They produce matrix metalloproteinases like matrix metalloproteinase-2 (MMP2), matrix metalloproteinase-9 (MMP9), matrix metalloproteinase-12 (MMP12), and matrix metalloproteinase-19 (MMP19
) [42, 68], to degrade matrix macromolecules, that is, collagen, one of the most important components of ECM.
Due to structural and substrate specificity, MMPs are currently divided into seven classes: collagenases (MMP1, MMP8, MMP13, and MMP18), gelatinases (MMP2 and MMP9), stromelysins (MMP3, MMP10), stromelysin like (MMP11 and MMP12), matrilysins (MMP7 and MMP26), membrane type (MMP14, MMP15, MMP16, MMP17, MMP24, and MMP25), and others (MMP19, MMP20, MMP21, MMP22, MMP23, MMP27, and MMP28) [18, 27, 28].
MMP3, MMP7, MMP9, and MMP19 stimulate tumor growth by releasing IGF (insulin-like growth factor) .
VEGF (vascular endothelial growth factor) stimulates tumor angiogenesis, being released by MMP3, MMP7, MMP9, and MMP19 .
(2-4) Secreted-type MMPs can be classified into 6 subgroups according to their substrate specificity and structural differences (2): (1) collagenases, including tissue collagenase (MMP1), neutrophil collagenase (MMP8), and collagenase 3 (MMP13); (2) gelatinases, such as gelatinase A (MMP2) and gelatinase B (MMP9); (3) stromelysins, including stromelysin 1 (MMP3) and stromelysin 2 (MMP-10); (4) matrilysins, such as matrilysin 1 (MMP7) and matrilysin 2 (MMP26); (5) furin-activated MMPs, including stromelysin 3 (MMP-13) and epilysin (MMP 28); and (6) other MMPs such as metalloelastase (MMP12), MMP19
, enamelysin (MMP-20), MMP21, and MMP-27.