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Clinicopathological Analysis of miRNA Expression in Breast Cancer Tissues by Using miRNA In Situ Hybridization
Published on: June 7, 2016
miRNA-520b and miR-520e sensitize breast cancer cells to complement attack via directly targeting 3'UTR of CD46
Wenjing Cui1, Yiwen Zhang, Nan Hu
1Department of Biochemistry, The Key Laboratory of Bioactive Materials, Ministry of Education, Institute for Molecular Biology and Biochemistry, College of Life Sciences, Nankai University, Tianjin, China.
Abstract:
MicroRNAs (miRNAs), non-coding RNAs that function as post-transcriptional gene regulators, play a pivotal role in cancer development. In the present study, we elucidated the roles of miR-520b and miR-520e in breast cancer cells. We examined the expression levels of miR-520b and miR-520e in the immortalized breast cell line, HBL-100, and in three breast cancer cell lines: MCF-7, LM-MCF-7 and MDA-MB-231. We show the expression levels of miR-520b and miR-520e in the breast cancer cell lines were lower than that in the HBL-100 cells. Furthermore, the breast cancer cell lines showed less sensitivity to complement-dependent cytotoxicity (CDC). We found that overexpression of miR-520b and miR-520e increases the sensitivity of the breast cancer cells to CDC, whereas further suppression of miR-520b and miR-520e decreases the sensitivity of the breast cancer cells to CDC. We then demonstrate that miR-520b and miR-520e are able to directly target the 3'untranslated regions (3'UTR) of the membrane-bound complement regulatory protein CD46; suggesting that miR-520b and miR-520e down-regulate CD46 at post-transcriptional level. Enzyme-linked immunosorbent assay (ELISA) showed that overexpression of miR-520b and miR-520e results in the increased expression of C3b, which is mediated by downregulated CD46. These results suggest that miRNA-520b and miR-520e mediated down-regulation of CD46 induces opsonization of cancer cells via an alternative pathway resulting in complement activation. Thus, we conclude that miR-520b and miR-520e contribute to CDC in breast cancer cells via directly targeting the 3'UTR of CD46.
Insights
MicroRNAs miR-520b and miR-520e are downregulated in breast cancer cells, reducing sensitivity to complement-dependent cytotoxicity (CDC). Restoring these microRNAs enhances CDC by targeting CD46, offering a potential therapeutic strategy.
Area of Science:
- Molecular Biology
- Cancer Research
- Immunology
Background:
- MicroRNAs (miRNAs) are key post-transcriptional regulators implicated in cancer development.
- Dysregulation of specific miRNAs can influence cancer cell behavior and response to therapy.
Purpose of the Study:
- To investigate the roles of miR-520b and miR-520e in breast cancer.
- To determine the impact of these miRNAs on complement-dependent cytotoxicity (CDC).
Main Methods:
- Expression analysis of miR-520b and miR-520e in breast cell lines.
- Assessment of breast cancer cell sensitivity to CDC upon miRNA modulation.
- Target validation using 3'UTR assays and ELISA to measure C3b expression.
Main Results:
- miR-520b and miR-520e expression is lower in breast cancer cells compared to normal cells.
- Overexpression of miR-520b/miR-520e enhances breast cancer cell sensitivity to CDC.
- These miRNAs directly target CD46, downregulating its expression and increasing C3b-mediated opsonization.
Conclusions:
- miR-520b and miR-520e play a significant role in breast cancer's susceptibility to CDC.
- Targeting CD46 via miR-520b/miR-520e represents a potential mechanism to enhance anti-cancer immunity.
