... Salinomycin (SAL), a broad spectrum antibiotic and a coccidiostat has been found to counter tumour resistance and kill cancer stem cells with better efficacy than the existing chemotherapeutic agents; paclitaxel and doxorubicin. This refocused its importance for treatment of human cancers. In this study, we studied the in vitro drug metabolism and pharmacokinetic parameters of SAL. SAL undergoes rapid metabolism in liver microsomes and has a high intrinsic clearance. SAL metabolism is mainly mediated by CYP enzymes; CYP3A4 the major enzyme metabolising SAL. The percent plasma protein binding of SAL in human was significantly lower as compared to mouse and rat plasma. CYP inhibition was carried out by chemical inhibition and recombinant enzyme studies. SAL was found to be a moderate inhibitor of CYP2D6 as well as CYP3A4. As CYP3A4 was the major enzyme responsible for metabolism of SAL, in vivo pharmacokinetic study in rats was done to check the effect of concomitant administration of Ketoconazole (KTC) on SAL pharmacokinetics. KTC, being a selective CYP3A4 inhibitor increased the systemic exposure of SAL significantly to 7-fold in AUC0-a and 3-fold increase in Cmax of SAL in rats with concomitant KTC administration.
IDENTIFICATION AND USE: Salinomycin is a veterinary drug used for the prevention of coccidiosis in broiler, roaster and replacement chickens caused by Eimeria tenella, E. necatrix, E. acervulina, E. maxima, E. brunetti and E. mivati. It is also used for the prevention of coccidiosis in quail caused by Eimeria dispersa and E. lettyae. HUMAN EXPOSURE AND TOXICITY: The cytotoxic and genotoxic effects of salinomycin were investigated in human non-malignant cells. Primary human nasal mucosa cells (monolayer and mini organ cultures) and peripheral blood lymphocytes from 10 individuals were used to study the cytotoxic effects of salinomycin (0.1-175 uM) by annexin-propidiumiodide- and MTT-test. The comet assay was performed to evaluate DNA damage. Additionally, the secretion of interleukin-8 was analyzed by ELISA. Flow cytometry and MTT assay revealed significant cytotoxic effects in nasal mucosa cells and lymphocytes at low salinomycin concentrations of 10-20 uM. No genotoxic effects could be observed. IL-8 secretion was elevated at 5 uM. Salinomycin-induced cytotoxic and pro-inflammatory effects were seen at concentrations relevant for anti-cancer treatment. ANIMAL STUDIES: There are numerous reports of fatal outcomes when salinomycin is accidently fed to various animals. A sudden outbreak of mortality in one house of 600 48-week-old male breeder turkeys on a five-house turkey breeder farm was suspected to be feed-related. The turkeys gasped and became recumbent; 21.7% of affected turkeys died. Histological lesions, limited to skeletal muscle, consisted of degeneration and necrosis and were judged compatible with ionophore toxicosis. Feed samples from the affected house were analyzed and shown to contain 13.4 to 18.4 g of salinomycin per ton of feed. To further study the effects of salinomycin on turkeys, five 7-day trials using 336, 24, 24, 40, and 40 male turkeys when 7, 11, 15, 27, and 32 weeks of age, respectively. Salinomycin became more toxic as the age of the turkeys increased. When 7-week-old turkeys were fed diets containing 44 or 66 ppm salinomycin, only 1 of 84 died; when turkeys 27 or 32 weeks of age were fed those amounts, 13 of 20 died. Salinomycin at 22 ppm tended to depress rate of growth at young ages and to prevent or decrease growth and to increase mortality at older ages. Accidental poisonings were also reported in six horses fed salinomycin. The range of signs, including anorexia, colic, weakness and ataxia bore similarities to those described in horses poisoned with the related ionophore monensin. In another poisoning, horses were fed a concentrate containing 61 mg/kg salinomycin as faulty prepared by the manufacturer. All horses developed severe clinical signs of intoxication. Despite therapy eight horses died within three to six days. Ten others became recumbent and had to be euthanized. Only six horses survived. The dominating laboratory results were very high enzyme levels and alkalosis. The most characteristic clinical change appeared as paralysis of the hindlimbs. An outbreak of toxic polyneuropathy in cats that had ingested dry cat food contaminated with salinomycin has also been reported. Epidemiologic and clinical data were collected from 823 cats, or about 1% of the cats at risk. In 21 affected cats, postmortem examination was performed. The affected cats had acute onset of lameness and paralysis of the hindlimbs followed by the forelimbs. Clinical and pathologic examination indicated a distal polyneuropathy involving both the sensory and motor nerves. The clinical signs and pathology in an outbreak of toxicity in feedlot cattle attributed to the ingestion of toxic levels of salinomycin over an extended period of 11 weeks have also been reported. Thirty-nine out of 380 cattle developed signs consistent with cardiac failure and 8 of these died. Clinical signs included dyspnea, tachypnea, tachycardia, and exercise intolerance. Two cattle were necropsied and in one there were macroscopic lesions suggestive of congestive heart failure, namely pulmonary edema, hydrothorax and hepatomegaly. Histopathology revealed a chronic cardiomyopathy characterized principally by extensive myocardial fiber atrophy with multifocal hypertrophy and interstitial and replacement fibrosis. Hepatic and pulmonary lesions were consistent with those of congestive cardiac failure. Finally, 100% mortality was reported in a herd of sheep that were given feed containing salinomycin. The morning after the feeding, 78 sheep were found dead and one of them showed convulsive seizures. Postmortem examination revealed pulmonary congestion and edema, hemorrhages in abomasum, large pale kidney and white streak lines in myocardium.
