The difference in miR-21 expression levels between invasive and non-invasive breast cancers emphasizes its role in breast cancer invasion

Abstract

MicroRNA-21 (miR-21) overexpression is characteristic for various types of tumors, but it is still unknown whether its expression levels differ between invasive and non-invasive breast carcinomas. The main goal of the study was to determine the difference in miR-21 expression among normal tissue, non-invasive, invasive with non-invasive component, and pure invasive breast cancer samples, to explain its potential role and significance in breast cancer invasiveness. The second goal was to propose miR-21 as molecular marker of breast cancer invasiveness and potential target for future anti-miR therapies for the prevention of invasion and metastasis. In order to reveal the role of miR-21 in breast cancer invasiveness, we measured miR-21 expression levels in 44 breast cancer and four normal samples by stem-loop real-time RT-PCR using TaqMan technology. Relative expression levels of miR-21 were significantly higher in invasive than in other groups (P=0.002) and significantly higher in invasive compared with invasive with non-invasive component group in histological (P=0.043) and nuclear grade 2 (P=0.036), estrogen-receptor-positive (ER+) (P=0.006), progesterone-receptor-positive (PR+) (P=0.008), ER+PR+ (P=0.007), and proliferation index (Ki-67)≤20% (P=0.036) tumors. Our findings suggest that miR-21 could be independent molecular marker of breast cancer invasiveness and potential target for future anti-miR therapies for the prevention of invasion and metastasis.

Circulating Micro-RNAs as Non-invasive Molecular Biomarkers for Early Detection Breast cancer.

“…According to those findings and findings from other previous study , (Petrović et al ,2014) miR-21 is a potential biomarker for breast cancer invasion, rather than carcinogenesis and that it might be great biological marker for regrouping the patients with different receptor status. Another examined miRNA is miR-let7c which was highly significant down regulated in early stages breast cancer with p-value 0.0160.…”

Stat3 regulates ErbB-2 expression and co-opts ErbB-2 nuclear function to induce miR-21 expression, PDCD4 downregulation and breast cancer metastasis

“…29,30 Moreover, previous findings have found a direct correlation between miR-21 levels and the metastatic dissemination of human BC tumor samples. [31][32][33] Our findings revealed that Stat3 regulates ErbB-2 expression and co-opts its nuclear function to induce miR-21 and BC metastasis, highlighting Stat3 and NErbB-2 as novel targets to block metastatic dissemination in MErbB-2-positive BC.…”

Dehydroepiandrosterone-induces miR-21 transcription in HepG2 cells through estrogen receptor β and androgen receptor

“…miR-21 is known to play a role in invasion based on its ability to downregulate PDCD4 (Asangani et al, 2008), RECK and TIMP3 (Gabriely et al, 2008) (Zhu et al, 2008), and SULF1 (Bao et al, 2013). A recent study reported higher miR-21 in invasive ERα+/PR+, but not ERα-/PR−, breast tumors (Petrović et al, 2014). Another study reported that thyroid hormone (T 3 ) stimulated cell migration and invasion of HepG2 cells stably expressing thyroid hormone receptors α1 (TRα1) and TRβ1 by down regulating TIAM1 (Huang et al, 2013).…”