Potentiation of 5-fluorouracil, chromomycin A3, and bleomycin by amphotericin B or polymyxin B in transformed fibroblastic cells

Repurposing itraconazole as an anticancer agent

Itraconazole, a common anti-fungal agent, has demonstrated potential anticancer activity, including reversing chemoresistance mediated by P-glycoprotein, modulating the signal transduction pathways of Hedgehog, mechanistic target of rapamycin and Wnt/β-catenin in cancer cells, inhibiting angiogenesis and lymphangiogenesis, and possibly interfering with cancer-stromal cell interactions. Clinical trials have suggested the clinical benefits of itraconazole monotherapy for prostate cancer and basal cell carcinoma, as well as the survival advantage of combination chemotherapy for relapsed non-small cell lung, ovarian, triple negative breast, pancreatic and biliary tract cancer. As drug repurposing is cost-effective and timesaving, a review was conducted of preclinical and clinical data focusing on the anticancer activity of itraconazole, and discusses the future directions for repurposing itraconazole as an anticancer agent.

Reversal effects of antifungal drugs on multidrug resistance in MDR1-overexpressing HeLa cells

In this study, the antiproliferative effects of vinblastine (VLB), paclitaxel (TXL), doxorubicin (DXR), daunorubicin (DNR) and 5-fluorouracil (5-FU) were assessed in the human cervical carcinoma cell line HeLa-Ohio (HeLa) and Hvr100-6 cells, established by growing the parental HeLa cells in the presence of progressively greater concentrations of VLB in the culture medium. Flow cytometric analysis indicated the induction of MDR1 (P-glycoprotein) in Hvr100-6 cells with no alterations in levels of multidrug resistance-associated protein (MRP). Resistance to VLB, TXL, DXR and DNR was found in Hvr100-6 cells with relative resistances of ca. 300, 4000, 50 and 200, respectively, whereas no resistance was found to 5-FU. The reversal effects of antifungal drugs, fluconazole, itraconazole, ketoconazole, miconazole and amphotericin B on multidrug resistance were also assessed using Hvr100-6 cells. Itraconazole was found to have potent reversal effect on the resistance to VLB and TXL, but the others had no such effect. This reversal effect of itraconazole was concentration-dependent, with dose modifying factors of 3.2, 10.1 and 435.7 at 0.1, 0.25 and 0.5 microM of itraconazole, respectively. In addition, this reversal effect of itraconazole was explained by the inhibition of accumulation of the anticancer drugs.

Interactions between anticancer drugs and other clinically used pharmaceuticals. A review

Drug interactions are increasingly common, since clinical practice is getting more complex with the flood of new drugs. Simultaneously, the increased life expectancy of the population increases the number of individuals likely to receive multiple prescriptions. Cytotoxic drugs generally have a narrow therapeutic index, and are delivered at doses close to toxic levels. Consequently, a slight increase in biological activity caused by an interaction with other concomitantly administered drugs could be deleterious to the patient. Interactions between drugs can sometimes also be used in a positive way, i.e. to increase the therapeutic ratio and overcome drug resistance. Interactions between different cancer treatment modalities have attracted considerable interest. However, much less interest has been devoted to interactions between anticancer drugs and other pharmaceuticals. The purpose of this review is to summarize data about the interactions between anticancer drugs and other clinically used drugs with regard to effects on tumor and toxicity.

