Isolation of breast cancer stem cell from MDA-MB231 cell line using vincristine / Aislamiento de células madre de cáncer de mama de la línea celular MDA-MB231 utilizando vincristina

Cancer has been considered as a stem cell disease. Suspension culture combined with anti-cancer drugs has recently been proposed for isolation of cancer stem cells (CSCs). In the current study, Vincristine as an anti-cancer drug combined with suspension culture was used for isolation and purification of CSCs from human breast cancer cell line (MDA-MB231). The cells were treated with different concentrations of vincristine (0, 2, 4, 6 and 8 ng/ml). Stem cells were identified with the expression of OCT4, nanog, SOX2 and nucleostemin genes by RT-PCR. Mammosphere forming unit was measured upon suspension culture containing EGF, bFGF, LIF, B27, insulin and BSA. The isolated mammospheres were investigated for CD44 expression. Results showed that 4 ng/ml of vincristine for 72 hours could be utilized as the best and most reliable dose which eliminates around 80 % of non-cancer stem cells with no destructive effect on CSCs' viability (P> 0.05). RT-PCR demonstrated that drug treated cells expressed OCT4, nanog, SOX2 and nucleostemin. Mammosphere formation unit of cells pretreated with vincristine was significantly higher than unpretreated ones (P>0.05). Immunofluorescence staining for CD44 depicted high expression of CSC marker among the isolated mammospheres. Vincristine combined with suspension culture can be considered as an appropriate method to isolate CSC.

El cáncer ha sido considerado como una enfermedad de células madre. Recientemente se ha propuesto cultivo en suspensión en combinación con medicamentos contra el cáncer para aislamiento de las células madre del cáncer (CMC). En este estudio se utilizó la vincristina como fármaco anticanceroso combinado con cultivo en suspensión para el aislamiento y purificación de las células madre cancerosas, de la línea celular de cáncer de mama humano (MDA-MB231). Las células se trataron con diferentes concentraciones de vincristina (0, 2, 4, 6 y 8 ng/ml). Las células madre se identificaron mediante la expresión de los genes OCT4, Nanog, SOX2 y nucleostemin por RT-PCR. La unidad de formación mammosphere se midió a través de cultivo en suspensión que contenía EGF, bFGF, LIF, B27, insulina y BSA. Los mammospheres aislados fueron estudiados para la expresión de CD44. Los resultados mostraron que 4 ng/ml de vincristina durante 72 horas podrían ser utilizados como la mejor y más fiable dosis que permite eliminar alrededor del 80 % de las células madre no cancerosas, sin causar un efecto destructivo sobre la viabilidad de las CMC (P> 0,05). La RT-PCR mostró que en las células tratadas con él fármaco hubo expresión de los genes OCT4, Nanog, SOX2 y nucleostemin. La unidad de formación de las células pretratadas con vincristina fue significativamente más alta que las unidades sin tratamiento previo (P>0,05). La inmunofluorescencia para CD44 muestró una alta expresión del marcador de CMC entre mammospheres aisladas. La vincristina en combinación con el cultivo en suspensión puede ser considerado como un método apropiado para aislar CMC.

Dual-Blocking of PI3K and mTOR Improves Chemotherapeutic Effects on SW620 Human Colorectal Cancer Stem Cells by Inducing Differentiation

