Biological control of individual cells, organs, and organisms is achieved through interplay of a host of specific interactions that involve various peptidic molecules as modulators or effectors. In
tumor cells, these processes may result in uncontrolled growth as a consequence of autocrine and/or paracrine actions. In recent years, growing evidence has accumulated for the important role of
proprotein convertases (PCs) and
peptide alpha-amidation
enzymes in these processes. The widespread belief that these
enzymes are involved in the major features of
tumor progression, namely, invasiveness and
metastasis, has taken place because of their capacity to process and activate many
protein precursors involved in the neoplastic progression and
metastasis. This includes degrading extracellular matrix
proteases, growth promoting factors, and adhesion molecules. Usually, when the processing of these precursor
proteins is achieved by one or more of the known PC family members within the general motif (K/R)-(X)n-(K/R) downward arrow, where n=0, 2, 4, or 6, and X, any
amino acid except Cys, the accomplishment of the maturation of these molecules is attained by various posttranslational modifications, including the carboxy-terminal alpha-amidation. This review article summarizes recent findings on the role of these enzymatic systems in multiple cellular functions that impact on the invasive/metastatic potential of
cancer cells and highlight the potential use of their inhibitors in the treatment of multiple
cancers.