Potentiation of antiviral activity of acyclovir by polyene macrolide antibiotics

The potentiation of the antiviral activity of acyclovir [9-[(2-hydroxyethoxy)methyl]guanine] by polyene macrolide antibiotics has been studied as a function of the macrolide structure. The 12 polyenes chosen for this study represented the major structural groups of these antibiotics and induced in mammalian cells repairable membrane alterations or irreversible cell damage. The potentiating activity of the polyene macrolides was determined based on the differential decrease of in vitro production of infectious virions in the presence of acyclovir alone or in combination with the polyene. Pseudorabies virus, a representative herpesvirus susceptible to acyclovir, was replicated in BHK-21 cells grown in serum-free medium to avoid the interference of serum factors in the polyene macrolide-cell interaction. The potentiation activity of the polyene antibiotics was concentration dependent. The enhancement of the antiviral activity of acyclovir was observed at polyene concentrations which had no direct effect on pseudorabies virus replication in BHK-21 cells. The optimal potentiating concentrations of polyenes were 2 to 15 times lower than that inducing 50% of potassium efflux from BHK-21 cells. The highest potentiating activity was observed for the methyl ester of the trimethylammonium derivative of aureofacin B, which reduced the pseudorabies virus titer by two orders of magnitude. Potentiation by polyene macrolides appeared to coincide with the K+-dependent membrane repair process. The acyclovir potentiating activity was associated with polyene macrolide antibiotics having a large and rigid macrolide ring (amphotericin B and aureofacin). Polyene antibiotics with small and rigid (pimaricin and filipin) or large but flexible (nystatin A1 and lienomycin) macrolide rings showed no potentiation of the antiviral effect of acyclovir.

Inhibition of stomal recurrence in laryngectomy with preoperative far therapy. A statistical evaluation

FAR therapy is effective for cancers of the head and neck, in particular laryngeal cancer. This combined chemoradiotherapy consists of 5-FU, vitamin A and radiation. We found 10% stomal recurrences in reviewing 112 patients who had been treated with total laryngectomy. Stomal recurrences after total laryngectomy occur frequently in patients undergoing an emergency tracheotomy. We studied 33 such patients divided into 2 groups, on the basis of whether laryngectomy had been carried out after the emergency tracheotomy plus preoperative FAR therapy, or whether laryngectomy had been carried out without preoperative FAR therapy. The incidence of stomal recurrence was less among those given preoperative FAR therapy and was statistically significant. Such being the case, preoperative FAR therapy seems to e prophylactically effective against stomal recurrence after emergency tracheotomy.

Lymphocyte DNA in aplastic anaemia

Using ultracentrifugation on alkaline sucrose density gradients the DNA of lymphocytes from 14 patients with aplastic anaemia and 23 controls was studied before and after exposure to bleomycin, an agent known to cause strand breaks in DNA. Before exposure to bleomycin the DNA from aplastic patients had more strand breaks than the DNA from the controls of similar ages. Following exposure to bleomycin an abnormal number of DNA strand breaks was produced in 10 of 14 patients and this molecular evidence of drug sensitivity correlated well with the sensitivity of the proliferating lymphocytes to bleomycin in tissue culture. Furthermore, two relatives of patients with aplastic anaemia showed similar abnormality of DNA before and after exposure to bleomycin and increased sensitivity to bleomycin in tissue culture. These results suggest that an abnormality of DNA structure and/or repair may be present in some patients with aplastic anaemia.

Classification of polyene antibiotics according to their synergistic effect in combination with bleomycin A2 or fusidic acid

Five polyene antibiotics were compared for their effects on colony formation of either Chinese hamster V79 or Saccharomyces cerevisiae cells. A 10 to 40 times higher concentration of amphotericin B (heptaene) or nystatin (degenerated heptaene) was necessary to inhibit colony formation of hamster cells than that needed to inhibit colony formation of yeast cells. In contrast, colony formation of both hamster and yeast cells was inhibited to the same extent by similar concentrations of filipin (pentaene), pentamycin (pentaene), or pimaricin (tetraene). The five polyene antibiotics were also compared for their effects on colony formation of either V79 or S. cerevisiae cells when combined with a nonpolyene antibiotic, fusidic acid or bleomycin A2. Amphotericin B or nystatin could augment the cytocidal effect of fusidic acid but not that of bleomycin A2, whereas pentamycin or pimaricin could augment the cytocidal effect of both fusidic acid and bleomycin A2 against hamster and yeast cells. Filipin was found to enhance the action of fusidic acid and bleomycin upon growth of mammalian cells, whereas the pentaene polyene significantly potentiated the action of fusidic acid, but not that of bleomycin A2, against S. cerevisiae. It was therefore suggested that these polyene antibiotics be classified into two groups: group 1 (pimaricin, pentamycin, and filipin) and group 2 (amphotericin B and nystatin).

