Synergistic cytotoxic effects of zoledronic acid and radiation in human prostate cancer and myeloma cell lines

PURPOSE: The clinical use of the potent bisphosphonate zoledronic acid has increased recently, especially for the treatment of bone metastases. Synergistic effects with chemotherapeutic agents (e.g., doxorubicin, paclitaxel) have been shown. It is not known whether similar synergistic effects exist with radiation. METHODS AND MATERIALS: IM-9 myeloma cells and C4-2 prostate cancer cells were treated with up to 200 microM concentrations of zoledronic acid, irradiated with single doses of up to 1,000 cGy, or exposed to combinations of both treatments. Cell viability was then determined via yellow dye 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay and the affected fractions analyzed using the median effect principal, a method developed and validated by Chou and Talalay. RESULTS: A statistically significant synergistic cytotoxic effect of the combination of zoledronic acid and radiation was documented. The extent of the effect was cell type-dependent, with the C4-2 cells showing a greater synergistic effect than the IM-9 cells. CONCLUSIONS: The combined use of zoledronic acid and radiotherapy shows enhanced in vitro cytotoxicity for two human prostate and myeloma cancer cell lines over that expected for a simple additive effect from each treatment alone. A clinical trial is under way to test this combination therapy.     

托瑞米芬与化疗药物协同抑制肺癌A549细胞生长

目的：研究托瑞米芬对人肺腺癌细胞系A549的抑制作用及其与化疗药物联用的协同效应，以期为肺癌的临床治疗提供新的方向。方法：用MTT法检测不同浓度组药物对A549细胞的抑制作用。结果：托瑞米芬能直接抑制人肺腺癌A549细胞的生长，低剂量的托瑞米芬与化疗药物联用后的A值低于单用化疗药物组，其中与VCR、ADM、DDP、VP－16联用后的效果较好。结论：托瑞米芬与部分化疗药物联合应用对A549细胞系具有显著的协同抗肿瘤效应。这可能与肺癌的临床治疗提供实验依据。     

Anti-tumor promoting effects of multiflorane-type triterpenoids and cytotoxic activity of karounidiol against human cancer cell lines

Forty-nine multiflorane-type triterpenoids consisting of 11 compounds isolated from the seeds of Trichosanthes kirilowii (Cucurbitaceae) and 38 of their derivatives have been evaluated for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate in Raji cells as a primary screening test for anti-tumor promoters. All of the compounds tested showed an inhibitory effect against EBV-EA activation, and among which 43 were revealed to possess remarkable activity with potencies either comparable to or stronger than that of glycyrrhetic acid, a known natural anti-tumor promoter. Their structure-activity relationship is discussed. Evaluation of the cytotoxic activity of karounidiol (27) against human cancer cell lines exhibited cytotoxicity especially against a human renal cancer.     

Cytostatic and cytotoxic activity of synthetic genistein glycosides against human cancer cell lines

Genistein, the principal soy isoflavone, is a molecule of great interest as an innovative chemotherapeutic agent or as a lead-compound in anticancer drug design. To enhance intrinsic activity of genistein and to explore its pharmacophoric potential, its glycosidic derivatives were synthesized. On the basis of structural features and calculated lipophilicity coefficient (ClogP) the derivatives were classified as hydrophilic (i.e. those containing free sugar moiety) or lipophilic (i.e. those with alkylated or acylated sugar hydroxyls). The in vitro cytostatic and cytotoxic studies showed hydrophilic glycosides to be practically inactive against human cancer cell lines when compared to the free aglycone. On the contrary, lipophilic glycosides were significantly more active than the parent isoflavone although the correlation between ClogP and the activity was not clear. On the basis of GI50 and LC50 values two of the most active glycosides were found to be several times more potent in their cytostatic and cytotoxic effect than genistein. Additionally all lipophilic glycosides were revealed to exhibit different mode of action in comparison to genistein. It may suggest that these compounds do not undergo rapid biodegradation, either in culture media or inside cells, and exert their biological effects primarily as intact molecules.     

