(th) or 6(th) day pupae. RNAi of SlVgR led to a phenotype characterized by high Vg accumulation in the haemolymph, low Vg deposition in the ovary and the failure of insect spawning. These results mean that VgR is critical for binding Vg and transporting it into the oocytes of the insect ovary, thus playing an important role in insect reproduction.

Specific targeting of mitomycin C to tumors by anti-gastric cancer monoclonal antibody.

In the present study, an anti-gastric cancer monoclonal antibody, MGb2, was chosen to prepare antibody-mitomycin C (MMC) conjugate with dextran T-40 as intermediary. Twenty molecules of MMC were introduced into each molecule of antibody while the antigen-binding capacity of the antibody was kept well. The conjugate showed selective cytotoxicity upon human gastric cancer cell line SGC-7901. Radioimmunoimaging and biodistribution studies indicated that after conjugation with MMC via dextran T-40 as intermediary, the tumor localization capacity of the antibody was well retained. When tested in nude mice, inoculated with human gastric carcinoma SGC-7901 in bilateral subrenal capsules, intraperitoneal injection of the conjugate daily for 6 days at a dose of 1 mg/kg gave a tumor inhibitory rate of 68.67%, which was far better than that of free MMC or irrelevant conjugate. No synergetic effect was found in regard to the mixture of MGb2 with MMC.

[Effects of immuno-drug conjugates on growth of human gastric cancer xenograft in subrenal capsule of nude mice].

A conjugate of an anti-gastric cancer monoclonal antibody and mitomycin C linked by polyaldehyde dextran T-40 (MGb2-PAD-MMC) was prepared. Nude mice inoculated with human gastric cancer (SGC-7901) xenograft in bilateral subrenal capsule were treated ip with the conjugate at a daily dose containing MGb2 22.4 mg/kg and MMC 1 mg/kg for 6 d since 4 h after inoculation. The efficacy of the conjugate was estimated by the reduction of tumor size which calculated by T/C (%) was 32.2%. If MGb2 in the conjugate was replaced by a normal nude mice IgG (NIgG-PAD-MMC) or the nude mice were treated ip with the dose of MMC alone, the tumor T/C (%) were 58 and 87%, respectively. It was statistically significant between MGb2-PAD-MMC and NIgG-PAD-MMC or MMC treatment. When the above mentioned nude mice with SGC-7901 were treated ip with thrice dose of the conjugate (MGb2 67.2 mg/kg and MMC 3 mg/kg) for 6 d, the tumor growth was inhibited completely. Nevertheless, the same dose of MMC was given to the nude mice resulted in toxic appearance included anorexia, weight loss or even death. Furthermore, when the nude mice were treated ip with MGb2-PAD-MMC 24 h after inoculation, no apparent therapeutic effect was seen. In some experiments, nude mice inoculated with another human transplanted gastric tumor (GA II) xenograft treated ip with a conjugate of MGb2 and MMC or daunorubcin (Dau) 1 day after inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Preparation of antigastric cancer monoclonal antibody MGb2-mitomycin C conjugate with improved antitumor activity.

In the present study, an antigastric cancer monoclonal antibody, MGb2, was chosen to prepare antibody-mitomycin C conjugate with dextran T-40 as intermediary. Up to 20 molecules of mitomycin C were specifically bound per molecule of antibody, without significantly impairing the antigen-binding capacity of the antibody and the pharmacological activity of mitomycin C. The conjugate showed selective cytotoxicity upon human gastric cancer cell line SGC-7901 in vitro. Radioimmunoimaging and biodistribution studies indicated that, after conjugation with mitomycin C via dextran T-40 as intermediary, the tumor localization capacity of the antibody was well-retained. When tested in nude mice inoculated with human gastric carcinoma GAII in bilateral subrenal capsules, intraperitoneal injection of the conjugate twice a week for 3 weeks at the dose of 1 mg/kg of drug gave a tumor inhibitory rate of 152.29%, the result being far better than that of free mitomycin C or an irrelevant conjugate. A similar result was found in another nude mouse model of human gastric carcinoma SGC-7901. Meanwhile, after conjugation with antibody, the toxicity of mitomycin C on tested animals was significantly reduced.