Antitumor effect of a combination of 6-methylthioinosine and amphotericin B on mouse leukemia L1210

Antileukemic activity of 5 kinds of sulfur-containing purine ribonucleosides were examined in the presence and absence of amphotericin B against L1210 in mice. Among these compounds, 6-methylthioninosine was potentiated by amphotericin B. 6-Methylthioinosine in combination with amphotericin B produced a 75% increase in the lifespans, which was greater than the increase in lifespans by 6-methylthioinosine (38%) or amphotericin B alone (2%). Antitumor effects of other sulfur-containing ribonucleosides, such as 6-thiocyanatoguanine, 6-thiocyanatopurine, 6-thiocyanatoinosine, and 6-methylthiopurine, were not augmented by amphotericin B.

The effect of amphotericin B-deoxycholate on proliferation and protein synthesis in human skin fibroblast cultures

Cultures of adult human skin fibroblasts were grown in the presence of the recommended antifungal dose (3 microgram per ml) of amphotericin B-deoxycholate. A reduction in cell culture growth, measured as DNA content and protein content per culture, was observed. However, radioisotope incorporation into noncollagen protein and, to a lesser extent, collagen protein was enhanced. These effects were due to amphotericin B, not to deoxycholate. These observations were made under several growth conditions and indicate that cell proliferation or isotope-labeling studies in fibroblasts in the presence of amphotericin B-deoxycholate are susceptible to errors in interpretation.

Polyene macrolide antibiotic cytotoxicity and membrane permeability alterations. I. Comparative effects of four classes of polyene macrolides on mammalian cells

The relationship between polyene macrolide-induced early membrane damage and cytotoxicity in B1 (hamster), B82 (mouse), and RAG (mouse) cells has been investigated. Filipin (FIL) induced the greatest immediate damage, as monitored by 51Cr release, followed by mediocidin (MED), amphotericin B-deoxycholate (Fungizone) (FZ) and pimaricin (PIM). For long term effect, PIM was the least toxic followed by MED, FZ, and FIL as indicated by 24-hour survival, 72-hour viability, and growth rate of cells. In evaluating polyene macrolide-induced permeability alterations and cytotoxicity two types of interactions with mammalian cells were found: (1) cell toxicity at polyene macrolide levels not eliciting immediate membrane permeability changes; and (2) immediate membrane damage without long range toxicity.

The effect of amphotericin B on the survival of brain-tumor-bearing mice treated with CCNU

The membrane-active polyene, amphotericin B (AMB) has been shown to enhance or potentiate the effects of various chemotherapeutic agents against tumor cells in tissue culture. Because of the need to increase the efficacy of the nitrosoureas in brain-tumor chemotherapy, we have studied the effect of the nitrosourea, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), with or without AMB pretreatment. The intraperitoneal administration of 25 mg/kg of AMB 24 hours before 5, 10, 20 or 30 mg/kg of intraperitoneal CCNU did not result in a significant improvement in survival. The failure of intraperitoneal AMB to potentiate the effect of CCNU was likely a failure in drug delivery, since AMB crosses the blood-brain barrier very poorly. To circumvent the drug-delivery problem, AMB was administered intracerebrally directly into the tumor-bearing hemisphere. With 0.5 mg/kg of intracerebral AMB administered 24 hours before 10 mg/kg CCNU was given intraperitoneally, the life-span was significantly increased over the control group. The same dose of CCNU alone did not significantly increase survival. When 0.2, 0.5, or 1.0 mg/kg AMB was administered intracerebrally 24 hours before 20 mg/kg of interaperitoneal CCNU, survival was significantly increased over those groups receiving the same dose of CCNU alone. It is concluded that direct intracerebral administration of AMB enhances or potentiates the therapeutic effect of CCNU in this brain-tumor model.