Synergistic anti-cancer effects of silibinin with conventional cytotoxic agents doxorubicin, cisplatin and carboplatin against human breast carcinoma MCF-7 and MDA-MB468 cells

Significant emphasis is being placed on combination chemotherapy of cancer using cytotoxic agents and naturally occurring chemopreventive agents, having different mechanisms of action with non-overlapping toxicity. In this regard, here we assessed whether a cancer preventive agent silibinin synergizes the therapeutic potential of doxorubicin (Dox), cisplatin or carboplatin, the chemotherapeutic drugs, in both estrogen-dependent and -independent human breast carcinoma, MCF-7 and MDA-MB468 cells, respectively. When tested alone, each of the four agents showed growth inhibition in both the cell lines in a dose- and a time-dependent manner. Based on their growth inhibitory effects, several combinations of silibinin (25-100 microM) with Dox (10-75 nM), cisplatin (0.2-2 microg/ml) or carboplatin (2-20 microg/ml) were next assessed for their synergistic, additive and/or antagonistic efficacy towards cell growth inhibition and apoptotic death. The strongest synergistic effects for cell growth inhibition [combination index (CI) 0.35 for MCF-7 and 0.45 for MDA-MB468 cells] were evident at a silibinin dose of 100 microM plus 25 nM Dox, in both the cell lines. Most of the CIs for other combinations of these three drugs with silibinin also suggested strong synergistic effects for cell growth inhibition in both MCF-7 and MDA-MB468 cells. In quantitative apoptosis studies, combination of silibinin with Dox resulted in much stronger apoptotic death compared to each agent alone in both cell lines. In case of silibinin combination with cisplatin, it showed no additional apoptotic effect in either cell line. Similarly, silibinin plus carboplatin combination showed stronger apoptotic effect only in MCF-7 cells. Together, these results suggest a possible synergism between silibinin and conventional cytotoxic agents for breast cancer treatment, and warrant further in vivo studies in pre-clinical breast cancer models.     

Synergistic effects of deuterium oxide and gemcitabine in human pancreatic cancer cell lines

PURPOSE: Pancreatic cancer still remains a treatment-refractory cancer. Standard therapy for metastatic cancer is gemcitabine (dFdC) chemotherapy. Since heavy water (deuterium oxide, D2O) was shown to be active in pancreatic cancer in vitro, we examined the simultaneous or sequential cytotoxic effects of D2O and dFdC in pancreatic cancer cell lines (AsPC-1, BxPC-3, and PANC-1). Moreover, we investigated the effect of D2O treatment on the colony formation of peripheral blood mononuclear cells (PBMNC) as well as the apoptosis inducing activity of D2O and dFdC and the regulation of tumor suppressor gene p21. RESULTS: Simultaneous incubation of human pancreatic carcinoma cells with D2O and dFdC led to a decrease of IC50 values of dFdC alone in all cell lines examined. Sequential application of D2O and dFdC caused synergistic effects. Treatment with 10-30% D2O did not show any significant inhibition effects on the colony formation of peripheral blood mononuclear cells (PBMNC), indicating limited adverse effects of D2O on bone marrow cells. Treatment with D2O in combination with dFdC significantly (p<0.05) increased the induction of apoptosis in PANC-1 and AsPC-1 cells and led to an overexpression of p21 tumor suppressor gene compared to incubation with dFdC alone. As the combination of D2O and dFdC might offer an additional option for the control of pancreatic cancer, this treatment should be investigated in a pancreas carcinoma animal model in order to scrutinize the in vitro data.     

托瑞米芬协同顺铂抑制A549细胞生长

目的：研究托瑞米芬（TOR）对人肺腺癌细胞系A549的毒性作用及其与顺铂（DDP）联用的协同效应，以期为肺癌的综合治疗提供新的方向。方法：用MTT显色法检测TOR及与DDP联用后对A549细胞的毒性作用，测定其A值。用流式细胞仪检测细胞DNA含量，Western Blotting法检测p53及p21蛋白表达，明确可能的机制。结果：TOR能直接抑制A549细胞的生长，＞或等于5μmol/L的ＴＯＲ浓度可明显增强DDP的细胞毒性作用，TOR可加强DDP对S期，G2及M期细胞的作用，且DDP加TOR后p21蛋白表达增加。结论：＞5μmol/L的TOR与DDP联用对A549细胞具有显著的协同抗肿瘤效应。其机制可能与DDP对细胞周期阻断的时相改变有关，且可能与p21蛋白诱导相关及可能和非p53依赖蛋白机制有关。     

Potent cytotoxic action of the immunotoxin SWA11-ricin A chain against human small cell lung cancer cell lines.

