Moreover, the expression levels of miR-21 and miR-221 were positively correlated with the Enneking clinical stage and the presence of lung metastasis (<i>P</i> <0.05), while the expression levels of miR-143 and miR-106a showed a significant inverse and direct correlation respectively, with the tumor grade.
When comparing liver and lung metastases, miR-194 showed a 1.5-fold; miR-125, miR-127, and miR-192 showed a 2.5-fold; miR-19 and miR-215 a 3-fold; miR-145, miR-199-3, and miR-429 a 5-fold; miR-21 a 7-fold; and, finally, miR-199-5 a 12.5-fold downregulation in liver metastases compared to lung metastases.
We show herein that Mmp8 expression causes a decrease in miR-21 levels that in turn leads to a reduction in tumor growth and lung metastasis formation by MDA-MB-231 (4175) breast cancer cells.
In syngeneic mice injected with B16 cells, EF24 treatment inhibited the formation of lung metastasis, prolonged animal survival, inhibited miR-21 expression and increased the expression of miR-21 target genes.
For example, miR-21 is overexpressed in both male and female breast tumors compared with normal breast tissue and has been associated with advanced stage, lymph node positivity, and reduced survival time. miR-21 knock-down in cell-line models has been associated with increased sensitivity to topotecan and taxol in vitro and the limitation of lung metastasis in vivo.