Fig. 6

Schematic diagram summarizing the role of the miR-140 in the course of breast cancer development. miR-140 expression is inhibited by the action of estrogen receptor or through differential methylation of CpG islands in its promoter region. Upon its expression, two different isoforms are formed that act synergistically to suppress the growth and development of breast cancer. The canonical hsa-miR-140-3p acts by negatively regulating the Wnt, SOX2 and SOX9 [44]. The latter are known to be key stem cell self-renewal regulatory elements. Inhibition of miR-140 expression results in uncontrolled elevation of SOX2, causing an increase in stem cell populations and breast cancer initiation, progression and growth. The 5’isomiR-140-3p acts by reducing cellular viability, cellular migration and arresting the cell cycle in the G0/G1 phase through targeting COL4A1, ITGA6, and MARCKSL1