Deregulation of miR-21 and miR-155 and their putative targets after silibinin treatment in T47D breast cancer cells.

Objectives: MicroRNAs (miRNAs) are a class of short RNAs that control the biological processes including cell proliferation, apoptosis and development. Aberrant expression of miRNAs was determined in the different stages of tumor development and metastasis. To study the effect of silibinin on miRNAs expression, we evaluated quantitative expression of miR-21 and miR-155 as two oncomiRs and several potential targets in silibinin-treated T47D cells.

Materials And Methods: The rate of proliferation and apoptosis was measured in silibinin-treated and untreated cells. The expression levels of miR-21 and miR-155 were evaluated in T47D cells treated with silibinin (100 µg/ml). Also, their putative targets were predicted in apoptotic pathways using multiple algorithms; as a confirmation, the transcription level of APAF-1, CASP-9 and BID was evaluated.

Results: In silibinin-treated cells, death was occurred in a dose and time-dependent manner. miR-21 and miR-155 was downregulated in cells treated with silibinin (100 µg/ml). It is noticeable that the expression of their potential targets including CASP-9 and APAF-1 was increased in silibinin-treated cells after 48 hr.

Conclusion: Our findings showed a correlation between the expression of miR-21 and miR-155 and apoptosis in silibinin treated T47D cells. It seems that miRNAs such as miR-21 and miR-155 were regulated by silibinin. Also, increase in the transcript level of APAF-1 and CASP-9 after downregulation of miR-21 and miR-155 might indicate that these genes were targeted by aforementioned miRNAs in T47D cells.