The miR-17 family, composed of miR-17-5p, miR-20a/b, miR-106a/b and miR-93, has been demonstrated to take part in critical pathways that regulate cellular life and death decisions during normal development and in malignancy. Previous studies have shown that the expression of miR-17
family members has close relationship with the expression of c-Myc. Another study has reported p21 is a direct target of miR-17 family and their silencing of p21 contributes to tumor cell proliferation in part. Since c-Myc is a potent transcriptional repressor of p21, these findings suggest
that c-Myc may negatively modulate p21 expression through an additional pathway except transcriptional suppression. In the study presented here, we compared p21 mRNA in the nucleus and cytoplasm of c-Myc stable transfectants with its control, which indicated further repression of p21 by c-Myc
at the post-transcriptional level. Stem-loop and conventional real-time PCR showed elevated expression of some members in miR-17 family and their primary transcripts when c-Myc was stably overexpressed. To further investigate the relationship of c-Myc, miR-17 family and p21, we antagonized
the expression of each miR-17 family member by transfection of their antisense oligonucleotides respectively in transfectants constitutively overexpressing c-Myc or not, and found that the restoration of p21 expression by treatment above was much stronger in the presence of c-Myc. These results
suggest c-Myc could further repress p21 expression at the post-transcriptional level through some, but not all, members of miR-17 family.
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Document Type: Research Article
Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, Cancer Institute & Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100021, P.R. China
Publication date: November 1, 2010
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The International Journal of Oncology provides an international forum for the publication of the latest, cutting-edge research in the broad area of oncology and cancer treatment. The journal accepts original high quality works and reviews on all aspects of oncology research including carcinogenesis, metastasis, epidemiology, chemotherapy and viral oncology. Through fair and efficient peer review, the journal is dedicated to publishing top tier research in the field, offering authors rapid publication as well as high standards of copy-editing and production. The International Journal of Oncology is published on a monthly basis in both print and early online.
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