Inhibitor of DNA-binding 4 contributes to the maintenance and expansion of cancer stem cells in 4T1 mouse mammary cancer cell line / 한국실험동물학회지

The cancer stem cell (CSC) hypothesis proposes that CSCs are the root of cancer. CSC-targeted therapies may prevent cancer relapse and provide more effective treatment. The expression of aldehyde dehydrogenase 1, as assessed by the Aldefluor assay, has been recognized as a marker of CSCs in breast cancer. Inhibitors of DNA-binding proteins (IDs) have an important role in stem cell differentiation. In this study, we examined IDs necessary for the regulation of stem properties in Aldefluorpos 4T1 cells. When the expression profile of IDs in Aldefluorneg and Aldefluorpos 4T1 cells was compared, qRT-PCR analysis showed that ID4 expression was highly upregulated in Aldefluorpos 4T1 cells. In addition, knockdown of ID4 expression suppressed the properties of CSCs, including their sphere-forming ability and side population phenotype. The findings suggest that ID4 may be a therapeutic target for the treatment of advanced breast cancer.

OCT4 Expression Enhances Features of Cancer Stem Cells in a Mouse Model of Breast Cancer / 한국실험동물학회지

The cancer stem cell (CSC) hypothesis proposes that CSCs are responsible for metastasis and disease recurrence. Therefore, targeting CSCs has the potential to significantly improve outcomes for cancer patients. The OCT4 transcription factor gene is a master gene that plays a key role in the self-renewal and pluripotency of stem cells. In this study, we introduced an OCT4 reporting vector into 4T1 mouse breast cancer cells and sorted OCT4 high and OCT4 low cell populations. We then determined whether OCT4 expression is associated with maintenance and expansion of CSCs. We found that OCT4high 4T1 cells have an increased ability to form tumorsphere and a high expression of stem cell markers such as Sca-1, CD133, CD34, and ALDH1, when compared with OCT4low 4T1 cells. In addition, OCT4high 4T1 cells have greater tumorigenic potential in vivo. These findings suggest that OCT4 expression may be a useful target for stem cell-specific cancer therapy.

Induction of Apoptosis of Ewing's Sarcoma Cells by Regulating Fusion Protein Expression

PURPOSE: Fusion genes(EWS-Fli-1 and EW.S-erg) function as transcription activators and are essential for maintaining tumorigenic properties in Ewing's sarcoma cells. Several reports have noted that Ets family transcription factors bind with CBP(CREB binding protein) in vitro. To understand the interaction of fusion proteins and CBP, we studied the CBP protein in TC135 cells expressing the EWS-Fli-1 gene. We also studied the hypothesis that downregulation of fusion gene expression may induce susceptibility to apoptosis in Ewing's sarcoma cells. METHODS: For targeting fusion proteins, we reconstructed the antisense EWS-fli-l, EWS-erg and CBP genes in pcDNA3, and transfected these genes to Ewing's sarcoma cells showing high levels of expression for Ve3 and 5838 genes. These vectors were transfected to cells by the calcium phosphate method, and transformed cells were selected using G418. We measured DNA fragments for apoptosis using FACScan. We used crystal violet staining and MTT assay to evaluate cell viability, and Western blot analysis was used to assess CBP gene expression. RESULTS: Cells transfected with antisense fusion genes Ve3 and 5838 showed inhibition of fusion protein expression. These cells also showed decreased cell viability. Susceptibility to apoptosis was induced by treatment with chemotherapeutic agents at low concentrations. Antisense CBP- transfected cells showed loss of cell viability in O.l% and 0.5% serum. This loss of cell viability was similar to the response by antisense fusion protein-transfected cells treated with chemotherapeutic agents at low concentrations. CONCLUSION: Our results suggest that fusion proteins and CBP co-regulate apoptosis in Ewing's sarcoma cells. Antisense fusion gene therapy may be an useful adjunct in combining with chemotherapeutic regimens to downregulate the expression of fusion proteins in Ewing's sarcoma.

The Effect of Milk on the Bioavailability of 6-mercaptopurine

The purine antimetabolite 6-Mercaptopurine (6-MP) has been in clinical use for over 30 years and is still a widely used agent in the treatment of childhood acute lymphoblastic leukemia. The bioavailibility, clinical efficacy and toxicity of 6-MP administered orally for maintenance therapy of children with acute lymphoblastic leukemia are highly variable in many studies, as well as at differnt times in same patient. there are many factors affecting the bioavailibility of 6-MP. The most notably factor being that concomitantly administered drugs and foods might contribute to a decrease in the bioavailibity of this drug. In our sociocultural environment milk is a major constituent of child's foods. Cow's milk contains a high concentration of xanthine oxidase, which could potentially transform 6-TM into 6-thioxanthine (6-TX) and 6-thiouric acid (6-TUA) which have no more therapeutic effects. In this study, we evaluated the effect of various milk products on the bioavailability of 6-MP. Incubation at 37degrees C for 30 min raw or pasteurized milk resulted in transformation of a large quantity of clinically relevant concentration of 6-MP into 6-TUA. The concomitant adminstration of folic acid and allopurinol has markedly inhibitory effect on the 6-MP destroying activity of milk at clinically relevant concentrations. These observations may help to optimize modalities of administration of 6-MP for the treartment of patients with childhood leukemia.

A Case of Steven-Johnson Syndroe Associated with Cholestatic Hepatitis

A 12-year-old boy developed cholestatic hepatitis with Steven-Johnson syndrome following the use of amoxicillin. The skin lesion and general condition were improved over 2 weeks, but jaundice was gradually aggrevated. We performed liver biopsy, on 30th hospital day, which showed cholestatic hepatitis. The patient improved gradually and liver function was normalized 5 months later.