The cytotoxic activity profile of an immunotoxin, SWA11-ricin A chain, recognising a cell-surface antigen associated with human small cell lung cancer (SCLC), was examined in detail using a panel of SCLC, non-SCLC and non lung tumour cell lines in tissue culture. SWA11-ricin A chain was potently and selectively active against three SCLC cell lines of both classic and variant morphologies, inhibiting the incorporation of 3H-leucine with an IC50 of 5 x 10(-11) M. At a concentration of 1 x 10(-8) M, the SWA11 immunotoxin could selectively eliminate in excess of 99.9% of clonogenic tumour cells. Intoxication proceeded rapidly following a 4 h lag phase; the initial rate of protein synthesis inhibition occurred with a t50 of 2 h and a t10 of 7 h. The cytotoxic activity of SWA11-ricin A chain was potentiated by 100-fold in the presence of the carboxylic ionophore monensin at 1 x 10(-7) M. Kinetic studies revealed that monensin enhanced the rate of protein synthesis inhibition by two-fold and eliminated the lag phase suggesting a rapid effect on either the rate or route of internalisation. Studies with SWA11 could detect no influence of monensin on the rate of antibody internalisation and a transient delay in the delivery of internalised antibody to lysosomes was observed by immunoelectron microscopy.     

Synergistic cytotoxic effects of tumor necrosis factor, interferon-gamma and tamoxifen on breast cancer cell lines.

The combined effects of recombinant human tumor necrosis factor (TNF), interferon-gamma (IFN) and tamoxifen (TAM) on the proliferation of human breast cancer cell lines were investigated. In estrogen receptor positive MCF-7 cells, relatively resistant to TAM or TNF, cytotoxicity significantly increased in combinations of TNF and IFN, and of a cytokine and TAM. The cytotoxicity of TNF increased when cells were pretreated with IFN, but not vice versa. Sequential treatment with IFN following TNF and TAM also exhibited significant antiproliferative effect on both cell lines. The combined or sequential cytokines and TAM treatments are possible modalities to overcome breast cancers unresponsive to endocrine treatment.     

In vitro evaluation of a new nitrosourea,TCNU, against human small cell lung cancer cell lines

Summary The cytotoxic activity of a new nitrosourea, TCNU, was compared with that of BCNU in five human small cell lung cancer cell lines in vitro. TCNU was found to be equivalent or inferior to BCNU when compared on a microgram to microgram basis. If the potential of in vitro phase II trials for selection of new drugs can be validated, it can be concluded that TCNU is not superior to other nitrosoureas for the treatment of SCCL.This work was supported by grants from the Lundbeck Foundation     

Antitumor activity of magainin analogues against human lung cancer cell lines.

Magainin 1 and magainin 2, originally isolated from African clawed frog Xenopus laevis skin, inhibit the growth of bacteria and fungi. Synthetic magainin A (MAG A) and magainin G (MAG G) are more potent against bacteria and protozoa. In order to determine the antitumor activity of these analogues, we have tested these two analogues against six small cell lung cancer (SCLC) cell lines NCI-H82, NCI-H526, NCI-H678, NCI-H735, NCI-H841, and NCI-H889, which were known to differ by more than 10-fold in their sensitivity to different chemotherapeutic agents, and four normal human fibroblast cell lines. Semiautomated 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays of the six SCLC cell lines revealed average concentrations producing 50% inhibition (IC50) values of 2.6 microM (range, 0.49-9.30 microM) for cisplatin, 2.5 microM (range, 0.39-6.00 microM) for etoposide, and 138.8 nM (range, 55.0-450.0 nM) for doxorubicin. The average IC50 of MAG A was 8.64 microM (range, 6.23-11.7 microM) and that of MAG G was 8.82 microM (range, 4.44-12.5 microM) against the SCLC cell lines. Despite a 10-fold difference in sensitivity to standard chemotherapeutic agents, the IC50 of MAG A and MAG G differs by less than 3-fold. The average IC50 against four normal human fibroblast cell lines was 21.1 microM (range, 12.7-25.6 microM) for MAG A and 29.2 microM (range, 21.3-34.8 microM) for MAG G. Combined exposure to the IC50 concentration of MAG A or MAG G plus IC50 of etoposide or cisplatin decreased the percentage of surviving SCLC cells to 29.0% (range, 26.1-31.7%). MAG A or MAG G had an additive effect when used with standard chemotherapeutic agents. These data suggest that MAG A and MAG G have in vitro antitumor activity against SCLC cell lines.     

