zhengguangmycin and Liver-Neoplasms

Using monoclonal antibody (mAb) Fab' fragment to develop mAb immunoconjugates for cancer.. Fab' fragment of mAb 3A5 was prepared by digestion of the antibody with pepsin and then reduced by dithiothreitol (DT), while Fab' fragment of mAb 3D6 was obtained by digestion of the antibody with ficin and subsequently reduced by beta-mercaptoethanol. The conjugation between Fab' fragment and pingyangmycin (PYM), an antitumor antibiotic, was mediated by dextran T-40. Immunoreactivity of Fab'-PYM conjugates with cancer cells was determined by ELISA, and the cytotoxicity of those conjugates to cancer cells was determined by clonogenic assay. Antitumor effects of the Fab'-PYM conjugates were evaluated by subcutaneously transplanted tumors in mice.. The molecular weight of Fab' fragment was approximately 53 kD, while the average molecular weight of Fab'-PYM conjugate was 170 kD. The Fab'-PYM conjugates showed immunoreactivity with antigen-relevant cancer cells and selective cytotoxicity against target cells. Administered intravenously, Fab'-PYM conjugates were more effective against the growth of tumors in mice than free PYM and PYM conjugated with intact mAb.. Fab'-PYM conjugate may be capable of targeting cancer cells and effectively inhibiting tumor growth, suggesting its therapeutic potential in cancer treatment.

Topics: Animals; Antibiotics, Antineoplastic; Antibodies, Monoclonal; Bleomycin; Carcinoma, Hepatocellular; Colonic Neoplasms; Female; HT29 Cells; Humans; Immunoglobulin Fab Fragments; Immunotoxins; KB Cells; Liver Neoplasms; Mice; Tumor Cells, Cultured

To develop an immunoconjugate with inhibitory effect on the growth of hepatoma and hepatic metastasis of tumor by linking Fab' fragment of monoclona antibody (McAb) to pingyangmycin (PYM).. Monoclonal antibody Fab' fragment was obtained by enzymolysis with pepsin and DTT reduction. Linking of the Fab' fragment and PYM was mediated by dextran T40. Indirect ELISA, TTC bacteriostatic titer test, clonogenic assay and animal models transplanted with tumor were used to assess the biological activities and antitumor effects of Fab' PYM conjugate within and without the bodies of 10 mice.. The Fab' PYM conjugate showed immunoreactivity to BEL7402, hepatoma 22 (H22) and HT29 cells, but no reaction to KB cells. The bacteriostatic activity of PYM in the conjugate was 15% as much as that of free PYM. The 50% inhibitory doses (IC50) of Fab'PYM conjugate to BEL7402, HT29 cells and KB cells were 0.02 micromol/L, 0.08 micromol/L and 0.50 micromol/L respectively. Given intravenously, 10 mg/kg x 6, Fab' PYM conjugate and PYM suppressed the growth of hepatoma 22 by 86% and 62% respectively. Given intraperitoneally, 10 mg/kg x 4, Fab' PYM and PYM decreased the hepatic metastasis of colon carcinoma 26 by 91% and 62% respectively.. Fab' PYM conjugate is more effective in combating hepatoma and hepatic metastasis of tumor than free PYM.

Topics: Animals; Antibodies, Monoclonal; Bleomycin; Carcinoma, Hepatocellular; Immunoconjugates; Immunoglobulin Fab Fragments; Liver Neoplasms; Mice; Mice, Inbred BALB C

Pingyangmycin (PYM), produced by Streptomyces pingyangensis n. sp., was found to be identical to bleomycin A5. In the present study, a comparative observation was carried out in 10 human cancer cell lines. As determined by a colony-forming assay, the dose-response curves obtained from cells exposed to PYM for 1 h were of one type only: biphasic exponential. The sensitivities of these cells derived from different types of tumors, however, varied with a broad range of ID50 values (0.03-0.82 microgram/ml). A hepatoma cell line (BEL-7402) and three lines derived from squamous carcinomas of the esophagus (Eca109 and CaEs17) or the nasopharynx (CNE) were relatively sensitive (ID50 less than 0.20 microgram/ml) to PYM which is known to have clinical activity against these diseases. Two gastric adenocarcinoma cell lines (MGc80-3 and BGC-823) and a pulmonary adenocarcinoma cell line (SPC-A-1) appeared to be less sensitive to the drug, with ID50 values of 0.21-0.47 microgram/ml. PYM was 7-fold more effective against LTEP-78 cells derived from pulmonary squamous carcinoma as opposed to SPC-A-1 cells, resulting in a low ID50 value of 0.04 microgram/ml. However, PYM as a single agent has not yet received full evaluation in relation to this type of lung cancer. In contrast with other cell lines of squamous cancer origin, HeLa and CC-801 cells derived from uterine cervix carcinomas which have been evaluated as highly responsive to PYM had the highest ID50 values (greater than 0.70 microgram/ml).

Topics: Adenocarcinoma; Antibiotics, Antineoplastic; Bleomycin; Carcinoma, Hepatocellular; Carcinoma, Squamous Cell; Esophageal Neoplasms; Female; Humans; Liver Neoplasms; Lung Neoplasms; Nasopharyngeal Neoplasms; Tumor Cells, Cultured; Tumor Stem Cell Assay; Uterine Cervical Neoplasms

Established human cancer cell lines derived from liver cancer (BEL-7402), nasopharyngeal cancer (CNE-2) and stomach cancer (MGC-803) were used in this study. These human cancer cells have been serially transplanted in nude mice. As determined by clonogenic assay, pingyangmycin (bleomycin A5) was highly cytotoxic to these three cell lines, of which the liver cancer cell line was more sensitive than the other two. At a tolerated dose level, pingyangmycin exhibited a remarkable growth inhibition on the growth of the liver cancer and stomach cancer xenografts, the inhibition rates being 70% and 85%, respectively. No pathologic changes were found in the organs of treated animals.

Topics: Adenocarcinoma, Mucinous; Animals; Antibiotics, Antineoplastic; Bleomycin; Carcinoma, Hepatocellular; Carcinoma, Squamous Cell; Cell Line; Female; Liver Neoplasms; Male; Mice; Mice, Nude; Nasopharyngeal Neoplasms; Neoplasm Transplantation; Stomach Neoplasms; Tumor Cells, Cultured