Selection of mouse X hamster hybrids using HAT medium and a polyene antibiotic

In the present study we tested the feasibility of utilizing a structurally modified polyene antibiotic, amphotericin B methyl ester (AME), as a half-selection agent for isolating somatic cell hybrids. By using HAT medium supplemented with AME we have isolated interspecific mouse-hamster hybrids from mixed cultures of mouse (TK-C1 ID or HPRT-A9) and hamster (BHK/C 13) cells fused with Sendai virus, lysolecithin or polyethylene glycol. Hybrid cells proliferated and clones were isolated after 2 to 3 weeks growth in three changes of HAT-AME medium and subsequent growth in HAT medium alone. In contrast, genetically deficient parental C1 1D or A9 cells and AME-sensitive BHK/C 13 cells were killed using a similar growth protocol. The described technique is simple, efficient and permits one to use a cell line without a genetic defect in combination with a genetically deficient cell type in hybrid formation.

The effect of fetal bovine serum on polyene macrolide antibiotic cytotoxicity and antifungal activity

The relationships between fetal bovine serum (FBS) concentration and polyene macrolide antibiotic cytotoxicity to animal cells and to fungi were evaluated. The toxicity of amphotericin B (AB) and its derivative, amphotericin B methyl ester (AME), toward KB cells was found to be directly related to fetal bovine serum concentration. At higher FBS levels, increased concentrations of AB and AME were required to reduce 72-hr KB viable cell numbers of 50% of control values. Similarly, polyene macrolide antibiotic levels required to inhibit the growth of Saccharomyces cerevisiae to 50% of controls, and for obtaining minimum fungicidal concentrations (MFC), were greater when higher levels of FBS were used. In addition, AME was less toxic than AB toward KB cells grown in media containing 2, 5, 10, 15 or 20% FBS, whereas the antifungal activities of AB and AME were similar. AME was also capable of eliminating Candida albicans, Saccharomyces cerevisiae, Aspergillus niger or Fusarium moniliforme from KB cultures at antibiotic levels which exhibited less cell toxicity than did the concentrations of AB required for a similar response. These findings indicate that AME may be a potentially useful antifungal antibiotic for tissue culture systems.

The effect of bleomycin and pentamycin in combination on the survival of EMT6 mouse tumour cells in vitro and in vivo

The combined effect of bleomycin and the polyene antibiotic, pentamycin, upon the survival of EMT6 tumour cells has been studied both in vitro and in vivo. During growth of the cells as a monolayer in vitro, a very marked potentiation of bleomycin action is seen during the exponential and early plateau phases of growth, but little potentiation occurs in late plateau phase. The effect of exposing the cells to the two drugs consecutively in either order is greater than if the two agents are used at the same time. In vivo, it does not appear that pentamycin can greatly increase the cytocidal effect of bleomycin.

Reduced toxicity of amphotericin B methyl ester (AME) vs. amphotericin B and fungizone in tissue culture

The comparative toxicities of amphotericin B methyl ester (AME), the parent antibiotic amphotericin B (AB), and the deoxycholate solubilized complex of AB, Fungizone (FZ), toward five cell lines has been determined as measured by early membrane damage (51Cr release), 24 hr survival, 72 hr viability, and growth rate. Cells used were of turtle (TH-1), marsupial (PT K2), human MA 160), rabbit (RK-13) and hamster (BHK-21) origin. AME: (a) caused less membrane damage at 1 hr than AB or FZ; (b) was less toxic than AB or FZ as indicated by 24 hr cell survival and 72 hr cell viability; and (c) was required in higher levels than AB or FZ to reduce the growth rate of all five cell lines. Spectrophotometric analysis of residual polyene levels indicated that AME had good stability in tissue culture medium. Previous studies have indicated that AME has the same in vitro antifungal activity as the parent antibiotic AB (1, 2). These findings suggest that AME may prove to be superior to AB and FZ for use as an antifungal agent in tissue culture systems.

Differential potentiation by nystatin of the effect of antibiotics on yeast and mammalian cells

The effect of the polyene antibiotic nystatin, used in combination with several other antibiotics, on the membranes of Candida albicans SC#8169 (yeast) cells and of Chinese hamster ovary and 3T3 (mammalian) cells was investigated. It was concluded from determinations of the viability of the yeast cells and from measurements of deoxyribonucleic acid synthesis by the mammalian cells that nystatin acts synergistically with several antibiotics on yeast cells, but not on CHO and 3T3 cells. This selective action of nystatin may prove useful in chemotherapy.