During their evolution
tumor cells acquire and mobilize various mechanisms that crucially affect their capability of proliferation, invasiveness and
metastasis. Recent findings provide evidence that
tumor cell associated
cysteine proteinases such as some lysosomal
cathepsins and apoptotic
caspases are fundamentally involved in specific developmental traits of
tumor cell populations.
Tumor cell exterior-associated
cysteine cathepsins B and L promote
tumor growth, invasion and
metastasis through degradation of extracellular connective matrices and through endothelial cell growth-directed activities. On the other hand,
caspases -3, -7 and -6, generated in
tumor cell cytoplasm via a robust activation of their
zymogens, suppress
tumor cell growth, invasion and
metastasis through proteolytic devitalizing and remodeling of
tumor cells into readily phagocytable apoptotic
corpses.
Tumor cell variants that are deficient in expression of effector
caspase zymogens or are capable to suppress the extrinsic and intrinsic activation mechanisms of effector
caspase zymogens and the activity of
effector caspases have a significant survival advantage in environments of various death stimuli. Advancements in pharmacological targeting of
tumor associated pathogenic lysosomal
cysteine cathepsins and in apoptotic
caspases-oriented conditioning of
tumor cells may substantially contribute to therapeutic control of
tumor diseases.