As a member of the phenothiazine family, thioridazine (THIO) is a potent anti-anxiety and anti-psychotic drug. Recent studies have reported that THIO could suppress the growth of several types of cancer cells. However, the effect of THIO on colorectal cancer stem cells (CSCs) has not been investigated. In the present study, we examined the effect of THIO on viability of CSCs isolated from the human colon cancer cell line HCT116 and its colony-formation ability, along with its stem cell-specific gene expression. The CSCs, EpCAM+ and CD44+ subpopulations from HCT116 cells were isolated using immunomagnetic beads. After incubation with several concentrations of THIO, we evaluated the proliferation and invasion ability of colon CSCs, as well as cell apoptosis. We found that THIO significantly suppressed the proliferation and invasion of colon CSCs and induced cell apoptosis in a concentration-dependent manner. The expression of some apoptosis genes (Bax and caspase-3) was upregulated after treatment with THIO, while that of the anti-apoptosis gene Bcl-2 was downregulated. Moreover, the CSC mitochondrial membrane potential was downregulated. Overall, this study showed that THIO inhibits the proliferation of CSCs derived from the HCT116 cell line through induction of apoptosis, and thus, could be a promising agent for the treatment of colon cancer and worthy of exploring in prospective clinical studies.
Abstract. Salinomycin is a monocarboxylic polyether antibiotic that has been reported to induce apoptosis in various types of cancer cells with specificity for cancer stem cells. However, its anticancer effect in colorectal cancer stem cells has never been reported. In the present study, we examined the ability of salinomycin to induce cell death in the colorectal cancer stem cell line CD44 + EpCAM + HCT-116, and we measured its in vivo tumor inhibition capacity. Salinomycin dose-dependently induced cytotoxicity in the CD44 + EpCAM + HCT-116 cells and inhibited colony formation. Salinomycin treatment was shown to induce apoptosis, as evidenced by nuclear fragmentation, an increase in the proportion of acridine orange/ethidium bromide-positive cells and an increase in the percentage of Annexin V-positive cells. Apoptosis was induced in colorectal cancer stem cells in a caspase-dependent manner, as shown by an increase in the levels of cleaved caspase-3, -8 and -9. JC-1 staining further revealed that salinomycin induced colorectal cancer cell apoptosis via the mitochondrial pathway. In addition, salinomycin treatment of xenograft mice inhibited the growth of tumors derived from the CD44 + EpCAM + HCT-116 cells. The present study demonstrated that the antibiotic salinomycin exerts an anti-colorectal cancer effect in vitro and in vivo, suggesting salinomycin as a potential drug for colorectal cancer therapy. IntroductionColorectal cancer (CRC) is the third most common malignancy worldwide, accounting for ~10% of all cancer cases and CRC is one of the most common causes of death related to gastrointestinal cancers (1-3). Although the incidence rates of colon cancer have declined somewhat, current therapies are associated with serious side-effects, high cost and recurrence rates exceeding 50%, primarily due to the development of acquired chemoresistance to conventional chemotherapeutics (4,5).Emerging data suggest that malignant tumors contain a small distinct population of cancer stem cells (CSCs), which are responsible for tumor initiation and propagation (6). Stem cell research and the cancer stem cell (CSC) hypothesis have shown that colonic stem cells or CSCs are involved in tissue regeneration and colonic carcinogenesis (7-9). Drug-resistant CSCs are thought to be one of the key causes of CRC treatment failure, and it is hypothesized that these cells are ultimately the likely cause of metastasis and tumor recurrence (10-12). Most modern treatments are ineffective against solid tumors and this may be the result of the increased resistance of CSCs (13). Therefore, it is vital to find novel therapeutic methods to eradicate CSCs and enable the development of more effective treatment protocols (14).Salinomycin is a 751-Da monocarboxylic polyether antibiotic, which was initially used to eliminate bacteria, fungi and parasites and is fed to ruminants to improve nutrient absorption and feeding efficiency (15,16). This compound is now considered an important anticancer drug candidate (17,18). It has recently been reporte...
Abnormal aggregation and deposition of Aβ is one of the causative agents for Alzheimer's disease. The development of inhibitors for Aβ aggregation has been considered a possible method to prevent and treat Alzheimer's disease. Edible sea cucumbers contain many bioactive molecules, including saponins, phospholipids, peptides, and polysaccharides. Herein, we report that polysaccharides extracted from sea cucumber Cucumaria f rondosa could reduce the aggregation and cytotoxicity of Aβ40. By utilizing multiple biochemical and biophysical instruments, we found that the polysaccharides could inhibit the aggregation of Aβ40. A chemical kinetics analysis further suggested that the major inhibitory effects of the polysaccharides were achieved by disassembling mature fibrils, which in turn reduced the cytotoxicity of Aβ. These results suggested that the polysaccharides extracted from sea cucumber could be used as an effective inhibitor for Aβ.
Dual-targeted nanoparticles are gaining increasing importance as a more effective anticancer strategy by attacking double key sites of tumor cells, especially in chemophotodynamic therapy. To retain the nuclei inhibition effect and enhance doxorubicin (DOX)-induced apoptosis by mitochondrial pathways simultaneously, we synthesized the novel nanocarrier (HKH) based on hollow carbon nitride nanosphere (HCNS) modified with hyaluronic acid (HA) and the mitochondrial localizing peptide D[KLAKLAK]2 (KLA). DOX-loaded HKH nanoparticles (HKHDs) showed satisfactory drug-loading efficiency, excellent solubility, and very low hemolytic effect. HA/CD44 binding and electrostatic attraction between positively charged KLA and A549 cells facilitated HKHD uptake via the endocytosis mechanism. Acidic microenvironment, hyaluronidase, and KLA targeting together facilitate doxorubicin toward the mitochondria and nuclei, resulting in apoptosis, DNA intercalation, cell-cycle arrest at the S phase, and light-induced reactive oxygen species production. Intravascular HKHD inhibited tumor growth in A549-implanted mice with good safety. The present study, for the first time, systemically reveals biostability, targetability, chemophotodynamics, and safety of the functionalized novel HKHD.
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