Influence on antiproliferative activity of structural modification and conjugation of gonadotropin-releasing hormone (GnRH) analogues.

The effect of various GnRH analogues, and their conjugates on proliferation, clonogenicity and cell cycle phase distribution of MCF-7 and Ishikawa human cancer cell lines was studied. GnRH-III, a sea lamprey GnRH analogue reduced cell proliferation by 35% and clonogenicity by 55%. Structural modifications either decreased, or did not alter biological activity.

Effects of methylacetylenic putrescine, an ornithine decarboxylase inhibitor and potential novel anticancer agent, on human and mouse cancer cell lines.

Sensitivity of several human and mouse cancer cell lines to methylacetylenic putrescine (MAP) was evaluated using clonogenic, sulforhodamine B and cell counting assays. The effects of MAP on cell morphology, cell cycle phase distribution and changes in polyamine metabolism of xenografted MCF-7 and MDA-MB-231 human mammary tumor cells were also investigated. On the basis of IC50 values, BHT-101 human thyroid carcinoma cells were the most sensitive (9 micrograms/ml), followed by P388 mouse lymphoma (32 micrograms/ml), MCF-7 (48 micrograms/ml) and MDA-MB-231 (110 micrograms/ml) human breast carcinoma cell lines.

Gonadotropin-releasing hormone analogue conjugates with strong selective antitumor activity.

Conjugation of gonadotropin-releasing hormone (GnRH) analogues GnRH-III, MI-1544, and MI-1892 through lysyl side chains and a tetrapeptide spacer, Gly-Phe-Leu-Gly (X) to a copolymer, poly(N-vinylpyrrolidone-co-maleic acid) (P) caused increased antiproliferative activity toward MCF-7 and MDA-MB-231 breast, PC3 and LNCaP prostate, and Ishikawa endometrial cancer cell lines in culture and against tumor development by xenografts of the breast cancer cells in immunodeficient mice. MCF-7 cells treated with P-X-1544 and P-X-1892 displayed characteristic signs of apoptosis, including vacuoles in the cytoplasm, rounding up, apoptotic bodies, bleb formation, and DNA fragmentation. Conjugates, but not free peptides, inhibited cdc25 phosphatase and caused accumulation of Ishikawa and PC3 cells in the G2/M phase of the cell cycle after 24 h at lower doses and in the G1 and G2 phases after 48 h.

Direct anticancer activity of gonadotropin-releasing hormone-III.

In previous studies GnRH-III, a variant of the hypothalamic neurohormone GnRH, was isolated from the brain of the sea lamprey and structurally characterized. GnRH-III is a hypothalamic neurohormone in both female and male sea lampreys. In the present work biological activities of GnRH-III in mammalian systems were examined.

Synthesis of gonadotropin-releasing hormone III analogs. Structure-antitumor activity relationships.

Following the observation that the activity of gonadotropin-releasing hormone III (GnRH-III) in the suppression of growth of MDA-MB-231 and MCF-7 breast cancer cells surpasses that of GnRH and other analogs thereof, analogs of GnRH-III were synthesized to investigate the structural basis for the improved antitumor activity. Compounds synthesized include analogs with changes in the central sequence in which GnRH-III differs from GnRH and in the C- and N-terminal regions. The results indicate that a salt bridge between Asp6 and Lys8 stabilizes the active conformation of GnRH-III and show the importance of the Trp7.

Synthesis, conformation, biodistribution, and hormone-related in vitro antitumor activity of a gonadotropin-releasing hormone antagonist-branched polypeptide conjugate.

Since permanently high levels of GnRH analogues are necessary to exert direct and/or indirect antitumor effect on mammary tumors, much emphasis was put on the development of retarded-release devices (e.g. microcapsules) for GnRH derivatives.

Synthesis of GnRH analogs having direct antitumor and low LH-releasing activity.

New chicken I GnRH agonists and antagonists have been synthesized and tested for their biological activities. The common feature of these analogs was that the molecules had a beta-L-aspartyl residue inserted in position 6. The agonist bound to the pituitary still had low endocrinological activity.

In vivo studies of the new gonadotropin-releasing hormone antagonist--copolymer conjugates having antitumor activity.

