István Pályi

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

SummaryA 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. The majority of the cells are negative or weakly positive for thyroglobulin and thyroxine and estrogen and progesterone receptors are present in the cells. BHT-101 cells produce tumours when injected into immunosuppressed CBA/Ca mice. The cells are sensitive to adriamycin, methotrexate and tamoxifen but not to methimazole (Favistan). The epithelial-like clone 1 and the fibroblastlike clone 3, isolated from the parental line, differed in drug sensitivity. This new cell line is suitable for studying the biology of thyroid carcinoma and for parallel in vivo and in vitro studies of drug activity against thyroid cancer.

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-Ala3.1)] (AcEAK) —a branched polypeptide having a polylysine backbone — resulting in a MI-1544-AcEAK conjugate. According to our in vitro experiments the MI-1544 induced a 33%–35% decrease in cell numbers of MCF-7 and MDA-MB-231 human breast cancer cell lines at a dose of 30 μM. The biodegradable polymeric carrier, AcEAK, alone inhibited cell proliferation by only 13%–15%, while the MI-1544-AcEAK conjugate, applied at the same dose, was capable of producing 45%–50% inhibition of cell proliferation. Our in vivo experiments using immunosuppressed mice showed that MI-1544, applied twice daily s.c., inhibited the growth of oestrogensensitive and-insensitive xenografts by 65% and 30% respectively. This effect was potentiated (70%) in both types of xenografts by the presence of the polymeric carrier in the conjugate; however, the carrier by itself did not cause tumour growth inhibition. The polymeric polypeptide carrier is supposed to increase the stability of the GnRH antagonist and to prevent the rapid excretion of the covalently bound peptide molecule. The antagonist and its conjugate may have various direct and indirect effects on breast cancer cells and, as a consequence, the new GnRH antagonist conjugates are suitable for treating an extended range of breast cancers.

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. MAP treatment led to accumulation of P388 cells in G1 phase. At higher doses, the cytoplasm of the cells became vacuolated followed by apoptosis. The foamy cytoplasm may suggest a rare type of cell death (Clarke III type) called non-apoptotic programmed cell death. MAP treatment resulted in a total inhibition of ornithine decarboxylase (ODC) activity with a concomitant decrease of intracellular polyamine (mostly putrescine and spermidine) content in the breast cancer cells, whilst the spermine concentration was shown to increase. MAP proved at least 10 times more potent than the formerly studied DL-alpha-difluoromethylornithine making it an attractive candidate for clinical testing.

Synthesis of New Poly(N-Vinyl Pyrrolidone-Co-Maleic Acid) Peptide Hormone Conjugates with Anticancer Activity

Gonadotropin releasing hormone (GnRH) is a decapeptide regulating the gonadotropin release in organisms. Its analogues inhibit breast, endometrium and prostatic tumor cell proliferation in vitro. Some analogues were conjugated via the lysine side chain to poly(N-vinyl pyrrolidone-co-maleic acid) using biodegradable and non-biodegradable oligopeptide spacers. The conjugates were prepared by acylation of oligopeptide nitrophenyl esters with the polymeric precursor, poly(N-vinyl pyrrolidone-co-maleic anhydride), by reacting the GnRH analogues with the polymeric active ester. In vitro tests of these products exhibited increased effects on MCF-7 and MDA MB-231 breast, Ishikawa endometrium and PC3 prostatic human tumor cells compared with the parent decapeptides.

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.e., resistance to VCR and cross-resistance to Adriamycin (ADM) and actinomycin D (Act. D), in a dominant manner. The presence of glycoprotein p170, the MDR gene product, was detected in the hybrid cells. Resistance to DAG was also expressed dominantly, whereas cross-resistance to dibromodulcitol (DBD), a chemically related anticancer drug, was slight.