Induction of microsatellite mutations by oxidative agents in human lung cancer cell lines

Genomic instability has been associated with cancer development. Oxidative DNA damage seems to contribute to genetic instability observed in cancer. We have used human lung cancer cell lines carrying a plasmid vector containing a (CA)(13) microsatellite sequence to study frameshift mutations mediated by ROS-generating chemicals paraquat and hydrogen peroxide. Exposure of the cells to both paraquat and hydrogen peroxide resulted in significantly higher mutation frequencies compared with untreated control cells. Mutation frequencies up to 27-fold higher than the spontaneous mutation frequencies were obtained. The majority of the reversion mutants contained frameshift mutations within the target sequence. However, the pattern of deletions and additions was significantly different in the two cell lines. These results indicate that oxidative damage may play a role in instability of microsatellite sequences in vivo.     

Synergistic effects of pemetrexed and amrubicin in non-small cell lung cancer cell lines: Potential for combination therapy

The purpose is to examine the synergistic effect of pemetrexed (PEM) and amrubicin (AMR) on the proliferation of lung cancer cell lines. In vitro, dose-dependent synergistic effects of concurrent PEM and AMRol, which is an active metabolite of AMR were observed in A549 and H460 cells. In real-time RT-qPCR analysis and western blotting, expression of the target enzymes of PEM were suppressed in cells treated with amrubicinol alone. In vivo, AMR/PEM treatment also showed synergistic antitumor activity both in A549-bearing and H520-bearing mice. PEM and AMR work synergistically to inhibit the proliferation of several different lung cancer cell lines.     

托瑞米芬与表阿霉素联用对A549、H1299细胞生长与凋亡的影响

目的：探讨托瑞米芬（TOR）与表阿霉素（EADM）联用对人肺癌细胞株A549、H1299细胞生长与凋亡的影响及其机制.方法：用MTT比色法检测TOR的化疗增敏作用,用流式细胞仪检测细胞周期的变化及p-gp在两种肺癌细胞中的表达.结果：TOR（≥20μmol/L）能直接抑制两种细胞的生长,低剂量的TOR（5、10μmol/L）与EADM联用后的抑制率均低于单用EADM组（P＜0.01）,并呈现浓度依赖性.两者联用可引起两种肿瘤细胞凋亡,呈现浓度依赖性.两种细胞周期均发生明显变化.13.1?49细胞有p-gp的存在,44.9%H1299细胞有p-gp的存在.结论：低浓度的托瑞米芬与表阿霉素联用对两种细胞有明显的协同作用.A549细胞的TOR对EADM的协同作用较H1299细胞强.其化疗增敏效应可能与增加肿瘤细胞凋亡、改变细胞周期分布有关.P53基因可能参与了TOR对两种细胞的化疗增敏及逆转耐药的调节.     

Immunotoxins recognising a new epitope on the neural cell adhesion molecule have potent cytotoxic effects against small cell lung cancer.

The present study describes a comparison of two potent immunotoxins which utilise an identical targeting component, a monoclonal antibody (SEN7) specific for small cell lung cancer (SCLC), conjugated to two different effector components, blocked ricin (bR) and Pseudomonas exotoxin A (PE). SEN7 recognises a novel epitope on the neural cell adhesion molecule (NCAM) which is highly associated with SCLC. The immunotoxins SEN7-PE and SEN7-bR were selectively and potently active against a number of SCLC cell lines, of both classic and variant morphologies, inhibiting the incorporation of [3H]leucine with IC50 values ranging between 22 pM and 85 pM and between 7 pM and 62 pM for SEN7-PE and SEN7-bR respectively. Intoxication by both immunotoxins proceeded rapidly following short 2 h lag phases; the initial rates of protein synthesis inhibition occurred with t50 values of 6.5 h for SEN7-PE and 5.5 h for SEN7-bR. Monensin drastically enhanced the cytotoxic activity of the weakly active SEN7-ricin A-chain by 2,100-fold and of SEN7-bR by 80-fold but had no effect on SEN7-PE. In limiting dilution assays, four and more than 4.5 logs of clonogenic SW2 tumour cells were selectively eliminated from the cultures during continuous exposure to the immunotoxins SEN7-PE and SEN7-bR respectively, while antigen-negative cells required up to 1,000-fold more drug for a similar cell kill. SW2 cells surviving SEN7-bR treatment in the cultures did not express NCAM and consequently were not selectively killed by SEN7 immunotoxins. SW2 cells surviving continuous exposure to SEN7-PE showed no alteration in NCAM expression but were more resistant to intoxication mediated by PE. These cells were still sensitive to SEN7-bR.     