Hepatocellular carcinoma (HCC) is one of the few cancers in which a continuous increase in incidence has been observed over several years. Drug resistance is a major problem in the treatment of HCC. In the present study, we used salinomycin (Sal) and 5-fluorouracil (5-FU) combination therapy on HCC cell lines Huh7, LM3 and SMMC-7721 and nude mice subcutaneously tumor model to study whether Sal could increase the sensitivity of hepatoma cells to the traditional chemotherapeutic agent such as 5-FU. The combination of Sal and 5-FU resulted in a synergistic antitumor effect against liver tumors both in vitro and in vivo. Sal reversed the 5-FU-induced increase in CD133(+) EPCAM(+) cells, epithelial-mesenchymal transition and activation of the Wnt/beta-catenin signaling pathway. The combination of Sal and 5-FU may provide us with a new approach to reverse drug resistant for the treatment of patients with HCC.
Chemotherapy for soft tissue sarcomas remains unsatisfactory due to their low chemosensitivity. Even the first line chemotherapeutic agent doxorubicin only yields a response rate of 18-29%. The antibiotic salinomycin, a potassium ionophore, has recently been shown to be a potent compound to deplete chemoresistant cells like cancer stem like cells (CSC) in adenocarcinomas. Here, we evaluated the effect of salinomycin on sarcoma cell lines, whereby salinomycin mono- and combination treatment with doxorubicin regimens were analyzed. To evaluate the effect of salinomycin on fibrosarcoma, rhabdomyosarcoma and liposarcoma cell lines, cells were drug exposed in single and combined treatments, respectively. The effects of the corresponding treatments were monitored by cell viability assays, cell cycle analysis, caspase 3/7 and 9 activity assays. Further we analyzed NF-kappaB activity; p53, p21 and PUMA transcription levels, together with p53 expression and serine 15 phosphorylation. The combination of salinomycin with doxorubicin enhanced caspase activation and increased the sub-G1 fraction. The combined treatment yielded higher NF-kappaB activity, and p53, p21 and PUMA transcription, whereas the salinomycin monotreatment did not cause any significant changes. Salinomycin increases the chemosensitivity of sarcoma cell lines - even at sub-lethal concentrations - to the cytostatic drug doxorubicin. These findings support a strategy to decrease the doxorubicin concentration in combination with salinomycin in order to reduce toxic side effects.
A factorial design (2 by 3) was used to evaluate the interaction between aflatoxin (0, 2.5, & 5 mg per kg) & salinomycin (1, 60 g per ton (909 kg)). There were four replicates of 10 chicks per treatment. ... No significant interaction was observed between aflatoxin & salinomycin on any of the parameters measured.
This study was aimed to investigate the effect of salinomycin combined with vincristine on the proliferation and apoptosis of Jurkat cells and its possible mechanisms. The proliferation of Jurkat cells was examined by CKK-8 assay. Flow cytometry was used to assess cellular apoptosis. Levels of BCL-2, caspase-3, and caspase- 8 were measured by Western blot. The salinomycin or vincristine, either alone or in combination, inhibited the proliferation of Jurkat cells in a dose-dependent manner. Salinomycin combined with vincristine produced more obvious inhibition of cell proliferation than either compound used alone (P<0.05). Western blot analysis showed that the combined use of Sal and VCR reduced the expression of BCL-2 protein, and increased expression of caspase 3 and caspase 8 protein, more significantly. Furthermore, combination of Sal and VCR synergistally promoted apoptosis of the Jurkat cells (P<0.05). The combination of salinomycin and vincristine synergistically inhibits proliferation and promotes apoptosis of T-cell acute lymphoblastic leukemia Jurkat cells.
Salinomycin was administered to chickens orally and intravenously to determine blood concentration, kinetic behavior, bioavailability and tissue residues. The drug was given by intracrop and intravenous routes in a single dose of 20 mg kg-1 body-weight. The highest serum concentrations of salinomycin were reached half an hour after oral dosage with an absorption half-life (t0.5(ab)) of 3.64 hours and elimination half-life (t0.5(beta)) of 1.96 hours. The systemic bioavailability percentage was 73.02 per cent after intracrop administration, indicating the high extent of salinomycin absorption from this route in chickens. Following intravenous injection the kinetics of salinomycin can be described by a two-compartment open model with a t1/2(alpha) of 0.48 hours, Vd ss (volume of distribution) of 3.28 litre kg-1 and Cl(beta) (total body clearance) of 27.39 ml kg-1 min-1. The serum protein-binding tendency of salinomycin as calculated in vitro was 19.78 per cent. Salinomycin concentrations in the serum and tissues of birds administered salinomycin premix (60 ppm) for two weeks were lower than those after administration of a single intracrop dose of pure salinomycin (20 mg kg-1 bodyweight). The highest concentration of salinomycin residues were present in the liver followed by the kidneys, muscles, fat, heart and skin. No salinomycin residues were detected in tissues after 48 hours except in the liver and these had disappeared completely by 72 hours.
