Figure 2.

Autophagy is positively regulated by AMPK and HIF signaling pathways with the mTOR pathway serving as a negative regulator. Upon induction of autophagy damaged organelles and macromolecules are engulfed in a double membrane vesicle known as an autophagosome. Autophagosomes traffic along microtubules towards the lysosome to allow for fusion and enzymatic degradation of autophagosomes and their contents into macromolecular subunits (flux). Runx2 serves a dual role in promoting metastasis, (1) through the enhancement of microtubule acetylation and autophagosome trafficking, and (2) providing transcriptional support and upregulating genes implicated in bone metastasis such as VEGEF, assorted MMP’s, osteopontin (OPN), and bone sialoprotein (BSP), among others.