Table 2.

Changes to ECS components in malignant tissues.

Tissues/Organs	Endocannabinoids	Receptors	Metabolizing Enzymes
Skin	Decreased AEA and increased 2-AG in melanoma [51]	↑ CB2 in melanoma [52]	↑ MAGL [53], and ↑ FAAH in melanoma [45]
Intestine (colorectal)	↑ AEA and 2-AG [54,55] ↑ LPI [55,56]	↓ CB1 [57,58], ↑ GPR55 [57,59], ↑ CB2 and ↓ CB1 [58]	↑ MAGL [54], ↑ FAAH [45]
Lung		↑ CB1 and CB2 [60,61]	↑ FAAH [62], ↑ FAAH [45]
Breast	↑ LPI [63]	↑ CB1 and CB2 [64,65,66,67], ↑ GPR55 [68,69]	↑ FAAH [45]
Brain	↑ AEA and 2-AG in many cancers [70,71,72,73,74]	↑ CNR1, ↑ CNR2, ↑ CB1 and CB2 in glioma [75,76,77,78], ↓ CB1 in glioma [79]	↓ FAAH [80] in glioma, ↑ FAAH in glioma [45]

Changes in ECS components in major cancers. ↑ indicates upregulation, while ↓ indicates downregulation. Italic indicates gene expression (CNR1/CNR2, for example), while non-italic—proteins (CB1/CB2, for example). LPI—lysophosphatidylinositol.