The aim of the study was to test in vivo the gonadotropin-releasing hormone (GnRH) antagonists and their conjugates showing antitumor activities in vitro. The in vivo experiments with the human GnRH antagonist MI-1544 (Ac-D-Trp1,3,D-Cpa2,D-Lys6,D-Ala10)-GnRH, the chicken GnRH antagonist MI-1892 (Ac-D-Trp1,3,D-Cpa2,Lys5,/beta-Asp(DEA)/6,Gln8,D-Al a10)-GnRH, and their copolymer conjugates were carried out on MCF-7 and MDA-MB-231 human breast tumors xenografted in immunosuppressed CBA/Ca HRIJ-T6 female mice and on MXT mouse mammary tumors in BDF1 mice. The P-X-1544 and P-X-1892 conjugates were prepared by coupling the GnRH antagonists to macromolecule copolymer through biodegradable spacers.

Effect of gonadotropin-releasing hormone analogs and their conjugates on gonadotropin-releasing hormone receptor--positive human cancer cell lines.

The purpose of the present investigation was to develop new gonadotropin-releasing hormone (GnRH) antagonists and to increase their stability and antitumor effect by conjugation with carrier macromolecules. Antitumor effect was evaluated using clonogenic assay, cell counting for antiproliferation, and sulforhodamine B method. The presence of GnRH-binding sites in human cancer cell lines (MCF-7, MDA-MB-231, Ishikawa, LNCaP) was proved.

Establishment and characterization of an EBNA-negative human lymphoma cell line (BHL-89).

Background: The aim of the work was to establish human malignant lymphomas in culture, in order to study the biological characteristics and drug sensitivity of lymphomas of human lymphoid origin.

Materials And Methods: Lymph nodes of patients were explanted and kept in cultures using conventional tissue culture methods. Cytogenetic methods were used for karyotype analysis.

Antitumour effect of a gonadotropin-releasing-hormone antagonist (MI-1544) and its conjugate on human breast cancer cells and their xenografts.

Our gonadotropin-releasing hormone (GnRH) antagonist analogue MI-1544 ([Ac-D-Trp1,3,D-Cpa2,D-Lys6,D-Ala10]GnRH) was developed as a potential contraceptive material, because it decreased the luteinizing hormone level without unfavourable side-effects. The antagonist was covalently bound to poly[Lys-(Ac-Glu0.96-DL-Ala3.

Dominant expression of multidrug resistance in intraspecific murine lymphoma hybrid cells.

Cultured P388/VCR mouse lymphoma cells resistant to vincristine (VCR) and to 5-bromodeoxyuridine (BUdR) and deficient in thymidine kinase (TK-) were fused with P388/DAG cells resistant to 1.2:5,6-dianhydrogalactitol (DAG), an anticancer alkylating agent, and to 6-thioguanine (6-TG) and deficient in hypoxanthine phosphoribosyl-transferase (HPRT-). The hybrid cells expressed multidrug resistance (MDR), i.

Establishment, characterization and drug sensitivity of a new anaplastic thyroid carcinoma cell line (BHT-101).

A thyroid carcinoma cell line, BHT-101, has been established in vitro from a metastatic lymph node deposit in a female patient with a non-hormone producing anaplastic, partly thyroglobulin- and thyroxine (T4)-positive papillary thyroid cancer. The cell population is heterogeneous, containing epithelial-like and fibroblast-like cells, and has a doubling time of 24 h. The cell line is polyploid with hypertetraploid predominance and the karyotype showed trisomies, tetrasomies, pentasomies as well as many marker chromosomes.

Benzamide potentiation of the cytotoxicity of bifunctional galactitol [correction of galacticol] in resistant P388 leukemia correlates with inhibition of DNA ligase II.

Benzamide (BA) enhances the cytotoxicity of 1,2:5,6-dianhydrogalactitol (DAG) in resistant P388 leukemia cell lines but not in the sensitive parent line. To examine the reason for this difference in response, we carried out an alkaline elution assay using proteinase K to study DNA interstrand cross-linking. At early time points, equal concentrations of DAG produced the same level of interstrand cross-linking (ICL) in the resistant and sensitive P388 leukemic cells, although marked differences were observed in their cytotoxicity toward the two cell lines.

Comparative studies on the polyamine metabolism and DFMO treatment of MCF-7 and MDA-MB-231 breast cancer cell lines and xenografts.

In order to characterize the estrogen receptor (ER)-positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells and xenografts, their growth kinetic parameters and some biochemical characteristics concerning the receptor status and polyamine metabolism were determined and compared. The doubling times calculated from the growth curves showed higher proliferation rate of MDA-MB-231 cells, both in culture (21 hours) and in xenograft (9.7 days), in comparison to the MCF-7 cells which had values of 32 hours and 11.

Influence of luteinizing hormone-releasing hormone agonists on human mammary carcinoma cell lines and their xenografts.