[Therapeutic effects of 9 antitumor drugs on stomach adenocarcinoma (MKN-28) in nude mice].

Therapeutic effects of 9 antitumor drugs were studied on nude mice inoculated with transplanted human stomach tumor (MKN-28). When cisplatin, cyclophosphamide, chlormethine, 5-fluorouracil or mitomycin C was given ip to nude mice bearing MKN-28 at respective dose of 3, 100, 40, 80 and 2 mg/kg once weekly for 3 wk, the tumor inhibition rates of the former 3 drugs were over 80%, while the later 2 were 70-77%. Cytarabine 200 mg/kg twice or thrice weekly for 3 wk gave an inhibition rate of 68-72%. Hydroxycamptothecin 20 mg/kg twice weekly for 3 wk showed a better therapeutic effect than that given at 40 mg/kg once weekly for 3 wk, the tumor inhibition rates were 65 and 32% respectively. No apparent effect of vincristine and methotrexate on MKN-28 was seen. Histopathological observation indicated that in cisplatin group, numerous necrotic areas of tumor cells as well as sparse infiltration of inflammatory cells were found.

[Effects of 8 antitumor drugs against the growth of human lung adenocarcinoma (LAX-83) transplanted under the kidney capsule of nude mice].

Nude mice, inoculated with LAX 83 in bilateral subrenal capsules, were used in experimental therapy with 8 antitumor drugs. Treatment was initiated 2 d after tumor inoculation. All the drugs were ip to the nude mice daily for 7 d. At the daily doses VCR 0.4, MMC 2, CCNU 16, cis-DDP 2, AdM 2.5, 5-Fu 30, CTX 40 and MTX 2-6 mg/kg, the inhibition of the tumor growth were 100, 95.8, 91.3, 79.2, 65.2, 60.7, 62.3 and 0%, respectively. The results indicated that the effects of the drugs on nude mice inoculated with LAX-83 in subrenal capsule not only exhibited a good correlation to those in sc, but also shortened the period of experiment from 22 to 11 d. Furthermore, when LAX-83 was inoculated into the subrenal capsule of Swiss +/+ mice, the tumor tissues degenerated and disintegrated 2 d after the inoculation and replaced by inflammatory granuloma tissues 6 d later.

[The structure of glyuranolide, a new triterpene of Glycyrrhiza uralensis Fisch].

Using a medium pressure liquid chromatographic system, a new triterpene lactone named glyuranolide [3 beta, 22 alpha-dihydroxy-11-oxo-delta 12-oleanene-27 alpha-methoxy carbonyl-29-oic acid (29, 22 alpha-) lactone.] was isolated from the crude sapogenins of Glycyrrhiza uralensis Fisch. Its structure was elucidated by IR, UV, FAB-MS, and various NMR spectra (including NOE, BBD, INEPT, SR, COSY, NOESY etc.).

[Transplantation model of human lung oat cell carcinoma in nude mice].

A human lung oat cell carcinoma from a surgical specimen was successfully transplanted into nude mice and has been maintained for over four years through 14 passages. This transplanted tumor had a long latent period of more than one month, slowly growing in the initial inoculation and the following passages. The interval between two passages was about four months. 5 months after the inoculation, the transplanted tumor in nude mice grew to 2 cm in diameter. It was demonstrated that the transplanted tumor possessed the human isoenzyme pattern and human chromosome karyotype. The original human tumor and its transplanted counterparts in the nude mice were strikingly similar by histopathology. Besides, specific neuro-secretory granules in cytoplasm of the transplanted tumor were observed under transmission electron microscope.