Original ArticlesLMTK3 escapes tumour suppressor miRNAs via sequestration of DDX5
Section snippets
Background
LMTK3 is involved in multiple biological processes, including tumour progression by regulating oestrogen receptor α (ERα) transcription and its stability [1]. Furthermore, high LMTK3 expression has also been associated with poor survival in breast cancer patients [2], while genome-wide studies have revealed that LMTK3 has a crucial role in endocrine resistance via different signalling pathways [3]. We have also demonstrated a role of LMTK3 in breast cancer cell motility, migration, and invasion
Cell culture
Human breast cancer cell lines MCF7 and MDA-MB-231 were purchased from the American Type Culture Collection and were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% FCS and 1% penicillin streptomycin and L-glutamine. MCF7 and MDA-MB-231 that stably overexpress LMTK3 were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% foetal calf serum (FCS), G418 (500 µg/ml; Invitrogen) and 1% penicillin streptomycin and L-glutamine. All cells were
Overexpression of LMTK3 up-regulates a subset of miRNAs
In order to investigate whether LMTK3 regulates miRNA levels, we used Nanostring nCounter to perform a miRNA expression profile in parental MCF7 cells and MCF7 cells stably overexpressing LMTK3 (MCF7-LMTK3). Fold change assessments (>or <1.5×) and t-tests (P < 0.01) criteria revealed a small number of up- and down-regulated miRNAs in MCF7-LMTK3 cells compared to parental MCF7 (Fig. 1a–c). We further validated most of the significantly modified miRNAs (up- or down-regulated) by performing
Discussion
LMTK3 is abnormally abundant in most breast cancer cell lines. Our recent work revealed that LMTK3 acts as a transcription factor [5], leading to hypothesize its involvement in miRNAs regulation. In this study, using miRNA expression profiling, we identified a subset of miRNAs regulated by LMTK3. Interestingly, miR-34a, miR-196a2 and miR-182 were regulated at the post-transcriptional level in MCF7 cells stably overexpressing LMTK3 (MCF7-LMTK3). Although miR-34a, miR-182 and miR-196a2 belong to
Conflict of interest
The authors declare no competing financial interests.
Authors' contributions
JJ acquired the data and performed most of the experiments. JJ, JS and GG contributed to conception and design. NK, MM performed some of the experiments and RF, NK and MM analysed some of the data. VH and LC provided conceptual advices. JJ, RF, GG and LC wrote the paper. All authors read and approved the final manuscript.
Acknowledgments
We would like to thank Adam Frampton, Jonathan Krell and Joao Nunes for the helpful discussion. This work was supported by Action Against Cancer. We would also like to thank Richard and Evelina Girling and the “kinase group” for their support.
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