δ-Aminolevulinic acid cytotoxic effects on human hepatocarcinoma cell lines

Background  

Acute Intermittent Porphyria is a genetic disorder of heme metabolism, characterized by increased levels of porphyrin precursors, δ-aminolevulinic acid (ALA) and porphobilinogen (PBG). ALA has been reported to generate reactive oxygen species and to cause oxidative damage to proteins, subcellular structures and DNA. It is known that oxidative stress can induce apoptosis. The aim of this work was to study the cytotoxic effect of ALA on two hepatocarcinoma cell lines.     

Monoclonal antibodies against two human lung carcinoma cell lines

Monoclonal antibodies against 2 human lung carcinoma cell lines (E14 and BEN) were prepared by production and cloning of somatic cell hybrids between the murine myeloma NS1, and spleens from E14- and BEN-immune BALB/c mice. Approximately 2000 hybrid culture supernatants were screened for antibody simultaneously against the immunizing cell line and lung fibroblasts (573 Lu) using a radiolabelled Protein A binding assay. Although the vast majority secreted antibodies which recognized species-specific antigens, a few supernatants showed marked differential reactivity against E14 or BEN. These were cloned and subsequently tested against a panel of up to 25 human cell lines originating from different neoplastic and non-neoplastic tissues. Two anti-E14 clones (3E19.8 and 4EAB3.7) displayed preferential activity against lung cancer cell lines, but a low level of reactivity was also detectable with cell lines of different tissue provenance. The antibodies of 3 anti-BEN clones (7B3.5, 7B5.4, 7B17.7) likewise recognized antigens present to a higher density on lung cancer cell lines but were also reactive (to a variable extent for the different clones) with a diversity of other tumour cell lines. The antibodies of 2 further clones were exceptional in so far as one (7BC9.1) reacted only with BEN and WIDR (colorectal cancer) cells, while another (7B24.4) reacted, with apparent exclusivity, against BEN cells. With the exception of the latter, the distinction in antigen expression between many of the cell lines was quantitative rather than qualitative and the emergent picture is one of random expression of individual determinants on several disparate types of cancer cells, rather than restriction to cells of a given morphological type or histogenic derivation.     

Interaction of fluorouracil and interferon in human colon cancer cell lines: cytotoxic and cytokinetic effects.

Fluorouracil (FUra) is the most active agent in advanced colorectal carcinoma, and this activity can be enhanced by various modulating agents both in vitro and in vivo. To determine whether interferon (IFN) is capable of augmenting the cytotoxic and cytokinetic effects of FUra, combinations of FUra and IFN alpha, -beta, and -gamma were tested against 2 human colon cancer cell lines in vitro. In a clonogenic assay, IFN alpha and -beta, at concentrations that produced less than 1 log cell kill, significantly increased the cytotoxic effects of FUra in both cell lines. IFN gamma also enhanced the cytotoxic effects of FUra, but unlike IFN alpha and -beta, only at the highest concentrations tested. Median effects analysis demonstrated that all 3 IFNs exhibited synergy with FUra. Combinations of IFNs were no more effective at modulating FUra activity than single agent IFN. Flow cytometric studies indicated that these effects did not correlate with cytokinetic alterations. Only the combination of FUra and IFN beta produced cytokinetic effects different from those of FUra alone. Incubation with IFN alpha or IFN gamma for 24 h resulted in only modest cytokinetic alterations, and they did not modify the effects of FUra. These results indicate that IFN is capable of increasing the cytotoxic actions of FUra and that this is separable from any cytokinetic effects produced by the interferons.