Cancer stem cells (CSCs) have tumor initiation, self-renewal, metastasis and chemo-resistance properties in various tumors including colorectal cancer. Targeting of CSCs may be essential to prevent relapse of tumors after chemotherapy. Phosphatidylinositol-3-kinase (PI3K) and mammalian target of rapamycin (mTOR) signals are central regulators of cell growth, proliferation, differentiation, and apoptosis. These pathways are related to colorectal tumorigenesis. This study focused on PI3K and mTOR pathways by inhibition which initiate differentiation of SW620 derived CSCs and investigated its effect on tumor progression. By using rapamycin, LY294002, and NVP-BEZ235, respectively, PI3K and mTOR signals were blocked independently or dually in colorectal CSCs. Colorectal CSCs gained their differentiation property and lost their stemness properties most significantly in dual-blocked CSCs. After treated with anti-cancer drug (paclitaxel) on the differentiated CSCs cell viability, self-renewal ability and differentiation status were analyzed. As a result dual-blocking group has most enhanced sensitivity for anti-cancer drug. Xenograft tumorigenesis assay by using immunodeficiency mice also shows that dual-inhibited group more effectively increased drug sensitivity and suppressed tumor growth compared to single-inhibited groups. Therefore it could have potent anti-cancer effects that dual-blocking of PI3K and mTOR induces differentiation and improves chemotherapeutic effects on SW620 human colorectal CSCs.

Sox2 function as a negative regulator to control HAMP expression

BACKGROUND: Hepcidin, encoding by HAMP gene, is the pivotal regulator of iron metabolism, controlling the systemic absorption and transportation of irons from intracellular stores. Abnormal levels of HAMP expression alter plasma iron parameters and lead to iron metabolism disorders. Therefore,itis animportant goal to understand the mechanisms controlling HAMP gene expression. RESULTS: Overexpression of Sox2 decrease basal expression of HAMP or induced by IL-6 or BMP-2, whereas, knockdown of Sox2 can increase HAMP expression, furthermore, two potential Sox2-binding sites were identified within the human HAMP promoter. Indeed, luciferase experiments demonstrated that deletion of any Sox2-binding site impaired the negative regulation of Sox2 on HAMP promoter transcriptional activity in basal conditions. ChIP experiments showed that Sox2 could directly bind to these sites. Finally, we verified the role of Sox2 to negatively regulate HAMP expression in human primary hepatocytes. CONCLUSION: We found that Sox2 as a novel factor to bind with HAMP promoter to negatively regulate HAMP expression, which may be further implicated as a therapeutic option for the amelioration of HAMP-overexpression-related diseases, including iron deficiency anemia.

Enhanced proliferation and differentiation of Oct4- and Sox2-overexpressing human adipose tissue mesenchymal stem cells

Mesenchymal stem cells (MSCs) are attractive candidates for clinical repair or regeneration of damaged tissues. Oct4 and Sox2, which are essential transcription factors for pluripotency and self-renewal, are naturally expressed in MSCs at low levels in early passages, and their levels gradually decrease as the passage number increases. Therefore, to improve MSC proliferation and stemness, we introduced human Oct4 and Sox2 for conferring higher expansion and differentiation capabilities. The Oct4-IRES-Sox2 vector was transfected into human adipose tissue MSCs (ATMSCs) by liposomal transfection and used directly. Oct4 and Sox2 were successfully transfected into ATMSCs, and we confirmed maintenance of MSC surface markers without alterations in both red fluorescent protein (RFP) (control) and Oct4/Sox2-ATMSCs. Enhanced proliferative activity of Oct4/Sox2-ATMSCs was shown by WST-1 assay, and this result was further confirmed by cell counting using trypan blue exclusion for a long period. In addition, FACs cell cycle analysis showed that there was a reduction in the fraction of Oct4/Sox2-ATMSCs in G1 with a concomitant increase in the fraction of cells in S, compared with RFP-ATMSCs. Increased levels of cyclin D1 were also seen in Oct4/Sox2-ATMSCs, indicating acceleration in the transition of cells from G1 to S phase. Furthermore, Oct4/Sox2-overexpressing ATMSCs showed higher differentiation abilities for adipocytes or osteoblasts than controls. The markers of adipogenic or osteogenic differentiation were also upregulated by Oct4/Sox2 overexpression. The improvement in cell proliferation and differentiation using Oct4/Sox2 expression in ATMSCs may be a useful method for expanding the population and increasing the stemness of ATMSCs.