Drug screening identifies niclosamide as an inhibitor of breast cancer stem-like cells.

The primary cause of death from breast cancer is the progressive growth of tumors and resistance to conventional therapies. It is currently believed that recurrent cancer is repopulated according to a recently proposed cancer stem cell hypothesis. New therapeutic strategies that specifically target cancer stem-like cells may represent a new avenue of cancer therapy. We aimed to discover novel compounds that target breast cancer stem-like cells. We used a dye-exclusion method to isolate side population (SP) cancer cells and, subsequently, subjected these SP cells to a sphere formation assay to generate SP spheres (SPS) from breast cancer cell lines. Surface markers, stemness genes, and tumorigenicity were used to test stem properties. We performed a high-throughput drug screening using these SPS. The effects of candidate compounds were assessed in vitro and in vivo. We successfully generated breast cancer SPS with stem-like properties. These SPS were enriched for CD44(high) (2.8-fold) and CD24(low) (4-fold) cells. OCT4 and ABCG2 were overexpressed in SPS. Moreover, SPS grew tumors at a density of 10(3), whereas an equivalent number of parental cells did not initiate tumor formation. A clinically approved drug, niclosamide, was identified from the LOPAC chemical library of 1,258 compounds. Niclosamide downregulated stem pathways, inhibited the formation of spheroids, and induced apoptosis in breast cancer SPS. Animal studies also confirmed this therapeutic effect. The results of this proof-of-principle study may facilitate the development of new breast cancer therapies in the near future. The extension of niclosamide clinical trials is warranted.

Amelioration of rat collagen-induced arthritis through CD4+ T cells apoptosis and synovial interleukin-17 reduction by indoleamine 2,3-dioxygenase gene therapy.

Indoleamine 2,3-dioxygenase (IDO) has been known as an emerging therapeutic target in autoimmunity-related arthritis. The treatment responses of adenoviral vectors encoding IDO (AdIDO) gene therapy in rat collagen-induced arthritis (CIA) were examined in this study. The therapeutic effects on ankle circumference, articular index, and radiographic and histological scores were evaluated in AdIDO-injected ankle joints. We further determined CD4+ T-cell numbers and their apoptotic status, CD68(+) macrophage numbers, kynurenine (a downstream tryptophan metabolite) concentrations, interleukin-17 (IL-17) levels, and retinoic acid-related orphan receptor γt (RORγt) expression in synovial tissues of CIA rats receiving AdIDO treatment. Reduction of ankle circumference, articular index, and radiographic and histological scores were noted in AdIDO-treated ankles, as compared with those receiving injection of control vectors. Furthermore, IDO gene transfer led to decreased infiltrating CD4+ T cells with enhanced apoptosis, reduced CD68+ macrophage numbers, increased kynurenine levels, lower IL-17 concentrations, and decreased RORγt expression within the ankle joints. In addition, such a therapy diminished type II collagen-specific IL-17 production and RORγt expression in CD4+ T cells from draining lymph nodes of CIA rats. Our results demonstrate for the first time that intra-articular delivery of IDO gene ameliorated ankle arthritis of CIA rats by induction of CD4+ T-cell apoptosis and reduction of synovial IL-17 production through the supplement of kynurenine. Taken together, these findings implicate the novel strategy of using IDO gene as a therapeutic approach in treating patients with rheumatoid arthritis.

Licorice and licochalcone-A induce autophagy in LNCaP prostate cancer cells by suppression of Bcl-2 expression and the mTOR pathway.

Licorice is a common Chinese medicinal herb with antitumor activity. Some components in licorice root have been shown to induce cell cycle arrest or apoptosis in cancer cells. This paper demonstrates for the first time that licorice Glycyrrhiza glabra and its component licochalcone-A (LA) can induce autophagy in addition to apoptosis in human LNCaP prostate cancer cells. Exposure of cells to licorice or LA resulted in several confirmed characteristics of autophagy, including the appearance of autophagic vacuoles revealed by monodansylcadaverine (MDC) staining, formation of acidic vesicular organelles (AVOs), and autophagosome membrane association of microtubule-associated protein 1 light chain 3 (LC3) characterized by cleavage of LC3 and its punctuate redistribution, as well as ultrastructural observation of autophagic vacuoles by transmission electron microscopy. Autophagy induction was accompanied by down-regulation of Bcl-2 and inhibition of the mammalian target of rapamycin (mTOR) pathway. In summary, licorice can induce caspase-dependent and autophagy-related cell death in LNCaP cells.