The specific binding of luteinizing hormone-releasing hormone (LH-RH) agonist in estradiol-dependent MCF-7 and estradiol-independent MDA-MB-231 human breast cancer cells has been studied using [3H]Ovurelin [(D-3H-Phe6),des-Gly10-LH-RH- ethylamide]. The results of Scatchard analyses suggest the presence of a single class of receptor sites, both in cell suspensions and membrane fractions. Evaluation of these peptide receptors appears to reflect additional characteristics of biological behaviour of these human breast cancer cells.

Genotypic and phenotypic changes of a mouse lymphoma during long-term cultivation.

NK/Ly mouse lymphoma ascites cells were explanted and established in culture. The cells grew in monolayer and showed fibroblast-like morphology. The original NK/Ly cells contained one large metacentric marker chromosome, while the in vitro growing cells had two metacentrics in the early passages.

Dominance of resistance to the alkylating agent 1,2:5,6-dianhydrogalactitol in P388 mouse lymphoma hybrid cells.

Cultured P388/S mouse lymphoma cells resistant to 5-bromodeoxyuridine (BUdR) and deficient in thymidine kinase (TK-) were fused with P388/DAG cells resistant to 1,2:5,6-dianhydrogalactitol (DAG), an anticancer alkylating agent, and to 6-thioguanine (6-TG) and deficient in hypoxanthine phosphoribosyl-transferase (HPRT-). Sensitivity to DAG in the hybrid line was very close to that in the P388/DAG line, which means that resistance to DAG was inherited in a quasi-dominant manner. Hybrid cells showed cross-resistance, similar to that of the DAG-resistant line, to two other hexitols, dibromodulcitol (DBD) and disuccinyldianhydrogalactitol (DisuDAG).

Heterogeneity of the response to inducers of differentiation and to cytostatics of tumor cell populations.

The purpose of the experiments was to establish whether individual cells of a tumor cell population, or clonal lines derived from its express the differentiated phenotype, or respond heterogeneously following treatment with inducers of differentiation or with cytostatic drugs. The human cell lines used in this study were: HL-60 promyelocytic leukemia, K562 erythroleukemia, BHM-97 and A2058 melanoma, and A-1, A-2, A-4 and A-6 clones of A2058 line. Inducers of differentiation were phorbol myristate acetate (PMA), dimethylsulfoxide (DMSO) and retinoic acid (RA); cytostatics: adriamycin (ADM), 5-fluorouracil (5-FU), dacarbazine (DTIC), cis-platin (platidiam, PD) and arabinosyl cytosine (ara-C).

Changes in the polyamine and nucleotide metabolism of P388 leukemia cells treated with DL-alpha-difluoromethylornithine in culture.

Influence of DL-alpha-difluoromethylornithine (DFMO) treatment on the growth kinetics, labelling index, extra- and intracellular polyamine and nucleotide concentrations was monitored in cultured P388 leukemia cells. A substantial decrease of cell proliferation was observed when the cells were continuously treated with 1-5 mM DFMO. Depletion of cellular polyamines, mostly of putrescine and spermidine, was seen with a concomitant but delayed increase of spermidine and spermine levels in the culture medium.

Survival responses to new cytostatic hexitols of P388 mouse and K562 human leukemia cells in vitro.

The effects of four hexitol compounds [mitolactol, dianhydrogalactitol, 3,4-diacetyldianhydrogalactitol (DiacDAG), and 3,4-disuccinyldianhydrogalactitol]; two vinca alkaloids (vincristine and N-formylleurosine); doxorubicin; and methotrexate on colony formation of P388 and K562 cells were studied and compared. DisuDAG is a new derivative of hexitols with favorable therapeutic indices on rodent tumors. On the basis of IC50 values in molar concentrations, dianhydrogalactitol was five to six times more toxic than DiacDAG, and mitolactol was 36 (K562) or 80 (P388) times more toxic than DisuDAG.

The effect of N-formylleurosine on DNA synthesis of Ehrlich ascites tumor.

Some of the vinca alkaloids are well known and widely used in clinical practice, in spite of their numerous side-effects. For the elimination of untoward side-effects semi-synthetic alkaloids have been produced. This work reports on N-formylleurosine (N-F-Leu), one of these agents.

Effect of low-output He-Ne laser rays on the colony-forming ability of the cells of mice lymphoma.

The effect of low-output He-Ne laser rays on the survival of mouse lymphoma P388 cell cultures was studied on the basis of the colony forming ability. Irradiation with 1.3 and 9 joule of 5 and 10 mW He-Ne lasers, respectively, seemed to cause a relatively low cell necrosis.