Impacts of microRNA-215 on cell proliferation and chemotherapy resistance in colon cancer and osteosarcoma

2542 Background: Translational control plays a key role in resistance to anti-cancer drug treatment. MicroRNAs regulate gene expression at the post-transcriptional level, mainly by interacting with 3'-UTR of their mRNA targets. Methods: miR-215 was ectopically expressed by transient transfection in both human colon cancer cell lines and osteosarcoma cell lines. The impact of miR-215 on cell proliferation, cell cycle control, chemosensitivity and down stream targets were characterized. The expression of miR-215 in colorectal cancer specimens and normal adjacent tissues was quantified by real time-qRT-PCR analysis. Results: In this study, we discovered that miR-215 down-regulates the expression of both dihydrofolate reductase (DHFR) and thymidylate synthase (TS), two of the most important chemotherapeutic targets, in human osteosarcoma U-2 OS and colon cancer HCT-116 (wt-p53) cell lines. Cells with elevated miR-215 expression are more resistant to DHFR inhibitor methotrexate (MTX) or TS inhibitor Tomudex (TDX) treatment. Ectopically over-expressing miR-215 triggers reduced cell proliferation and increased G2 arrest, at least in part, through the induction of p53 and p21. miR-215 transfected cells with reduced proliferating phenotype were resist to MTX or TDX treatment due to deceased cell cycle in S phase. The expression of endogeneous miR-215 was highly elevated in CD133+/HI CD44+/HI colon cancer stem cells compared to CD133- CD44- colon cancer cells, suggesting that tumor stem cells may be avoiding cellular and DNA damage caused by chemotherapy with a reduced proliferating phenotype mediated by certain miRNAs such as miR-215. The elevated expression of miR-215 in colon cancer stem cells with slow proliferation rate and resistance to chemotherapy further supports the role of miR-215 in cell proliferation and chemotherapy resistance. Conclusions: miR-215 may have a unique potential as a novel therapeutic target and biomarker candidate in cancer. No significant financial relationships to disclose.

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Targeting the androgen receptor as a novel therapeutic strategy for high-grade gliomas by suppressing glioma cancer stem cells.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.15_suppl.e13504 ◽

2019 ◽

Vol 37 (15_suppl) ◽

pp. e13504-e13504 ◽

Cited By ~ 1

Author(s):

Nan Zhao ◽

Shaheen Ahmed ◽

Fei Wang ◽

DiMaio J Dominick ◽

Chi Lin ◽

...

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Cell Proliferation ◽

Androgen Receptor ◽

Cancer Stem Cells ◽

Cell Lines ◽

Proliferation Assay ◽

Cell Proliferation Assay ◽

Expression Levels

e13504 Background: Glioblastoma (GBM) is the most aggressive and most common type of primary brain malignancies with median overall survival being only 20.9 months. The incidence of GBM is 50% greater in men than in women, and GBM transplanted into animals grow at a slower rate in females compared with males. Gender difference in GBM indicates that sex hormones such as androgen receptor (AR) may be involved in the tumorigenesis of GBM. A newer generation of AR antagonist, Enzalutamide, is available for prostate cancer treatment in clinic and can pass the blood-brain barrier, thus a good candidate for GBM treatment. Methods: Cell proliferation assay, cell cycle analysis, and cell apoptosis assay were performed on different GBM cell lines after Enzalutamide treatment. After treating GBM cells with or without Enzalutamide in mono-layer cell culturing or tumor spheres, cancer stem cell sub-population (CD133+ cells) in different groups was compared using flow cytometry. After enriching GBM cancer stem cells by sorting CD133+ U87MG cells out, cell proliferation assay was performed on CD133+ U87MG cells. Western blotting was performed comparing marker gene expression levels including CD133 and c-Myc with total protein isolated from GBM cells treated with Enzalutamide at different time points. A syngeneic orthotopic GBM mouse model was used for in vivo study. The size of tumors in the brain was monitored weekly with and without Enzalutamide treatment by in vivo imaging system for the luciferase activities. Results: Enzalutamide inhibited the proliferation of GBM cells both in vitro and in vivo. Enzalutamide induced apoptosis of GBM cells as well as arrested the cell cycle at G2/M phase in a cell cycle that has a potential of radio-sensitizing effect. Enzalutamide decreased the cancer stem cells population both in cultured mono-layer cells and in tumor spheres. Enzalutamide inhibited the proliferation of CD133+ U87MG cells after four days’ treatment. c-Myc is a proto-oncogene and required for maintenance of GBM cancer stem cells. Both CD133 and c-Myc expression levels decreased in GBM cell lines after Enzalutamide treatment in a time-dependent manner. Conclusions: Enzalutamide targets cancer stem cells and inhibits the proliferation of GBM.

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