Bioactivity and molecular targets of novel substituted quinolines in murine and human tumor cell lines in vitro

Abstract

Abstract. Substituted quinolines (PQ code number), which reduce colony formation and increase gap junctional intercellular communication, were tested for their ability to interact with various molecular targets in murine and human tumor cell lines in vitro. Various markers of tumor cell metabolism, DNA fragmentation, mitotic disruption, apoptosis induction and growth factor receptor signaling pathways were assayed in vitro to evaluate drug cytotoxicity. Based on its ability to inhibit the metabolic activity of suspension cultures of leukemic L1210 cells at days 2 and 4 in vitro, PQ1 succinic acid salt is the most effective antiproliferative agent among the synthetic quinoline analogs tested. Moreover, antiproliferative PQ1 is effective across a spectrum of monolayer cultures of pancreatic Pan02, epidermoid A-431 and mammary SK-BR-3 and BT-474 tumor cells. PQ1 also blocks Ki-67 expression, a marker of tumor cell proliferation. A 1.5-to 3-h treatment with PQ1 is sufficient to inhibit the incorporations of [ 3 H]-thymidine into DNA, [3 H]-uridine into RNA and [ 3 H]-leucine into protein used to assess the rates of macromolecule syntheses over a 0.5-or 1-h period of pulse-labeling in L1210 tumor cells. A 15-min pretreatment with PQ1 inhibits the cellular transport of both purine and pyrimidine nucleosides over a 30-sec period in vitro, suggesting that PQ1 may prevent the incorporation of [ 3 H]-adenosine and [ 3 H]-thymidine into DNA because it rapidly blocks the uptake of these nucleosides by the tumor cells. Since PQ1 does not reduce the fluorescence of the ethidium bromide-DNA complex, it does not directly bind to or destabilize double-stranded DNA.Over a 6-to -48-h period, PQ1 has very little effect on the mitotic index of L1210 cells but stimulates the formation of many binucleated cells and a few micronuclei, suggesting that this compound might increase mitotic abnormality, induce chromosomal damage or missegregation, and block cytokinesis. The fact that PQ1 induces initiator caspase-2 and effector caspase-3 activities and poly(ADP-ribose) polymerase-1 cleavage within 1-4 h and internucleosomal DNA fragmentation within 24 h in L1210 cells suggests that this antitumor drug can trigger the early and late events required for cells to undergo apotosis. Whole-cell immunodetection and Western blot analysis indicate that, in contrast to 17-(allylamino)-17-demethoxygeldanamycin and radicicol, PQ1 fails to down-regulate the protein level at 24 h and autophosphorylation at 3 h of membrane-anchored HER1 in A-431 cells and HER2 in SK-BR-3 cells, suggesting that this antitumor compound is unlikely to interact with and inhibit Hsp90 and the epidermal growth factor (EGF) receptor signaling pathways. In conclusion, antiproliferative PQ1 is effective against a spectrum of tumor cells and might interact with various membrane and nuclear targets to enhance gap junctions, inhibit nucleoside transport and block cytokinesis but does not appear to disrupt the EGF receptor-mediated signaling pathways to induce growth arrest and apopt...

The role of individual caspases in cell death induction by taxanes in breast cancer cells

“…It is known that functional p53 is absent in SK-BR-3 cells but present in MCF-7 cells. On the other hand, SK-BR-3 cells are known to have functional caspase-3 while MCF-7 cells are deficient in functional caspase-3 [ 32 , 33 ]. Such differences in proteins involved in apoptosis facilitated elucidation of the role of individual caspases in taxane-induced cell death.…”

Inhibition of breast cancer xenografts in a mouse model and the induction of apoptosis in multiple breast cancer cell lines by lactoferricin B peptide

“…SKBR3>MDA-MB-468>MCF7>MDA-MB-231. 27 The SKBR3 cells, which lack functional p53, but have functional caspase-3 were the most sensitive to the drugs used in the present study. In contrast, the MCF7 cells which have functional p53, but not functional caspase-3, were relatively resistant.…”

“…The MCF7 cell line is luminal A type and the SKBR3 cell line is Her2‐positive; the two triple‐negative cell lines, MDA‐MB‐468 and MDA‐MB‐231, are basal type and Claudin‐low type, respectively 25,26 . Chemotherapeutic drugs targeting Her2 have exhibited a sensitivity ranking in breast cancer cell lines as follows: SKBR3>MDA‐MB‐468>MCF7>MDA‐MB‐231 27 . The SKBR3 cells, which lack functional p53, but have functional caspase‐3 were the most sensitive to the drugs used in the present study.…”